From bfa2a06d17166b3703a9833b4cd6396711230fb2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C3=ABl=20Carr=C3=A9?= <funman@videolan.org>
Date: Fri, 13 Sep 2024 16:28:17 +0200
Subject: [PATCH] udpsink: set ifindex

---
 lib/upipe-modules/upipe_udp_sink.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/lib/upipe-modules/upipe_udp_sink.c b/lib/upipe-modules/upipe_udp_sink.c
index f34cd502e..2ec6ee45e 100644
--- a/lib/upipe-modules/upipe_udp_sink.c
+++ b/lib/upipe-modules/upipe_udp_sink.c
@@ -54,6 +54,7 @@
 #include <sys/socket.h>
 #include <errno.h>
 #include <assert.h>
+#include <netinet/in.h>
 
 /** tolerance for late packets */
 #define SYSTIME_TOLERANCE UCLOCK_FREQ
@@ -289,6 +290,17 @@ static bool upipe_udpsink_output(struct upipe *upipe, struct uref *uref,
             .msg_flags = 0,
         };
 
+        uint8_t ancillary[CMSG_SPACE(sizeof(struct in_pktinfo))];
+        uint64_t ifindex;
+        if (ubase_check(uref_block_get_net_ifindex(uref, &ifindex))) {
+            struct in_pktinfo *info = (void*)ancillary;
+            info->ipi_ifindex = ifindex;
+            info->ipi_spec_dst.s_addr = 0,
+            info->ipi_addr.s_addr = 0,
+            msghdr.msg_control = ancillary;
+            msghdr.msg_controllen = sizeof(ancillary);
+        }
+
         ssize_t ret = sendmsg(upipe_udpsink->fd, &msghdr, 0);
         uref_block_iovec_unmap(uref, 0, -1, iovecs);