Added support for RFC 7413 (TCP Fast Open) on nghttpx proxy listening connections.

Fixed code as per PR comments

gennghttpxfun.py

@@ -102,6 +102,7 @@ OPTIONS = [
     "response-phase-file",
     "accept-proxy-protocol",
     "conf",
+    "fastopen",
 ]
 
 LOGVARS = [

src/shrpx.cc

@@ -107,6 +107,19 @@ namespace shrpx {
 // path.
 #define ENV_UNIX_PATH "NGHTTP2_UNIX_PATH"
 
+#ifndef _KERNEL_FASTOPEN
+#define _KERNEL_FASTOPEN
+// conditional define for TCP_FASTOPEN mostly on ubuntu
+#ifndef TCP_FASTOPEN
+#define TCP_FASTOPEN   23
+#endif
+
+// conditional define for SOL_TCP mostly on ubuntu
+#ifndef SOL_TCP
+#define SOL_TCP 6
+#endif
+#endif
+
 struct SignalServer {
   SignalServer()
       : ipc_fd{{-1, -1}}, server_fd(-1), server_fd6(-1),
@@ -605,6 +618,14 @@ int create_tcp_server_socket(int family) {
       continue;
     }
 
+    if(get_config()->fastopen > 0) {
+      val = get_config()->fastopen;
+      if (setsockopt(fd, SOL_TCP, TCP_FASTOPEN, &val,
+                   static_cast<socklen_t>(sizeof(val))) == -1) {
+        LOG(WARN) << "Failed to set TCP_FASTOPEN option to listener socket";
+      }
+    }
+
     if (listen(fd, get_config()->backlog) == -1) {
       auto error = errno;
       LOG(WARN) << "listen() syscall failed, error=" << error;
@@ -1009,6 +1030,7 @@ void fill_default_config() {
   mod_config()->tls_ticket_key_memcached_max_retry = 3;
   mod_config()->tls_ticket_key_memcached_max_fail = 2;
   mod_config()->tls_ticket_key_memcached_interval = 10_min;
+  mod_config()->fastopen = 0;
 }
 } // namespace
 
@@ -1217,7 +1239,14 @@ Performance:
               Default: )"
       << util::utos_with_unit(get_config()->downstream_response_buffer_size)
       << R"(
-
+  --fastopen=<N>
+              enables “TCP Fast Open” for the listening socket 
+              and limits the maximum length for the queue of connections 
+              that have not yet completed the three-way handshake.
+              If value is 0 then fast open is disabled.
+              Default: )"
+      << util::utos_with_unit(get_config()->fastopen)
+      << R"(
 Timeout:
   --frontend-http2-read-timeout=<DURATION>
               Specify  read  timeout  for  HTTP/2  and  SPDY  frontend
@@ -1775,6 +1804,7 @@ int main(int argc, char **argv) {
         {SHRPX_OPT_REQUEST_PHASE_FILE, required_argument, &flag, 91},
         {SHRPX_OPT_RESPONSE_PHASE_FILE, required_argument, &flag, 92},
         {SHRPX_OPT_ACCEPT_PROXY_PROTOCOL, no_argument, &flag, 93},
+        {SHRPX_OPT_FASTOPEN, required_argument, &flag, 94},
         {nullptr, 0, nullptr, 0}};
 
     int option_index = 0;
@@ -2180,6 +2210,10 @@ int main(int argc, char **argv) {
         // --accept-proxy-protocol
         cmdcfgs.emplace_back(SHRPX_OPT_ACCEPT_PROXY_PROTOCOL, "yes");
         break;
+      case 94:
+        // --fastopen
+        cmdcfgs.emplace_back(SHRPX_OPT_FASTOPEN, optarg);
+        break;
       default:
         break;
       }

src/shrpx_config.cc

@@ -649,6 +649,7 @@ enum {
   SHRPX_OPTID_DH_PARAM_FILE,
   SHRPX_OPTID_ERRORLOG_FILE,
   SHRPX_OPTID_ERRORLOG_SYSLOG,
+  SHRPX_OPTID_FASTOPEN,
   SHRPX_OPTID_FETCH_OCSP_RESPONSE_FILE,
   SHRPX_OPTID_FRONTEND,
   SHRPX_OPTID_FRONTEND_FRAME_DEBUG,
@@ -814,6 +815,11 @@ int option_lookup_token(const char *name, size_t namelen) {
         return SHRPX_OPTID_PID_FILE;
       }
       break;
+    case 'n':
+      if (util::strieq_l("fastope", name, 7)) {
+        return SHRPX_OPTID_FASTOPEN;
+      }
+      break;
     case 't':
       if (util::strieq_l("npn-lis", name, 7)) {
         return SHRPX_OPTID_NPN_LIST;
@@ -1444,6 +1450,21 @@ int parse_config(const char *opt, const char *optarg,
     mod_config()->errorlog_syslog = util::strieq(optarg, "yes");
 
     return 0;
+  case SHRPX_OPTID_FASTOPEN: {
+    int n;
+    if (parse_int(&n, opt, optarg) != 0) {
+      return -1;
+    }
+
+    if (n < 0) {
+      LOG(ERROR) << opt << ": " << optarg << " is not allowed";
+      return -1;
+    }
+
+    mod_config()->fastopen = n;
+
+    return 0;
+  }  
   case SHRPX_OPTID_BACKEND_KEEP_ALIVE_TIMEOUT:
     return parse_duration(&mod_config()->downstream_idle_read_timeout, opt,
                           optarg);

src/shrpx_config.h

@@ -187,6 +187,7 @@ constexpr char SHRPX_OPT_TLS_TICKET_KEY_MEMCACHED_MAX_FAIL[] =
 constexpr char SHRPX_OPT_REQUEST_PHASE_FILE[] = "request-phase-file";
 constexpr char SHRPX_OPT_RESPONSE_PHASE_FILE[] = "response-phase-file";
 constexpr char SHRPX_OPT_ACCEPT_PROXY_PROTOCOL[] = "accept-proxy-protocol";
+constexpr char SHRPX_OPT_FASTOPEN[] = "fastopen";
 
 union sockaddr_union {
   sockaddr_storage storage;
@@ -377,6 +378,7 @@ struct Config {
   int syslog_facility;
   int backlog;
   int argc;
+  int fastopen;
   uid_t uid;
   gid_t gid;
   pid_t pid;