/usr.bin/talk/get_iface.c
https://bitbucket.org/freebsd/freebsd-head/ · C · 100 lines · 48 code · 16 blank · 36 comment · 10 complexity · 3b75d88d30f7c72fccba9ebde37bda0b MD5 · raw file
- /*
- * Copyright 1994, 1995 Massachusetts Institute of Technology
- *
- * Permission to use, copy, modify, and distribute this software and
- * its documentation for any purpose and without fee is hereby
- * granted, provided that both the above copyright notice and this
- * permission notice appear in all copies, that both the above
- * copyright notice and this permission notice appear in all
- * supporting documentation, and that the name of M.I.T. not be used
- * in advertising or publicity pertaining to distribution of the
- * software without specific, written prior permission. M.I.T. makes
- * no representations about the suitability of this software for any
- * purpose. It is provided "as is" without express or implied
- * warranty.
- *
- * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''. M.I.T. DISCLAIMS
- * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
- * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
- * SHALL M.I.T. 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.
- */
- #include <sys/cdefs.h>
- __FBSDID("$FreeBSD$");
- /*
- * From:
- * Id: find_interface.c,v 1.1 1995/08/14 16:08:39 wollman Exp
- */
- #include <errno.h>
- #include <string.h>
- #include <unistd.h>
- #include "talk.h"
- /*
- * Try to find the interface address that is used to route an IP
- * packet to a remote peer.
- */
- int
- get_iface(struct in_addr *dst, struct in_addr *iface)
- {
- static struct sockaddr_in local;
- struct sockaddr_in remote;
- socklen_t namelen;
- int s, rv;
- memcpy(&remote.sin_addr, dst, sizeof remote.sin_addr);
- remote.sin_port = htons(60000);
- remote.sin_family = AF_INET;
- remote.sin_len = sizeof remote;
- local.sin_addr.s_addr = htonl(INADDR_ANY);
- local.sin_port = htons(60000);
- local.sin_family = AF_INET;
- local.sin_len = sizeof local;
- s = socket(PF_INET, SOCK_DGRAM, 0);
- if (s < 0)
- return -1;
- do {
- rv = bind(s, (struct sockaddr *)&local, sizeof local);
- local.sin_port = htons(ntohs(local.sin_port) + 1);
- } while(rv < 0 && errno == EADDRINUSE);
- if (rv < 0) {
- close(s);
- return -1;
- }
- do {
- rv = connect(s, (struct sockaddr *)&remote, sizeof remote);
- remote.sin_port = htons(ntohs(remote.sin_port) + 1);
- } while(rv < 0 && errno == EADDRINUSE);
- if (rv < 0) {
- close(s);
- return -1;
- }
- namelen = sizeof local;
- rv = getsockname(s, (struct sockaddr *)&local, &namelen);
- close(s);
- if (rv < 0)
- return -1;
- memcpy(iface, &local.sin_addr, sizeof local.sin_addr);
- return 0;
- }