treewide: rework handling of netlink events

Rework the handling of netlink events by letting the different
modules ndp, ra, dhcpv6 and dhcpv4 install netevent handlers.
The installed netevent handlers are called by the netlink logic
passing an event indication together with event data.
Each netevent handler implements its own event logic; this
makes the code more modular and less complex by moving all
netlink code to netlink.c
While at it rename ia_addr and ia_addr_len into addr6 and
addr6_len respectively

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>

1 files changed, 59 insertions, 345 deletions

diff --git a/src/ndp.c b/src/ndp.c
index 460d5fc..a9dbd9a 100644
--- a/src/ndp.c
+++ b/src/ndp.c
@@ -26,39 +26,20 @@
 #include <netinet/icmp6.h>
 #include <netpacket/packet.h>
 
-#include <linux/rtnetlink.h>
 #include <linux/filter.h>
-
-#include <netlink/msg.h>
-#include <netlink/socket.h>
-#include <netlink/attr.h>
+#include <linux/neighbour.h>
 
 #include "dhcpv6.h"
 #include "odhcpd.h"
 
-struct event_socket {
-	struct odhcpd_event ev;
-	struct nl_sock *sock;
-	int sock_bufsize;
-};
 
+static void ndp_netevent_cb(unsigned long event, struct netevent_handler_info *info);
+static void setup_route(struct in6_addr *addr, struct interface *iface, bool add);
+static void setup_addr_for_relaying(struct in6_addr *addr, struct interface *iface, bool add);
 static void handle_solicit(void *addr, void *data, size_t len,
 		struct interface *iface, void *dest);
-static void handle_rtnl_event(struct odhcpd_event *ev);
-static int cb_rtnl_valid(struct nl_msg *msg, void *arg);
-static void catch_rtnl_err(struct odhcpd_event *e, int error);
 
 static int ping_socket = -1;
-static struct event_socket rtnl_event = {
-	.ev = {
-		.uloop = {.fd = - 1, },
-		.handle_dgram = NULL,
-		.handle_error = catch_rtnl_err,
-		.recv_msgs = handle_rtnl_event,
-	},
-	.sock = NULL,
-	.sock_bufsize = 133120,
-};
 
 // Filter ICMPv6 messages of type neighbor soliciation
 static struct sock_filter bpf[] = {
@@ -71,35 +52,13 @@ static struct sock_filter bpf[] = {
 	BPF_STMT(BPF_RET | BPF_K, 0),
 };
 static const struct sock_fprog bpf_prog = {sizeof(bpf) / sizeof(*bpf), bpf};
-
+static struct netevent_handler ndp_netevent_handler = { .cb = ndp_netevent_cb, };
 
 // Initialize NDP-proxy
 int ndp_init(void)
 {
 	int val = 2;
 
-	rtnl_event.sock = netlink_create_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, rtnl_event.sock_bufsize, 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 IPv4 address, IPv6 address, IPv6 routes and neighbor events
-	if (nl_socket_add_memberships(rtnl_event.sock, RTNLGRP_IPV4_IFADDR,
-				RTNLGRP_IPV6_IFADDR, RTNLGRP_IPV6_ROUTE,
-				RTNLGRP_NEIGH, RTNLGRP_LINK, 0))
-		goto err;
-
-	odhcpd_register(&rtnl_event.ev);
-
 	// Open ICMPv6 socket
 	ping_socket = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
 	if (ping_socket < 0) {
@@ -119,53 +78,9 @@ int ndp_init(void)
 	ICMP6_FILTER_SETBLOCKALL(&filt);
 	setsockopt(ping_socket, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
 
-	return 0;
-
-err:
-	if (rtnl_event.sock) {
-		nl_socket_free(rtnl_event.sock);
-		rtnl_event.sock = NULL;
-		rtnl_event.ev.uloop.fd = -1;
-	}
-
-	return -1;
-}
+	netlink_add_netevent_handler(&ndp_netevent_handler);
 
-static void dump_neigh_table(const bool proxy)
-{
-	struct nl_msg *msg;
-	struct ndmsg ndm = {
-		.ndm_family = AF_INET6,
-		.ndm_flags = proxy ? NTF_PROXY : 0,
-	};
-
-	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(bool v6)
-{
-	struct nl_msg *msg;
-	struct ifaddrmsg ifa = {
-		.ifa_family = v6 ? AF_INET6 : AF_INET,
-	};
-
-	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);
+	return 0;
 }
 
 int ndp_setup_interface(struct interface *iface, bool enable)
@@ -236,13 +151,13 @@ int ndp_setup_interface(struct interface *iface, bool enable)
 
 		// If we already were enabled dump is unnecessary, if not do dump
 		if (!dump_neigh)
-			dump_neigh_table(false);
+			netlink_dump_neigh_table(false);
 		else
 			dump_neigh = false;
 	}
 
 	if (dump_neigh)
-		dump_neigh_table(true);
+		netlink_dump_neigh_table(true);
 
 out:
 	if (procfd >= 0)
@@ -251,6 +166,48 @@ out:
 	return ret;
 }
 
+static void ndp_netevent_cb(unsigned long event, struct netevent_handler_info *info)
+{
+	struct interface *iface = info->iface;
+	bool add = true;
+
+	if (!iface || iface->ndp == MODE_DISABLED)
+		return;
+
+	switch (event) {
+	case NETEV_ADDR6_DEL:
+		add = false;
+		netlink_dump_neigh_table(false);
+	case NETEV_ADDR6_ADD:
+		setup_addr_for_relaying(&info->addr.in6, iface, add);
+		break;
+	case NETEV_NEIGH6_DEL:
+		add = false;
+	case NETEV_NEIGH6_ADD:
+		if (info->neigh.flags & NTF_PROXY) {
+			if (add) {
+				netlink_setup_proxy_neigh(&info->neigh.dst.in6, iface->ifindex, false);
+				setup_route(&info->neigh.dst.in6, iface, false);
+				netlink_dump_neigh_table(false);
+			}
+			break;
+		}
+
+		if (add &&
+		    !(info->neigh.state &
+		      (NUD_REACHABLE|NUD_STALE|NUD_DELAY|NUD_PROBE|NUD_PERMANENT|NUD_NOARP)))
+			break;
+
+		setup_addr_for_relaying(&info->neigh.dst.in6, iface, add);
+		setup_route(&info->neigh.dst.in6, iface, add);
+
+		if (!add)
+			netlink_dump_neigh_table(false);
+		break;
+	default:
+		break;
+	}
+}
 
 // Send an ICMP-ECHO. This is less for actually pinging but for the
 // neighbor cache to be kept up-to-date.
@@ -265,9 +222,9 @@ static void ping6(struct in6_addr *addr,
 	inet_ntop(AF_INET6, addr, ipbuf, sizeof(ipbuf));
 	syslog(LOG_NOTICE, "Pinging for %s%%%s", ipbuf, iface->ifname);
 
-	netlink_setup_route(addr, 128, iface, NULL, 128, true);
+	netlink_setup_route(addr, 128, iface->ifindex, NULL, 128, true);
 	odhcpd_send(ping_socket, &dest, &iov, 1, iface);
-	netlink_setup_route(addr, 128, iface, NULL, 128, false);
+	netlink_setup_route(addr, 128, iface->ifindex, NULL, 128, false);
 }
 
 // Handle solicitations
@@ -317,64 +274,13 @@ static void setup_route(struct in6_addr *addr, struct interface *iface, bool add
 	char ipbuf[INET6_ADDRSTRLEN];
 
 	inet_ntop(AF_INET6, addr, ipbuf, sizeof(ipbuf));
-	syslog(LOG_NOTICE, "%s about %s%%%s",
-			(add) ? "Learned" : "Forgot", ipbuf, iface->ifname);
+	syslog(LOG_NOTICE, "%s about %s%s%%%s",
+			(add) ? "Learning" : "Forgetting",
+			iface->learn_routes ? "proxy routing for " : "",
+			ipbuf, iface->ifname);
 
 	if (iface->learn_routes)
-		netlink_setup_route(addr, 128, iface, NULL, 1024, add);
-}
-
-// Check address update
-static void check_addr_updates(struct interface *iface)
-{
-	struct odhcpd_ipaddr *addr = NULL;
-	ssize_t len = netlink_get_interface_addrs(iface->ifindex, false, &addr);
-
-	if (len < 0)
-		return;
-
-	bool change = len != (ssize_t)iface->addr4_len;
-	for (ssize_t i = 0; !change && i < len; ++i)
-		if (addr[i].addr.in.s_addr != iface->addr4[i].addr.in.s_addr)
-			change = true;
-
-	free(iface->addr4);
-	iface->addr4 = addr;
-	iface->addr4_len = len;
-
-	if (change)
-		dhcpv4_addr_update(iface);
-}
-
-// Check v6 address update
-static void check_addr6_updates(struct interface *iface)
-{
-	struct odhcpd_ipaddr *addr = NULL;
-	ssize_t len = netlink_get_interface_addrs(iface->ifindex, true, &addr);
-
-	if (len < 0)
-		return;
-
-	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.in6, &iface->ia_addr[i].addr.in6) ||
-				(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);
-
-	free(iface->ia_addr);
-	iface->ia_addr = addr;
-	iface->ia_addr_len = len;
-
-	if (change) {
-		dhcpv6_ia_postupdate(iface);
-		syslog(LOG_INFO, "Raising SIGUSR1 due to address change on %s", iface->ifname);
-		raise(SIGUSR1);
-	}
+		netlink_setup_route(addr, 128, iface->ifindex, NULL, 1024, add);
 }
 
 static void setup_addr_for_relaying(struct in6_addr *addr, struct interface *iface, bool add)
@@ -390,7 +296,7 @@ static void setup_addr_for_relaying(struct in6_addr *addr, struct interface *ifa
 
 		bool neigh_add = (c->ndp == MODE_RELAY ? add : false);
 
-		if (netlink_setup_proxy_neigh(addr, c, neigh_add))
+		if (netlink_setup_proxy_neigh(addr, c->ifindex, neigh_add))
 			syslog(LOG_DEBUG, "Failed to %s proxy neighbour entry %s%%%s",
 				neigh_add ? "add" : "delete", ipbuf, c->ifname);
 		else
@@ -398,195 +304,3 @@ static void setup_addr_for_relaying(struct in6_addr *addr, struct interface *ifa
 				neigh_add ? "Added" : "Deleted", ipbuf, c->ifname);
 	}
 }
-
-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 int cb_rtnl_valid(struct nl_msg *msg, _unused void *arg)
-{
-	struct nlmsghdr *hdr = nlmsg_hdr(msg);
-	struct in6_addr *addr6 = NULL;
-	struct interface *iface = NULL;
-	bool add = false;
-	char ipbuf[INET6_ADDRSTRLEN];
-
-	switch (hdr->nlmsg_type) {
-	case RTM_NEWLINK: {
-		struct ifinfomsg *ifi = nlmsg_data(hdr);
-		struct nlattr *nla[__IFLA_MAX];
-
-		if (!nlmsg_valid_hdr(hdr, sizeof(*ifi)) ||
-				ifi->ifi_family != AF_UNSPEC)
-			return NL_SKIP;
-
-		nlmsg_parse(hdr, sizeof(struct ifinfomsg), nla, __IFLA_MAX - 1, NULL);
-		if (!nla[IFLA_IFNAME])
-			return NL_SKIP;
-
-		struct interface *iface = odhcpd_get_interface_by_name(nla_data(nla[IFLA_IFNAME]));
-		if (!iface)
-			return NL_SKIP;
-
-		if (iface->ifindex != ifi->ifi_index) {
-			iface->ifindex = ifi->ifi_index;
-			check_addr_updates(iface);
-		}
-		break;
-	}
-
-	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);
-		}
-		break;
-	}
-
-	case RTM_NEWADDR:
-		add = true;
-		/* fall through */
-	case RTM_DELADDR: {
-		struct ifaddrmsg *ifa = nlmsg_data(hdr);
-		struct nlattr *nla[__IFA_MAX];
-
-		if (!nlmsg_valid_hdr(hdr, sizeof(*ifa)) ||
-				(ifa->ifa_family != AF_INET6 &&
-				 ifa->ifa_family != AF_INET))
-			return NL_SKIP;
-
-		iface = odhcpd_get_interface_by_index(ifa->ifa_index);
-		if (!iface)
-			return NL_SKIP;
-
-		nlmsg_parse(hdr, sizeof(*ifa), nla, __IFA_MAX - 1, NULL);
-
-		if (ifa->ifa_family == AF_INET6) {
-			if (!nla[IFA_ADDRESS])
-				return NL_SKIP;
-
-			addr6 = nla_data(nla[IFA_ADDRESS]);
-			if (!addr6 || IN6_IS_ADDR_LINKLOCAL(addr6) ||
-					IN6_IS_ADDR_MULTICAST(addr6))
-				return NL_SKIP;
-
-			inet_ntop(AF_INET6, addr6, ipbuf, sizeof(ipbuf));
-			syslog(LOG_DEBUG, "Netlink %s %s%%%s", add ? "newaddr" : "deladdr",
-				ipbuf, iface->ifname);
-
-			check_addr6_updates(iface);
-
-			if (iface->ndp != MODE_RELAY)
-				break;
-
-			/* handle the relay logic below */
-			setup_addr_for_relaying(addr6, iface, add);
-
-			if (!add)
-				dump_neigh_table(false);
-		} else {
-			if (!nla[IFA_LOCAL])
-				return NL_SKIP;
-
-			struct in_addr *addr = nla_data(nla[IFA_ADDRESS]);
-
-			inet_ntop(AF_INET, addr, ipbuf, sizeof(ipbuf));
-			syslog(LOG_DEBUG, "Netlink %s %s%%%s", add ? "newaddr" : "deladdr",
-				ipbuf, iface->ifname);
-
-			check_addr_updates(iface);
-		}
-		break;
-	}
-
-	case RTM_NEWNEIGH:
-		add = true;
-		/* fall through */
-	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 != MODE_RELAY)
-			return (iface ? NL_OK : NL_SKIP);
-
-		nlmsg_parse(hdr, sizeof(*ndm), nla, __NDA_MAX - 1, NULL);
-		if (!nla[NDA_DST])
-			return NL_SKIP;
-
-		addr6 = nla_data(nla[NDA_DST]);
-		if (!addr6 || IN6_IS_ADDR_LINKLOCAL(addr6) ||
-				IN6_IS_ADDR_MULTICAST(addr6))
-			return NL_SKIP;
-
-		inet_ntop(AF_INET6, addr6, ipbuf, sizeof(ipbuf));
-		syslog(LOG_DEBUG, "Netlink %s %s%%%s", true ? "newneigh" : "delneigh",
-			ipbuf, iface->ifname);
-
-		if (ndm->ndm_flags & NTF_PROXY) {
-			/* Dump and flush proxy entries */
-			if (hdr->nlmsg_type == RTM_NEWNEIGH) {
-				netlink_setup_proxy_neigh(addr6, iface, false);
-				setup_route(addr6, iface, false);
-				dump_neigh_table(false);
-			}
-
-			return NL_OK;
-		}
-
-		if (add && !(ndm->ndm_state &
-				(NUD_REACHABLE | NUD_STALE | NUD_DELAY | NUD_PROBE |
-				 NUD_PERMANENT | NUD_NOARP)))
-			return NL_OK;
-
-		setup_addr_for_relaying(addr6, iface, add);
-		setup_route(addr6, iface, add);
-
-		if (!add)
-			dump_neigh_table(false);
-		break;
-	}
-
-	default:
-		return NL_SKIP;
-	}
-
-	return NL_OK;
-}
-
-static void catch_rtnl_err(struct odhcpd_event *e, int error)
-{
-	struct event_socket *ev_sock = container_of(e, struct event_socket, ev);
-
-	if (error != ENOBUFS)
-		goto err;
-
-	/* Double netlink event buffer size */
-	ev_sock->sock_bufsize *= 2;
-
-	if (nl_socket_set_buffer_size(ev_sock->sock, ev_sock->sock_bufsize, 0))
-		goto err;
-
-	dump_addr_table(true);
-	return;
-
-err:
-	odhcpd_deregister(e);
-}