cmm/src/neighbor_resolution.c

/*
 *
 *  Copyright (C) 2007 Mindspeed Technologies, Inc.
 *
 * This program is free software; you can redistribute it 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.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#include <libnetfilter_conntrack/libnetfilter_conntrack.h>
#include <libnetfilter_conntrack/libnetfilter_conntrack_tcp.h>


#undef NLMSG_TAIL
#include <net/if.h>
#include <net/if_arp.h>
#include <linux/if_packet.h>
#include <linux/if_ether.h>
#include <netinet/icmp6.h>

#include "cmm.h"
#include "itf.h"
#include "forward_engine.h"
#include "neighbor_resolution.h"

extern pthread_mutex_t tnlMutex;

struct list_head neigh_table[2 * NEIGHBOR_HASH_TABLE_SIZE];
struct list_head neigh_table_by_mac[NEIGHBOR_HASH_TABLE_SIZE];
struct list_head neigh_state_table;

pthread_mutex_t neighMutex = PTHREAD_MUTEX_INITIALIZER;

static struct neighReq *neighReqHead = NULL;


static int cmmNeighborNetlinkLookupAllFilter(const struct sockaddr_nl *nladdr, struct nlmsghdr *nlh, void *arg)
{
	int ifindex = *(int *)arg;
	struct NeighborEntry *neigh;
	struct ndmsg *ndm;
	struct rtattr *attr;

	if (nlh->nlmsg_type != RTM_NEWNEIGH) {
		cmm_print(DEBUG_ERROR, "%s::%d: unexpected netlink message(%d)\n",
					 __func__, __LINE__, nlh->nlmsg_type);

		goto out;
	}

	ndm = NLMSG_DATA(nlh);

	if (ndm->ndm_state & NUD_NOARP)
		goto out;

	if (ndm->ndm_ifindex != ifindex)
		goto out;

	attr = cmm_get_rtattr(NDA_RTA(ndm), NDA_PAYLOAD(nlh), NDA_DST);
	if (!attr) {
		cmm_print(DEBUG_ERROR, "%s::%d: rtnetlink message missing daddr\n", __func__, __LINE__);
		goto out;
	}

	/* If an entry already exists then skip update,
	it will be done through the listner thread. This is to avoid calling the ARP/Neighbor state machine from here */
	neigh = __cmmNeighFind(ndm->ndm_family, RTA_DATA(attr), ifindex);
	if ((!neigh) && !itf_match_src_ipaddr(ifindex, ndm->ndm_family, RTA_DATA(attr))){
		neigh = __cmmNeighAdd(ndm->ndm_family, RTA_DATA(attr), ifindex);
		if (!neigh) {
			cmm_print(DEBUG_ERROR, "%s::%d: __cmmNeighAdd() failed\n", __func__, __LINE__);
			goto out;
		}
	}
	else
		goto out;

	/* Putting data in ArpEntry */
	neigh->state = ndm->ndm_state;

	if (neigh->state & NUD_VALID) {
		int key;

		attr = cmm_get_rtattr(NDA_RTA(ndm), NDA_PAYLOAD(nlh), NDA_LLADDR);

		if (attr)
			memcpy(neigh->macAddr, RTA_DATA(attr), RTA_PAYLOAD(attr));
		else
			memset(neigh->macAddr, 0, ETH_ALEN);

		key = HASH_MAC(neigh->macAddr);
		list_add(&neigh_table_by_mac[key], &neigh->list_by_mac);
	}
	else
		memset(neigh->macAddr, 0, ETH_ALEN);

out:
	return RTNL_CB_CONTINUE;
}

static int cmmNeighborNetlinkLookupAll(int family, int ifindex)
{
	struct rtnl_handle rth;
	struct ndmsg ndm = {
		.ndm_family = family,
		.ndm_ifindex = 0,
		.ndm_state = 0,
		.ndm_flags = 0,
		.ndm_type = 0,
	};

	cmm_print(DEBUG_INFO, "%s\n", __func__);

	if (cmm_rtnl_open(&rth, 0) < 0) {
		cmm_print(DEBUG_ERROR, "%s::%d: netlink socket() %s\n", __func__, __LINE__, strerror(errno));
		goto err0;
	}

	if (cmm_rtnl_dump_request(&rth, RTM_GETNEIGH, &ndm, sizeof(struct ndmsg)) < 0)
		goto err1;

	cmm_rtnl_listen(&rth, cmmNeighborNetlinkLookupAllFilter, &ifindex);

	cmm_rtnl_close(&rth);

	return 0;

err1:
	cmm_rtnl_close(&rth);

err0:
	return -1;
}




int cmmNeighAddSolicitQ(int family, int ifindex, unsigned int *dst_ip, unsigned char *dst_mac)
{
	struct neighReq *n;

	n = (struct neighReq *)malloc(sizeof(struct neighReq));
	if (!n) {
		return -1;
	}
	
	n->family = family;
	n->ifindex = ifindex;
	if (family == AF_INET)
		n->dst_ip[0] = *dst_ip;
	else
		memcpy((unsigned char *)n->dst_ip, (unsigned char *)dst_ip, 16);
	
	if (dst_mac != NULL) {
		memcpy(n->dst_mac, dst_mac, 6);
		n->dst_mac_null=0;
	}
	else {
		n->dst_mac_null=1;
	}

	if (neighReqHead != NULL)
		n->next = neighReqHead;
	else
		n->next = NULL;

	neighReqHead = n;
	
	return 0;
}

void cmmNeighSendSolicitQ(void)
{
	struct neighReq *n, *next;

	if (neighReqHead == NULL)
		return;
	 
	for(n = neighReqHead; n != NULL; n = next) {

		if (n->family == AF_INET) {
			cmmArpRequest(n->ifindex, n->dst_ip[0], 
						n->dst_mac_null ? NULL : n->dst_mac);
		}
		else  {
			cmmNeighborSolicitation(n->ifindex, n->dst_ip, 
						n->dst_mac_null ? NULL : n->dst_mac);
		}
		
		next = n->next;
		free(n);
	}
	neighReqHead = NULL;

	return;
}





#define MULTICAST_SOLICITED_NODE "FF02::1:FF00:0000"

int cmmNeighborSolicitation(int ifindex, unsigned int *dst_ip, unsigned char *dst_mac)
{
	struct sockaddr_in6 sockaddr;
	struct __attribute__((packed)) {
		struct nd_neighbor_solicit hdr;
		uint8_t nd_opt_type;
		uint8_t nd_opt_len;
		unsigned char src_mac[ETH_ALEN];
	} neighbor;
	int sockopt;
	unsigned int multi_addr[4];
	int fd;
	int len;
	int rc = -1;

	/* dst_mac is NULL for multicast solicitations */
	if(dst_mac == NULL)
		inet_pton(AF_INET6, MULTICAST_SOLICITED_NODE, multi_addr);

	fd = socket (AF_INET6, SOCK_RAW, IPPROTO_ICMPV6);
	if (fd < 0) {
		cmm_print(DEBUG_ERROR, "%s::%d: socket() %s\n", __func__, __LINE__, strerror(errno));
		goto out;
	}

	memset(&sockaddr, 0, sizeof(struct sockaddr_in6));

	sockaddr.sin6_family = AF_INET6;
	sockaddr.sin6_scope_id = ifindex;

	if (itf_get_ipaddr(ifindex, AF_INET6, RT_SCOPE_LINK, (unsigned int *)&sockaddr.sin6_addr.s6_addr32, dst_ip) < 0) {
		cmm_print(DEBUG_ERROR, "%s::%d: itf_get_ipaddr(%d) failed\n", __func__, __LINE__, ifindex);
		goto close;
	}
	

	if (bind(fd, (struct sockaddr *)&sockaddr, sizeof(sockaddr)) < 0) {
		cmm_print(DEBUG_ERROR, "%s::%d: bind() %s\n", __func__, __LINE__, strerror(errno));
		goto close;
	}

	memset(&sockaddr, 0, sizeof(struct sockaddr_in6));
	sockaddr.sin6_family = AF_INET6;
	if(dst_mac == NULL)	{
		memcpy(sockaddr.sin6_addr.s6_addr, multi_addr, sizeof(multi_addr));
		memcpy(sockaddr.sin6_addr.s6_addr + 13, (unsigned char *)dst_ip + 13, 3);
	}
	else {
		memcpy(sockaddr.sin6_addr.s6_addr, (unsigned char *)dst_ip, 16);
	}
	
	memset(&neighbor.hdr, 0, sizeof(struct nd_neighbor_solicit));
	neighbor.hdr.nd_ns_type = ND_NEIGHBOR_SOLICIT;
	memcpy(&neighbor.hdr.nd_ns_target, dst_ip, 16);

	neighbor.nd_opt_type = ND_OPT_SOURCE_LINKADDR;
	neighbor.nd_opt_len = 1; /* 8 bytes */

	if (itf_get_macaddr(ifindex, neighbor.src_mac) < 0) {
		cmm_print(DEBUG_ERROR, "%s::%d: itf_get_macaddr(%d) failed\n", __func__, __LINE__, ifindex);
		goto close;
	}

	sockopt = 255;
	if(dst_mac == NULL)	{
		if (setsockopt(fd, SOL_IPV6, IPV6_MULTICAST_HOPS, (char *) &sockopt, sizeof(sockopt)) < 0) {
			cmm_print(DEBUG_ERROR, "%s::%d: setsockopt() %s\n", __func__, __LINE__, strerror(errno));
			goto close;
		}
	}
	else {
		if (setsockopt(fd, SOL_IPV6, IPV6_UNICAST_HOPS, (char *) &sockopt, sizeof(sockopt)) < 0) {
			cmm_print(DEBUG_ERROR, "%s::%d: setsockopt() %s\n", __func__, __LINE__, strerror(errno));
			goto close;
		}
	}

	len = sizeof(neighbor);
	if (sendto(fd, &neighbor, len, 0, (struct sockaddr *) &sockaddr, sizeof(sockaddr)) < len) {
		cmm_print(DEBUG_ERROR, "%s::%d: sendto() %s\n", __func__, __LINE__, strerror(errno));
		goto close;
	}

	rc = 0;

close:
	close(fd);
out:
	return rc;
}

int cmmArpRequest(int ifindex, unsigned int dst_ip, unsigned char *dst_mac)
{
	struct sockaddr_ll sockaddr;
	struct __attribute__((packed)) {
		struct arphdr ah;
		unsigned char src_mac[ETH_ALEN];
		unsigned int src_ip;
		unsigned char dst_mac[ETH_ALEN];
		unsigned int dst_ip;
	} arp;
	unsigned int src_ip;
	unsigned char src_mac[ETH_ALEN];
	int fd;
	int len;
	int rc = -1;

	fd = socket(PF_PACKET, SOCK_DGRAM, 0);
	if (fd < 0) {
		cmm_print(DEBUG_ERROR, "%s::%d: socket() %s\n", __func__, __LINE__, strerror(errno));
		goto out;
	}

	memset(&sockaddr, 0, sizeof(struct sockaddr_ll));
	sockaddr.sll_family = AF_PACKET;
	sockaddr.sll_ifindex = ifindex;
	sockaddr.sll_protocol = htons(ETH_P_ARP);

	if (bind(fd, (struct sockaddr *) &sockaddr, sizeof(struct sockaddr_ll)) < 0) {
		cmm_print(DEBUG_ERROR, "%s::%d: bind() %s\n", __func__, __LINE__, strerror(errno));
		goto close;
	}

	memset(&sockaddr, 0, sizeof(struct sockaddr_ll));
	sockaddr.sll_family = AF_PACKET;
	sockaddr.sll_ifindex = ifindex;
	sockaddr.sll_protocol = htons(ETH_P_ARP);
	sockaddr.sll_halen = ETH_ALEN;

	if (itf_get_ipaddr(ifindex, AF_INET, RT_SCOPE_UNIVERSE, &src_ip, &dst_ip) < 0) {
		cmm_print(DEBUG_ERROR, "%s::%d: itf_get_ipaddr(%d) failed\n", __func__, __LINE__, ifindex);
		goto close;
	}

	if (itf_get_macaddr(ifindex, src_mac) < 0) {
		cmm_print(DEBUG_ERROR, "%s::%d: itf_get_macaddr(%d) failed\n", __func__, __LINE__, ifindex);
		goto close;
	}

	if (!dst_mac)
		/* broadcast */
		memset(sockaddr.sll_addr, 0xFF, ETH_ALEN);
	else
		/* unicast */
		memcpy(sockaddr.sll_addr, dst_mac, ETH_ALEN);

	arp.ah.ar_hrd = htons(ARPHRD_ETHER);
	arp.ah.ar_pro = htons(ETH_P_IP);
	arp.ah.ar_hln = ETH_ALEN;
	arp.ah.ar_pln = 4;
	arp.ah.ar_op = htons(ARPOP_REQUEST);

	memcpy(arp.src_mac, src_mac, ETH_ALEN);
	memcpy(&arp.src_ip, &src_ip, 4);

	if (!dst_mac)
		memset(arp.dst_mac, 0, ETH_ALEN);
	else
		memcpy(arp.dst_mac, sockaddr.sll_addr, ETH_ALEN);

	memcpy(&arp.dst_ip, &dst_ip, 4);

	len = sizeof(arp);
	if (sendto(fd, &arp, len, 0, (struct sockaddr *) &sockaddr, sizeof(struct sockaddr_ll)) < len) {
		cmm_print(DEBUG_ERROR, "%s::%d: sendto() %s\n", __func__, __LINE__, strerror(errno));
		goto close;
	}

	rc = 0;

close:
	close(fd);
out:
	return rc;
}

/*****************************************************************
* __cmmNeighUpdateAllMacs
*
*
******************************************************************/
void __cmmNeighUpdateAllMacs(int ifindex, unsigned char *macAddr, int port)
{
	struct NeighborEntry *neigh;
	struct list_head *entry;
	int key;

	key = HASH_MAC(macAddr);

	entry = list_first(&neigh_table_by_mac[key]);

	while (entry != &neigh_table_by_mac[key])
	{
		neigh = container_of(entry, struct NeighborEntry, list_by_mac);

		if ((neigh->ifindex == ifindex) &&
		    !memcmp(neigh->macAddr, macAddr, ETH_ALEN))
			neigh->port = port;

		entry = list_next(entry);
	}
}

/*****************************************************************
* __cmmNeighFind
*
*
******************************************************************/
struct NeighborEntry *__cmmNeighFind(int family, const unsigned int *ipAddr, int ifindex)
{
	struct NeighborEntry *neigh;
	struct list_head *entry;
	char buf[INET6_ADDRSTRLEN];
	int key;
	int ipAddrLen = IPADDRLEN(family);

	cmm_print(DEBUG_INFO, "%s: Neighbor(%d, %s)\n", __func__, ifindex, inet_ntop(family, ipAddr, buf, sizeof(buf)));

	key = HASH_NEIGHBOR(family, ipAddr);

	entry = list_first(&neigh_table[key]);

	while (entry != &neigh_table[key])
	{
		neigh = container_of(entry, struct NeighborEntry, list);
		if (!memcmp(neigh->ipAddr, ipAddr, ipAddrLen) && neigh->ifindex == ifindex)
			goto found;

		entry = list_next(entry);
	}

	neigh = NULL;

found:

	return neigh;
}


/*****************************************************************
* __cmmNeighRemove
*
*
******************************************************************/

/* NOTE: The neighMutex must be locked by the caller of this routine. */

void __cmmNeighRemove(struct NeighborEntry *neigh)
{
	char buf[INET6_ADDRSTRLEN];

	list_del(&neigh->list);

	if (neigh->state & NUD_VALID)
		list_del(&neigh->list_by_mac);

	if (neigh->flags & NEEDS_SOLICIT)
		list_del(&neigh->list_by_state);
	
	cmm_print(DEBUG_INFO, "%s: Neighbor(%d, %s) removed\n", __func__, neigh->ifindex, inet_ntop(neigh->family, neigh->ipAddr, buf, sizeof(buf)));

	free(neigh);
}

/*****************************************************************
* __cmmNeighPut
*
*
******************************************************************/
void __cmmNeighPut(struct NeighborEntry *neigh)
{
	char buf[INET6_ADDRSTRLEN];

	cmm_print(DEBUG_INFO, "%s: Neighbor(%d, %s) put\n", __func__, neigh->ifindex, inet_ntop(neigh->family, neigh->ipAddr, buf, sizeof(buf)));

	neigh->count--;

	if (neigh->count <= 0)
	{
		__cmmNeighRemove(neigh);
	}
}


/*****************************************************************
* __cmmNeighAdd
*
*
******************************************************************/
struct NeighborEntry *__cmmNeighAdd(int family, const unsigned int *ipAddr, int ifindex)
{
	struct NeighborEntry *neigh;
	char buf[INET6_ADDRSTRLEN];
	int key;

	neigh = malloc(sizeof(struct NeighborEntry));
	if (!neigh)
	{
		cmm_print(DEBUG_ERROR, "%s::%d: malloc() failed\n", __func__, __LINE__);
		goto err0;
	}

	memset(neigh, 0, sizeof(struct NeighborEntry));

	neigh->count = 0;
	neigh->port = -1;
	neigh->nr_probes = 0;
	neigh->ifindex = ifindex;
	neigh->ipAddrLen = IPADDRLEN(family);
	neigh->family = family;
	memcpy(neigh->ipAddr, ipAddr, neigh->ipAddrLen);

	key = HASH_NEIGHBOR(family, ipAddr);

	list_add(&neigh_table[key], &neigh->list);

	cmm_print(DEBUG_INFO, "%s: Neighbor(%d, %s) added\n", __func__, ifindex, inet_ntop(family, ipAddr, buf, sizeof(buf)));

	return neigh;

err0:
	return NULL;
}


/*****************************************************************
* __cmmNeighGet
*
*
******************************************************************/
struct NeighborEntry *__cmmNeighGet(int family, const unsigned int *ipAddr, int ifindex)
{
	struct NeighborEntry *neigh;

	neigh = __cmmNeighFind(family, ipAddr, ifindex);
	if (!neigh)
	{
		if (cmmNeighborNetlinkLookupAll(family, ifindex) < 0)
		{
			cmm_print(DEBUG_ERROR, "%s::%d: cmmNeighborNetlinkLookupAll() failed\n", __func__, __LINE__);
			goto err;
		}

		neigh = __cmmNeighFind(family, ipAddr, ifindex);
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,19,0)
/* 
   In 3.19 kernel, neighbor entry in linux neighbor cache is not created during the creation of route entry in linux
   route cache as was done in previous versions. If neighbor entry is not present in linux during route look up in CMM,
   then neigbhor is not attached to CMM route and the subsequent neighbor creation event from linux is also ignored by CMM.
   As a result all the connections using this CMM route are not fast forwarded.
   To resolve this, if neighbor entry is not present in linux then a dummy neighbor is created in CMM. This dummy neighbor
   will be updated when the CMM receives the neighbor creation event
*/
		if(!neigh)
			neigh = __cmmNeighAdd(family, ipAddr, ifindex);
#endif
		if (!neigh)
			goto err;
	}

	neigh->count++;

	return neigh;

err:
	return NULL;
}


/*****************************************************************
* cmmNeighShow
*
*
******************************************************************/
int cmmNeighShow(struct cli_def * cli, char *command, char *argv[], int argc)
{
	int i;
	struct NeighborEntry *temp;
	struct list_head *entry;
	char addr_buf[INET6_ADDRSTRLEN];
	char mac_buf[MAC_ADDRSTRLEN];
	char ifname[IFNAMSIZ];
	int count;

	cli_print(cli, "IPv4 ARP:");

	count = 0;

	for (i = 0; i < NEIGHBOR_HASH_TABLE_SIZE; i++)
	{
		__pthread_mutex_lock(&neighMutex);

		for (entry = list_first(&neigh_table[i]); entry != &neigh_table[i]; entry = list_next(entry))
		{
			temp = container_of(entry, struct NeighborEntry, list);

			cli_print(cli, "IP addr: %s --> MAC addr: %s If: %s, Port:%d, state: %x, Count: %d",
				inet_ntop(AF_INET, temp->ipAddr, addr_buf, sizeof(addr_buf)),
				mac_ntop(temp->macAddr, mac_buf, sizeof(mac_buf)),
				if_indextoname(temp->ifindex, ifname),
				temp->port,
				temp->state,
				temp->count);

			count++;
		}
		__pthread_mutex_unlock(&neighMutex);
	}

	cli_print(cli, "Total ARP Entries: %d\n", count);

	cli_print(cli, "IPv6 Neighbor:");

	count = 0;

	for (i = NEIGHBOR_HASH_TABLE_SIZE; i < 2 * NEIGHBOR_HASH_TABLE_SIZE; i++)
	{
		__pthread_mutex_lock(&neighMutex);
		for (entry = list_first(&neigh_table[i]); entry != &neigh_table[i]; entry = list_next(entry))
		{

			temp = container_of(entry, struct NeighborEntry, list);

			cli_print(cli, "IP addr: %s --> MAC addr: %s If: %s, Port: %d, state: %x, Count: %d",
				inet_ntop(AF_INET6, temp->ipAddr, addr_buf, sizeof(addr_buf)),
				mac_ntop(temp->macAddr, mac_buf, sizeof(mac_buf)),
				if_indextoname(temp->ifindex, ifname),
				temp->port,
				temp->state,
				temp->count);

				count++;
		}
		__pthread_mutex_unlock(&neighMutex);
	}

	cli_print(cli, "Total Neighbor Entries: %d\n", count);

	return CLI_OK;
}


/*****************************************************************
* cmmNeighborResolved
* 
*
******************************************************************/
static void __cmmNeighborResolved(FCI_CLIENT *fci_handle, struct NeighborEntry *neigh)
{
	/* Process conntrack entries that use this neighbor */
	struct RtEntry *route;
	struct list_head *entry;
	int key;

	/* Force lookup of bridge port */
	neigh->port = -1;

	key = HASH_MAC(neigh->macAddr);
	list_add(&neigh_table_by_mac[key], &neigh->list_by_mac);

	key = HASH_NEIGHBOR(neigh->family, neigh->ipAddr);

	entry = list_first(&rt_table_by_gw_ip[key]);
	while (entry != &rt_table_by_gw_ip[key])
	{
		route = container_of(entry, struct RtEntry, list_by_gw_ip);
		entry = list_next(entry);

		if (route->neighEntry != neigh)
			continue;

		/* Force lookup of bridge port */
		route->flags |= CHECK_BRIDGE_PORT;

		__cmmCtUpdateWithRoute(fci_handle, route);

		__cmmTunnelUpdateWithRoute(fci_handle, route);

		__cmmSocketUpdateWithRoute(fci_handle, route);
		/* Process SA entries that use this neighbour */
		__cmmSAUpdateWithRoute(fci_handle, route);
	}
}

/*****************************************************************
* cmmNeighborUnresolved
* 
*
******************************************************************/
static void __cmmNeighborUnresolved(FCI_CLIENT *fci_handle, struct NeighborEntry *neigh)
{
	/* Process conntrack entries that use this neighbor */
	struct RtEntry *route;
	struct list_head *entry;
	int key;

	cmm_print(DEBUG_INFO, "%s: Remove ARP/Neighbor entry\n", __func__);

	list_del(&neigh->list_by_mac);

	/* Reset bridge port information, if any */
	neigh->port = -1;

	key = HASH_NEIGHBOR(neigh->family, neigh->ipAddr);

	entry = list_first(&rt_table_by_gw_ip[key]);
	while (entry != &rt_table_by_gw_ip[key])
	{
		route = container_of(entry, struct RtEntry, list_by_gw_ip);
		entry = list_next(entry);

		if (route->neighEntry != neigh)
			continue;

		/* Force lookup of bridge port */
		route->flags |= CHECK_BRIDGE_PORT;

		__cmmCtUpdateWithRoute(fci_handle, route);

		__cmmTunnelUpdateWithRoute(fci_handle, route);

		__cmmSocketUpdateWithRoute(fci_handle, route);
		/* Process SA entries that use this neighbour */
		__cmmSAUpdateWithRoute(fci_handle, route);
	}
}

/*****************************************************************
* cmmNeighborUpdate
* 
*
******************************************************************/
static int cmmNeighborUpdate(struct cmm_ct *ctx, const struct sockaddr_nl *who, struct nlmsghdr *n)
{
	char buf[INET6_ADDRSTRLEN];
	struct ndmsg *r = NLMSG_DATA(n);
	struct rtattr * tb [NDA_MAX + 1];
	struct NeighborEntry *neigh;
	unsigned int *ipAddr;
	unsigned char *macAddr;
	unsigned int macAddrLen;
	unsigned short old_state;

	/*Parse the message*/
	cmm_parse_rtattr(tb, NDA_MAX, NDA_RTA(r), NDA_PAYLOAD(n));

	/* Check if the event can interrest us*/
	if (!tb[NDA_DST])
		return 0;

	if (r->ndm_state & NUD_NOARP)
		return 0;

	ipAddr = RTA_DATA(tb[NDA_DST]);

	if (tb[NDA_LLADDR])
	{
		macAddr = RTA_DATA(tb[NDA_LLADDR]);
		macAddrLen = RTA_PAYLOAD(tb[NDA_LLADDR]);
	}
	else
	{
		macAddr = NULL;
		macAddrLen = 0;
	}

	/*Get the IP address in ascii*/
	inet_ntop(r->ndm_family, ipAddr, buf, INET6_ADDRSTRLEN);
	cmm_print(DEBUG_INFO, "%s: %s, state=%x\n", __func__, buf, r->ndm_state);

	/*Try to find a corresponding entry in the ARP table*/
	__pthread_mutex_lock(&itf_table.lock);
	__pthread_mutex_lock(&ctMutex);
	__pthread_mutex_lock(&rtMutex);
	__pthread_mutex_lock(&neighMutex);
	__pthread_mutex_lock(&flowMutex);

	neigh = __cmmNeighFind(r->ndm_family, ipAddr, r->ndm_ifindex);
	if (!neigh)
		goto out;

	/* Update local entry */
	old_state = neigh->state;
	neigh->state = r->ndm_state;
	cmm_print(DEBUG_INFO, "%s: old state = 0x%0x new state = 0x%0x\n", __func__, old_state, neigh->state);

	if((r->ndm_state & NUD_REACHABLE) && (neigh->flags & NEEDS_SOLICIT))
	{
		neigh->flags &= ~NEEDS_SOLICIT;
		neigh->nr_probes = 0;
		list_del(&neigh->list_by_state);
		cmm_print(DEBUG_INFO, "%s: Deleted Entry in Neighbor by state list \n", __func__);
	}

	//Neigh entries which are used by atleast one conntrack are added to state list
	if ((r->ndm_state & NUD_STALE) && (!(neigh->flags & NEEDS_SOLICIT)) && neigh->count > 0)
	{
		neigh->flags |= NEEDS_SOLICIT;
		list_add(&neigh_state_table, &neigh->list_by_state);
		cmm_print(DEBUG_INFO, "%s: Added Entry in Neighbor by state list \n", __func__);
	}

	/* Neigh entries which are not used by any conntrack are removed from CMM when
	the corresponding neigh entry is deleted by Kernel. */
	if(n->nlmsg_type == RTM_DELNEIGH && neigh->count <= 0)
	{
		__cmmNeighRemove(neigh);
		goto out;
	}

	/*In those states, the MAC address is usable*/
	if (r->ndm_state & NUD_VALID)
	{
		cmm_print(DEBUG_INFO, "%s: Update ARP/Neighbor entry\n", __func__);

		memcpy(neigh->macAddr, macAddr, macAddrLen);
		if (old_state & NUD_VALID)
			list_del(&neigh->list_by_mac);
		__cmmNeighborResolved(ctx->fci_handle, neigh);
	}
	else
	{
		memset(neigh->macAddr, 0, ETH_ALEN);

		if (old_state & NUD_VALID)
			__cmmNeighborUnresolved(ctx->fci_handle, neigh);
	}

out:
	__pthread_mutex_unlock(&flowMutex);
	__pthread_mutex_unlock(&neighMutex);
	__pthread_mutex_unlock(&rtMutex);
	__pthread_mutex_unlock(&ctMutex);
	__pthread_mutex_unlock(&itf_table.lock);

	return 0;
}


/*****************************************************************
* cmmNeighThread
*
* Function that sends neighbor soliciations
*
******************************************************************/
int cmmNeighSendSolicit(void)
{
	struct NeighborEntry *neigh;
	struct list_head *entry;
	struct list_head *next;

	__pthread_mutex_lock(&neighMutex);
	
	for (entry = list_first(&neigh_state_table); entry != &neigh_state_table; entry = next)
	{
		next = list_next(entry);
		
		neigh = container_of(entry, struct NeighborEntry, list_by_state);

		if(neigh->nr_probes < MAX_UCAST_SOLICIT )
		{
			if(cmmNeighAddSolicitQ(neigh->family, neigh->ifindex,
						neigh->ipAddr, neigh->macAddr) == 0)
				neigh->nr_probes++;
		}
		else if ((neigh->nr_probes >= MAX_UCAST_SOLICIT) && 
				(neigh->nr_probes < (MAX_UCAST_SOLICIT + MAX_MCAST_SOLICIT)))
		{
			if(cmmNeighAddSolicitQ(neigh->family, neigh->ifindex,
						neigh->ipAddr, NULL) == 0)
				neigh->nr_probes++;
		}
		else
		{
			neigh->flags &= ~NEEDS_SOLICIT;
			neigh->nr_probes = 0;
			list_del(&neigh->list_by_state);
			cmm_print(DEBUG_INFO, "%s: Deleted Entry in Neighbor by state list \n", __func__);
		}
		
	}

	__pthread_mutex_unlock(&neighMutex);

	cmmNeighSendSolicitQ();

	return 0;
}

/*****************************************************************
* cmmNeighborGet
* 
*
******************************************************************/
static int cmmNeighborGet(struct cmm_ct *ctx, const struct sockaddr_nl *who, struct nlmsghdr *n)
{
	struct ndmsg *r = NLMSG_DATA(n);
	char tab6[INET6_ADDRSTRLEN];
	char ifname[IFNAMSIZ];
	struct rtattr * tb [NDA_MAX + 1];

	/* ARP request immediately done by CMM as Kernel waits 1 seconds before sending it */	
	
	/*Parse the message*/
        cmm_parse_rtattr(tb, NDA_MAX, NDA_RTA(r), NDA_PAYLOAD(n));

	inet_ntop(r->ndm_family, RTA_DATA(tb[NDA_DST]), tab6, INET6_ADDRSTRLEN);
	cmm_print(DEBUG_INFO, "%s: %s(%s), state=%x\n", __func__, tab6, if_indextoname(r->ndm_ifindex, ifname), r->ndm_state);

	/*IPv4 Neighbor*/
	if (r->ndm_family == AF_INET)
	{
		cmmArpRequest(r->ndm_ifindex, *(unsigned int *)(RTA_DATA(tb[NDA_DST])), NULL);
	}
	else if(r->ndm_family == AF_INET6)
	{
		cmmNeighborSolicitation(r->ndm_ifindex, (unsigned int *)(RTA_DATA(tb[NDA_DST])), NULL);
	}

	// Return, 
	return RTNL_CB_CONTINUE;
}


/*****************************************************************
* cmmRtnlNeigh
* 
*
******************************************************************/
int cmmRtnlNeigh(const struct sockaddr_nl *who, struct nlmsghdr *nlh, void *arg)
{
	struct cmm_ct *ctx = arg;

	switch (nlh->nlmsg_type) {
	case RTM_GETNEIGH:
		cmmNeighborGet(ctx, who, nlh);
		break;

	case RTM_NEWNEIGH:
	case RTM_DELNEIGH:
		cmmNeighborUpdate(ctx, who, nlh);
		break;

	default:
		cmm_print(DEBUG_ERROR, "%s: unsupported NEIGH netlink message %x\n", __func__, nlh->nlmsg_type);
		break;
	}

	return RTNL_CB_CONTINUE;
}