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.

diff --git a/sbin/dhcp6leased/engine.c b/sbin/dhcp6leased/engine.c
index e708f8e..5ab0754 100644 (file)
--- 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)