1 files changed, 108 insertions, 0 deletions
diff --git a/release/src/router/busybox/networking/udhcp/clientsocket.c b/release/src/router/busybox/networking/udhcp/clientsocket.c
new file mode 100644
index 00000000..1dcc1057
--- /dev/null
+++ b/release/src/router/busybox/networking/udhcp/clientsocket.c
@@ -0,0 +1,108 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * clientsocket.c -- DHCP client socket creation
+ *
+ * udhcp client
+ *
+ * Russ Dill <Russ.Dill@asu.edu> July 2001
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <features.h>
+#include <asm/types.h>
+#if (defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1) || defined(_NEWLIB_VERSION)
+#include <netpacket/packet.h>
+#include <net/ethernet.h>
+#else
+#include <linux/if_packet.h>
+#include <linux/if_ether.h>
+#endif
+#include <linux/filter.h>
+
+#include "common.h"
+#include "dhcpd.h"
+#include "dhcpc.h"
+
+int FAST_FUNC udhcp_raw_socket(int ifindex)
+{
+	int fd;
+	struct sockaddr_ll sock;
+
+	/*
+	 * Comment:
+	 *
+	 *	I've selected not to see LL header, so BPF doesn't see it, too.
+	 *	The filter may also pass non-IP and non-ARP packets, but we do
+	 *	a more complete check when receiving the message in userspace.
+	 *
+	 * and filter shamelessly stolen from:
+	 *
+	 *	http://www.flamewarmaster.de/software/dhcpclient/
+	 *
+	 * There are a few other interesting ideas on that page (look under
+	 * "Motivation").  Use of netlink events is most interesting.  Think
+	 * of various network servers listening for events and reconfiguring.
+	 * That would obsolete sending HUP signals and/or make use of restarts.
+	 *
+	 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
+	 * License: GPL v2.
+	 *
+	 * TODO: make conditional?
+	 */
+#define SERVER_AND_CLIENT_PORTS  ((67 << 16) + 68)
+	static const struct sock_filter filter_instr[] = {
+		/* check for udp */
+		BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
+		BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 2, 0),     /* L5, L1, is UDP? */
+		/* ugly check for arp on ethernet-like and IPv4 */
+		BPF_STMT(BPF_LD|BPF_W|BPF_ABS, 2),                      /* L1: */
+		BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 0x08000604, 3, 4),      /* L3, L4 */
+		/* skip IP header */
+		BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),                     /* L5: */
+		/* check udp source and destination ports */
+		BPF_STMT(BPF_LD|BPF_W|BPF_IND, 0),
+		BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, SERVER_AND_CLIENT_PORTS, 0, 1),	/* L3, L4 */
+		/* returns */
+		BPF_STMT(BPF_RET|BPF_K, 0x0fffffff ),                   /* L3: pass */
+		BPF_STMT(BPF_RET|BPF_K, 0),                             /* L4: reject */
+	};
+	static const struct sock_fprog filter_prog = {
+		.len = sizeof(filter_instr) / sizeof(filter_instr[0]),
+		/* casting const away: */
+		.filter = (struct sock_filter *) filter_instr,
+	};
+
+	DEBUG("opening raw socket on ifindex %d", ifindex);
+
+	fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
+	DEBUG("got raw socket fd %d", fd);
+
+	if (SERVER_PORT == 67 && CLIENT_PORT == 68) {
+		/* Use only if standard ports are in use */
+		/* Ignoring error (kernel may lack support for this) */
+		if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
+				sizeof(filter_prog)) >= 0)
+			DEBUG("attached filter to raw socket fd %d", fd);
+	}
+
+	sock.sll_family = AF_PACKET;
+	sock.sll_protocol = htons(ETH_P_IP);
+	sock.sll_ifindex = ifindex;
+	xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
+	DEBUG("bound to raw socket fd %d", fd);
+
+	return fd;
+}