Add functions to join/leave v6 multicast 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
mld6 code to convert back to netif.

src/core/ipv6/mld6.c

@@ -327,7 +327,6 @@ err_t
 mld6_joingroup(const ip6_addr_t *srcaddr, const ip6_addr_t *groupaddr)
 {
   err_t         err = ERR_VAL; /* no matching interface */
-  struct mld_group  *group;
   struct netif *netif;
   u8_t          match;
   u8_t          i;
@@ -350,6 +349,31 @@ mld6_joingroup(const ip6_addr_t *srcaddr, const ip6_addr_t *groupaddr)
       }
     }
     if (match) {
+      err = mld6_joingroup_netif(netif, groupaddr);
+      if (err != ERR_OK) {
+        return err;
+      }
+    }
+
+    /* proceed to next network interface */
+    netif = netif->next;
+  }
+
+  return err;
+}
+
+/**
+ * Join a group on a network interface.
+ *
+ * @param netif the network interface which should join a new group.
+ * @param groupaddr the ipv6 address of the group to join
+ * @return ERR_OK if group was joined on the netif, an err_t otherwise
+ */
+err_t
+mld6_joingroup_netif(struct netif *netif, const ip6_addr_t *groupaddr)
+{
+  struct mld_group *group;
+
   /* find group or create a new one if not found */
   group = mld6_lookfor_group(netif, groupaddr);
 
@@ -373,14 +397,7 @@ mld6_joingroup(const ip6_addr_t *srcaddr, const ip6_addr_t *groupaddr)
 
   /* Increment group use */
   group->use++;
-      err = ERR_OK;
+  return ERR_OK;
-    }
-
-    /* proceed to next network interface */
-    netif = netif->next;
-  }
-
-  return err;
 }
 
 /**
@@ -395,7 +412,6 @@ err_t
 mld6_leavegroup(const ip6_addr_t *srcaddr, const ip6_addr_t *groupaddr)
 {
   err_t         err = ERR_VAL; /* no matching interface */
-  struct mld_group  *group;
   struct netif *netif;
   u8_t          match;
   u8_t          i;
@@ -418,6 +434,31 @@ mld6_leavegroup(const ip6_addr_t *srcaddr, const ip6_addr_t *groupaddr)
       }
     }
     if (match) {
+      err_t res = mld6_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 a network interface.
+ *
+ * @param netif the network interface which should leave the group.
+ * @param groupaddr the ipv6 address of the group to leave
+ * @return ERR_OK if group was left on the netif, an err_t otherwise
+ */
+err_t
+mld6_leavegroup_netif(struct netif *netif, const ip6_addr_t *groupaddr)
+{
+  struct mld_group *group;
+
   /* find group */
   group = mld6_lookfor_group(netif, groupaddr);
 
@@ -441,15 +482,13 @@ mld6_leavegroup(const ip6_addr_t *srcaddr, const ip6_addr_t *groupaddr)
       /* Decrement group use */
       group->use--;
     }
-        /* Leave on this interface */
+
-        err = ERR_OK;
+    /* Left group */
-      }
+    return ERR_OK;
-    }
-    /* proceed to next network interface */
-    netif = netif->next;
   }
 
-  return err;
+  /* Group not found */
+  return ERR_VAL;
 }
 
 

src/include/lwip/mld6.h

@@ -105,7 +105,9 @@ void   mld6_tmr(void);
 struct mld_group *mld6_lookfor_group(struct netif *ifp, const ip6_addr_t *addr);
 void   mld6_input(struct pbuf *p, struct netif *inp);
 err_t  mld6_joingroup(const ip6_addr_t *srcaddr, const ip6_addr_t *groupaddr);
+err_t  mld6_joingroup_netif(struct netif *netif, const ip6_addr_t *groupaddr);
 err_t  mld6_leavegroup(const ip6_addr_t *srcaddr, const ip6_addr_t *groupaddr);
+err_t  mld6_leavegroup_netif(struct netif *netif, const ip6_addr_t *groupaddr);
 
 
 #ifdef __cplusplus