Call unmapv4 only when it is necessary

Signed-off-by: Adrien Gallouët <adrien@gallouet.fr>

mud.c

@@ -654,14 +654,13 @@ mud_ss_from_sa(struct sockaddr_storage *ss, struct sockaddr *sa)
         break;
     case AF_INET6:
         memcpy(ss, sa, sizeof(struct sockaddr_in6));
+        mud_unmapv4(ss);
         break;
     default:
         errno = EINVAL;
         return -1;
     }
 
-    mud_unmapv4(ss);
-
     return 0;
 }
 
@@ -1093,10 +1092,9 @@ mud_localaddr(struct sockaddr_storage *addr, struct msghdr *msg)
         memcpy(&((struct sockaddr_in6 *)addr)->sin6_addr,
                &((struct in6_pktinfo *)CMSG_DATA(cmsg))->ipi6_addr,
                sizeof(struct in6_addr));
+        mud_unmapv4(addr);
     }
 
-    mud_unmapv4(addr);
-
     return 0;
 }