nghttpx: Add --no-server-rewrite option not to rewrite server header field

gennghttpxfun.py

@@ -135,6 +135,7 @@ OPTIONS = [
     "api-max-request-body",
     "backend-max-backoff",
     "server-name",
+    "no-server-rewrite",
 ]
 
 LOGVARS = [

src/shrpx.cc

@@ -2208,6 +2208,10 @@ HTTP:
   --server-name=<NAME>
               Change server response header field value to <NAME>.
               Default: )" << get_config()->http.server_name << R"(
+  --no-server-rewrite
+              Don't rewrite server header field in default mode.  When
+              --http2-proxy is used, these headers will not be altered
+              regardless of this option.
 
 API:
   --api-max-request-body=<SIZE>
@@ -2837,6 +2841,7 @@ int main(int argc, char **argv) {
         {SHRPX_OPT_API_MAX_REQUEST_BODY.c_str(), required_argument, &flag, 126},
         {SHRPX_OPT_BACKEND_MAX_BACKOFF.c_str(), required_argument, &flag, 127},
         {SHRPX_OPT_SERVER_NAME.c_str(), required_argument, &flag, 128},
+        {SHRPX_OPT_NO_SERVER_REWRITE.c_str(), no_argument, &flag, 129},
         {nullptr, 0, nullptr, 0}};
 
     int option_index = 0;
@@ -3438,6 +3443,11 @@ int main(int argc, char **argv) {
         // --server-name
         cmdcfgs.emplace_back(SHRPX_OPT_SERVER_NAME, StringRef{optarg});
         break;
+      case 129:
+        // --no-server-rewrite
+        cmdcfgs.emplace_back(SHRPX_OPT_NO_SERVER_REWRITE,
+                             StringRef::from_lit("yes"));
+        break;
       default:
         break;
       }

src/shrpx_config.cc

@@ -1288,6 +1288,9 @@ int option_lookup_token(const char *name, size_t namelen) {
   case 17:
     switch (name[16]) {
     case 'e':
+      if (util::strieq_l("no-server-rewrit", name, 16)) {
+        return SHRPX_OPTID_NO_SERVER_REWRITE;
+      }
       if (util::strieq_l("worker-write-rat", name, 16)) {
         return SHRPX_OPTID_WORKER_WRITE_RATE;
       }
@@ -2682,6 +2685,10 @@ int parse_config(Config *config, int optid, const StringRef &opt,
     config->http.server_name =
         ImmutableString{std::begin(optarg), std::end(optarg)};
 
+    return 0;
+  case SHRPX_OPTID_NO_SERVER_REWRITE:
+    config->http.no_server_rewrite = util::strieq_l("yes", optarg);
+
     return 0;
   case SHRPX_OPTID_CONF:
     LOG(WARN) << "conf: ignored";

src/shrpx_config.h

@@ -285,6 +285,8 @@ constexpr auto SHRPX_OPT_API_MAX_REQUEST_BODY =
 constexpr auto SHRPX_OPT_BACKEND_MAX_BACKOFF =
     StringRef::from_lit("backend-max-backoff");
 constexpr auto SHRPX_OPT_SERVER_NAME = StringRef::from_lit("server-name");
+constexpr auto SHRPX_OPT_NO_SERVER_REWRITE =
+    StringRef::from_lit("no-server-rewrite");
 
 constexpr size_t SHRPX_OBFUSCATED_NODE_LENGTH = 8;
 
@@ -561,6 +563,7 @@ struct HttpConfig {
   bool no_via;
   bool no_location_rewrite;
   bool no_host_rewrite;
+  bool no_server_rewrite;
 };
 
 struct Http2Config {
@@ -832,6 +835,7 @@ enum {
   SHRPX_OPTID_NO_LOCATION_REWRITE,
   SHRPX_OPTID_NO_OCSP,
   SHRPX_OPTID_NO_SERVER_PUSH,
+  SHRPX_OPTID_NO_SERVER_REWRITE,
   SHRPX_OPTID_NO_VIA,
   SHRPX_OPTID_NPN_LIST,
   SHRPX_OPTID_OCSP_UPDATE_INTERVAL,

src/shrpx_http2_upstream.cc

@@ -1537,7 +1537,7 @@ int Http2Upstream::on_downstream_header_complete(Downstream *downstream) {
 
   http2::copy_headers_to_nva_nocopy(nva, resp.fs.headers());
 
-  if (!get_config()->http2_proxy) {
+  if (!get_config()->http2_proxy && !httpconf.no_server_rewrite) {
     nva.push_back(
         http2::make_nv_ls_nocopy("server", StringRef{httpconf.server_name}));
   } else {

src/shrpx_https_upstream.cc

@@ -1078,7 +1078,7 @@ int HttpsUpstream::on_downstream_header_complete(Downstream *downstream) {
     }
   }
 
-  if (!get_config()->http2_proxy) {
+  if (!get_config()->http2_proxy && !httpconf.no_server_rewrite) {
     buf->append("Server: ");
     buf->append(httpconf.server_name);
     buf->append("\r\n");

src/shrpx_spdy_upstream.cc

@@ -1100,7 +1100,7 @@ int SpdyUpstream::on_downstream_header_complete(Downstream *downstream) {
     nv[hdidx++] = hd.value.c_str();
   }
 
-  if (!get_config()->http2_proxy) {
+  if (!get_config()->http2_proxy && !httpconf.no_server_rewrite) {
     nv[hdidx++] = "server";
     nv[hdidx++] = httpconf.server_name.c_str();
   } else {