[FFmpeg-devel] [PATCH v4] avformat/http, icecast, rtsp: Add option to disable send-100-continue

Jun Li junli1026 at gmail.com
Mon Mar 25 23:42:01 EET 2019


On Fri, Mar 22, 2019 at 4:12 PM Jun Li <junli1026 at gmail.com> wrote:

> The current setting for send-100-continue option is either
> enabled if applicable or forced enabled, no option to force
> disable the header. This change is to expand the option setting
> to provide more flexibility, which is useful for rstp case.
> ---
>  libavformat/http.c    | 28 +++++++++++++++++-----------
>  libavformat/icecast.c |  2 +-
>  libavformat/rtsp.c    |  1 +
>  3 files changed, 19 insertions(+), 12 deletions(-)
>
> diff --git a/libavformat/http.c b/libavformat/http.c
> index 74d743850d..5a937994cf 100644
> --- a/libavformat/http.c
> +++ b/libavformat/http.c
> @@ -113,6 +113,7 @@ typedef struct HTTPContext {
>      uint8_t *inflate_buffer;
>  #endif /* CONFIG_ZLIB */
>      AVDictionary *chained_options;
> +    /* -1 = try to send if applicable, 0 = always disabled, 1 = always
> enabled */
>      int send_expect_100;
>      char *method;
>      int reconnect;
> @@ -155,7 +156,7 @@ static const AVOption options[] = {
>      { "auth_type", "HTTP authentication type",
> OFFSET(auth_state.auth_type), AV_OPT_TYPE_INT, { .i64 = HTTP_AUTH_NONE },
> HTTP_AUTH_NONE, HTTP_AUTH_BASIC, D | E, "auth_type"},
>      { "none", "No auth method set, autodetect", 0, AV_OPT_TYPE_CONST, {
> .i64 = HTTP_AUTH_NONE }, 0, 0, D | E, "auth_type"},
>      { "basic", "HTTP basic authentication", 0, AV_OPT_TYPE_CONST, { .i64
> = HTTP_AUTH_BASIC }, 0, 0, D | E, "auth_type"},
> -    { "send_expect_100", "Force sending an Expect: 100-continue header
> for POST", OFFSET(send_expect_100), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, E
> },
> +    { "send_expect_100", "Force sending an Expect: 100-continue header
> for POST", OFFSET(send_expect_100), AV_OPT_TYPE_BOOL, { .i64 = -1 }, -1, 1,
> E },
>      { "location", "The actual location of the data received",
> OFFSET(location), AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, D | E },
>      { "offset", "initial byte offset", OFFSET(off), AV_OPT_TYPE_INT64, {
> .i64 = 0 }, 0, INT64_MAX, D },
>      { "end_offset", "try to limit the request to bytes preceding this
> offset", OFFSET(end_off), AV_OPT_TYPE_INT64, { .i64 = 0 }, 0, INT64_MAX, D
> },
> @@ -1179,16 +1180,21 @@ static int http_connect(URLContext *h, const char
> *path, const char *local_path,
>                                                  local_path, method);
>      proxyauthstr = ff_http_auth_create_response(&s->proxy_auth_state,
> proxyauth,
>                                                  local_path, method);
> -    if (post && !s->post_data) {
> -        send_expect_100 = s->send_expect_100;
> -        /* The user has supplied authentication but we don't know the
> auth type,
> -         * send Expect: 100-continue to get the 401 response including the
> -         * WWW-Authenticate header, or an 100 continue if no auth actually
> -         * is needed. */
> -        if (auth && *auth &&
> -            s->auth_state.auth_type == HTTP_AUTH_NONE &&
> -            s->http_code != 401)
> -            send_expect_100 = 1;
> +
> +     if (post && !s->post_data) {
> +        if (s->send_expect_100 != -1) {
> +            send_expect_100 = s->send_expect_100;
> +        } else {
> +            send_expect_100 = 0;
> +            /* The user has supplied authentication but we don't know the
> auth type,
> +             * send Expect: 100-continue to get the 401 response
> including the
> +             * WWW-Authenticate header, or an 100 continue if no auth
> actually
> +             * is needed. */
> +            if (auth && *auth &&
> +                s->auth_state.auth_type == HTTP_AUTH_NONE &&
> +                s->http_code != 401)
> +                send_expect_100 = 1;
> +        }
>      }
>
>  #if FF_API_HTTP_USER_AGENT
> diff --git a/libavformat/icecast.c b/libavformat/icecast.c
> index c93b06b553..d2198b78ec 100644
> --- a/libavformat/icecast.c
> +++ b/libavformat/icecast.c
> @@ -115,7 +115,7 @@ static int icecast_open(URLContext *h, const char
> *uri, int flags)
>      av_dict_set(&opt_dict, "auth_type", "basic", 0);
>      av_dict_set(&opt_dict, "headers", headers, 0);
>      av_dict_set(&opt_dict, "chunked_post", "0", 0);
> -    av_dict_set(&opt_dict, "send_expect_100", s->legacy_icecast ? "0" :
> "1", 0);
> +    av_dict_set(&opt_dict, "send_expect_100", s->legacy_icecast ? "-1" :
> "1", 0);
>      if (NOT_EMPTY(s->content_type))
>          av_dict_set(&opt_dict, "content_type", s->content_type, 0);
>      else
> diff --git a/libavformat/rtsp.c b/libavformat/rtsp.c
> index ae8811234a..6e67e411b9 100644
> --- a/libavformat/rtsp.c
> +++ b/libavformat/rtsp.c
> @@ -1793,6 +1793,7 @@ redirect:
>                   sessioncookie);
>          av_opt_set(rt->rtsp_hd_out->priv_data, "headers", headers, 0);
>          av_opt_set(rt->rtsp_hd_out->priv_data, "chunked_post", "0", 0);
> +        av_opt_set(rt->rtsp_hd_out->priv_data, "send_expect_100", "0", 0);
>
>          /* Initialize the authentication state for the POST session. The
> HTTP
>           * protocol implementation doesn't properly handle multi-pass
> --
> 2.17.1
>


Ping.
The current setting for send_100_expect in http.c is applicable only when
request is POST
and post body is empty. The code checks the post body as this:
* +     if (post && !s->post_data) { *
    ......

This is absolutely correct. But rtsp tunnel in http is a special case. It
post the http header
without any post_data, and then write the tunneled data into the tcp file
descriptor --  that is
two steps and skips the s->post_data.

So in the case, it exactly falls into the send_100_expect condition
although the real post data
will be written to fd later. It is also an issue when I test it with IP
cameras because they don't
support "Expect: 100-continue".

I don't see a smart fix in http.c because whoever use http.c can skip the
http API and write
to the TCP fd directly. This kind of behavior will create a a valid post
operation but http.c
would never get any information of post_data. It kind of skips the http
layer and directly talk
to the tcp.

So the patch here I proposed another path --- trust the user who is using
http.c. In this specific
case, it is rtsp.c who is using http.c, so it is rtsp's obligation to
configure the correct header since
it choose to skip http and write post data directly to the file descriptor.

This is how this patch comes out.

Thanks
-Jun


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