Handle overflow in initial window update in stream

Rename window_size in nghttp2_stream as remote_window_size.

lib/includes/nghttp2/nghttp2.h

@@ -71,6 +71,13 @@ typedef struct nghttp2_session nghttp2_session;
  */
 #define NGHTTP2_PRI_LOWEST ((1U << 31) - 1)
 
+/**
+ * @macro
+ *
+ * The maximum window size
+ */
+#define NGHTTP2_MAX_WINDOW_SIZE ((int32_t)((1U << 31) - 1))
+
 /**
  * @macro
  *
@@ -207,6 +214,10 @@ typedef enum {
    * Header block inflate/deflate error.
    */
   NGHTTP2_ERR_HEADER_COMP = -523,
+  /**
+   * Flow control error
+   */
+  NGHTTP2_ERR_FLOW_CONTROL = -524,
   /**
    * The errors < :enum:`NGHTTP2_ERR_FATAL` mean that the library is
    * under unexpected condition and cannot process any further data

lib/nghttp2_session.c

@@ -457,6 +457,8 @@ nghttp2_stream* nghttp2_session_open_stream(nghttp2_session *session,
                       [NGHTTP2_SETTINGS_FLOW_CONTROL_OPTIONS],
                       session->remote_settings
                       [NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE],
+                      session->local_settings
+                      [NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE],
                       stream_user_data);
   r = nghttp2_map_insert(&session->streams, &stream->map_entry);
   if(r != 0) {
@@ -818,7 +820,7 @@ static size_t nghttp2_session_next_data_read(nghttp2_session *session,
     int32_t session_window_size =
       session->remote_flow_control ? session->window_size : INT32_MAX;
     int32_t stream_window_size =
-      stream->remote_flow_control ? stream->window_size : INT32_MAX;
+      stream->remote_flow_control ? stream->remote_window_size : INT32_MAX;
     int32_t window_size = nghttp2_min(session_window_size,
                                       stream_window_size);
     if(window_size > 0) {
@@ -1509,7 +1511,7 @@ int nghttp2_session_send(nghttp2_session *session)
         frame = nghttp2_outbound_item_get_data_frame(session->aob.item);
         stream = nghttp2_session_get_stream(session, frame->hd.stream_id);
         if(stream && stream->remote_flow_control) {
-          stream->window_size -= len;
+          stream->remote_window_size -= len;
         }
         if(session->remote_flow_control) {
           session->window_size -= len;
@@ -1857,21 +1859,24 @@ int nghttp2_session_on_rst_stream_received(nghttp2_session *session,
 static int nghttp2_update_initial_window_size_func(nghttp2_map_entry *entry,
                                                    void *ptr)
 {
+  int rv;
   nghttp2_update_window_size_arg *arg;
   nghttp2_stream *stream;
   arg = (nghttp2_update_window_size_arg*)ptr;
   stream = (nghttp2_stream*)entry;
-  nghttp2_stream_update_initial_window_size(stream,
+  rv = nghttp2_stream_update_remote_initial_window_size(stream,
                                                         arg->new_window_size,
                                                         arg->old_window_size);
+  if(rv != 0) {
+    return NGHTTP2_ERR_FLOW_CONTROL;
+  }
   /* If window size gets positive, push deferred DATA frame to
      outbound queue. */
   if(stream->deferred_data &&
      (stream->deferred_flags & NGHTTP2_DEFERRED_FLOW_CONTROL) &&
-     stream->window_size > 0 &&
+     stream->remote_window_size > 0 &&
      (arg->session->remote_flow_control == 0 ||
       arg->session->window_size > 0)) {
-    int rv;
     rv = nghttp2_pq_push(&arg->session->ob_pq, stream->deferred_data);
     if(rv == 0) {
       nghttp2_stream_detach_deferred_data(stream);
@@ -2011,10 +2016,15 @@ int nghttp2_session_on_settings_received(nghttp2_session *session,
     case NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE:
       /* Update the initial window size of the all active streams */
       /* Check that initial_window_size < (1u << 31) */
-      if(entry->value < (1u << 31)) {
+      if(entry->value <= NGHTTP2_MAX_WINDOW_SIZE) {
         rv = nghttp2_session_update_initial_window_size(session, entry->value);
         if(rv != 0) {
+          if(nghttp2_is_fatal(rv)) {
             return rv;
+          } else {
+            return nghttp2_session_handle_invalid_connection
+              (session, frame, NGHTTP2_FLOW_CONTROL_ERROR);
+          }
         }
       } else {
         return nghttp2_session_handle_invalid_connection
@@ -2143,7 +2153,7 @@ static int nghttp2_push_back_deferred_data_func(nghttp2_map_entry *entry,
      outbound queue. */
   if(stream->deferred_data &&
      (stream->deferred_flags & NGHTTP2_DEFERRED_FLOW_CONTROL) &&
-     (stream->remote_flow_control == 0 || stream->window_size > 0)) {
+     (stream->remote_flow_control == 0 || stream->remote_window_size > 0)) {
     int rv;
     rv = nghttp2_pq_push(&session->ob_pq, stream->deferred_data);
     if(rv == 0) {
@@ -2232,15 +2242,16 @@ int nghttp2_session_on_window_update_received(nghttp2_session *session,
         nghttp2_session_call_on_frame_received(session, frame);
         return 0;
       }
-      if(INT32_MAX - frame->window_update.window_size_increment <
-         stream->window_size) {
+      if(NGHTTP2_MAX_WINDOW_SIZE - frame->window_update.window_size_increment <
+         stream->remote_window_size) {
         int r;
         r = nghttp2_session_handle_invalid_stream
           (session, frame, NGHTTP2_FLOW_CONTROL_ERROR);
         return r;
       } else {
-        stream->window_size += frame->window_update.window_size_increment;
-        if(stream->window_size > 0 &&
+        stream->remote_window_size +=
+          frame->window_update.window_size_increment;
+        if(stream->remote_window_size > 0 &&
            (session->remote_flow_control == 0 ||
             session->window_size > 0) &&
            stream->deferred_data != NULL &&

lib/nghttp2_stream.c

@@ -31,7 +31,8 @@ void nghttp2_stream_init(nghttp2_stream *stream, int32_t stream_id,
                          nghttp2_stream_state initial_state,
                          uint8_t remote_flow_control,
                          uint8_t local_flow_control,
-                         int32_t initial_window_size,
+                         int32_t remote_initial_window_size,
+                         int32_t local_initial_window_size,
                          void *stream_user_data)
 {
   nghttp2_map_entry_init(&stream->map_entry, stream_id);
@@ -45,7 +46,8 @@ void nghttp2_stream_init(nghttp2_stream *stream, int32_t stream_id,
   stream->deferred_flags = NGHTTP2_DEFERRED_NONE;
   stream->remote_flow_control = remote_flow_control;
   stream->local_flow_control = local_flow_control;
-  stream->window_size = initial_window_size;
+  stream->remote_window_size = remote_initial_window_size;
+  stream->local_window_size = local_initial_window_size;
   stream->recv_window_size = 0;
 }
 
@@ -75,12 +77,20 @@ void nghttp2_stream_detach_deferred_data(nghttp2_stream *stream)
   stream->deferred_flags = NGHTTP2_DEFERRED_NONE;
 }
 
-void nghttp2_stream_update_initial_window_size(nghttp2_stream *stream,
+int nghttp2_stream_update_remote_initial_window_size
+(nghttp2_stream *stream,
  int32_t new_initial_window_size,
  int32_t old_initial_window_size)
 {
-  stream->window_size =
-    new_initial_window_size-(old_initial_window_size-stream->window_size);
+  int64_t new_window_size = (int64_t)stream->remote_window_size +
+    new_initial_window_size - old_initial_window_size;
+  if(INT32_MIN > new_window_size ||
+     new_window_size > NGHTTP2_MAX_WINDOW_SIZE) {
+    return -1;
+  }
+  stream->remote_window_size +=
+    new_initial_window_size - old_initial_window_size;
+  return 0;
 }
 
 void nghttp2_stream_promise_fulfilled(nghttp2_stream *stream)

lib/nghttp2_stream.h

@@ -109,12 +109,16 @@ typedef struct {
      flow control options off or sending WINDOW_UPDATE with
      END_FLOW_CONTROL bit set. */
   uint8_t local_flow_control;
-  /* Current sender window size. This value is computed against the
+  /* Current remote window size. This value is computed against the
      current initial window size of remote endpoint. */
-  int32_t window_size;
+  int32_t remote_window_size;
   /* Keep track of the number of bytes received without
      WINDOW_UPDATE. */
   int32_t recv_window_size;
+  /* window size for local window control. It is initially set to
+     NGHTTP2_INITIAL_WINDOW_SIZE and could be increased/decreased by
+     submitting WINDOW_UPDATE. See nghttp2_submit_window_update(). */
+  int32_t local_window_size;
 } nghttp2_stream;
 
 void nghttp2_stream_init(nghttp2_stream *stream, int32_t stream_id,
@@ -122,7 +126,8 @@ void nghttp2_stream_init(nghttp2_stream *stream, int32_t stream_id,
                          nghttp2_stream_state initial_state,
                          uint8_t remote_flow_control,
                          uint8_t local_flow_control,
-                         int32_t initial_window_size,
+                         int32_t remote_initial_window_size,
+                         int32_t local_initial_window_size,
                          void *stream_user_data);
 
 void nghttp2_stream_free(nghttp2_stream *stream);
@@ -149,11 +154,15 @@ void nghttp2_stream_defer_data(nghttp2_stream *stream,
 void nghttp2_stream_detach_deferred_data(nghttp2_stream *stream);
 
 /*
- * Updates the initial window size with the new value
+ * Updates the remote window size with the new value
  * |new_initial_window_size|. The |old_initial_window_size| is used to
  * calculate the current window size.
+ *
+ * This function returns 0 if it succeeds or -1. The failure is due to
+ * overflow.
  */
-void nghttp2_stream_update_initial_window_size(nghttp2_stream *stream,
+int nghttp2_stream_update_remote_initial_window_size
+(nghttp2_stream *stream,
  int32_t new_initial_window_size,
  int32_t old_initial_window_size);
 

tests/nghttp2_session_test.c

@@ -906,8 +906,8 @@ void test_nghttp2_session_on_settings_received(void)
                                         NGHTTP2_STREAM_OPENING, NULL);
   /* Set window size for each streams and will see how settings
      updates these values */
-  stream1->window_size = 16*1024;
-  stream2->window_size = -48*1024;
+  stream1->remote_window_size = 16*1024;
+  stream2->remote_window_size = -48*1024;
 
   nghttp2_frame_settings_init(&frame.settings, dup_iv(iv, niv), niv);
 
@@ -919,15 +919,15 @@ void test_nghttp2_session_on_settings_received(void)
   CU_ASSERT(1 ==
             session->remote_settings[NGHTTP2_SETTINGS_FLOW_CONTROL_OPTIONS]);
 
-  CU_ASSERT(64*1024 == stream1->window_size);
-  CU_ASSERT(0 == stream2->window_size);
+  CU_ASSERT(64*1024 == stream1->remote_window_size);
+  CU_ASSERT(0 == stream2->remote_window_size);
 
   frame.settings.iv[2].value = 16*1024;
 
   CU_ASSERT(0 == nghttp2_session_on_settings_received(session, &frame));
 
-  CU_ASSERT(16*1024 == stream1->window_size);
-  CU_ASSERT(-48*1024 == stream2->window_size);
+  CU_ASSERT(16*1024 == stream1->remote_window_size);
+  CU_ASSERT(-48*1024 == stream2->remote_window_size);
 
   CU_ASSERT(0 == stream1->remote_flow_control);
   CU_ASSERT(0 == stream2->remote_flow_control);
@@ -1141,7 +1141,7 @@ void test_nghttp2_session_on_window_update_received(void)
 
   CU_ASSERT(0 == nghttp2_session_on_window_update_received(session, &frame));
   CU_ASSERT(1 == user_data.frame_recv_cb_called);
-  CU_ASSERT(NGHTTP2_INITIAL_WINDOW_SIZE+16*1024 == stream->window_size);
+  CU_ASSERT(NGHTTP2_INITIAL_WINDOW_SIZE+16*1024 == stream->remote_window_size);
 
   data_item = malloc(sizeof(nghttp2_outbound_item));
   memset(data_item, 0, sizeof(nghttp2_outbound_item));
@@ -1150,7 +1150,8 @@ void test_nghttp2_session_on_window_update_received(void)
 
   CU_ASSERT(0 == nghttp2_session_on_window_update_received(session, &frame));
   CU_ASSERT(2 == user_data.frame_recv_cb_called);
-  CU_ASSERT(NGHTTP2_INITIAL_WINDOW_SIZE+16*1024*2 == stream->window_size);
+  CU_ASSERT(NGHTTP2_INITIAL_WINDOW_SIZE+16*1024*2 ==
+            stream->remote_window_size);
   CU_ASSERT(NULL == stream->deferred_data);
 
   nghttp2_frame_window_update_free(&frame.window_update);
@@ -2475,12 +2476,12 @@ void test_nghttp2_session_flow_control(void)
   /* Change initial window size to 16KiB. The window_size becomes
      negative. */
   new_initial_window_size = 16*1024;
-  stream->window_size = new_initial_window_size-
+  stream->remote_window_size = new_initial_window_size-
     (session->remote_settings[NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE]
-     -stream->window_size);
+     - stream->remote_window_size);
   session->remote_settings[NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE] =
     new_initial_window_size;
-  CU_ASSERT(-48*1024 == stream->window_size);
+  CU_ASSERT(-48*1024 == stream->remote_window_size);
 
   /* Back 48KiB to stream window */
   frame.hd.stream_id = 1;