socket: Fix IPv6 scope id lookup logic to handle another network device problem
The lookup logic preferred to return the last suitable scope id match.
This became a problem if there was already a suitable scope id match before
that was higher in the interface list. This now chooses the higher last
scope id interface match and thus probably in the routing preference.
diff --git a/common/socket.c b/common/socket.c
index 86cbf48..fd89c56 100644
--- a/common/socket.c
+++ b/common/socket.c
@@ -426,11 +426,16 @@
/* use if address is equal */
if (memcmp(&addr->sin6_addr.s6_addr, &addr_in->sin6_addr.s6_addr, sizeof(addr_in->sin6_addr.s6_addr)) == 0) {
- res = addr_in->sin6_scope_id;
/* if scope id equals the requested one then assume it was valid */
if (addr->sin6_scope_id == addr_in->sin6_scope_id) {
+ res = addr_in->sin6_scope_id;
break;
} else {
+ if ((addr_in->sin6_scope_id > addr->sin6_scope_id) && (res >= 0)) {
+ // use last valid scope id as we're past the requested scope id
+ break;
+ }
+ res = addr_in->sin6_scope_id;
continue;
}
}
@@ -440,11 +445,16 @@
continue;
}
- /* set the scope id of this interface as most likely candidate */
+ if ((addr_in->sin6_scope_id > addr->sin6_scope_id) && (res >= 0)) {
+ // use last valid scope id as we're past the requested scope id
+ break;
+ }
+
res = addr_in->sin6_scope_id;
/* if scope id equals the requested one then assume it was valid */
if (addr->sin6_scope_id == addr_in->sin6_scope_id) {
+ /* set the scope id of this interface as most likely candidate */
break;
}
}
