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<h1>Tutorial: HTTP/2 client<a class="headerlink" href="#tutorial-http-2-client" title="Permalink to this headline"></a></h1>
<p>In this tutorial, we are going to write very primitive HTTP/2
client. The complete source code, <a class="reference internal" href="#libevent-client-c">libevent-client.c</a>, is attached at
the end of this page. It also resides in examples directory in the
archive or repository.</p>
<p>This simple client takes 1 argument, HTTPS URI, and retrieves the
resource denoted by the URI. Its synopsis is like this:</p>
<div class="highlight-c"><div class="highlight"><pre>$ libevent-client HTTPS_URI
</pre></div>
</div>
<p>We use libevent in this tutorial to handle networking I/O. Please
note that nghttp2 itself does not depend on libevent.</p>
<p>First we do some setup routine for libevent and OpenSSL library in
function <tt class="docutils literal"><span class="pre">main()</span></tt> and <tt class="docutils literal"><span class="pre">run()</span></tt>, which is not so relevant to nghttp2
library use. The one thing you should look at is setup NPN callback.
The NPN callback is used for the client to select the next application
protocol over the SSL/TLS transport. In this tutorial, we use
<a class="reference internal" href="apiref.html#c.nghttp2_select_next_protocol" title="nghttp2_select_next_protocol"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_select_next_protocol()</span></tt></a> function to select the HTTP/2
protocol the library supports:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">static</span> <span class="kt">int</span> <span class="nf">select_next_proto_cb</span><span class="p">(</span><span class="n">SSL</span><span class="o">*</span> <span class="n">ssl</span><span class="p">,</span>
<span class="kt">unsigned</span> <span class="kt">char</span> <span class="o">**</span><span class="n">out</span><span class="p">,</span> <span class="kt">unsigned</span> <span class="kt">char</span> <span class="o">*</span><span class="n">outlen</span><span class="p">,</span>
<span class="k">const</span> <span class="kt">unsigned</span> <span class="kt">char</span> <span class="o">*</span><span class="n">in</span><span class="p">,</span> <span class="kt">unsigned</span> <span class="kt">int</span> <span class="n">inlen</span><span class="p">,</span>
<span class="kt">void</span> <span class="o">*</span><span class="n">arg</span><span class="p">)</span>
<span class="p">{</span>
<span class="k">if</span><span class="p">(</span><span class="n">nghttp2_select_next_protocol</span><span class="p">(</span><span class="n">out</span><span class="p">,</span> <span class="n">outlen</span><span class="p">,</span> <span class="n">in</span><span class="p">,</span> <span class="n">inlen</span><span class="p">)</span> <span class="o">&lt;=</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">errx</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="s">&quot;Server did not advertise &quot;</span> <span class="n">NGHTTP2_PROTO_VERSION_ID</span><span class="p">);</span>
<span class="p">}</span>
<span class="k">return</span> <span class="n">SSL_TLSEXT_ERR_OK</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<p>The callback is set to the SSL_CTX object using
<tt class="docutils literal"><span class="pre">SSL_CTX_set_next_proto_select_cb()</span></tt> function:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">static</span> <span class="n">SSL_CTX</span><span class="o">*</span> <span class="nf">create_ssl_ctx</span><span class="p">(</span><span class="kt">void</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">SSL_CTX</span> <span class="o">*</span><span class="n">ssl_ctx</span><span class="p">;</span>
<span class="n">ssl_ctx</span> <span class="o">=</span> <span class="n">SSL_CTX_new</span><span class="p">(</span><span class="n">SSLv23_client_method</span><span class="p">());</span>
<span class="k">if</span><span class="p">(</span><span class="o">!</span><span class="n">ssl_ctx</span><span class="p">)</span> <span class="p">{</span>
<span class="n">errx</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="s">&quot;Could not create SSL/TLS context: %s&quot;</span><span class="p">,</span>
<span class="n">ERR_error_string</span><span class="p">(</span><span class="n">ERR_get_error</span><span class="p">(),</span> <span class="nb">NULL</span><span class="p">));</span>
<span class="p">}</span>
<span class="n">SSL_CTX_set_options</span><span class="p">(</span><span class="n">ssl_ctx</span><span class="p">,</span>
<span class="n">SSL_OP_ALL</span> <span class="o">|</span> <span class="n">SSL_OP_NO_SSLv2</span> <span class="o">|</span> <span class="n">SSL_OP_NO_COMPRESSION</span> <span class="o">|</span>
<span class="n">SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION</span><span class="p">);</span>
<span class="n">SSL_CTX_set_next_proto_select_cb</span><span class="p">(</span><span class="n">ssl_ctx</span><span class="p">,</span> <span class="n">select_next_proto_cb</span><span class="p">,</span> <span class="nb">NULL</span><span class="p">);</span>
<span class="k">return</span> <span class="n">ssl_ctx</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<p>We use <tt class="docutils literal"><span class="pre">http2_session_data</span></tt> structure to store the data related to
the HTTP/2 session:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">typedef</span> <span class="k">struct</span> <span class="p">{</span>
<span class="n">nghttp2_session</span> <span class="o">*</span><span class="n">session</span><span class="p">;</span>
<span class="k">struct</span> <span class="n">evdns_base</span> <span class="o">*</span><span class="n">dnsbase</span><span class="p">;</span>
<span class="k">struct</span> <span class="n">bufferevent</span> <span class="o">*</span><span class="n">bev</span><span class="p">;</span>
<span class="n">http2_stream_data</span> <span class="o">*</span><span class="n">stream_data</span><span class="p">;</span>
<span class="p">}</span> <span class="n">http2_session_data</span><span class="p">;</span>
</pre></div>
</div>
<p>Since this program only handles 1 URI, it uses only 1 stream. We store
its stream specific data in <tt class="docutils literal"><span class="pre">http2_stream_data</span></tt> structure and the
<tt class="docutils literal"><span class="pre">stream_data</span></tt> points to it. The <tt class="docutils literal"><span class="pre">struct</span> <span class="pre">http2_stream_data</span></tt> is
defined as follows:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">typedef</span> <span class="k">struct</span> <span class="p">{</span>
<span class="cm">/* The NULL-terminated URI string to retreive. */</span>
<span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">uri</span><span class="p">;</span>
<span class="cm">/* Parsed result of the |uri| */</span>
<span class="k">struct</span> <span class="n">http_parser_url</span> <span class="o">*</span><span class="n">u</span><span class="p">;</span>
<span class="cm">/* The authroity portion of the |uri|, not NULL-terminated */</span>
<span class="kt">char</span> <span class="o">*</span><span class="n">authority</span><span class="p">;</span>
<span class="cm">/* The path portion of the |uri|, including query, not</span>
<span class="cm"> NULL-terminated */</span>
<span class="kt">char</span> <span class="o">*</span><span class="n">path</span><span class="p">;</span>
<span class="cm">/* The length of the |authority| */</span>
<span class="kt">size_t</span> <span class="n">authoritylen</span><span class="p">;</span>
<span class="cm">/* The length of the |path| */</span>
<span class="kt">size_t</span> <span class="n">pathlen</span><span class="p">;</span>
<span class="cm">/* The stream ID of this stream */</span>
<span class="kt">int32_t</span> <span class="n">stream_id</span><span class="p">;</span>
<span class="p">}</span> <span class="n">http2_stream_data</span><span class="p">;</span>
</pre></div>
</div>
<p>We creates and initializes these structures in
<tt class="docutils literal"><span class="pre">create_http2_session_data()</span></tt> and <tt class="docutils literal"><span class="pre">create_http2_stream_data()</span></tt>
respectively.</p>
<p>Then we call function <tt class="docutils literal"><span class="pre">initiate_connection()</span></tt> to start connecting to
the remote server:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">static</span> <span class="kt">void</span> <span class="nf">initiate_connection</span><span class="p">(</span><span class="k">struct</span> <span class="n">event_base</span> <span class="o">*</span><span class="n">evbase</span><span class="p">,</span>
<span class="n">SSL_CTX</span> <span class="o">*</span><span class="n">ssl_ctx</span><span class="p">,</span>
<span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">host</span><span class="p">,</span> <span class="kt">uint16_t</span> <span class="n">port</span><span class="p">,</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="kt">int</span> <span class="n">rv</span><span class="p">;</span>
<span class="k">struct</span> <span class="n">bufferevent</span> <span class="o">*</span><span class="n">bev</span><span class="p">;</span>
<span class="n">SSL</span> <span class="o">*</span><span class="n">ssl</span><span class="p">;</span>
<span class="n">ssl</span> <span class="o">=</span> <span class="n">create_ssl</span><span class="p">(</span><span class="n">ssl_ctx</span><span class="p">);</span>
<span class="n">bev</span> <span class="o">=</span> <span class="n">bufferevent_openssl_socket_new</span><span class="p">(</span><span class="n">evbase</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">,</span> <span class="n">ssl</span><span class="p">,</span>
<span class="n">BUFFEREVENT_SSL_CONNECTING</span><span class="p">,</span>
<span class="n">BEV_OPT_DEFER_CALLBACKS</span> <span class="o">|</span>
<span class="n">BEV_OPT_CLOSE_ON_FREE</span><span class="p">);</span>
<span class="n">bufferevent_setcb</span><span class="p">(</span><span class="n">bev</span><span class="p">,</span> <span class="n">readcb</span><span class="p">,</span> <span class="n">writecb</span><span class="p">,</span> <span class="n">eventcb</span><span class="p">,</span> <span class="n">session_data</span><span class="p">);</span>
<span class="n">rv</span> <span class="o">=</span> <span class="n">bufferevent_socket_connect_hostname</span><span class="p">(</span><span class="n">bev</span><span class="p">,</span> <span class="n">session_data</span><span class="o">-&gt;</span><span class="n">dnsbase</span><span class="p">,</span>
<span class="n">AF_UNSPEC</span><span class="p">,</span> <span class="n">host</span><span class="p">,</span> <span class="n">port</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">rv</span> <span class="o">!=</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">errx</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="s">&quot;Could not connect to the remote host %s&quot;</span><span class="p">,</span> <span class="n">host</span><span class="p">);</span>
<span class="p">}</span>
<span class="n">session_data</span><span class="o">-&gt;</span><span class="n">bev</span> <span class="o">=</span> <span class="n">bev</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<p>We set 3 callbacks for the bufferevent: <tt class="docutils literal"><span class="pre">reacb</span></tt>, <tt class="docutils literal"><span class="pre">writecb</span></tt> and
<tt class="docutils literal"><span class="pre">eventcb</span></tt>.</p>
<p>The <tt class="docutils literal"><span class="pre">eventcb()</span></tt> is invoked by libevent event loop when an event
(e.g., connection has been established, timeout, etc) happens on the
underlying network socket:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">static</span> <span class="kt">void</span> <span class="nf">eventcb</span><span class="p">(</span><span class="k">struct</span> <span class="n">bufferevent</span> <span class="o">*</span><span class="n">bev</span><span class="p">,</span> <span class="kt">short</span> <span class="n">events</span><span class="p">,</span> <span class="kt">void</span> <span class="o">*</span><span class="n">ptr</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">ptr</span><span class="p">;</span>
<span class="k">if</span><span class="p">(</span><span class="n">events</span> <span class="o">&amp;</span> <span class="n">BEV_EVENT_CONNECTED</span><span class="p">)</span> <span class="p">{</span>
<span class="kt">int</span> <span class="n">fd</span> <span class="o">=</span> <span class="n">bufferevent_getfd</span><span class="p">(</span><span class="n">bev</span><span class="p">);</span>
<span class="kt">int</span> <span class="n">val</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
<span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="s">&quot;Connected</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">);</span>
<span class="n">setsockopt</span><span class="p">(</span><span class="n">fd</span><span class="p">,</span> <span class="n">IPPROTO_TCP</span><span class="p">,</span> <span class="n">TCP_NODELAY</span><span class="p">,</span> <span class="p">(</span><span class="kt">char</span> <span class="o">*</span><span class="p">)</span><span class="o">&amp;</span><span class="n">val</span><span class="p">,</span> <span class="k">sizeof</span><span class="p">(</span><span class="n">val</span><span class="p">));</span>
<span class="n">initialize_nghttp2_session</span><span class="p">(</span><span class="n">session_data</span><span class="p">);</span>
<span class="n">send_client_connection_header</span><span class="p">(</span><span class="n">session_data</span><span class="p">);</span>
<span class="n">submit_request</span><span class="p">(</span><span class="n">session_data</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">session_send</span><span class="p">(</span><span class="n">session_data</span><span class="p">)</span> <span class="o">!=</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">delete_http2_session_data</span><span class="p">(</span><span class="n">session_data</span><span class="p">);</span>
<span class="p">}</span>
<span class="k">return</span><span class="p">;</span>
<span class="p">}</span>
<span class="k">if</span><span class="p">(</span><span class="n">events</span> <span class="o">&amp;</span> <span class="n">BEV_EVENT_EOF</span><span class="p">)</span> <span class="p">{</span>
<span class="n">warnx</span><span class="p">(</span><span class="s">&quot;Disconnected from the remote host&quot;</span><span class="p">);</span>
<span class="p">}</span> <span class="k">else</span> <span class="k">if</span><span class="p">(</span><span class="n">events</span> <span class="o">&amp;</span> <span class="n">BEV_EVENT_ERROR</span><span class="p">)</span> <span class="p">{</span>
<span class="n">warnx</span><span class="p">(</span><span class="s">&quot;Network error&quot;</span><span class="p">);</span>
<span class="p">}</span> <span class="k">else</span> <span class="k">if</span><span class="p">(</span><span class="n">events</span> <span class="o">&amp;</span> <span class="n">BEV_EVENT_TIMEOUT</span><span class="p">)</span> <span class="p">{</span>
<span class="n">warnx</span><span class="p">(</span><span class="s">&quot;Timeout&quot;</span><span class="p">);</span>
<span class="p">}</span>
<span class="n">delete_http2_session_data</span><span class="p">(</span><span class="n">session_data</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
<p>For <tt class="docutils literal"><span class="pre">BEV_EVENT_EOF</span></tt>, <tt class="docutils literal"><span class="pre">BEV_EVENT_ERROR</span></tt> and <tt class="docutils literal"><span class="pre">BEV_EVENT_TIMEOUT</span></tt>
event, we just simply tear down the connection. The
<tt class="docutils literal"><span class="pre">BEV_EVENT_CONNECTED</span></tt> event is invoked when SSL/TLS handshake is
finished successfully. We first initialize nghttp2 session object in
<tt class="docutils literal"><span class="pre">initialize_nghttp2_session()</span></tt> function:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">static</span> <span class="kt">void</span> <span class="nf">initialize_nghttp2_session</span><span class="p">(</span><span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">nghttp2_session_callbacks</span> <span class="n">callbacks</span> <span class="o">=</span> <span class="p">{</span><span class="mi">0</span><span class="p">};</span>
<span class="n">callbacks</span><span class="p">.</span><span class="n">send_callback</span> <span class="o">=</span> <span class="n">send_callback</span><span class="p">;</span>
<span class="n">callbacks</span><span class="p">.</span><span class="n">before_frame_send_callback</span> <span class="o">=</span> <span class="n">before_frame_send_callback</span><span class="p">;</span>
<span class="n">callbacks</span><span class="p">.</span><span class="n">on_frame_recv_callback</span> <span class="o">=</span> <span class="n">on_frame_recv_callback</span><span class="p">;</span>
<span class="n">callbacks</span><span class="p">.</span><span class="n">on_data_chunk_recv_callback</span> <span class="o">=</span> <span class="n">on_data_chunk_recv_callback</span><span class="p">;</span>
<span class="n">callbacks</span><span class="p">.</span><span class="n">on_stream_close_callback</span> <span class="o">=</span> <span class="n">on_stream_close_callback</span><span class="p">;</span>
<span class="n">callbacks</span><span class="p">.</span><span class="n">on_header_callback</span> <span class="o">=</span> <span class="n">on_header_callback</span><span class="p">;</span>
<span class="n">callbacks</span><span class="p">.</span><span class="n">on_begin_headers_callback</span> <span class="o">=</span> <span class="n">on_begin_headers_callback</span><span class="p">;</span>
<span class="n">nghttp2_session_client_new</span><span class="p">(</span><span class="o">&amp;</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">session</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">callbacks</span><span class="p">,</span> <span class="n">session_data</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
<p>Since we are creating client, we use <a class="reference internal" href="apiref.html#c.nghttp2_session_client_new" title="nghttp2_session_client_new"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_session_client_new()</span></tt></a> to
initialize nghttp2 session object. We setup 7 callbacks for the
nghttp2 session. We&#8217;ll explain these callbacks later.</p>
<p>The <tt class="xref c c-func docutils literal"><span class="pre">delete_http2_session_data()</span></tt> destroys <tt class="docutils literal"><span class="pre">session_data</span></tt> and frees
its bufferevent, so it closes underlying connection as well. It also
calls <a class="reference internal" href="apiref.html#c.nghttp2_session_del" title="nghttp2_session_del"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_session_del()</span></tt></a> to delete nghttp2 session object.</p>
<p>We begin HTTP/2 communication by sending client connection preface,
which is 24 bytes magic byte sequence
(<a class="reference internal" href="apiref.html#c.NGHTTP2_CLIENT_CONNECTION_PREFACE" title="NGHTTP2_CLIENT_CONNECTION_PREFACE"><tt class="xref c c-macro docutils literal"><span class="pre">NGHTTP2_CLIENT_CONNECTION_PREFACE</span></tt></a>) and SETTINGS frame. The
transmission of client connection header is done in
<tt class="docutils literal"><span class="pre">send_client_connection_header()</span></tt>:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">static</span> <span class="kt">void</span> <span class="nf">send_client_connection_header</span><span class="p">(</span><span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">nghttp2_settings_entry</span> <span class="n">iv</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span> <span class="o">=</span> <span class="p">{</span>
<span class="p">{</span> <span class="n">NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS</span><span class="p">,</span> <span class="mi">100</span> <span class="p">}</span>
<span class="p">};</span>
<span class="kt">int</span> <span class="n">rv</span><span class="p">;</span>
<span class="n">bufferevent_write</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">bev</span><span class="p">,</span>
<span class="n">NGHTTP2_CLIENT_CONNECTION_PREFACE</span><span class="p">,</span>
<span class="n">NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN</span><span class="p">);</span>
<span class="n">rv</span> <span class="o">=</span> <span class="n">nghttp2_submit_settings</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">session</span><span class="p">,</span> <span class="n">NGHTTP2_FLAG_NONE</span><span class="p">,</span>
<span class="n">iv</span><span class="p">,</span> <span class="n">ARRLEN</span><span class="p">(</span><span class="n">iv</span><span class="p">));</span>
<span class="k">if</span><span class="p">(</span><span class="n">rv</span> <span class="o">!=</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">errx</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="s">&quot;Could not submit SETTINGS: %s&quot;</span><span class="p">,</span> <span class="n">nghttp2_strerror</span><span class="p">(</span><span class="n">rv</span><span class="p">));</span>
<span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
<p>Here we specify SETTINGS_MAX_CONCURRENT_STREAMS to 100, which is
really not needed for this tiny example progoram, but we are
demonstrating the use of SETTINGS frame. To queue the SETTINGS frame
for the transmission, we use <a class="reference internal" href="apiref.html#c.nghttp2_submit_settings" title="nghttp2_submit_settings"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_submit_settings()</span></tt></a>. Note that
<a class="reference internal" href="apiref.html#c.nghttp2_submit_settings" title="nghttp2_submit_settings"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_submit_settings()</span></tt></a> function only queues the frame and not
actually send it. All <tt class="docutils literal"><span class="pre">nghttp2_submit_*()</span></tt> family functions have
this property. To actually send the frame, <a class="reference internal" href="apiref.html#c.nghttp2_session_send" title="nghttp2_session_send"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_session_send()</span></tt></a> is
used, which is described about later.</p>
<p>After the transmission of client connection header, we enqueue HTTP
request in <tt class="docutils literal"><span class="pre">submit_request()</span></tt> function:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">static</span> <span class="kt">void</span> <span class="nf">submit_request</span><span class="p">(</span><span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="kt">int</span> <span class="n">rv</span><span class="p">;</span>
<span class="n">http2_stream_data</span> <span class="o">*</span><span class="n">stream_data</span> <span class="o">=</span> <span class="n">session_data</span><span class="o">-&gt;</span><span class="n">stream_data</span><span class="p">;</span>
<span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">uri</span> <span class="o">=</span> <span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">uri</span><span class="p">;</span>
<span class="k">const</span> <span class="k">struct</span> <span class="n">http_parser_url</span> <span class="o">*</span><span class="n">u</span> <span class="o">=</span> <span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">u</span><span class="p">;</span>
<span class="n">nghttp2_nv</span> <span class="n">hdrs</span><span class="p">[]</span> <span class="o">=</span> <span class="p">{</span>
<span class="n">MAKE_NV2</span><span class="p">(</span><span class="s">&quot;:method&quot;</span><span class="p">,</span> <span class="s">&quot;GET&quot;</span><span class="p">),</span>
<span class="n">MAKE_NV</span><span class="p">(</span><span class="s">&quot;:scheme&quot;</span><span class="p">,</span>
<span class="o">&amp;</span><span class="n">uri</span><span class="p">[</span><span class="n">u</span><span class="o">-&gt;</span><span class="n">field_data</span><span class="p">[</span><span class="n">UF_SCHEMA</span><span class="p">].</span><span class="n">off</span><span class="p">],</span> <span class="n">u</span><span class="o">-&gt;</span><span class="n">field_data</span><span class="p">[</span><span class="n">UF_SCHEMA</span><span class="p">].</span><span class="n">len</span><span class="p">),</span>
<span class="n">MAKE_NV</span><span class="p">(</span><span class="s">&quot;:authority&quot;</span><span class="p">,</span> <span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">authority</span><span class="p">,</span> <span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">authoritylen</span><span class="p">),</span>
<span class="n">MAKE_NV</span><span class="p">(</span><span class="s">&quot;:path&quot;</span><span class="p">,</span> <span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">path</span><span class="p">,</span> <span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">pathlen</span><span class="p">)</span>
<span class="p">};</span>
<span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="s">&quot;Request headers:</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">);</span>
<span class="n">print_headers</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="n">hdrs</span><span class="p">,</span> <span class="n">ARRLEN</span><span class="p">(</span><span class="n">hdrs</span><span class="p">));</span>
<span class="n">rv</span> <span class="o">=</span> <span class="n">nghttp2_submit_request</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">session</span><span class="p">,</span> <span class="nb">NULL</span><span class="p">,</span>
<span class="n">hdrs</span><span class="p">,</span> <span class="n">ARRLEN</span><span class="p">(</span><span class="n">hdrs</span><span class="p">),</span> <span class="nb">NULL</span><span class="p">,</span> <span class="n">stream_data</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">rv</span> <span class="o">!=</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">errx</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="s">&quot;Could not submit HTTP request: %s&quot;</span><span class="p">,</span> <span class="n">nghttp2_strerror</span><span class="p">(</span><span class="n">rv</span><span class="p">));</span>
<span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
<p>We build HTTP request header fields in <tt class="docutils literal"><span class="pre">hdrs</span></tt> which is an array of
<a class="reference internal" href="apiref.html#c.nghttp2_nv" title="nghttp2_nv"><tt class="xref c c-type docutils literal"><span class="pre">nghttp2_nv</span></tt></a>. There are 4 header fields to be sent: <tt class="docutils literal"><span class="pre">:method</span></tt>,
<tt class="docutils literal"><span class="pre">:scheme</span></tt>, <tt class="docutils literal"><span class="pre">:authority</span></tt> and <tt class="docutils literal"><span class="pre">:path</span></tt>. To queue this HTTP request,
we use <a class="reference internal" href="apiref.html#c.nghttp2_submit_request" title="nghttp2_submit_request"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_submit_request()</span></tt></a> function. The <tt class="xref c c-func docutils literal"><span class="pre">stream_data()</span></tt> is
passed in <em>stream_user_data</em> parameter. It is used in nghttp2
callbacks which we&#8217;ll describe about later.</p>
<p>The next bufferevent callback is <tt class="docutils literal"><span class="pre">readcb()</span></tt>, which is invoked when
data is available to read in the bufferevent input buffer:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">static</span> <span class="kt">void</span> <span class="nf">readcb</span><span class="p">(</span><span class="k">struct</span> <span class="n">bufferevent</span> <span class="o">*</span><span class="n">bev</span><span class="p">,</span> <span class="kt">void</span> <span class="o">*</span><span class="n">ptr</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">ptr</span><span class="p">;</span>
<span class="kt">int</span> <span class="n">rv</span><span class="p">;</span>
<span class="k">struct</span> <span class="n">evbuffer</span> <span class="o">*</span><span class="n">input</span> <span class="o">=</span> <span class="n">bufferevent_get_input</span><span class="p">(</span><span class="n">bev</span><span class="p">);</span>
<span class="kt">size_t</span> <span class="n">datalen</span> <span class="o">=</span> <span class="n">evbuffer_get_length</span><span class="p">(</span><span class="n">input</span><span class="p">);</span>
<span class="kt">unsigned</span> <span class="kt">char</span> <span class="o">*</span><span class="n">data</span> <span class="o">=</span> <span class="n">evbuffer_pullup</span><span class="p">(</span><span class="n">input</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">);</span>
<span class="n">rv</span> <span class="o">=</span> <span class="n">nghttp2_session_mem_recv</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">session</span><span class="p">,</span> <span class="n">data</span><span class="p">,</span> <span class="n">datalen</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">rv</span> <span class="o">&lt;</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">warnx</span><span class="p">(</span><span class="s">&quot;Fatal error: %s&quot;</span><span class="p">,</span> <span class="n">nghttp2_strerror</span><span class="p">(</span><span class="n">rv</span><span class="p">));</span>
<span class="n">delete_http2_session_data</span><span class="p">(</span><span class="n">session_data</span><span class="p">);</span>
<span class="k">return</span><span class="p">;</span>
<span class="p">}</span>
<span class="n">evbuffer_drain</span><span class="p">(</span><span class="n">input</span><span class="p">,</span> <span class="n">rv</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">session_send</span><span class="p">(</span><span class="n">session_data</span><span class="p">)</span> <span class="o">!=</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">delete_http2_session_data</span><span class="p">(</span><span class="n">session_data</span><span class="p">);</span>
<span class="k">return</span><span class="p">;</span>
<span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
<p>In this function, we feed all unprocessed, received data to nghttp2
session object using <a class="reference internal" href="apiref.html#c.nghttp2_session_mem_recv" title="nghttp2_session_mem_recv"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_session_mem_recv()</span></tt></a> function. The
<a class="reference internal" href="apiref.html#c.nghttp2_session_mem_recv" title="nghttp2_session_mem_recv"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_session_mem_recv()</span></tt></a> processes the received data and may
invoke nghttp2 callbacks and also queue frames. Since there may be
pending frames, we call <tt class="docutils literal"><span class="pre">session_send()</span></tt> function to send those
frames. The <tt class="docutils literal"><span class="pre">session_send()</span></tt> function is defined as follows:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">static</span> <span class="kt">int</span> <span class="nf">session_send</span><span class="p">(</span><span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="kt">int</span> <span class="n">rv</span><span class="p">;</span>
<span class="n">rv</span> <span class="o">=</span> <span class="n">nghttp2_session_send</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">session</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">rv</span> <span class="o">!=</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">warnx</span><span class="p">(</span><span class="s">&quot;Fatal error: %s&quot;</span><span class="p">,</span> <span class="n">nghttp2_strerror</span><span class="p">(</span><span class="n">rv</span><span class="p">));</span>
<span class="k">return</span> <span class="o">-</span><span class="mi">1</span><span class="p">;</span>
<span class="p">}</span>
<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<p>The <a class="reference internal" href="apiref.html#c.nghttp2_session_send" title="nghttp2_session_send"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_session_send()</span></tt></a> function serializes the frame into wire
format and call <a class="reference internal" href="apiref.html#c.nghttp2_session_callbacks.send_callback" title="nghttp2_session_callbacks.send_callback"><tt class="xref c c-member docutils literal"><span class="pre">nghttp2_session_callbacks.send_callback</span></tt></a> with
it. We set <tt class="docutils literal"><span class="pre">send_callback()</span></tt> function to
<a class="reference internal" href="apiref.html#c.nghttp2_session_callbacks.send_callback" title="nghttp2_session_callbacks.send_callback"><tt class="xref c c-member docutils literal"><span class="pre">nghttp2_session_callbacks.send_callback</span></tt></a> in
<tt class="docutils literal"><span class="pre">initialize_nghttp2_session()</span></tt> function described earlier. It is
defined as follows:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">static</span> <span class="kt">ssize_t</span> <span class="nf">send_callback</span><span class="p">(</span><span class="n">nghttp2_session</span> <span class="o">*</span><span class="n">session</span><span class="p">,</span>
<span class="k">const</span> <span class="kt">uint8_t</span> <span class="o">*</span><span class="n">data</span><span class="p">,</span> <span class="kt">size_t</span> <span class="n">length</span><span class="p">,</span>
<span class="kt">int</span> <span class="n">flags</span><span class="p">,</span> <span class="kt">void</span> <span class="o">*</span><span class="n">user_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">user_data</span><span class="p">;</span>
<span class="k">struct</span> <span class="n">bufferevent</span> <span class="o">*</span><span class="n">bev</span> <span class="o">=</span> <span class="n">session_data</span><span class="o">-&gt;</span><span class="n">bev</span><span class="p">;</span>
<span class="n">bufferevent_write</span><span class="p">(</span><span class="n">bev</span><span class="p">,</span> <span class="n">data</span><span class="p">,</span> <span class="n">length</span><span class="p">);</span>
<span class="k">return</span> <span class="n">length</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<p>Since we use bufferevent to abstract network I/O, we just write the
data to the bufferevent object. Note that <a class="reference internal" href="apiref.html#c.nghttp2_session_send" title="nghttp2_session_send"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_session_send()</span></tt></a>
continues to write all frames queued so far. If we were writing the
data to the non-blocking socket directly using <tt class="docutils literal"><span class="pre">write()</span></tt> system call
in the <a class="reference internal" href="apiref.html#c.nghttp2_session_callbacks.send_callback" title="nghttp2_session_callbacks.send_callback"><tt class="xref c c-member docutils literal"><span class="pre">nghttp2_session_callbacks.send_callback</span></tt></a>, we will
surely get <tt class="docutils literal"><span class="pre">EAGAIN</span></tt> or <tt class="docutils literal"><span class="pre">EWOULDBLOCK</span></tt> since the socket has limited
send buffer. If that happens, we can return
<a class="reference internal" href="apiref.html#c.NGHTTP2_ERR_WOULDBLOCK" title="NGHTTP2_ERR_WOULDBLOCK"><tt class="xref c c-macro docutils literal"><span class="pre">NGHTTP2_ERR_WOULDBLOCK</span></tt></a> to signal the nghttp2 library to stop
sending further data. But writing to the bufferevent, we have to
regulate the amount data to be buffered by ourselves to avoid possible
huge memory consumption. In this example client, we do not limit
anything. To see how to regulate the amount of buffered data, see the
<tt class="docutils literal"><span class="pre">send_callback()</span></tt> in the server tutorial.</p>
<p>The third bufferevent callback is <tt class="docutils literal"><span class="pre">writecb()</span></tt>, which is invoked when
all data written in the bufferevent output buffer have been sent:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">static</span> <span class="kt">void</span> <span class="nf">writecb</span><span class="p">(</span><span class="k">struct</span> <span class="n">bufferevent</span> <span class="o">*</span><span class="n">bev</span><span class="p">,</span> <span class="kt">void</span> <span class="o">*</span><span class="n">ptr</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">ptr</span><span class="p">;</span>
<span class="k">if</span><span class="p">(</span><span class="n">nghttp2_session_want_read</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">session</span><span class="p">)</span> <span class="o">==</span> <span class="mi">0</span> <span class="o">&amp;&amp;</span>
<span class="n">nghttp2_session_want_write</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">session</span><span class="p">)</span> <span class="o">==</span> <span class="mi">0</span> <span class="o">&amp;&amp;</span>
<span class="n">evbuffer_get_length</span><span class="p">(</span><span class="n">bufferevent_get_output</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">bev</span><span class="p">))</span> <span class="o">==</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">delete_http2_session_data</span><span class="p">(</span><span class="n">session_data</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
<p>As described earlier, we just write off all data in <tt class="xref c c-func docutils literal"><span class="pre">send_callback()</span></tt>,
we have no data to write in this function. All we have to do is check
we have to drop connection or not. The nghttp2 session object keeps
track of reception and transmission of GOAWAY frame and other error
conditions as well. Using these information, nghttp2 session object
will tell whether the connection should be dropped or not. More
specifically, both <a class="reference internal" href="apiref.html#c.nghttp2_session_want_read" title="nghttp2_session_want_read"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_session_want_read()</span></tt></a> and
<a class="reference internal" href="apiref.html#c.nghttp2_session_want_write" title="nghttp2_session_want_write"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_session_want_write()</span></tt></a> return 0, we have no business in the
connection. But since we are using bufferevent and its deferred
callback option, the bufferevent output buffer may contain the pending
data when the <tt class="docutils literal"><span class="pre">writecb()</span></tt> is called. To handle this situation, we
also check whether the output buffer is empty or not. If these
conditions are met, we drop connection.</p>
<p>We have already described about nghttp2 callback <tt class="docutils literal"><span class="pre">send_callback()</span></tt>.
Let&#8217;s describe remaining nghttp2 callbacks we setup in
<tt class="docutils literal"><span class="pre">initialize_nghttp2_setup()</span></tt> function.</p>
<p>The <tt class="xref c c-func docutils literal"><span class="pre">before_frame_send_callback()</span></tt> function is invoked when a frame is
about to be sent:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">static</span> <span class="kt">int</span> <span class="nf">before_frame_send_callback</span>
<span class="p">(</span><span class="n">nghttp2_session</span> <span class="o">*</span><span class="n">session</span><span class="p">,</span> <span class="k">const</span> <span class="n">nghttp2_frame</span> <span class="o">*</span><span class="n">frame</span><span class="p">,</span> <span class="kt">void</span> <span class="o">*</span><span class="n">user_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">user_data</span><span class="p">;</span>
<span class="n">http2_stream_data</span> <span class="o">*</span><span class="n">stream_data</span><span class="p">;</span>
<span class="k">if</span><span class="p">(</span><span class="n">frame</span><span class="o">-&gt;</span><span class="n">hd</span><span class="p">.</span><span class="n">type</span> <span class="o">==</span> <span class="n">NGHTTP2_HEADERS</span> <span class="o">&amp;&amp;</span>
<span class="n">frame</span><span class="o">-&gt;</span><span class="n">headers</span><span class="p">.</span><span class="n">cat</span> <span class="o">==</span> <span class="n">NGHTTP2_HCAT_REQUEST</span><span class="p">)</span> <span class="p">{</span>
<span class="n">stream_data</span> <span class="o">=</span>
<span class="p">(</span><span class="n">http2_stream_data</span><span class="o">*</span><span class="p">)</span><span class="n">nghttp2_session_get_stream_user_data</span>
<span class="p">(</span><span class="n">session</span><span class="p">,</span> <span class="n">frame</span><span class="o">-&gt;</span><span class="n">hd</span><span class="p">.</span><span class="n">stream_id</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">stream_data</span> <span class="o">==</span> <span class="n">session_data</span><span class="o">-&gt;</span><span class="n">stream_data</span><span class="p">)</span> <span class="p">{</span>
<span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">stream_id</span> <span class="o">=</span> <span class="n">frame</span><span class="o">-&gt;</span><span class="n">hd</span><span class="p">.</span><span class="n">stream_id</span><span class="p">;</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<p>Remember that we have not get stream ID when we submit HTTP request
using <a class="reference internal" href="apiref.html#c.nghttp2_submit_request" title="nghttp2_submit_request"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_submit_request()</span></tt></a>. Since nghttp2 library reorders the
request based on priority and stream ID must be monotonically
increased, the stream ID is not assigned just before transmission.
The one of the purpose of this callback is get the stream ID assigned
to the frame. First we check that the frame is HEADERS frame. Since
HEADERS has several meanings in HTTP/2, we check that it is request
HEADERS (which means that the first HEADERS frame to create a stream).
The assigned stream ID is <tt class="docutils literal"><span class="pre">frame-&gt;hd.stream_id</span></tt>. Recall that we
passed <tt class="docutils literal"><span class="pre">stream_data</span></tt> in the <em>stream_user_data</em> parameter of
<a class="reference internal" href="apiref.html#c.nghttp2_submit_request" title="nghttp2_submit_request"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_submit_request()</span></tt></a> function. We can get it using
<a class="reference internal" href="apiref.html#c.nghttp2_session_get_stream_user_data" title="nghttp2_session_get_stream_user_data"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_session_get_stream_user_data()</span></tt></a> function. To really sure that
this HEADERS frame is the request HEADERS we have queued, we check
that <tt class="docutils literal"><span class="pre">session_data-&gt;stream_data</span></tt> and <tt class="docutils literal"><span class="pre">stream_data</span></tt> returned from
<a class="reference internal" href="apiref.html#c.nghttp2_session_get_stream_user_data" title="nghttp2_session_get_stream_user_data"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_session_get_stream_user_data()</span></tt></a> are pointing the same
location. In this example program, we just only uses 1 stream, it is
unnecessary to compare them, but real applications surely deal with
multiple streams, and <em>stream_user_data</em> is very handy to identify
which HEADERS we are seeing in the callback. Therefore we just show
how to use it here.</p>
<p>Each request header name/value pair is emitted via
<tt class="docutils literal"><span class="pre">on_header_callback</span></tt> function:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">static</span> <span class="kt">int</span> <span class="nf">on_header_callback</span><span class="p">(</span><span class="n">nghttp2_session</span> <span class="o">*</span><span class="n">session</span><span class="p">,</span>
<span class="k">const</span> <span class="n">nghttp2_frame</span> <span class="o">*</span><span class="n">frame</span><span class="p">,</span>
<span class="k">const</span> <span class="kt">uint8_t</span> <span class="o">*</span><span class="n">name</span><span class="p">,</span> <span class="kt">size_t</span> <span class="n">namelen</span><span class="p">,</span>
<span class="k">const</span> <span class="kt">uint8_t</span> <span class="o">*</span><span class="n">value</span><span class="p">,</span> <span class="kt">size_t</span> <span class="n">valuelen</span><span class="p">,</span>
<span class="kt">uint8_t</span> <span class="n">flags</span><span class="p">,</span>
<span class="kt">void</span> <span class="o">*</span><span class="n">user_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">user_data</span><span class="p">;</span>
<span class="k">switch</span><span class="p">(</span><span class="n">frame</span><span class="o">-&gt;</span><span class="n">hd</span><span class="p">.</span><span class="n">type</span><span class="p">)</span> <span class="p">{</span>
<span class="k">case</span> <span class="n">NGHTTP2_HEADERS</span>:
<span class="k">if</span><span class="p">(</span><span class="n">frame</span><span class="o">-&gt;</span><span class="n">headers</span><span class="p">.</span><span class="n">cat</span> <span class="o">==</span> <span class="n">NGHTTP2_HCAT_RESPONSE</span> <span class="o">&amp;&amp;</span>
<span class="n">session_data</span><span class="o">-&gt;</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">stream_id</span> <span class="o">==</span> <span class="n">frame</span><span class="o">-&gt;</span><span class="n">hd</span><span class="p">.</span><span class="n">stream_id</span><span class="p">)</span> <span class="p">{</span>
<span class="cm">/* Print response headers for the initiated request. */</span>
<span class="n">print_header</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="n">name</span><span class="p">,</span> <span class="n">namelen</span><span class="p">,</span> <span class="n">value</span><span class="p">,</span> <span class="n">valuelen</span><span class="p">);</span>
<span class="k">break</span><span class="p">;</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<p>In this turotial, we just print the name/value pair.</p>
<p>After all name/value pairs are emitted for a frame,
<tt class="docutils literal"><span class="pre">on_frame_recv_callback</span></tt> function is called:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">static</span> <span class="kt">int</span> <span class="nf">on_frame_recv_callback</span><span class="p">(</span><span class="n">nghttp2_session</span> <span class="o">*</span><span class="n">session</span><span class="p">,</span>
<span class="k">const</span> <span class="n">nghttp2_frame</span> <span class="o">*</span><span class="n">frame</span><span class="p">,</span> <span class="kt">void</span> <span class="o">*</span><span class="n">user_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">user_data</span><span class="p">;</span>
<span class="k">switch</span><span class="p">(</span><span class="n">frame</span><span class="o">-&gt;</span><span class="n">hd</span><span class="p">.</span><span class="n">type</span><span class="p">)</span> <span class="p">{</span>
<span class="k">case</span> <span class="n">NGHTTP2_HEADERS</span>:
<span class="k">if</span><span class="p">(</span><span class="n">frame</span><span class="o">-&gt;</span><span class="n">headers</span><span class="p">.</span><span class="n">cat</span> <span class="o">==</span> <span class="n">NGHTTP2_HCAT_RESPONSE</span> <span class="o">&amp;&amp;</span>
<span class="n">session_data</span><span class="o">-&gt;</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">stream_id</span> <span class="o">==</span> <span class="n">frame</span><span class="o">-&gt;</span><span class="n">hd</span><span class="p">.</span><span class="n">stream_id</span><span class="p">)</span> <span class="p">{</span>
<span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="s">&quot;All headers received</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">);</span>
<span class="p">}</span>
<span class="k">break</span><span class="p">;</span>
<span class="p">}</span>
<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<p>In this tutorial, we are just interested in the HTTP response
HEADERS. We check te frame type and its category (it should be
<a class="reference internal" href="apiref.html#c.NGHTTP2_HCAT_RESPONSE" title="NGHTTP2_HCAT_RESPONSE"><tt class="xref c c-macro docutils literal"><span class="pre">NGHTTP2_HCAT_RESPONSE</span></tt></a> for HTTP response HEADERS). Also check
its stream ID.</p>
<p>The <tt class="docutils literal"><span class="pre">on_data_chunk_recv_callback()</span></tt> function is invoked when a chunk
of data is received from the remote peer:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">static</span> <span class="kt">int</span> <span class="nf">on_data_chunk_recv_callback</span><span class="p">(</span><span class="n">nghttp2_session</span> <span class="o">*</span><span class="n">session</span><span class="p">,</span> <span class="kt">uint8_t</span> <span class="n">flags</span><span class="p">,</span>
<span class="kt">int32_t</span> <span class="n">stream_id</span><span class="p">,</span>
<span class="k">const</span> <span class="kt">uint8_t</span> <span class="o">*</span><span class="n">data</span><span class="p">,</span> <span class="kt">size_t</span> <span class="n">len</span><span class="p">,</span>
<span class="kt">void</span> <span class="o">*</span><span class="n">user_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">user_data</span><span class="p">;</span>
<span class="k">if</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">stream_id</span> <span class="o">==</span> <span class="n">stream_id</span><span class="p">)</span> <span class="p">{</span>
<span class="n">fwrite</span><span class="p">(</span><span class="n">data</span><span class="p">,</span> <span class="n">len</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="n">stdout</span><span class="p">);</span>
<span class="p">}</span>
<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<p>In our case, a chunk of data is response body. After checking stream
ID, we just write the recieved data to the stdout. Note that the
output in the terminal may be corrupted if the response body contains
some binary data.</p>
<p>The <tt class="docutils literal"><span class="pre">on_stream_close_callback()</span></tt> function is invoked when the stream
is about to close:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">static</span> <span class="kt">int</span> <span class="nf">on_stream_close_callback</span><span class="p">(</span><span class="n">nghttp2_session</span> <span class="o">*</span><span class="n">session</span><span class="p">,</span>
<span class="kt">int32_t</span> <span class="n">stream_id</span><span class="p">,</span>
<span class="n">nghttp2_error_code</span> <span class="n">error_code</span><span class="p">,</span>
<span class="kt">void</span> <span class="o">*</span><span class="n">user_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">user_data</span><span class="p">;</span>
<span class="kt">int</span> <span class="n">rv</span><span class="p">;</span>
<span class="k">if</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">stream_id</span> <span class="o">==</span> <span class="n">stream_id</span><span class="p">)</span> <span class="p">{</span>
<span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="s">&quot;Stream %d closed with error_code=%d</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">,</span>
<span class="n">stream_id</span><span class="p">,</span> <span class="n">error_code</span><span class="p">);</span>
<span class="n">rv</span> <span class="o">=</span> <span class="n">nghttp2_session_terminate_session</span><span class="p">(</span><span class="n">session</span><span class="p">,</span> <span class="n">NGHTTP2_NO_ERROR</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">rv</span> <span class="o">!=</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="k">return</span> <span class="n">NGHTTP2_ERR_CALLBACK_FAILURE</span><span class="p">;</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<p>If the stream ID matches the one we initiated, it means that its
stream is going to be closed. Since we have finished to get the
resource we want (or the stream was reset by RST_STREAM from the
remote peer), we call <a class="reference internal" href="apiref.html#c.nghttp2_session_terminate_session" title="nghttp2_session_terminate_session"><tt class="xref c c-func docutils literal"><span class="pre">nghttp2_session_terminate_session()</span></tt></a> to
commencing the closure of the HTTP/2 session gracefully. If you have
some data associated for the stream to be closed, you may delete it
here.</p>
<div class="section" id="libevent-client-c">
<h2>libevent-client.c<a class="headerlink" href="#libevent-client-c" title="Permalink to this headline"></a></h2>
<div class="highlight-c"><div class="highlight"><pre><span class="cm">/*</span>
<span class="cm"> * nghttp2 - HTTP/2 C Library</span>
<span class="cm"> *</span>
<span class="cm"> * Copyright (c) 2013 Tatsuhiro Tsujikawa</span>
<span class="cm"> *</span>
<span class="cm"> * Permission is hereby granted, free of charge, to any person obtaining</span>
<span class="cm"> * a copy of this software and associated documentation files (the</span>
<span class="cm"> * &quot;Software&quot;), to deal in the Software without restriction, including</span>
<span class="cm"> * without limitation the rights to use, copy, modify, merge, publish,</span>
<span class="cm"> * distribute, sublicense, and/or sell copies of the Software, and to</span>
<span class="cm"> * permit persons to whom the Software is furnished to do so, subject to</span>
<span class="cm"> * the following conditions:</span>
<span class="cm"> *</span>
<span class="cm"> * The above copyright notice and this permission notice shall be</span>
<span class="cm"> * included in all copies or substantial portions of the Software.</span>
<span class="cm"> *</span>
<span class="cm"> * THE SOFTWARE IS PROVIDED &quot;AS IS&quot;, WITHOUT WARRANTY OF ANY KIND,</span>
<span class="cm"> * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF</span>
<span class="cm"> * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND</span>
<span class="cm"> * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE</span>
<span class="cm"> * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION</span>
<span class="cm"> * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION</span>
<span class="cm"> * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.</span>
<span class="cm"> */</span>
<span class="cp">#include &lt;sys/types.h&gt;</span>
<span class="cp">#include &lt;unistd.h&gt;</span>
<span class="cp">#include &lt;sys/socket.h&gt;</span>
<span class="cp">#include &lt;netinet/in.h&gt;</span>
<span class="cp">#include &lt;netinet/tcp.h&gt;</span>
<span class="cp">#include &lt;err.h&gt;</span>
<span class="cp">#include &lt;signal.h&gt;</span>
<span class="cp">#include &lt;openssl/ssl.h&gt;</span>
<span class="cp">#include &lt;openssl/err.h&gt;</span>
<span class="cp">#include &lt;event.h&gt;</span>
<span class="cp">#include &lt;event2/event.h&gt;</span>
<span class="cp">#include &lt;event2/bufferevent_ssl.h&gt;</span>
<span class="cp">#include &lt;event2/dns.h&gt;</span>
<span class="cp">#include &lt;nghttp2/nghttp2.h&gt;</span>
<span class="cp">#include &quot;http-parser/http_parser.h&quot;</span>
<span class="cp">#define ARRLEN(x) (sizeof(x)/sizeof(x[0]))</span>
<span class="k">typedef</span> <span class="k">struct</span> <span class="p">{</span>
<span class="cm">/* The NULL-terminated URI string to retreive. */</span>
<span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">uri</span><span class="p">;</span>
<span class="cm">/* Parsed result of the |uri| */</span>
<span class="k">struct</span> <span class="n">http_parser_url</span> <span class="o">*</span><span class="n">u</span><span class="p">;</span>
<span class="cm">/* The authroity portion of the |uri|, not NULL-terminated */</span>
<span class="kt">char</span> <span class="o">*</span><span class="n">authority</span><span class="p">;</span>
<span class="cm">/* The path portion of the |uri|, including query, not</span>
<span class="cm"> NULL-terminated */</span>
<span class="kt">char</span> <span class="o">*</span><span class="n">path</span><span class="p">;</span>
<span class="cm">/* The length of the |authority| */</span>
<span class="kt">size_t</span> <span class="n">authoritylen</span><span class="p">;</span>
<span class="cm">/* The length of the |path| */</span>
<span class="kt">size_t</span> <span class="n">pathlen</span><span class="p">;</span>
<span class="cm">/* The stream ID of this stream */</span>
<span class="kt">int32_t</span> <span class="n">stream_id</span><span class="p">;</span>
<span class="p">}</span> <span class="n">http2_stream_data</span><span class="p">;</span>
<span class="k">typedef</span> <span class="k">struct</span> <span class="p">{</span>
<span class="n">nghttp2_session</span> <span class="o">*</span><span class="n">session</span><span class="p">;</span>
<span class="k">struct</span> <span class="n">evdns_base</span> <span class="o">*</span><span class="n">dnsbase</span><span class="p">;</span>
<span class="k">struct</span> <span class="n">bufferevent</span> <span class="o">*</span><span class="n">bev</span><span class="p">;</span>
<span class="n">http2_stream_data</span> <span class="o">*</span><span class="n">stream_data</span><span class="p">;</span>
<span class="p">}</span> <span class="n">http2_session_data</span><span class="p">;</span>
<span class="k">static</span> <span class="n">http2_stream_data</span><span class="o">*</span> <span class="nf">create_http2_stream_data</span><span class="p">(</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">uri</span><span class="p">,</span>
<span class="k">struct</span> <span class="n">http_parser_url</span> <span class="o">*</span><span class="n">u</span><span class="p">)</span>
<span class="p">{</span>
<span class="cm">/* MAX 5 digits (max 65535) + 1 &#39;:&#39; + 1 NULL (because of snprintf) */</span>
<span class="kt">size_t</span> <span class="n">extra</span> <span class="o">=</span> <span class="mi">7</span><span class="p">;</span>
<span class="n">http2_stream_data</span> <span class="o">*</span><span class="n">stream_data</span> <span class="o">=</span> <span class="n">malloc</span><span class="p">(</span><span class="k">sizeof</span><span class="p">(</span><span class="n">http2_stream_data</span><span class="p">));</span>
<span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">uri</span> <span class="o">=</span> <span class="n">uri</span><span class="p">;</span>
<span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">u</span> <span class="o">=</span> <span class="n">u</span><span class="p">;</span>
<span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">stream_id</span> <span class="o">=</span> <span class="o">-</span><span class="mi">1</span><span class="p">;</span>
<span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">authoritylen</span> <span class="o">=</span> <span class="n">u</span><span class="o">-&gt;</span><span class="n">field_data</span><span class="p">[</span><span class="n">UF_HOST</span><span class="p">].</span><span class="n">len</span><span class="p">;</span>
<span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">authority</span> <span class="o">=</span> <span class="n">malloc</span><span class="p">(</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">authoritylen</span> <span class="o">+</span> <span class="n">extra</span><span class="p">);</span>
<span class="n">memcpy</span><span class="p">(</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">authority</span><span class="p">,</span>
<span class="o">&amp;</span><span class="n">uri</span><span class="p">[</span><span class="n">u</span><span class="o">-&gt;</span><span class="n">field_data</span><span class="p">[</span><span class="n">UF_HOST</span><span class="p">].</span><span class="n">off</span><span class="p">],</span> <span class="n">u</span><span class="o">-&gt;</span><span class="n">field_data</span><span class="p">[</span><span class="n">UF_HOST</span><span class="p">].</span><span class="n">len</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">u</span><span class="o">-&gt;</span><span class="n">field_set</span> <span class="o">&amp;</span> <span class="p">(</span><span class="mi">1</span> <span class="o">&lt;&lt;</span> <span class="n">UF_PORT</span><span class="p">))</span> <span class="p">{</span>
<span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">authoritylen</span> <span class="o">+=</span>
<span class="n">snprintf</span><span class="p">(</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">authority</span> <span class="o">+</span> <span class="n">u</span><span class="o">-&gt;</span><span class="n">field_data</span><span class="p">[</span><span class="n">UF_HOST</span><span class="p">].</span><span class="n">len</span><span class="p">,</span> <span class="n">extra</span><span class="p">,</span>
<span class="s">&quot;:%u&quot;</span><span class="p">,</span> <span class="n">u</span><span class="o">-&gt;</span><span class="n">port</span><span class="p">);</span>
<span class="p">}</span>
<span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">pathlen</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
<span class="k">if</span><span class="p">(</span><span class="n">u</span><span class="o">-&gt;</span><span class="n">field_set</span> <span class="o">&amp;</span> <span class="p">(</span><span class="mi">1</span> <span class="o">&lt;&lt;</span> <span class="n">UF_PATH</span><span class="p">))</span> <span class="p">{</span>
<span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">pathlen</span> <span class="o">=</span> <span class="n">u</span><span class="o">-&gt;</span><span class="n">field_data</span><span class="p">[</span><span class="n">UF_PATH</span><span class="p">].</span><span class="n">len</span><span class="p">;</span>
<span class="p">}</span>
<span class="k">if</span><span class="p">(</span><span class="n">u</span><span class="o">-&gt;</span><span class="n">field_set</span> <span class="o">&amp;</span> <span class="p">(</span><span class="mi">1</span> <span class="o">&lt;&lt;</span> <span class="n">UF_QUERY</span><span class="p">))</span> <span class="p">{</span>
<span class="cm">/* +1 for &#39;?&#39; character */</span>
<span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">pathlen</span> <span class="o">+=</span> <span class="n">u</span><span class="o">-&gt;</span><span class="n">field_data</span><span class="p">[</span><span class="n">UF_QUERY</span><span class="p">].</span><span class="n">len</span> <span class="o">+</span> <span class="mi">1</span><span class="p">;</span>
<span class="p">}</span>
<span class="k">if</span><span class="p">(</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">pathlen</span> <span class="o">&gt;</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">path</span> <span class="o">=</span> <span class="n">malloc</span><span class="p">(</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">pathlen</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">u</span><span class="o">-&gt;</span><span class="n">field_set</span> <span class="o">&amp;</span> <span class="p">(</span><span class="mi">1</span> <span class="o">&lt;&lt;</span> <span class="n">UF_PATH</span><span class="p">))</span> <span class="p">{</span>
<span class="n">memcpy</span><span class="p">(</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">path</span><span class="p">,</span>
<span class="o">&amp;</span><span class="n">uri</span><span class="p">[</span><span class="n">u</span><span class="o">-&gt;</span><span class="n">field_data</span><span class="p">[</span><span class="n">UF_PATH</span><span class="p">].</span><span class="n">off</span><span class="p">],</span> <span class="n">u</span><span class="o">-&gt;</span><span class="n">field_data</span><span class="p">[</span><span class="n">UF_PATH</span><span class="p">].</span><span class="n">len</span><span class="p">);</span>
<span class="p">}</span>
<span class="k">if</span><span class="p">(</span><span class="n">u</span><span class="o">-&gt;</span><span class="n">field_set</span> <span class="o">&amp;</span> <span class="p">(</span><span class="mi">1</span> <span class="o">&lt;&lt;</span> <span class="n">UF_QUERY</span><span class="p">))</span> <span class="p">{</span>
<span class="n">memcpy</span><span class="p">(</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">path</span> <span class="o">+</span> <span class="n">u</span><span class="o">-&gt;</span><span class="n">field_data</span><span class="p">[</span><span class="n">UF_PATH</span><span class="p">].</span><span class="n">len</span> <span class="o">+</span> <span class="mi">1</span><span class="p">,</span>
<span class="o">&amp;</span><span class="n">uri</span><span class="p">[</span><span class="n">u</span><span class="o">-&gt;</span><span class="n">field_data</span><span class="p">[</span><span class="n">UF_QUERY</span><span class="p">].</span><span class="n">off</span><span class="p">],</span> <span class="n">u</span><span class="o">-&gt;</span><span class="n">field_data</span><span class="p">[</span><span class="n">UF_QUERY</span><span class="p">].</span><span class="n">len</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
<span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">path</span> <span class="o">=</span> <span class="nb">NULL</span><span class="p">;</span>
<span class="p">}</span>
<span class="k">return</span> <span class="n">stream_data</span><span class="p">;</span>
<span class="p">}</span>
<span class="k">static</span> <span class="kt">void</span> <span class="nf">delete_http2_stream_data</span><span class="p">(</span><span class="n">http2_stream_data</span> <span class="o">*</span><span class="n">stream_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">free</span><span class="p">(</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">path</span><span class="p">);</span>
<span class="n">free</span><span class="p">(</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">authority</span><span class="p">);</span>
<span class="n">free</span><span class="p">(</span><span class="n">stream_data</span><span class="p">);</span>
<span class="p">}</span>
<span class="cm">/* Initializes |session_data| */</span>
<span class="k">static</span> <span class="n">http2_session_data</span> <span class="o">*</span><span class="nf">create_http2_session_data</span><span class="p">(</span><span class="k">struct</span> <span class="n">event_base</span> <span class="o">*</span><span class="n">evbase</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="n">malloc</span><span class="p">(</span><span class="k">sizeof</span><span class="p">(</span><span class="n">http2_session_data</span><span class="p">));</span>
<span class="n">memset</span><span class="p">(</span><span class="n">session_data</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="k">sizeof</span><span class="p">(</span><span class="n">http2_session_data</span><span class="p">));</span>
<span class="n">session_data</span><span class="o">-&gt;</span><span class="n">dnsbase</span> <span class="o">=</span> <span class="n">evdns_base_new</span><span class="p">(</span><span class="n">evbase</span><span class="p">,</span> <span class="mi">1</span><span class="p">);</span>
<span class="k">return</span> <span class="n">session_data</span><span class="p">;</span>
<span class="p">}</span>
<span class="k">static</span> <span class="kt">void</span> <span class="nf">delete_http2_session_data</span><span class="p">(</span><span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">SSL</span> <span class="o">*</span><span class="n">ssl</span> <span class="o">=</span> <span class="n">bufferevent_openssl_get_ssl</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">bev</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">ssl</span><span class="p">)</span> <span class="p">{</span>
<span class="n">SSL_shutdown</span><span class="p">(</span><span class="n">ssl</span><span class="p">);</span>
<span class="p">}</span>
<span class="n">bufferevent_free</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">bev</span><span class="p">);</span>
<span class="n">session_data</span><span class="o">-&gt;</span><span class="n">bev</span> <span class="o">=</span> <span class="nb">NULL</span><span class="p">;</span>
<span class="n">evdns_base_free</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">dnsbase</span><span class="p">,</span> <span class="mi">1</span><span class="p">);</span>
<span class="n">session_data</span><span class="o">-&gt;</span><span class="n">dnsbase</span> <span class="o">=</span> <span class="nb">NULL</span><span class="p">;</span>
<span class="n">nghttp2_session_del</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">session</span><span class="p">);</span>
<span class="n">session_data</span><span class="o">-&gt;</span><span class="n">session</span> <span class="o">=</span> <span class="nb">NULL</span><span class="p">;</span>
<span class="k">if</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">stream_data</span><span class="p">)</span> <span class="p">{</span>
<span class="n">delete_http2_stream_data</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">stream_data</span><span class="p">);</span>
<span class="n">session_data</span><span class="o">-&gt;</span><span class="n">stream_data</span> <span class="o">=</span> <span class="nb">NULL</span><span class="p">;</span>
<span class="p">}</span>
<span class="n">free</span><span class="p">(</span><span class="n">session_data</span><span class="p">);</span>
<span class="p">}</span>
<span class="k">static</span> <span class="kt">void</span> <span class="nf">print_header</span><span class="p">(</span><span class="kt">FILE</span> <span class="o">*</span><span class="n">f</span><span class="p">,</span>
<span class="k">const</span> <span class="kt">uint8_t</span> <span class="o">*</span><span class="n">name</span><span class="p">,</span> <span class="kt">size_t</span> <span class="n">namelen</span><span class="p">,</span>
<span class="k">const</span> <span class="kt">uint8_t</span> <span class="o">*</span><span class="n">value</span><span class="p">,</span> <span class="kt">size_t</span> <span class="n">valuelen</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">fwrite</span><span class="p">(</span><span class="n">name</span><span class="p">,</span> <span class="n">namelen</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="n">f</span><span class="p">);</span>
<span class="n">fprintf</span><span class="p">(</span><span class="n">f</span><span class="p">,</span> <span class="s">&quot;: &quot;</span><span class="p">);</span>
<span class="n">fwrite</span><span class="p">(</span><span class="n">value</span><span class="p">,</span> <span class="n">valuelen</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="n">f</span><span class="p">);</span>
<span class="n">fprintf</span><span class="p">(</span><span class="n">f</span><span class="p">,</span> <span class="s">&quot;</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">);</span>
<span class="p">}</span>
<span class="cm">/* Print HTTP headers to |f|. Please note that this function does not</span>
<span class="cm"> take into account that header name and value are sequence of</span>
<span class="cm"> octets, therefore they may contain non-printable characters. */</span>
<span class="k">static</span> <span class="kt">void</span> <span class="nf">print_headers</span><span class="p">(</span><span class="kt">FILE</span> <span class="o">*</span><span class="n">f</span><span class="p">,</span> <span class="n">nghttp2_nv</span> <span class="o">*</span><span class="n">nva</span><span class="p">,</span> <span class="kt">size_t</span> <span class="n">nvlen</span><span class="p">)</span>
<span class="p">{</span>
<span class="kt">size_t</span> <span class="n">i</span><span class="p">;</span>
<span class="k">for</span><span class="p">(</span><span class="n">i</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span> <span class="n">i</span> <span class="o">&lt;</span> <span class="n">nvlen</span><span class="p">;</span> <span class="o">++</span><span class="n">i</span><span class="p">)</span> <span class="p">{</span>
<span class="n">print_header</span><span class="p">(</span><span class="n">f</span><span class="p">,</span>
<span class="n">nva</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">name</span><span class="p">,</span> <span class="n">nva</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">namelen</span><span class="p">,</span>
<span class="n">nva</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">value</span><span class="p">,</span> <span class="n">nva</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">valuelen</span><span class="p">);</span>
<span class="p">}</span>
<span class="n">fprintf</span><span class="p">(</span><span class="n">f</span><span class="p">,</span> <span class="s">&quot;</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">);</span>
<span class="p">}</span>
<span class="cm">/* nghttp2_send_callback. Here we transmit the |data|, |length| bytes,</span>
<span class="cm"> to the network. Because we are using libevent bufferevent, we just</span>
<span class="cm"> write those bytes into bufferevent buffer. */</span>
<span class="k">static</span> <span class="kt">ssize_t</span> <span class="nf">send_callback</span><span class="p">(</span><span class="n">nghttp2_session</span> <span class="o">*</span><span class="n">session</span><span class="p">,</span>
<span class="k">const</span> <span class="kt">uint8_t</span> <span class="o">*</span><span class="n">data</span><span class="p">,</span> <span class="kt">size_t</span> <span class="n">length</span><span class="p">,</span>
<span class="kt">int</span> <span class="n">flags</span><span class="p">,</span> <span class="kt">void</span> <span class="o">*</span><span class="n">user_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">user_data</span><span class="p">;</span>
<span class="k">struct</span> <span class="n">bufferevent</span> <span class="o">*</span><span class="n">bev</span> <span class="o">=</span> <span class="n">session_data</span><span class="o">-&gt;</span><span class="n">bev</span><span class="p">;</span>
<span class="n">bufferevent_write</span><span class="p">(</span><span class="n">bev</span><span class="p">,</span> <span class="n">data</span><span class="p">,</span> <span class="n">length</span><span class="p">);</span>
<span class="k">return</span> <span class="n">length</span><span class="p">;</span>
<span class="p">}</span>
<span class="cm">/* nghttp2_before_frame_send_callback: Called when nghttp2 library is</span>
<span class="cm"> about to send a frame. We use this callback to get stream ID of new</span>
<span class="cm"> stream. Since HEADERS in HTTP/2 has several roles, we check that</span>
<span class="cm"> it is a HTTP request HEADERS. */</span>
<span class="k">static</span> <span class="kt">int</span> <span class="nf">before_frame_send_callback</span>
<span class="p">(</span><span class="n">nghttp2_session</span> <span class="o">*</span><span class="n">session</span><span class="p">,</span> <span class="k">const</span> <span class="n">nghttp2_frame</span> <span class="o">*</span><span class="n">frame</span><span class="p">,</span> <span class="kt">void</span> <span class="o">*</span><span class="n">user_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">user_data</span><span class="p">;</span>
<span class="n">http2_stream_data</span> <span class="o">*</span><span class="n">stream_data</span><span class="p">;</span>
<span class="k">if</span><span class="p">(</span><span class="n">frame</span><span class="o">-&gt;</span><span class="n">hd</span><span class="p">.</span><span class="n">type</span> <span class="o">==</span> <span class="n">NGHTTP2_HEADERS</span> <span class="o">&amp;&amp;</span>
<span class="n">frame</span><span class="o">-&gt;</span><span class="n">headers</span><span class="p">.</span><span class="n">cat</span> <span class="o">==</span> <span class="n">NGHTTP2_HCAT_REQUEST</span><span class="p">)</span> <span class="p">{</span>
<span class="n">stream_data</span> <span class="o">=</span>
<span class="p">(</span><span class="n">http2_stream_data</span><span class="o">*</span><span class="p">)</span><span class="n">nghttp2_session_get_stream_user_data</span>
<span class="p">(</span><span class="n">session</span><span class="p">,</span> <span class="n">frame</span><span class="o">-&gt;</span><span class="n">hd</span><span class="p">.</span><span class="n">stream_id</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">stream_data</span> <span class="o">==</span> <span class="n">session_data</span><span class="o">-&gt;</span><span class="n">stream_data</span><span class="p">)</span> <span class="p">{</span>
<span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">stream_id</span> <span class="o">=</span> <span class="n">frame</span><span class="o">-&gt;</span><span class="n">hd</span><span class="p">.</span><span class="n">stream_id</span><span class="p">;</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>
<span class="cm">/* nghttp2_on_header_callback: Called when nghttp2 library emits</span>
<span class="cm"> single header name/value pair. */</span>
<span class="k">static</span> <span class="kt">int</span> <span class="nf">on_header_callback</span><span class="p">(</span><span class="n">nghttp2_session</span> <span class="o">*</span><span class="n">session</span><span class="p">,</span>
<span class="k">const</span> <span class="n">nghttp2_frame</span> <span class="o">*</span><span class="n">frame</span><span class="p">,</span>
<span class="k">const</span> <span class="kt">uint8_t</span> <span class="o">*</span><span class="n">name</span><span class="p">,</span> <span class="kt">size_t</span> <span class="n">namelen</span><span class="p">,</span>
<span class="k">const</span> <span class="kt">uint8_t</span> <span class="o">*</span><span class="n">value</span><span class="p">,</span> <span class="kt">size_t</span> <span class="n">valuelen</span><span class="p">,</span>
<span class="kt">uint8_t</span> <span class="n">flags</span><span class="p">,</span>
<span class="kt">void</span> <span class="o">*</span><span class="n">user_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">user_data</span><span class="p">;</span>
<span class="k">switch</span><span class="p">(</span><span class="n">frame</span><span class="o">-&gt;</span><span class="n">hd</span><span class="p">.</span><span class="n">type</span><span class="p">)</span> <span class="p">{</span>
<span class="k">case</span> <span class="n">NGHTTP2_HEADERS</span>:
<span class="k">if</span><span class="p">(</span><span class="n">frame</span><span class="o">-&gt;</span><span class="n">headers</span><span class="p">.</span><span class="n">cat</span> <span class="o">==</span> <span class="n">NGHTTP2_HCAT_RESPONSE</span> <span class="o">&amp;&amp;</span>
<span class="n">session_data</span><span class="o">-&gt;</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">stream_id</span> <span class="o">==</span> <span class="n">frame</span><span class="o">-&gt;</span><span class="n">hd</span><span class="p">.</span><span class="n">stream_id</span><span class="p">)</span> <span class="p">{</span>
<span class="cm">/* Print response headers for the initiated request. */</span>
<span class="n">print_header</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="n">name</span><span class="p">,</span> <span class="n">namelen</span><span class="p">,</span> <span class="n">value</span><span class="p">,</span> <span class="n">valuelen</span><span class="p">);</span>
<span class="k">break</span><span class="p">;</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>
<span class="cm">/* nghttp2_on_begin_headers_callback: Called when nghttp2 library gets</span>
<span class="cm"> started to receive header block. */</span>
<span class="k">static</span> <span class="kt">int</span> <span class="nf">on_begin_headers_callback</span><span class="p">(</span><span class="n">nghttp2_session</span> <span class="o">*</span><span class="n">session</span><span class="p">,</span>
<span class="k">const</span> <span class="n">nghttp2_frame</span> <span class="o">*</span><span class="n">frame</span><span class="p">,</span>
<span class="kt">void</span> <span class="o">*</span><span class="n">user_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">user_data</span><span class="p">;</span>
<span class="k">switch</span><span class="p">(</span><span class="n">frame</span><span class="o">-&gt;</span><span class="n">hd</span><span class="p">.</span><span class="n">type</span><span class="p">)</span> <span class="p">{</span>
<span class="k">case</span> <span class="n">NGHTTP2_HEADERS</span>:
<span class="k">if</span><span class="p">(</span><span class="n">frame</span><span class="o">-&gt;</span><span class="n">headers</span><span class="p">.</span><span class="n">cat</span> <span class="o">==</span> <span class="n">NGHTTP2_HCAT_RESPONSE</span> <span class="o">&amp;&amp;</span>
<span class="n">session_data</span><span class="o">-&gt;</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">stream_id</span> <span class="o">==</span> <span class="n">frame</span><span class="o">-&gt;</span><span class="n">hd</span><span class="p">.</span><span class="n">stream_id</span><span class="p">)</span> <span class="p">{</span>
<span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="s">&quot;Response headers for stream ID=%d:</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">,</span>
<span class="n">frame</span><span class="o">-&gt;</span><span class="n">hd</span><span class="p">.</span><span class="n">stream_id</span><span class="p">);</span>
<span class="p">}</span>
<span class="k">break</span><span class="p">;</span>
<span class="p">}</span>
<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>
<span class="cm">/* nghttp2_on_frame_recv_callback: Called when nghttp2 library</span>
<span class="cm"> received a complete frame from the remote peer. */</span>
<span class="k">static</span> <span class="kt">int</span> <span class="nf">on_frame_recv_callback</span><span class="p">(</span><span class="n">nghttp2_session</span> <span class="o">*</span><span class="n">session</span><span class="p">,</span>
<span class="k">const</span> <span class="n">nghttp2_frame</span> <span class="o">*</span><span class="n">frame</span><span class="p">,</span> <span class="kt">void</span> <span class="o">*</span><span class="n">user_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">user_data</span><span class="p">;</span>
<span class="k">switch</span><span class="p">(</span><span class="n">frame</span><span class="o">-&gt;</span><span class="n">hd</span><span class="p">.</span><span class="n">type</span><span class="p">)</span> <span class="p">{</span>
<span class="k">case</span> <span class="n">NGHTTP2_HEADERS</span>:
<span class="k">if</span><span class="p">(</span><span class="n">frame</span><span class="o">-&gt;</span><span class="n">headers</span><span class="p">.</span><span class="n">cat</span> <span class="o">==</span> <span class="n">NGHTTP2_HCAT_RESPONSE</span> <span class="o">&amp;&amp;</span>
<span class="n">session_data</span><span class="o">-&gt;</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">stream_id</span> <span class="o">==</span> <span class="n">frame</span><span class="o">-&gt;</span><span class="n">hd</span><span class="p">.</span><span class="n">stream_id</span><span class="p">)</span> <span class="p">{</span>
<span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="s">&quot;All headers received</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">);</span>
<span class="p">}</span>
<span class="k">break</span><span class="p">;</span>
<span class="p">}</span>
<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>
<span class="cm">/* nghttp2_on_data_chunk_recv_callback: Called when DATA frame is</span>
<span class="cm"> received from the remote peer. In this implementation, if the frame</span>
<span class="cm"> is meant to the stream we initiated, print the received data in</span>
<span class="cm"> stdout, so that the user can redirect its output to the file</span>
<span class="cm"> easily. */</span>
<span class="k">static</span> <span class="kt">int</span> <span class="nf">on_data_chunk_recv_callback</span><span class="p">(</span><span class="n">nghttp2_session</span> <span class="o">*</span><span class="n">session</span><span class="p">,</span> <span class="kt">uint8_t</span> <span class="n">flags</span><span class="p">,</span>
<span class="kt">int32_t</span> <span class="n">stream_id</span><span class="p">,</span>
<span class="k">const</span> <span class="kt">uint8_t</span> <span class="o">*</span><span class="n">data</span><span class="p">,</span> <span class="kt">size_t</span> <span class="n">len</span><span class="p">,</span>
<span class="kt">void</span> <span class="o">*</span><span class="n">user_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">user_data</span><span class="p">;</span>
<span class="k">if</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">stream_id</span> <span class="o">==</span> <span class="n">stream_id</span><span class="p">)</span> <span class="p">{</span>
<span class="n">fwrite</span><span class="p">(</span><span class="n">data</span><span class="p">,</span> <span class="n">len</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="n">stdout</span><span class="p">);</span>
<span class="p">}</span>
<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>
<span class="cm">/* nghttp2_on_stream_close_callback: Called when a stream is about to</span>
<span class="cm"> closed. This example program only deals with 1 HTTP request (1</span>
<span class="cm"> stream), if it is closed, we send GOAWAY and tear down the</span>
<span class="cm"> session */</span>
<span class="k">static</span> <span class="kt">int</span> <span class="nf">on_stream_close_callback</span><span class="p">(</span><span class="n">nghttp2_session</span> <span class="o">*</span><span class="n">session</span><span class="p">,</span>
<span class="kt">int32_t</span> <span class="n">stream_id</span><span class="p">,</span>
<span class="n">nghttp2_error_code</span> <span class="n">error_code</span><span class="p">,</span>
<span class="kt">void</span> <span class="o">*</span><span class="n">user_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">user_data</span><span class="p">;</span>
<span class="kt">int</span> <span class="n">rv</span><span class="p">;</span>
<span class="k">if</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">stream_id</span> <span class="o">==</span> <span class="n">stream_id</span><span class="p">)</span> <span class="p">{</span>
<span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="s">&quot;Stream %d closed with error_code=%d</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">,</span>
<span class="n">stream_id</span><span class="p">,</span> <span class="n">error_code</span><span class="p">);</span>
<span class="n">rv</span> <span class="o">=</span> <span class="n">nghttp2_session_terminate_session</span><span class="p">(</span><span class="n">session</span><span class="p">,</span> <span class="n">NGHTTP2_NO_ERROR</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">rv</span> <span class="o">!=</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="k">return</span> <span class="n">NGHTTP2_ERR_CALLBACK_FAILURE</span><span class="p">;</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>
<span class="cm">/* NPN TLS extension client callback. We check that server advertised</span>
<span class="cm"> the HTTP/2 protocol the nghttp2 library supports. If not, exit</span>
<span class="cm"> the program. */</span>
<span class="k">static</span> <span class="kt">int</span> <span class="nf">select_next_proto_cb</span><span class="p">(</span><span class="n">SSL</span><span class="o">*</span> <span class="n">ssl</span><span class="p">,</span>
<span class="kt">unsigned</span> <span class="kt">char</span> <span class="o">**</span><span class="n">out</span><span class="p">,</span> <span class="kt">unsigned</span> <span class="kt">char</span> <span class="o">*</span><span class="n">outlen</span><span class="p">,</span>
<span class="k">const</span> <span class="kt">unsigned</span> <span class="kt">char</span> <span class="o">*</span><span class="n">in</span><span class="p">,</span> <span class="kt">unsigned</span> <span class="kt">int</span> <span class="n">inlen</span><span class="p">,</span>
<span class="kt">void</span> <span class="o">*</span><span class="n">arg</span><span class="p">)</span>
<span class="p">{</span>
<span class="k">if</span><span class="p">(</span><span class="n">nghttp2_select_next_protocol</span><span class="p">(</span><span class="n">out</span><span class="p">,</span> <span class="n">outlen</span><span class="p">,</span> <span class="n">in</span><span class="p">,</span> <span class="n">inlen</span><span class="p">)</span> <span class="o">&lt;=</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">errx</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="s">&quot;Server did not advertise &quot;</span> <span class="n">NGHTTP2_PROTO_VERSION_ID</span><span class="p">);</span>
<span class="p">}</span>
<span class="k">return</span> <span class="n">SSL_TLSEXT_ERR_OK</span><span class="p">;</span>
<span class="p">}</span>
<span class="cm">/* Create SSL_CTX. */</span>
<span class="k">static</span> <span class="n">SSL_CTX</span><span class="o">*</span> <span class="nf">create_ssl_ctx</span><span class="p">(</span><span class="kt">void</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">SSL_CTX</span> <span class="o">*</span><span class="n">ssl_ctx</span><span class="p">;</span>
<span class="n">ssl_ctx</span> <span class="o">=</span> <span class="n">SSL_CTX_new</span><span class="p">(</span><span class="n">SSLv23_client_method</span><span class="p">());</span>
<span class="k">if</span><span class="p">(</span><span class="o">!</span><span class="n">ssl_ctx</span><span class="p">)</span> <span class="p">{</span>
<span class="n">errx</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="s">&quot;Could not create SSL/TLS context: %s&quot;</span><span class="p">,</span>
<span class="n">ERR_error_string</span><span class="p">(</span><span class="n">ERR_get_error</span><span class="p">(),</span> <span class="nb">NULL</span><span class="p">));</span>
<span class="p">}</span>
<span class="n">SSL_CTX_set_options</span><span class="p">(</span><span class="n">ssl_ctx</span><span class="p">,</span>
<span class="n">SSL_OP_ALL</span> <span class="o">|</span> <span class="n">SSL_OP_NO_SSLv2</span> <span class="o">|</span> <span class="n">SSL_OP_NO_COMPRESSION</span> <span class="o">|</span>
<span class="n">SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION</span><span class="p">);</span>
<span class="n">SSL_CTX_set_next_proto_select_cb</span><span class="p">(</span><span class="n">ssl_ctx</span><span class="p">,</span> <span class="n">select_next_proto_cb</span><span class="p">,</span> <span class="nb">NULL</span><span class="p">);</span>
<span class="k">return</span> <span class="n">ssl_ctx</span><span class="p">;</span>
<span class="p">}</span>
<span class="cm">/* Create SSL object */</span>
<span class="k">static</span> <span class="n">SSL</span><span class="o">*</span> <span class="nf">create_ssl</span><span class="p">(</span><span class="n">SSL_CTX</span> <span class="o">*</span><span class="n">ssl_ctx</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">SSL</span> <span class="o">*</span><span class="n">ssl</span><span class="p">;</span>
<span class="n">ssl</span> <span class="o">=</span> <span class="n">SSL_new</span><span class="p">(</span><span class="n">ssl_ctx</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="o">!</span><span class="n">ssl</span><span class="p">)</span> <span class="p">{</span>
<span class="n">errx</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="s">&quot;Could not create SSL/TLS session object: %s&quot;</span><span class="p">,</span>
<span class="n">ERR_error_string</span><span class="p">(</span><span class="n">ERR_get_error</span><span class="p">(),</span> <span class="nb">NULL</span><span class="p">));</span>
<span class="p">}</span>
<span class="k">return</span> <span class="n">ssl</span><span class="p">;</span>
<span class="p">}</span>
<span class="k">static</span> <span class="kt">void</span> <span class="nf">initialize_nghttp2_session</span><span class="p">(</span><span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">nghttp2_session_callbacks</span> <span class="n">callbacks</span> <span class="o">=</span> <span class="p">{</span><span class="mi">0</span><span class="p">};</span>
<span class="n">callbacks</span><span class="p">.</span><span class="n">send_callback</span> <span class="o">=</span> <span class="n">send_callback</span><span class="p">;</span>
<span class="n">callbacks</span><span class="p">.</span><span class="n">before_frame_send_callback</span> <span class="o">=</span> <span class="n">before_frame_send_callback</span><span class="p">;</span>
<span class="n">callbacks</span><span class="p">.</span><span class="n">on_frame_recv_callback</span> <span class="o">=</span> <span class="n">on_frame_recv_callback</span><span class="p">;</span>
<span class="n">callbacks</span><span class="p">.</span><span class="n">on_data_chunk_recv_callback</span> <span class="o">=</span> <span class="n">on_data_chunk_recv_callback</span><span class="p">;</span>
<span class="n">callbacks</span><span class="p">.</span><span class="n">on_stream_close_callback</span> <span class="o">=</span> <span class="n">on_stream_close_callback</span><span class="p">;</span>
<span class="n">callbacks</span><span class="p">.</span><span class="n">on_header_callback</span> <span class="o">=</span> <span class="n">on_header_callback</span><span class="p">;</span>
<span class="n">callbacks</span><span class="p">.</span><span class="n">on_begin_headers_callback</span> <span class="o">=</span> <span class="n">on_begin_headers_callback</span><span class="p">;</span>
<span class="n">nghttp2_session_client_new</span><span class="p">(</span><span class="o">&amp;</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">session</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">callbacks</span><span class="p">,</span> <span class="n">session_data</span><span class="p">);</span>
<span class="p">}</span>
<span class="k">static</span> <span class="kt">void</span> <span class="nf">send_client_connection_header</span><span class="p">(</span><span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">nghttp2_settings_entry</span> <span class="n">iv</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span> <span class="o">=</span> <span class="p">{</span>
<span class="p">{</span> <span class="n">NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS</span><span class="p">,</span> <span class="mi">100</span> <span class="p">}</span>
<span class="p">};</span>
<span class="kt">int</span> <span class="n">rv</span><span class="p">;</span>
<span class="n">bufferevent_write</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">bev</span><span class="p">,</span>
<span class="n">NGHTTP2_CLIENT_CONNECTION_PREFACE</span><span class="p">,</span>
<span class="n">NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN</span><span class="p">);</span>
<span class="n">rv</span> <span class="o">=</span> <span class="n">nghttp2_submit_settings</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">session</span><span class="p">,</span> <span class="n">NGHTTP2_FLAG_NONE</span><span class="p">,</span>
<span class="n">iv</span><span class="p">,</span> <span class="n">ARRLEN</span><span class="p">(</span><span class="n">iv</span><span class="p">));</span>
<span class="k">if</span><span class="p">(</span><span class="n">rv</span> <span class="o">!=</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">errx</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="s">&quot;Could not submit SETTINGS: %s&quot;</span><span class="p">,</span> <span class="n">nghttp2_strerror</span><span class="p">(</span><span class="n">rv</span><span class="p">));</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="cp">#define MAKE_NV(NAME, VALUE, VALUELEN) \</span>
<span class="cp"> { (uint8_t*)NAME, (uint8_t*)VALUE, sizeof(NAME) - 1, VALUELEN, \</span>
<span class="cp"> NGHTTP2_NV_FLAG_NONE }</span>
<span class="cp">#define MAKE_NV2(NAME, VALUE) \</span>
<span class="cp"> { (uint8_t*)NAME, (uint8_t*)VALUE, sizeof(NAME) - 1, sizeof(VALUE) - 1, \</span>
<span class="cp"> NGHTTP2_NV_FLAG_NONE }</span>
<span class="cm">/* Send HTTP request to the remote peer */</span>
<span class="k">static</span> <span class="kt">void</span> <span class="nf">submit_request</span><span class="p">(</span><span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="kt">int</span> <span class="n">rv</span><span class="p">;</span>
<span class="n">http2_stream_data</span> <span class="o">*</span><span class="n">stream_data</span> <span class="o">=</span> <span class="n">session_data</span><span class="o">-&gt;</span><span class="n">stream_data</span><span class="p">;</span>
<span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">uri</span> <span class="o">=</span> <span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">uri</span><span class="p">;</span>
<span class="k">const</span> <span class="k">struct</span> <span class="n">http_parser_url</span> <span class="o">*</span><span class="n">u</span> <span class="o">=</span> <span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">u</span><span class="p">;</span>
<span class="n">nghttp2_nv</span> <span class="n">hdrs</span><span class="p">[]</span> <span class="o">=</span> <span class="p">{</span>
<span class="n">MAKE_NV2</span><span class="p">(</span><span class="s">&quot;:method&quot;</span><span class="p">,</span> <span class="s">&quot;GET&quot;</span><span class="p">),</span>
<span class="n">MAKE_NV</span><span class="p">(</span><span class="s">&quot;:scheme&quot;</span><span class="p">,</span>
<span class="o">&amp;</span><span class="n">uri</span><span class="p">[</span><span class="n">u</span><span class="o">-&gt;</span><span class="n">field_data</span><span class="p">[</span><span class="n">UF_SCHEMA</span><span class="p">].</span><span class="n">off</span><span class="p">],</span> <span class="n">u</span><span class="o">-&gt;</span><span class="n">field_data</span><span class="p">[</span><span class="n">UF_SCHEMA</span><span class="p">].</span><span class="n">len</span><span class="p">),</span>
<span class="n">MAKE_NV</span><span class="p">(</span><span class="s">&quot;:authority&quot;</span><span class="p">,</span> <span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">authority</span><span class="p">,</span> <span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">authoritylen</span><span class="p">),</span>
<span class="n">MAKE_NV</span><span class="p">(</span><span class="s">&quot;:path&quot;</span><span class="p">,</span> <span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">path</span><span class="p">,</span> <span class="n">stream_data</span><span class="o">-&gt;</span><span class="n">pathlen</span><span class="p">)</span>
<span class="p">};</span>
<span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="s">&quot;Request headers:</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">);</span>
<span class="n">print_headers</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="n">hdrs</span><span class="p">,</span> <span class="n">ARRLEN</span><span class="p">(</span><span class="n">hdrs</span><span class="p">));</span>
<span class="n">rv</span> <span class="o">=</span> <span class="n">nghttp2_submit_request</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">session</span><span class="p">,</span> <span class="nb">NULL</span><span class="p">,</span>
<span class="n">hdrs</span><span class="p">,</span> <span class="n">ARRLEN</span><span class="p">(</span><span class="n">hdrs</span><span class="p">),</span> <span class="nb">NULL</span><span class="p">,</span> <span class="n">stream_data</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">rv</span> <span class="o">!=</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">errx</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="s">&quot;Could not submit HTTP request: %s&quot;</span><span class="p">,</span> <span class="n">nghttp2_strerror</span><span class="p">(</span><span class="n">rv</span><span class="p">));</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="cm">/* Serialize the frame and send (or buffer) the data to</span>
<span class="cm"> bufferevent. */</span>
<span class="k">static</span> <span class="kt">int</span> <span class="nf">session_send</span><span class="p">(</span><span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="kt">int</span> <span class="n">rv</span><span class="p">;</span>
<span class="n">rv</span> <span class="o">=</span> <span class="n">nghttp2_session_send</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">session</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">rv</span> <span class="o">!=</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">warnx</span><span class="p">(</span><span class="s">&quot;Fatal error: %s&quot;</span><span class="p">,</span> <span class="n">nghttp2_strerror</span><span class="p">(</span><span class="n">rv</span><span class="p">));</span>
<span class="k">return</span> <span class="o">-</span><span class="mi">1</span><span class="p">;</span>
<span class="p">}</span>
<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>
<span class="cm">/* readcb for bufferevent. Here we get the data from the input buffer</span>
<span class="cm"> of bufferevent and feed them to nghttp2 library. This may invoke</span>
<span class="cm"> nghttp2 callbacks. It may also queues the frame in nghttp2 session</span>
<span class="cm"> context. To send them, we call session_send() in the end. */</span>
<span class="k">static</span> <span class="kt">void</span> <span class="nf">readcb</span><span class="p">(</span><span class="k">struct</span> <span class="n">bufferevent</span> <span class="o">*</span><span class="n">bev</span><span class="p">,</span> <span class="kt">void</span> <span class="o">*</span><span class="n">ptr</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">ptr</span><span class="p">;</span>
<span class="kt">int</span> <span class="n">rv</span><span class="p">;</span>
<span class="k">struct</span> <span class="n">evbuffer</span> <span class="o">*</span><span class="n">input</span> <span class="o">=</span> <span class="n">bufferevent_get_input</span><span class="p">(</span><span class="n">bev</span><span class="p">);</span>
<span class="kt">size_t</span> <span class="n">datalen</span> <span class="o">=</span> <span class="n">evbuffer_get_length</span><span class="p">(</span><span class="n">input</span><span class="p">);</span>
<span class="kt">unsigned</span> <span class="kt">char</span> <span class="o">*</span><span class="n">data</span> <span class="o">=</span> <span class="n">evbuffer_pullup</span><span class="p">(</span><span class="n">input</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">);</span>
<span class="n">rv</span> <span class="o">=</span> <span class="n">nghttp2_session_mem_recv</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">session</span><span class="p">,</span> <span class="n">data</span><span class="p">,</span> <span class="n">datalen</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">rv</span> <span class="o">&lt;</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">warnx</span><span class="p">(</span><span class="s">&quot;Fatal error: %s&quot;</span><span class="p">,</span> <span class="n">nghttp2_strerror</span><span class="p">(</span><span class="n">rv</span><span class="p">));</span>
<span class="n">delete_http2_session_data</span><span class="p">(</span><span class="n">session_data</span><span class="p">);</span>
<span class="k">return</span><span class="p">;</span>
<span class="p">}</span>
<span class="n">evbuffer_drain</span><span class="p">(</span><span class="n">input</span><span class="p">,</span> <span class="n">rv</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">session_send</span><span class="p">(</span><span class="n">session_data</span><span class="p">)</span> <span class="o">!=</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">delete_http2_session_data</span><span class="p">(</span><span class="n">session_data</span><span class="p">);</span>
<span class="k">return</span><span class="p">;</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="cm">/* writecb for bufferevent. To greaceful shutdown after sending or</span>
<span class="cm"> receiving GOAWAY, we check the some conditions on the nghttp2</span>
<span class="cm"> library and output buffer of bufferevent. If it indicates we have</span>
<span class="cm"> no business to this session, tear down the connection. */</span>
<span class="k">static</span> <span class="kt">void</span> <span class="nf">writecb</span><span class="p">(</span><span class="k">struct</span> <span class="n">bufferevent</span> <span class="o">*</span><span class="n">bev</span><span class="p">,</span> <span class="kt">void</span> <span class="o">*</span><span class="n">ptr</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">ptr</span><span class="p">;</span>
<span class="k">if</span><span class="p">(</span><span class="n">nghttp2_session_want_read</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">session</span><span class="p">)</span> <span class="o">==</span> <span class="mi">0</span> <span class="o">&amp;&amp;</span>
<span class="n">nghttp2_session_want_write</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">session</span><span class="p">)</span> <span class="o">==</span> <span class="mi">0</span> <span class="o">&amp;&amp;</span>
<span class="n">evbuffer_get_length</span><span class="p">(</span><span class="n">bufferevent_get_output</span><span class="p">(</span><span class="n">session_data</span><span class="o">-&gt;</span><span class="n">bev</span><span class="p">))</span> <span class="o">==</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">delete_http2_session_data</span><span class="p">(</span><span class="n">session_data</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="cm">/* eventcb for bufferevent. For the purpose of simplicity and</span>
<span class="cm"> readability of the example program, we omitted the certificate and</span>
<span class="cm"> peer verification. After SSL/TLS handshake is over, initialize</span>
<span class="cm"> nghttp2 library session, and send client connection header. Then</span>
<span class="cm"> send HTTP request. */</span>
<span class="k">static</span> <span class="kt">void</span> <span class="nf">eventcb</span><span class="p">(</span><span class="k">struct</span> <span class="n">bufferevent</span> <span class="o">*</span><span class="n">bev</span><span class="p">,</span> <span class="kt">short</span> <span class="n">events</span><span class="p">,</span> <span class="kt">void</span> <span class="o">*</span><span class="n">ptr</span><span class="p">)</span>
<span class="p">{</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span> <span class="o">=</span> <span class="p">(</span><span class="n">http2_session_data</span><span class="o">*</span><span class="p">)</span><span class="n">ptr</span><span class="p">;</span>
<span class="k">if</span><span class="p">(</span><span class="n">events</span> <span class="o">&amp;</span> <span class="n">BEV_EVENT_CONNECTED</span><span class="p">)</span> <span class="p">{</span>
<span class="kt">int</span> <span class="n">fd</span> <span class="o">=</span> <span class="n">bufferevent_getfd</span><span class="p">(</span><span class="n">bev</span><span class="p">);</span>
<span class="kt">int</span> <span class="n">val</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
<span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="s">&quot;Connected</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">);</span>
<span class="n">setsockopt</span><span class="p">(</span><span class="n">fd</span><span class="p">,</span> <span class="n">IPPROTO_TCP</span><span class="p">,</span> <span class="n">TCP_NODELAY</span><span class="p">,</span> <span class="p">(</span><span class="kt">char</span> <span class="o">*</span><span class="p">)</span><span class="o">&amp;</span><span class="n">val</span><span class="p">,</span> <span class="k">sizeof</span><span class="p">(</span><span class="n">val</span><span class="p">));</span>
<span class="n">initialize_nghttp2_session</span><span class="p">(</span><span class="n">session_data</span><span class="p">);</span>
<span class="n">send_client_connection_header</span><span class="p">(</span><span class="n">session_data</span><span class="p">);</span>
<span class="n">submit_request</span><span class="p">(</span><span class="n">session_data</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">session_send</span><span class="p">(</span><span class="n">session_data</span><span class="p">)</span> <span class="o">!=</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">delete_http2_session_data</span><span class="p">(</span><span class="n">session_data</span><span class="p">);</span>
<span class="p">}</span>
<span class="k">return</span><span class="p">;</span>
<span class="p">}</span>
<span class="k">if</span><span class="p">(</span><span class="n">events</span> <span class="o">&amp;</span> <span class="n">BEV_EVENT_EOF</span><span class="p">)</span> <span class="p">{</span>
<span class="n">warnx</span><span class="p">(</span><span class="s">&quot;Disconnected from the remote host&quot;</span><span class="p">);</span>
<span class="p">}</span> <span class="k">else</span> <span class="k">if</span><span class="p">(</span><span class="n">events</span> <span class="o">&amp;</span> <span class="n">BEV_EVENT_ERROR</span><span class="p">)</span> <span class="p">{</span>
<span class="n">warnx</span><span class="p">(</span><span class="s">&quot;Network error&quot;</span><span class="p">);</span>
<span class="p">}</span> <span class="k">else</span> <span class="k">if</span><span class="p">(</span><span class="n">events</span> <span class="o">&amp;</span> <span class="n">BEV_EVENT_TIMEOUT</span><span class="p">)</span> <span class="p">{</span>
<span class="n">warnx</span><span class="p">(</span><span class="s">&quot;Timeout&quot;</span><span class="p">);</span>
<span class="p">}</span>
<span class="n">delete_http2_session_data</span><span class="p">(</span><span class="n">session_data</span><span class="p">);</span>
<span class="p">}</span>
<span class="cm">/* Start connecting to the remote peer |host:port| */</span>
<span class="k">static</span> <span class="kt">void</span> <span class="nf">initiate_connection</span><span class="p">(</span><span class="k">struct</span> <span class="n">event_base</span> <span class="o">*</span><span class="n">evbase</span><span class="p">,</span>
<span class="n">SSL_CTX</span> <span class="o">*</span><span class="n">ssl_ctx</span><span class="p">,</span>
<span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">host</span><span class="p">,</span> <span class="kt">uint16_t</span> <span class="n">port</span><span class="p">,</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span><span class="p">)</span>
<span class="p">{</span>
<span class="kt">int</span> <span class="n">rv</span><span class="p">;</span>
<span class="k">struct</span> <span class="n">bufferevent</span> <span class="o">*</span><span class="n">bev</span><span class="p">;</span>
<span class="n">SSL</span> <span class="o">*</span><span class="n">ssl</span><span class="p">;</span>
<span class="n">ssl</span> <span class="o">=</span> <span class="n">create_ssl</span><span class="p">(</span><span class="n">ssl_ctx</span><span class="p">);</span>
<span class="n">bev</span> <span class="o">=</span> <span class="n">bufferevent_openssl_socket_new</span><span class="p">(</span><span class="n">evbase</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">,</span> <span class="n">ssl</span><span class="p">,</span>
<span class="n">BUFFEREVENT_SSL_CONNECTING</span><span class="p">,</span>
<span class="n">BEV_OPT_DEFER_CALLBACKS</span> <span class="o">|</span>
<span class="n">BEV_OPT_CLOSE_ON_FREE</span><span class="p">);</span>
<span class="n">bufferevent_setcb</span><span class="p">(</span><span class="n">bev</span><span class="p">,</span> <span class="n">readcb</span><span class="p">,</span> <span class="n">writecb</span><span class="p">,</span> <span class="n">eventcb</span><span class="p">,</span> <span class="n">session_data</span><span class="p">);</span>
<span class="n">rv</span> <span class="o">=</span> <span class="n">bufferevent_socket_connect_hostname</span><span class="p">(</span><span class="n">bev</span><span class="p">,</span> <span class="n">session_data</span><span class="o">-&gt;</span><span class="n">dnsbase</span><span class="p">,</span>
<span class="n">AF_UNSPEC</span><span class="p">,</span> <span class="n">host</span><span class="p">,</span> <span class="n">port</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">rv</span> <span class="o">!=</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">errx</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="s">&quot;Could not connect to the remote host %s&quot;</span><span class="p">,</span> <span class="n">host</span><span class="p">);</span>
<span class="p">}</span>
<span class="n">session_data</span><span class="o">-&gt;</span><span class="n">bev</span> <span class="o">=</span> <span class="n">bev</span><span class="p">;</span>
<span class="p">}</span>
<span class="cm">/* Get resource denoted by the |uri|. The debug and error messages are</span>
<span class="cm"> printed in stderr, while the response body is printed in stdout. */</span>
<span class="k">static</span> <span class="kt">void</span> <span class="nf">run</span><span class="p">(</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">uri</span><span class="p">)</span>
<span class="p">{</span>
<span class="k">struct</span> <span class="n">http_parser_url</span> <span class="n">u</span><span class="p">;</span>
<span class="kt">char</span> <span class="o">*</span><span class="n">host</span><span class="p">;</span>
<span class="kt">uint16_t</span> <span class="n">port</span><span class="p">;</span>
<span class="kt">int</span> <span class="n">rv</span><span class="p">;</span>
<span class="n">SSL_CTX</span> <span class="o">*</span><span class="n">ssl_ctx</span><span class="p">;</span>
<span class="k">struct</span> <span class="n">event_base</span> <span class="o">*</span><span class="n">evbase</span><span class="p">;</span>
<span class="n">http2_session_data</span> <span class="o">*</span><span class="n">session_data</span><span class="p">;</span>
<span class="cm">/* Parse the |uri| and stores its components in |u| */</span>
<span class="n">rv</span> <span class="o">=</span> <span class="n">http_parser_parse_url</span><span class="p">(</span><span class="n">uri</span><span class="p">,</span> <span class="n">strlen</span><span class="p">(</span><span class="n">uri</span><span class="p">),</span> <span class="mi">0</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">u</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="n">rv</span> <span class="o">!=</span> <span class="mi">0</span><span class="p">)</span> <span class="p">{</span>
<span class="n">errx</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="s">&quot;Could not parse URI %s&quot;</span><span class="p">,</span> <span class="n">uri</span><span class="p">);</span>
<span class="p">}</span>
<span class="n">host</span> <span class="o">=</span> <span class="n">strndup</span><span class="p">(</span><span class="o">&amp;</span><span class="n">uri</span><span class="p">[</span><span class="n">u</span><span class="p">.</span><span class="n">field_data</span><span class="p">[</span><span class="n">UF_HOST</span><span class="p">].</span><span class="n">off</span><span class="p">],</span> <span class="n">u</span><span class="p">.</span><span class="n">field_data</span><span class="p">[</span><span class="n">UF_HOST</span><span class="p">].</span><span class="n">len</span><span class="p">);</span>
<span class="k">if</span><span class="p">(</span><span class="o">!</span><span class="p">(</span><span class="n">u</span><span class="p">.</span><span class="n">field_set</span> <span class="o">&amp;</span> <span class="p">(</span><span class="mi">1</span> <span class="o">&lt;&lt;</span> <span class="n">UF_PORT</span><span class="p">)))</span> <span class="p">{</span>
<span class="n">port</span> <span class="o">=</span> <span class="mi">443</span><span class="p">;</span>
<span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
<span class="n">port</span> <span class="o">=</span> <span class="n">u</span><span class="p">.</span><span class="n">port</span><span class="p">;</span>
<span class="p">}</span>
<span class="n">ssl_ctx</span> <span class="o">=</span> <span class="n">create_ssl_ctx</span><span class="p">();</span>
<span class="n">evbase</span> <span class="o">=</span> <span class="n">event_base_new</span><span class="p">();</span>
<span class="n">session_data</span> <span class="o">=</span> <span class="n">create_http2_session_data</span><span class="p">(</span><span class="n">evbase</span><span class="p">);</span>
<span class="n">session_data</span><span class="o">-&gt;</span><span class="n">stream_data</span> <span class="o">=</span> <span class="n">create_http2_stream_data</span><span class="p">(</span><span class="n">uri</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">u</span><span class="p">);</span>
<span class="n">initiate_connection</span><span class="p">(</span><span class="n">evbase</span><span class="p">,</span> <span class="n">ssl_ctx</span><span class="p">,</span> <span class="n">host</span><span class="p">,</span> <span class="n">port</span><span class="p">,</span> <span class="n">session_data</span><span class="p">);</span>
<span class="n">free</span><span class="p">(</span><span class="n">host</span><span class="p">);</span>
<span class="n">host</span> <span class="o">=</span> <span class="nb">NULL</span><span class="p">;</span>
<span class="n">event_base_loop</span><span class="p">(</span><span class="n">evbase</span><span class="p">,</span> <span class="mi">0</span><span class="p">);</span>
<span class="n">event_base_free</span><span class="p">(</span><span class="n">evbase</span><span class="p">);</span>
<span class="n">SSL_CTX_free</span><span class="p">(</span><span class="n">ssl_ctx</span><span class="p">);</span>
<span class="p">}</span>
<span class="kt">int</span> <span class="nf">main</span><span class="p">(</span><span class="kt">int</span> <span class="n">argc</span><span class="p">,</span> <span class="kt">char</span> <span class="o">**</span><span class="n">argv</span><span class="p">)</span>
<span class="p">{</span>
<span class="k">struct</span> <span class="n">sigaction</span> <span class="n">act</span><span class="p">;</span>
<span class="k">if</span><span class="p">(</span><span class="n">argc</span> <span class="o">&lt;</span> <span class="mi">2</span><span class="p">)</span> <span class="p">{</span>
<span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="s">&quot;Usage: libevent-client HTTPS_URI</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">);</span>
<span class="n">exit</span><span class="p">(</span><span class="n">EXIT_FAILURE</span><span class="p">);</span>
<span class="p">}</span>
<span class="n">memset</span><span class="p">(</span><span class="o">&amp;</span><span class="n">act</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="k">sizeof</span><span class="p">(</span><span class="k">struct</span> <span class="n">sigaction</span><span class="p">));</span>
<span class="n">act</span><span class="p">.</span><span class="n">sa_handler</span> <span class="o">=</span> <span class="n">SIG_IGN</span><span class="p">;</span>
<span class="n">sigaction</span><span class="p">(</span><span class="n">SIGPIPE</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">act</span><span class="p">,</span> <span class="nb">NULL</span><span class="p">);</span>
<span class="n">SSL_load_error_strings</span><span class="p">();</span>
<span class="n">SSL_library_init</span><span class="p">();</span>
<span class="n">run</span><span class="p">(</span><span class="n">argv</span><span class="p">[</span><span class="mi">1</span><span class="p">]);</span>
<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>
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