Ignore unknown frame types

Unexpected CONTINUATION frame is handled separately as connection
error.

lib/nghttp2_session.c

@@ -4456,6 +4456,22 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session,
         iframe->state = NGHTTP2_IB_READ_NBYTE;
         inbound_frame_set_mark(iframe, 8);
 
+        break;
+      case NGHTTP2_CONTINUATION:
+        DEBUGF(fprintf(stderr, "recv: unexpected CONTINUATION\n"));
+
+        /* Receiving CONTINUATION in this state are subject to
+           connection error of type PROTOCOL_ERROR */
+        rv = nghttp2_session_terminate_session(session,
+                                               NGHTTP2_PROTOCOL_ERROR);
+        if(nghttp2_is_fatal(rv)) {
+          return rv;
+        }
+
+        busy = 1;
+
+        iframe->state = NGHTTP2_IB_IGN_PAYLOAD;
+
         break;
       case NGHTTP2_ALTSVC:
         DEBUGF(fprintf(stderr, "recv: ALTSVC\n"));
@@ -4512,13 +4528,7 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session,
       default:
         DEBUGF(fprintf(stderr, "recv: unknown frame\n"));
 
-        /* Receiving unknown frame type and CONTINUATION in this state
+        /* Silently ignore unknown frame type. */
-           are subject to connection error of type PROTOCOL_ERROR */
-        rv = nghttp2_session_terminate_session(session,
-                                               NGHTTP2_PROTOCOL_ERROR);
-        if(nghttp2_is_fatal(rv)) {
-          return rv;
-        }
 
         busy = 1;
 
@@ -4849,6 +4859,7 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session,
       switch(iframe->frame.hd.type) {
       case NGHTTP2_HEADERS:
       case NGHTTP2_PUSH_PROMISE:
+      case NGHTTP2_CONTINUATION:
         /* Mark inflater bad so that we won't perform further decoding */
         session->hd_inflater.ctx.bad = 1;
         break;

tests/main.c

@@ -89,6 +89,10 @@ int main(int argc, char* argv[])
                    test_nghttp2_session_recv_premature_headers) ||
       !CU_add_test(pSuite, "session_recv_altsvc",
                    test_nghttp2_session_recv_altsvc) ||
+      !CU_add_test(pSuite, "session_recv_unknown_frame",
+                   test_nghttp2_session_recv_unknown_frame) ||
+      !CU_add_test(pSuite, "session_recv_unexpected_continuation",
+                   test_nghttp2_session_recv_unexpected_continuation) ||
       !CU_add_test(pSuite, "session_continue", test_nghttp2_session_continue) ||
       !CU_add_test(pSuite, "session_add_frame",
                    test_nghttp2_session_add_frame) ||

tests/nghttp2_session_test.c

@@ -1146,6 +1146,82 @@ void test_nghttp2_session_recv_altsvc(void)
   nghttp2_session_del(session);
 }
 
+void test_nghttp2_session_recv_unknown_frame(void)
+{
+  nghttp2_session *session;
+  nghttp2_session_callbacks callbacks;
+  my_user_data ud;
+  uint8_t data[16384];
+  size_t datalen;
+  nghttp2_frame_hd hd;
+  ssize_t rv;
+
+  hd.length = 16000;
+  hd.stream_id = 0;
+  hd.type = 99;
+  hd.flags = NGHTTP2_FLAG_NONE;
+
+  nghttp2_frame_pack_frame_hd(data, &hd);
+  datalen = NGHTTP2_FRAME_HDLEN + hd.length;
+
+  memset(&callbacks, 0, sizeof(nghttp2_session_callbacks));
+  callbacks.on_frame_recv_callback = on_frame_recv_callback;
+
+  nghttp2_session_server_new(&session, &callbacks, &ud);
+
+  ud.frame_recv_cb_called = 0;
+
+  /* Unknown frame must be ignored */
+  rv = nghttp2_session_mem_recv(session, data, datalen);
+
+  CU_ASSERT(rv == (ssize_t)datalen);
+  CU_ASSERT(0 == ud.frame_recv_cb_called);
+  CU_ASSERT(NULL == nghttp2_session_get_next_ob_item(session));
+
+  nghttp2_session_del(session);
+}
+
+void test_nghttp2_session_recv_unexpected_continuation(void)
+{
+  nghttp2_session *session;
+  nghttp2_session_callbacks callbacks;
+  my_user_data ud;
+  uint8_t data[16384];
+  size_t datalen;
+  nghttp2_frame_hd hd;
+  ssize_t rv;
+  nghttp2_outbound_item *item;
+
+  hd.length = 16000;
+  hd.stream_id = 1;
+  hd.type = NGHTTP2_CONTINUATION;
+  hd.flags = NGHTTP2_FLAG_END_HEADERS;
+
+  nghttp2_frame_pack_frame_hd(data, &hd);
+  datalen = NGHTTP2_FRAME_HDLEN + hd.length;
+
+  memset(&callbacks, 0, sizeof(nghttp2_session_callbacks));
+  callbacks.on_frame_recv_callback = on_frame_recv_callback;
+
+  nghttp2_session_server_new(&session, &callbacks, &ud);
+
+  open_stream(session, 1);
+
+  ud.frame_recv_cb_called = 0;
+
+  /* unexpected CONTINUATION must be treated as connection error */
+  rv = nghttp2_session_mem_recv(session, data, datalen);
+
+  CU_ASSERT(rv == (ssize_t)datalen);
+  CU_ASSERT(0 == ud.frame_recv_cb_called);
+
+  item = nghttp2_session_get_next_ob_item(session);
+
+  CU_ASSERT(NGHTTP2_GOAWAY == OB_CTRL_TYPE(item));
+
+  nghttp2_session_del(session);
+}
+
 void test_nghttp2_session_continue(void)
 {
   nghttp2_session *session;

tests/nghttp2_session_test.h

@@ -34,6 +34,8 @@ void test_nghttp2_session_recv_continuation(void);
 void test_nghttp2_session_recv_headers_with_priority(void);
 void test_nghttp2_session_recv_premature_headers(void);
 void test_nghttp2_session_recv_altsvc(void);
+void test_nghttp2_session_recv_unknown_frame(void);
+void test_nghttp2_session_recv_unexpected_continuation(void);
 void test_nghttp2_session_continue(void);
 void test_nghttp2_session_add_frame(void);
 void test_nghttp2_session_on_request_headers_received(void);