[PATCH] HTTP/2: make http2 server support http1

[Valentin V. Bartenev]

On Monday 05 March 2018 11:11:08 Haitao Lv wrote:
[..]
> > @@ -145,10 +152,6 @@ ngx_http_parse_request_line(ngx_http_request_t *r, ngx_buf_t *b)
> >         case sw_start:
> >             r->request_start = p;
> > 
> > -            if (ch == CR || ch == LF) {
> > -                break;
> > -            }
> > -
> 
> I think Nginx should not allow any leading \r or \n. HTTP client should never send this chars
> before the request line. Support this feature makes the buffer management more harder.

Support for this feature is required.  See the notes from Ruslan.
Some clients send additional empty line between keepalive requests.


[..]
> > +#if (NGX_HTTP_V2)
> > +        case sw_h2_preface:
> > +
> > +            if (ch == *n++) {
> 
> I introduce a new sw_h2_preface state. In this state, the parser will check the h2 preface char by char.
> 
> The parser only check at most 20 chars "* HTTP/2.0\r\n\r\nSM\r\n\r\n". So the buffer will not be fulfilled.
> 

The recv() operation gets buffer size as an argument.

Thus, the buffer can be fully filled with all the data copied from
a socket buffer.  HTTP/2 clients usually don't send preface alone.
They can send other data with the preface. 


[..]
> > +#if (NGX_HTTP_V2)
> > +static void
> > +ngx_http_process_h2_preface(ngx_event_t *rev)
> > +{
> > +    size_t                      len;
> > +    ngx_connection_t           *c;
> > +    ngx_http_request_t         *r;
> > +    ngx_http_connection_t      *hc;
> > +    ngx_http_v2_main_conf_t    *h2mcf;
> > +
> > +    c = rev->data;
> > +    r = c->data;
> > +    hc = r->http_connection;
> > +
> > +    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
> > +            "http process h2 preface");
> > +
> > +    r->header_in->pos = r->header_in->start + 24;
> > +
> > +    len = r->header_in->last - r->header_in->pos;
> > +
> > +    h2mcf = ngx_http_get_module_main_conf(hc->conf_ctx, ngx_http_v2_module);
> > +
> > +    if (len <= h2mcf->recv_buffer_size) {
> 
> We check the recv buffer size before do the ngx_http_v2_init_after_preface.
> 
[..]

See above.  It's a bad idea to decline request with a "client sent
invalid h2 preface" message in error log just because client has
sent more HTTP/2 frames right after the preface.

Overall, the patch looks like a hack and introduces too much
complexity for this feature.  While I understand the reasoning,
the proposed implementation cannot be accepted.

Protocol detection before starting processing HTTP/1 or HTTP/2
could be a better way to go.

  wbr, Valentin V. Bartenev