From e53738558f2f1aa8cd536545479ab98b0df808c5 Mon Sep 17 00:00:00 2001
From: Denis Vlasenko <vda.linux@googlemail.com>
Date: Wed, 10 Dec 2008 11:12:16 +0000
Subject: [PATCH] *: fix SO_BINDTODEVICE. Kernel wants at least IFNAMSIZ bytes
 there.

---
 include/libbb.h           |  1 +
 libbb/xconnect.c          | 15 +++++++++++++++
 networking/arping.c       |  3 +--
 networking/ping.c         |  4 ++--
 networking/udhcp/socket.c |  4 ++--
 5 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/include/libbb.h b/include/libbb.h
index 16e8f48db..e6767e39e 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -437,6 +437,7 @@ ssize_t xsendto(int s, const void *buf, size_t len, const struct sockaddr *to,
  * Turn it on before you call bind(). */
 void setsockopt_reuseaddr(int fd) FAST_FUNC; /* On Linux this never fails. */
 int setsockopt_broadcast(int fd) FAST_FUNC;
+int setsockopt_bindtodevice(int fd, const char *iface) FAST_FUNC;
 /* NB: returns port in host byte order */
 unsigned bb_lookup_port(const char *port, const char *protocol, unsigned default_port) FAST_FUNC;
 typedef struct len_and_sockaddr {
diff --git a/libbb/xconnect.c b/libbb/xconnect.c
index 5be83241b..d078e9811 100644
--- a/libbb/xconnect.c
+++ b/libbb/xconnect.c
@@ -8,6 +8,7 @@
  */
 
 #include <netinet/in.h>
+#include <net/if.h>
 #include "libbb.h"
 
 void FAST_FUNC setsockopt_reuseaddr(int fd)
@@ -18,6 +19,20 @@ int FAST_FUNC setsockopt_broadcast(int fd)
 {
 	return setsockopt(fd, SOL_SOCKET, SO_BROADCAST, &const_int_1, sizeof(const_int_1));
 }
+int FAST_FUNC setsockopt_bindtodevice(int fd, const char *iface)
+{
+	int r;
+	struct ifreq ifr;
+	strncpy_IFNAMSIZ(ifr.ifr_name, iface);
+	/* Actually, ifr_name is at offset 0, and in practice
+	 * just giving char[IFNAMSIZ] instead of struct ifreq works too.
+	 * But just in case it's not true on some obscure arch... */
+	r = setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, &ifr, sizeof(ifr));
+	if (r)
+		bb_perror_msg("can't bind to interface %s", iface);
+	return r;
+}
+
 
 void FAST_FUNC xconnect(int s, const struct sockaddr *s_addr, socklen_t addrlen)
 {
diff --git a/networking/arping.c b/networking/arping.c
index e7b842f5b..915af3261 100644
--- a/networking/arping.c
+++ b/networking/arping.c
@@ -331,8 +331,7 @@ int arping_main(int argc UNUSED_PARAM, char **argv)
 		struct sockaddr_in saddr;
 		int probe_fd = xsocket(AF_INET, SOCK_DGRAM, 0);
 
-		if (setsockopt(probe_fd, SOL_SOCKET, SO_BINDTODEVICE, device, strlen(device) + 1) == -1)
-			bb_perror_msg("cannot bind to device %s", device);
+		setsockopt_bindtodevice(probe_fd, device);
 		memset(&saddr, 0, sizeof(saddr));
 		saddr.sin_family = AF_INET;
 		if (src.s_addr) {
diff --git a/networking/ping.c b/networking/ping.c
index 01a9f9ac5..f2a612fde 100644
--- a/networking/ping.c
+++ b/networking/ping.c
@@ -572,7 +572,7 @@ static void ping4(len_and_sockaddr *lsa)
 		xbind(pingsock, &source_lsa->u.sa, source_lsa->len);
 	}
 	if (str_I)
-		setsockopt(pingsock, SOL_SOCKET, SO_BINDTODEVICE, str_I, strlen(str_I) + 1);
+		setsockopt_bindtodevice(pingsock, str_I);
 
 	/* enable broadcast pings */
 	setsockopt_broadcast(pingsock);
@@ -622,7 +622,7 @@ static void ping6(len_and_sockaddr *lsa)
 	if (source_lsa)
 		xbind(pingsock, &source_lsa->u.sa, source_lsa->len);
 	if (str_I)
-		setsockopt(pingsock, SOL_SOCKET, SO_BINDTODEVICE, str_I, strlen(str_I) + 1);
+		setsockopt_bindtodevice(pingsock, str_I);
 
 #ifdef ICMP6_FILTER
 	{
diff --git a/networking/udhcp/socket.c b/networking/udhcp/socket.c
index 857f0a4de..fdb558db4 100644
--- a/networking/udhcp/socket.c
+++ b/networking/udhcp/socket.c
@@ -98,8 +98,8 @@ int FAST_FUNC udhcp_listen_socket(/*uint32_t ip,*/ int port, const char *inf)
 		bb_perror_msg_and_die("SO_BROADCAST");
 
 	/* NB: bug 1032 says this doesn't work on ethernet aliases (ethN:M) */
-	if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, &inf, strlen(inf) + 1) == -1)
-		bb_perror_msg_and_die("SO_BINDTODEVICE");
+	if (setsockopt_bindtodevice(fd, inf))
+		xfunc_die(); /* warning is already printed */
 
 	memset(&addr, 0, sizeof(addr));
 	addr.sin_family = AF_INET;