[vlc-devel] [PATCH 3/3] access_output: srt: add support stream encryption

[Hugo Beauzée-Luyssen]

Hi,

On Wed, Nov 15, 2017, at 08:48 AM, Justin Kim wrote:
> For encrypted transmitting, `passphrase` and `key-length`
> properties are added.
> 
> Signed-off-by: Justin Kim <justin.kim at collabora.com>
> ---
>  modules/access_output/srt.c | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/modules/access_output/srt.c b/modules/access_output/srt.c
> index 7de9b9151a..e531e132ff 100644
> --- a/modules/access_output/srt.c
> +++ b/modules/access_output/srt.c
> @@ -47,6 +47,8 @@
>  /* The default latency is 125
>   * which uses srt library internally */
>  #define SRT_DEFAULT_LATENCY 125
> +/* Crypto key length in bytes. */
> +#define SRT_DEFAULT_KEY_LENGTH 16
>  
>  struct sout_access_out_sys_t
>  {
> @@ -56,6 +58,8 @@ struct sout_access_out_sys_t
>      int           i_latency;
>      size_t        i_chunk_size;
>      int           i_event_fd;
> +    char         *psz_passphrase;
> +    int           i_key_length;

Same remark as for the access module, are those required in p_sys ?

>  };
>  
>  static void srt_wait_interrupted(void *p_data)
> @@ -187,6 +191,8 @@ static int Open( vlc_object_t *p_this )
>      p_sys->i_chunk_size = var_InheritInteger( p_access, "chunk-size" );
>      p_sys->i_poll_timeout = var_InheritInteger( p_access, "poll-timeout"
>      );
>      p_sys->i_latency = var_InheritInteger( p_access, "latency" );
> +    p_sys->psz_passphrase = var_InheritString( p_access, "passphrase" );
> +    p_sys->i_key_length = var_InheritInteger( p_access, "key-length" );
>      p_sys->i_poll_id = -1;
>      p_sys->i_event_fd = -1;
>  
> @@ -243,6 +249,14 @@ static int Open( vlc_object_t *p_this )
>      /* Set latency */
>      srt_setsockopt( p_sys->sock, 0, SRTO_TSBPDDELAY, &p_sys->i_latency,
>      sizeof( int ) );
>  
> +    if ( p_sys->psz_passphrase != NULL && p_sys->psz_passphrase[0] !=
> '\0')
> +    {
> +        srt_setsockopt( p_sys->sock, 0, SRTO_PASSPHRASE,
> +            p_sys->psz_passphrase, strlen( p_sys->psz_passphrase ) );
> +        srt_setsockopt( p_sys->sock, 0, SRTO_PBKEYLEN,
> +            &p_sys->i_key_length, sizeof( int ) );
> +    }
> +
>      p_sys->i_poll_id = srt_epoll_create();
>      if ( p_sys->i_poll_id == -1 )
>      {
> @@ -286,6 +300,7 @@ failed:
>          if ( p_sys->i_poll_id != -1 ) srt_epoll_release(
>          p_sys->i_poll_id );
>          if ( p_sys->sock != -1 ) srt_close( p_sys->sock );
>          if ( p_sys->i_event_fd != -1 ) close( p_sys->i_event_fd );
> +        if ( p_sys->psz_passphrase != NULL) free
> (p_sys->psz_passphrase);
>  
>          free( p_sys );
>      }
> @@ -307,6 +322,11 @@ static void Close( vlc_object_t * p_this )
>          p_sys->i_event_fd = -1;
>      }
>  
> +    if ( p_sys->psz_passphrase != NULL)

Same remark about NULL check before freeing. free(NULL) is totally OK.

> +    {
> +        free (p_sys->psz_passphrase);
> +    }
> +
>      free( p_sys );
>  }
>  
> @@ -322,6 +342,9 @@ vlc_module_begin()
>      add_integer( "poll-timeout", SRT_DEFAULT_POLL_TIMEOUT,
>              N_("Return poll wait after timeout miliseconds (-1 =
>              infinite)"), NULL, true )
>      add_integer( "latency", SRT_DEFAULT_LATENCY, N_("SRT latency (ms)"),
>      NULL, true )
> +    add_string( "passphrase", "", N_("Password for stream encryption"),
> NULL, false )
> +    add_integer( "key-length", SRT_DEFAULT_KEY_LENGTH,
> +            N_("Crypto key length in bytes [16, 24, 32]"), NULL, false )

Same remark about using change_integer_list

>  
>      set_capability( "sout access", 0 )
>      add_shortcut( "srt" )
> -- 
> 2.15.0
> 

One extra remark, this will store the passphrase in plain text in VLC's
config file, I'm not sure that's a desirable behavior. It would probably
better to use the dialog API and let it store the result in a keystore.

Regards,

-- 
  Hugo Beauzée-Luyssen
  hugo at beauzee.fr