First Netlink plugin prototype.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

plugins/Makefile

@@ -7,7 +7,8 @@ LDFLAGS    := $(filter-out -rdynamic, $(LDFLAGS))
 LDFLAGS    += -shared
 ifneq ($(STATIC), 1)
 PLUGINS    ?= initctl.so alsa-utils.so bootmisc.so dbus.so hwclock.so \
-	      resolvconf.so urandom.so x11-common.so tty.so time.so
+	      resolvconf.so urandom.so x11-common.so tty.so time.so   \
+	      netlink.so
 DEPS       := $(PLUGINS:.so=.d)
 endif
 

plugins/netlink.c

@@ -0,0 +1,193 @@
+/* Netlink plugin for IFUP/IFDN and GW events
+ *
+ * Copyright (C) 2009-2011  Mårten Wikström <marten.wikstrom@keystream.se>
+ * Copyright (C) 2009-2015  Joachim Nilsson <troglobit@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <errno.h>
+#include <net/if.h>		/* IFNAMSIZ */
+//#include <stdint.h>
+#include <sys/socket.h>
+#include <linux/types.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <unistd.h>
+
+#include "../finit.h"
+#include "../helpers.h"
+#include "../plugin.h"
+
+static void nl_callback(void *UNUSED(arg), int sd, int UNUSED(events))
+{
+	ssize_t bytes;
+	static char replybuf[2048];
+	struct nlmsghdr *p = (struct nlmsghdr *)replybuf;
+
+	memset(replybuf, 0, sizeof(replybuf));
+	bytes = recv(sd, replybuf, sizeof(replybuf), 0);
+	if (bytes < 0) {
+		if (errno != EINTR)	/* Signal */
+			_pe("recv()");
+		return;
+	}
+
+	for (; bytes > 0; p = NLMSG_NEXT(p, bytes)) {
+		if (!NLMSG_OK(p, (size_t)bytes)
+		    || (size_t)bytes < sizeof(struct nlmsghdr)
+		    || (size_t)bytes < p->nlmsg_len) {
+			_e("Packet too small or truncated!");
+			return;
+		}
+
+		/* Check if this message is about the routing table */
+		if (p->nlmsg_type == RTM_NEWROUTE) {
+			struct rtmsg *r;
+			struct rtattr *a;
+			int la;
+			int gw = 0, dst = 0, mask = 0, idx = 0;
+
+			if (p->nlmsg_len < NLMSG_LENGTH(sizeof(struct rtmsg))) {
+				_e("Packet too small or truncated!");
+				return;
+			}
+
+			r  = NLMSG_DATA(p);
+			a  = RTM_RTA(r);
+			la = RTM_PAYLOAD(p);
+			while (RTA_OK(a, la)) {
+				void *data = RTA_DATA(a);
+				switch (a->rta_type) {
+				case RTA_GATEWAY:
+					gw = *((int *)data);
+					break;
+
+				case RTA_DST:
+					dst = *((int *)data);
+					mask = r->rtm_dst_len;
+					break;
+
+				case RTA_OIF:
+					idx = *((int *)data);
+					break;
+				}
+
+				a = RTA_NEXT(a, la);
+			}
+
+			if ((!dst && !mask) && (gw || idx)) {
+				_d("Default gateway changed --> 0x%4x", gw);
+			}
+		} else {
+			/* If not about the routing table, assume it is linkup/down or new ipv4/ipv6 address */
+			int la;
+			char ifname[IFNAMSIZ + 1];
+			struct rtattr *a;
+			struct ifinfomsg *i;
+
+			if (p->nlmsg_len < NLMSG_LENGTH(sizeof(struct ifinfomsg))) {
+				_e("Packet too small or truncated!");
+				return;
+			}
+
+			i  = NLMSG_DATA(p);
+			a  = (struct rtattr *)((char *)i + NLMSG_ALIGN(sizeof(struct ifinfomsg)));
+			la = NLMSG_PAYLOAD(p, sizeof(struct ifinfomsg));
+
+			while (RTA_OK(a, la)) {
+				if (a->rta_type == IFLA_IFNAME) {
+					strncpy(ifname, RTA_DATA(a), sizeof(ifname));
+					switch (p->nlmsg_type) {
+					case RTM_NEWLINK:
+						/* New interface has appearad, or interface flags has changed.
+						 * Check ifi_flags here to see if the interface is UP/DOWN
+						 */
+						_d("New link (%s), UP: %d", ifname, i->ifi_flags & IFF_UP);
+						if (i->ifi_change & IFF_UP) {
+							int msg = (i->ifi_flags & IFF_UP) ? 1 : 0;
+
+							_d("%s: %s", ifname, msg ? "UP" : "DOWN");
+						}
+						break;
+
+					case RTM_DELLINK:
+						/* NOTE: Interface has dissapeared, not link down ... */
+						_d("%s: DOWN", ifname);
+						break;
+
+					case RTM_NEWADDR:
+						_d("%s: New Address", ifname);
+						break;
+
+					case RTM_DELADDR:
+						_d("%s: Deconfig Address", ifname);
+						break;
+
+					default:
+						_d("%s: Msg 0x%x", ifname, p->nlmsg_type);
+						break;
+					}
+				}
+
+				a = RTA_NEXT(a, la);
+			}
+		}
+	}
+}
+
+static plugin_t plugin = {
+	.io = {
+		.cb    = nl_callback,
+		.flags = PLUGIN_IO_READ,
+	},
+};
+
+PLUGIN_INIT(plugin_init)
+{
+	int sd;
+	struct sockaddr_nl addr;
+
+	sd = socket(PF_NETLINK, SOCK_DGRAM | SOCK_NONBLOCK | SOCK_CLOEXEC, NETLINK_ROUTE);
+	if (sd < 0) {
+		_pe("socket()");
+		return;
+	}
+
+	memset(&addr, 0, sizeof(addr));
+	addr.nl_family = AF_NETLINK;
+	addr.nl_groups = RTMGRP_IPV4_ROUTE | RTMGRP_LINK;
+	addr.nl_pid    = getpid();
+
+	if (bind(sd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
+		_pe("bind()");
+		close(sd);
+		return;
+	}
+
+	plugin.io.fd = sd;
+	plugin_register(&plugin);
+}
+
+PLUGIN_EXIT(plugin_exit)
+{
+	plugin_unregister(&plugin);
+}
+
+/**
+ * Local Variables:
+ *  version-control: t
+ *  indent-tabs-mode: t
+ *  c-file-style: "linux"
+ * End:
+ */