[FFmpeg-devel] [PATCH] avformat: enable UDP IPv6 multicast interface selection
Rémi Denis-Courmont
remi at remlab.net
Fri Mar 15 18:26:38 EET 2024
Le jeudi 14 mars 2024, 11:22:40 EET Ignjatović, Lazar (RS) a écrit :
> avformat: enable UDP IPv6 multicast interface selection
>
> localaddr option now properly works with IPv6 addresses. Properly resolved
> interface index in places where default 0 interface index is used (marked
> with TODO: within udp.c). Added SO_BINDTODEVICE for mcast sockets that are
> used for reading from the network.
AFAIK, that is privileged, and is not intended for the purpose of scoping
multicast.Where the need arises to specify an interface for multicast, there
is typically a dedicated ioctl or field of an ioctl.
> Need for this arises from the fact that
> [ffx1::*] and [ffx2::*] mcast addresses need to have a defined interface
> for binding to avoid ambiguity between multiple link-local networks on the
> same host. Failing to set this option causes errors on Linux systems for
> interface and link-local scopes.
>
> For mcast addresses, bind to mcast address is attempted as before. In case
> that this fails, which will happen on Windows, socket is bound to
> INADDR_ANY/IN6ADDR_ANY_INIT depending on address family. Actual interface
> selection is performed using udp_set_multicast_interface to point to the
> desired interface for sending/listening.
>
> Utilization of sin6_scope_id field enables usage and adequate resolving of
> IPv6 addresses that utilize zone index (e.g. fe80::1ff:fe23:4567:890a%eth2 )
> This is not fully supported on Windows, thus relying on this field is not
> done on Windows systems.
>
> Closes: #368
>
> Signed-off-by: Lazar Ignjatovic <Lazar.Ignjatovic at cubic.com>
> ---
> configure | 3 ++
> libavformat/ip.c | 45 ++++++++++++++++++++++++
> libavformat/ip.h | 6 ++++
> libavformat/network.h | 6 ++++
> libavformat/udp.c | 80 ++++++++++++++++++++++++++++++++++++++-----
> 5 files changed, 132 insertions(+), 8 deletions(-)
>
> diff --git a/configure b/configure
> index c34bdd13f5..77f03948ce 100755
> --- a/configure
> +++ b/configure
> @@ -2256,6 +2256,7 @@ HEADERS_LIST="
> valgrind_valgrind_h
> windows_h
> winsock2_h
> + iphlpapi_h
> "
>
> INTRINSICS_LIST="
> @@ -6408,6 +6409,8 @@ if ! disabled network; then
> check_struct winsock2.h "struct sockaddr" sa_len
> check_type ws2tcpip.h "struct sockaddr_in6"
> check_type ws2tcpip.h "struct sockaddr_storage"
> + check_headers iphlpapi.h && network_extralibs+=" -liphlpapi" ||
> disable iphlpapi_h + check_func_headers iphlpapi.h
> GetBestInterfaceEx
> else
> disable network
> fi
> diff --git a/libavformat/ip.c b/libavformat/ip.c
> index b2c7ef07e5..4f2d998c34 100644
> --- a/libavformat/ip.c
> +++ b/libavformat/ip.c
> @@ -18,6 +18,9 @@
> * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> */
>
> +#define _DEFAULT_SOURCE
> +#define _SVID_SOURCE
> +
> #include <string.h>
> #include "ip.h"
> #include "libavutil/avstring.h"
> @@ -159,3 +162,45 @@ void ff_ip_reset_filters(IPSourceFilters *filters)
> filters->nb_include_addrs = 0;
> filters->nb_exclude_addrs = 0;
> }
> +
> +unsigned int ff_ip_resolve_interface_index(struct sockaddr_storage
> *local_addr) +{
> +#if HAVE_WINSOCK2_H && HAVE_IPHLPAPI_H
> + DWORD retval;
> + unsigned long iface;
> +
> + if (local_addr == NULL)
> + return 0;
> +
> + retval = GetBestInterfaceEx((struct sockaddr*)local_addr, &iface);
> + if (retval == NO_ERROR)
> + return iface;
> +
> + return 0;
> +#elif !HAVE_WINSOCK2_H
> + struct ifaddrs *ifaddr, *ifa;
> +
> + if (local_addr == NULL)
> + return 0;
> +
> + /* Special case for link-local addresses, relevant interface is stored
> in sin6_scope_id */ +#if HAVE_STRUCT_SOCKADDR_IN6 &&
> defined(IN6_IS_ADDR_LINKLOCAL)
> + if (local_addr->ss_family == AF_INET6 &&
> IN6_IS_ADDR_LINKLOCAL(&((struct sockaddr_in6*)local_addr)->sin6_addr)) {
Invalid cast, breaks aliasing, AFAICT.
> +
> unsigned int interface;
> + interface = ((struct sockaddr_in6*)local_addr)->sin6_scope_id;
> +
> + if (interface != 0)
> + return interface;
> + }
> +#endif
> + if (getifaddrs(&ifaddr) == -1)
> + return 0;
> +
> + for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
> + if (ifa->ifa_addr != NULL && compare_addr((struct
> sockaddr_storage*)ifa->ifa_addr, local_addr) == 0) + return
> if_nametoindex(ifa->ifa_name);
> + }
> +
> + return 0;
> +#endif
> +}
> diff --git a/libavformat/ip.h b/libavformat/ip.h
> index b76cdab91c..4085e96f08 100644
> --- a/libavformat/ip.h
> +++ b/libavformat/ip.h
> @@ -69,4 +69,10 @@ int ff_ip_parse_blocks(void *log_ctx, const char *buf,
> IPSourceFilters *filters) */
> void ff_ip_reset_filters(IPSourceFilters *filters);
>
> +/**
> + * Resolves IP address to an associated interface index
> + * @return interface index, 0 as default interface value on error
> + */
> +unsigned int ff_ip_resolve_interface_index(struct sockaddr_storage
> *local_addr); +
> #endif /* AVFORMAT_IP_H */
> diff --git a/libavformat/network.h b/libavformat/network.h
> index ca214087fc..2461b651d4 100644
> --- a/libavformat/network.h
> +++ b/libavformat/network.h
> @@ -38,6 +38,10 @@
> #include <winsock2.h>
> #include <ws2tcpip.h>
>
> +#if HAVE_IPHLPAPI_H
> +#include <iphlpapi.h>
> +#endif
> +
> #ifndef EPROTONOSUPPORT
> #define EPROTONOSUPPORT WSAEPROTONOSUPPORT
> #endif
> @@ -64,6 +68,8 @@ int ff_neterrno(void);
> #include <netinet/in.h>
> #include <netinet/tcp.h>
> #include <netdb.h>
> +#include <net/if.h>
> +#include <ifaddrs.h>
>
> #define ff_neterrno() AVERROR(errno)
> #endif /* HAVE_WINSOCK2_H */
> diff --git a/libavformat/udp.c b/libavformat/udp.c
> index d9514f5026..9b8ca74282 100644
> --- a/libavformat/udp.c
> +++ b/libavformat/udp.c
> @@ -220,8 +220,7 @@ static int udp_join_multicast_group(int sockfd, struct
> sockaddr *addr, struct ipv6_mreq mreq6;
>
> memcpy(&mreq6.ipv6mr_multiaddr, &(((struct sockaddr_in6
> *)addr)->sin6_addr), sizeof(struct in6_addr)); - //TODO: Interface
> index should be looked up from local_addr - mreq6.ipv6mr_interface =
> 0;
> + mreq6.ipv6mr_interface = ff_ip_resolve_interface_index((struct
> sockaddr_storage *)local_addr); if (setsockopt(sockfd, IPPROTO_IPV6,
> IPV6_ADD_MEMBERSHIP, &mreq6, sizeof(mreq6)) < 0) { ff_log_net_error(logctx,
> AV_LOG_ERROR, "setsockopt(IPV6_ADD_MEMBERSHIP)"); return ff_neterrno();
> @@ -231,6 +230,38 @@ static int udp_join_multicast_group(int sockfd, struct
> sockaddr *addr, return 0;
> }
>
> +static int udp_set_multicast_interface(int sockfd, struct sockaddr *addr,
> + struct sockaddr *local_addr, void
> *logctx) +{
> +#ifdef IP_MULTICAST_IF
> + if (addr->sa_family == AF_INET) {
> + struct ip_mreq mreq;
> +
> + mreq.imr_multiaddr.s_addr = ((struct sockaddr_in
> *)addr)->sin_addr.s_addr; + if (local_addr)
> + mreq.imr_interface = ((struct sockaddr_in
> *)local_addr)->sin_addr; + else
> + mreq.imr_interface.s_addr = INADDR_ANY;
> +
> + if (setsockopt(sockfd, IPPROTO_IP, IP_MULTICAST_IF, (const void
> *)&mreq, sizeof(mreq)) < 0) { + ff_log_net_error(logctx,
> AV_LOG_ERROR, "setsockopt(IP_MULTICAST_IF)"); + return
> ff_neterrno();
> + }
> + }
> +#endif
> +#if defined(IPV6_MULTICAST_IF) && defined(IPPROTO_IPV6)
> + if (addr->sa_family == AF_INET6) {
> + unsigned int iface = ff_ip_resolve_interface_index((struct
> sockaddr_storage *)local_addr); +
> + if (setsockopt(sockfd, IPPROTO_IPV6, IPV6_MULTICAST_IF, &iface,
> sizeof(unsigned int)) < 0) { + ff_log_net_error(logctx,
> AV_LOG_ERROR, "setsockopt(IPV6_MULTICAST_IF)"); + return
> ff_neterrno();
> + }
> + }
> +#endif
> + return 0;
> +}
> +
> static int udp_leave_multicast_group(int sockfd, struct sockaddr *addr,
> struct sockaddr *local_addr, void
> *logctx) {
> @@ -254,8 +285,7 @@ static int udp_leave_multicast_group(int sockfd, struct
> sockaddr *addr, struct ipv6_mreq mreq6;
>
> memcpy(&mreq6.ipv6mr_multiaddr, &(((struct sockaddr_in6
> *)addr)->sin6_addr), sizeof(struct in6_addr)); - //TODO: Interface
> index should be looked up from local_addr - mreq6.ipv6mr_interface =
> 0;
> + mreq6.ipv6mr_interface = ff_ip_resolve_interface_index((struct
> sockaddr_storage *)local_addr); if (setsockopt(sockfd, IPPROTO_IPV6,
> IPV6_DROP_MEMBERSHIP, &mreq6, sizeof(mreq6)) < 0) {
> ff_log_net_error(logctx, AV_LOG_ERROR, "setsockopt(IPV6_DROP_MEMBERSHIP)");
> return -1;
> @@ -282,8 +312,7 @@ static int udp_set_multicast_sources(URLContext *h,
> struct group_source_req mreqs;
> int level = addr->sa_family == AF_INET ? IPPROTO_IP :
> IPPROTO_IPV6;
>
> - //TODO: Interface index should be looked up from local_addr
> - mreqs.gsr_interface = 0;
> + mreqs.gsr_interface =
> ff_ip_resolve_interface_index(local_addr); memcpy(&mreqs.gsr_group, addr,
> addr_len);
> memcpy(&mreqs.gsr_source, &sources[i], sizeof(*sources));
>
> @@ -839,10 +868,39 @@ static int udp_open(URLContext *h, const char *uri,
> int flags) * port. This fails on windows. This makes sending to the same
> address * using sendto() fail, so only do it if we're opened in read-only
> mode. */ if (s->is_multicast && (h->flags & AVIO_FLAG_READ)) {
> +#if defined(SO_BINDTODEVICE) && !HAVE_WINSOCK2_H
> + {
> + struct ifreq ifr;
> + unsigned int iface;
> + iface = ff_ip_resolve_interface_index((struct sockaddr_storage
> *)&s->local_addr_storage); + memset(&ifr, 0, sizeof(ifr));
> +
> + if (if_indextoname(iface, ifr.ifr_name)) {
> + if (setsockopt(udp_fd, SOL_SOCKET, SO_BINDTODEVICE, (void
> *)&ifr, sizeof(ifr)) < 0) { + perror("setsockopt
> SO_BINDTODEVICE");
> + }
> + }
> + }
> +#endif // defined(SO_BINDTODEVICE) && !HAVE_WINSOCK2_H
> bind_ret = bind(udp_fd,(struct sockaddr *)&s->dest_addr, len);
> }
> - /* bind to the local address if not multicast or if the multicast
> - * bind failed */
> +
> + /* bind to ADDR_ANY if the multicast bind failed */
> + if (s->is_multicast && bind_ret < 0) {
> + struct addrinfo *res;
> +
> + if (s->dest_addr.ss_family == AF_INET)
> + res = ff_ip_resolve_host(h, "0.0.0.0", 0, SOCK_DGRAM,
> AF_UNSPEC, 0); + else if (s->dest_addr.ss_family == AF_INET6)
> + res = ff_ip_resolve_host(h, "::", 0, SOCK_DGRAM, AF_UNSPEC, 0);
> +
> + if (res && res->ai_addr) {
> + bind_ret = bind(udp_fd, res->ai_addr, res->ai_addrlen);
> + }
> +
> + freeaddrinfo(res);
> + }
> +
> /* the bind is needed to give a port to the socket now */
> if (bind_ret < 0 && bind(udp_fd,(struct sockaddr *)&my_addr, len) < 0)
> { ff_log_net_error(h, AV_LOG_ERROR, "bind failed");
> @@ -855,6 +913,12 @@ static int udp_open(URLContext *h, const char *uri, int
> flags) s->local_port = udp_port(&my_addr, len);
>
> if (s->is_multicast) {
> + if ((ret = udp_set_multicast_interface(udp_fd,
> + (struct sockaddr *)&s->dest_addr,
> + (struct sockaddr
> *)&s->local_addr_storage, + h)) < 0)
> + goto fail;
> +
> if (h->flags & AVIO_FLAG_WRITE) {
> /* output */
> if ((ret = udp_set_multicast_ttl(udp_fd, s->ttl, (struct
> sockaddr *)&s->dest_addr, h)) < 0) --
> 2.41.0.windows.2
>
>
> This message has been marked as Public on 03/14/2024 09:22Z.
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