[FFmpeg-devel] [PATCH 1/1] avformat/http: flushing tcp receive buffer when it is write only mode

[Steven Liu]

> On 28 Mar 2018, at 12:52, vdixit at akamai.com wrote:
> 
> From: Vishwanath Dixit <vdixit at akamai.com>
> 
> In write only mode, the TCP receive buffer keeps growing and eventually
> becomes full. This results in zero tcp window size, which in turn causes
> unwanted issues, like, terminated tcp connection. The issue is apparent
> when http persistent connection is enabled in hls/dash streaming use
> cases. To overcome this issue, the logic here reads and discards the data
> from the tcp socket.
> ---
> libavformat/http.c | 7 +++++++
> 1 file changed, 7 insertions(+)
> 
> diff --git a/libavformat/http.c b/libavformat/http.c
> index 983034f..e6d414b 100644
> --- a/libavformat/http.c
> +++ b/libavformat/http.c
> @@ -1627,6 +1627,13 @@ static int http_shutdown(URLContext *h, int flags)
>         ((flags & AVIO_FLAG_READ) && s->chunked_post && s->listen)) {
>         ret = ffurl_write(s->hd, footer, sizeof(footer) - 1);
>         ret = ret > 0 ? 0 : ret;
> +        /* flush the receive buffer when it is write only mode */
> +        if (!(flags & AVIO_FLAG_READ)) {
> +            char buf[1024];
> +            s->hd->flags |= AVIO_FLAG_NONBLOCK;
> +            ffurl_read(s->hd, buf, sizeof(buf));
ffurl_read have a int return value.

407 int ffurl_read(URLContext *h, unsigned char *buf, int size)
408 {
409     if (!(h->flags & AVIO_FLAG_READ))
410         return AVERROR(EIO);
411     return retry_transfer_wrapper(h, buf, size, 1, h->prot->url_read);
412 }


> +            s->hd->flags &= ~AVIO_FLAG_NONBLOCK;
> +        }
>         s->end_chunked_post = 1;
>     }
> 
> -- 
> 1.9.1
> 
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Thanks
Steven