Track configured and new prefix delegations in iface.

When the DHCPv6 server renumbers and hands us new delegations we have
to deconfigure the old prefixes. To prevent situations where we have
no IPv6 at all, first configure the new prefixes and then remove the
old prefixes.

1 files changed, 46 insertions, 17 deletions

diff --git a/sbin/dhcp6leased/engine.c b/sbin/dhcp6leased/engine.c
index e708f8ea1fd..5ab07541653 100644
--- a/sbin/dhcp6leased/engine.c
+++ b/sbin/dhcp6leased/engine.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: engine.c,v 1.16 2024/07/09 16:15:42 florian Exp $	*/
+/*	$OpenBSD: engine.c,v 1.17 2024/07/09 16:24:57 florian Exp $	*/
 
 /*
  * Copyright (c) 2017, 2021, 2024 Florian Obser <florian@openbsd.org>
@@ -106,6 +106,7 @@ struct dhcp6leased_iface {
 	int				 serverid_len;
 	uint8_t				 serverid[SERVERID_SIZE];
 	struct prefix			 pds[MAX_IA];
+	struct prefix			 new_pds[MAX_IA];
 	struct timespec			 request_time;
 	struct timespec			 elapsed_time_start;
 	uint32_t			 lease_time;
@@ -134,6 +135,7 @@ void			 request_dhcp_discover(struct dhcp6leased_iface *);
 void			 request_dhcp_request(struct dhcp6leased_iface *);
 void			 configure_interfaces(struct dhcp6leased_iface *);
 void			 deconfigure_interfaces(struct dhcp6leased_iface *);
+int			 prefixcmp(struct prefix *, struct prefix *, int);
 void			 send_reconfigure_interface(struct iface_pd_conf *,
 			     struct prefix *, enum reconfigure_action);
 int			 engine_imsg_compose_main(int, pid_t, void *, uint16_t);
@@ -707,7 +709,6 @@ parse_dhcp(struct dhcp6leased_iface *iface, struct imsg_dhcp *dhcp)
 	struct dhcp_hdr		 hdr;
 	struct dhcp_option_hdr	 opt_hdr;
 	struct dhcp_iapd	 iapd;
-	struct prefix		 *pds = NULL;
 	size_t			 rem;
 	uint32_t		 t1, t2, lease_time;
 	int			 serverid_len, rapid_commit = 0;
@@ -731,11 +732,8 @@ parse_dhcp(struct dhcp6leased_iface *iface, struct imsg_dhcp *dhcp)
 	log_debug("%s: %s ia_count: %d", __func__, if_name,
 	    iface_conf->ia_count);
 
-	pds = calloc(iface_conf->ia_count, sizeof(struct prefix));
-	if (pds == NULL)
-		fatal("%s: calloc", __func__);
-
 	serverid_len = t1 = t2 = lease_time = 0;
+	memset(iface->new_pds, 0, sizeof(iface->new_pds));
 
 	p = dhcp->packet;
 	rem = dhcp->len;
@@ -819,7 +817,7 @@ parse_dhcp(struct dhcp6leased_iface *iface, struct imsg_dhcp *dhcp)
 				parse_ia_pd_options(p +
 				    sizeof(struct dhcp_iapd), opt_hdr.len -
 				    sizeof(struct dhcp_iapd),
-				    &pds[ntohl(iapd.iaid)]);
+				    &iface->new_pds[ntohl(iapd.iaid)]);
 			break;
 		case DHO_RAPID_COMMIT:
 			if (opt_hdr.len != 0) {
@@ -846,7 +844,7 @@ parse_dhcp(struct dhcp6leased_iface *iface, struct imsg_dhcp *dhcp)
 
 
 	SIMPLEQ_FOREACH(ia_conf, &iface_conf->iface_ia_list, entry) {
-		struct prefix	*pd = &pds[ia_conf->id];
+		struct prefix	*pd = &iface->new_pds[ia_conf->id];
 
 		if (pd->prefix_len == 0) {
 			log_warnx("%s: no IA for IAID %d found", __func__,
@@ -893,9 +891,7 @@ parse_dhcp(struct dhcp6leased_iface *iface, struct imsg_dhcp *dhcp)
 		}
 		iface->serverid_len = serverid_len;
 		memcpy(iface->serverid, serverid, SERVERID_SIZE);
-		memset(iface->pds, 0, sizeof(iface->pds));
-		memcpy(iface->pds, pds,
-		    iface_conf->ia_count * sizeof(struct prefix));
+		memcpy(iface->pds, iface->new_pds, sizeof(iface->pds));
 		state_transition(iface, IF_REQUESTING);
 		break;
 	case DHCPREPLY:
@@ -916,9 +912,7 @@ parse_dhcp(struct dhcp6leased_iface *iface, struct imsg_dhcp *dhcp)
 		}
 		iface->serverid_len = serverid_len;
 		memcpy(iface->serverid, serverid, SERVERID_SIZE);
-		memset(iface->pds, 0, sizeof(iface->pds));
-		memcpy(iface->pds, pds,
-		    iface_conf->ia_count * sizeof(struct prefix));
+
 		/* XXX handle t1 = 0 or t2 = 0 */
 		iface->t1 = t1;
 		iface->t2 = t2;
@@ -936,7 +930,7 @@ parse_dhcp(struct dhcp6leased_iface *iface, struct imsg_dhcp *dhcp)
 		break;
 	}
  out:
-	free(pds);
+	return;
 }
 
 void
@@ -1293,17 +1287,37 @@ configure_interfaces(struct dhcp6leased_iface *iface)
 
 	memset(&imsg_lease_info, 0, sizeof(imsg_lease_info));
 	imsg_lease_info.if_index = iface->if_index;
-	memcpy(imsg_lease_info.pds, iface->pds, sizeof(iface->pds));
+	memcpy(imsg_lease_info.pds, iface->new_pds, sizeof(iface->new_pds));
 	engine_imsg_compose_main(IMSG_WRITE_LEASE, 0, &imsg_lease_info,
 	    sizeof(imsg_lease_info));
 
 	SIMPLEQ_FOREACH(ia_conf, &iface_conf->iface_ia_list, entry) {
-		struct prefix	*pd = &iface->pds[ia_conf->id];
+		struct prefix	*pd = &iface->new_pds[ia_conf->id];
 
 		SIMPLEQ_FOREACH(pd_conf, &ia_conf->iface_pd_list, entry) {
 			send_reconfigure_interface(pd_conf, pd, CONFIGURE);
 		}
 	}
+
+	if (prefixcmp(iface->pds, iface->new_pds, iface_conf->ia_count) != 0) {
+		uint32_t	 i;
+		char		 ntopbuf[INET6_ADDRSTRLEN];
+
+		log_warnx("IA_PDs changed");
+		for (i = 0; i < iface_conf->ia_count; i++) {
+			log_debug("%s: iface->pds [%d]: %s/%d", __func__, i,
+			    inet_ntop(AF_INET6, &iface->pds[i].prefix, ntopbuf,
+			    INET6_ADDRSTRLEN), iface->pds[i].prefix_len);
+			log_debug("%s:        pds [%d]: %s/%d", __func__, i,
+			    inet_ntop(AF_INET6, &iface->new_pds[i].prefix,
+			    ntopbuf, INET6_ADDRSTRLEN),
+			    iface->new_pds[i].prefix_len);
+		}
+		deconfigure_interfaces(iface);
+	}
+
+	memcpy(iface->pds, iface->new_pds, sizeof(iface->pds));
+	memset(iface->new_pds, 0, sizeof(iface->new_pds));
 }
 
 void
@@ -1336,6 +1350,21 @@ deconfigure_interfaces(struct dhcp6leased_iface *iface)
 	}
 }
 
+int
+prefixcmp(struct prefix *a, struct prefix *b, int count)
+{
+	int i;
+
+	for (i = 0; i < count; i++) {
+		if (a[i].prefix_len != b[i].prefix_len)
+			return 1;
+		if (memcmp(&a[i].prefix, &b[i].prefix,
+		    sizeof(struct in6_addr)) != 0)
+			return 1;
+	}
+	return 0;
+}
+
 void
 send_reconfigure_interface(struct iface_pd_conf *pd_conf, struct prefix *pd,
     enum reconfigure_action action)