net/udp: Support deliver multicast packets back to local apps

Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>

net/inet/ipv4_setsockopt.c

@@ -305,10 +305,6 @@ int ipv4_setsockopt(FAR struct socket *psock, int option,
 
       /* The following IPv4 socket options are defined, but not implemented */
 
-      case IP_MULTICAST_LOOP:         /* Set/read boolean that determines
-                                       * whether sent multicast packets
-                                       * should be looped back to local
-                                       * sockets. */
       case IP_UNBLOCK_SOURCE:         /* Unblock previously blocked multicast
                                        * source */
       case IP_BLOCK_SOURCE:           /* Stop receiving multicast data from
@@ -327,8 +323,12 @@ int ipv4_setsockopt(FAR struct socket *psock, int option,
         nwarn("WARNING: Unimplemented IPv4 option: %d\n", option);
         ret = -ENOSYS;
         break;
-#endif /* CONFIG_NET_IGMP */
 
+      case IP_MULTICAST_LOOP:         /* Set/read boolean that determines
+                                       * whether sent multicast packets
+                                       * should be looped back to local
+                                       * sockets. */
+#endif /* CONFIG_NET_IGMP */
       case IP_PKTINFO:
         {
           FAR struct socket_conn_s *conn;

net/inet/ipv6_setsockopt.c

@@ -137,13 +137,11 @@ int ipv6_setsockopt(FAR struct socket *psock, int option,
         ret = OK;
         break;
       }
-#endif
+#endif /* NET_UDP_HAVE_STACK */
+#endif /* CONFIG_NET_MLD */
 
       /* The following IPv6 socket options are defined, but not implemented */
 
-      case IPV6_MULTICAST_LOOP:   /* Multicast packets are delivered back to
-                                   * the local application */
-#endif
       case IPV6_V6ONLY:           /* Restrict AF_INET6 socket to IPv6
                                    * communications only */
         nwarn("WARNING: Unimplemented IPv6 option: %d\n", option);
@@ -160,6 +158,10 @@ int ipv6_setsockopt(FAR struct socket *psock, int option,
         }
         break;
 
+#ifdef CONFIG_NET_MLD
+      case IPV6_MULTICAST_LOOP:   /* Multicast packets are delivered back to
+                                   * the local application */
+#endif
       case IPV6_RECVPKTINFO:
       case IPV6_RECVHOPLIMIT:
         {

net/udp/udp_send.c

@@ -58,9 +58,67 @@
 
 #include "devif/devif.h"
 #include "inet/inet.h"
+#include "socket/socket.h"
 #include "utils/utils.h"
 #include "udp/udp.h"
 
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: udp_send_loopback
+ *
+ * Description:
+ *   Send a copy of the UDP packet to ourself.
+ *
+ * Input Parameters:
+ *   dev - The device driver structure to use in the send operation
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+#if defined(CONFIG_NET_SOCKOPTS) && \
+    (defined(CONFIG_NET_IGMP) || defined(CONFIG_NET_MLD))
+static void udp_send_loopback(FAR struct net_driver_s *dev)
+{
+  FAR struct iob_s *iob = netdev_iob_clone(dev, true);
+  if (iob == NULL)
+    {
+      nerr("ERROR: IOB clone failed when looping UDP.\n");
+      return;
+    }
+
+#ifdef CONFIG_NET_IPv4
+#ifdef CONFIG_NET_IPv6
+  if (IFF_IS_IPv4(dev->d_flags))
+#endif
+    {
+      ninfo("IPv4 frame\n");
+      NETDEV_RXIPV4(dev);
+      ipv4_input(dev);
+    }
+#endif /* CONFIG_NET_IPv4 */
+
+#ifdef CONFIG_NET_IPv6
+#ifdef CONFIG_NET_IPv4
+  else
+#endif
+    {
+      ninfo("IPv6 frame\n");
+      NETDEV_RXIPV6(dev);
+      ipv6_input(dev);
+    }
+#endif /* CONFIG_NET_IPv6 */
+
+  /* Restore device IOB with backup IOB */
+
+  netdev_iob_replace(dev, iob);
+}
+#endif
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -192,9 +250,7 @@ void udp_send(FAR struct net_driver_s *dev, FAR struct udp_conn_s *conn)
 
 #ifdef CONFIG_NET_IPv4
 #ifdef CONFIG_NET_IPv6
-      if (conn->domain == PF_INET ||
+      if (IFF_IS_IPv4(dev->d_flags))
-          (conn->domain == PF_INET6 &&
-           ip6_is_ipv4addr((FAR struct in6_addr *)conn->u.ipv6.raddr)))
 #endif
         {
           udp->udpchksum = ~udp_ipv4_chksum(dev);
@@ -221,6 +277,32 @@ void udp_send(FAR struct net_driver_s *dev, FAR struct udp_conn_s *conn)
 #ifdef CONFIG_NET_STATISTICS
       g_netstats.udp.sent++;
 #endif
+
+#ifdef CONFIG_NET_SOCKOPTS
+      /* Try loopback multicast to ourself. */
+
+#ifdef CONFIG_NET_IGMP
+      if (_SO_GETOPT(conn->sconn.s_options, IP_MULTICAST_LOOP) &&
+#ifdef CONFIG_NET_IPv6
+          IFF_IS_IPv4(dev->d_flags) &&
+#endif
+          IN_MULTICAST(NTOHL(raddr)))
+        {
+          udp_send_loopback(dev);
+        }
+#endif /* CONFIG_NET_IGMP */
+
+#ifdef CONFIG_NET_MLD
+      if (_SO_GETOPT(conn->sconn.s_options, IPV6_MULTICAST_LOOP) &&
+#ifdef CONFIG_NET_IPv4
+          IFF_IS_IPv6(dev->d_flags) &&
+#endif
+          IN6_IS_ADDR_MULTICAST((FAR struct in6_addr *)conn->u.ipv6.raddr))
+        {
+          udp_send_loopback(dev);
+        }
+#endif /* CONFIG_NET_MLD */
+#endif /* CONFIG_NET_SOCKOPTS */
     }
 }