Install missing scope identifier for IPv6 link-local addresses

RTM_PROPOSAL's list of IP addresses does not contain scope IDs by design.
This is not a problem as the proposal is always bound to an interface,
as long as we use it...

Fill in the scope ID for link-local IPs and replace inet_ntop(3) usage with
getnameinfo(3) in the IPv6 case such that it actually turns up in the string
representation.

Otherwise resolv.conf(5) ends up with "nameserver fe80::1" entries and
libc/asr won't be able to resolve without an interface.

diff --git a/sbin/resolvd/resolvd.c b/sbin/resolvd/resolvd.c
index 6d04730..cbc7ff6 100644 (file)
--- a/sbin/resolvd/resolvd.c
+++ b/sbin/resolvd/resolvd.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: resolvd.c,v 1.19 2021/08/31 09:56:12 deraadt Exp $    */
+/*     $OpenBSD: resolvd.c,v 1.20 2021/11/13 17:32:46 kn Exp $ */
 /*
  * Copyright (c) 2021 Florian Obser <florian@openbsd.org>
  * Copyright (c) 2021 Theo de Raadt <deraadt@openbsd.org>
@@ -23,6 +23,7 @@
 #include <sys/syslog.h>
 #include <sys/time.h>
 #include <sys/un.h>
+#include <netdb.h>
 
 #include <arpa/inet.h>
 #include <netinet/in.h>
@@ -469,7 +470,8 @@ handle_route_message(struct rt_msghdr *rtm, struct sockaddr **rti_info)
                /* Add the new proposals */
                for (i = 0; i < rdns_count; i++) {
                        struct in_addr addr4;
-                       struct in6_addr addr6;
+                       struct sockaddr_in6 sin6;
+                       struct sockaddr *sa;
                        int new;
 
                        switch (af) {
@@ -486,16 +488,23 @@ handle_route_message(struct rt_msghdr *rtm, struct sockaddr **rti_info)
                                        lwarn("inet_ntop");
                                break;
                        case AF_INET6:
-                               memcpy(&addr6, src, sizeof(struct in6_addr));
+                               memset(&sin6, 0, sizeof(sin6));
+                               sin6.sin6_family = af;
+                               memcpy(&sin6.sin6_addr, src,
+                                   sizeof(struct in6_addr));
                                src += sizeof(struct in6_addr);
+                               if (IN6_IS_ADDR_LINKLOCAL(&sin6.sin6_addr))
+                                       sin6.sin6_scope_id = rtm->rtm_index;
                                new = findslot(learning);
-                               if (inet_ntop(af, &addr6, learning[new].ip,
-                                   INET6_ADDRSTRLEN) != NULL) {
+                               sa = (struct sockaddr *)(&sin6);
+                               if (getnameinfo(sa, sa->sa_len,
+                                   learning[new].ip, sizeof(learning[new].ip),
+                                   NULL, 0, NI_NUMERICHOST) == 0) {
                                        learning[new].prio = rtm->rtm_priority;
                                        learning[new].if_index = rtm->rtm_index;
                                        learning[new].af = af;
                                } else
-                                       lwarn("inet_ntop");
+                                       lwarn("getnameinfo");
                                break;
                        }
                }