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/*
* Copyright (c) 2000
* The Regents of the University of California. All rights reserved.
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the Computer Systems
* Engineering Group at Lawrence Berkeley Laboratory.
* 4. Neither the name of the University nor of the Laboratory 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.
*/
#ifndef lint
static const char rcsid[] =
"@(#) $Id: findsaddr-linux.c,v 1.1 2000/11/23 20:17:12 leres Exp $ (LBL)";
#endif
/* XXX linux is different (as usual) */
#include <netinet/in.h>
#include <sys/socket.h>
#include <errno.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
typedef uint32_t __u32;
typedef uint16_t __u16;
typedef uint8_t __u8;
typedef int32_t __s32;
#include <linux/rtnetlink.h>
#include "gnuc.h"
#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif
#include "findsaddr.h"
#include "ifaddrlist.h"
#include "traceroute.h"
/*
* Return the source address for the given destination address
*/
const char *
findsaddr(const struct sockaddr_in *to, struct sockaddr_in *from)
{
static char errbuf[256];
int fd;
struct {
struct nlmsghdr n;
struct rtmsg r;
char data[1024];
} req;
struct rtattr *attr;
int len;
struct sockaddr_nl addr;
fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
if (fd < 0) {
sprintf(
errbuf, "cannot open netlink socket: %.128s",
strerror(errno)
);
return errbuf;
}
memset(&req, 0, sizeof(req));
req.n.nlmsg_len =
NLMSG_SPACE(sizeof(req.r)) +
RTA_LENGTH(sizeof(to->sin_addr));
req.n.nlmsg_flags = NLM_F_REQUEST;
req.n.nlmsg_type = RTM_GETROUTE;
req.r.rtm_family = AF_INET;
req.r.rtm_dst_len = 32;
attr = (void *) (((char *) &req) + NLMSG_SPACE(sizeof(req.r)));
attr->rta_type = RTA_DST;
attr->rta_len = RTA_LENGTH(sizeof(to->sin_addr));
memcpy(RTA_DATA(attr), &to->sin_addr, sizeof(to->sin_addr));
if (TEMP_FAILURE_RETRY(write(fd, &req, req.n.nlmsg_len)) < 0) {
sprintf(
errbuf, "error sending netlink message: %.128s",
strerror(errno)
);
err:
close(fd);
return errbuf;
}
do {
socklen_t alen = sizeof(addr);
len = TEMP_FAILURE_RETRY(
recvfrom(fd, &req, sizeof(req), 0,
(void *)&addr, &alen)
);
if (len < 0) {
sprintf(
errbuf,
"error receiving netlink message: %.128s",
strerror(errno)
);
goto err;
}
} while (addr.nl_pid);
close(fd);
if (req.n.nlmsg_type == NLMSG_ERROR) {
struct nlmsgerr *err = (struct nlmsgerr *) NLMSG_DATA(&req.n);
sprintf(
errbuf, "netlink error: %.128s",
strerror(-err->error)
);
return errbuf;
}
len -= NLMSG_SPACE(sizeof(req.r));
while (len > 0) {
uint32_t addr;
if (
attr->rta_type == RTA_PREFSRC &&
RTA_PAYLOAD(attr) == sizeof(addr)
) {
memcpy(&addr, RTA_DATA(attr), RTA_PAYLOAD(attr));
setsin(from, addr);
return 0;
}
attr = RTA_NEXT(attr, len);
}
strcpy(errbuf, "netlink did not return a source address");
return errbuf;
}
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