http2: Read data left in connection buffer after pause

Previously when we do pause because of out of buffer, we just throw
away unread data in connection buffer.  This just broke protocol
framing, and I saw occasional FRAME_SIZE_ERROR.  This commit fix this
issue by remembering how much data read, and in the next iteration, we
process remaining data.

1 files changed, 44 insertions, 20 deletions

diff --git a/lib/http2.c b/lib/http2.c
index 521a78106..78a09af8e 100644
--- a/lib/http2.c
+++ b/lib/http2.c
@@ -859,36 +859,47 @@ static ssize_t http2_recv(struct connectdata *conn, int sockindex,
     }
   }
   else {
+    char *inbuf;
     /* remember where to store incoming data for this stream and how big the
        buffer is */
     stream->mem = mem;
     stream->len = len;
     stream->memlen = 0;
 
-    nread = ((Curl_recv*)httpc->recv_underlying)(conn, FIRSTSOCKET,
-                                                 httpc->inbuf, H2_BUFSIZE,
-                                                 &result);
-    if(result == CURLE_AGAIN) {
-      *err = result;
-      return -1;
-    }
+    if(httpc->inbuflen == 0) {
+      nread = ((Curl_recv *)httpc->recv_underlying)(
+          conn, FIRSTSOCKET, httpc->inbuf, H2_BUFSIZE, &result);
 
-    if(nread == -1) {
-      failf(data, "Failed receiving HTTP2 data");
-      *err = result;
-      return 0;
-    }
+      if(result == CURLE_AGAIN) {
+        *err = result;
+        return -1;
+      }
 
-    if(nread == 0) {
-      failf(data, "Unexpected EOF");
-      *err = CURLE_RECV_ERROR;
-      return -1;
-    }
+      if(nread == -1) {
+        failf(data, "Failed receiving HTTP2 data");
+        *err = result;
+        return 0;
+      }
 
-    DEBUGF(infof(data, "nread=%zd\n", nread));
+      if(nread == 0) {
+        failf(data, "Unexpected EOF");
+        *err = CURLE_RECV_ERROR;
+        return -1;
+      }
 
-    rv = nghttp2_session_mem_recv(httpc->h2,
-                                  (const uint8_t *)httpc->inbuf, nread);
+      DEBUGF(infof(data, "nread=%zd\n", nread));
+
+      httpc->inbuflen = nread;
+      inbuf = httpc->inbuf;
+    }
+    else {
+      nread = httpc->inbuflen - httpc->nread_inbuf;
+      inbuf = httpc->inbuf + httpc->nread_inbuf;
+
+      DEBUGF(infof(data, "Use data left in connection buffer, nread=%zd\n",
+                   nread));
+    }
+    rv = nghttp2_session_mem_recv(httpc->h2, (const uint8_t *)inbuf, nread);
 
     if(nghttp2_is_fatal((int)rv)) {
       failf(data, "nghttp2_session_mem_recv() returned %d:%s\n",
@@ -897,6 +908,16 @@ static ssize_t http2_recv(struct connectdata *conn, int sockindex,
       return 0;
     }
     DEBUGF(infof(data, "nghttp2_session_mem_recv() returns %zd\n", rv));
+    if(nread == rv) {
+      DEBUGF(infof(data, "All data in connection buffer processed\n"));
+      httpc->inbuflen = 0;
+      httpc->nread_inbuf = 0;
+    }
+    else {
+      httpc->nread_inbuf += rv;
+      DEBUGF(infof(data, "%zu bytes left in connection buffer\n",
+                   httpc->inbuflen - httpc->nread_inbuf));
+    }
     /* Always send pending frames in nghttp2 session, because
        nghttp2_session_mem_recv() may queue new frame */
     rv = nghttp2_session_send(httpc->h2);
@@ -1145,6 +1166,9 @@ CURLcode Curl_http2_setup(struct connectdata *conn)
   httpc->upload_mem = NULL;
   httpc->upload_len = 0;
 
+  httpc->inbuflen = 0;
+  httpc->nread_inbuf = 0;
+
   conn->bits.multiplex = TRUE; /* at least potentially multiplexed */
   conn->httpversion = 20;
   conn->bundle->server_supports_pipelining = TRUE;