treewide: add netlink file

First step in moving netlink code to netlink.c by
moving netlink code from odhcpd.c to netlink.c

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

1 files changed, 392 insertions, 0 deletions

diff --git a/src/netlink.c b/src/netlink.c
new file mode 100644
index 0000000..485fd57
--- /dev/null
+++ b/src/netlink.c
@@ -0,0 +1,392 @@
+/**
+ * Copyright (C) 2017 Hans Dedecker <dedeckeh@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License v2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <errno.h>
+#include <string.h>
+#include <syslog.h>
+
+#include <linux/netlink.h>
+#include <linux/if_addr.h>
+#include <linux/neighbour.h>
+#include <linux/rtnetlink.h>
+
+#include <netlink/msg.h>
+#include <netlink/socket.h>
+#include <netlink/attr.h>
+
+#include "odhcpd.h"
+
+static struct nl_sock *rtnl_socket = NULL;
+
+
+int netlink_init(void)
+{
+	if (!(rtnl_socket = netlink_create_socket(NETLINK_ROUTE))) {
+		syslog(LOG_ERR, "Unable to open nl socket: %s", strerror(errno));
+		return -1;
+	}
+
+	return 0;
+}
+
+
+struct nl_sock *netlink_create_socket(int protocol)
+{
+	struct nl_sock *nl_sock;
+
+	nl_sock = nl_socket_alloc();
+	if (!nl_sock)
+		goto err;
+
+	if (nl_connect(nl_sock, protocol) < 0)
+		goto err;
+
+	return nl_sock;
+
+err:
+	if (nl_sock)
+		nl_socket_free(nl_sock);
+
+	return NULL;
+}
+
+
+struct addr_info {
+	int ifindex;
+	int af;
+	struct odhcpd_ipaddr **addrs;
+	int pending;
+	ssize_t ret;
+};
+
+
+static int cb_valid_handler(struct nl_msg *msg, void *arg)
+{
+	struct addr_info *ctxt = (struct addr_info *)arg;
+	struct odhcpd_ipaddr *addrs = *(ctxt->addrs);
+	struct nlmsghdr *hdr = nlmsg_hdr(msg);
+	struct ifaddrmsg *ifa;
+	struct nlattr *nla[__IFA_MAX], *nla_addr = NULL;
+
+	if (hdr->nlmsg_type != RTM_NEWADDR)
+		return NL_SKIP;
+
+	ifa = NLMSG_DATA(hdr);
+	if (ifa->ifa_scope != RT_SCOPE_UNIVERSE ||
+			(ctxt->af != ifa->ifa_family) ||
+			(ctxt->ifindex && ifa->ifa_index != (unsigned)ctxt->ifindex))
+		return NL_SKIP;
+
+	nlmsg_parse(hdr, sizeof(*ifa), nla, __IFA_MAX - 1, NULL);
+
+	switch (ifa->ifa_family) {
+	case AF_INET6:
+		if (nla[IFA_ADDRESS])
+			nla_addr = nla[IFA_ADDRESS];
+		break;
+
+	case AF_INET:
+		if (nla[IFA_LOCAL])
+			nla_addr = nla[IFA_LOCAL];
+		break;
+
+	default:
+		break;
+	}
+	if (!nla_addr)
+		return NL_SKIP;
+
+	addrs = realloc(addrs, sizeof(*addrs)*(ctxt->ret + 1));
+	if (!addrs)
+		return NL_SKIP;
+
+	memset(&addrs[ctxt->ret], 0, sizeof(addrs[ctxt->ret]));
+	addrs[ctxt->ret].prefix = ifa->ifa_prefixlen;
+
+	nla_memcpy(&addrs[ctxt->ret].addr, nla_addr,
+			sizeof(addrs[ctxt->ret].addr));
+
+	if (nla[IFA_BROADCAST])
+		nla_memcpy(&addrs[ctxt->ret].broadcast, nla[IFA_BROADCAST],
+				sizeof(addrs[ctxt->ret].broadcast));
+
+	if (nla[IFA_CACHEINFO]) {
+		struct ifa_cacheinfo *ifc = nla_data(nla[IFA_CACHEINFO]);
+
+		addrs[ctxt->ret].preferred = ifc->ifa_prefered;
+		addrs[ctxt->ret].valid = ifc->ifa_valid;
+	}
+
+	if (ifa->ifa_flags & IFA_F_DEPRECATED)
+		addrs[ctxt->ret].preferred = 0;
+
+	ctxt->ret++;
+	*(ctxt->addrs) = addrs;
+
+	return NL_OK;
+}
+
+
+static int cb_finish_handler(_unused struct nl_msg *msg, void *arg)
+{
+	struct addr_info *ctxt = (struct addr_info *)arg;
+
+	ctxt->pending = 0;
+
+	return NL_STOP;
+}
+
+
+static int cb_error_handler(_unused struct sockaddr_nl *nla, struct nlmsgerr *err,
+		void *arg)
+{
+	struct addr_info *ctxt = (struct addr_info *)arg;
+
+	ctxt->pending = 0;
+	ctxt->ret = err->error;
+
+	return NL_STOP;
+}
+
+
+static int prefix_cmp(const void *va, const void *vb)
+{
+	const struct odhcpd_ipaddr *a = va, *b = vb;
+	int ret = 0;
+
+	if (a->prefix == b->prefix) {
+		ret = (ntohl(a->addr.in.s_addr) < ntohl(b->addr.in.s_addr)) ? 1 :
+			(ntohl(a->addr.in.s_addr) > ntohl(b->addr.in.s_addr)) ? -1 : 0;
+	} else
+		ret = a->prefix < b->prefix ? 1 : -1;
+
+	return ret;
+}
+
+
+// compare IPv6 prefixes
+static int prefix6_cmp(const void *va, const void *vb)
+{
+	const struct odhcpd_ipaddr *a = va, *b = vb;
+	uint32_t a_pref = IN6_IS_ADDR_ULA(&a->addr.in6) ? 1 : a->preferred;
+	uint32_t b_pref = IN6_IS_ADDR_ULA(&b->addr.in6) ? 1 : b->preferred;
+	return (a_pref < b_pref) ? 1 : (a_pref > b_pref) ? -1 : 0;
+}
+
+
+// Detect an IPV6-address currently assigned to the given interface
+ssize_t netlink_get_interface_addrs(int ifindex, bool v6, struct odhcpd_ipaddr **addrs)
+{
+	struct nl_msg *msg;
+	struct ifaddrmsg ifa = {
+		.ifa_family = v6? AF_INET6: AF_INET,
+		.ifa_prefixlen = 0,
+		.ifa_flags = 0,
+		.ifa_scope = 0,
+		.ifa_index = ifindex, };
+	struct nl_cb *cb = nl_cb_alloc(NL_CB_DEFAULT);
+	struct addr_info ctxt = {
+		.ifindex = ifindex,
+		.af = v6? AF_INET6: AF_INET,
+		.addrs = addrs,
+		.ret = 0,
+		.pending = 1,
+	};
+
+	if (!cb) {
+		ctxt.ret = -1;
+		goto out;
+	}
+
+	msg = nlmsg_alloc_simple(RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP);
+
+	if (!msg) {
+		ctxt.ret = - 1;
+		goto out;
+	}
+
+	nlmsg_append(msg, &ifa, sizeof(ifa), 0);
+
+	nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, cb_valid_handler, &ctxt);
+	nl_cb_set(cb, NL_CB_FINISH, NL_CB_CUSTOM, cb_finish_handler, &ctxt);
+	nl_cb_err(cb, NL_CB_CUSTOM, cb_error_handler, &ctxt);
+
+	nl_send_auto_complete(rtnl_socket, msg);
+	while (ctxt.pending > 0)
+		nl_recvmsgs(rtnl_socket, cb);
+
+	nlmsg_free(msg);
+
+	if (ctxt.ret <= 0)
+		goto out;
+
+	time_t now = odhcpd_time();
+	struct odhcpd_ipaddr *addr = *addrs;
+
+	qsort(addr, ctxt.ret, sizeof(*addr), v6 ? prefix6_cmp : prefix_cmp);
+
+	for (ssize_t i = 0; i < ctxt.ret; ++i) {
+		if (addr[i].preferred < UINT32_MAX - now)
+			addr[i].preferred += now;
+
+		if (addr[i].valid < UINT32_MAX - now)
+			addr[i].valid += now;
+	}
+
+out:
+	nl_cb_put(cb);
+
+	return ctxt.ret;
+}
+
+
+int netlink_setup_route(const struct in6_addr *addr, const int prefixlen,
+		const struct interface *iface, const struct in6_addr *gw,
+		const uint32_t metric, const bool add)
+{
+	struct nl_msg *msg;
+	struct rtmsg rtm = {
+		.rtm_family = AF_INET6,
+		.rtm_dst_len = prefixlen,
+		.rtm_src_len = 0,
+		.rtm_table = RT_TABLE_MAIN,
+		.rtm_protocol = (add ? RTPROT_STATIC : RTPROT_UNSPEC),
+		.rtm_scope = (add ? (gw ? RT_SCOPE_UNIVERSE : RT_SCOPE_LINK) : RT_SCOPE_NOWHERE),
+		.rtm_type = (add ? RTN_UNICAST : RTN_UNSPEC),
+	};
+	int ret = 0;
+
+	msg = nlmsg_alloc_simple(add ? RTM_NEWROUTE : RTM_DELROUTE,
+					add ? NLM_F_CREATE | NLM_F_REPLACE : 0);
+	if (!msg)
+		return -1;
+
+	nlmsg_append(msg, &rtm, sizeof(rtm), 0);
+
+	nla_put(msg, RTA_DST, sizeof(*addr), addr);
+	nla_put_u32(msg, RTA_OIF, iface->ifindex);
+	nla_put_u32(msg, RTA_PRIORITY, metric);
+
+	if (gw)
+		nla_put(msg, RTA_GATEWAY, sizeof(*gw), gw);
+
+	ret = nl_send_auto_complete(rtnl_socket, msg);
+	nlmsg_free(msg);
+
+	if (ret < 0)
+		return ret;
+
+	return nl_wait_for_ack(rtnl_socket);
+}
+
+
+int netlink_setup_proxy_neigh(const struct in6_addr *addr,
+		const struct interface *iface, const bool add)
+{
+	struct nl_msg *msg;
+	struct ndmsg ndm = {
+		.ndm_family = AF_INET6,
+		.ndm_flags = NTF_PROXY,
+		.ndm_ifindex = iface->ifindex,
+	};
+	int ret = 0, flags = NLM_F_REQUEST;
+
+	if (add)
+		flags |= NLM_F_REPLACE | NLM_F_CREATE;
+
+	msg = nlmsg_alloc_simple(add ? RTM_NEWNEIGH : RTM_DELNEIGH, flags);
+	if (!msg)
+		return -1;
+
+	nlmsg_append(msg, &ndm, sizeof(ndm), 0);
+
+	nla_put(msg, NDA_DST, sizeof(*addr), addr);
+
+	ret = nl_send_auto_complete(rtnl_socket, msg);
+	nlmsg_free(msg);
+
+	if (ret < 0)
+		return ret;
+
+	return nl_wait_for_ack(rtnl_socket);
+}
+
+
+int netlink_setup_addr(struct odhcpd_ipaddr *addr,
+		const struct interface *iface, const bool v6,
+		const bool add)
+{
+	struct nl_msg *msg;
+	struct ifaddrmsg ifa = {
+		.ifa_family = v6 ? AF_INET6 : AF_INET,
+		.ifa_prefixlen = addr->prefix,
+		.ifa_flags = 0,
+		.ifa_scope = 0,
+		.ifa_index = iface->ifindex, };
+	int ret = 0, flags = NLM_F_REQUEST;
+
+	if (add)
+		flags |= NLM_F_REPLACE | NLM_F_CREATE;
+
+	msg = nlmsg_alloc_simple(add ? RTM_NEWADDR : RTM_DELADDR, 0);
+	if (!msg)
+		return -1;
+
+	nlmsg_append(msg, &ifa, sizeof(ifa), flags);
+	nla_put(msg, IFA_LOCAL, v6 ? 16 : 4, &addr->addr);
+	if (v6) {
+		struct ifa_cacheinfo cinfo = {	.ifa_prefered = 0xffffffffU,
+						.ifa_valid = 0xffffffffU,
+						.cstamp = 0,
+						.tstamp = 0 };
+		time_t now = odhcpd_time();
+
+		if (addr->preferred) {
+			int64_t preferred = addr->preferred - now;
+			if (preferred < 0)
+				preferred = 0;
+			else if (preferred > UINT32_MAX)
+				preferred = UINT32_MAX;
+
+			cinfo.ifa_prefered = preferred;
+		}
+
+		if (addr->valid) {
+			int64_t valid = addr->valid - now;
+			if (valid <= 0) {
+				nlmsg_free(msg);
+				return -1;
+			}
+			else if (valid > UINT32_MAX)
+				valid = UINT32_MAX;
+
+			cinfo.ifa_valid = valid;
+		}
+
+		nla_put(msg, IFA_CACHEINFO, sizeof(cinfo), &cinfo);
+
+		nla_put_u32(msg, IFA_FLAGS, IFA_F_NOPREFIXROUTE);
+	} else {
+		if (addr->broadcast.s_addr)
+			nla_put_u32(msg, IFA_BROADCAST, addr->broadcast.s_addr);
+	}
+
+	ret = nl_send_auto_complete(rtnl_socket, msg);
+	nlmsg_free(msg);
+
+	if (ret < 0)
+		return ret;
+
+	return nl_wait_for_ack(rtnl_socket);
+}