[FFmpeg-devel] [PATCH 2/2] avformat/tls_schannel: immediately return decrypted data if available

[Hendrik Leppkes]

On Wed, May 13, 2020 at 12:12 AM Jan Ekström <jeebjp at gmail.com> wrote:
>
> Until now, we would have only attempted to utilize already decrypted
> data if it was enough to fill the size of buffer requested, that could
> very well be up to 32 kilobytes.
>
> With keep-alive connections this would just lead to recv blocking
> until rw_timeout had been reached, as the connection would not be
> officially closed after each transfer. This would also lead to a
> loop, as such timed out I/O request would just be attempted again.
>
> By just returning teh available decrypted data, keep-alive based
> connectivity such as HLS playback is fixed with schannel.
> ---
>  libavformat/tls_schannel.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/libavformat/tls_schannel.c b/libavformat/tls_schannel.c
> index 7a8842e7fe..4a1c5901d0 100644
> --- a/libavformat/tls_schannel.c
> +++ b/libavformat/tls_schannel.c
> @@ -392,7 +392,12 @@ static int tls_read(URLContext *h, uint8_t *buf, int len)
>      int size, ret;
>      int min_enc_buf_size = len + SCHANNEL_FREE_BUFFER_SIZE;
>
> -    if (len <= c->dec_buf_offset)
> +    if (c->dec_buf_offset > 0)
> +        /* If we have some left-over data from previous network activity,
> +         * return it first in case it is enough. It may contain
> +         * data that is required to know whether this connection
> +         * is still required or not, esp. in case of HTTP keep-alive
> +         * connections. */
>          goto cleanup;
>

Can you move the comment above the if(..)?
I feel like if blocks with no braces should have the single statement
follow immediately, with no breaks from comments or otherwise, just to
make sure its very clear that it belongs together.

Change otherwise LGTM.

-  Hendrik