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/* $OpenBSD: packet.c,v 1.13 2016/12/23 14:53:16 jca Exp $ */
/*
* Copyright (c) 2006 Michele Marchetto <mydecay@openbeer.it>
* Copyright (c) 2004, 2005 Esben Norby <norby@openbsd.org>
*
* Permission to use, copy, modify, and 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 <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/udp.h>
#include <arpa/inet.h>
#include <net/if_dl.h>
#include <errno.h>
#include <event.h>
#include <stdlib.h>
#include <string.h>
#include "ripd.h"
#include "rip.h"
#include "log.h"
#include "ripe.h"
int rip_hdr_sanity_check(struct rip_hdr *);
struct iface *find_iface(struct ripd_conf *, unsigned int, struct in_addr);
int
gen_rip_hdr(struct ibuf *buf, u_int8_t command)
{
struct rip_hdr rip_hdr;
bzero(&rip_hdr, sizeof(rip_hdr));
rip_hdr.version = RIP_VERSION;
rip_hdr.command = command;
return (ibuf_add(buf, &rip_hdr, sizeof(rip_hdr)));
}
/* send and receive packets */
int
send_packet(struct iface *iface, void *pkt, size_t len, struct sockaddr_in *dst)
{
/* set outgoing interface for multicast traffic */
if (IN_MULTICAST(ntohl(dst->sin_addr.s_addr)))
if (if_set_mcast(iface) == -1) {
log_warn("send_packet: error setting multicast "
"interface, %s", iface->name);
return (-1);
}
if (sendto(iface->fd, pkt, len, 0,
(struct sockaddr *)dst, sizeof(*dst)) == -1) {
log_warn("send_packet: error sending packet on interface %s",
iface->name);
return (-1);
}
return (0);
}
void
recv_packet(int fd, short event, void *bula)
{
union {
struct cmsghdr hdr;
char buf[CMSG_SPACE(sizeof(struct sockaddr_dl))];
} cmsgbuf;
struct sockaddr_in src;
struct iovec iov;
struct msghdr msg;
struct cmsghdr *cmsg;
struct sockaddr_dl *dst = NULL;
struct nbr_failed *nbr_failed = NULL;
struct ripd_conf *xconf = bula;
struct iface *iface;
struct rip_hdr *rip_hdr;
struct nbr *nbr;
u_int8_t *buf;
ssize_t r;
u_int16_t len, srcport;
u_int32_t auth_crypt_num = 0;
if (event != EV_READ)
return;
/* setup buffer */
buf = pkt_ptr;
bzero(&msg, sizeof(msg));
iov.iov_base = buf;
iov.iov_len = IBUF_READ_SIZE;
msg.msg_name = &src;
msg.msg_namelen = sizeof(src);
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = &cmsgbuf.buf;
msg.msg_controllen = sizeof(cmsgbuf.buf);
if ((r = recvmsg(fd, &msg, 0)) == -1) {
if (errno != EINTR && errno != EAGAIN)
log_debug("recv_packet: read error: %s",
strerror(errno));
return;
}
for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
cmsg = CMSG_NXTHDR(&msg, cmsg)) {
if (cmsg->cmsg_level == IPPROTO_IP &&
cmsg->cmsg_type == IP_RECVIF) {
dst = (struct sockaddr_dl *)CMSG_DATA(cmsg);
break;
}
}
if (dst == NULL)
return;
len = (u_int16_t)r;
/* Check the packet is not from one of the local interfaces */
LIST_FOREACH(iface, &xconf->iface_list, entry) {
if (iface->addr.s_addr == src.sin_addr.s_addr)
return;
}
/* find a matching interface */
if ((iface = find_iface(xconf, dst->sdl_index, src.sin_addr)) == NULL) {
log_debug("recv_packet: cannot find a matching interface");
return;
}
srcport = ntohs(src.sin_port);
/* RIP header sanity checks */
if (len < RIP_HDR_LEN) {
log_debug("recv_packet: bad packet size");
return;
}
rip_hdr = (struct rip_hdr *)buf;
if (rip_hdr_sanity_check(rip_hdr) == -1)
return;
nbr = nbr_find_ip(iface, src.sin_addr.s_addr);
if (nbr == NULL && iface->auth_type == AUTH_CRYPT)
nbr_failed = nbr_failed_find(iface, src.sin_addr.s_addr);
/* switch RIP command */
switch (rip_hdr->command) {
case COMMAND_REQUEST:
/* Requests don't create a real neighbor, just a temporary
* one to build the response.
*/
if ((msg.msg_flags & MSG_MCAST) == 0 && srcport == RIP_PORT)
return;
if (nbr == NULL) {
nbr = nbr_new(src.sin_addr.s_addr, iface);
nbr->addr = src.sin_addr;
}
nbr->port = srcport;
nbr_fsm(nbr, NBR_EVT_REQUEST_RCVD);
buf += RIP_HDR_LEN;
len -= RIP_HDR_LEN;
recv_request(iface, nbr, buf, len);
break;
case COMMAND_RESPONSE:
if (srcport != RIP_PORT)
return;
if (auth_validate(&buf, &len, iface, nbr, nbr_failed,
&auth_crypt_num)) {
log_warnx("recv_packet: authentication error, "
"interface %s", iface->name);
return;
}
if (nbr == NULL) {
nbr = nbr_new(src.sin_addr.s_addr, iface);
if (nbr_failed != NULL)
nbr_failed_delete(nbr_failed);
nbr->addr = src.sin_addr;
}
nbr->auth_seq_num = auth_crypt_num;
nbr_fsm(nbr, NBR_EVT_RESPONSE_RCVD);
recv_response(iface, nbr, buf, len);
break;
default:
log_debug("recv_packet: unknown RIP command, interface %s",
iface->name);
}
}
int
rip_hdr_sanity_check(struct rip_hdr *rip_hdr)
{
if (rip_hdr->version != RIP_VERSION) {
log_debug("rip_hdr_sanity_check: invalid RIP version %d",
rip_hdr->version);
return (-1);
}
return (0);
}
struct iface *
find_iface(struct ripd_conf *xconf, unsigned int ifindex, struct in_addr src)
{
struct iface *iface = NULL;
/* returned interface needs to be active */
LIST_FOREACH(iface, &xconf->iface_list, entry) {
if (ifindex == 0 || ifindex != iface->ifindex)
continue;
if (iface->passive)
continue;
if ((iface->addr.s_addr & iface->mask.s_addr) ==
(src.s_addr & iface->mask.s_addr))
return (iface);
if (iface->dst.s_addr && iface->dst.s_addr == src.s_addr)
return (iface);
}
return (NULL);
}
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