[nginx] SPDY: consistently handle control frames with unknown type.

[Valentin Bartenev]

details:   http://hg.nginx.org/nginx/rev/436f3605195a
branches:  
changeset: 5643:436f3605195a
user:      Valentin Bartenev <vbart at nginx.com>
date:      Mon Apr 07 19:27:56 2014 +0400
description:
SPDY: consistently handle control frames with unknown type.

The SPDY draft 2 specification requires that if an endpoint receives a
control frame for a type it does not recognize, it must ignore the frame.
But the 3 and 3.1 drafts don't seem to declare any behavior for such case.
Then sticking with the previous draft in this matter looks to be right.

But previously, only 8 least significant bits of the type field were
parsed while the rest of 16 bits of the field were checked against zero.
Though there are no known frame types bigger than 255, this resulted in
inconsistency in handling of such frames: they were not recognized as
valid frames at all, and the connection was closed.

diffstat:

 src/http/ngx_http_spdy.c |  15 ++++++++++-----
 1 files changed, 10 insertions(+), 5 deletions(-)

diffs (49 lines):

diff -r d2ac5cf4056d -r 436f3605195a src/http/ngx_http_spdy.c
--- a/src/http/ngx_http_spdy.c	Mon Apr 07 19:27:56 2014 +0400
+++ b/src/http/ngx_http_spdy.c	Mon Apr 07 19:27:56 2014 +0400
@@ -47,11 +47,11 @@
 
 
 #define ngx_spdy_ctl_frame_check(h)                                           \
-    (((h) & 0xffffff00) == ngx_spdy_ctl_frame_head(0))
+    (((h) & 0xffff0000) == ngx_spdy_ctl_frame_head(0))
 #define ngx_spdy_data_frame_check(h)                                          \
     (!((h) & (uint32_t) NGX_SPDY_CTL_BIT << 31))
 
-#define ngx_spdy_ctl_frame_type(h)   ((h) & 0x000000ff)
+#define ngx_spdy_ctl_frame_type(h)   ((h) & 0x0000ffff)
 #define ngx_spdy_frame_flags(p)      ((p) >> 24)
 #define ngx_spdy_frame_length(p)     ((p) & 0x00ffffff)
 #define ngx_spdy_frame_id(p)         ((p) & 0x00ffffff)
@@ -836,7 +836,8 @@ static u_char *
 ngx_http_spdy_state_head(ngx_http_spdy_connection_t *sc, u_char *pos,
     u_char *end)
 {
-    uint32_t  head, flen;
+    uint32_t    head, flen;
+    ngx_uint_t  type;
 
     if (end - pos < NGX_SPDY_FRAME_HEADER_SIZE) {
         return ngx_http_spdy_state_save(sc, pos, end,
@@ -859,7 +860,9 @@ ngx_http_spdy_state_head(ngx_http_spdy_c
                    head, sc->flags, sc->length);
 
     if (ngx_spdy_ctl_frame_check(head)) {
-        switch (ngx_spdy_ctl_frame_type(head)) {
+        type = ngx_spdy_ctl_frame_type(head);
+
+        switch (type) {
 
         case NGX_SPDY_SYN_STREAM:
             return ngx_http_spdy_state_syn_stream(sc, pos, end);
@@ -885,7 +888,9 @@ ngx_http_spdy_state_head(ngx_http_spdy_c
         case NGX_SPDY_WINDOW_UPDATE:
             return ngx_http_spdy_state_window_update(sc, pos, end);
 
-        default: /* TODO logging */
+        default:
+            ngx_log_debug1(NGX_LOG_DEBUG_HTTP, sc->connection->log, 0,
+                           "spdy control frame with unknown type %ui", type);
             return ngx_http_spdy_state_skip(sc, pos, end);
         }
     }