[vlc-devel] [PATCH 6/7] mdns: Add basic ip address detection (Linux)

[Alexandre Janniaux]

Hi,

This can't work at all, on archlinux, debian, fedora, etc, it's not ethxx
anymore since a long time and can't be guessed like that.

You would have better heuristic with using the ip associated for the default
route, but you might even want to choose the interface(s?) on which you're
exposing the services.

Greats,

--
Alexandre Janniaux
VideoLabs

On Wed, Jul 24, 2019 at 10:43:49PM +0700, Roland Bewick wrote:
> ---
>  modules/services_discovery/microdns.c | 62 +++++++++++++++++++++++++++++++++--
>  1 file changed, 59 insertions(+), 3 deletions(-)
>
> diff --git a/modules/services_discovery/microdns.c b/modules/services_discovery/microdns.c
> index c460126b58..fa34ffa8d8 100644
> --- a/modules/services_discovery/microdns.c
> +++ b/modules/services_discovery/microdns.c
> @@ -28,6 +28,12 @@
>  #include <stdatomic.h>
>  #include <assert.h>
>
> +#if defined( _WIN32 )
> +
> +#else
> +    #include <ifaddrs.h>
> +#endif
> +
>  #include <vlc_common.h>
>  #include <vlc_plugin.h>
>  #include <vlc_modules.h>
> @@ -868,9 +874,59 @@ CloseRD( vlc_object_t *p_this )
>      CleanDiscoveryCommon( p_sys );
>  }
>
> -static char * detect_ip_address()
> +static char * detect_ip_address( vlc_object_t *p_obj )
>  {
> -    return strdup("127.0.0.1"); /* TODO: actually detect ip address */
> +    char result[16] = "127.0.0.1";
> +    bool found = false;
> +#if defined( _WIN32 )
> +
> +#else
> +    struct ifaddrs *id;
> +    if( getifaddrs( &id ) == 0 )
> +    {
> +        int selected_priority = 0;
> +
> +        for( ; id != NULL; id = id->ifa_next )
> +        {
> +            if( id->ifa_addr->sa_family == AF_INET )
> +            {
> +                struct sockaddr_in *addr_in = (struct sockaddr_in *)id->ifa_addr;
> +
> +                char *ip_address = inet_ntoa( addr_in->sin_addr );
> +
> +                /* TODO: smarter priority function. */
> +                int priority = 0;
> +                if( strncmp( "eth0", id->ifa_name, strlen( "eth0" ) ) == 0 )
> +                {
> +                    priority = 1000;
> +                }
> +                else if( strncmp( "wifi0", id->ifa_name, strlen( "wifi0" ) ) == 0 )
> +                {
> +                    priority = 2000;
> +                }
> +
> +                msg_Dbg( p_obj, "Assigned interface %s priority %d",
> +                         id->ifa_name, priority);
> +
> +                if( priority > selected_priority )
> +                {
> +                    strcpy( result, ip_address );
> +                    selected_priority = priority;
> +                    found = true;
> +                }
> +            }
> +        }
> +    }
> +    else
> +    {
> +        msg_Err( p_obj, "Couldn't get interface addresses");
> +    }
> +#endif
> +
> +    if ( !found )
> +        msg_Err( p_obj, "No interface address found");
> +
> +    return strdup(result);
>  }
>
>  static int
> @@ -901,7 +957,7 @@ OpenSA( vlc_object_t *p_obj )
>      if( !p_sys->psz_http_host )
>      {
>          msg_Dbg( p_obj, "http-host unset, detecting local IP address...");
> -        p_sys->psz_http_host = detect_ip_address();
> +        p_sys->psz_http_host = detect_ip_address( p_obj );
>          msg_Dbg( p_obj, "chose local IP address: %s", p_sys->psz_http_host);
>      }
>
> --
> 2.11.0
>
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