nghttpx: Add --add-request-header option

src/shrpx.cc

@@ -1350,6 +1350,12 @@ HTTP:
               HTTP/1.1  frontend.  This  option can  be used  multiple
               times   to   specify  multiple   alternative   services.
               Example: --altsvc=h2,443
+  --add-request-header=<HEADER>
+              Specify additional header field to add to request header
+              set.  This  option just  appends header field  and won't
+              replace anything  already set.  This option  can be used
+              several  times   to  specify  multiple   header  fields.
+              Example: --add-request-header="foo: bar"
   --add-response-header=<HEADER>
               Specify  additional  header  field to  add  to  response
               header set.   This option just appends  header field and
@@ -1544,6 +1550,7 @@ int main(int argc, char **argv) {
         {SHRPX_OPT_NO_OCSP, no_argument, &flag, 79},
         {SHRPX_OPT_HEADER_FIELD_BUFFER, required_argument, &flag, 80},
         {SHRPX_OPT_MAX_HEADER_FIELDS, required_argument, &flag, 81},
+        {SHRPX_OPT_ADD_REQUEST_HEADER, required_argument, &flag, 82},
         {nullptr, 0, nullptr, 0}};
 
     int option_index = 0;
@@ -1902,6 +1909,10 @@ int main(int argc, char **argv) {
         // --max-header-fields
         cmdcfgs.emplace_back(SHRPX_OPT_MAX_HEADER_FIELDS, optarg);
         break;
+      case 82:
+        // --add-request-header
+        cmdcfgs.emplace_back(SHRPX_OPT_ADD_REQUEST_HEADER, optarg);
+        break;
       default:
         break;
       }

src/shrpx_config.cc

@@ -997,14 +997,18 @@ int parse_config(const char *opt, const char *optarg) {
     return 0;
   }
 
-  if (util::strieq(opt, SHRPX_OPT_ADD_RESPONSE_HEADER)) {
+  if (util::strieq(opt, SHRPX_OPT_ADD_REQUEST_HEADER) ||
+      util::strieq(opt, SHRPX_OPT_ADD_RESPONSE_HEADER)) {
     auto p = parse_header(optarg);
     if (p.first.empty()) {
       LOG(ERROR) << opt << ": header field name is empty: " << optarg;
       return -1;
     }
-    mod_config()->add_response_headers.push_back(std::move(p));
-
+    if (util::strieq(opt, SHRPX_OPT_ADD_REQUEST_HEADER)) {
+      mod_config()->add_request_headers.push_back(std::move(p));
+    } else {
+      mod_config()->add_response_headers.push_back(std::move(p));
+    }
     return 0;
   }
 

src/shrpx_config.h

@@ -140,6 +140,7 @@ constexpr char SHRPX_OPT_HTTP2_NO_COOKIE_CRUMBLING[] =
 constexpr char SHRPX_OPT_FRONTEND_FRAME_DEBUG[] = "frontend-frame-debug";
 constexpr char SHRPX_OPT_PADDING[] = "padding";
 constexpr char SHRPX_OPT_ALTSVC[] = "altsvc";
+constexpr char SHRPX_OPT_ADD_REQUEST_HEADER[] = "add-request-header";
 constexpr char SHRPX_OPT_ADD_RESPONSE_HEADER[] = "add-response-header";
 constexpr char SHRPX_OPT_WORKER_FRONTEND_CONNECTIONS[] =
     "worker-frontend-connections";
@@ -220,6 +221,7 @@ struct Config {
   // The list of (private key file, certificate file) pair
   std::vector<std::pair<std::string, std::string>> subcerts;
   std::vector<AltSvc> altsvcs;
+  std::vector<std::pair<std::string, std::string>> add_request_headers;
   std::vector<std::pair<std::string, std::string>> add_response_headers;
   std::vector<unsigned char> alpn_prefs;
   std::vector<LogFragment> accesslog_format;

src/shrpx_http2_downstream_connection.cc

@@ -313,7 +313,8 @@ int Http2DownstreamConnection::push_request_headers() {
   // 7. x-forwarded-proto (optional)
   // 8. te (optional)
   auto nva = std::vector<nghttp2_nv>();
-  nva.reserve(nheader + 8 + cookies.size());
+  nva.reserve(nheader + 8 + cookies.size() +
+              get_config()->add_request_headers.size());
 
   std::string via_value;
   std::string xff_value;
@@ -411,6 +412,10 @@ int Http2DownstreamConnection::push_request_headers() {
     nva.push_back(http2::make_nv_ll("te", "trailers"));
   }
 
+  for (auto &p : get_config()->add_request_headers) {
+    nva.push_back(http2::make_nv(p.first, p.second));
+  }
+
   if (LOG_ENABLED(INFO)) {
     std::stringstream ss;
     for (auto &nv : nva) {

src/shrpx_http_downstream_connection.cc

@@ -366,6 +366,13 @@ int HttpDownstreamConnection::push_request_headers() {
     hdrs += "\r\n";
   }
 
+  for (auto &p : get_config()->add_request_headers) {
+    hdrs += p.first;
+    hdrs += ": ";
+    hdrs += p.second;
+    hdrs += "\r\n";
+  }
+
   hdrs += "\r\n";
   if (LOG_ENABLED(INFO)) {
     const char *hdrp;