util: Add link-local check to net interface

Add a check for link-local IPv6 addresses to the net
interface to support better computation of network
pairings in the weighted reachable component.

Signed-off-by: Brian Barrett <bbarrett@amazon.com>

opal/util/net.c

@@ -358,6 +358,30 @@ opal_net_addr_isipv4public(const struct sockaddr *addr)
     return false;
 }
 
+bool
+opal_net_addr_isipv6linklocal(const struct sockaddr *addr)
+{
+    struct sockaddr_in6 if_addr;
+
+    switch (addr->sa_family) {
+#if OPAL_ENABLE_IPV6
+        case AF_INET6:
+            if_addr.sin6_family = AF_INET6;
+            if (1 != inet_pton(AF_INET6, "fe80::0000", &if_addr.sin6_addr)) {
+                return false;
+            }
+            return opal_net_samenetwork(addr, (struct sockaddr*)&if_addr, 64);
+#endif
+        case AF_INET:
+            return false;
+        default:
+            opal_output (0,
+                         "unhandled sa_family %d passed to opal_net_addr_isipv6linklocal\n",
+                         addr->sa_family);
+    }
+
+    return false;
+}
 
 char*
 opal_net_get_hostname(const struct sockaddr *addr)

opal/util/net.h

@@ -112,6 +112,14 @@ OPAL_DECLSPEC bool opal_net_samenetwork(const struct sockaddr *addr1,
  */
 OPAL_DECLSPEC bool opal_net_addr_isipv4public(const struct sockaddr *addr);
 
+/**
+ * Is the given address a link-local IPv6 address?  Returns false for IPv4
+ * address.
+ *
+ * @param addr      address as struct sockaddr
+ * @return          true, if \c addr is IPv6 link-local, false otherwise
+ */
+OPAL_DECLSPEC bool opal_net_addr_isipv6linklocal(const struct sockaddr *addr);
 
 /**
  * Get string version of address