nghttpx: Rewirte server header field if configured as reverse proxy

src/http2.cc

@@ -193,6 +193,7 @@ const char *IGN_HD[] = {
   "http2-settings",
   "keep-alive",
   "proxy-connection",
+  "server",
   "te",
   "transfer-encoding",
   "upgrade",
@@ -213,6 +214,7 @@ const char *HTTP1_IGN_HD[] = {
   "http2-settings",
   "keep-alive",
   "proxy-connection",
+  "server",
   "upgrade",
   "via",
   "x-forwarded-for",

src/shrpx_http2_upstream.cc

@@ -1183,8 +1183,8 @@ int Http2Upstream::on_downstream_header_complete(Downstream *downstream)
   auto end_headers = std::end(downstream->get_response_headers());
   size_t nheader = downstream->get_response_headers().size();
   auto nva = std::vector<nghttp2_nv>();
-  // 2 means :status and possible via header field.
-  nva.reserve(nheader + 2 + get_config()->add_response_headers.size());
+  // 3 means :status and possible server and via header field.
+  nva.reserve(nheader + 3 + get_config()->add_response_headers.size());
   std::string via_value;
   auto response_status = util::utos(downstream->get_response_http_status());
   nva.push_back(http2::make_nv_ls(":status", response_status));
@@ -1210,6 +1210,15 @@ int Http2Upstream::on_downstream_header_complete(Downstream *downstream)
     return 0;
   }
 
+  if(!get_config()->http2_proxy && !get_config()->client_proxy) {
+    nva.push_back(http2::make_nv_lc("server", get_config()->server_name));
+  } else {
+    auto server = downstream->get_norm_response_header("server");
+    if(server != end_headers) {
+      nva.push_back(http2::make_nv_ls("server", (*server).value));
+    }
+  }
+
   auto via = downstream->get_norm_response_header("via");
   if(get_config()->no_via) {
     if(via != end_headers) {

src/shrpx_https_upstream.cc

@@ -823,6 +823,19 @@ int HttpsUpstream::on_downstream_header_complete(Downstream *downstream)
     }
   }
 
+  if(!get_config()->http2_proxy && !get_config()->client_proxy) {
+    hdrs += "Server: ";
+    hdrs += get_config()->server_name;
+    hdrs += "\r\n";
+  } else {
+    auto server = downstream->get_norm_response_header("server");
+    if(server != end_headers) {
+      hdrs += "Server: ";
+      hdrs += (*server).value;
+      hdrs += "\r\n";
+    }
+  }
+
   auto via = downstream->get_norm_response_header("via");
   if(get_config()->no_via) {
     if(via != end_headers) {

src/shrpx_spdy_upstream.cc

@@ -917,9 +917,9 @@ int SpdyUpstream::on_downstream_header_complete(Downstream *downstream)
       (get_client_handler()->get_upstream_scheme(), get_config()->port);
   }
   size_t nheader = downstream->get_response_headers().size();
-  // 6 means :status, :version and possible via header field.
+  // 8 means server, :status, :version and possible via header field.
   auto nv = util::make_unique<const char*[]>
-    (nheader * 2 + 6 + get_config()->add_response_headers.size() * 2 + 1);
+    (nheader * 2 + 8 + get_config()->add_response_headers.size() * 2 + 1);
 
   size_t hdidx = 0;
   std::string via_value;
@@ -939,11 +939,20 @@ int SpdyUpstream::on_downstream_header_complete(Downstream *downstream)
     } else if(!get_config()->no_via &&
               util::strieq(hd.name.c_str(), "via")) {
       via_value = hd.value;
+    } else if(!get_config()->http2_proxy && !get_config()->client_proxy &&
+              util::strieq(hd.name.c_str(), "server")) {
+      // Rewrite server header field later
     } else {
       nv[hdidx++] = hd.name.c_str();
       nv[hdidx++] = hd.value.c_str();
     }
   }
+
+  if(!get_config()->http2_proxy && !get_config()->client_proxy) {
+    nv[hdidx++] = "server";
+    nv[hdidx++] = get_config()->server_name;
+  }
+
   if(!get_config()->no_via) {
     if(!via_value.empty()) {
       via_value += ", ";