From 83d2dc991dfd0a87d6d6e9885aa1d25df134c6f2 Mon Sep 17 00:00:00 2001
From: Yat Ho <lagoho7@gmail.com>
Date: Wed, 27 Mar 2024 16:02:17 +0800
Subject: [PATCH] fix: enable multicast loop

---
 libtransmission/tr-lpd.cc | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/libtransmission/tr-lpd.cc b/libtransmission/tr-lpd.cc
index 95705e1fc..97c66a6a3 100644
--- a/libtransmission/tr-lpd.cc
+++ b/libtransmission/tr-lpd.cc
@@ -394,6 +394,13 @@ private:
                 {
                     return false;
                 }
+
+                // needed to announce to BT clients on the same interface
+                if (setsockopt(sock, IPPROTO_IP, IP_MULTICAST_LOOP, reinterpret_cast<char const*>(&opt_on), sizeof(opt_on)) ==
+                    -1)
+                {
+                    return false;
+                }
             }
             else // TR_AF_INET6
             {
@@ -434,6 +441,17 @@ private:
                 {
                     return false;
                 }
+
+                // needed to announce to BT clients on the same interface
+                if (setsockopt(
+                        sock,
+                        IPPROTO_IPV6,
+                        IPV6_MULTICAST_LOOP,
+                        reinterpret_cast<char const*>(&opt_on),
+                        sizeof(opt_on)) == -1)
+                {
+                    return false;
+                }
             }
         }