sync hostfile more often
[project/odhcpd.git] / src / ndp.c
index c1ac063..44884be 100644 (file)
--- a/src/ndp.c
+++ b/src/ndp.c
@@ -17,7 +17,6 @@
 #include <signal.h>
 #include <errno.h>
 
-#include <fcntl.h>
 #include <unistd.h>
 #include <arpa/inet.h>
 #include <sys/socket.h>
@@ -37,11 +36,18 @@ 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 struct ndp_neighbor* find_neighbor(struct in6_addr *addr, bool strict);
+static void modify_neighbor(struct in6_addr *addr, struct interface *iface,
+               bool add);
 static ssize_t ping6(struct in6_addr *addr,
                const struct interface *iface);
 
+static struct list_head neighbors = LIST_HEAD_INIT(neighbors);
+static size_t neighbor_count = 0;
 static uint32_t rtnl_seqid = 0;
+
 static int ping_socket = -1;
+static struct odhcpd_event ndp_event = {{.fd = -1}, handle_solicit};
 static struct odhcpd_event rtnl_event = {{.fd = -1}, handle_rtnetlink};
 
 
@@ -110,85 +116,105 @@ int init_ndp(void)
        group = RTNLGRP_NEIGH;
        setsockopt(rtnl_event.uloop.fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &group, sizeof(group));
 
-       return 0;
-}
-
-
-static void dump_neigh_table(bool proxy)
-{
+       // Synthesize initial neighbor events
        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}
+               {.ndm_family = AF_INET6}
        };
        send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
+
+       return 0;
 }
 
 
 int setup_ndp_interface(struct interface *iface, bool enable)
 {
-       char procbuf[64];
-       snprintf(procbuf, sizeof(procbuf), "/proc/sys/net/ipv6/conf/%s/proxy_ndp", iface->ifname);
-       int procfd = open(procbuf, O_WRONLY);
-       bool dump_neigh = false;
-
-       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);
-               dump_neigh = true;
-       }
+       struct packet_mreq mreq = {iface->ifindex, PACKET_MR_ALLMULTI, ETH_ALEN, {0}};
+       setsockopt(ndp_event.uloop.fd, SOL_PACKET, PACKET_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
+
+       struct ndp_neighbor *c, *n;
+       list_for_each_entry_safe(c, n, &neighbors, head)
+               if (c->iface == iface && (c->timeout == 0 || iface->ndp != RELAYD_RELAY || !enable))
+                       modify_neighbor(&c->addr, c->iface, false);
 
        if (enable && iface->ndp == RELAYD_RELAY) {
-               write(procfd, "1\n", 2);
+               setsockopt(ndp_event.uloop.fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
+
+               if (iface->static_ndp_len) {
+                       char *entry = alloca(iface->static_ndp_len), *saveptr;
+                       if (!entry) {
+                               syslog(LOG_ERR, "Alloca failed for static NDP list");
+                               return -1;
+                       }
+                       memcpy(entry, iface->static_ndp, iface->static_ndp_len);
+
+                       for (entry = strtok_r(entry, " ", &saveptr); entry; entry = strtok_r(NULL, " ", &saveptr)) {
+                               char *sep;
+                               struct ndp_neighbor *n = malloc(sizeof(*n));
+                               if (!n) {
+                                       syslog(LOG_ERR, "Malloc failed for static NDP-prefix %s", entry);
+                                       return -1;
+                               }
+
+                               n->iface = iface;
+                               n->timeout = 0;
 
-               int sock = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC, htons(ETH_P_IPV6));
+                               sep = strchr(entry, '/');
+                               if (!sep) {
+                                       free(n);
+                                       syslog(LOG_ERR, "Invalid static NDP-prefix %s", entry);
+                                       return -1;
+                               }
+                               
+                               *sep = 0;
+                               n->len = atoi(sep + 1);
+                               if (inet_pton(AF_INET6, entry, &n->addr) != 1 || n->len > 128) {
+                                       free(n);
+                                       syslog(LOG_ERR, "Invalid static NDP-prefix %s/%s", entry, sep + 1);
+                                       return -1;
+                               }
+
+                               list_add(&n->head, &neighbors);
+                       }
+               }
+       }
+
+       bool enable_packet = false;
+       struct interface *i;
+       list_for_each_entry(i, &interfaces, head) {
+               if (i == iface && !enable)
+                       continue;
+
+               if (i->ndp == RELAYD_RELAY)
+                       enable_packet = true;
+       }
+
+       if (enable_packet && ndp_event.uloop.fd < 0) {
+               // Create socket for intercepting NDP
+               int sock = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
+                               htons(ETH_P_ALL)); // ETH_P_ALL for ingress + egress
                if (sock < 0) {
                        syslog(LOG_ERR, "Unable to open packet socket: %s",
                                        strerror(errno));
                        return -1;
                }
 
-#ifdef PACKET_RECV_TYPE
-               int pktt = 1 << PACKET_MULTICAST;
-               setsockopt(sock, SOL_PACKET, PACKET_RECV_TYPE, &pktt, sizeof(pktt));
-#endif
-
                if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_FILTER,
                                &bpf_prog, sizeof(bpf_prog))) {
                        syslog(LOG_ERR, "Failed to set BPF: %s", strerror(errno));
                        return -1;
                }
 
-               struct sockaddr_ll ll = {
-                       .sll_family = AF_PACKET,
-                       .sll_ifindex = iface->ifindex,
-                       .sll_protocol = htons(ETH_P_IPV6),
-               };
-               bind(sock, (struct sockaddr*)&ll, sizeof(ll));
-
-               struct packet_mreq mreq = {iface->ifindex, PACKET_MR_ALLMULTI, ETH_ALEN, {0}};
-               setsockopt(sock, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
-
-               iface->ndp_event.uloop.fd = sock;
-               iface->ndp_event.handle_dgram = handle_solicit;
-               odhcpd_register(&iface->ndp_event);
-
-               // If we already were enabled dump is unnecessary, if not do dump
-               if (!dump_neigh)
-                       dump_neigh_table(false);
-               else
-                       dump_neigh = false;
+               ndp_event.uloop.fd = sock;
+               odhcpd_register(&ndp_event);
+       } else if (!enable_packet && ndp_event.uloop.fd >= 0) {
+               close(ndp_event.uloop.fd);
+               ndp_event.uloop.fd = -1;
        }
-       close(procfd);
-
-       if (dump_neigh)
-               dump_neigh_table(true);
 
        return 0;
 }
@@ -240,14 +266,61 @@ static void handle_solicit(void *addr, void *data, size_t len,
 
        uint8_t mac[6];
        odhcpd_get_mac(iface, mac);
-       if (!memcmp(ll->sll_addr, mac, sizeof(mac)))
+       if (!memcmp(ll->sll_addr, mac, sizeof(mac)) &&
+                       ll->sll_pkttype != PACKET_OUTGOING)
                return; // Looped back
 
-       struct interface *c;
-       list_for_each_entry(c, &interfaces, head)
-               if (iface->ndp == RELAYD_RELAY && iface != c &&
-                               (!ns_is_dad || !c->external == false))
-                       ping6(&req->nd_ns_target, c);
+       time_t now = time(NULL);
+
+       struct ndp_neighbor *n = find_neighbor(&req->nd_ns_target, false);
+       if (n && (n->iface || abs(n->timeout - now) < 5)) {
+               syslog(LOG_DEBUG, "%s is on %s", ipbuf,
+                               (n->iface) ? n->iface->ifname : "<pending>");
+               if (!n->iface || n->iface == iface)
+                       return;
+
+               // Found on other interface, answer with advertisement
+               struct {
+                       struct nd_neighbor_advert body;
+                       struct nd_opt_hdr opt_ll_hdr;
+                       uint8_t mac[6];
+               } advert = {
+                       .body = {
+                               .nd_na_hdr = {ND_NEIGHBOR_ADVERT,
+                                       0, 0, {{0}}},
+                               .nd_na_target = req->nd_ns_target,
+                       },
+                       .opt_ll_hdr = {ND_OPT_TARGET_LINKADDR, 1},
+               };
+
+               memcpy(advert.mac, mac, sizeof(advert.mac));
+               advert.body.nd_na_flags_reserved = ND_NA_FLAG_ROUTER |
+                               ND_NA_FLAG_SOLICITED;
+
+               struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0};
+               if (!ns_is_dad) // If not DAD, then unicast to source
+                       dest.sin6_addr = ip6->ip6_src;
+
+               // 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));
+               struct iovec iov = {&advert, sizeof(advert)};
+               odhcpd_send(ping_socket, &dest, &iov, 1, iface);
+       } else {
+               // Send echo to all other interfaces to see where target is on
+               // This will trigger neighbor discovery which is what we want.
+               // We will observe the neighbor cache to see results.
+
+               ssize_t sent = 0;
+               struct interface *c;
+               list_for_each_entry(c, &interfaces, head)
+                       if (iface->ndp == RELAYD_RELAY && iface != c &&
+                                       (!ns_is_dad || !c->external == false))
+                               sent += ping6(&req->nd_ns_target, c);
+
+               if (sent > 0) // Sent a ping, add pending neighbor entry
+                       modify_neighbor(&req->nd_ns_target, NULL, true);
+       }
 }
 
 
@@ -311,15 +384,74 @@ static void setup_route(struct in6_addr *addr, struct interface *iface,
        odhcpd_setup_route(addr, 128, iface, NULL, add);
 }
 
+static void free_neighbor(struct ndp_neighbor *n)
+{
+       setup_route(&n->addr, n->iface, false);
+       list_del(&n->head);
+       free(n);
+       --neighbor_count;
+}
+
+static struct ndp_neighbor* find_neighbor(struct in6_addr *addr, bool strict)
+{
+       time_t now = time(NULL);
+       struct ndp_neighbor *n, *e;
+       list_for_each_entry_safe(n, e, &neighbors, head) {
+               if ((!strict && !odhcpd_bmemcmp(&n->addr, addr, n->len)) ||
+                               (n->len == 128 && IN6_ARE_ADDR_EQUAL(&n->addr, addr)))
+                       return n;
+
+               if (!n->iface && abs(n->timeout - now) >= 5)
+                       free_neighbor(n);
+       }
+       return NULL;
+}
+
+
+// Modified our own neighbor-entries
+static void modify_neighbor(struct in6_addr *addr,
+               struct interface *iface, bool add)
+{
+       if (!addr || (void*)addr == (void*)iface)
+               return;
+
+       struct ndp_neighbor *n = find_neighbor(addr, true);
+       if (!add) { // Delete action
+               if (n && (!n->iface || n->iface == iface))
+                       free_neighbor(n);
+       } else if (!n) { // No entry yet, add one if possible
+               if (neighbor_count >= NDP_MAX_NEIGHBORS ||
+                               !(n = malloc(sizeof(*n))))
+                       return;
+
+               n->len = 128;
+               n->addr = *addr;
+               n->iface = iface;
+               if (!n->iface)
+                       time(&n->timeout);
+               list_add(&n->head, &neighbors);
+               ++neighbor_count;
+               setup_route(addr, n->iface, add);
+       } else if (n->iface == iface) {
+               if (!n->iface)
+                       time(&n->timeout);
+       } else if (iface && (!n->iface ||
+                       (!iface->external && n->iface->external))) {
+               setup_route(addr, n->iface, false);
+               n->iface = iface;
+               setup_route(addr, n->iface, add);
+       }
+       // TODO: In case a host switches interfaces we might want
+       // to set its old neighbor entry to NUD_STALE and ping it
+       // on the old interface to confirm if the MACs match.
+}
+
 
 // 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)
 {
-       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);
@@ -374,103 +506,35 @@ static void handle_rtnetlink(_unused void *addr, void *data, size_t len,
                                (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);
-                                       }
-                               }
+               if (iface->ndp == RELAYD_RELAY)
+                       modify_neighbor(addr, iface, add);
 
-                               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;
-                               }
-                       }
-               }
+               if (is_addr && iface->ra == RELAYD_SERVER)
+                       raise(SIGUSR1); // Inform about a change in addresses
 
-               if (is_addr) {
-                       if (iface->ra == RELAYD_SERVER)
-                               raise(SIGUSR1); // Inform about a change in addresses
+               if (is_addr && iface->dhcpv6 == RELAYD_SERVER)
+                       iface->ia_reconf = true;
 
-                       if (iface->dhcpv6 == RELAYD_SERVER)
-                               iface->ia_reconf = true;
+               if (iface->ndp == RELAYD_RELAY && is_addr && iface->master) {
+                       // Replay address changes on all slave interfaces
+                       nh->nlmsg_flags = NLM_F_REQUEST;
 
-                       if (iface->ndp == RELAYD_RELAY && iface->master) {
-                               // Replay address changes on all slave interfaces
-                               nh->nlmsg_flags = NLM_F_REQUEST;
+                       if (nh->nlmsg_type == RTM_NEWADDR)
+                               nh->nlmsg_flags |= NLM_F_CREATE | NLM_F_REPLACE;
 
-                               if (nh->nlmsg_type == RTM_NEWADDR)
-                                       nh->nlmsg_flags |= NLM_F_CREATE | NLM_F_REPLACE;
-
-                               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);
-                                       }
+                       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 (dump_neigh)
-               dump_neigh_table(false);
+               /* TODO: See if this is required for optimal operation
+               // Keep neighbor entries alive so we don't loose routes
+                */
+               if (add && (ndm->ndm_state & NUD_STALE))
+                       ping6(addr, iface);
+       }
 }