http2: handle GOAWAY properly

When receiving REFUSED_STREAM, mark the connection for close and retry
streams accordingly on another/fresh connection.

Reported-by: Terry Wu
Fixes #2416
Fixes #1618
Closes #2510

lib/http2.c

@@ -1106,7 +1106,6 @@ void Curl_http2_done(struct connectdata *conn, bool premature)
   struct http_conn *httpc = &conn->proto.httpc;
 
   if(http->header_recvbuf) {
-    H2BUGF(infof(data, "free header_recvbuf!!\n"));
     Curl_add_buffer_free(http->header_recvbuf);
     http->header_recvbuf = NULL; /* clear the pointer */
     Curl_add_buffer_free(http->trailer_recvbuf);
@@ -1376,7 +1375,15 @@ static ssize_t http2_handle_stream_close(struct connectdata *conn,
 
   /* Reset to FALSE to prevent infinite loop in readwrite_data function. */
   stream->closed = FALSE;
-  if(httpc->error_code != NGHTTP2_NO_ERROR) {
+  if(httpc->error_code == NGHTTP2_REFUSED_STREAM) {
+    H2BUGF(infof(data, "REFUSED_STREAM (%d), try again on a new connection!\n",
+                 stream->stream_id));
+    connclose(conn, "REFUSED_STREAM"); /* don't use this anymore */
+    data->state.refused_stream = TRUE;
+    *err = CURLE_RECV_ERROR; /* trigger Curl_retry_request() later */
+    return -1;
+  }
+  else if(httpc->error_code != NGHTTP2_NO_ERROR) {
     failf(data, "HTTP/2 stream %u was not closed cleanly: %s (err %d)",
           stream->stream_id, Curl_http2_strerror(httpc->error_code),
           httpc->error_code);
@@ -1604,9 +1611,9 @@ static ssize_t http2_recv(struct connectdata *conn, int sockindex,
       }
 
       if(nread == 0) {
-        failf(data, "Unexpected EOF");
-        *err = CURLE_RECV_ERROR;
-        return -1;
+        H2BUGF(infof(data, "end of stream\n"));
+        *err = CURLE_OK;
+        return 0;
       }
 
       H2BUGF(infof(data, "nread=%zd\n", nread));

lib/multi.c

@@ -546,7 +546,9 @@ static CURLcode multi_done(struct connectdata **connp,
   if(conn->send_pipe.size || conn->recv_pipe.size) {
     /* Stop if pipeline is not empty . */
     data->easy_conn = NULL;
-    DEBUGF(infof(data, "Connection still in use, no more multi_done now!\n"));
+    DEBUGF(infof(data, "Connection still in use %d/%d, "
+                 "no more multi_done now!\n",
+                 conn->send_pipe.size, conn->recv_pipe.size));
     return CURLE_OK;
   }
 

lib/transfer.c

@@ -1926,7 +1926,7 @@ CURLcode Curl_retry_request(struct connectdata *conn,
                             char **url)
 {
   struct Curl_easy *data = conn->data;
-
+  bool retry = FALSE;
   *url = NULL;
 
   /* if we're talking upload, we can't do the checks below, unless the protocol
@@ -1939,7 +1939,7 @@ CURLcode Curl_retry_request(struct connectdata *conn,
       conn->bits.reuse &&
       (!data->set.opt_no_body
         || (conn->handler->protocol & PROTO_FAMILY_HTTP)) &&
-      (data->set.rtspreq != RTSPREQ_RECEIVE)) {
+      (data->set.rtspreq != RTSPREQ_RECEIVE))
     /* We got no data, we attempted to re-use a connection. For HTTP this
        can be a retry so we try again regardless if we expected a body.
        For other protocols we only try again only if we expected a body.
@@ -1947,6 +1947,19 @@ CURLcode Curl_retry_request(struct connectdata *conn,
        This might happen if the connection was left alive when we were
        done using it before, but that was closed when we wanted to read from
        it again. Bad luck. Retry the same request on a fresh connect! */
+    retry = TRUE;
+  else if(data->state.refused_stream &&
+          (data->req.bytecount + data->req.headerbytecount == 0) ) {
+    /* This was sent on a refused stream, safe to rerun. A refused stream
+       error can typically only happen on HTTP/2 level if the stream is safe
+       to issue again, but the nghttp2 API can deliver the message to other
+       streams as well, which is why this adds the check the data counters
+       too. */
+    infof(conn->data, "REFUSED_STREAM, retrying a fresh connect\n");
+    data->state.refused_stream = FALSE; /* clear again */
+    retry = TRUE;
+  }
+  if(retry) {
     infof(conn->data, "Connection died, retrying a fresh connect\n");
     *url = strdup(conn->data->change.url);
     if(!*url)

lib/urldata.h

@@ -1226,7 +1226,7 @@ struct UrlState {
   curl_off_t current_speed;  /* the ProgressShow() function sets this,
                                 bytes / second */
   bool this_is_a_follow; /* this is a followed Location: request */
-
+  bool refused_stream; /* this was refused, try again */
   char *first_host; /* host name of the first (not followed) request.
                        if set, this should be the host name that we will
                        sent authorization to, no else. Used to make Location: