[FFmpeg-devel] [PATCH] Fix setsockopt IP_MULTICAST_TTL on OpenBSD

[Brad Smith]

On Wed, Jan 12, 2022 at 12:13:14AM -0500, Brad Smith wrote:
> Fix setsockopt() usage on OpenBSD with IP_MULTICAST_TTL. The field
> type should be an unsigned char on anything but Linux.

Based on feedback so far. Here is a much simpler approach to this issue..


diff --git a/libavformat/udp.c b/libavformat/udp.c
index 83c042d079..da1b98890b 100644
--- a/libavformat/udp.c
+++ b/libavformat/udp.c
@@ -164,7 +164,9 @@ static int udp_set_multicast_ttl(int sockfd, int mcastTTL,
 {
 #ifdef IP_MULTICAST_TTL
     if (addr->sa_family == AF_INET) {
-        if (setsockopt(sockfd, IPPROTO_IP, IP_MULTICAST_TTL, &mcastTTL, sizeof(mcastTTL)) < 0) {
+        unsigned char ttl = mcastTTL;  /* ignore the outdated Linux documentation */
+
+        if (setsockopt(sockfd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) < 0) {
             ff_log_net_error(logctx, AV_LOG_ERROR, "setsockopt(IP_MULTICAST_TTL)");
             return ff_neterrno();
         }