[FFmpeg-devel] [PATCH v3] avformat: enable UDP IPv6 multicast interface selection using zone index

["Ignjatović, Lazar (RS)" <Lazar.Ignjatovic@cubic.com>]

avformat: enable UDP IPv6 multicast interface selection using zone index

Enabled IPv6 interface selection using zone index. Properly resolved
interface index in places where default 0 interface index is used
(marked with TODO: within udp.c). Adjusted binding for multicast sockets
that are used for reading from the network.

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.

Closes: #368

Signed-off-by: Lazar Ignjatovic <Lazar.Ignjatovic@cubic.com>
---
NOTE: Due to comments, this patch is proposed as one of two alternatives
The other alternative uses `localaddr` for defining interfaces.
V1 -> V2 reverted iface resolution for IPv4 MCAST_JOIN_SOURCE_GROUP
V2 -> V3 resolved conflicts


 configure             |  3 ++
 doc/protocols.texi    |  2 +-
 libavformat/network.h |  6 +++
 libavformat/udp.c     | 85 +++++++++++++++++++++++++++++++++++++++----
 4 files changed, 88 insertions(+), 8 deletions(-)

diff --git a/configure b/configure
index 55f1fc354d..96183e58b3 100755
--- a/configure
+++ b/configure
@@ -2311,6 +2311,7 @@ HEADERS_LIST="
     valgrind_valgrind_h
     windows_h
     winsock2_h
+    iphlpapi_h
 "

 INTRINSICS_LIST="
@@ -6483,6 +6484,8 @@ 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 -liphlpapi && network_extralibs="$network_extralibs -liphlpapi" || disable iphlpapi_h
+        check_func_headers iphlpapi.h GetBestInterfaceEx $network_extralibs
     else
         disable network
     fi
diff --git a/doc/protocols.texi b/doc/protocols.texi
index f54600b846..a8892845d3 100644
--- a/doc/protocols.texi
+++ b/doc/protocols.texi
@@ -2027,7 +2027,7 @@ packet bursts.
 Override the local UDP port to bind with.

 @item localaddr=@var{addr}
-Local IP address of a network interface used for sending packets or joining
+Local IPv4 address of a network interface used for sending packets or joining
 multicast groups.

 @item pkt_size=@var{size}
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 c1ebdd1222..fa2f62b0b7 100644
--- a/libavformat/udp.c
+++ b/libavformat/udp.c
@@ -36,6 +36,7 @@
 #include "libavutil/opt.h"
 #include "libavutil/log.h"
 #include "libavutil/time.h"
+#include "libavutil/avstring.h"
 #include "network.h"
 #include "os_support.h"
 #include "url.h"
@@ -220,8 +221,7 @@ 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 = ((struct sockaddr_in6 *)addr)->sin6_scope_id;
         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 +231,39 @@ 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;
+        iface = ((struct sockaddr_in6 *)addr)->sin6_scope_id;
+
+        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 +287,7 @@ 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 = ((struct sockaddr_in6 *)addr)->sin6_scope_id;
         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;
@@ -284,6 +316,9 @@ static int udp_set_multicast_sources(URLContext *h,

             //TODO: Interface index should be looked up from local_addr
             mreqs.gsr_interface = 0;
+            if (level == IPPROTO_IPV6)
+                mreqs.gsr_interface = ((struct sockaddr_in6 *)addr)->sin6_scope_id;
+
             memcpy(&mreqs.gsr_group, addr, addr_len);
             memcpy(&mreqs.gsr_source, &sources[i], sizeof(*sources));

@@ -340,9 +375,24 @@ static int udp_set_url(URLContext *h,
 {
     struct addrinfo *res0;
     int addr_len;
+    const char *host, *sc;
+    char address[1024], scope[1024];

-    res0 = ff_ip_resolve_host(h, hostname, port, SOCK_DGRAM, AF_UNSPEC, 0);
+    if (sc = strchr(hostname, '%')) {
+        av_strlcpy(address, hostname, FFMIN(1024, sc - hostname + 1));
+        av_strlcpy(scope, sc + 1, FFMIN(1024, strlen(hostname) - (sc - hostname)));
+        host = address;
+    } else {
+        host = hostname;
+    }
+
+    res0 = ff_ip_resolve_host(h, host, port, SOCK_DGRAM, AF_UNSPEC, 0);
     if (!res0) return AVERROR(EIO);
+#if HAVE_IPHLPAPI_H || !HAVE_WINSOCK2_H
+    if (res0->ai_family== AF_INET6 && strlen(scope) > 0) {
+        ((struct sockaddr_in6*)res0->ai_addr)->sin6_scope_id = if_nametoindex(scope);
+    }
+#endif
     memcpy(addr, res0->ai_addr, res0->ai_addrlen);
     addr_len = res0->ai_addrlen;
     freeaddrinfo(res0);
@@ -841,8 +891,23 @@ static int udp_open(URLContext *h, const char *uri, int flags)
     if (s->is_multicast && (h->flags & AVIO_FLAG_READ)) {
         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 +920,12 @@ 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 04/11/2024 13:01Z.
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