MEDIUM: h2: produce some logs on early errors that prevent streams from being created

The h2 mux currently lacks some basic transparency. Some errors cause the
connection to be aborted but they couldn't be reported. With this patch,
almost all situations where an error will cause a stream or connection to
be aborted without the ability for an existing stream to report it will be
reported in the logs. This at least provides a solution to monitor the
activity and abnormal traffic.

diff --git a/src/mux_h2.c b/src/mux_h2.c
index f7e327e0798f4d0b5eae204373c4fd87474f96d6..70a14218b6250d98746642a2bd4566e870de5417 100644 (file)
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -705,6 +705,7 @@ static struct h2s *h2c_stream_new(struct h2c *h2c, int id)
  out_close:
        h2s_destroy(h2s);
        h2s = NULL;
+       sess_log(sess);
  out:
        return h2s;
 }
@@ -802,6 +803,9 @@ static int h2c_frt_recv_preface(struct h2c *h2c)
        ret1 = b_isteq(&h2c->dbuf, 0, b_data(&h2c->dbuf), ist(H2_CONN_PREFACE));
 
        if (unlikely(ret1 <= 0)) {
+               if (ret1 < 0)
+                       sess_log(h2c->conn->owner);
+
                if (ret1 < 0 || conn_xprt_read0_pending(h2c->conn))
                        h2c_error(h2c, H2_ERR_PROTOCOL_ERROR);
                return 0;
@@ -1192,6 +1196,7 @@ static int h2c_handle_settings(struct h2c *h2c)
        h2c->st0 = H2_CS_FRAME_A;
        return 1;
  fail:
+       sess_log(h2c->conn->owner);
        h2c_error(h2c, error);
        return 0;
 }
@@ -1588,6 +1593,7 @@ static struct h2s *h2c_frt_handle_headers(struct h2c *h2c, struct h2s *h2s)
 
        if (!h2c->dfl) {
                error = H2_ERR_PROTOCOL_ERROR; // empty headers frame!
+               sess_log(h2c->conn->owner);
                goto strm_err;
        }
 
@@ -1606,14 +1612,20 @@ static struct h2s *h2c_frt_handle_headers(struct h2c *h2c, struct h2s *h2s)
                 * trailers (not supported for now).
                 */
                error = H2_ERR_PROTOCOL_ERROR;
+               sess_log(h2c->conn->owner);
                goto conn_err;
        }
        else if (h2c->dsi <= h2c->max_id || !(h2c->dsi & 1)) {
                /* RFC7540#5.1.1 stream id > prev ones, and must be odd here */
                error = H2_ERR_PROTOCOL_ERROR;
+               sess_log(h2c->conn->owner);
                goto conn_err;
        }
 
+       /* Note: we don't emit any other logs below because ff we return
+        * positively from h2c_stream_new(), the stream will report the error,
+        * and if we return in error, h2c_stream_new() will emit the error.
+        */
        h2s = h2c_stream_new(h2c, h2c->dsi);
        if (!h2s) {
                error = H2_ERR_INTERNAL_ERROR;
@@ -1752,8 +1764,10 @@ static void h2_process_demux(struct h2c *h2c)
                if (h2c->st0 == H2_CS_PREFACE) {
                        if (unlikely(h2c_frt_recv_preface(h2c) <= 0)) {
                                /* RFC7540#3.5: a GOAWAY frame MAY be omitted */
-                               if (h2c->st0 == H2_CS_ERROR)
+                               if (h2c->st0 == H2_CS_ERROR) {
                                        h2c->st0 = H2_CS_ERROR2;
+                                       sess_log(h2c->conn->owner);
+                               }
                                goto fail;
                        }
 
@@ -1769,8 +1783,10 @@ static void h2_process_demux(struct h2c *h2c)
                         */
                        if (!h2_get_frame_hdr(&h2c->dbuf, &hdr)) {
                                /* RFC7540#3.5: a GOAWAY frame MAY be omitted */
-                               if (h2c->st0 == H2_CS_ERROR)
+                               if (h2c->st0 == H2_CS_ERROR) {
                                        h2c->st0 = H2_CS_ERROR2;
+                                       sess_log(h2c->conn->owner);
+                               }
                                goto fail;
                        }
 
@@ -1778,6 +1794,7 @@ static void h2_process_demux(struct h2c *h2c)
                                /* RFC7540#3.5: a GOAWAY frame MAY be omitted */
                                h2c_error(h2c, H2_ERR_PROTOCOL_ERROR);
                                h2c->st0 = H2_CS_ERROR2;
+                               sess_log(h2c->conn->owner);
                                goto fail;
                        }
 
@@ -1785,6 +1802,7 @@ static void h2_process_demux(struct h2c *h2c)
                                /* RFC7540#3.5: a GOAWAY frame MAY be omitted */
                                h2c_error(h2c, H2_ERR_FRAME_SIZE_ERROR);
                                h2c->st0 = H2_CS_ERROR2;
+                               sess_log(h2c->conn->owner);
                                goto fail;
                        }
 
@@ -1814,6 +1832,10 @@ static void h2_process_demux(struct h2c *h2c)
                        if ((int)hdr.len < 0 || (int)hdr.len > global.tune.bufsize) {
                                h2c_error(h2c, H2_ERR_FRAME_SIZE_ERROR);
                                h2c->st0 = H2_CS_ERROR;
+                               if (!h2c->nb_streams) {
+                                       /* only log if no other stream can report the error */
+                                       sess_log(h2c->conn->owner);
+                               }
                                break;
                        }
 
@@ -1858,6 +1880,10 @@ static void h2_process_demux(struct h2c *h2c)
                         */
                        h2c_error(h2c, H2_ERR_PROTOCOL_ERROR);
                        h2c->st0 = H2_CS_ERROR;
+                       if (!h2c->nb_streams) {
+                               /* only log if no other stream can report the error */
+                               sess_log(h2c->conn->owner);
+                       }
                        break;
                }
 
@@ -2026,6 +2052,10 @@ static void h2_process_demux(struct h2c *h2c)
                case H2_FT_PUSH_PROMISE:
                        /* not permitted here, RFC7540#5.1 */
                        h2c_error(h2c, H2_ERR_PROTOCOL_ERROR);
+                       if (!h2c->nb_streams) {
+                               /* only log if no other stream can report the error */
+                               sess_log(h2c->conn->owner);
+                       }
                        break;
 
                        /* implement all extra frame types here */