Add functions to join/leave IGMP group by netif

Existing functions are based on IP address, but the address is used
only to look up which netif to act on. The netif-based core code is
extracted to new exported functions.

If you have a netif handle, this makes it easier to join/leave
groups, without the need to convert to IP address first only for the
IGMP code to convert back to netif.

src/core/ipv4/igmp.c

@@ -489,7 +489,6 @@ err_t
 igmp_joingroup(const ip4_addr_t *ifaddr, const ip4_addr_t *groupaddr)
 {
   err_t        err = ERR_VAL; /* no matching interface */
-  struct igmp_group *group;
   struct netif *netif;
 
   /* make sure it is multicast address */
@@ -501,22 +500,54 @@ igmp_joingroup(const ip4_addr_t *ifaddr, const ip4_addr_t *groupaddr)
   while (netif != NULL) {
     /* Should we join this interface ? */
     if ((netif->flags & NETIF_FLAG_IGMP) && ((ip4_addr_isany(ifaddr) || ip4_addr_cmp(netif_ip4_addr(netif), ifaddr)))) {
+      err = igmp_joingroup_netif(netif, groupaddr);
+      if (err != ERR_OK) {
+        /* Return an error even if some network interfaces are joined */
+        /** @todo undo any other netif already joined */
+        return err;
+      }
+    }
+    /* proceed to next network interface */
+    netif = netif->next;
+  }
+
+  return err;
+}
+
+/**
+ * Join a group on one network interface.
+ *
+ * @param netif the network interface which should join a new group
+ * @param groupaddr the ip address of the group which to join
+ * @return ERR_OK if group was joined on the netif, an err_t otherwise
+ */
+err_t  igmp_joingroup_netif(struct netif *netif, const ip4_addr_t *groupaddr)
+{
+  struct igmp_group *group;
+
+  /* make sure it is multicast address */
+  LWIP_ERROR("igmp_joingroup_netif: attempt to join non-multicast address", ip4_addr_ismulticast(groupaddr), return ERR_VAL;);
+  LWIP_ERROR("igmp_joingroup_netif: attempt to join allsystems address", (!ip4_addr_cmp(groupaddr, &allsystems)), return ERR_VAL;);
+
+  /* make sure it is an igmp-enabled netif */
+  LWIP_ERROR("igmp_joingroup_netif: attempt to join on non-IGMP netif", netif->flags & NETIF_FLAG_IGMP, return ERR_VAL;);
+
   /* find group or create a new one if not found */
   group = igmp_lookup_group(netif, groupaddr);
 
   if (group != NULL) {
     /* This should create a new group, check the state to make sure */
     if (group->group_state != IGMP_GROUP_NON_MEMBER) {
-          LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup: join to group not in state IGMP_GROUP_NON_MEMBER\n"));
+      LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup_netif: join to group not in state IGMP_GROUP_NON_MEMBER\n"));
     } else {
       /* OK - it was new group */
-          LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup: join to new group: "));
+      LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup_netif: join to new group: "));
       ip4_addr_debug_print(IGMP_DEBUG, groupaddr);
       LWIP_DEBUGF(IGMP_DEBUG, ("\n"));
 
       /* If first use of the group, allow the group at the MAC level */
       if ((group->use==0) && (netif->igmp_mac_filter != NULL)) {
-            LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup: igmp_mac_filter(ADD "));
+        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup_netif: igmp_mac_filter(ADD "));
         ip4_addr_debug_print(IGMP_DEBUG, groupaddr);
         LWIP_DEBUGF(IGMP_DEBUG, (") on if %p\n", (void*)netif));
         netif->igmp_mac_filter(netif, groupaddr, IGMP_ADD_MAC_FILTER);
@@ -533,19 +564,11 @@ igmp_joingroup(const ip4_addr_t *ifaddr, const ip4_addr_t *groupaddr)
     /* Increment group use */
     group->use++;
     /* Join on this interface */
-        err = ERR_OK;
+    return ERR_OK;
   } else {
-        /* Return an error even if some network interfaces are joined */
+    LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup_netif: Not enough memory to join to group\n"));
-        /** @todo undo any other netif already joined */
-        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_joingroup: Not enough memory to join to group\n"));
     return ERR_MEM;
   }
-    }
-    /* proceed to next network interface */
-    netif = netif->next;
-  }
-
-  return err;
 }
 
 /**
@@ -559,7 +582,6 @@ err_t
 igmp_leavegroup(const ip4_addr_t *ifaddr, const ip4_addr_t *groupaddr)
 {
   err_t        err = ERR_VAL; /* no matching interface */
-  struct igmp_group *group;
   struct netif *netif;
 
   /* make sure it is multicast address */
@@ -571,12 +593,43 @@ igmp_leavegroup(const ip4_addr_t *ifaddr, const ip4_addr_t *groupaddr)
   while (netif != NULL) {
     /* Should we leave this interface ? */
     if ((netif->flags & NETIF_FLAG_IGMP) && ((ip4_addr_isany(ifaddr) || ip4_addr_cmp(netif_ip4_addr(netif), ifaddr)))) {
+      err_t res = igmp_leavegroup_netif(netif, groupaddr);
+      if (err != ERR_OK) {
+        /* Store this result if we have not yet gotten a success */
+        err = res;
+      }
+    }
+    /* proceed to next network interface */
+    netif = netif->next;
+  }
+
+  return err;
+}
+
+/**
+ * Leave a group on one network interface.
+ *
+ * @param netif the network interface which should leave a group
+ * @param groupaddr the ip address of the group which to leave
+ * @return ERR_OK if group was left on the netif, an err_t otherwise
+ */
+err_t igmp_leavegroup_netif(struct netif *netif, const ip4_addr_t *groupaddr)
+{
+  struct igmp_group *group;
+
+  /* make sure it is multicast address */
+  LWIP_ERROR("igmp_leavegroup_netif: attempt to leave non-multicast address", ip4_addr_ismulticast(groupaddr), return ERR_VAL;);
+  LWIP_ERROR("igmp_leavegroup_netif: attempt to leave allsystems address", (!ip4_addr_cmp(groupaddr, &allsystems)), return ERR_VAL;);
+
+  /* make sure it is an igmp-enabled netif */
+  LWIP_ERROR("igmp_leavegroup_netif: attempt to leave on non-IGMP netif", netif->flags & NETIF_FLAG_IGMP, return ERR_VAL;);
+
   /* find group */
   group = igmp_lookfor_group(netif, groupaddr);
 
   if (group != NULL) {
     /* Only send a leave if the flag is set according to the state diagram */
-        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: Leaving group: "));
+    LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup_netif: Leaving group: "));
     ip4_addr_debug_print(IGMP_DEBUG, groupaddr);
     LWIP_DEBUGF(IGMP_DEBUG, ("\n"));
 
@@ -584,20 +637,20 @@ igmp_leavegroup(const ip4_addr_t *ifaddr, const ip4_addr_t *groupaddr)
     if (group->use <= 1) {
       /* If we are the last reporter for this group */
       if (group->last_reporter_flag) {
-            LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: sending leaving group\n"));
+        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup_netif: sending leaving group\n"));
         IGMP_STATS_INC(igmp.tx_leave);
         igmp_send(group, IGMP_LEAVE_GROUP);
       }
 
       /* Disable the group at the MAC level */
       if (netif->igmp_mac_filter != NULL) {
-            LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: igmp_mac_filter(DEL "));
+        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup_netif: igmp_mac_filter(DEL "));
         ip4_addr_debug_print(IGMP_DEBUG, groupaddr);
         LWIP_DEBUGF(IGMP_DEBUG, (") on if %p\n", (void*)netif));
         netif->igmp_mac_filter(netif, groupaddr, IGMP_DEL_MAC_FILTER);
       }
 
-          LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: remove group: "));
+      LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup_netif: remove group: "));
       ip4_addr_debug_print(IGMP_DEBUG, groupaddr);
       LWIP_DEBUGF(IGMP_DEBUG, ("\n"));
 
@@ -607,18 +660,11 @@ igmp_leavegroup(const ip4_addr_t *ifaddr, const ip4_addr_t *groupaddr)
       /* Decrement group use */
       group->use--;
     }
-        /* Leave on this interface */
+    return ERR_OK;
-        err = ERR_OK;
   } else {
-        /* It's not a fatal error on "leavegroup" */
+    LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup_netif: not member of group\n"));
-        LWIP_DEBUGF(IGMP_DEBUG, ("igmp_leavegroup: not member of group\n"));
+    return ERR_VAL;
   }
-    }
-    /* proceed to next network interface */
-    netif = netif->next;
-  }
-
-  return err;
 }
 
 /**

src/include/lwip/igmp.h

@@ -94,7 +94,9 @@ void   igmp_report_groups(struct netif *netif);
 struct igmp_group *igmp_lookfor_group(struct netif *ifp, const ip4_addr_t *addr);
 void   igmp_input(struct pbuf *p, struct netif *inp, const ip4_addr_t *dest);
 err_t  igmp_joingroup(const ip4_addr_t *ifaddr, const ip4_addr_t *groupaddr);
+err_t  igmp_joingroup_netif(struct netif *netif, const ip4_addr_t *groupaddr);
 err_t  igmp_leavegroup(const ip4_addr_t *ifaddr, const ip4_addr_t *groupaddr);
+err_t  igmp_leavegroup_netif(struct netif *netif, const ip4_addr_t *groupaddr);
 void   igmp_tmr(void);
 
 #ifdef __cplusplus