[PATCH] SPDY: stop emitting empty header values

[Piotr Sikora]

# HG changeset patch
# User Piotr Sikora <piotr at cloudflare.com>
# Date 1413890111 25200
#      Tue Oct 21 04:15:11 2014 -0700
# Node ID fbc2eb84bd266b64644b00a6454c4f79f241af5a
# Parent  973fded4f461f3a397779b3a1dc80881b1b34974
SPDY: stop emitting empty header values.

Previously, nginx would emit empty values in a header with multiple,
NULL-separated values.

This is forbidden by the SPDY specification, which requires headers to
have either a single (possibly empty) value or multiple, NULL-separated
non-empty values.

Signed-off-by: Piotr Sikora <piotr at cloudflare.com>

diff -r 973fded4f461 -r fbc2eb84bd26 src/http/ngx_http_spdy_filter_module.c
--- a/src/http/ngx_http_spdy_filter_module.c	Wed Oct 15 22:57:23 2014 +0400
+++ b/src/http/ngx_http_spdy_filter_module.c	Tue Oct 21 04:15:11 2014 -0700
@@ -100,7 +100,7 @@ ngx_http_spdy_header_filter(ngx_http_req
     u_char                       *p, *buf, *last;
     ngx_buf_t                    *b;
     ngx_str_t                     host;
-    ngx_uint_t                    i, j, count, port;
+    ngx_uint_t                    i, j, count, port, sep;
     ngx_chain_t                  *cl;
     ngx_list_part_t              *part, *pt;
     ngx_table_elt_t              *header, *h;
@@ -472,6 +472,7 @@ ngx_http_spdy_header_filter(ngx_http_req
 
         pt = part;
         h = header;
+        sep = header[i].value.len ? 1 : 0;
 
         for (j = i + 1; /* void */; j++) {
 
@@ -493,9 +494,14 @@ ngx_http_spdy_header_filter(ngx_http_req
                 continue;
             }
 
-            *last++ = '\0';
+            if (h[j].value.len) {
+                if (sep) {
+                    *last++ = '\0';
+                }
 
-            last = ngx_cpymem(last, h[j].value.data, h[j].value.len);
+                last = ngx_cpymem(last, h[j].value.data, h[j].value.len);
+                sep = 1;
+            }
 
             h[j].hash = 2;
         }