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/* $OpenBSD: arptab.c,v 1.22 2013/11/12 19:49:42 deraadt Exp $ */
/*
* Copyright (c) 1984, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Sun Microsystems, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* set arp table entries
*/
#include <sys/param.h>
#include <sys/file.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/if_ether.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <paths.h>
#include <syslog.h>
#include <string.h>
#include <err.h>
static pid_t pid;
static int s = -1;
static void
getsocket(void)
{
s = socket(PF_ROUTE, SOCK_RAW, 0);
if (s < 0)
err(1, "arp: socket");
}
struct sockaddr_in so_mask = {8, 0, 0, { 0xffffffff}};
struct sockaddr_inarp blank_sin = {sizeof(blank_sin), AF_INET }, sin_m;
struct sockaddr_dl blank_sdl = {sizeof(blank_sdl), AF_LINK }, sdl_m;
time_t expire_time;
int flags, export_only, doing_proxy;
struct {
struct rt_msghdr m_rtm;
char m_space[512];
} m_rtmsg;
int arptab_set(u_char *, u_int32_t);
int rtmsg(int);
/*
* Set an individual arp entry
*/
int
arptab_set(u_char *eaddr, u_int32_t host)
{
struct sockaddr_inarp *sin = &sin_m;
struct rt_msghdr *rtm = &(m_rtmsg.m_rtm);
struct sockaddr_dl *sdl;
struct timeval now;
int rt;
getsocket();
pid = getpid();
sdl_m = blank_sdl;
sin_m = blank_sin;
sin->sin_addr.s_addr = host;
memcpy((u_char *)LLADDR(&sdl_m), (char *)eaddr, 6);
sdl_m.sdl_alen = 6;
expire_time = 0;
doing_proxy = flags = export_only = 0;
gettimeofday(&now, 0);
expire_time = now.tv_sec + 20 * 60;
tryagain:
if (rtmsg(RTM_GET) < 0) {
syslog(LOG_ERR,"%s: %m", inet_ntoa(sin->sin_addr));
close(s);
s = -1;
return (1);
}
sin = (struct sockaddr_inarp *)((char *)rtm + rtm->rtm_hdrlen);
sdl = (struct sockaddr_dl *)(sin->sin_len + (char *)sin);
if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) {
if (sdl->sdl_family == AF_LINK &&
(rtm->rtm_flags & RTF_LLINFO) &&
!(rtm->rtm_flags & RTF_GATEWAY))
switch (sdl->sdl_type) {
case IFT_ETHER:
case IFT_FDDI:
case IFT_ISO88023:
case IFT_ISO88024:
case IFT_ISO88025:
goto overwrite;
default:
break;
}
if (doing_proxy == 0) {
syslog(LOG_ERR, "arptab_set: can only proxy for %s",
inet_ntoa(sin->sin_addr));
close(s);
s = -1;
return (1);
}
if (sin_m.sin_other & SIN_PROXY) {
syslog(LOG_ERR,
"arptab_set: proxy entry exists for non 802 device");
close(s);
s = -1;
return(1);
}
sin_m.sin_other = SIN_PROXY;
export_only = 1;
goto tryagain;
}
overwrite:
if (sdl->sdl_family != AF_LINK) {
syslog(LOG_ERR,
"arptab_set: cannot intuit interface index and type for %s",
inet_ntoa(sin->sin_addr));
close(s);
s = -1;
return (1);
}
sdl_m.sdl_type = sdl->sdl_type;
sdl_m.sdl_index = sdl->sdl_index;
rt = rtmsg(RTM_ADD);
close(s);
s = -1;
return (rt);
}
int
rtmsg(int cmd)
{
static int seq;
struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
char *cp = m_rtmsg.m_space;
int l;
errno = 0;
if (cmd == RTM_DELETE)
goto doit;
memset((char *)&m_rtmsg, 0, sizeof(m_rtmsg));
rtm->rtm_flags = flags;
rtm->rtm_version = RTM_VERSION;
switch (cmd) {
default:
syslog(LOG_ERR, "arptab_set: internal wrong cmd");
exit(1);
case RTM_ADD:
rtm->rtm_addrs |= RTA_GATEWAY;
rtm->rtm_rmx.rmx_expire = expire_time;
rtm->rtm_inits = RTV_EXPIRE;
rtm->rtm_flags |= (RTF_HOST | RTF_STATIC);
sin_m.sin_other = 0;
if (doing_proxy) {
if (export_only)
sin_m.sin_other = SIN_PROXY;
else {
rtm->rtm_addrs |= RTA_NETMASK;
rtm->rtm_flags &= ~RTF_HOST;
}
}
/* FALLTHROUGH */
case RTM_GET:
rtm->rtm_addrs |= RTA_DST;
}
#define NEXTADDR(w, s) \
if (rtm->rtm_addrs & (w)) { \
memcpy(cp, (char *)&s, sizeof(s)); \
cp += sizeof(s); \
}
NEXTADDR(RTA_DST, sin_m);
NEXTADDR(RTA_GATEWAY, sdl_m);
NEXTADDR(RTA_NETMASK, so_mask);
rtm->rtm_msglen = cp - (char *)&m_rtmsg;
doit:
l = rtm->rtm_msglen;
rtm->rtm_seq = ++seq;
rtm->rtm_type = cmd;
if (write(s, (char *)&m_rtmsg, l) < 0) {
if (errno != ESRCH && errno != EEXIST) {
syslog(LOG_ERR, "writing to routing socket: %m");
return (-1);
}
}
do {
l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
} while (l > 0 && (rtm->rtm_version != RTM_VERSION ||
rtm->rtm_seq != seq || rtm->rtm_pid != pid));
if (l < 0)
syslog(LOG_ERR, "arptab_set: read from routing socket: %m");
return (0);
}
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