path: root/eigrpd/eigrp_packet.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * EIGRP General Sending and Receiving of EIGRP Packets.
 * Copyright (C) 2013-2014
 * Authors:
 *   Donnie Savage
 *   Jan Janovic
 *   Matej Perina
 *   Peter Orsag
 *   Peter Paluch
 */

#include <zebra.h>

#include "frrevent.h"
#include "memory.h"
#include "linklist.h"
#include "vty.h"
#include "keychain.h"
#include "prefix.h"
#include "if.h"
#include "table.h"
#include "sockunion.h"
#include "stream.h"
#include "log.h"
#include "sockopt.h"
#include "checksum.h"
#include "md5.h"
#include "sha256.h"
#include "lib_errors.h"

#include "eigrpd/eigrp_structs.h"
#include "eigrpd/eigrpd.h"
#include "eigrpd/eigrp_interface.h"
#include "eigrpd/eigrp_neighbor.h"
#include "eigrpd/eigrp_packet.h"
#include "eigrpd/eigrp_zebra.h"
#include "eigrpd/eigrp_vty.h"
#include "eigrpd/eigrp_dump.h"
#include "eigrpd/eigrp_macros.h"
#include "eigrpd/eigrp_network.h"
#include "eigrpd/eigrp_topology.h"
#include "eigrpd/eigrp_fsm.h"
#include "eigrpd/eigrp_errors.h"

DEFINE_MTYPE_STATIC(EIGRPD, EIGRP_FIFO,            "EIGRP FIFO");
DEFINE_MTYPE_STATIC(EIGRPD, EIGRP_PACKET,          "EIGRP Packet");
DEFINE_MTYPE_STATIC(EIGRPD, EIGRP_IPV4_INT_TLV,    "EIGRP IPv4 TLV");
DEFINE_MTYPE_STATIC(EIGRPD, EIGRP_SEQ_TLV,         "EIGRP SEQ TLV");
DEFINE_MTYPE_STATIC(EIGRPD, EIGRP_AUTH_TLV,        "EIGRP AUTH TLV");
DEFINE_MTYPE_STATIC(EIGRPD, EIGRP_AUTH_SHA256_TLV, "EIGRP SHA TLV");

/* Packet Type String. */
const struct message eigrp_packet_type_str[] = {
	{EIGRP_OPC_UPDATE, "Update"},
	{EIGRP_OPC_REQUEST, "Request"},
	{EIGRP_OPC_QUERY, "Query"},
	{EIGRP_OPC_REPLY, "Reply"},
	{EIGRP_OPC_HELLO, "Hello"},
	{EIGRP_OPC_IPXSAP, "IPX-SAP"},
	{EIGRP_OPC_PROBE, "Probe"},
	{EIGRP_OPC_ACK, "Ack"},
	{EIGRP_OPC_SIAQUERY, "SIAQuery"},
	{EIGRP_OPC_SIAREPLY, "SIAReply"},
	{0}};


static unsigned char zeropad[16] = {0};

/* Forward function reference*/
static struct stream *eigrp_recv_packet(struct eigrp *eigrp, int fd,
					struct interface **ifp,
					struct stream *s);
static int eigrp_verify_header(struct stream *s, struct eigrp_interface *ei,
			       struct ip *addr, struct eigrp_header *header);
static int eigrp_check_network_mask(struct eigrp_interface *ei,
				    struct in_addr mask);

static int eigrp_retrans_count_exceeded(struct eigrp_packet *ep,
					struct eigrp_neighbor *nbr)
{
	return 1;
}

int eigrp_make_md5_digest(struct eigrp_interface *ei, struct stream *s,
			  uint8_t flags)
{
	struct key *key = NULL;
	struct keychain *keychain;

	unsigned char digest[EIGRP_AUTH_TYPE_MD5_LEN];
	MD5_CTX ctx;
	uint8_t *ibuf;
	size_t backup_get, backup_end;
	struct TLV_MD5_Authentication_Type *auth_TLV;

	ibuf = s->data;
	backup_end = s->endp;
	backup_get = s->getp;

	auth_TLV = eigrp_authTLV_MD5_new();

	stream_set_getp(s, EIGRP_HEADER_LEN);
	stream_get(auth_TLV, s, EIGRP_AUTH_MD5_TLV_SIZE);
	stream_set_getp(s, backup_get);

	keychain = keychain_lookup(ei->params.auth_keychain);
	if (keychain)
		key = key_lookup_for_send(keychain);
	else {
		eigrp_authTLV_MD5_free(auth_TLV);
		return EIGRP_AUTH_TYPE_NONE;
	}

	memset(&ctx, 0, sizeof(ctx));
	MD5Init(&ctx);

	/* Generate a digest. Each situation needs different handling */
	if (flags & EIGRP_AUTH_BASIC_HELLO_FLAG) {
		MD5Update(&ctx, ibuf, EIGRP_MD5_BASIC_COMPUTE);
		MD5Update(&ctx, key->string, strlen(key->string));
		if (strlen(key->string) < 16)
			MD5Update(&ctx, zeropad, 16 - strlen(key->string));
	} else if (flags & EIGRP_AUTH_UPDATE_INIT_FLAG) {
		MD5Update(&ctx, ibuf, EIGRP_MD5_UPDATE_INIT_COMPUTE);
	} else if (flags & EIGRP_AUTH_UPDATE_FLAG) {
		MD5Update(&ctx, ibuf, EIGRP_MD5_BASIC_COMPUTE);
		MD5Update(&ctx, key->string, strlen(key->string));
		if (strlen(key->string) < 16)
			MD5Update(&ctx, zeropad, 16 - strlen(key->string));
		if (backup_end > (EIGRP_HEADER_LEN + EIGRP_AUTH_MD5_TLV_SIZE)) {
			MD5Update(&ctx,
				  ibuf + (EIGRP_HEADER_LEN
					  + EIGRP_AUTH_MD5_TLV_SIZE),
				  backup_end - 20
					  - (EIGRP_HEADER_LEN
					     + EIGRP_AUTH_MD5_TLV_SIZE));
		}
	}

	MD5Final(digest, &ctx);

	/* Append md5 digest to the end of the stream. */
	memcpy(auth_TLV->digest, digest, EIGRP_AUTH_TYPE_MD5_LEN);

	stream_set_endp(s, EIGRP_HEADER_LEN);
	stream_put(s, auth_TLV, EIGRP_AUTH_MD5_TLV_SIZE);
	stream_set_endp(s, backup_end);

	eigrp_authTLV_MD5_free(auth_TLV);
	return EIGRP_AUTH_TYPE_MD5_LEN;
}

int eigrp_check_md5_digest(struct stream *s,
			   struct TLV_MD5_Authentication_Type *authTLV,
			   struct eigrp_neighbor *nbr, uint8_t flags)
{
	MD5_CTX ctx;
	unsigned char digest[EIGRP_AUTH_TYPE_MD5_LEN];
	unsigned char orig[EIGRP_AUTH_TYPE_MD5_LEN];
	struct key *key = NULL;
	struct keychain *keychain;
	uint8_t *ibuf;
	size_t backup_end;
	struct TLV_MD5_Authentication_Type *auth_TLV;
	struct eigrp_header *eigrph;

	if (ntohl(nbr->crypt_seqnum) > ntohl(authTLV->key_sequence)) {
		zlog_warn(
			"interface %s: eigrp_check_md5 bad sequence %d (expect %d)",
			IF_NAME(nbr->ei), ntohl(authTLV->key_sequence),
			ntohl(nbr->crypt_seqnum));
		return 0;
	}

	eigrph = (struct eigrp_header *)s->data;
	eigrph->checksum = 0;

	auth_TLV = (struct TLV_MD5_Authentication_Type *)(s->data
							  + EIGRP_HEADER_LEN);
	memcpy(orig, auth_TLV->digest, EIGRP_AUTH_TYPE_MD5_LEN);
	memset(digest, 0, EIGRP_AUTH_TYPE_MD5_LEN);
	memset(auth_TLV->digest, 0, EIGRP_AUTH_TYPE_MD5_LEN);

	ibuf = s->data;
	backup_end = s->endp;

	keychain = keychain_lookup(nbr->ei->params.auth_keychain);
	if (keychain)
		key = key_lookup_for_send(keychain);

	if (!key) {
		zlog_warn(
			"Interface %s: Expected key value not found in config",
			nbr->ei->ifp->name);
		return 0;
	}

	memset(&ctx, 0, sizeof(ctx));
	MD5Init(&ctx);

	/* Generate a digest. Each situation needs different handling */
	if (flags & EIGRP_AUTH_BASIC_HELLO_FLAG) {
		MD5Update(&ctx, ibuf, EIGRP_MD5_BASIC_COMPUTE);
		MD5Update(&ctx, key->string, strlen(key->string));
		if (strlen(key->string) < 16)
			MD5Update(&ctx, zeropad, 16 - strlen(key->string));
	} else if (flags & EIGRP_AUTH_UPDATE_INIT_FLAG) {
		MD5Update(&ctx, ibuf, EIGRP_MD5_UPDATE_INIT_COMPUTE);
	} else if (flags & EIGRP_AUTH_UPDATE_FLAG) {
		MD5Update(&ctx, ibuf, EIGRP_MD5_BASIC_COMPUTE);
		MD5Update(&ctx, key->string, strlen(key->string));
		if (strlen(key->string) < 16)
			MD5Update(&ctx, zeropad, 16 - strlen(key->string));
		if (backup_end > (EIGRP_HEADER_LEN + EIGRP_AUTH_MD5_TLV_SIZE)) {
			MD5Update(&ctx,
				  ibuf + (EIGRP_HEADER_LEN
					  + EIGRP_AUTH_MD5_TLV_SIZE),
				  backup_end - 20
					  - (EIGRP_HEADER_LEN
					     + EIGRP_AUTH_MD5_TLV_SIZE));
		}
	}

	MD5Final(digest, &ctx);

	/* compare the two */
	if (memcmp(orig, digest, EIGRP_AUTH_TYPE_MD5_LEN) != 0) {
		zlog_warn("interface %s: eigrp_check_md5 checksum mismatch",
			  IF_NAME(nbr->ei));
		return 0;
	}

	/* save neighbor's crypt_seqnum */
	nbr->crypt_seqnum = authTLV->key_sequence;

	return 1;
}

int eigrp_make_sha256_digest(struct eigrp_interface *ei, struct stream *s,
			     uint8_t flags)
{
	struct key *key = NULL;
	struct keychain *keychain;
	char source_ip[PREFIX_STRLEN];

	unsigned char digest[EIGRP_AUTH_TYPE_SHA256_LEN];
	unsigned char buffer[1 + PLAINTEXT_LENGTH + 45 + 1] = {0};

	HMAC_SHA256_CTX ctx;
	void *ibuf;
	size_t backup_get, backup_end;
	struct TLV_SHA256_Authentication_Type *auth_TLV;

	ibuf = s->data;
	backup_end = s->endp;
	backup_get = s->getp;

	auth_TLV = eigrp_authTLV_SHA256_new();

	stream_set_getp(s, EIGRP_HEADER_LEN);
	stream_get(auth_TLV, s, EIGRP_AUTH_SHA256_TLV_SIZE);
	stream_set_getp(s, backup_get);

	keychain = keychain_lookup(ei->params.auth_keychain);
	if (keychain)
		key = key_lookup_for_send(keychain);

	if (!key) {
		zlog_warn(
			"Interface %s: Expected key value not found in config",
			ei->ifp->name);
		eigrp_authTLV_SHA256_free(auth_TLV);
		return 0;
	}

	inet_ntop(AF_INET, &ei->address.u.prefix4, source_ip, PREFIX_STRLEN);

	memset(&ctx, 0, sizeof(ctx));
	buffer[0] = '\n';
	memcpy(buffer + 1, key, strlen(key->string));
	memcpy(buffer + 1 + strlen(key->string), source_ip, strlen(source_ip));
	HMAC__SHA256_Init(&ctx, buffer,
			  1 + strlen(key->string) + strlen(source_ip));
	HMAC__SHA256_Update(&ctx, ibuf, strlen(ibuf));
	HMAC__SHA256_Final(digest, &ctx);


	/* Put hmac-sha256 digest to it's place */
	memcpy(auth_TLV->digest, digest, EIGRP_AUTH_TYPE_SHA256_LEN);

	stream_set_endp(s, EIGRP_HEADER_LEN);
	stream_put(s, auth_TLV, EIGRP_AUTH_SHA256_TLV_SIZE);
	stream_set_endp(s, backup_end);

	eigrp_authTLV_SHA256_free(auth_TLV);

	return EIGRP_AUTH_TYPE_SHA256_LEN;
}

int eigrp_check_sha256_digest(struct stream *s,
			      struct TLV_SHA256_Authentication_Type *authTLV,
			      struct eigrp_neighbor *nbr, uint8_t flags)
{
	return 1;
}

void eigrp_write(struct event *thread)
{
	struct eigrp *eigrp = EVENT_ARG(thread);
	struct eigrp_header *eigrph;
	struct eigrp_interface *ei;
	struct eigrp_packet *ep;
	struct sockaddr_in sa_dst;
	struct ip iph;
	struct msghdr msg;
	struct iovec iov[2];
	uint32_t seqno, ack;

	int ret;
	int flags = 0;
	struct listnode *node;
#ifdef WANT_EIGRP_WRITE_FRAGMENT
	static uint16_t ipid = 0;
#endif /* WANT_EIGRP_WRITE_FRAGMENT */
#define EIGRP_WRITE_IPHL_SHIFT 2

	node = listhead(eigrp->oi_write_q);
	assert(node);
	ei = listgetdata(node);
	assert(ei);

#ifdef WANT_EIGRP_WRITE_FRAGMENT
	/* seed ipid static with low order bits of time */
	if (ipid == 0)
		ipid = (time(NULL) & 0xffff);
#endif /* WANT_EIGRP_WRITE_FRAGMENT */

	/* Get one packet from queue. */
	ep = eigrp_fifo_next(ei->obuf);
	if (!ep) {
		flog_err(EC_LIB_DEVELOPMENT,
			 "%s: Interface %s no packet on queue?", __func__,
			 ei->ifp->name);
		goto out;
	}
	if (ep->length < EIGRP_HEADER_LEN) {
		flog_err(EC_EIGRP_PACKET, "%s: Packet just has a header?",
			 __func__);
		eigrp_header_dump((struct eigrp_header *)ep->s->data);
		eigrp_packet_delete(ei);
		goto out;
	}

	if (ep->dst.s_addr == htonl(EIGRP_MULTICAST_ADDRESS))
		eigrp_if_ipmulticast(eigrp, &ei->address, ei->ifp->ifindex);

	memset(&iph, 0, sizeof(iph));
	memset(&sa_dst, 0, sizeof(sa_dst));

	/*
	 * We build and schedule packets to go out
	 * in the future.  In the mean time we may
	 * process some update packets from the
	 * neighbor, thus making it necessary
	 * to update the ack we are using for
	 * this outgoing packet.
	 */
	eigrph = (struct eigrp_header *)STREAM_DATA(ep->s);
	seqno = ntohl(eigrph->sequence);
	ack = ntohl(eigrph->ack);
	if (ep->nbr && (ack != ep->nbr->recv_sequence_number)) {
		eigrph->ack = htonl(ep->nbr->recv_sequence_number);
		ack = ep->nbr->recv_sequence_number;
		eigrph->checksum = 0;
		eigrp_packet_checksum(ei, ep->s, ep->length);
	}

	sa_dst.sin_family = AF_INET;
#ifdef HAVE_STRUCT_SOCKADDR_IN_SIN_LEN
	sa_dst.sin_len = sizeof(sa_dst);
#endif /* HAVE_STRUCT_SOCKADDR_IN_SIN_LEN */
	sa_dst.sin_addr = ep->dst;
	sa_dst.sin_port = htons(0);

	/* Set DONTROUTE flag if dst is unicast. */
	if (!IN_MULTICAST(htonl(ep->dst.s_addr)))
		flags = MSG_DONTROUTE;

	iph.ip_hl = sizeof(struct ip) >> EIGRP_WRITE_IPHL_SHIFT;
	/* it'd be very strange for header to not be 4byte-word aligned but.. */
	if (sizeof(struct ip)
	    > (unsigned int)(iph.ip_hl << EIGRP_WRITE_IPHL_SHIFT))
		iph.ip_hl++; /* we presume sizeof struct ip cant overflow
				ip_hl.. */

	iph.ip_v = IPVERSION;
	iph.ip_tos = IPTOS_PREC_INTERNETCONTROL;
	iph.ip_len = (iph.ip_hl << EIGRP_WRITE_IPHL_SHIFT) + ep->length;

#if defined(__DragonFly__)
	/*
	 * DragonFly's raw socket expects ip_len/ip_off in network byte order.
	 */
	iph.ip_len = htons(iph.ip_len);
#endif

	iph.ip_off = 0;
	iph.ip_ttl = EIGRP_IP_TTL;
	iph.ip_p = IPPROTO_EIGRPIGP;
	iph.ip_sum = 0;
	iph.ip_src.s_addr = ei->address.u.prefix4.s_addr;
	iph.ip_dst.s_addr = ep->dst.s_addr;

	memset(&msg, 0, sizeof(msg));
	msg.msg_name = (caddr_t)&sa_dst;
	msg.msg_namelen = sizeof(sa_dst);
	msg.msg_iov = iov;
	msg.msg_iovlen = 2;

	iov[0].iov_base = (char *)&iph;
	iov[0].iov_len = iph.ip_hl << EIGRP_WRITE_IPHL_SHIFT;
	iov[1].iov_base = stream_pnt(ep->s);
	iov[1].iov_len = ep->length;

	/* send final fragment (could be first) */
	sockopt_iphdrincl_swab_htosys(&iph);
	ret = sendmsg(eigrp->fd, &msg, flags);
	sockopt_iphdrincl_swab_systoh(&iph);

	if (IS_DEBUG_EIGRP_TRANSMIT(0, SEND)) {
		eigrph = (struct eigrp_header *)STREAM_DATA(ep->s);
		zlog_debug(
			"Sending [%s][%d/%d] to [%pI4] via [%s] ret [%d].",
			lookup_msg(eigrp_packet_type_str, eigrph->opcode, NULL),
			seqno, ack, &ep->dst, IF_NAME(ei), ret);
	}

	if (ret < 0)
		zlog_warn(
			"*** sendmsg in eigrp_write failed to %pI4, id %d, off %d, len %d, interface %s, mtu %u: %s",
			&iph.ip_dst, iph.ip_id, iph.ip_off, iph.ip_len,
			ei->ifp->name, ei->ifp->mtu, safe_strerror(errno));

	/* Now delete packet from queue. */
	eigrp_packet_delete(ei);

out:
	if (eigrp_fifo_next(ei->obuf) == NULL) {
		ei->on_write_q = 0;
		list_delete_node(eigrp->oi_write_q, node);
	}

	/* If packets still remain in queue, call write thread. */
	if (!list_isempty(eigrp->oi_write_q)) {
		event_add_write(master, eigrp_write, eigrp, eigrp->fd,
				&eigrp->t_write);
	}
}

/* Starting point of packet process function. */
void eigrp_read(struct event *thread)
{
	int ret;
	struct stream *ibuf;
	struct eigrp *eigrp;
	struct eigrp_interface *ei;
	struct ip *iph;
	struct eigrp_header *eigrph;
	struct interface *ifp;
	struct eigrp_neighbor *nbr;
	struct in_addr srcaddr;
	uint16_t opcode = 0;
	uint16_t length = 0;

	/* first of all get interface pointer. */
	eigrp = EVENT_ARG(thread);

	/* prepare for next packet. */
	event_add_read(master, eigrp_read, eigrp, eigrp->fd, &eigrp->t_read);

	stream_reset(eigrp->ibuf);
	if (!(ibuf = eigrp_recv_packet(eigrp, eigrp->fd, &ifp, eigrp->ibuf))) {
		/* This raw packet is known to be at least as big as its IP
		 * header. */
		return;
	}

	/* Note that there should not be alignment problems with this assignment
	   because this is at the beginning of the stream data buffer. */
	iph = (struct ip *)STREAM_DATA(ibuf);

	// Substract IPv4 header size from EIGRP Packet itself
	if (iph->ip_v == 4)
		length = (iph->ip_len) - 20U;

	srcaddr = iph->ip_src;

	/* IP Header dump. */
	if (IS_DEBUG_EIGRP_TRANSMIT(0, RECV)
	    && IS_DEBUG_EIGRP_TRANSMIT(0, PACKET_DETAIL))
		eigrp_ip_header_dump(iph);

	/* Note that sockopt_iphdrincl_swab_systoh was called in
	 * eigrp_recv_packet. */
	if (ifp == NULL) {
		struct connected *c;
		/* Handle cases where the platform does not support retrieving
		   the ifindex,
		   and also platforms (such as Solaris 8) that claim to support
		   ifindex
		   retrieval but do not. */
		c = if_lookup_address((void *)&srcaddr, AF_INET,
				      eigrp->vrf_id);

		if (c == NULL)
			return;

		ifp = c->ifp;
	}

	/* associate packet with eigrp interface */
	ei = ifp->info;

	/* eigrp_verify_header() relies on a valid "ei" and thus can be called
	   only
	   after the checks below are passed. These checks in turn access the
	   fields of unverified "eigrph" structure for their own purposes and
	   must remain very accurate in doing this.
	*/
	if (!ei)
		return;

	/* Self-originated packet should be discarded silently. */
	if (eigrp_if_lookup_by_local_addr(eigrp, NULL, iph->ip_src)
	    || (IPV4_ADDR_SAME(&srcaddr, &ei->address.u.prefix4))) {
		if (IS_DEBUG_EIGRP_TRANSMIT(0, RECV))
			zlog_debug(
				"eigrp_read[%pI4]: Dropping self-originated packet",
				&srcaddr);
		return;
	}

	/* Advance from IP header to EIGRP header (iph->ip_hl has been verified
	   by eigrp_recv_packet() to be correct). */

	stream_forward_getp(ibuf, (iph->ip_hl * 4));
	eigrph = (struct eigrp_header *)stream_pnt(ibuf);

	if (IS_DEBUG_EIGRP_TRANSMIT(0, RECV)
	    && IS_DEBUG_EIGRP_TRANSMIT(0, PACKET_DETAIL))
		eigrp_header_dump(eigrph);

	if (ntohs(eigrph->ASNumber) != eigrp->AS) {
		if (IS_DEBUG_EIGRP_TRANSMIT(0, RECV))
			zlog_debug(
				"ignoring packet from router %u sent to %pI4, wrong AS Number received: %u",
				ntohs(eigrph->vrid), &iph->ip_dst,
				ntohs(eigrph->ASNumber));
		return;
	}

	/* If incoming interface is passive one, ignore it. */
	if (eigrp_if_is_passive(ei)) {
		if (IS_DEBUG_EIGRP_TRANSMIT(0, RECV))
			zlog_debug(
				"ignoring packet from router %u sent to %pI4, received on a passive interface, %pI4",
				ntohs(eigrph->vrid), &iph->ip_dst,
				&ei->address.u.prefix4);

		if (iph->ip_dst.s_addr == htonl(EIGRP_MULTICAST_ADDRESS)) {
			eigrp_if_set_multicast(ei);
		}
		return;
	}

	/* else it must be a local eigrp interface, check it was received on
	 * correct link
	 */
	else if (ei->ifp != ifp) {
		if (IS_DEBUG_EIGRP_TRANSMIT(0, RECV))
			zlog_warn(
				"Packet from [%pI4] received on wrong link %s",
				&iph->ip_src, ifp->name);
		return;
	}

	/* Verify more EIGRP header fields. */
	ret = eigrp_verify_header(ibuf, ei, iph, eigrph);
	if (ret < 0) {
		if (IS_DEBUG_EIGRP_TRANSMIT(0, RECV))
			zlog_debug(
				"eigrp_read[%pI4]: Header check failed, dropping.",
				&iph->ip_src);
		return;
	}

	/* calcualte the eigrp packet length, and move the pounter to the
	   start of the eigrp TLVs */
	opcode = eigrph->opcode;

	if (IS_DEBUG_EIGRP_TRANSMIT(0, RECV))
		zlog_debug(
			"Received [%s][%d/%d] length [%u] via [%s] src [%pI4] dst [%pI4]",
			lookup_msg(eigrp_packet_type_str, opcode, NULL),
			ntohl(eigrph->sequence), ntohl(eigrph->ack), length,
			IF_NAME(ei), &iph->ip_src, &iph->ip_dst);

	/* Read rest of the packet and call each sort of packet routine. */
	stream_forward_getp(ibuf, EIGRP_HEADER_LEN);

	/* New testing block of code for handling Acks */
	if (ntohl(eigrph->ack) != 0) {
		struct eigrp_packet *ep = NULL;

		nbr = eigrp_nbr_get(ei, eigrph, iph);

		// neighbor must be valid, eigrp_nbr_get creates if none existed
		assert(nbr);

		ep = eigrp_fifo_next(nbr->retrans_queue);
		if ((ep) && (ntohl(eigrph->ack) == ep->sequence_number)) {
			ep = eigrp_fifo_pop(nbr->retrans_queue);
			eigrp_packet_free(ep);

			if ((nbr->state == EIGRP_NEIGHBOR_PENDING)
			    && (ntohl(eigrph->ack)
				== nbr->init_sequence_number)) {
				eigrp_nbr_state_set(nbr, EIGRP_NEIGHBOR_UP);
				zlog_info(
					"Neighbor(%pI4) adjacency became full",
					&nbr->src);
				nbr->init_sequence_number = 0;
				nbr->recv_sequence_number =
					ntohl(eigrph->sequence);
				eigrp_update_send_EOT(nbr);
			} else
				eigrp_send_packet_reliably(nbr);
		}
		ep = eigrp_fifo_next(nbr->multicast_queue);
		if (ep) {
			if (ntohl(eigrph->ack) == ep->sequence_number) {
				ep = eigrp_fifo_pop(nbr->multicast_queue);
				eigrp_packet_free(ep);
				if (nbr->multicast_queue->count > 0) {
					eigrp_send_packet_reliably(nbr);
				}
			}
		}
	}


	switch (opcode) {
	case EIGRP_OPC_HELLO:
		eigrp_hello_receive(eigrp, iph, eigrph, ibuf, ei, length);
		break;
	case EIGRP_OPC_PROBE:
		//      eigrp_probe_receive(eigrp, iph, eigrph, ibuf, ei,
		//      length);
		break;
	case EIGRP_OPC_QUERY:
		eigrp_query_receive(eigrp, iph, eigrph, ibuf, ei, length);
		break;
	case EIGRP_OPC_REPLY:
		eigrp_reply_receive(eigrp, iph, eigrph, ibuf, ei, length);
		break;
	case EIGRP_OPC_REQUEST:
		//      eigrp_request_receive(eigrp, iph, eigrph, ibuf, ei,
		//      length);
		break;
	case EIGRP_OPC_SIAQUERY:
		eigrp_query_receive(eigrp, iph, eigrph, ibuf, ei, length);
		break;
	case EIGRP_OPC_SIAREPLY:
		eigrp_reply_receive(eigrp, iph, eigrph, ibuf, ei, length);
		break;
	case EIGRP_OPC_UPDATE:
		eigrp_update_receive(eigrp, iph, eigrph, ibuf, ei, length);
		break;
	default:
		zlog_warn(
			"interface %s: EIGRP packet header type %d unsupported",
			IF_NAME(ei), opcode);
		break;
	}
}

static struct stream *eigrp_recv_packet(struct eigrp *eigrp,
					int fd, struct interface **ifp,
					struct stream *ibuf)
{
	int ret;
	struct ip *iph;
	uint16_t ip_len;
	unsigned int ifindex = 0;
	struct iovec iov;
	/* Header and data both require alignment. */
	char buff[CMSG_SPACE(SOPT_SIZE_CMSG_IFINDEX_IPV4())];
	struct msghdr msgh;

	memset(&msgh, 0, sizeof(msgh));
	msgh.msg_iov = &iov;
	msgh.msg_iovlen = 1;
	msgh.msg_control = (caddr_t)buff;
	msgh.msg_controllen = sizeof(buff);

	ret = stream_recvmsg(ibuf, fd, &msgh, 0, (EIGRP_PACKET_MAX_LEN + 1));
	if (ret < 0) {
		zlog_warn("stream_recvmsg failed: %s", safe_strerror(errno));
		return NULL;
	}
	if ((unsigned int)ret < sizeof(*iph)) /* ret must be > 0 now */
	{
		zlog_warn(
			"%s: discarding runt packet of length %d (ip header size is %u)",
			__func__, ret, (unsigned int)sizeof(*iph));
		return NULL;
	}

	/* Note that there should not be alignment problems with this assignment
	   because this is at the beginning of the stream data buffer. */
	iph = (struct ip *)STREAM_DATA(ibuf);
	sockopt_iphdrincl_swab_systoh(iph);

	ip_len = iph->ip_len;

#if defined(__FreeBSD__) && (__FreeBSD_version < 1000000)
	/*
	 * Kernel network code touches incoming IP header parameters,
	 * before protocol specific processing.
	 *
	 *   1) Convert byteorder to host representation.
	 *      --> ip_len, ip_id, ip_off
	 *
	 *   2) Adjust ip_len to strip IP header size!
	 *      --> If user process receives entire IP packet via RAW
	 *          socket, it must consider adding IP header size to
	 *          the "ip_len" field of "ip" structure.
	 *
	 * For more details, see <netinet/ip_input.c>.
	 */
	ip_len = ip_len + (iph->ip_hl << 2);
#endif

#if defined(__DragonFly__)
	/*
	 * in DragonFly's raw socket, ip_len/ip_off are read
	 * in network byte order.
	 * As OpenBSD < 200311 adjust ip_len to strip IP header size!
	 */
	ip_len = ntohs(iph->ip_len) + (iph->ip_hl << 2);
#endif

	ifindex = getsockopt_ifindex(AF_INET, &msgh);

	*ifp = if_lookup_by_index(ifindex, eigrp->vrf_id);

	if (ret != ip_len) {
		zlog_warn(
			"%s read length mismatch: ip_len is %d, but recvmsg returned %d",
			__func__, ip_len, ret);
		return NULL;
	}

	return ibuf;
}

struct eigrp_fifo *eigrp_fifo_new(void)
{
	struct eigrp_fifo *new;

	new = XCALLOC(MTYPE_EIGRP_FIFO, sizeof(struct eigrp_fifo));
	return new;
}

/* Free eigrp packet fifo. */
void eigrp_fifo_free(struct eigrp_fifo *fifo)
{
	struct eigrp_packet *ep;
	struct eigrp_packet *next;

	for (ep = fifo->head; ep; ep = next) {
		next = ep->next;
		eigrp_packet_free(ep);
	}
	fifo->head = fifo->tail = NULL;
	fifo->count = 0;

	XFREE(MTYPE_EIGRP_FIFO, fifo);
}

/* Free eigrp fifo entries without destroying fifo itself*/
void eigrp_fifo_reset(struct eigrp_fifo *fifo)
{
	struct eigrp_packet *ep;
	struct eigrp_packet *next;

	for (ep = fifo->head; ep; ep = next) {
		next = ep->next;
		eigrp_packet_free(ep);
	}
	fifo->head = fifo->tail = NULL;
	fifo->count = 0;
}

struct eigrp_packet *eigrp_packet_new(size_t size, struct eigrp_neighbor *nbr)
{
	struct eigrp_packet *new;

	new = XCALLOC(MTYPE_EIGRP_PACKET, sizeof(struct eigrp_packet));
	new->s = stream_new(size);
	new->retrans_counter = 0;
	new->nbr = nbr;

	return new;
}

void eigrp_send_packet_reliably(struct eigrp_neighbor *nbr)
{
	struct eigrp_packet *ep;

	ep = eigrp_fifo_next(nbr->retrans_queue);

	if (ep) {
		struct eigrp_packet *duplicate;
		duplicate = eigrp_packet_duplicate(ep, nbr);
		/* Add packet to the top of the interface output queue*/
		eigrp_fifo_push(nbr->ei->obuf, duplicate);

		/*Start retransmission timer*/
		event_add_timer(master, eigrp_unack_packet_retrans, nbr,
				EIGRP_PACKET_RETRANS_TIME,
				&ep->t_retrans_timer);

		/*Increment sequence number counter*/
		nbr->ei->eigrp->sequence_number++;

		/* Hook thread to write packet. */
		if (nbr->ei->on_write_q == 0) {
			listnode_add(nbr->ei->eigrp->oi_write_q, nbr->ei);
			nbr->ei->on_write_q = 1;
		}
		event_add_write(master, eigrp_write, nbr->ei->eigrp,
				nbr->ei->eigrp->fd, &nbr->ei->eigrp->t_write);
	}
}

/* Calculate EIGRP checksum */
void eigrp_packet_checksum(struct eigrp_interface *ei, struct stream *s,
			   uint16_t length)
{
	struct eigrp_header *eigrph;

	eigrph = (struct eigrp_header *)STREAM_DATA(s);

	/* Calculate checksum. */
	eigrph->checksum = in_cksum(eigrph, length);
}

/* Make EIGRP header. */
void eigrp_packet_header_init(int type, struct eigrp *eigrp, struct stream *s,
			      uint32_t flags, uint32_t sequence, uint32_t ack)
{
	struct eigrp_header *eigrph;

	stream_reset(s);
	eigrph = (struct eigrp_header *)STREAM_DATA(s);

	eigrph->version = (uint8_t)EIGRP_HEADER_VERSION;
	eigrph->opcode = (uint8_t)type;
	eigrph->checksum = 0;

	eigrph->vrid = htons(eigrp->vrid);
	eigrph->ASNumber = htons(eigrp->AS);
	eigrph->ack = htonl(ack);
	eigrph->sequence = htonl(sequence);
	//  if(flags == EIGRP_INIT_FLAG)
	//    eigrph->sequence = htonl(3);
	eigrph->flags = htonl(flags);

	if (IS_DEBUG_EIGRP_TRANSMIT(0, PACKET_DETAIL))
		zlog_debug("Packet Header Init Seq [%u] Ack [%u]",
			   htonl(eigrph->sequence), htonl(eigrph->ack));

	stream_forward_endp(s, EIGRP_HEADER_LEN);
}

/* Add new packet to head of fifo. */
void eigrp_fifo_push(struct eigrp_fifo *fifo, struct eigrp_packet *ep)
{
	ep->next = fifo->head;
	ep->previous = NULL;

	if (fifo->tail == NULL)
		fifo->tail = ep;

	if (fifo->count != 0)
		fifo->head->previous = ep;

	fifo->head = ep;

	fifo->count++;
}

/* Return last fifo entry. */
struct eigrp_packet *eigrp_fifo_next(struct eigrp_fifo *fifo)
{
	return fifo->tail;
}

void eigrp_packet_delete(struct eigrp_interface *ei)
{
	struct eigrp_packet *ep;

	ep = eigrp_fifo_pop(ei->obuf);

	if (ep)
		eigrp_packet_free(ep);
}

void eigrp_packet_free(struct eigrp_packet *ep)
{
	if (ep->s)
		stream_free(ep->s);

	EVENT_OFF(ep->t_retrans_timer);

	XFREE(MTYPE_EIGRP_PACKET, ep);
}

/* EIGRP Header verification. */
static int eigrp_verify_header(struct stream *ibuf, struct eigrp_interface *ei,
			       struct ip *iph, struct eigrp_header *eigrph)
{
	/* Check network mask, Silently discarded. */
	if (!eigrp_check_network_mask(ei, iph->ip_src)) {
		zlog_warn(
			"interface %s: eigrp_read network address is not same [%pI4]",
			IF_NAME(ei), &iph->ip_src);
		return -1;
	}
	//
	//  /* Check authentication. The function handles logging actions, where
	//  required. */
	//  if (! eigrp_check_auth(ei, eigrph))
	//    return -1;

	return 0;
}

/* Unbound socket will accept any Raw IP packets if proto is matched.
   To prevent it, compare src IP address and i/f address with masking
   i/f network mask. */
static int eigrp_check_network_mask(struct eigrp_interface *ei,
				    struct in_addr ip_src)
{
	struct in_addr mask, me, him;

	if (ei->type == EIGRP_IFTYPE_POINTOPOINT)
		return 1;

	masklen2ip(ei->address.prefixlen, &mask);

	me.s_addr = ei->address.u.prefix4.s_addr & mask.s_addr;
	him.s_addr = ip_src.s_addr & mask.s_addr;

	if (IPV4_ADDR_SAME(&me, &him))
		return 1;

	return 0;
}

void eigrp_unack_packet_retrans(struct event *thread)
{
	struct eigrp_neighbor *nbr;
	nbr = (struct eigrp_neighbor *)EVENT_ARG(thread);

	struct eigrp_packet *ep;
	ep = eigrp_fifo_next(nbr->retrans_queue);

	if (ep) {
		struct eigrp_packet *duplicate;
		duplicate = eigrp_packet_duplicate(ep, nbr);

		/* Add packet to the top of the interface output queue*/
		eigrp_fifo_push(nbr->ei->obuf, duplicate);

		ep->retrans_counter++;
		if (ep->retrans_counter == EIGRP_PACKET_RETRANS_MAX) {
			eigrp_retrans_count_exceeded(ep, nbr);
			return;
		}

		/*Start retransmission timer*/
		event_add_timer(master, eigrp_unack_packet_retrans, nbr,
				EIGRP_PACKET_RETRANS_TIME,
				&ep->t_retrans_timer);

		/* Hook thread to write packet. */
		if (nbr->ei->on_write_q == 0) {
			listnode_add(nbr->ei->eigrp->oi_write_q, nbr->ei);
			nbr->ei->on_write_q = 1;
		}
		event_add_write(master, eigrp_write, nbr->ei->eigrp,
				nbr->ei->eigrp->fd, &nbr->ei->eigrp->t_write);
	}
}

void eigrp_unack_multicast_packet_retrans(struct event *thread)
{
	struct eigrp_neighbor *nbr;
	nbr = (struct eigrp_neighbor *)EVENT_ARG(thread);

	struct eigrp_packet *ep;
	ep = eigrp_fifo_next(nbr->multicast_queue);

	if (ep) {
		struct eigrp_packet *duplicate;
		duplicate = eigrp_packet_duplicate(ep, nbr);
		/* Add packet to the top of the interface output queue*/
		eigrp_fifo_push(nbr->ei->obuf, duplicate);

		ep->retrans_counter++;
		if (ep->retrans_counter == EIGRP_PACKET_RETRANS_MAX) {
			eigrp_retrans_count_exceeded(ep, nbr);
			return;
		}

		/*Start retransmission timer*/
		event_add_timer(master, eigrp_unack_multicast_packet_retrans,
				nbr, EIGRP_PACKET_RETRANS_TIME,
				&ep->t_retrans_timer);

		/* Hook thread to write packet. */
		if (nbr->ei->on_write_q == 0) {
			listnode_add(nbr->ei->eigrp->oi_write_q, nbr->ei);
			nbr->ei->on_write_q = 1;
		}
		event_add_write(master, eigrp_write, nbr->ei->eigrp,
				nbr->ei->eigrp->fd, &nbr->ei->eigrp->t_write);
	}
}

/* Get packet from tail of fifo. */
struct eigrp_packet *eigrp_fifo_pop(struct eigrp_fifo *fifo)
{
	struct eigrp_packet *ep = NULL;

	ep = fifo->tail;

	if (ep) {
		fifo->tail = ep->previous;

		if (fifo->tail == NULL)
			fifo->head = NULL;
		else
			fifo->tail->next = NULL;

		fifo->count--;
	}

	return ep;
}

struct eigrp_packet *eigrp_packet_duplicate(struct eigrp_packet *old,
					    struct eigrp_neighbor *nbr)
{
	struct eigrp_packet *new;

	new = eigrp_packet_new(EIGRP_PACKET_MTU(nbr->ei->ifp->mtu), nbr);
	new->length = old->length;
	new->retrans_counter = old->retrans_counter;
	new->dst = old->dst;
	new->sequence_number = old->sequence_number;
	stream_copy(new->s, old->s);

	return new;
}

static struct TLV_IPv4_Internal_type *eigrp_IPv4_InternalTLV_new(void)
{
	struct TLV_IPv4_Internal_type *new;

	new = XCALLOC(MTYPE_EIGRP_IPV4_INT_TLV,
		      sizeof(struct TLV_IPv4_Internal_type));

	return new;
}

struct TLV_IPv4_Internal_type *eigrp_read_ipv4_tlv(struct stream *s)
{
	struct TLV_IPv4_Internal_type *tlv;
	uint32_t destination_tmp;

	tlv = eigrp_IPv4_InternalTLV_new();

	tlv->type = stream_getw(s);
	tlv->length = stream_getw(s);
	tlv->forward.s_addr = stream_getl(s);
	tlv->metric.delay = stream_getl(s);
	tlv->metric.bandwidth = stream_getl(s);
	tlv->metric.mtu[0] = stream_getc(s);
	tlv->metric.mtu[1] = stream_getc(s);
	tlv->metric.mtu[2] = stream_getc(s);
	tlv->metric.hop_count = stream_getc(s);
	tlv->metric.reliability = stream_getc(s);
	tlv->metric.load = stream_getc(s);
	tlv->metric.tag = stream_getc(s);
	tlv->metric.flags = stream_getc(s);

	tlv->prefix_length = stream_getc(s);

	destination_tmp = stream_getc(s) << 24;
	if (tlv->prefix_length > 8)
		destination_tmp |= stream_getc(s) << 16;
	if (tlv->prefix_length > 16)
		destination_tmp |= stream_getc(s) << 8;
	if (tlv->prefix_length > 24)
		destination_tmp |= stream_getc(s);

	tlv->destination.s_addr = htonl(destination_tmp);

	return tlv;
}

uint16_t eigrp_add_internalTLV_to_stream(struct stream *s,
					 struct eigrp_prefix_descriptor *pe)
{
	uint16_t length;

	stream_putw(s, EIGRP_TLV_IPv4_INT);
	switch (pe->destination->prefixlen) {
	case 0:
	case 1:
	case 2:
	case 3:
	case 4:
	case 5:
	case 6:
	case 7:
	case 8:
		length = EIGRP_TLV_IPV4_SIZE_GRT_0_BIT;
		stream_putw(s, length);
		break;
	case 9:
	case 10:
	case 11:
	case 12:
	case 13:
	case 14:
	case 15:
	case 16:
		length = EIGRP_TLV_IPV4_SIZE_GRT_8_BIT;
		stream_putw(s, length);
		break;
	case 17:
	case 18:
	case 19:
	case 20:
	case 21:
	case 22:
	case 23:
	case 24:
		length = EIGRP_TLV_IPV4_SIZE_GRT_16_BIT;
		stream_putw(s, length);
		break;
	case 25:
	case 26:
	case 27:
	case 28:
	case 29:
	case 30:
	case 31:
	case 32:
		length = EIGRP_TLV_IPV4_SIZE_GRT_24_BIT;
		stream_putw(s, length);
		break;
	default:
		flog_err(EC_LIB_DEVELOPMENT, "%s: Unexpected prefix length: %d",
			 __func__, pe->destination->prefixlen);
		return 0;
	}
	stream_putl(s, 0x00000000);

	/*Metric*/
	stream_putl(s, pe->reported_metric.delay);
	stream_putl(s, pe->reported_metric.bandwidth);
	stream_putc(s, pe->reported_metric.mtu[2]);
	stream_putc(s, pe->reported_metric.mtu[1]);
	stream_putc(s, pe->reported_metric.mtu[0]);
	stream_putc(s, pe->reported_metric.hop_count);
	stream_putc(s, pe->reported_metric.reliability);
	stream_putc(s, pe->reported_metric.load);
	stream_putc(s, pe->reported_metric.tag);
	stream_putc(s, pe->reported_metric.flags);

	stream_putc(s, pe->destination->prefixlen);

	stream_putc(s, (ntohl(pe->destination->u.prefix4.s_addr) >> 24) & 0xFF);
	if (pe->destination->prefixlen > 8)
		stream_putc(s, (ntohl(pe->destination->u.prefix4.s_addr) >> 16) & 0xFF);
	if (pe->destination->prefixlen > 16)
		stream_putc(s, (ntohl(pe->destination->u.prefix4.s_addr) >> 8) & 0xFF);
	if (pe->destination->prefixlen > 24)
		stream_putc(s, ntohl(pe->destination->u.prefix4.s_addr) & 0xFF);

	return length;
}

uint16_t eigrp_add_authTLV_MD5_to_stream(struct stream *s,
					 struct eigrp_interface *ei)
{
	struct key *key;
	struct keychain *keychain;
	struct TLV_MD5_Authentication_Type *authTLV;

	authTLV = eigrp_authTLV_MD5_new();

	authTLV->type = htons(EIGRP_TLV_AUTH);
	authTLV->length = htons(EIGRP_AUTH_MD5_TLV_SIZE);
	authTLV->auth_type = htons(EIGRP_AUTH_TYPE_MD5);
	authTLV->auth_length = htons(EIGRP_AUTH_TYPE_MD5_LEN);
	authTLV->key_sequence = 0;
	memset(authTLV->Nullpad, 0, sizeof(authTLV->Nullpad));

	keychain = keychain_lookup(ei->params.auth_keychain);
	if (keychain)
		key = key_lookup_for_send(keychain);
	else {
		free(ei->params.auth_keychain);
		ei->params.auth_keychain = NULL;
		eigrp_authTLV_MD5_free(authTLV);
		return 0;
	}

	if (key) {
		authTLV->key_id = htonl(key->index);
		memset(authTLV->digest, 0, EIGRP_AUTH_TYPE_MD5_LEN);
		stream_put(s, authTLV,
			   sizeof(struct TLV_MD5_Authentication_Type));
		eigrp_authTLV_MD5_free(authTLV);
		return EIGRP_AUTH_MD5_TLV_SIZE;
	}

	eigrp_authTLV_MD5_free(authTLV);

	return 0;
}

uint16_t eigrp_add_authTLV_SHA256_to_stream(struct stream *s,
					    struct eigrp_interface *ei)
{
	struct key *key;
	struct keychain *keychain;
	struct TLV_SHA256_Authentication_Type *authTLV;

	authTLV = eigrp_authTLV_SHA256_new();

	authTLV->type = htons(EIGRP_TLV_AUTH);
	authTLV->length = htons(EIGRP_AUTH_SHA256_TLV_SIZE);
	authTLV->auth_type = htons(EIGRP_AUTH_TYPE_SHA256);
	authTLV->auth_length = htons(EIGRP_AUTH_TYPE_SHA256_LEN);
	authTLV->key_sequence = 0;
	memset(authTLV->Nullpad, 0, sizeof(authTLV->Nullpad));

	keychain = keychain_lookup(ei->params.auth_keychain);
	if (keychain)
		key = key_lookup_for_send(keychain);
	else {
		free(ei->params.auth_keychain);
		ei->params.auth_keychain = NULL;
		eigrp_authTLV_SHA256_free(authTLV);
		return 0;
	}

	if (key) {
		authTLV->key_id = 0;
		memset(authTLV->digest, 0, EIGRP_AUTH_TYPE_SHA256_LEN);
		stream_put(s, authTLV,
			   sizeof(struct TLV_SHA256_Authentication_Type));
		eigrp_authTLV_SHA256_free(authTLV);
		return EIGRP_AUTH_SHA256_TLV_SIZE;
	}

	eigrp_authTLV_SHA256_free(authTLV);

	return 0;
}

struct TLV_MD5_Authentication_Type *eigrp_authTLV_MD5_new(void)
{
	struct TLV_MD5_Authentication_Type *new;

	new = XCALLOC(MTYPE_EIGRP_AUTH_TLV,
		      sizeof(struct TLV_MD5_Authentication_Type));

	return new;
}

void eigrp_authTLV_MD5_free(struct TLV_MD5_Authentication_Type *authTLV)
{
	XFREE(MTYPE_EIGRP_AUTH_TLV, authTLV);
}

struct TLV_SHA256_Authentication_Type *eigrp_authTLV_SHA256_new(void)
{
	struct TLV_SHA256_Authentication_Type *new;

	new = XCALLOC(MTYPE_EIGRP_AUTH_SHA256_TLV,
		      sizeof(struct TLV_SHA256_Authentication_Type));

	return new;
}

void eigrp_authTLV_SHA256_free(struct TLV_SHA256_Authentication_Type *authTLV)
{
	XFREE(MTYPE_EIGRP_AUTH_SHA256_TLV, authTLV);
}

void eigrp_IPv4_InternalTLV_free(
	struct TLV_IPv4_Internal_type *IPv4_InternalTLV)
{
	XFREE(MTYPE_EIGRP_IPV4_INT_TLV, IPv4_InternalTLV);
}

struct TLV_Sequence_Type *eigrp_SequenceTLV_new(void)
{
	struct TLV_Sequence_Type *new;

	new = XCALLOC(MTYPE_EIGRP_SEQ_TLV, sizeof(struct TLV_Sequence_Type));

	return new;
}