[dragonfly.git] / sbin / dhclient / bpf.c

/*	$OpenBSD: bpf.c,v 1.20 2007/01/08 02:51:13 krw Exp $	*/
/*	$DragonFly: src/sbin/dhclient/bpf.c,v 1.2 2008/11/05 14:08:41 sephe Exp $	*/

/* BPF socket interface code, originally contributed by Archie Cobbs. */

/*
 * Copyright (c) 1995, 1996, 1998, 1999
 * The Internet Software Consortium.    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. Neither the name of The Internet Software Consortium nor the names
 *    of its contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM 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 INTERNET SOFTWARE CONSORTIUM 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.
 *
 * This software has been written for the Internet Software Consortium
 * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
 * Enterprises.  To learn more about the Internet Software Consortium,
 * see ``http://www.vix.com/isc''.  To learn more about Vixie
 * Enterprises, see ``http://www.vix.com''.
 */

#include <sys/ioctl.h>
#include <sys/uio.h>

#include <net/bpf.h>
#include <netinet/if_ether.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/udp.h>

#include "dhcpd.h"

/*
 * Called by get_interface_list for each interface that's discovered.
 * Opens a packet filter for each interface and adds it to the select
 * mask.
 */
int
if_register_bpf(void)
{
	char filename[50];
	int sock, b;

	/*
	 * Open a BPF device.  Try auto-clone first (newer kernels),
	 * otherwise iterate (older kernels).
	 */
	sock = open("/dev/bpf", O_RDWR, 0);
	if (sock < 0) {
		for (b = 0; 1; b++) {
			snprintf(filename, sizeof(filename), "/dev/bpf%d", b);
			sock = open(filename, O_RDWR, 0);
			if (sock < 0) {
				if (errno == EBUSY)
					continue;
				else
					error("Can't find free bpf: %m");
			} else {
				break;
			}
		}
	}

	/* Set the BPF device to point at this interface. */
	if (ioctl(sock, BIOCSETIF, ifi->ifp) < 0)
		error("Can't attach interface %s to bpf device %s: %m",
		    ifi->name, filename);

	return (sock);
}

void
if_register_send(void)
{
	int sock, on = 1;

	/*
	 * If we're using the bpf API for sending and receiving, we
	 * don't need to register this interface twice.
	 */
	ifi->wfdesc = ifi->rfdesc;

	/*
	 * Use raw socket for unicast send.
	 */
	if ((sock = socket(AF_INET, SOCK_RAW, IPPROTO_UDP)) == -1)
		error("socket(SOCK_RAW): %m");
	if (setsockopt(sock, IPPROTO_IP, IP_HDRINCL, &on,
	    sizeof(on)) == -1)
		error("setsockopt(IP_HDRINCL): %m");
	ifi->ufdesc = sock;
}

/*
 * Packet filter program...
 *
 * XXX: Changes to the filter program may require changes to the
 * constant offsets used in if_register_send to patch the BPF program!
 */
struct bpf_insn dhcp_bpf_filter[] = {
	/* Make sure this is an IP packet... */
	BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12),
	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 8),

	/* Make sure it's a UDP packet... */
	BPF_STMT(BPF_LD + BPF_B + BPF_ABS, 23),
	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 0, 6),

	/* Make sure this isn't a fragment... */
	BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20),
	BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x1fff, 4, 0),

	/* Get the IP header length... */
	BPF_STMT(BPF_LDX + BPF_B + BPF_MSH, 14),

	/* Make sure it's to the right port... */
	BPF_STMT(BPF_LD + BPF_H + BPF_IND, 16),
	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 67, 0, 1),		/* patch */

	/* If we passed all the tests, ask for the whole packet. */
	BPF_STMT(BPF_RET+BPF_K, (u_int)-1),

	/* Otherwise, drop it. */
	BPF_STMT(BPF_RET+BPF_K, 0),
};

int dhcp_bpf_filter_len = sizeof(dhcp_bpf_filter) / sizeof(struct bpf_insn);

/*
 * Packet write filter program:
 * 'ip and udp and src port bootps and dst port (bootps or bootpc)'
 */
struct bpf_insn dhcp_bpf_wfilter[] = {
	BPF_STMT(BPF_LD + BPF_B + BPF_IND, 14),
	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, (IPVERSION << 4) + 5, 0, 12),

	/* Make sure this is an IP packet... */
	BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12),
	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 10),

	/* Make sure it's a UDP packet... */
	BPF_STMT(BPF_LD + BPF_B + BPF_ABS, 23),
	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 0, 8),

	/* Make sure this isn't a fragment... */
	BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20),
	BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x1fff, 6, 0),	/* patched */

	/* Get the IP header length... */
	BPF_STMT(BPF_LDX + BPF_B + BPF_MSH, 14),

	/* Make sure it's from the right port... */
	BPF_STMT(BPF_LD + BPF_H + BPF_IND, 14),
	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 68, 0, 3),

	/* Make sure it is to the right ports ... */
	BPF_STMT(BPF_LD + BPF_H + BPF_IND, 16),
	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 67, 0, 1),

	/* If we passed all the tests, ask for the whole packet. */
	BPF_STMT(BPF_RET+BPF_K, (u_int)-1),

	/* Otherwise, drop it. */
	BPF_STMT(BPF_RET+BPF_K, 0),
};

int dhcp_bpf_wfilter_len = sizeof(dhcp_bpf_wfilter) / sizeof(struct bpf_insn);

void
if_register_receive(void)
{
	struct bpf_version v;
	struct bpf_program p;
	int flag = 1, sz;

	/* Open a BPF device and hang it on this interface... */
	ifi->rfdesc = if_register_bpf();

	/* Make sure the BPF version is in range... */
	if (ioctl(ifi->rfdesc, BIOCVERSION, &v) < 0)
		error("Can't get BPF version: %m");

	if (v.bv_major != BPF_MAJOR_VERSION ||
	    v.bv_minor < BPF_MINOR_VERSION)
		error("Kernel BPF version out of range - recompile dhcpd!");

	/*
	 * Set immediate mode so that reads return as soon as a packet
	 * comes in, rather than waiting for the input buffer to fill
	 * with packets.
	 */
	if (ioctl(ifi->rfdesc, BIOCIMMEDIATE, &flag) < 0)
		error("Can't set immediate mode on bpf device: %m");

	/*if (ioctl(ifi->rfdesc, BIOCSFILDROP, &flag) < 0)
		error("Can't set filter-drop mode on bpf device: %m");*/

	/* Get the required BPF buffer length from the kernel. */
	if (ioctl(ifi->rfdesc, BIOCGBLEN, &sz) < 0)
		error("Can't get bpf buffer length: %m");
	ifi->rbuf_max = sz;
	ifi->rbuf = malloc(ifi->rbuf_max);
	if (!ifi->rbuf)
		error("Can't allocate %lu bytes for bpf input buffer.",
		    (unsigned long)ifi->rbuf_max);
	ifi->rbuf_offset = 0;
	ifi->rbuf_len = 0;

	/* Set up the bpf filter program structure. */
	p.bf_len = dhcp_bpf_filter_len;
	p.bf_insns = dhcp_bpf_filter;

	/* Patch the server port into the BPF program...
	 *
	 * XXX: changes to filter program may require changes to the
	 * insn number(s) used below!
	 */
	dhcp_bpf_filter[8].k = LOCAL_PORT;

	if (ioctl(ifi->rfdesc, BIOCSETF, &p) < 0)
		error("Can't install packet filter program: %m");

	/* Set up the bpf write filter program structure. */
	p.bf_len = dhcp_bpf_wfilter_len;
	p.bf_insns = dhcp_bpf_wfilter;

	if (dhcp_bpf_wfilter[7].k == 0x1fff)
		dhcp_bpf_wfilter[7].k = htons(IP_MF|IP_OFFMASK);

	if (ioctl(ifi->rfdesc, BIOCSETWF, &p) < 0)
		error("Can't install write filter program: %m");

	if (ioctl(ifi->rfdesc, BIOCLOCK, NULL) < 0)
		error("Cannot lock bpf");
}

ssize_t
send_packet(struct in_addr from, struct sockaddr_in *to,
    struct hardware *hto)
{
#define IOVCNT		2
	unsigned char buf[256];
	struct iovec iov[IOVCNT];
	struct msghdr msg;
	int result, bufp = 0;

	if (to->sin_addr.s_addr == INADDR_BROADCAST) {
		assemble_hw_header(buf, &bufp, hto);
	}

	assemble_udp_ip_header(buf, &bufp, from.s_addr,
	    to->sin_addr.s_addr, to->sin_port,
	    (unsigned char *)&client->packet,
	    client->packet_length);

	iov[0].iov_base = (char *)buf;
	iov[0].iov_len = bufp;
	iov[1].iov_base = (char *)&client->packet;
	iov[1].iov_len = client->packet_length;

	if (to->sin_addr.s_addr == INADDR_BROADCAST) {
		result = writev(ifi->wfdesc, iov, IOVCNT);
	} else {
		struct ip *ip = (struct ip *)buf;

		/*
		 * DragonFly's raw socket expects ip_len/ip_off
		 * in host byte order.
		 */
		ip->ip_len = ntohs(ip->ip_len);
		ip->ip_off = ntohs(ip->ip_off);

		memset(&msg, 0, sizeof(msg));
		msg.msg_name = (struct sockaddr *)to;
		msg.msg_namelen = sizeof(*to);
		msg.msg_iov = iov;
		msg.msg_iovlen = IOVCNT;
		result = sendmsg(ifi->ufdesc, &msg, 0);
	}

	if (result == -1)
		warning("send_packet: %m");
	return (result);
}

ssize_t
receive_packet(struct sockaddr_in *from, struct hardware *hfrom)
{
	int length = 0, offset = 0;
	struct bpf_hdr hdr;

	/*
	 * All this complexity is because BPF doesn't guarantee that
	 * only one packet will be returned at a time.  We're getting
	 * what we deserve, though - this is a terrible abuse of the BPF
	 * interface.  Sigh.
	 */

	/* Process packets until we get one we can return or until we've
	 * done a read and gotten nothing we can return...
	 */
	do {
		/* If the buffer is empty, fill it. */
		if (ifi->rbuf_offset >= ifi->rbuf_len) {
			length = read(ifi->rfdesc, ifi->rbuf, ifi->rbuf_max);
			if (length <= 0)
				return (length);
			ifi->rbuf_offset = 0;
			ifi->rbuf_len = BPF_WORDALIGN(length);
		}

		/*
		 * If there isn't room for a whole bpf header, something
		 * went wrong, but we'll ignore it and hope it goes
		 * away... XXX
		 */
		if (ifi->rbuf_len - ifi->rbuf_offset < sizeof(hdr)) {
			ifi->rbuf_offset = ifi->rbuf_len;
			continue;
		}

		/* Copy out a bpf header... */
		memcpy(&hdr, &ifi->rbuf[ifi->rbuf_offset], sizeof(hdr));

		/*
		 * If the bpf header plus data doesn't fit in what's
		 * left of the buffer, stick head in sand yet again...
		 */
		if (ifi->rbuf_offset + hdr.bh_hdrlen + hdr.bh_caplen >
		    ifi->rbuf_len) {
			ifi->rbuf_offset = ifi->rbuf_len;
			continue;
		}

		/*
		 * If the captured data wasn't the whole packet, or if
		 * the packet won't fit in the input buffer, all we can
		 * do is drop it.
		 */
		if (hdr.bh_caplen != hdr.bh_datalen) {
			ifi->rbuf_offset = BPF_WORDALIGN(
			    ifi->rbuf_offset + hdr.bh_hdrlen +
			    hdr.bh_caplen);
			continue;
		}

		/* Skip over the BPF header... */
		ifi->rbuf_offset += hdr.bh_hdrlen;

		/* Decode the physical header... */
		offset = decode_hw_header(ifi->rbuf, ifi->rbuf_offset, hfrom);

		/*
		 * If a physical layer checksum failed (dunno of any
		 * physical layer that supports this, but WTH), skip
		 * this packet.
		 */
		if (offset < 0) {
			ifi->rbuf_offset = BPF_WORDALIGN(
			    ifi->rbuf_offset + hdr.bh_caplen);
			continue;
		}
		ifi->rbuf_offset += offset;
		hdr.bh_caplen -= offset;

		/* Decode the IP and UDP headers... */
		offset = decode_udp_ip_header(ifi->rbuf,
		    ifi->rbuf_offset, from, NULL, hdr.bh_caplen);

		/* If the IP or UDP checksum was bad, skip the packet... */
		if (offset < 0) {
			ifi->rbuf_offset = BPF_WORDALIGN(
			    ifi->rbuf_offset + hdr.bh_caplen);
			continue;
		}
		ifi->rbuf_offset += offset;
		hdr.bh_caplen -= offset;

		/*
		 * If there's not enough room to stash the packet data,
		 * we have to skip it (this shouldn't happen in real
		 * life, though).
		 */
		if (hdr.bh_caplen > sizeof(client->packet)) {
			ifi->rbuf_offset = BPF_WORDALIGN(
			    ifi->rbuf_offset + hdr.bh_caplen);
			continue;
		}

		/* Copy out the data in the packet... */
		memset(&client->packet, DHO_END, sizeof(client->packet));
		memcpy(&client->packet, ifi->rbuf + ifi->rbuf_offset,
		    hdr.bh_caplen);
		ifi->rbuf_offset = BPF_WORDALIGN(ifi->rbuf_offset +
		    hdr.bh_caplen);
		return (hdr.bh_caplen);
	} while (!length);
	return (0);
}
Commit	Line	Data
846204b6	1	/* $OpenBSD: bpf.c,v 1.20 2007/01/08 02:51:13 krw Exp $ */
c02c89a7	2	/* $DragonFly: src/sbin/dhclient/bpf.c,v 1.2 2008/11/05 14:08:41 sephe Exp $ */
846204b6 HT	3
	4	/* BPF socket interface code, originally contributed by Archie Cobbs. */
	5
	6	/*
	7	* Copyright (c) 1995, 1996, 1998, 1999
	8	* The Internet Software Consortium. All rights reserved.
	9	*
	10	* Redistribution and use in source and binary forms, with or without
	11	* modification, are permitted provided that the following conditions
	12	* are met:
	13	*
	14	* 1. Redistributions of source code must retain the above copyright
	15	* notice, this list of conditions and the following disclaimer.
	16	* 2. Redistributions in binary form must reproduce the above copyright
	17	* notice, this list of conditions and the following disclaimer in the
	18	* documentation and/or other materials provided with the distribution.
	19	* 3. Neither the name of The Internet Software Consortium nor the names
	20	* of its contributors may be used to endorse or promote products derived
	21	* from this software without specific prior written permission.
	22	*
	23	* THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
	24	* CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
	25	* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
	26	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
	27	* DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
	28	* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	29	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	30	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
	31	* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
	32	* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
	33	* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
	34	* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	35	* SUCH DAMAGE.
	36	*
	37	* This software has been written for the Internet Software Consortium
	38	* by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
	39	* Enterprises. To learn more about the Internet Software Consortium,
	40	* see ``http://www.vix.com/isc''. To learn more about Vixie
	41	* Enterprises, see ``http://www.vix.com''.
	42	*/
	43
	44	#include <sys/ioctl.h>
	45	#include <sys/uio.h>
	46
	47	#include <net/bpf.h>
	48	#include <netinet/if_ether.h>
	49	#include <netinet/in_systm.h>
	50	#include <netinet/ip.h>
	51	#include <netinet/udp.h>
	52
	53	#include "dhcpd.h"
	54
846204b6 HT	55	/*
	56	* Called by get_interface_list for each interface that's discovered.
	57	* Opens a packet filter for each interface and adds it to the select
	58	* mask.
	59	*/
	60	int
	61	if_register_bpf(void)
	62	{
	63	char filename[50];
	64	int sock, b;
	65
45e80934 MD	66	/*
	67	* Open a BPF device. Try auto-clone first (newer kernels),
	68	* otherwise iterate (older kernels).
	69	*/
	70	sock = open("/dev/bpf", O_RDWR, 0);
	71	if (sock < 0) {
	72	for (b = 0; 1; b++) {
	73	snprintf(filename, sizeof(filename), "/dev/bpf%d", b);
	74	sock = open(filename, O_RDWR, 0);
	75	if (sock < 0) {
	76	if (errno == EBUSY)
	77	continue;
	78	else
	79	error("Can't find free bpf: %m");
	80	} else {
	81	break;
	82	}
	83	}
846204b6 HT	84	}
	85
	86	/* Set the BPF device to point at this interface. */
	87	if (ioctl(sock, BIOCSETIF, ifi->ifp) < 0)
	88	error("Can't attach interface %s to bpf device %s: %m",
	89	ifi->name, filename);
	90
	91	return (sock);
	92	}
	93
	94	void
	95	if_register_send(void)
	96	{
	97	int sock, on = 1;
	98
	99	/*
	100	* If we're using the bpf API for sending and receiving, we
	101	* don't need to register this interface twice.
	102	*/
	103	ifi->wfdesc = ifi->rfdesc;
	104
	105	/*
	106	* Use raw socket for unicast send.
	107	*/
	108	if ((sock = socket(AF_INET, SOCK_RAW, IPPROTO_UDP)) == -1)
	109	error("socket(SOCK_RAW): %m");
	110	if (setsockopt(sock, IPPROTO_IP, IP_HDRINCL, &on,
	111	sizeof(on)) == -1)
	112	error("setsockopt(IP_HDRINCL): %m");
	113	ifi->ufdesc = sock;
	114	}
	115
	116	/*
	117	* Packet filter program...
	118	*
	119	* XXX: Changes to the filter program may require changes to the
	120	* constant offsets used in if_register_send to patch the BPF program!
	121	*/
	122	struct bpf_insn dhcp_bpf_filter[] = {
	123	/* Make sure this is an IP packet... */
	124	BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12),
	125	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 8),
	126
	127	/* Make sure it's a UDP packet... */
	128	BPF_STMT(BPF_LD + BPF_B + BPF_ABS, 23),
	129	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 0, 6),
	130
	131	/* Make sure this isn't a fragment... */
	132	BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20),
	133	BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x1fff, 4, 0),
	134
	135	/* Get the IP header length... */
	136	BPF_STMT(BPF_LDX + BPF_B + BPF_MSH, 14),
	137
	138	/* Make sure it's to the right port... */
	139	BPF_STMT(BPF_LD + BPF_H + BPF_IND, 16),
	140	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 67, 0, 1), /* patch */
	141
	142	/* If we passed all the tests, ask for the whole packet. */
	143	BPF_STMT(BPF_RET+BPF_K, (u_int)-1),
	144
	145	/* Otherwise, drop it. */
	146	BPF_STMT(BPF_RET+BPF_K, 0),
	147	};
148
149	int dhcp_bpf_filter_len = sizeof(dhcp_bpf_filter) / sizeof(struct bpf_insn);
150
151	/*
152	* Packet write filter program:
153	* 'ip and udp and src port bootps and dst port (bootps or bootpc)'
154	*/
155	struct bpf_insn dhcp_bpf_wfilter[] = {
156	BPF_STMT(BPF_LD + BPF_B + BPF_IND, 14),
157	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, (IPVERSION << 4) + 5, 0, 12),
158
159	/* Make sure this is an IP packet... */
160	BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12),
161	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 10),
162
163	/* Make sure it's a UDP packet... */
164	BPF_STMT(BPF_LD + BPF_B + BPF_ABS, 23),
165	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 0, 8),
166
167	/* Make sure this isn't a fragment... */
168	BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20),
169	BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x1fff, 6, 0), /* patched */
170
171	/* Get the IP header length... */
172	BPF_STMT(BPF_LDX + BPF_B + BPF_MSH, 14),
173
174	/* Make sure it's from the right port... */
175	BPF_STMT(BPF_LD + BPF_H + BPF_IND, 14),
176	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 68, 0, 3),
177
178	/* Make sure it is to the right ports ... */
179	BPF_STMT(BPF_LD + BPF_H + BPF_IND, 16),
180	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 67, 0, 1),
181
182	/* If we passed all the tests, ask for the whole packet. */
183	BPF_STMT(BPF_RET+BPF_K, (u_int)-1),
184
185	/* Otherwise, drop it. */
186	BPF_STMT(BPF_RET+BPF_K, 0),
187	};
188
189	int dhcp_bpf_wfilter_len = sizeof(dhcp_bpf_wfilter) / sizeof(struct bpf_insn);
190
191	void
192	if_register_receive(void)
193	{
194	struct bpf_version v;
195	struct bpf_program p;
196	int flag = 1, sz;
197
198	/* Open a BPF device and hang it on this interface... */
199	ifi->rfdesc = if_register_bpf();
200
201	/* Make sure the BPF version is in range... */
202	if (ioctl(ifi->rfdesc, BIOCVERSION, &v) < 0)
203	error("Can't get BPF version: %m");
204
205	if (v.bv_major != BPF_MAJOR_VERSION \|\|
206	v.bv_minor < BPF_MINOR_VERSION)
207	error("Kernel BPF version out of range - recompile dhcpd!");
208
209	/*
210	* Set immediate mode so that reads return as soon as a packet
211	* comes in, rather than waiting for the input buffer to fill
212	* with packets.
213	*/
214	if (ioctl(ifi->rfdesc, BIOCIMMEDIATE, &flag) < 0)
215	error("Can't set immediate mode on bpf device: %m");
216
217	/*if (ioctl(ifi->rfdesc, BIOCSFILDROP, &flag) < 0)
218	error("Can't set filter-drop mode on bpf device: %m");*/
219
220	/* Get the required BPF buffer length from the kernel. */
221	if (ioctl(ifi->rfdesc, BIOCGBLEN, &sz) < 0)
222	error("Can't get bpf buffer length: %m");
223	ifi->rbuf_max = sz;
224	ifi->rbuf = malloc(ifi->rbuf_max);
225	if (!ifi->rbuf)
226	error("Can't allocate %lu bytes for bpf input buffer.",
227	(unsigned long)ifi->rbuf_max);
228	ifi->rbuf_offset = 0;
229	ifi->rbuf_len = 0;
230
231	/* Set up the bpf filter program structure. */
232	p.bf_len = dhcp_bpf_filter_len;
233	p.bf_insns = dhcp_bpf_filter;
234
235	/* Patch the server port into the BPF program...
236	*
237	* XXX: changes to filter program may require changes to the
238	* insn number(s) used below!
239	*/
240	dhcp_bpf_filter[8].k = LOCAL_PORT;
241
242	if (ioctl(ifi->rfdesc, BIOCSETF, &p) < 0)
243	error("Can't install packet filter program: %m");
244
245	/* Set up the bpf write filter program structure. */
246	p.bf_len = dhcp_bpf_wfilter_len;
247	p.bf_insns = dhcp_bpf_wfilter;
248
249	if (dhcp_bpf_wfilter[7].k == 0x1fff)
250	dhcp_bpf_wfilter[7].k = htons(IP_MF\|IP_OFFMASK);
251
252	if (ioctl(ifi->rfdesc, BIOCSETWF, &p) < 0)
253	error("Can't install write filter program: %m");
254
255	if (ioctl(ifi->rfdesc, BIOCLOCK, NULL) < 0)
256	error("Cannot lock bpf");
257	}
258
259	ssize_t
260	send_packet(struct in_addr from, struct sockaddr_in *to,
261	struct hardware *hto)
262	{
263	#define IOVCNT 2
264	unsigned char buf[256];
265	struct iovec iov[IOVCNT];
266	struct msghdr msg;
267	int result, bufp = 0;
268
269	if (to->sin_addr.s_addr == INADDR_BROADCAST) {
270	assemble_hw_header(buf, &bufp, hto);
271	}
272
273	assemble_udp_ip_header(buf, &bufp, from.s_addr,
274	to->sin_addr.s_addr, to->sin_port,
275	(unsigned char *)&client->packet,
276	client->packet_length);
277
278	iov[0].iov_base = (char *)buf;
279	iov[0].iov_len = bufp;
280	iov[1].iov_base = (char *)&client->packet;
281	iov[1].iov_len = client->packet_length;
282
283	if (to->sin_addr.s_addr == INADDR_BROADCAST) {
284	result = writev(ifi->wfdesc, iov, IOVCNT);
285	} else {
c02c89a7 SZ	286	struct ip ip = (struct ip )buf;
	287
	288	/*
	289	* DragonFly's raw socket expects ip_len/ip_off
	290	* in host byte order.
	291	*/
	292	ip->ip_len = ntohs(ip->ip_len);
	293	ip->ip_off = ntohs(ip->ip_off);
	294
846204b6 HT	295	memset(&msg, 0, sizeof(msg));
	296	msg.msg_name = (struct sockaddr *)to;
	297	msg.msg_namelen = sizeof(*to);
	298	msg.msg_iov = iov;
	299	msg.msg_iovlen = IOVCNT;
	300	result = sendmsg(ifi->ufdesc, &msg, 0);
	301	}
	302
	303	if (result == -1)
	304	warning("send_packet: %m");
	305	return (result);
	306	}
	307
	308	ssize_t
	309	receive_packet(struct sockaddr_in from, struct hardware hfrom)
	310	{
	311	int length = 0, offset = 0;
	312	struct bpf_hdr hdr;
	313
	314	/*
	315	* All this complexity is because BPF doesn't guarantee that
	316	* only one packet will be returned at a time. We're getting
	317	* what we deserve, though - this is a terrible abuse of the BPF
	318	* interface. Sigh.
	319	*/
	320
	321	/* Process packets until we get one we can return or until we've
	322	* done a read and gotten nothing we can return...
	323	*/
	324	do {
	325	/* If the buffer is empty, fill it. */
db2a0826	326	if (ifi->rbuf_offset >= ifi->rbuf_len) {
846204b6 HT	327	length = read(ifi->rfdesc, ifi->rbuf, ifi->rbuf_max);
	328	if (length <= 0)
	329	return (length);
	330	ifi->rbuf_offset = 0;
	331	ifi->rbuf_len = BPF_WORDALIGN(length);
	332	}
	333
	334	/*
	335	* If there isn't room for a whole bpf header, something
	336	* went wrong, but we'll ignore it and hope it goes
	337	* away... XXX
	338	*/
	339	if (ifi->rbuf_len - ifi->rbuf_offset < sizeof(hdr)) {
	340	ifi->rbuf_offset = ifi->rbuf_len;
	341	continue;
	342	}
	343
	344	/* Copy out a bpf header... */
	345	memcpy(&hdr, &ifi->rbuf[ifi->rbuf_offset], sizeof(hdr));
	346
	347	/*
	348	* If the bpf header plus data doesn't fit in what's
	349	* left of the buffer, stick head in sand yet again...
	350	*/
	351	if (ifi->rbuf_offset + hdr.bh_hdrlen + hdr.bh_caplen >
	352	ifi->rbuf_len) {
	353	ifi->rbuf_offset = ifi->rbuf_len;
	354	continue;
	355	}
	356
	357	/*
	358	* If the captured data wasn't the whole packet, or if
	359	* the packet won't fit in the input buffer, all we can
	360	* do is drop it.
	361	*/
	362	if (hdr.bh_caplen != hdr.bh_datalen) {
	363	ifi->rbuf_offset = BPF_WORDALIGN(
	364	ifi->rbuf_offset + hdr.bh_hdrlen +
	365	hdr.bh_caplen);
	366	continue;
	367	}
	368
	369	/* Skip over the BPF header... */
	370	ifi->rbuf_offset += hdr.bh_hdrlen;
	371
	372	/* Decode the physical header... */
	373	offset = decode_hw_header(ifi->rbuf, ifi->rbuf_offset, hfrom);
	374
	375	/*
	376	* If a physical layer checksum failed (dunno of any
	377	* physical layer that supports this, but WTH), skip
	378	* this packet.
	379	*/
	380	if (offset < 0) {
	381	ifi->rbuf_offset = BPF_WORDALIGN(
	382	ifi->rbuf_offset + hdr.bh_caplen);
	383	continue;
	384	}
	385	ifi->rbuf_offset += offset;
	386	hdr.bh_caplen -= offset;
	387
	388	/* Decode the IP and UDP headers... */
	389	offset = decode_udp_ip_header(ifi->rbuf,
	390	ifi->rbuf_offset, from, NULL, hdr.bh_caplen);
391
392	/* If the IP or UDP checksum was bad, skip the packet... */
393	if (offset < 0) {
394	ifi->rbuf_offset = BPF_WORDALIGN(
395	ifi->rbuf_offset + hdr.bh_caplen);
396	continue;
397	}
398	ifi->rbuf_offset += offset;
399	hdr.bh_caplen -= offset;
400
401	/*
402	* If there's not enough room to stash the packet data,
403	* we have to skip it (this shouldn't happen in real
404	* life, though).
405	*/
406	if (hdr.bh_caplen > sizeof(client->packet)) {
407	ifi->rbuf_offset = BPF_WORDALIGN(
408	ifi->rbuf_offset + hdr.bh_caplen);
409	continue;
410	}
411
412	/* Copy out the data in the packet... */
413	memset(&client->packet, DHO_END, sizeof(client->packet));
414	memcpy(&client->packet, ifi->rbuf + ifi->rbuf_offset,
415	hdr.bh_caplen);
416	ifi->rbuf_offset = BPF_WORDALIGN(ifi->rbuf_offset +
417	hdr.bh_caplen);
418	return (hdr.bh_caplen);
419	} while (!length);
420	return (0);
421	}