nghttpx: Don't allow application protocol not listed in --npn-list option

src/shrpx.cc

@@ -602,7 +602,7 @@ void print_help(std::ostream& out)
       << "                       Path to file that contains DH parameters in\n"
       << "                       PEM format. Without this option, DHE cipher\n"
       << "                       suites are not available.\n"
-      << "    --npn-list=<LIST>  Comma delimited list of NPN protocol sorted\n"
+      << "    --npn-list=<LIST>  Comma delimited list of NPN/ALPN protocol sorted\n"
       << "                       in the order of preference. That means\n"
       << "                       most desirable protocol comes first.\n"
       << "                       The parameter must be delimited by a single\n"

src/shrpx_client_handler.cc

@@ -34,6 +34,7 @@
 #include "shrpx_http_downstream_connection.h"
 #include "shrpx_http2_downstream_connection.h"
 #include "shrpx_accesslog.h"
+#include "shrpx_ssl.h"
 #ifdef HAVE_SPDYLAY
 #include "shrpx_spdy_upstream.h"
 #endif // HAVE_SPDYLAY
@@ -108,7 +109,10 @@ void upstream_eventcb(bufferevent *bev, short events, void *arg)
       if(LOG_ENABLED(INFO)) {
         CLOG(INFO, handler) << "SSL/TLS handleshake completed";
       }
-      handler->validate_next_proto();
+      if(handler->validate_next_proto() != 0) {
+        delete handler;
+        return;
+      }
       if(LOG_ENABLED(INFO)) {
         if(SSL_session_reused(handler->get_ssl())) {
           CLOG(INFO, handler) << "SSL/TLS session reused";
@@ -305,6 +309,11 @@ int ClientHandler::validate_next_proto()
         std::string proto(next_proto, next_proto+next_proto_len);
         CLOG(INFO, this) << "The negotiated next protocol: " << proto;
       }
+      if(!ssl::in_proto_list(get_config()->npn_list,
+                             get_config()->npn_list_len,
+                             next_proto, next_proto_len)) {
+        break;
+      }
       if(next_proto_len == NGHTTP2_PROTO_VERSION_ID_LEN &&
          memcmp(NGHTTP2_PROTO_VERSION_ID, next_proto,
                 NGHTTP2_PROTO_VERSION_ID_LEN) == 0) {
@@ -320,6 +329,10 @@ int ClientHandler::validate_next_proto()
           return 0;
         }
 #endif // HAVE_SPDYLAY
+        if(next_proto_len == 8 && memcmp("http/1.1", next_proto, 8) == 0) {
+          upstream_ = util::make_unique<HttpsUpstream>(this);
+          return 0;
+        }
       }
       break;
     }
@@ -331,14 +344,15 @@ int ClientHandler::validate_next_proto()
   }
   if(!next_proto) {
     if(LOG_ENABLED(INFO)) {
-      CLOG(INFO, this) << "No proto negotiated.";
+      CLOG(INFO, this) << "No protocol negotiated. Fallback to HTTP/1.1";
     }
+    upstream_ = util::make_unique<HttpsUpstream>(this);
+    return 0;
   }
   if(LOG_ENABLED(INFO)) {
-    CLOG(INFO, this) << "Use HTTP/1.1";
+    CLOG(INFO, this) << "The negotiated protocol is not supported";
   }
-  upstream_ = util::make_unique<HttpsUpstream>(this);
-  return 0;
+  return -1;
 }
 
 int ClientHandler::on_read()

src/shrpx_config.h

@@ -147,8 +147,9 @@ struct Config {
   char *downstream_http_proxy_host;
   // Rate limit configuration
   ev_token_bucket_cfg *rate_limit_cfg;
-  // Comma delimited list of NPN protocol strings in the order of
-  // preference.
+  // list of supported NPN/ALPN protocol strings in the order of
+  // preference. The each element of this list is a NULL-terminated
+  // string.
   char **npn_list;
   // Path to file containing CA certificate solely used for client
   // certificate validation

src/shrpx_ssl.cc

@@ -831,6 +831,18 @@ int cert_lookup_tree_add_cert_from_file(CertLookupTree *lt, SSL_CTX *ssl_ctx,
   return 0;
 }
 
+bool in_proto_list(char **protos, size_t len,
+                   const unsigned char *proto, size_t protolen)
+{
+  for(size_t i = 0; i < len; ++i) {
+    if(strlen(protos[i]) == protolen &&
+       memcmp(protos[i], proto, protolen) == 0) {
+      return true;
+    }
+  }
+  return false;
+}
+
 } // namespace ssl
 
 } // namespace shrpx

src/shrpx_ssl.h

@@ -126,6 +126,12 @@ SSL_CTX* cert_lookup_tree_lookup(CertLookupTree *lt, const char *hostname,
 int cert_lookup_tree_add_cert_from_file(CertLookupTree *lt, SSL_CTX *ssl_ctx,
                                         const char *certfile);
 
+// Returns true if |proto| which has |protolen| bytes is included in
+// the protocol list |protos|, which has |len| elements. The format of
+// the |protos| is the one used in Config::npn_list.
+bool in_proto_list(char **protos, size_t len,
+                   const unsigned char *proto, size_t protolen);
+
 } // namespace ssl
 
 } // namespace shrpx