[FFmpeg-devel] [PATCH v3 2/3] avformat/udp: Fix IP_MULTICAST_TTL for BSD compatibility

[lance.lmwang at gmail.com]

From: Limin Wang <lance.lmwang at gmail.com>

Suggested by zhilizhao, vlc project has solved the compatibility by
the same way, so I borrowed the comments from vlc project.

Fix #ticket9449

Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
---
 libavformat/udp.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/libavformat/udp.c b/libavformat/udp.c
index 8178d0e..1871acf 100644
--- a/libavformat/udp.c
+++ b/libavformat/udp.c
@@ -164,6 +164,10 @@ static int udp_set_multicast_ttl(int sockfd, int mcastTTL,
 {
     int protocol, cmd;
 
+    /* There is some confusion in the world whether IP_MULTICAST_TTL
+     * takes a byte or an int as an argument.
+     * BSD seems to indicate byte so we are going with that and use
+     * int and fall back to byte to be safe */
     switch (addr->sa_family) {
 #ifdef IP_MULTICAST_TTL
         case AF_INET:
@@ -182,8 +186,15 @@ static int udp_set_multicast_ttl(int sockfd, int mcastTTL,
     }
 
     if (setsockopt(sockfd, protocol, cmd, &mcastTTL, sizeof(mcastTTL)) < 0) {
-        ff_log_net_error(logctx, AV_LOG_ERROR, "setsockopt(IPV4/IPV6 MULTICAST TTL)");
-        return ff_neterrno();
+        /* BSD compatibility */
+        unsigned char ttl;
+
+        ff_log_net_error(logctx, AV_LOG_DEBUG, "setsockopt(IPV4/IPV6 MULTICAST TTL)");
+        ttl = (unsigned char)(( mcastTTL > 255 ) ? 255 : mcastTTL);
+        if (setsockopt(sockfd, protocol, cmd, &ttl, sizeof(ttl)) < 0) {
+            ff_log_net_error(logctx, AV_LOG_ERROR, "setsockopt(IPV4/IPV6 MULTICAST TTL)");
+            return ff_neterrno();
+        }
     }
 
     return 0;
-- 
1.8.3.1