Add nghttp2_on_begin_frame_callback

nghttp2_on_begin_frame_callback will be invoked when a frame header is
received.

lib/includes/nghttp2/nghttp2.h

@@ -1163,6 +1163,9 @@ typedef ssize_t (*nghttp2_recv_callback)
  * If ``frame->hd.flags & NGHTTP2_FLAG_END_STREAM`` is nonzero, the
  * |frame| is the last frame from the remote peer in this stream.
  *
+ * This callback won't be called for CONTINUATION frames.
+ * HEADERS/PUSH_PROMISE + CONTINUATIONs are treated as single frame.
+ *
  * The implementation of this function must return 0 if it succeeds.
  * If nonzero value is returned, it is treated as fatal error and
  * `nghttp2_session_recv()` and `nghttp2_session_mem_recv()` functions
@@ -1440,6 +1443,31 @@ typedef ssize_t (*nghttp2_select_padding_callback)
  size_t max_payloadlen,
  void *user_data);
 
+/**
+ * @functypedef
+ *
+ * Callback function invoked when a frame header is received.  The
+ * |hd| points to received frame header.
+ *
+ * Unlike :type:`nghttp2_on_frame_recv_callback`, this callback will
+ * also be called when frame header of CONTINUATION frame is received.
+ *
+ * If both :type:`nghttp2_on_begin_frame_callback` and
+ * :type:`nghttp2_on_begin_headers_callback` are set and HEADERS or
+ * PUSH_PROMISE is received, :type:`nghttp2_on_begin_frame_callback`
+ * will be called first.
+ *
+ * The implementation of this function must return 0 if it succeeds.
+ * If nonzero value is returned, it is treated as fatal error and
+ * `nghttp2_session_recv()` and `nghttp2_session_mem_recv()` functions
+ * immediately return :enum:`NGHTTP2_ERR_CALLBACK_FAILURE`.
+ *
+ * To set this callback to :type:`nghttp2_session_callbacks`, use
+ * `nghttp2_session_callbacks_set_on_begin_frame_callback()`.
+ */
+typedef int (*nghttp2_on_begin_frame_callback)
+(nghttp2_session *session, const nghttp2_frame_hd *hd, void *user_data);
+
 struct nghttp2_session_callbacks;
 
 /**
@@ -1608,6 +1636,15 @@ void nghttp2_session_callbacks_set_data_source_read_length_callback
 (nghttp2_session_callbacks *cbs,
  nghttp2_data_source_read_length_callback data_source_read_length_callback);
 
+/**
+ * @function
+ *
+ * Sets callback function invoked when a frame header is received.
+ */
+void nghttp2_session_callbacks_set_on_begin_frame_callback
+(nghttp2_session_callbacks *cbs,
+ nghttp2_on_begin_frame_callback on_begin_frame_callback);
+
 struct nghttp2_option;
 
 /**
@@ -1879,7 +1916,10 @@ ssize_t nghttp2_session_mem_send(nghttp2_session *session,
  * 1. :type:`nghttp2_recv_callback` is invoked one or more times to
  *    receive frame header.
  *
- * 2. If the frame is DATA frame:
+ * 2. When frame header is received,
+ *    :type:`nghttp2_on_begin_frame_callback` is invoked.
+ *
+ * 3. If the frame is DATA frame:
  *
  *    1. :type:`nghttp2_recv_callback` is invoked to receive DATA
  *       payload. For each chunk of data,
@@ -1890,7 +1930,7 @@ ssize_t nghttp2_session_mem_send(nghttp2_session *session,
  *       reception of the frame triggers the closure of the stream,
  *       :type:`nghttp2_on_stream_close_callback` is invoked.
  *
- * 3. If the frame is the control frame:
+ * 4. If the frame is the control frame:
  *
  *    1. :type:`nghttp2_recv_callback` is invoked one or more times to
  *       receive whole frame.

lib/nghttp2_callbacks.c

@@ -130,3 +130,10 @@ void nghttp2_session_callbacks_set_data_source_read_length_callback
 {
   cbs->read_length_callback = data_source_read_length_callback;
 }
+
+void nghttp2_session_callbacks_set_on_begin_frame_callback
+(nghttp2_session_callbacks *cbs,
+ nghttp2_on_begin_frame_callback on_begin_frame_callback)
+{
+  cbs->on_begin_frame_callback = on_begin_frame_callback;
+}

lib/nghttp2_callbacks.h

@@ -102,6 +102,10 @@ struct nghttp2_session_callbacks {
    * `nghttp2_data_source_read_callback()`
    */
   nghttp2_data_source_read_length_callback read_length_callback;
+  /**
+   * Sets callback function invoked when a frame header is received.
+   */
+  nghttp2_on_begin_frame_callback on_begin_frame_callback;
 };
 
 #endif /* NGHTTP2_CALLBACKS_H */

lib/nghttp2_session.c

@@ -2453,6 +2453,24 @@ static ssize_t session_recv(nghttp2_session *session, uint8_t *buf, size_t len)
   return rv;
 }
 
+static int session_call_on_begin_frame
+(nghttp2_session *session, const nghttp2_frame_hd *hd)
+{
+  int rv;
+
+  if(session->callbacks.on_begin_frame_callback) {
+
+    rv = session->callbacks.on_begin_frame_callback
+      (session, hd, session->user_data);
+
+    if(rv != 0) {
+      return NGHTTP2_ERR_CALLBACK_FAILURE;
+    }
+  }
+
+  return 0;
+}
+
 static int session_call_on_frame_received
 (nghttp2_session *session, nghttp2_frame *frame)
 {
@@ -4295,7 +4313,9 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session,
 
   for(;;) {
     switch(iframe->state) {
-    case NGHTTP2_IB_READ_HEAD:
+    case NGHTTP2_IB_READ_HEAD: {
+      int on_begin_frame_called = 0;
+
       DEBUGF(fprintf(stderr, "recv: [IB_READ_HEAD]\n"));
 
       readlen = inbound_frame_buf_read(iframe, in, last);
@@ -4424,6 +4444,17 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session,
           break;
         }
 
+        /* Call on_begin_frame_callback here because
+           session_process_headers_frame() may call
+           on_begin_headers_callback */
+        rv = session_call_on_begin_frame(session, &iframe->frame.hd);
+
+        if(nghttp2_is_fatal(rv)) {
+          return rv;
+        }
+
+        on_begin_frame_called = 1;
+
         rv = session_process_headers_frame(session);
         if(nghttp2_is_fatal(rv)) {
           return rv;
@@ -4632,7 +4663,25 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session,
 
         break;
       }
+
+      if(!on_begin_frame_called) {
+        switch(iframe->state) {
+        case NGHTTP2_IB_IGN_HEADER_BLOCK:
+        case NGHTTP2_IB_IGN_PAYLOAD:
+        case NGHTTP2_IB_FRAME_SIZE_ERROR:
+        case NGHTTP2_IB_IGN_DATA:
+          break;
+        default:
+          rv = session_call_on_begin_frame(session, &iframe->frame.hd);
+
+          if(nghttp2_is_fatal(rv)) {
+            return rv;
+          }
+        }
+      }
+
       break;
+    }
     case NGHTTP2_IB_READ_NBYTE:
       DEBUGF(fprintf(stderr, "recv: [IB_READ_NBYTE]\n"));
 
@@ -5105,6 +5154,12 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session,
 
       if(iframe->state == NGHTTP2_IB_EXPECT_CONTINUATION) {
         iframe->state = NGHTTP2_IB_READ_HEADER_BLOCK;
+
+        rv = session_call_on_begin_frame(session, &cont_hd);
+
+        if(nghttp2_is_fatal(rv)) {
+          return rv;
+        }
       } else {
         iframe->state = NGHTTP2_IB_IGN_HEADER_BLOCK;
       }

tests/nghttp2_session_test.c

@@ -75,6 +75,7 @@ typedef struct {
   nghttp2_nv nv;
   size_t data_chunk_len;
   size_t padlen;
+  int begin_frame_cb_called;
 } my_user_data;
 
 static void scripted_data_feed_init2(scripted_data_feed *df,
@@ -156,6 +157,15 @@ static ssize_t accumulator_send_callback(nghttp2_session *session,
   return len;
 }
 
+static int on_begin_frame_callback(nghttp2_session *session,
+                                   const nghttp2_frame_hd *hd,
+                                   void *user_data)
+{
+  my_user_data *ud = (my_user_data*)user_data;
+  ++ud->begin_frame_cb_called;
+  return 0;
+}
+
 static int on_frame_recv_callback(nghttp2_session *session,
                                   const nghttp2_frame *frame,
                                   void *user_data)
@@ -409,6 +419,7 @@ void test_nghttp2_session_recv(void)
   callbacks.send_callback = null_send_callback;
   callbacks.recv_callback = scripted_recv_callback;
   callbacks.on_frame_recv_callback = on_frame_recv_callback;
+  callbacks.on_begin_frame_callback = on_begin_frame_callback;
 
   user_data.df = &df;
 
@@ -435,10 +446,13 @@ void test_nghttp2_session_recv(void)
   nghttp2_frame_headers_free(&frame.headers);
 
   user_data.frame_recv_cb_called = 0;
+  user_data.begin_frame_cb_called = 0;
+
   while((ssize_t)df.seqidx < framelen) {
     CU_ASSERT(0 == nghttp2_session_recv(session));
   }
   CU_ASSERT(1 == user_data.frame_recv_cb_called);
+  CU_ASSERT(1 == user_data.begin_frame_cb_called);
 
   nghttp2_bufs_reset(&bufs);
 
@@ -453,9 +467,33 @@ void test_nghttp2_session_recv(void)
 
   scripted_data_feed_init2(&df, &bufs);
   user_data.frame_recv_cb_called = 0;
+  user_data.begin_frame_cb_called = 0;
 
   CU_ASSERT(0 == nghttp2_session_recv(session));
   CU_ASSERT(1 == user_data.frame_recv_cb_called);
+  CU_ASSERT(1 == user_data.begin_frame_cb_called);
+
+  nghttp2_bufs_reset(&bufs);
+
+  /* Receive PRIORITY */
+  nghttp2_frame_priority_init(&frame.priority, 5, &pri_spec_default);
+
+  rv = nghttp2_frame_pack_priority(&bufs, &frame.priority);
+
+  CU_ASSERT(0 == rv);
+
+  nghttp2_frame_priority_free(&frame.priority);
+
+  scripted_data_feed_init2(&df, &bufs);
+
+  user_data.frame_recv_cb_called = 0;
+  user_data.begin_frame_cb_called = 0;
+
+  CU_ASSERT(0 == nghttp2_session_recv(session));
+  CU_ASSERT(1 == user_data.frame_recv_cb_called);
+  CU_ASSERT(1 == user_data.begin_frame_cb_called);
+
+  nghttp2_bufs_reset(&bufs);
 
   nghttp2_hd_deflate_free(&deflater);
   nghttp2_session_del(session);
@@ -463,8 +501,6 @@ void test_nghttp2_session_recv(void)
   /* Some tests for frame too large */
   nghttp2_session_server_new(&session, &callbacks, &user_data);
 
-  nghttp2_bufs_reset(&bufs);
-
   /* Receive PING with too large payload */
   nghttp2_frame_ping_init(&frame.ping, NGHTTP2_FLAG_NONE, NULL);
 
@@ -485,8 +521,12 @@ void test_nghttp2_session_recv(void)
 
   scripted_data_feed_init2(&df, &bufs);
   user_data.frame_recv_cb_called = 0;
+  user_data.begin_frame_cb_called = 0;
+
   CU_ASSERT(0 == nghttp2_session_recv(session));
   CU_ASSERT(0 == user_data.frame_recv_cb_called);
+  CU_ASSERT(0 == user_data.begin_frame_cb_called);
+
   item = nghttp2_session_get_next_ob_item(session);
   CU_ASSERT(NGHTTP2_GOAWAY == OB_CTRL_TYPE(item));
   CU_ASSERT(NGHTTP2_FRAME_SIZE_ERROR == OB_CTRL(item)->goaway.error_code);
@@ -760,6 +800,7 @@ void test_nghttp2_session_recv_continuation(void)
   memset(&callbacks, 0, sizeof(nghttp2_session_callbacks));
   callbacks.on_header_callback = on_header_callback;
   callbacks.on_begin_headers_callback = on_begin_headers_callback;
+  callbacks.on_begin_frame_callback = on_begin_frame_callback;
 
   nghttp2_session_server_new(&session, &callbacks, &ud);
 
@@ -816,9 +857,12 @@ void test_nghttp2_session_recv_continuation(void)
   CU_ASSERT(0 == nghttp2_buf_len(buf));
 
   ud.header_cb_called = 0;
+  ud.begin_frame_cb_called = 0;
+
   rv = nghttp2_session_mem_recv(session, data, datalen);
   CU_ASSERT((ssize_t)datalen == rv);
   CU_ASSERT(2 == ud.header_cb_called);
+  CU_ASSERT(3 == ud.begin_frame_cb_called);
 
   nghttp2_hd_deflate_free(&deflater);
   nghttp2_session_del(session);