[PATCH] HTTP/2: add debug logging of control frames

[Valentin V. Bartenev]

On Monday 03 April 2017 20:13:40 Piotr Sikora via nginx-devel wrote:
> # HG changeset patch
> # User Piotr Sikora <piotrsikora at google.com>
> # Date 1490516711 25200
> #      Sun Mar 26 01:25:11 2017 -0700
> # Node ID 06d6418afe6e73604aea707ef9c5802f5bf27bf4
> # Parent  22be63bf21edaa1b8ea916c7d8cd4e5fe4892061
> HTTP/2: add debug logging of control frames.
> 
> Signed-off-by: Piotr Sikora <piotrsikora at google.com>
> 
> diff -r 22be63bf21ed -r 06d6418afe6e src/http/v2/ngx_http_v2.c
> --- a/src/http/v2/ngx_http_v2.c
> +++ b/src/http/v2/ngx_http_v2.c
[..]
> @@ -2449,8 +2468,18 @@ ngx_http_v2_send_settings(ngx_http_v2_co
>      ngx_http_v2_srv_conf_t   *h2scf;
>      ngx_http_v2_out_frame_t  *frame;
>  
> -    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, h2c->connection->log, 0,
> -                   "http2 send SETTINGS frame ack:%ui", ack);
> +    if (ack) {
> +        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, h2c->connection->log, 0,
> +                       "http2 send SETTINGS frame ack:1");
> +
> +        len = 0;
> +
> +    } else {
> +        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, h2c->connection->log, 0,
> +                       "http2 send SETTINGS frame params:3");
> +
> +        len = NGX_HTTP_V2_SETTINGS_PARAM_SIZE * 3;
> +    }
>  
>      frame = ngx_palloc(h2c->pool, sizeof(ngx_http_v2_out_frame_t));
>      if (frame == NULL) {
> @@ -2462,8 +2491,6 @@ ngx_http_v2_send_settings(ngx_http_v2_co
>          return NGX_ERROR;
>      }
>  
> -    len = ack ? 0 : (sizeof(uint16_t) + sizeof(uint32_t)) * 3;
> -
>      buf = ngx_create_temp_buf(h2c->pool, NGX_HTTP_V2_FRAME_HEADER_SIZE + len);
>      if (buf == NULL) {
>          return NGX_ERROR;
> @@ -2494,15 +2521,27 @@ ngx_http_v2_send_settings(ngx_http_v2_co
>          h2scf = ngx_http_get_module_srv_conf(h2c->http_connection->conf_ctx,
>                                               ngx_http_v2_module);
>  
> +        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, h2c->connection->log, 0,
> +                       "http2 send SETTINGS frame MAX_CONCURRENT_STREAMS:%ui",
> +                       h2scf->concurrent_streams);
> +
>          buf->last = ngx_http_v2_write_uint16(buf->last,
>                                               NGX_HTTP_V2_MAX_STREAMS_SETTING);
>          buf->last = ngx_http_v2_write_uint32(buf->last,
>                                               h2scf->concurrent_streams);
>  
> +        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, h2c->connection->log, 0,
> +                       "http2 send SETTINGS frame INITIAL_WINDOW_SIZE:%uz",
> +                       h2scf->preread_size);
> +
>          buf->last = ngx_http_v2_write_uint16(buf->last,
>                                           NGX_HTTP_V2_INIT_WINDOW_SIZE_SETTING);
>          buf->last = ngx_http_v2_write_uint32(buf->last, h2scf->preread_size);
>  
> +        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, h2c->connection->log, 0,
> +                       "http2 send SETTINGS frame MAX_FRAME_SIZE:%ud",
> +                       NGX_HTTP_V2_MAX_FRAME_SIZE);
> +
>          buf->last = ngx_http_v2_write_uint16(buf->last,
>                                             NGX_HTTP_V2_MAX_FRAME_SIZE_SETTING);
>          buf->last = ngx_http_v2_write_uint32(buf->last,

You can always find these values in configuration, and I can't remember a case where
I've ever needed them.  On the contrary, there's always a problem with the huge size
of typical http/2 debug log.  So it's not a good idea to add something just because
we can.

  wbr, Valentin V. Bartenev