Add netconn_join_leave_group_netif() that takes netif index as argument

src/api/api_lib.c

@@ -1129,6 +1129,48 @@ netconn_join_leave_group(struct netconn *conn,
 
   return err;
 }
+/**
+ * @ingroup netconn_udp
+ * Join multicast groups for UDP netconns.
+ *
+ * @param conn the UDP netconn for which to change multicast addresses
+ * @param multiaddr IP address of the multicast group to join or leave
+ * @param if_idx the index of the netif
+ * @param join_or_leave flag whether to send a join- or leave-message
+ * @return ERR_OK if the action was taken, any err_t on error
+ */
+err_t
+netconn_join_leave_group_netif(struct netconn *conn,
+                               const ip_addr_t *multiaddr,
+                               u8_t if_idx,
+                               enum netconn_igmp join_or_leave)
+{
+  API_MSG_VAR_DECLARE(msg);
+  err_t err;
+
+  LWIP_ERROR("netconn_join_leave_group: invalid conn",  (conn != NULL), return ERR_ARG;);
+
+  API_MSG_VAR_ALLOC(msg);
+
+#if LWIP_IPV4
+  /* Don't propagate NULL pointer (IP_ADDR_ANY alias) to subsequent functions */
+  if (multiaddr == NULL) {
+    multiaddr = IP4_ADDR_ANY;
+  }
+  if (if_idx == NETIF_NO_INDEX) {
+    return ERR_IF;
+  }
+#endif /* LWIP_IPV4 */
+
+  API_MSG_VAR_REF(msg).conn = conn;
+  API_MSG_VAR_REF(msg).msg.jl.multiaddr = API_MSG_VAR_REF(multiaddr);
+  API_MSG_VAR_REF(msg).msg.jl.if_idx = if_idx;
+  API_MSG_VAR_REF(msg).msg.jl.join_or_leave = join_or_leave;
+  err = netconn_apimsg(lwip_netconn_do_join_leave_group_netif, &API_MSG_VAR_REF(msg));
+  API_MSG_VAR_FREE(msg);
+
+  return err;
+}
 #endif /* LWIP_IGMP || (LWIP_IPV6 && LWIP_IPV6_MLD) */
 
 #if LWIP_DNS

src/api/api_msg.c

@@ -1995,6 +1995,67 @@ lwip_netconn_do_join_leave_group(void *m)
   }
   TCPIP_APIMSG_ACK(msg);
 }
+/**
+ * Join multicast groups for UDP netconns.
+ * Called from netconn_join_leave_group_netif
+ *
+ * @param m the api_msg pointing to the connection
+ */
+void
+lwip_netconn_do_join_leave_group_netif(void *m)
+{
+  struct api_msg *msg = (struct api_msg*)m;
+  struct netif *netif;
+
+  if (msg->msg.jl.if_idx == NETIF_NO_INDEX) {
+    msg->err = ERR_IF;
+    goto done;
+  }
+
+  netif = netif_get_by_index(msg->msg.jl.if_idx);
+  if (netif == NULL) {
+    msg->err = ERR_IF;
+    goto done;
+  }
+
+  msg->err = ERR_CONN;
+  if (msg->conn->pcb.tcp != NULL) {
+    if (NETCONNTYPE_GROUP(msg->conn->type) == NETCONN_UDP) {
+#if LWIP_UDP
+#if LWIP_IPV6 && LWIP_IPV6_MLD
+      if (NETCONNTYPE_ISIPV6(msg->conn->type)) {
+        if (msg->msg.jl.join_or_leave == NETCONN_JOIN) {
+          msg->err = mld6_joingroup_netif(netif,
+            ip_2_ip6(API_EXPR_REF(msg->msg.jl.multiaddr)));
+        } else {
+          msg->err = mld6_leavegroup_netif(netif,
+            ip_2_ip6(API_EXPR_REF(msg->msg.jl.multiaddr)));
+        }
+      }
+      else
+#endif /* LWIP_IPV6 && LWIP_IPV6_MLD */
+      {
+#if LWIP_IGMP
+        if (msg->msg.jl.join_or_leave == NETCONN_JOIN) {
+          msg->err = igmp_joingroup_netif(netif,
+            ip_2_ip4(API_EXPR_REF(msg->msg.jl.multiaddr)));
+        } else {
+          msg->err = igmp_leavegroup_netif(netif,
+            ip_2_ip4(API_EXPR_REF(msg->msg.jl.multiaddr)));
+        }
+#endif /* LWIP_IGMP */
+      }
+#endif /* LWIP_UDP */
+#if (LWIP_TCP || LWIP_RAW)
+    } else {
+      msg->err = ERR_VAL;
+#endif /* (LWIP_TCP || LWIP_RAW) */
+    }
+  }
+
+done:
+  TCPIP_APIMSG_ACK(msg);
+}
 #endif /* LWIP_IGMP || (LWIP_IPV6 && LWIP_IPV6_MLD) */
 
 #if LWIP_DNS

src/include/lwip/api.h

@@ -341,6 +341,8 @@ err_t   netconn_shutdown(struct netconn *conn, u8_t shut_rx, u8_t shut_tx);
 #if LWIP_IGMP || (LWIP_IPV6 && LWIP_IPV6_MLD)
 err_t   netconn_join_leave_group(struct netconn *conn, const ip_addr_t *multiaddr,
                              const ip_addr_t *netif_addr, enum netconn_igmp join_or_leave);
+err_t   netconn_join_leave_group_netif(struct netconn *conn, const ip_addr_t *multiaddr,
+                             u8_t if_idx, enum netconn_igmp join_or_leave);
 #endif /* LWIP_IGMP || (LWIP_IPV6 && LWIP_IPV6_MLD) */
 #if LWIP_DNS
 #if LWIP_IPV4 && LWIP_IPV6

src/include/lwip/priv/api_msg.h

@@ -139,6 +139,7 @@ struct api_msg {
     struct {
       API_MSG_M_DEF_C(ip_addr_t, multiaddr);
       API_MSG_M_DEF_C(ip_addr_t, netif_addr);
+      u8_t if_idx;
       enum netconn_igmp join_or_leave;
     } jl;
 #endif /* LWIP_IGMP || (LWIP_IPV6 && LWIP_IPV6_MLD) */
@@ -205,6 +206,7 @@ void lwip_netconn_do_close           (void *m);
 void lwip_netconn_do_shutdown        (void *m);
 #if LWIP_IGMP || (LWIP_IPV6 && LWIP_IPV6_MLD)
 void lwip_netconn_do_join_leave_group(void *m);
+void lwip_netconn_do_join_leave_group_netif(void *m);
 #endif /* LWIP_IGMP || (LWIP_IPV6 && LWIP_IPV6_MLD) */
 
 #if LWIP_DNS