nhrpd: implement next hop resolution protocol
This provides DMVPN support and integrates to strongSwan. Please read
README.nhrpd and README.kernel for more details.
diff --git a/nhrpd/netlink_arp.c b/nhrpd/netlink_arp.c
new file mode 100644
index 0000000..a418eca
--- /dev/null
+++ b/nhrpd/netlink_arp.c
@@ -0,0 +1,275 @@
+/* NHRP netlink/neighbor table arpd code
+ * Copyright (c) 2014-2016 Timo Teräs
+ *
+ * This file is free software: you may copy, redistribute and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <fcntl.h>
+#include <net/if.h>
+#include <netinet/if_ether.h>
+#include <linux/netlink.h>
+#include <linux/neighbour.h>
+#include <linux/netfilter/nfnetlink_log.h>
+
+#include "thread.h"
+#include "nhrpd.h"
+#include "netlink.h"
+#include "znl.h"
+
+int netlink_req_fd = -1;
+int netlink_nflog_group;
+static int netlink_log_fd = -1;
+static struct thread *netlink_log_thread;
+static int netlink_listen_fd = -1;
+
+typedef void (*netlink_dispatch_f)(struct nlmsghdr *msg, struct zbuf *zb);
+
+void netlink_update_binding(struct interface *ifp, union sockunion *proto, union sockunion *nbma)
+{
+ struct nlmsghdr *n;
+ struct ndmsg *ndm;
+ struct zbuf *zb = zbuf_alloc(512);
+
+ n = znl_nlmsg_push(zb, nbma ? RTM_NEWNEIGH : RTM_DELNEIGH, NLM_F_REQUEST | NLM_F_REPLACE | NLM_F_CREATE);
+ ndm = znl_push(zb, sizeof(*ndm));
+ *ndm = (struct ndmsg) {
+ .ndm_family = sockunion_family(proto),
+ .ndm_ifindex = ifp->ifindex,
+ .ndm_type = RTN_UNICAST,
+ .ndm_state = nbma ? NUD_REACHABLE : NUD_FAILED,
+ };
+ znl_rta_push(zb, NDA_DST, sockunion_get_addr(proto), family2addrsize(sockunion_family(proto)));
+ if (nbma)
+ znl_rta_push(zb, NDA_LLADDR, sockunion_get_addr(nbma), family2addrsize(sockunion_family(nbma)));
+ znl_nlmsg_complete(zb, n);
+ zbuf_send(zb, netlink_req_fd);
+ zbuf_recv(zb, netlink_req_fd);
+ zbuf_free(zb);
+}
+
+static void netlink_neigh_msg(struct nlmsghdr *msg, struct zbuf *zb)
+{
+ struct ndmsg *ndm;
+ struct rtattr *rta;
+ struct nhrp_cache *c;
+ struct interface *ifp;
+ struct zbuf payload;
+ union sockunion addr;
+ size_t len;
+ char buf[SU_ADDRSTRLEN];
+ int state;
+
+ ndm = znl_pull(zb, sizeof(*ndm));
+ if (!ndm) return;
+
+ sockunion_family(&addr) = AF_UNSPEC;
+ while ((rta = znl_rta_pull(zb, &payload)) != NULL) {
+ len = zbuf_used(&payload);
+ switch (rta->rta_type) {
+ case NDA_DST:
+ sockunion_set(&addr, ndm->ndm_family, zbuf_pulln(&payload, len), len);
+ break;
+ }
+ }
+
+ ifp = if_lookup_by_index(ndm->ndm_ifindex);
+ if (!ifp || sockunion_family(&addr) == AF_UNSPEC)
+ return;
+
+ c = nhrp_cache_get(ifp, &addr, 0);
+ if (!c)
+ return;
+
+ if (msg->nlmsg_type == RTM_GETNEIGH) {
+ debugf(NHRP_DEBUG_KERNEL, "Netlink: who-has %s dev %s",
+ sockunion2str(&addr, buf, sizeof buf),
+ ifp->name);
+
+ if (c->cur.type >= NHRP_CACHE_CACHED) {
+ nhrp_cache_set_used(c, 1);
+ netlink_update_binding(ifp, &addr, &c->cur.peer->vc->remote.nbma);
+ }
+ } else {
+ debugf(NHRP_DEBUG_KERNEL, "Netlink: update %s dev %s nud %x",
+ sockunion2str(&addr, buf, sizeof buf),
+ ifp->name, ndm->ndm_state);
+
+ state = (msg->nlmsg_type == RTM_NEWNEIGH) ? ndm->ndm_state : NUD_FAILED;
+ nhrp_cache_set_used(c, state == NUD_REACHABLE);
+ }
+}
+
+static int netlink_route_recv(struct thread *t)
+{
+ uint8_t buf[ZNL_BUFFER_SIZE];
+ int fd = THREAD_FD(t);
+ struct zbuf payload, zb;
+ struct nlmsghdr *n;
+
+ zbuf_init(&zb, buf, sizeof(buf), 0);
+ while (zbuf_recv(&zb, fd) > 0) {
+ while ((n = znl_nlmsg_pull(&zb, &payload)) != 0) {
+ debugf(NHRP_DEBUG_KERNEL, "Netlink: Received msg_type %u, msg_flags %u",
+ n->nlmsg_type, n->nlmsg_flags);
+ switch (n->nlmsg_type) {
+ case RTM_GETNEIGH:
+ case RTM_NEWNEIGH:
+ case RTM_DELNEIGH:
+ netlink_neigh_msg(n, &payload);
+ break;
+ }
+ }
+ }
+
+ thread_add_read(master, netlink_route_recv, 0, fd);
+
+ return 0;
+}
+
+static void netlink_log_register(int fd, int group)
+{
+ struct nlmsghdr *n;
+ struct nfgenmsg *nf;
+ struct nfulnl_msg_config_cmd cmd;
+ struct zbuf *zb = zbuf_alloc(512);
+
+ n = znl_nlmsg_push(zb, (NFNL_SUBSYS_ULOG<<8) | NFULNL_MSG_CONFIG, NLM_F_REQUEST | NLM_F_ACK);
+ nf = znl_push(zb, sizeof(*nf));
+ *nf = (struct nfgenmsg) {
+ .nfgen_family = AF_UNSPEC,
+ .version = NFNETLINK_V0,
+ .res_id = htons(group),
+ };
+ cmd.command = NFULNL_CFG_CMD_BIND;
+ znl_rta_push(zb, NFULA_CFG_CMD, &cmd, sizeof(cmd));
+ znl_nlmsg_complete(zb, n);
+
+ zbuf_send(zb, fd);
+ zbuf_free(zb);
+}
+
+static void netlink_log_indication(struct nlmsghdr *msg, struct zbuf *zb)
+{
+ struct nfgenmsg *nf;
+ struct rtattr *rta;
+ struct zbuf rtapl, pktpl;
+ struct interface *ifp;
+ struct nfulnl_msg_packet_hdr *pkthdr = NULL;
+ uint32_t *in_ndx = NULL;
+
+ nf = znl_pull(zb, sizeof(*nf));
+ if (!nf) return;
+
+ memset(&pktpl, 0, sizeof(pktpl));
+ while ((rta = znl_rta_pull(zb, &rtapl)) != NULL) {
+ switch (rta->rta_type) {
+ case NFULA_PACKET_HDR:
+ pkthdr = znl_pull(&rtapl, sizeof(*pkthdr));
+ break;
+ case NFULA_IFINDEX_INDEV:
+ in_ndx = znl_pull(&rtapl, sizeof(*in_ndx));
+ break;
+ case NFULA_PAYLOAD:
+ pktpl = rtapl;
+ break;
+ /* NFULA_HWHDR exists and is supposed to contain source
+ * hardware address. However, for ip_gre it seems to be
+ * the nexthop destination address if the packet matches
+ * route. */
+ }
+ }
+
+ if (!pkthdr || !in_ndx || !zbuf_used(&pktpl))
+ return;
+
+ ifp = if_lookup_by_index(htonl(*in_ndx));
+ if (!ifp)
+ return;
+
+ nhrp_peer_send_indication(ifp, htons(pkthdr->hw_protocol), &pktpl);
+}
+
+static int netlink_log_recv(struct thread *t)
+{
+ uint8_t buf[ZNL_BUFFER_SIZE];
+ int fd = THREAD_FD(t);
+ struct zbuf payload, zb;
+ struct nlmsghdr *n;
+
+ netlink_log_thread = NULL;
+
+ zbuf_init(&zb, buf, sizeof(buf), 0);
+ while (zbuf_recv(&zb, fd) > 0) {
+ while ((n = znl_nlmsg_pull(&zb, &payload)) != 0) {
+ debugf(NHRP_DEBUG_KERNEL, "Netlink-log: Received msg_type %u, msg_flags %u",
+ n->nlmsg_type, n->nlmsg_flags);
+ switch (n->nlmsg_type) {
+ case (NFNL_SUBSYS_ULOG<<8) | NFULNL_MSG_PACKET:
+ netlink_log_indication(n, &payload);
+ break;
+ }
+ }
+ }
+
+ THREAD_READ_ON(master, netlink_log_thread, netlink_log_recv, 0, netlink_log_fd);
+
+ return 0;
+}
+
+void netlink_set_nflog_group(int nlgroup)
+{
+ if (netlink_log_fd >= 0) {
+ THREAD_OFF(netlink_log_thread);
+ close(netlink_log_fd);
+ netlink_log_fd = -1;
+ }
+ netlink_nflog_group = nlgroup;
+ if (nlgroup) {
+ netlink_log_fd = znl_open(NETLINK_NETFILTER, 0);
+ netlink_log_register(netlink_log_fd, nlgroup);
+ THREAD_READ_ON(master, netlink_log_thread, netlink_log_recv, 0, netlink_log_fd);
+ }
+}
+
+int netlink_init(void)
+{
+ netlink_req_fd = znl_open(NETLINK_ROUTE, 0);
+ netlink_listen_fd = znl_open(NETLINK_ROUTE, RTMGRP_NEIGH);
+ thread_add_read(master, netlink_route_recv, 0, netlink_listen_fd);
+
+ return 0;
+}
+
+int netlink_configure_arp(unsigned int ifindex, int pf)
+{
+ struct nlmsghdr *n;
+ struct ndtmsg *ndtm;
+ struct rtattr *rta;
+ struct zbuf *zb = zbuf_alloc(512);
+ int r;
+
+ n = znl_nlmsg_push(zb, RTM_SETNEIGHTBL, NLM_F_REQUEST | NLM_F_REPLACE);
+ ndtm = znl_push(zb, sizeof(*ndtm));
+ *ndtm = (struct ndtmsg) {
+ .ndtm_family = pf,
+ };
+
+ znl_rta_push(zb, NDTA_NAME, pf == AF_INET ? "arp_cache" : "ndisc_cache", 10);
+
+ rta = znl_rta_nested_push(zb, NDTA_PARMS);
+ znl_rta_push_u32(zb, NDTPA_IFINDEX, ifindex);
+ znl_rta_push_u32(zb, NDTPA_APP_PROBES, 1);
+ znl_rta_push_u32(zb, NDTPA_MCAST_PROBES, 0);
+ znl_rta_push_u32(zb, NDTPA_UCAST_PROBES, 0);
+ znl_rta_nested_complete(zb, rta);
+
+ znl_nlmsg_complete(zb, n);
+ r = zbuf_send(zb, netlink_req_fd);
+ zbuf_recv(zb, netlink_req_fd);
+ zbuf_free(zb);
+
+ return r;
+}