threadshare: udp: add multicast-iface property

similar to the non threadshare counterparts, the ts-udpsink can accept
only one multicast interface and the ts-udpsrc can accept a list of
interfaces to be listening on for the multicast.

Use the getifaddrs crate to get the available network interfaces and filter
the desired interfaces from the available interfaces

Reuse a custom api written for PTP helper to join and leave multicast group
for IPv4 based addresses. Continue to use the UdpSocket crate's _multicast_v6
to join/leave an IPv6 multicast group

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1420>

Cargo.lock

@@ -2203,6 +2203,17 @@ dependencies = [
  "version_check",
 ]
 
+[[package]]
+name = "getifaddrs"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5145f1db081f9c1bd68384b4602d701efbd1b1fb8fa1a4938bd8eebfaa34ea76"
+dependencies = [
+ "bitflags 2.6.0",
+ "libc",
+ "windows-sys 0.59.0",
+]
+
 [[package]]
 name = "getrandom"
 version = "0.2.15"
@@ -3066,6 +3077,7 @@ dependencies = [
  "concurrent-queue",
  "flume",
  "futures",
+ "getifaddrs",
  "gio",
  "gst-plugin-version-helper",
  "gstreamer",
@@ -3074,6 +3086,7 @@ dependencies = [
  "gstreamer-check",
  "gstreamer-net",
  "gstreamer-rtp",
+ "libc",
  "pin-project-lite",
  "pkg-config",
  "polling",
@@ -3083,6 +3096,7 @@ dependencies = [
  "socket2",
  "waker-fn",
  "winapi",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]

docs/plugins/gst_plugins_cache.json

@@ -14220,6 +14220,18 @@
                         "type": "gboolean",
                         "writable": true
                     },
+                    "multicast-iface": {
+                        "blurb": "The network interface on which to join the multicast group. (Supports only single interface)",
+                        "conditionally-available": false,
+                        "construct": false,
+                        "construct-only": false,
+                        "controllable": false,
+                        "default": "NULL",
+                        "mutable": "null",
+                        "readable": true,
+                        "type": "gchararray",
+                        "writable": true
+                    },
                     "qos-dscp": {
                         "blurb": "Quality of Service, differentiated services code point (-1 default)",
                         "conditionally-available": false,
@@ -14468,6 +14480,18 @@
                         "type": "guint",
                         "writable": true
                     },
+                    "multicast-iface": {
+                        "blurb": "The network interface on which to join the multicast group. This allows multiple interfaces\n                        separated by comma. (\"eth0,eth1\")",
+                        "conditionally-available": false,
+                        "construct": false,
+                        "construct-only": false,
+                        "controllable": false,
+                        "default": "NULL",
+                        "mutable": "null",
+                        "readable": true,
+                        "type": "gchararray",
+                        "writable": true
+                    },
                     "port": {
                         "blurb": "Port to listen on",
                         "conditionally-available": false,

generic/threadshare/Cargo.toml

@@ -26,6 +26,9 @@ rustix = { version = "0.38.2", default-features = false, features = ["std", "fs"
 slab = "0.4.7"
 socket2 = {features = ["all"], version = "0.5"}
 waker-fn = "1.1"
+getifaddrs = "0.1"
+libc = "0.2"
+windows-sys = "0.59.0"
 
 # Used by examples
 clap = { version = "4", features = ["derive"], optional = true }

generic/threadshare/src/lib.rs

@@ -28,6 +28,8 @@ mod tcpclientsrc;
 mod udpsink;
 mod udpsrc;
 
+pub mod net;
+
 use gst::glib;
 
 fn plugin_init(plugin: &gst::Plugin) -> Result<(), glib::BoolError> {

generic/threadshare/src/net.rs

@@ -0,0 +1,371 @@
+// GStreamer
+//
+// Copyright (C) 2015-2023 Sebastian Dröge <sebastian@centricular.com>
+//
+// This Source Code Form is subject to the terms of the Mozilla Public License, v2.0.
+// If a copy of the MPL was not distributed with this file, You can obtain one at
+// <https://mozilla.org/MPL/2.0/>.
+//
+// SPDX-License-Identifier: MPL-2.0
+
+use getifaddrs::Interface;
+
+#[cfg(unix)]
+pub mod imp {
+    use super::*;
+
+    use std::{io, mem, net::UdpSocket, os::unix::io::AsRawFd};
+
+    use libc::{
+        in_addr, ip_mreqn, setsockopt, IPPROTO_IP, IP_ADD_MEMBERSHIP, IP_DROP_MEMBERSHIP,
+        IP_MULTICAST_IF,
+    };
+
+    #[cfg(target_os = "macos")]
+    use libc::ip_mreq;
+
+    #[cfg(any(target_os = "solaris", target_os = "illumos", target_os = "macos"))]
+    use std::net::IpAddr;
+    use std::net::Ipv4Addr;
+
+    /// Join multicast address for a given interface.
+    pub fn join_multicast_v4(
+        socket: &UdpSocket,
+        addr: &Ipv4Addr,
+        iface: &Interface,
+    ) -> Result<(), io::Error> {
+        multicast_group_operation_v4(socket, addr, iface, true)
+    }
+
+    /// Leave multicast address for a given interface.
+    pub fn leave_multicast_v4(
+        socket: &UdpSocket,
+        addr: &Ipv4Addr,
+        iface: &Interface,
+    ) -> Result<(), io::Error> {
+        multicast_group_operation_v4(socket, addr, iface, false)
+    }
+
+    fn multicast_group_operation_v4(
+        socket: &UdpSocket,
+        addr: &Ipv4Addr,
+        iface: &Interface,
+        join: bool,
+    ) -> Result<(), io::Error> {
+        let index = iface.index.unwrap_or(0);
+
+        #[cfg(not(any(target_os = "solaris", target_os = "illumos", target_os = "macos")))]
+        {
+            let group_op: i32 = if join {
+                IP_ADD_MEMBERSHIP
+            } else {
+                IP_DROP_MEMBERSHIP
+            };
+
+            let mreqn = ip_mreqn {
+                imr_multiaddr: in_addr {
+                    s_addr: u32::from_ne_bytes(addr.octets()),
+                },
+                imr_address: in_addr {
+                    s_addr: u32::from_ne_bytes(Ipv4Addr::UNSPECIFIED.octets()),
+                },
+                imr_ifindex: index as _,
+            };
+
+            // SAFETY: Requires a valid ip_mreq or ip_mreqn struct to be passed together
+            // with its size for checking which of the two it is. On errors a negative
+            // integer is returned.
+            unsafe {
+                if setsockopt(
+                    socket.as_raw_fd(),
+                    IPPROTO_IP,
+                    group_op,
+                    &mreqn as *const _ as *const _,
+                    mem::size_of_val(&mreqn) as _,
+                ) < 0
+                {
+                    return Err(io::Error::last_os_error());
+                }
+            }
+
+            #[cfg(not(any(target_os = "openbsd", target_os = "dragonfly", target_os = "netbsd")))]
+            {
+                let mreqn = ip_mreqn {
+                    imr_multiaddr: in_addr {
+                        s_addr: u32::from_ne_bytes(Ipv4Addr::UNSPECIFIED.octets()),
+                    },
+                    imr_address: in_addr {
+                        s_addr: u32::from_ne_bytes(Ipv4Addr::UNSPECIFIED.octets()),
+                    },
+                    imr_ifindex: index as _,
+                };
+
+                // SAFETY: Requires a valid ip_mreq or ip_mreqn struct to be passed together
+                // with its size for checking which of the two it is. On errors a negative
+                // integer is returned.
+                unsafe {
+                    if setsockopt(
+                        socket.as_raw_fd(),
+                        IPPROTO_IP,
+                        IP_MULTICAST_IF,
+                        &mreqn as *const _ as *const _,
+                        mem::size_of_val(&mreqn) as _,
+                    ) < 0
+                    {
+                        return Err(io::Error::last_os_error());
+                    }
+                }
+            }
+            #[cfg(any(target_os = "openbsd", target_os = "dragonfly"))]
+            {
+                let addr = in_addr {
+                    s_addr: u32::from_ne_bytes(ip_addr.octets()),
+                };
+
+                // SAFETY: Requires a valid in_addr struct to be passed together with its size for
+                // checking which of the two it is. On errors a negative integer is returned.
+                unsafe {
+                    if setsockopt(
+                        socket.as_raw_fd(),
+                        IPPROTO_IP,
+                        IP_MULTICAST_IF,
+                        &addr as *const _ as *const _,
+                        mem::size_of_val(&addr) as _,
+                    ) < 0
+                    {
+                        return Err(io::Error::last_os_error());
+                    }
+                }
+            }
+            #[cfg(target_os = "netbsd")]
+            {
+                let idx = (index as u32).to_be();
+
+                // SAFETY: Requires a valid in_addr struct or interface index in network byte order
+                // to be passed together with its size for checking which of the two it is. On
+                // errors a negative integer is returned.
+                unsafe {
+                    if setsockopt(
+                        socket.as_raw_fd(),
+                        IPPROTO_IP,
+                        IP_MULTICAST_IF,
+                        &idx as *const _ as *const _,
+                        mem::size_of_val(&idx) as _,
+                    ) < 0
+                    {
+                        return Err(io::Error::last_os_error());
+                    }
+                }
+            }
+
+            Ok(())
+        }
+
+        #[cfg(any(target_os = "solaris", target_os = "illumos"))]
+        {
+            let ip_addr = match iface.address {
+                IpAddr::V4(ipv4_addr) => ipv4_addr,
+                IpAddr::V6(_) => return Err(io::Error::other("Interface address is IPv6")),
+            };
+
+            if join {
+                socket.join_multicast_v4(addr, &ip_addr).with_context(|| {
+                    format!(
+                        "Failed joining multicast group for interface {} at address {}",
+                        iface.name, ip_addr
+                    )
+                })?;
+            } else {
+                socket.leave_multicast_v4(addr, &ip_addr).with_context(|| {
+                    format!(
+                        "Failed leave multicast group for interface {} at address {}",
+                        iface.name, ip_addr
+                    )
+                })?;
+            }
+
+            // SAFETY: Requires a valid in_addr struct to be passed together with its size for
+            // checking which of the two it is. On errors a negative integer is returned.
+            unsafe {
+                if setsockopt(
+                    socket.as_raw_fd(),
+                    IPPROTO_IP,
+                    IP_MULTICAST_IF,
+                    &addr as *const _ as *const _,
+                    mem::size_of_val(&addr) as _,
+                ) < 0
+                {
+                    return Err(io::Error::last_os_error());
+                }
+            }
+
+            Ok(())
+        }
+
+        #[cfg(target_os = "macos")]
+        {
+            let ip_addr = match iface.address {
+                IpAddr::V4(ipv4_addr) => ipv4_addr,
+                IpAddr::V6(_) => return Err(io::Error::other("Interface address is IPv6")),
+            };
+
+            let mreq = ip_mreq {
+                imr_multiaddr: in_addr {
+                    s_addr: u32::from_ne_bytes(addr.octets()),
+                },
+                imr_address: in_addr {
+                    s_addr: u32::from_ne_bytes(ip_addr.octets()),
+                },
+            };
+
+            let mreqn = ip_mreqn {
+                imr_multiaddr: in_addr {
+                    s_addr: u32::from_ne_bytes(Ipv4Addr::UNSPECIFIED.octets()),
+                },
+                imr_address: in_addr {
+                    s_addr: u32::from_ne_bytes(Ipv4Addr::UNSPECIFIED.octets()),
+                },
+                imr_ifindex: index as _,
+            };
+
+            let group_op: i32 = if join {
+                IP_ADD_MEMBERSHIP
+            } else {
+                IP_DROP_MEMBERSHIP
+            };
+
+            // SAFETY: Requires a valid ip_mreq struct to be passed together with its size for checking
+            // validity. On errors a negative integer is returned.
+            unsafe {
+                if setsockopt(
+                    socket.as_raw_fd(),
+                    IPPROTO_IP,
+                    group_op,
+                    &mreq as *const _ as *const _,
+                    mem::size_of_val(&mreq) as _,
+                ) < 0
+                {
+                    return Err(io::Error::last_os_error());
+                }
+            }
+
+            // SAFETY: Requires a valid ip_mreqn struct to be passed together
+            // with its size for checking which of the two it is. On errors a negative
+            // integer is returned.
+            unsafe {
+                if setsockopt(
+                    socket.as_raw_fd(),
+                    IPPROTO_IP,
+                    IP_MULTICAST_IF,
+                    &mreqn as *const _ as *const _,
+                    mem::size_of_val(&mreqn) as _,
+                ) < 0
+                {
+                    return Err(io::Error::last_os_error());
+                }
+            }
+
+            Ok(())
+        }
+    }
+}
+
+#[cfg(windows)]
+pub mod imp {
+    use super::*;
+
+    use std::{
+        io, mem,
+        net::{Ipv4Addr, UdpSocket},
+        os::windows::io::AsRawSocket,
+    };
+
+    use windows_sys::Win32::Networking::WinSock::{
+        setsockopt, WSAGetLastError, IN_ADDR, IN_ADDR_0, IPPROTO_IP, IP_ADD_MEMBERSHIP,
+        IP_DROP_MEMBERSHIP, IP_MREQ, IP_MULTICAST_IF,
+    };
+
+    /// Join multicast address for a given interface.
+    pub fn join_multicast_v4(
+        socket: &UdpSocket,
+        addr: &Ipv4Addr,
+        iface: &Interface,
+    ) -> Result<(), io::Error> {
+        multicast_group_operation_v4(socket, addr, iface, IP_ADD_MEMBERSHIP)
+        // let ip_addr = Ipv4Addr::new(0, 0, 0, iface.index.unwrap() as u8);
+        // socket.join_multicast_v4(addr, &ip_addr).unwrap();
+        // return Ok(());
+    }
+
+    /// Leave multicast address for a given interface.
+    pub fn leave_multicast_v4(
+        socket: &UdpSocket,
+        addr: &Ipv4Addr,
+        iface: &Interface,
+    ) -> Result<(), io::Error> {
+        multicast_group_operation_v4(socket, addr, iface, IP_DROP_MEMBERSHIP)
+        // let ip_addr = Ipv4Addr::new(0, 0, 0, iface.index.unwrap() as u8);
+        // socket.leave_multicast_v4(addr, &ip_addr).unwrap();
+        // return Ok(());
+    }
+
+    fn multicast_group_operation_v4(
+        socket: &UdpSocket,
+        addr: &Ipv4Addr,
+        iface: &Interface,
+        group_op: i32,
+    ) -> Result<(), io::Error> {
+        let index = iface.index.unwrap_or(0);
+
+        let mreq = IP_MREQ {
+            imr_multiaddr: IN_ADDR {
+                S_un: IN_ADDR_0 {
+                    S_addr: u32::from_ne_bytes(addr.octets()),
+                },
+            },
+            imr_interface: IN_ADDR {
+                S_un: IN_ADDR_0 {
+                    S_addr: u32::from_ne_bytes(Ipv4Addr::new(0, 0, 0, index as u8).octets()),
+                },
+            },
+        };
+
+        // SAFETY: Requires a valid ip_mreq struct to be passed together with its size for checking
+        // validity. On errors a negative integer is returned.
+        unsafe {
+            if setsockopt(
+                socket.as_raw_socket() as usize,
+                IPPROTO_IP,
+                group_op,
+                &mreq as *const _ as *const _,
+                mem::size_of_val(&mreq) as _,
+            ) < 0
+            {
+                return Err(io::Error::from_raw_os_error(WSAGetLastError()));
+            }
+        }
+
+        let ip_addr = IN_ADDR {
+            S_un: IN_ADDR_0 {
+                S_addr: u32::from_ne_bytes(Ipv4Addr::new(0, 0, 0, index as u8).octets()),
+            },
+        };
+
+        // SAFETY: Requires a valid IN_ADDR struct to be passed together with its size for checking
+        // which of the two it is. On errors a negative integer is returned.
+        unsafe {
+            if setsockopt(
+                socket.as_raw_socket() as usize,
+                IPPROTO_IP,
+                IP_MULTICAST_IF,
+                &ip_addr as *const _ as *const _,
+                mem::size_of_val(&ip_addr) as _,
+            ) < 0
+            {
+                return Err(io::Error::last_os_error());
+            }
+        }
+
+        Ok(())
+    }
+}

generic/threadshare/src/socket.rs

@@ -99,6 +99,10 @@ impl<T: SocketRead> Socket<T> {
         self.clock = clock;
         self.base_time = base_time;
     }
+
+    pub fn get(&self) -> &T {
+        &self.reader
+    }
 }
 
 #[derive(Debug)]

generic/threadshare/src/udpsink/imp.rs

@@ -28,13 +28,14 @@ use gst::{element_error, error_msg};
 
 use std::sync::LazyLock;
 
+use crate::net;
 use crate::runtime::executor::block_on_or_add_sub_task;
 use crate::runtime::prelude::*;
 use crate::runtime::{self, Async, Context, PadSink};
 use crate::socket::{wrap_socket, GioSocketWrapper};
 
 use std::collections::BTreeSet;
-use std::net::{IpAddr, Ipv4Addr, SocketAddr, UdpSocket};
+use std::net::{IpAddr, SocketAddr, UdpSocket};
 use std::sync::{Arc, Mutex};
 use std::time::Duration;
 
@@ -57,6 +58,7 @@ const DEFAULT_QOS_DSCP: i32 = -1;
 const DEFAULT_CLIENTS: &str = "";
 const DEFAULT_CONTEXT: &str = "";
 const DEFAULT_CONTEXT_WAIT: Duration = Duration::ZERO;
+const DEFAULT_MULTICAST_IFACE: Option<&str> = None;
 
 #[derive(Debug, Clone, Copy)]
 struct SocketConf {
@@ -92,6 +94,7 @@ struct Settings {
     qos_dscp: i32,
     context: String,
     context_wait: Duration,
+    multicast_iface: Option<String>,
 }
 
 impl Default for Settings {
@@ -110,6 +113,7 @@ impl Default for Settings {
             qos_dscp: DEFAULT_QOS_DSCP,
             context: DEFAULT_CONTEXT.into(),
             context_wait: DEFAULT_CONTEXT_WAIT,
+            multicast_iface: DEFAULT_MULTICAST_IFACE.map(Into::into),
         }
     }
 }
@@ -128,7 +132,7 @@ struct UdpSinkPadHandler(Arc<futures::lock::Mutex<UdpSinkPadHandlerInner>>);
 impl UdpSinkPadHandler {
     fn prepare(
         &self,
-        _imp: &UdpSink,
+        imp: &UdpSink,
         socket: Option<Async<UdpSocket>>,
         socket_v6: Option<Async<UdpSocket>>,
         settings: &Settings,
@@ -141,6 +145,58 @@ impl UdpSinkPadHandler {
             inner.socket = socket;
             inner.socket_v6 = socket_v6;
 
+            if let Some(multicast_iface) = &settings.multicast_iface {
+                gst::debug!(
+                    CAT,
+                    imp = imp,
+                    "searching for interface: {}",
+                    multicast_iface
+                );
+
+                // The 'InterfaceFilter::name' only checks for the 'name' field , it does not check
+                // whether the given name with the interface 'description' (Friendly Name) on Windows
+
+                // So we first get all the interfaces and then apply filter
+                // for name and description (Friendly Name) of each interface.
+
+                let ifaces = getifaddrs::getifaddrs().map_err(|err| {
+                    gst::error_msg!(
+                        gst::ResourceError::OpenRead,
+                        ["Failed to find interface {}: {}", multicast_iface, err]
+                    )
+                })?;
+
+                let iface_filter = ifaces.filter(|i| {
+                    let ip_ver = if i.address.is_ipv4() { "IPv4" } else { "IPv6" };
+
+                    if &i.name == multicast_iface {
+                        gst::debug!(
+                            CAT,
+                            imp = imp,
+                            "Found interface: {}, version: {ip_ver}",
+                            i.name,
+                        );
+                        true
+                    } else {
+                        #[cfg(windows)]
+                        if &i.description == multicast_iface {
+                            gst::debug!(
+                                CAT,
+                                imp = imp,
+                                "Found interface: {}, version: {ip_ver}",
+                                i.description,
+                            );
+                            return true;
+                        }
+
+                        gst::trace!(CAT, imp = imp, "skipping interface {}", i.name);
+                        false
+                    }
+                });
+
+                inner.multicast_ifaces = iface_filter.collect();
+            }
+
             for addr in inner.clients.iter() {
                 inner.configure_client(addr)?;
             }
@@ -365,6 +421,7 @@ struct UdpSinkPadHandlerInner {
     clients: BTreeSet<SocketAddr>,
     socket_conf: SocketConf,
     segment: Option<gst::Segment>,
+    multicast_ifaces: Vec<getifaddrs::Interface>,
 }
 
 impl Default for UdpSinkPadHandlerInner {
@@ -381,6 +438,7 @@ impl Default for UdpSinkPadHandlerInner {
             )]),
             socket_conf: Default::default(),
             segment: None,
+            multicast_ifaces: Vec::<getifaddrs::Interface>::new(),
         }
     }
 }
@@ -391,22 +449,38 @@ impl UdpSinkPadHandlerInner {
         if client.ip().is_multicast() {
             match client.ip() {
                 IpAddr::V4(addr) => {
-                    if let Some(socket) = self.socket.as_ref() {
+                    let Some(socket) = self.socket.as_ref() else {
+                        return Ok(());
+                    };
+
                     if self.socket_conf.auto_multicast {
-                            socket
+                        for iface in &self.multicast_ifaces {
-                                .as_ref()
+                            if !iface.address.is_ipv4() {
-                                .join_multicast_v4(&addr, &Ipv4Addr::new(0, 0, 0, 0))
+                                gst::debug!(
-                                .map_err(|err| {
+                                    CAT,
+                                    "Skipping the IPv6 version of the interface {}",
+                                    iface.name
+                                );
+                                continue;
+                            }
+
+                            gst::debug!(CAT, "interface {} joining the multicast", iface.name);
+                            net::imp::join_multicast_v4(socket.as_ref(), &addr, iface).map_err(
+                                |err| {
                                     error_msg!(
                                         gst::ResourceError::OpenWrite,
                                         [
-                                            "Failed to join multicast group for {:?}: {}",
+                                            "Failed to join multicast group on iface {} for {:?}: {}",
+                                            iface.name,
                                             client,
                                             err
                                         ]
                                     )
-                                })?;
+                                },
+                            )?;
                         }
+                    }
+
                     if self.socket_conf.multicast_loop {
                         socket.as_ref().set_multicast_loop_v4(true).map_err(|err| {
                             error_msg!(
@@ -426,17 +500,43 @@ impl UdpSinkPadHandlerInner {
                             )
                         })?;
                 }
-                }
                 IpAddr::V6(addr) => {
-                    if let Some(socket) = self.socket_v6.as_ref() {
+                    let Some(socket) = self.socket.as_ref() else {
+                        return Err(error_msg!(
+                            gst::ResourceError::OpenWrite,
+                            ["Socket not available"]
+                        ));
+                    };
+
                     if self.socket_conf.auto_multicast {
-                            socket.as_ref().join_multicast_v6(&addr, 0).map_err(|err| {
+                        for iface in &self.multicast_ifaces {
+                            if !iface.address.is_ipv6() {
+                                gst::debug!(
+                                    CAT,
+                                    "Skipping the IPv4 version of the interface {}",
+                                    iface.name
+                                );
+                                continue;
+                            }
+
+                            gst::debug!(CAT, "interface {} joining the multicast", iface.name);
+                            socket
+                                .as_ref()
+                                .join_multicast_v6(&addr, iface.index.unwrap_or(0))
+                                .map_err(|err| {
                                     error_msg!(
                                         gst::ResourceError::OpenWrite,
-                                    ["Failed to join multicast group for {:?}: {}", client, err]
+                                        [
+                                            "Failed to join multicast group on iface {} for {:?}: {}",
+                                            iface.name,
+                                            client,
+                                            err
+                                        ]
                                     )
                                 })?;
                         }
+                    }
+
                     if self.socket_conf.multicast_loop {
                         socket.as_ref().set_multicast_loop_v6(true).map_err(|err| {
                             error_msg!(
@@ -448,7 +548,6 @@ impl UdpSinkPadHandlerInner {
                     /* FIXME no API for set_multicast_ttl_v6 ? */
                 }
             }
-            }
         } else {
             match client.ip() {
                 IpAddr::V4(_) => {
@@ -487,12 +586,27 @@ impl UdpSinkPadHandlerInner {
         if client.ip().is_multicast() {
             match client.ip() {
                 IpAddr::V4(addr) => {
-                    if let Some(socket) = self.socket.as_ref() {
+                    let Some(socket) = self.socket.as_ref() else {
+                        return Err(error_msg!(
+                            gst::ResourceError::OpenWrite,
+                            ["Socket not available"]
+                        ));
+                    };
+
                     if self.socket_conf.auto_multicast {
-                            socket
+                        for iface in &self.multicast_ifaces {
-                                .as_ref()
+                            if !iface.address.is_ipv4() {
-                                .leave_multicast_v4(&addr, &Ipv4Addr::new(0, 0, 0, 0))
+                                gst::debug!(
-                                .map_err(|err| {
+                                    CAT,
+                                    "Skipping the IPv6 version of the interface {}",
+                                    iface.name
+                                );
+                                continue;
+                            }
+
+                            gst::debug!(CAT, "interface {} leaving the multicast", iface.name);
+                            net::imp::leave_multicast_v4(socket.as_ref(), &addr, iface).map_err(
+                                |err| {
                                     error_msg!(
                                         gst::ResourceError::OpenWrite,
                                         [
@@ -501,16 +615,34 @@ impl UdpSinkPadHandlerInner {
                                             err
                                         ]
                                     )
-                                })?;
+                                },
+                            )?;
                         }
                     }
                 }
                 IpAddr::V6(addr) => {
-                    if let Some(socket) = self.socket_v6.as_ref() {
+                    let Some(socket) = self.socket.as_ref() else {
+                        return Err(error_msg!(
+                            gst::ResourceError::OpenWrite,
+                            ["Socket not available"]
+                        ));
+                    };
+
                     if self.socket_conf.auto_multicast {
+                        for iface in &self.multicast_ifaces {
+                            if !iface.address.is_ipv6() {
+                                gst::debug!(
+                                    CAT,
+                                    "Skipping the IPv4 version of the interface {}",
+                                    iface.name
+                                );
+                                continue;
+                            }
+
+                            gst::debug!(CAT, "interface {} leaving the multicast", iface.name);
                             socket
                                 .as_ref()
-                                .leave_multicast_v6(&addr, 0)
+                                .leave_multicast_v6(&addr, iface.index.unwrap_or(0))
                                 .map_err(|err| {
                                     error_msg!(
                                         gst::ResourceError::OpenWrite,
@@ -952,6 +1084,11 @@ impl ObjectImpl for UdpSink {
                     .blurb("A comma separated list of host:port pairs with destinations")
                     .default_value(Some(DEFAULT_CLIENTS))
                     .build(),
+                glib::ParamSpecString::builder("multicast-iface")
+                    .nick("Multicast Interface")
+                    .blurb("The network interface on which to join the multicast group. (Supports only single interface)")
+                    .default_value(DEFAULT_MULTICAST_IFACE)
+                    .build(),
             ]
         });
 
@@ -1119,6 +1256,9 @@ impl ObjectImpl for UdpSink {
                     value.get::<u32>().expect("type checked upstream").into(),
                 );
             }
+            "multicast-iface" => {
+                settings.multicast_iface = value.get().expect("type checked upstream");
+            }
             _ => unimplemented!(),
         }
     }
@@ -1164,6 +1304,7 @@ impl ObjectImpl for UdpSink {
             }
             "context" => settings.context.to_value(),
             "context-wait" => (settings.context_wait.as_millis() as u32).to_value(),
+            "multicast-iface" => settings.multicast_iface.to_value(),
             _ => unimplemented!(),
         }
     }

generic/threadshare/src/udpsrc/imp.rs

@@ -35,6 +35,7 @@ use std::time::Duration;
 use crate::runtime::prelude::*;
 use crate::runtime::{task, Async, Context, PadSrc, Task, TaskState};
 
+use crate::net;
 use crate::socket::{wrap_socket, GioSocketWrapper, Socket, SocketError, SocketRead};
 use futures::channel::mpsc::{channel, Receiver, Sender};
 use futures::pin_mut;
@@ -51,6 +52,7 @@ const DEFAULT_CONTEXT_WAIT: Duration = Duration::ZERO;
 const DEFAULT_RETRIEVE_SENDER_ADDRESS: bool = true;
 const DEFAULT_MULTICAST_LOOP: bool = true;
 const DEFAULT_BUFFER_SIZE: u32 = 0;
+const DEFAULT_MULTICAST_IFACE: Option<&str> = None;
 
 #[derive(Debug, Default)]
 struct State {
@@ -71,6 +73,7 @@ struct Settings {
     retrieve_sender_address: bool,
     multicast_loop: bool,
     buffer_size: u32,
+    multicast_iface: Option<String>,
 }
 
 impl Default for Settings {
@@ -88,6 +91,7 @@ impl Default for Settings {
             retrieve_sender_address: DEFAULT_RETRIEVE_SENDER_ADDRESS,
             multicast_loop: DEFAULT_MULTICAST_LOOP,
             buffer_size: DEFAULT_BUFFER_SIZE,
+            multicast_iface: DEFAULT_MULTICAST_IFACE.map(Into::into),
         }
     }
 }
@@ -194,6 +198,8 @@ struct UdpSrcTask {
     need_initial_events: bool,
     need_segment: bool,
     event_receiver: Receiver<gst::Event>,
+    multicast_ifaces: Vec<getifaddrs::Interface>,
+    multicast_addr: Option<IpAddr>,
 }
 
 impl UdpSrcTask {
@@ -205,6 +211,8 @@ impl UdpSrcTask {
             need_initial_events: true,
             need_segment: true,
             event_receiver,
+            multicast_ifaces: Vec::<getifaddrs::Interface>::new(),
+            multicast_addr: None,
         }
     }
 }
@@ -258,7 +266,10 @@ impl TaskImpl for UdpSrcTask {
                                 ["Invalid address '{}' set: {}", addr, err]
                             ));
                         }
-                        Ok(addr) => addr,
+                        Ok(addr) => {
+                            self.multicast_addr = Some(addr);
+                            addr
+                        }
                     },
                 };
                 let port = settings.port;
@@ -363,18 +374,91 @@ impl TaskImpl for UdpSrcTask {
                 })?;
 
                 if addr.is_multicast() {
-                    // TODO: Multicast interface configuration, going to be tricky
+                    if let Some(multicast_iface) = &settings.multicast_iface {
+                        let multi_ifaces: Vec<String> =
+                            multicast_iface.split(',').map(|s| s.to_string()).collect();
+
+                        let iter = getifaddrs::getifaddrs().map_err(|err| {
+                            gst::error_msg!(
+                                gst::ResourceError::OpenRead,
+                                ["Failed to get interfaces: {}", err]
+                            )
+                        })?;
+
+                        iter.for_each(|iface| {
+                            let ip_ver = if iface.address.is_ipv4() {
+                                "IPv4"
+                            } else {
+                                "IPv6"
+                            };
+
+                            for m in &multi_ifaces {
+                                if &iface.name == m {
+                                    self.multicast_ifaces.push(iface.clone());
+                                    gst::debug!(
+                                        CAT,
+                                        obj = self.element,
+                                        "Interface {m} available, version: {ip_ver}"
+                                    );
+                                } else {
+                                    // check if name matches the interface description (Friendly name) on Windows
+                                    #[cfg(windows)]
+                                    if &iface.description == m {
+                                        self.multicast_ifaces.push(iface.clone());
+                                        gst::debug!(
+                                            CAT,
+                                            obj = self.element,
+                                            "Interface {m} available, version: {ip_ver}"
+                                        );
+                                    }
+                                }
+                            }
+                        });
+                    }
+
+                    if self.multicast_ifaces.is_empty() {
+                        gst::warning!(
+                            CAT,
+                            obj = self.element,
+                            "No suitable network interfaces found, adding default iface"
+                        );
+
+                        self.multicast_ifaces.push(getifaddrs::Interface {
+                            name: "default".to_owned(),
+                            #[cfg(windows)]
+                            description: "default".to_owned(),
+                            address: IpAddr::V4(Ipv4Addr::UNSPECIFIED),
+                            #[cfg(not(windows))]
+                            associated_address: None,
+                            netmask: None,
+                            flags: getifaddrs::InterfaceFlags::UP,
+                            index: Some(0),
+                        });
+                    }
+
                     match addr {
                         IpAddr::V4(addr) => {
-                            socket
+                            for iface in &self.multicast_ifaces {
-                                .as_ref()
+                                if !iface.address.is_ipv4() {
-                                .join_multicast_v4(&addr, &Ipv4Addr::new(0, 0, 0, 0))
+                                    gst::debug!(
+                                        CAT,
+                                        "Skipping the IPv6 version of the interface {}",
+                                        iface.name
+                                    );
+                                    continue;
+                                }
+
+                                gst::debug!(CAT, "interface {} joining the multicast", iface.name);
+                                // use the custom written API to be able to pass the interface index
+                                // for all types of target OS
+                                net::imp::join_multicast_v4(socket.as_ref(), &addr, iface)
                                     .map_err(|err| {
                                         gst::error_msg!(
                                             gst::ResourceError::OpenRead,
                                             ["Failed to join multicast group: {}", err]
                                         )
                                     })?;
+                            }
 
                             socket
                                 .as_ref()
@@ -391,12 +475,27 @@ impl TaskImpl for UdpSrcTask {
                                 })?;
                         }
                         IpAddr::V6(addr) => {
-                            socket.as_ref().join_multicast_v6(&addr, 0).map_err(|err| {
+                            for iface in &self.multicast_ifaces {
+                                if !iface.address.is_ipv6() {
+                                    gst::debug!(
+                                        CAT,
+                                        "Skipping the IPv4 version of the interface {}",
+                                        iface.name
+                                    );
+                                    continue;
+                                }
+
+                                gst::debug!(CAT, "interface {} joining the multicast", iface.name);
+                                socket
+                                    .as_ref()
+                                    .join_multicast_v6(&addr, iface.index.unwrap_or(0))
+                                    .map_err(|err| {
                                         gst::error_msg!(
                                             gst::ResourceError::OpenRead,
                                             ["Failed to join multicast group: {}", err]
                                         )
                                     })?;
+                            }
 
                             socket
                                 .as_ref()
@@ -466,6 +565,47 @@ impl TaskImpl for UdpSrcTask {
         async move {
             gst::debug!(CAT, obj = self.element, "Unpreparing Task");
             let udpsrc = self.element.imp();
+            if let Some(reader) = &self.socket {
+                let socket = &reader.get().0;
+                if let Some(addr) = self.multicast_addr {
+                    match addr {
+                        IpAddr::V4(addr) => {
+                            for iface in &self.multicast_ifaces {
+                                if !iface.address.is_ipv4() {
+                                    gst::debug!(
+                                        CAT,
+                                        "Skipping the IPv6 version of the interface {}",
+                                        iface.name
+                                    );
+                                    continue;
+                                }
+
+                                gst::debug!(CAT, "interface {} leaving the multicast", iface.name);
+                                net::imp::leave_multicast_v4(socket.as_ref(), &addr, iface)
+                                    .unwrap();
+                            }
+                        }
+                        IpAddr::V6(addr) => {
+                            for iface in &self.multicast_ifaces {
+                                if !iface.address.is_ipv6() {
+                                    gst::debug!(
+                                        CAT,
+                                        "Skipping the IPv4 version of the interface {}",
+                                        iface.name
+                                    );
+                                    continue;
+                                }
+
+                                gst::debug!(CAT, "interface {} leaving the multicast", iface.name);
+                                socket
+                                    .as_ref()
+                                    .leave_multicast_v6(&addr, iface.index.unwrap_or(0))
+                                    .unwrap();
+                            }
+                        }
+                    }
+                }
+            }
             udpsrc.settings.lock().unwrap().used_socket = None;
             self.element.notify("used-socket");
         }
@@ -825,6 +965,12 @@ impl ObjectImpl for UdpSrc {
                     .maximum(u32::MAX)
                     .default_value(DEFAULT_BUFFER_SIZE)
                     .build(),
+                glib::ParamSpecString::builder("multicast-iface")
+                    .nick("Multicast Interface")
+                    .blurb("The network interface on which to join the multicast group. This allows multiple interfaces
+                        separated by comma. (\"eth0,eth1\")")
+                    .default_value(DEFAULT_MULTICAST_IFACE)
+                    .build(),
 
             ];
 
@@ -898,6 +1044,9 @@ impl ObjectImpl for UdpSrc {
             "buffer-size" => {
                 settings.buffer_size = value.get().expect("type checked upstream");
             }
+            "multicast-iface" => {
+                settings.multicast_iface = value.get().expect("type checked upstream");
+            }
             _ => unimplemented!(),
         }
     }
@@ -925,6 +1074,7 @@ impl ObjectImpl for UdpSrc {
             "retrieve-sender-address" => settings.retrieve_sender_address.to_value(),
             "loop" => settings.multicast_loop.to_value(),
             "buffer-size" => settings.buffer_size.to_value(),
+            "multicast-iface" => settings.multicast_iface.to_value(),
             _ => unimplemented!(),
         }
     }