Hi Peter
On Fri, Aug 08, 2025 at 09:27:35AM +0200, Peter Enderborg wrote:
> This fixes two old TODO's in ipv6 multicast handling.
> If the system as SIOCGIFINDEX ioctl a helper function to iterate over
> all interfaces added to join the multicast group on interface if approperite.
>
> The default value is IN6ADDR_ANY (::) and it then joins all interfaces
> that are up and have multicast support. Local address can be
> specified and then it join ALL interfaces that use that specific
> local address.
>
> Limitations (TODO's)
> Handling when network configuration is changed. if up/down etc.
>
> Signed-off-by: Peter Enderborg <peter...@axis.com>
> ---
> libavformat/udp.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 96 insertions(+), 2 deletions(-)
>
> diff --git a/libavformat/udp.c b/libavformat/udp.c
> index 84f9d3e62e..a0482c122f 100644
> --- a/libavformat/udp.c
> +++ b/libavformat/udp.c
> @@ -68,6 +68,13 @@
> #include "libavutil/thread.h"
> #endif
>
> +#if HAVE_STRUCT_IPV6_MREQ && HAVE_IOCTL_GIFINDEX && defined(IPPROTO_IPV6)
> +#include <sys/types.h>
> +#include <net/if.h>
> +#include <sys/ioctl.h>
> +#include <ifaddrs.h>
> +#endif
> +
> #ifndef IPV6_ADD_MEMBERSHIP
> #define IPV6_ADD_MEMBERSHIP IPV6_JOIN_GROUP
> #define IPV6_DROP_MEMBERSHIP IPV6_LEAVE_GROUP
> @@ -205,6 +212,79 @@ static int udp_set_multicast_ttl(int sockfd, int
> mcastTTL,
>
> return 0;
> }
> +#if HAVE_STRUCT_IPV6_MREQ && HAVE_IOCTL_GIFINDEX && defined(IPPROTO_IPV6)
> +static int udp_ipv6_multicast_iterate(int sockfd, struct sockaddr_in6 *addr,
> + struct sockaddr_in6 *local_addr, int
> mop, void *logctx)
> +{
> + struct in6_addr anyipv6 = IN6ADDR_ANY_INIT;
> + struct ifaddrs *ifal=NULL,*ife=NULL;
> + int iindex_fd = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
> + int membership_changed = 0;
> +
> + if (iindex_fd >= 0 && !getifaddrs(&ifal)) {
> + for(ife=ifal; ife!=NULL; ife=ife->ifa_next) {
> + if (ife->ifa_addr &&
> + (ife->ifa_addr->sa_family == AF_INET6) &&
> + (ife->ifa_flags & IFF_MULTICAST) &&
> + (ife->ifa_flags & IFF_UP)) {
> + if ((!memcmp(&local_addr->sin6_addr, &anyipv6, sizeof(struct
> in6_addr))) ||
> + (!memcmp(&local_addr->sin6_addr, &((struct sockaddr_in6
> *)ife->ifa_addr)->sin6_addr, sizeof(struct in6_addr)))) {
> + struct ifreq if_req;
> + strncpy(if_req.ifr_name, ife->ifa_name, IFNAMSIZ);
> + if (ioctl(iindex_fd, SIOCGIFINDEX, &if_req) != -1) {
> + struct ipv6_mreq mreq6;
> + memcpy(&mreq6.ipv6mr_multiaddr, &addr->sin6_addr,
> sizeof(struct in6_addr));
> + mreq6.ipv6mr_interface = if_req.ifr_ifindex;
> + switch (mop) {
> + case IPV6_JOIN_GROUP:
> + if (setsockopt(sockfd, IPPROTO_IPV6,
> IPV6_ADD_MEMBERSHIP, &mreq6, sizeof(mreq6)) == 0) {
> + membership_changed = 1;
> + } else {
> + /* Subscribe for all ipv6 addresses belong
> to a
> + interface.It can generate EADDRINUSE but
> + is accaptable. */
> + if (errno != EADDRINUSE) {
> + ff_log_net_error(logctx, AV_LOG_ERROR,
> "setsockopt(IPV6_ADD_MEMBERSHIP)");
> + goto error;the patch mixes tabs and spaces, we use only spaces in C files for indention. I will leave the review of teh actual changes to others as I am sure you know much more about ipv6 multicast than i do thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Does the universe only have a finite lifespan? No, its going to go on forever, its just that you wont like living in it. -- Hiranya Peiri
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