1 files changed, 100 insertions, 0 deletions
diff --git a/usr.bin/talk/get_iface.c b/usr.bin/talk/get_iface.c
new file mode 100644
index 0000000..96d3d6e
--- /dev/null
+++ b/usr.bin/talk/get_iface.c
@@ -0,0 +1,100 @@
+/*
+ * 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;
+}