npd: rework IPv6 relay logic (FS#396)
[project/odhcpd.git] / src / ndp.c
index 9fc539b..8824879 100644 (file)
--- a/src/ndp.c
+++ b/src/ndp.c
 
 #include <linux/rtnetlink.h>
 #include <linux/filter.h>
+
+#include <netlink/msg.h>
+#include <netlink/socket.h>
+#include <netlink/attr.h>
+
 #include "router.h"
+#include "dhcpv6.h"
 #include "ndp.h"
 
-
+struct event_socket {
+       struct odhcpd_event ev;
+       struct nl_sock *sock;
+};
 
 static void handle_solicit(void *addr, void *data, size_t len,
                struct interface *iface, void *dest);
-static void handle_rtnetlink(void *addr, void *data, size_t len,
-               struct interface *iface, void *dest);
-static ssize_t ping6(struct in6_addr *addr,
-               const struct interface *iface);
+static void handle_rtnl_event(struct odhcpd_event *ev);
+static int cb_rtnl_valid(struct nl_msg *msg, void *arg);
+static void catch_rtnetlink(int error);
 
-static uint32_t rtnl_seqid = 0;
 static int ping_socket = -1;
-static struct odhcpd_event rtnl_event = {{.fd = -1}, handle_rtnetlink};
-
+static struct event_socket rtnl_event = {
+       .ev = {
+               .uloop = {.fd = - 1, },
+               .handle_dgram = NULL,
+               .handle_error = catch_rtnetlink,
+               .recv_msgs = handle_rtnl_event,
+       },
+       .sock = NULL,
+};
 
 // Filter ICMPv6 messages of type neighbor soliciation
 static struct sock_filter bpf[] = {
@@ -61,29 +75,28 @@ static const struct sock_fprog bpf_prog = {sizeof(bpf) / sizeof(*bpf), bpf};
 // Initialize NDP-proxy
 int init_ndp(void)
 {
-       // Setup netlink socket
-       if ((rtnl_event.uloop.fd = odhcpd_open_rtnl()) < 0)
-               return -1;
-
-       // Receive netlink neighbor and ip-address events
-       uint32_t group = RTNLGRP_IPV6_IFADDR;
-       setsockopt(rtnl_event.uloop.fd, SOL_NETLINK,
-                       NETLINK_ADD_MEMBERSHIP, &group, sizeof(group));
-       group = RTNLGRP_IPV6_ROUTE;
-       setsockopt(rtnl_event.uloop.fd, SOL_NETLINK,
-                       NETLINK_ADD_MEMBERSHIP, &group, sizeof(group));
-
-       // Synthesize initial address events
-       struct {
-               struct nlmsghdr nh;
-               struct ifaddrmsg ifa;
-       } req2 = {
-               {sizeof(req2), RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP,
-                               ++rtnl_seqid, 0},
-               {.ifa_family = AF_INET6}
-       };
-       send(rtnl_event.uloop.fd, &req2, sizeof(req2), MSG_DONTWAIT);
-       odhcpd_register(&rtnl_event);
+       int val = 256 * 1024;
+
+       rtnl_event.sock = odhcpd_create_nl_socket(NETLINK_ROUTE);
+       if (!rtnl_event.sock)
+               goto err;
+
+       rtnl_event.ev.uloop.fd = nl_socket_get_fd(rtnl_event.sock);
+
+       if (nl_socket_set_buffer_size(rtnl_event.sock, val, 0))
+               goto err;
+
+       nl_socket_disable_seq_check(rtnl_event.sock);
+
+       nl_socket_modify_cb(rtnl_event.sock, NL_CB_VALID, NL_CB_CUSTOM,
+                       cb_rtnl_valid, NULL);
+
+       // Receive IPv6 address, IPv6 routes and neighbor events
+       if (nl_socket_add_memberships(rtnl_event.sock, RTNLGRP_IPV6_IFADDR,
+                               RTNLGRP_IPV6_ROUTE, RTNLGRP_NEIGH, 0))
+               goto err;
+
+       odhcpd_register(&rtnl_event.ev);
 
        // Open ICMPv6 socket
        ping_socket = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
@@ -92,7 +105,7 @@ int init_ndp(void)
                        return -1;
        }
 
-       int val = 2;
+       val = 2;
        setsockopt(ping_socket, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
 
        // This is required by RFC 4861
@@ -105,28 +118,54 @@ int init_ndp(void)
        ICMP6_FILTER_SETBLOCKALL(&filt);
        setsockopt(ping_socket, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
 
+       return 0;
 
-       // Netlink socket, continued...
-       group = RTNLGRP_NEIGH;
-       setsockopt(rtnl_event.uloop.fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &group, sizeof(group));
+err:
+       if (rtnl_event.sock) {
+               nl_socket_free(rtnl_event.sock);
+               rtnl_event.sock = NULL;
+               rtnl_event.ev.uloop.fd = -1;
+       }
 
-       return 0;
+       return -1;
 }
 
-
-static void dump_neigh_table(bool proxy)
+static void dump_neigh_table(const bool proxy)
 {
-       struct {
-               struct nlmsghdr nh;
-               struct ndmsg ndm;
-       } req = {
-               {sizeof(req), RTM_GETNEIGH, NLM_F_REQUEST | NLM_F_DUMP,
-                               ++rtnl_seqid, 0},
-               {.ndm_family = AF_INET6, .ndm_flags = (proxy) ? NTF_PROXY : 0}
+       struct nl_msg *msg;
+       struct ndmsg ndm = {
+               .ndm_family = AF_INET6,
+               .ndm_flags = proxy ? NTF_PROXY : 0,
        };
-       send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
+
+       msg = nlmsg_alloc_simple(RTM_GETNEIGH, NLM_F_REQUEST | NLM_F_DUMP);
+       if (!msg)
+               return;
+
+       nlmsg_append(msg, &ndm, sizeof(ndm), 0);
+
+       nl_send_auto_complete(rtnl_event.sock, msg);
+
+       nlmsg_free(msg);
 }
 
+static void dump_addr_table(void)
+{
+       struct nl_msg *msg;
+       struct ifaddrmsg ifa = {
+               .ifa_family = AF_INET6,
+       };
+
+       msg = nlmsg_alloc_simple(RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP);
+       if (!msg)
+               return;
+
+       nlmsg_append(msg, &ifa, sizeof(ifa), 0);
+
+       nl_send_auto_complete(rtnl_event.sock, msg);
+
+       nlmsg_free(msg);
+}
 
 int setup_ndp_interface(struct interface *iface, bool enable)
 {
@@ -135,17 +174,24 @@ int setup_ndp_interface(struct interface *iface, bool enable)
        int procfd = open(procbuf, O_WRONLY);
        bool dump_neigh = false;
 
-       if (iface->ndp_event.uloop.fd >= 0) {
+       if (iface->ndp_event.uloop.fd > 0) {
                uloop_fd_delete(&iface->ndp_event.uloop);
                close(iface->ndp_event.uloop.fd);
                iface->ndp_event.uloop.fd = -1;
 
-               write(procfd, "0\n", 2);
+               if (!enable || iface->ndp != RELAYD_RELAY)
+                       if (write(procfd, "0\n", 2) < 0) {}
+
                dump_neigh = true;
        }
 
+       if (enable && (iface->ra == RELAYD_SERVER ||
+                       iface->dhcpv6 == RELAYD_SERVER || iface->ndp == RELAYD_RELAY))
+               dump_addr_table();
+
        if (enable && iface->ndp == RELAYD_RELAY) {
-               write(procfd, "1\n", 2);
+               if (write(procfd, "1\n", 2) < 0) {}
+               close(procfd);
 
                int sock = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC, htons(ETH_P_IPV6));
                if (sock < 0) {
@@ -188,8 +234,8 @@ int setup_ndp_interface(struct interface *iface, bool enable)
                        dump_neigh_table(false);
                else
                        dump_neigh = false;
-       }
-       close(procfd);
+       } else
+               close(procfd);
 
        if (dump_neigh)
                dump_neigh_table(true);
@@ -200,17 +246,16 @@ int setup_ndp_interface(struct interface *iface, bool enable)
 
 // Send an ICMP-ECHO. This is less for actually pinging but for the
 // neighbor cache to be kept up-to-date.
-static ssize_t ping6(struct in6_addr *addr,
+static void ping6(struct in6_addr *addr,
                const struct interface *iface)
 {
-       struct sockaddr_in6 dest = {AF_INET6, 0, 0, *addr, 0};
-       struct icmp6_hdr echo = {.icmp6_type = ICMP6_ECHO_REQUEST};
-       struct iovec iov = {&echo, sizeof(echo)};
-
-       // Linux seems to not honor IPV6_PKTINFO on raw-sockets, so work around
-       setsockopt(ping_socket, SOL_SOCKET, SO_BINDTODEVICE,
-                       iface->ifname, sizeof(iface->ifname));
-       return odhcpd_send(ping_socket, &dest, &iov, 1, iface);
+       struct sockaddr_in6 dest = { .sin6_family = AF_INET6, .sin6_addr = *addr, .sin6_scope_id = iface->ifindex, };
+       struct icmp6_hdr echo = { .icmp6_type = ICMP6_ECHO_REQUEST };
+       struct iovec iov = { .iov_base = &echo, .iov_len = sizeof(echo) };
+
+       odhcpd_setup_route(addr, 128, iface, NULL, 128, true);
+       odhcpd_send(ping_socket, &dest, &iov, 1, iface);
+       odhcpd_setup_route(addr, 128, iface, NULL, 128, false);
 }
 
 
@@ -225,9 +270,10 @@ static void handle_solicit(void *addr, void *data, size_t len,
        // Solicitation is for duplicate address detection
        bool ns_is_dad = IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src);
 
+       // Don't process solicit messages on non relay interfaces
        // Don't forward any non-DAD solicitation for external ifaces
        // TODO: check if we should even forward DADs for them
-       if (iface->external && !ns_is_dad)
+       if (iface->ndp != RELAYD_RELAY || (iface->external && !ns_is_dad))
                return;
 
        if (len < sizeof(*ip6) + sizeof(*req))
@@ -249,232 +295,235 @@ static void handle_solicit(void *addr, void *data, size_t len,
 
        struct interface *c;
        list_for_each_entry(c, &interfaces, head)
-               if (iface->ndp == RELAYD_RELAY && iface != c &&
-                               (!ns_is_dad || !c->external == false))
+               if (iface != c && c->ndp == RELAYD_RELAY &&
+                               (ns_is_dad || !c->external))
                        ping6(&req->nd_ns_target, c);
 }
 
+// Use rtnetlink to modify kernel routes
+static void setup_route(struct in6_addr *addr, struct interface *iface, bool add)
+{
+       char namebuf[INET6_ADDRSTRLEN];
+       inet_ntop(AF_INET6, addr, namebuf, sizeof(namebuf));
+       syslog(LOG_NOTICE, "%s about %s on %s",
+                       (add) ? "Learned" : "Forgot", namebuf, iface->ifname);
 
-void odhcpd_setup_route(const struct in6_addr *addr, int prefixlen,
-               const struct interface *iface, const struct in6_addr *gw, bool add)
+       if (iface->learn_routes)
+               odhcpd_setup_route(addr, 128, iface, NULL, 1024, add);
+}
+
+// compare prefixes
+static int prefixcmp(const void *va, const void *vb)
 {
-       struct req {
-               struct nlmsghdr nh;
-               struct rtmsg rtm;
-               struct rtattr rta_dst;
-               struct in6_addr dst_addr;
-               struct rtattr rta_oif;
-               uint32_t ifindex;
-               struct rtattr rta_table;
-               uint32_t table;
-               struct rtattr rta_gw;
-               struct in6_addr gw;
-       } req = {
-               {sizeof(req), 0, NLM_F_REQUEST, ++rtnl_seqid, 0},
-               {AF_INET6, prefixlen, 0, 0, 0, 0, 0, 0, 0},
-               {sizeof(struct rtattr) + sizeof(struct in6_addr), RTA_DST},
-               *addr,
-               {sizeof(struct rtattr) + sizeof(uint32_t), RTA_OIF},
-               iface->ifindex,
-               {sizeof(struct rtattr) + sizeof(uint32_t), RTA_TABLE},
-               RT_TABLE_MAIN,
-               {sizeof(struct rtattr) + sizeof(struct in6_addr), RTA_GATEWAY},
-               IN6ADDR_ANY_INIT,
-       };
+       const struct odhcpd_ipaddr *a = va, *b = vb;
+       uint32_t a_pref = ((a->addr.s6_addr[0] & 0xfe) != 0xfc) ? a->preferred : 1;
+       uint32_t b_pref = ((b->addr.s6_addr[0] & 0xfe) != 0xfc) ? b->preferred : 1;
+       return (a_pref < b_pref) ? 1 : (a_pref > b_pref) ? -1 : 0;
+}
+
+// Check address update
+static void check_addr_updates(struct interface *iface)
+{
+       struct odhcpd_ipaddr addr[RELAYD_MAX_ADDRS] = {{IN6ADDR_ANY_INIT, 0, 0, 0, 0}};
+       time_t now = odhcpd_time();
+       ssize_t len = odhcpd_get_interface_addresses(iface->ifindex, addr, ARRAY_SIZE(addr));
+
+       if (len < 0)
+               return;
 
-       if (gw)
-               req.gw = *gw;
-
-       if (add) {
-               req.nh.nlmsg_type = RTM_NEWROUTE;
-               req.nh.nlmsg_flags |= (NLM_F_CREATE | NLM_F_REPLACE);
-               req.rtm.rtm_protocol = RTPROT_BOOT;
-               req.rtm.rtm_scope = (gw) ? RT_SCOPE_UNIVERSE : RT_SCOPE_LINK;
-               req.rtm.rtm_type = RTN_UNICAST;
-       } else {
-               req.nh.nlmsg_type = RTM_DELROUTE;
-               req.rtm.rtm_scope = RT_SCOPE_NOWHERE;
+       qsort(addr, len, sizeof(*addr), prefixcmp);
+
+       for (int i = 0; i < len; ++i) {
+               addr[i].addr.s6_addr32[3] = 0;
+
+               if (addr[i].preferred < UINT32_MAX - now)
+                       addr[i].preferred += now;
+
+               if (addr[i].valid < UINT32_MAX - now)
+                       addr[i].valid += now;
        }
 
-       size_t reqlen = (gw) ? sizeof(req) : offsetof(struct req, rta_gw);
-       send(rtnl_event.uloop.fd, &req, reqlen, MSG_DONTWAIT);
+       bool change = len != (ssize_t)iface->ia_addr_len;
+       for (ssize_t i = 0; !change && i < len; ++i)
+               if (!IN6_ARE_ADDR_EQUAL(&addr[i].addr, &iface->ia_addr[i].addr) ||
+                               (addr[i].preferred > 0) != (iface->ia_addr[i].preferred > 0) ||
+                               addr[i].valid < iface->ia_addr[i].valid ||
+                               addr[i].preferred < iface->ia_addr[i].preferred)
+                       change = true;
+
+       if (change)
+               dhcpv6_ia_preupdate(iface);
+
+       memcpy(iface->ia_addr, addr, len * sizeof(*addr));
+       iface->ia_addr_len = len;
+
+       if (change)
+               dhcpv6_ia_postupdate(iface, now);
+
+       if (change) {
+               syslog(LOG_INFO, "Raising SIGUSR1 due to address change on %s", iface->ifname);
+               raise(SIGUSR1);
+       }
 }
 
-// Use rtnetlink to modify kernel routes
-static void setup_route(struct in6_addr *addr, struct interface *iface,
-               bool add)
+void setup_addr_for_relaying(struct in6_addr *addr, struct interface *iface, bool add)
 {
-       char namebuf[INET6_ADDRSTRLEN];
-       inet_ntop(AF_INET6, addr, namebuf, sizeof(namebuf));
-       syslog(LOG_NOTICE, "%s about %s on %s", (add) ? "Learned" : "Forgot",
-                       namebuf, (iface) ? iface->ifname : "<pending>");
+       struct interface *c;
 
-       if (!iface || !iface->learn_routes)
-               return;
+       list_for_each_entry(c, &interfaces, head) {
+               if (iface == c || (c->ndp != RELAYD_RELAY && !add))
+                       continue;
 
-       odhcpd_setup_route(addr, 128, iface, NULL, add);
+               odhcpd_setup_proxy_neigh(addr, c, c->ndp == RELAYD_RELAY ? add : false);
+       }
+}
+
+void setup_ping6(struct in6_addr *addr, struct interface *iface)
+{
+       struct interface *c;
+
+       list_for_each_entry(c, &interfaces, head) {
+               if (iface == c || c->ndp != RELAYD_RELAY ||
+                               c->external == true)
+                       continue;
+
+               ping6(addr, c);
+       }
+}
+
+static struct in6_addr last_solicited;
+
+static void handle_rtnl_event(struct odhcpd_event *e)
+{
+       struct event_socket *ev_sock = container_of(e, struct event_socket, ev);
+
+       nl_recvmsgs_default(ev_sock->sock);
 }
 
 
 // Handler for neighbor cache entries from the kernel. This is our source
 // to learn and unlearn hosts on interfaces.
-static void handle_rtnetlink(_unused void *addr, void *data, size_t len,
-               _unused struct interface *iface, _unused void *dest)
+static int cb_rtnl_valid(struct nl_msg *msg, _unused void *arg)
 {
-       bool dump_neigh = false;
-       struct in6_addr last_solicited = IN6ADDR_ANY_INIT;
-
-       for (struct nlmsghdr *nh = data; NLMSG_OK(nh, len);
-                       nh = NLMSG_NEXT(nh, len)) {
-               struct rtmsg *rtm = NLMSG_DATA(nh);
-               if ((nh->nlmsg_type == RTM_NEWROUTE ||
-                               nh->nlmsg_type == RTM_DELROUTE) &&
-                               rtm->rtm_dst_len == 0)
-                       raise(SIGUSR1); // Inform about a change in default route
-
-               struct ndmsg *ndm = NLMSG_DATA(nh);
-               struct ifaddrmsg *ifa = NLMSG_DATA(nh);
-               if (nh->nlmsg_type != RTM_NEWNEIGH
-                               && nh->nlmsg_type != RTM_DELNEIGH
-                               && nh->nlmsg_type != RTM_NEWADDR
-                               && nh->nlmsg_type != RTM_DELADDR)
-                       continue; // Unrelated message type
-               bool is_addr = (nh->nlmsg_type == RTM_NEWADDR
-                               || nh->nlmsg_type == RTM_DELADDR);
-
-               // Family and ifindex are on the same offset for NEIGH and ADDR
-               if (NLMSG_PAYLOAD(nh, 0) < sizeof(*ndm)
-                               || ndm->ndm_family != AF_INET6)
-                       continue; //
-
-               // Lookup interface
-               struct interface *iface;
-               if (!(iface = odhcpd_get_interface_by_index(ndm->ndm_ifindex)))
-                       continue;
+       struct nlmsghdr *hdr = nlmsg_hdr(msg);
+       struct in6_addr *addr = NULL;
+       struct interface *iface = NULL;
+       bool add = false;
+
+       switch (hdr->nlmsg_type) {
+       case RTM_NEWROUTE:
+       case RTM_DELROUTE: {
+               struct rtmsg *rtm = nlmsg_data(hdr);
+
+               if (!nlmsg_valid_hdr(hdr, sizeof(*rtm)) ||
+                               rtm->rtm_family != AF_INET6)
+                       return NL_SKIP;
+
+               if (rtm->rtm_dst_len == 0) {
+                       syslog(LOG_INFO, "Raising SIGUSR1 due to default route change");
+                       raise(SIGUSR1);
+               }
+               return NL_OK;
+       }
+
+       case RTM_NEWADDR:
+               add = true;
+       case RTM_DELADDR: {
+               struct ifaddrmsg *ifa = nlmsg_data(hdr);
+               struct nlattr *nla[__IFA_MAX];
 
-               // Data to retrieve
-               size_t rta_offset = (is_addr) ? sizeof(*ifa) : sizeof(*ndm);
-               uint16_t atype = (is_addr) ? IFA_ADDRESS : NDA_DST;
-               ssize_t alen = NLMSG_PAYLOAD(nh, rta_offset);
-               struct in6_addr *addr = NULL;
+               if (!nlmsg_valid_hdr(hdr, sizeof(*ifa)) ||
+                               ifa->ifa_family != AF_INET6)
+                       return NL_SKIP;
 
-               for (struct rtattr *rta = (void*)(((uint8_t*)ndm) + rta_offset);
-                               RTA_OK(rta, alen); rta = RTA_NEXT(rta, alen))
-                       if (rta->rta_type == atype &&
-                                       RTA_PAYLOAD(rta) >= sizeof(*addr))
-                               addr = RTA_DATA(rta);
+               iface = odhcpd_get_interface_by_index(ifa->ifa_index);
+               if (!iface)
+                       return NL_SKIP;
 
-               // Address not specified or unrelated
+               nlmsg_parse(hdr, sizeof(*ifa), nla, __IFA_MAX - 1, NULL);
+               if (!nla[IFA_ADDRESS])
+                       return NL_SKIP;
+
+               addr = nla_data(nla[IFA_ADDRESS]);
                if (!addr || IN6_IS_ADDR_LINKLOCAL(addr) ||
                                IN6_IS_ADDR_MULTICAST(addr))
-                       continue;
+                       return NL_SKIP;
 
-               // Check for states
-               bool add;
-               if (is_addr)
-                       add = (nh->nlmsg_type == RTM_NEWADDR);
-               else
-                       add = (nh->nlmsg_type == RTM_NEWNEIGH && (ndm->ndm_state &
-                               (NUD_REACHABLE | NUD_STALE | NUD_DELAY | NUD_PROBE
-                                               | NUD_PERMANENT | NUD_NOARP)));
-
-               if (iface->ndp == RELAYD_RELAY) {
-                       // Replay change to all neighbor cache
-                       struct {
-                               struct nlmsghdr nh;
-                               struct ndmsg ndm;
-                               struct nlattr nla_dst;
-                               struct in6_addr dst;
-                       } req = {
-                               {sizeof(req), RTM_DELNEIGH, NLM_F_REQUEST,
-                                               ++rtnl_seqid, 0},
-                               {.ndm_family = AF_INET6, .ndm_flags = NTF_PROXY},
-                               {sizeof(struct nlattr) + sizeof(struct in6_addr), NDA_DST},
-                               *addr
-                       };
-
-                       if (ndm->ndm_flags & NTF_PROXY) {
-                               // Dump & flush proxy entries
-                               if (nh->nlmsg_type == RTM_NEWNEIGH) {
-                                       req.ndm.ndm_ifindex = iface->ifindex;
-                                       send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
-                                       dump_neigh = true;
-                               }
-                       } else if (add) {
-                               struct interface *c;
-                               list_for_each_entry(c, &interfaces, head) {
-                                       if (iface == c)
-                                               continue;
-
-                                       if (c->ndp == RELAYD_RELAY) {
-                                               req.nh.nlmsg_type = RTM_NEWNEIGH;
-                                               req.nh.nlmsg_flags |= NLM_F_CREATE | NLM_F_REPLACE;
-
-                                               req.ndm.ndm_ifindex = c->ifindex;
-                                               send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
-                                       } else { // Delete NDP cache from interfaces without relay
-                                               req.nh.nlmsg_type = RTM_DELNEIGH;
-                                               req.nh.nlmsg_flags &= ~(NLM_F_CREATE | NLM_F_REPLACE);
-
-                                               req.ndm.ndm_ifindex = c->ifindex;
-                                               send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
-                                       }
-                               }
-
-                               setup_route(addr, iface, true);
-                       } else {
-                               if (nh->nlmsg_type == RTM_NEWNEIGH) {
-                                       // might be locally originating
-                                       if (!IN6_ARE_ADDR_EQUAL(&last_solicited, addr)) {
-                                               last_solicited = *addr;
-
-                                               struct interface *c;
-                                               list_for_each_entry(c, &interfaces, head)
-                                                       if (iface->ndp == RELAYD_RELAY && iface != c &&
-                                                                       !c->external == false)
-                                                               ping6(addr, c);
-                                       }
-                               } else {
-                                       struct interface *c;
-                                       list_for_each_entry(c, &interfaces, head) {
-                                               if (c->ndp == RELAYD_RELAY && iface != c) {
-                                                       req.ndm.ndm_ifindex = c->ifindex;
-                                                       send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
-                                               }
-                                       }
-                                       setup_route(addr, iface, false);
-
-                                       // also: dump to add proxies back in case it moved elsewhere
-                                       dump_neigh = true;
-                               }
-                       }
-               }
+               check_addr_updates(iface);
 
-               if (is_addr) {
-                       if (iface->ra == RELAYD_SERVER)
-                               raise(SIGUSR1); // Inform about a change in addresses
+               if (iface->ndp != RELAYD_RELAY)
+                       break;
 
-                       if (iface->dhcpv6 == RELAYD_SERVER)
-                               iface->ia_reconf = true;
+               /* handle the relay logic below */
+               setup_addr_for_relaying(addr, iface, add);
 
-                       if (iface->ndp == RELAYD_RELAY && iface->master) {
-                               // Replay address changes on all slave interfaces
-                               nh->nlmsg_flags = NLM_F_REQUEST;
+               if (!add)
+                       dump_neigh_table(false);
+               break;
+       }
+
+       case RTM_NEWNEIGH:
+               add = true;
+       case RTM_DELNEIGH: {
+               struct ndmsg *ndm = nlmsg_data(hdr);
+               struct nlattr *nla[__NDA_MAX];
+
+               if (!nlmsg_valid_hdr(hdr, sizeof(*ndm)) ||
+                               ndm->ndm_family != AF_INET6)
+                       return NL_SKIP;
+
+               iface = odhcpd_get_interface_by_index(ndm->ndm_ifindex);
+               if (!iface || iface->ndp != RELAYD_RELAY)
+                       return (iface ? NL_OK : NL_SKIP);
+
+               nlmsg_parse(hdr, sizeof(*ndm), nla, __NDA_MAX - 1, NULL);
+               if (!nla[NDA_DST])
+                       return NL_SKIP;
+
+               addr = nla_data(nla[NDA_DST]);
+               if (!addr || IN6_IS_ADDR_LINKLOCAL(addr) ||
+                               IN6_IS_ADDR_MULTICAST(addr))
+                       return NL_SKIP;
+
+               if (ndm->ndm_flags & NTF_PROXY) {
+                       /* Dump and flush proxy entries */
+                       if (hdr->nlmsg_type == RTM_NEWNEIGH) {
+                               odhcpd_setup_proxy_neigh(addr, iface, false);
+                               setup_route(addr, iface, false);
+                               dump_neigh_table(false);
+                       }
 
-                               if (nh->nlmsg_type == RTM_NEWADDR)
-                                       nh->nlmsg_flags |= NLM_F_CREATE | NLM_F_REPLACE;
+                       return NL_OK;
+               }
 
-                               struct interface *c;
-                               list_for_each_entry(c, &interfaces, head) {
-                                       if (c->ndp == RELAYD_RELAY && !c->master) {
-                                               ifa->ifa_index = c->ifindex;
-                                               send(rtnl_event.uloop.fd, nh, nh->nlmsg_len, MSG_DONTWAIT);
-                                       }
-                               }
+               if (add && !(ndm->ndm_state &
+                               (NUD_REACHABLE | NUD_STALE | NUD_DELAY | NUD_PROBE |
+                                NUD_PERMANENT | NUD_NOARP))) {
+                       if (!IN6_ARE_ADDR_EQUAL(&last_solicited, addr)) {
+                               last_solicited = *addr;
+                               setup_ping6(addr, iface);
                        }
+
+                       return NL_OK;
                }
+
+               setup_addr_for_relaying(addr, iface, add);
+               setup_route(addr, iface, add);
+
+               if (!add)
+                       dump_neigh_table(false);
+               break;
        }
 
-       if (dump_neigh)
-               dump_neigh_table(false);
+       default:
+               return NL_SKIP;
+       }
+
+       return NL_OK;
+}
+
+static void catch_rtnetlink(int error)
+{
+       if (error == ENOBUFS)
+               dump_addr_table();
 }