Added --add-x-forwarded-for option.

This option append X-Forwarded-For header field to the downstream
request.

examples/shrpx.cc

@@ -344,6 +344,9 @@ void print_help(std::ostream& out)
       << "    -D, --daemon       Run in a background. If -D is used, the\n"
       << "                       current working directory is changed to '/'.\n"
       << "    -s, --spdy-proxy   SSL/SPDY proxy mode.\n"
+      << "    --add-x-forwarded-for\n"
+      << "                       Append X-Forwarded-For header field to the\n"
+      << "                       downstream request.\n"
       << "    -h, --help         Print this help.\n"
       << std::endl;
 }
@@ -361,6 +364,7 @@ int main(int argc, char **argv)
   uint16_t backend_port;
 
   while(1) {
+    int flag;
     static option long_options[] = {
       {"backend", required_argument, 0, 'b' },
       {"frontend", required_argument, 0, 'f' },
@@ -369,6 +373,7 @@ int main(int argc, char **argv)
       {"log-level", required_argument, 0, 'L' },
       {"daemon", no_argument, 0, 'D' },
       {"spdy-proxy", no_argument, 0, 's' },
+      {"add-x-forwarded-for", no_argument, &flag, 1},
       {"help", no_argument, 0, 'h' },
       {0, 0, 0, 0 }
     };
@@ -420,6 +425,16 @@ int main(int argc, char **argv)
       break;
     case '?':
       exit(EXIT_FAILURE);
+    case 0:
+      switch(flag) {
+      case 1:
+        // --add-x-forwarded-for
+        mod_config()->add_x_forwarded_for = true;
+        break;
+      default:
+        break;
+      }
+      break;
     default:
       break;
     }

examples/shrpx_config.cc

@@ -41,7 +41,8 @@ Config::Config()
     downstream_addrlen(0),
     num_worker(0),
     spdy_max_concurrent_streams(0),
-    spdy_proxy(false)
+    spdy_proxy(false),
+    add_x_forwarded_for(false)
 {}
 
 namespace {

examples/shrpx_config.h

@@ -68,6 +68,7 @@ struct Config {
   size_t num_worker;
   size_t spdy_max_concurrent_streams;
   bool spdy_proxy;
+  bool add_x_forwarded_for;
   Config();
 };
 

examples/shrpx_downstream.cc

@@ -296,13 +296,13 @@ bool Downstream::get_output_buffer_full()
 // Downstream. Otherwise, the program will crash.
 int Downstream::push_request_headers()
 {
-  bool xff_found = false;
   std::string hdrs = request_method_;
   hdrs += " ";
   hdrs += request_path_;
   hdrs += " ";
   hdrs += "HTTP/1.1\r\n";
   std::string via_value;
+  std::string xff_value;
   for(Headers::const_iterator i = request_headers_.begin();
       i != request_headers_.end(); ++i) {
     if(util::strieq((*i).first.c_str(), "X-Forwarded-Proto") ||
@@ -315,6 +315,10 @@ int Downstream::push_request_headers()
       via_value = (*i).second;
       continue;
     }
+    if(util::strieq((*i).first.c_str(), "x-forwarded-for")) {
+      xff_value = (*i).second;
+      continue;
+    }
     if(util::strieq((*i).first.c_str(), "expect") &&
        util::strifind((*i).second.c_str(), "100-continue")) {
       continue;
@@ -322,22 +326,25 @@ int Downstream::push_request_headers()
     hdrs += (*i).first;
     hdrs += ": ";
     hdrs += (*i).second;
-    if(!xff_found && util::strieq((*i).first.c_str(), "X-Forwarded-For")) {
-      xff_found = true;
-      hdrs += ", ";
-      hdrs += upstream_->get_client_handler()->get_ipaddr();
-    }
     hdrs += "\r\n";
   }
   if(request_connection_close_) {
     hdrs += "Connection: close\r\n";
   }
-  if(request_method_ != "CONNECT") {
+  if(get_config()->add_x_forwarded_for) {
-    if(!xff_found) {
     hdrs += "X-Forwarded-For: ";
+    if(!xff_value.empty()) {
+      hdrs += xff_value;
+      hdrs += ", ";
+    }
     hdrs += upstream_->get_client_handler()->get_ipaddr();
     hdrs += "\r\n";
+  } else if(!xff_value.empty()) {
+    hdrs += "X-Forwarded-For: ";
+    hdrs += xff_value;
+    hdrs += "\r\n";
   }
+  if(request_method_ != "CONNECT") {
     hdrs += "X-Forwarded-Proto: ";
     if(util::istartsWith(request_path_, "http:")) {
       hdrs += "http";