[PATCH] SPDY: stop emitting empty header values

[Valentin V. Bartenev]

On Tuesday 21 October 2014 04:16:01 Piotr Sikora wrote:
> # 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;
>          }
> 


IMHO, there is no need to introduce "sep" variable:

diff -r a8d111bb6884 src/http/ngx_http_spdy_filter_module.c
--- a/src/http/ngx_http_spdy_filter_module.c    Tue Sep 30 17:20:32 2014 +0400                                                                         
+++ b/src/http/ngx_http_spdy_filter_module.c    Mon Oct 27 16:58:02 2014 +0300                                                                         
@@ -493,9 +493,13 @@ ngx_http_spdy_header_filter(ngx_http_req                                                                                          
                 continue;                                                                                                                             
             }                                                                                                                                         
                                                                                                                                                       
-            *last++ = '\0';                                                                                                                           
+            if (h[j].value.len) {                                                                                                                     
+                if (last != p) {                                                                                                                      
+                    *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);                                                                             
+            }                                                                                                                                         
                                                                                                                                                       
             h[j].hash = 2;                                                                                                                            
         }