Head

GCC Code Coverage Report

Directory:	./		Exec	Total	Coverage
File:	usr.sbin/dhcrelay6/bpf.c	Lines:	0	135	0.0 %
Date:	2017-11-13	Branches:	0	56	0.0 %


/*	$OpenBSD: bpf.c,v 1.2 2017/04/19 05:36:13 natano 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/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>

#include <net/bpf.h>
#include <net/if.h>

#include <netinet/in.h>
#include <netinet/if_ether.h>

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "dhcp.h"
#include "dhcpd.h"
#include "log.h"

ssize_t send_packet_layer3(struct interface_info *,
    void *, size_t, struct packet_ctx *);

/*
 * 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(struct interface_info *info)
{
	int sock;

	/* Open the BPF device */
	if ((sock = open("/dev/bpf", O_RDWR)) == -1)
		fatal("Can't open bpf device");

	/* Set the BPF device to point at this interface. */
	if (ioctl(sock, BIOCSETIF, &info->ifr) == -1)
		fatal("Can't attach interface %s to bpf device", info->name);

	return (sock);
}

void
if_register_send(struct interface_info *info)
{
	/*
	 * If we're using the bpf API for sending and receiving, we
	 * don't need to register this interface twice.
	 */
	info->wfdesc = info->rfdesc;
}

/* DHCPv6 BPF filters. */

/*
 * Packet filter program: 'ip6 and udp and dst port DHCP6_SERVER_PORT'
 */
struct bpf_insn dhcp6_bpf_sfilter[] = {
	/* 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_IPV6, 0, 5),

	/* Make sure this is an UDP packet. */
	BPF_STMT(BPF_LD + BPF_B + BPF_ABS, 20),
	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 0, 3),

	/* Make sure it is the right port. */
	BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 56),
	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DHCP6_SERVER_PORT, 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 dhcp6_bpf_sfilter_len = sizeof(dhcp6_bpf_sfilter) / sizeof(struct bpf_insn);

/*
 * Packet filter program: 'ip6 and udp'
 */
struct bpf_insn dhcp6_bpf_wfilter[] = {
	/* 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_IPV6, 0, 3),

	/* Make sure this is an UDP packet. */
	BPF_STMT(BPF_LD + BPF_B + BPF_ABS, 20),
	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 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 dhcp6_bpf_wfilter_len = sizeof(dhcp6_bpf_wfilter) / sizeof(struct bpf_insn);


void
if_register_receive(struct interface_info *info)
{
	struct bpf_version v;
	struct bpf_program p;
	int flag = 1, sz, cmplt = 0;

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

	/* Make sure the BPF version is in range... */
	if (ioctl(info->rfdesc, BIOCVERSION, &v) == -1)
		fatal("Can't get BPF version");

	if (v.bv_major != BPF_MAJOR_VERSION ||
	    v.bv_minor < BPF_MINOR_VERSION)
		fatalx("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(info->rfdesc, BIOCIMMEDIATE, &flag) == -1)
		fatal("Can't set immediate mode on bpf device");

	/* make sure kernel fills in the source ethernet address */
	if (ioctl(info->rfdesc, BIOCSHDRCMPLT, &cmplt) == -1)
		fatal("Can't set header complete flag on bpf device");

	/* Get the required BPF buffer length from the kernel. */
	if (ioctl(info->rfdesc, BIOCGBLEN, &sz) == -1)
		fatal("Can't get bpf buffer length");
	info->rbuf_max = sz;
	info->rbuf = malloc(info->rbuf_max);
	if (!info->rbuf)
		fatalx("Can't allocate %lu bytes for bpf input buffer.",
		    (unsigned long)info->rbuf_max);
	info->rbuf_offset = 0;
	info->rbuf_len = 0;

	/* Set up the bpf filter program structure. */
	p.bf_len = dhcp6_bpf_sfilter_len;
	p.bf_insns = dhcp6_bpf_sfilter;
	if (ioctl(info->rfdesc, BIOCSETF, &p) == -1)
		fatal("Can't install packet filter program");

	/* Set up the bpf write filter program structure. */
	p.bf_len = dhcp6_bpf_wfilter_len;
	p.bf_insns = dhcp6_bpf_wfilter;
	if (ioctl(info->rfdesc, BIOCSETWF, &p) == -1)
		fatal("Can't install write filter program");

	/* Only get input packets. */
	flag = BPF_DIRECTION_OUT;
	if (ioctl(info->rfdesc, BIOCSDIRFILT , &flag) == -1)
		fatal("Can't set BPF direction capture");

	/* Drop them so they don't go up in the network stack. */
	flag = 1;
	if (ioctl(info->rfdesc, BIOCSFILDROP, &flag) == -1)
		fatal("Can't set BPF filter drop");

	/* make sure these settings cannot be changed after dropping privs */
	if (ioctl(info->rfdesc, BIOCLOCK) == -1)
		fatal("Failed to lock bpf descriptor");
}

ssize_t
send_packet_layer3(struct interface_info *intf, void *raw, size_t len,
    struct packet_ctx *pc)
{
	struct cmsghdr		*cmsg;
	ssize_t			 sendlen;
	struct msghdr		 msg;
	struct in6_pktinfo	*ipi6;
	struct sockaddr_storage	 ss;
	struct iovec		 iov[2];
	uint8_t			 cmsgbuf[
	    CMSG_SPACE(sizeof(struct in6_pktinfo))
	];

	log_debug("  sending %ld bytes to %s:%d via %s",
	    len, v6addr2str(&ss2sin6(&pc->pc_dst)->sin6_addr),
	    ntohs(ss2sin6(&pc->pc_dst)->sin6_port), intf->name);

	memset(&msg, 0, sizeof(msg));
	iov[0].iov_base = raw;
	iov[0].iov_len = len;
	msg.msg_iov = iov;
	msg.msg_iovlen = 1;

	ss = pc->pc_dst;
	ss2sin6(&ss)->sin6_scope_id = intf->index;
	msg.msg_name = &ss;
	msg.msg_namelen = ss.ss_len;

	/* If binded to multicast we should select an interface. */
	if (IN6_IS_ADDR_MULTICAST(&ss2sin6(&ss)->sin6_addr)) {
		memset(cmsgbuf, 0, sizeof(cmsgbuf));
		msg.msg_control = cmsgbuf;
		msg.msg_controllen = sizeof(cmsgbuf);

		/* Use the IPV6_PKTINFO to select the interface. */
		cmsg = (struct cmsghdr *)CMSG_FIRSTHDR(&msg);
		cmsg->cmsg_len = CMSG_LEN(sizeof(*ipi6));
		cmsg->cmsg_level = IPPROTO_IPV6;
		cmsg->cmsg_type = IPV6_PKTINFO;

		ipi6 = (struct in6_pktinfo *)CMSG_DATA(cmsg);
		ipi6->ipi6_ifindex = intf->index;
	}

	if ((sendlen = sendmsg(pc->pc_sd, &msg, 0)) == -1) {
		log_warn("  failed to send message");
		return -1;
	}
	if (sendlen < (ssize_t)len)
		log_warnx("  sent less bytes than expected (%ld < %ld)",
		    sendlen, len);

	return sendlen;
}

ssize_t
send_packet(struct interface_info *interface,
    void *raw, size_t len, struct packet_ctx *pc)
{
	unsigned char buf[256];
	struct iovec iov[2];
	int result, bufp = 0;

	if (pc->pc_sd != 0)
		return send_packet_layer3(interface, raw, len, pc);

	/* Assemble the headers... */
	assemble_hw_header(buf, &bufp, pc);
	assemble_udp_ip6_header(buf, &bufp, pc, raw, len);

	/* Fire it off */
	iov[0].iov_base = (char *)buf;
	iov[0].iov_len = bufp;
	iov[1].iov_base = (char *)raw;
	iov[1].iov_len = len;

	result = writev(interface->wfdesc, iov, 2);
	if (result == -1)
		log_warn("send_packet");

	return (result);
}

ssize_t
receive_packet(struct interface_info *interface, unsigned char *buf,
    size_t len, struct packet_ctx *pc)
{
	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 (interface->rbuf_offset == interface->rbuf_len) {
			length = read(interface->rfdesc, interface->rbuf,
			    interface->rbuf_max);
			if (length <= 0)
				return (length);
			interface->rbuf_offset = 0;
			interface->rbuf_len = 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 (interface->rbuf_len - interface->rbuf_offset <
		    sizeof(hdr)) {
			interface->rbuf_offset = interface->rbuf_len;
			continue;
		}

		/* Copy out a bpf header... */
		memcpy(&hdr, &interface->rbuf[interface->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 (interface->rbuf_offset + hdr.bh_hdrlen + hdr.bh_caplen >
		    interface->rbuf_len) {
			interface->rbuf_offset = interface->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) {
			interface->rbuf_offset += hdr.bh_hdrlen =
			    hdr.bh_caplen;
			continue;
		}

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

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

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

		/* Decode the IP and UDP headers... */
		offset = decode_udp_ip6_header(interface->rbuf,
		    interface->rbuf_offset, pc, hdr.bh_caplen);

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

		/* Copy out the data in the packet... */
		memcpy(buf, interface->rbuf + interface->rbuf_offset,
		    hdr.bh_caplen);
		interface->rbuf_offset += hdr.bh_caplen;
		return (hdr.bh_caplen);
	} while (!length);
	return (0);
}


Generated by: GCOVR (Version 3.3)

Line	Branch	Exec	Source
1			/* $OpenBSD: bpf.c,v 1.2 2017/04/19 05:36:13 natano Exp $ */
2
3			/* BPF socket interface code, originally contributed by Archie Cobbs. */
4
5			/*
6			* Copyright (c) 1995, 1996, 1998, 1999
7			* The Internet Software Consortium. All rights reserved.
8			*
9			* Redistribution and use in source and binary forms, with or without
10			* modification, are permitted provided that the following conditions
11			* are met:
12			*
13			* 1. Redistributions of source code must retain the above copyright
14			* notice, this list of conditions and the following disclaimer.
15			* 2. Redistributions in binary form must reproduce the above copyright
16			* notice, this list of conditions and the following disclaimer in the
17			* documentation and/or other materials provided with the distribution.
18			* 3. Neither the name of The Internet Software Consortium nor the names
19			* of its contributors may be used to endorse or promote products derived
20			* from this software without specific prior written permission.
21			*
22			* THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
23			* CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
24			* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
25			* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
26			* DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
27			* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28			* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
29			* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
30			* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
31			* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
32			* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
33			* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34			* SUCH DAMAGE.
35			*
36			* This software has been written for the Internet Software Consortium
37			* by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
38			* Enterprises. To learn more about the Internet Software Consortium,
39			* see ``http://www.vix.com/isc''. To learn more about Vixie
40			* Enterprises, see ``http://www.vix.com''.
41			*/
42
43			#include <sys/types.h>
44			#include <sys/ioctl.h>
45			#include <sys/socket.h>
46
47			#include <net/bpf.h>
48			#include <net/if.h>
49
50			#include <netinet/in.h>
51			#include <netinet/if_ether.h>
52
53			#include <errno.h>
54			#include <fcntl.h>
55			#include <stdio.h>
56			#include <stdlib.h>
57			#include <string.h>
58			#include <unistd.h>
59
60			#include "dhcp.h"
61			#include "dhcpd.h"
62			#include "log.h"
63
64			ssize_t send_packet_layer3(struct interface_info *,
65			void , size_t, struct packet_ctx );
66
67			/*
68			* Called by get_interface_list for each interface that's discovered.
69			* Opens a packet filter for each interface and adds it to the select
70			* mask.
71			*/
72			int
73			if_register_bpf(struct interface_info *info)
74			{
75			int sock;
76
77			/* Open the BPF device */
78			if ((sock = open("/dev/bpf", O_RDWR)) == -1)
79			fatal("Can't open bpf device");
80
81			/* Set the BPF device to point at this interface. */
82			if (ioctl(sock, BIOCSETIF, &info->ifr) == -1)
83			fatal("Can't attach interface %s to bpf device", info->name);
84
85			return (sock);
86			}
87
88			void
89			if_register_send(struct interface_info *info)
90			{
91			/*
92			* If we're using the bpf API for sending and receiving, we
93			* don't need to register this interface twice.
94			*/
95			info->wfdesc = info->rfdesc;
96			}
97
98			/* DHCPv6 BPF filters. */
99
100			/*
101			* Packet filter program: 'ip6 and udp and dst port DHCP6_SERVER_PORT'
102			*/
103			struct bpf_insn dhcp6_bpf_sfilter[] = {
104			/* Make sure this is an IP packet... */
105			BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12),
106			BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IPV6, 0, 5),
107
108			/* Make sure this is an UDP packet. */
109			BPF_STMT(BPF_LD + BPF_B + BPF_ABS, 20),
110			BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 0, 3),
111
112			/* Make sure it is the right port. */
113			BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 56),
114			BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DHCP6_SERVER_PORT, 0, 1),
115
116			/* If we passed all the tests, ask for the whole packet. */
117			BPF_STMT(BPF_RET + BPF_K, (u_int)-1),
118
119			/* Otherwise, drop it. */
120			BPF_STMT(BPF_RET + BPF_K, 0),
121			};
122
123			int dhcp6_bpf_sfilter_len = sizeof(dhcp6_bpf_sfilter) / sizeof(struct bpf_insn);
124
125			/*
126			* Packet filter program: 'ip6 and udp'
127			*/
128			struct bpf_insn dhcp6_bpf_wfilter[] = {
129			/* Make sure this is an IP packet... */
130			BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12),
131			BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IPV6, 0, 3),
132
133			/* Make sure this is an UDP packet. */
134			BPF_STMT(BPF_LD + BPF_B + BPF_ABS, 20),
135			BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 0, 1),
136
137			/* If we passed all the tests, ask for the whole packet. */
138			BPF_STMT(BPF_RET + BPF_K, (u_int)-1),
139
140			/* Otherwise, drop it. */
141			BPF_STMT(BPF_RET + BPF_K, 0),
142			};
143
144			int dhcp6_bpf_wfilter_len = sizeof(dhcp6_bpf_wfilter) / sizeof(struct bpf_insn);
145
146
147			void
148			if_register_receive(struct interface_info *info)
149			{
150			struct bpf_version v;
151			struct bpf_program p;
152			int flag = 1, sz, cmplt = 0;
153
154			/* Open a BPF device and hang it on this interface... */
155			info->rfdesc = if_register_bpf(info);
156
157			/* Make sure the BPF version is in range... */
158			if (ioctl(info->rfdesc, BIOCVERSION, &v) == -1)
159			fatal("Can't get BPF version");
160
161			if (v.bv_major != BPF_MAJOR_VERSION \|\|
162			v.bv_minor < BPF_MINOR_VERSION)
163			fatalx("Kernel BPF version out of range - recompile dhcpd!");
164
165			/*
166			* Set immediate mode so that reads return as soon as a packet
167			* comes in, rather than waiting for the input buffer to fill
168			* with packets.
169			*/
170			if (ioctl(info->rfdesc, BIOCIMMEDIATE, &flag) == -1)
171			fatal("Can't set immediate mode on bpf device");
172
173			/* make sure kernel fills in the source ethernet address */
174			if (ioctl(info->rfdesc, BIOCSHDRCMPLT, &cmplt) == -1)
175			fatal("Can't set header complete flag on bpf device");
176
177			/* Get the required BPF buffer length from the kernel. */
178			if (ioctl(info->rfdesc, BIOCGBLEN, &sz) == -1)
179			fatal("Can't get bpf buffer length");
180			info->rbuf_max = sz;
181			info->rbuf = malloc(info->rbuf_max);
182			if (!info->rbuf)
183			fatalx("Can't allocate %lu bytes for bpf input buffer.",
184			(unsigned long)info->rbuf_max);
185			info->rbuf_offset = 0;
186			info->rbuf_len = 0;
187
188			/* Set up the bpf filter program structure. */
189			p.bf_len = dhcp6_bpf_sfilter_len;
190			p.bf_insns = dhcp6_bpf_sfilter;
191			if (ioctl(info->rfdesc, BIOCSETF, &p) == -1)
192			fatal("Can't install packet filter program");
193
194			/* Set up the bpf write filter program structure. */
195			p.bf_len = dhcp6_bpf_wfilter_len;
196			p.bf_insns = dhcp6_bpf_wfilter;
197			if (ioctl(info->rfdesc, BIOCSETWF, &p) == -1)
198			fatal("Can't install write filter program");
199
200			/* Only get input packets. */
201			flag = BPF_DIRECTION_OUT;
202			if (ioctl(info->rfdesc, BIOCSDIRFILT , &flag) == -1)
203			fatal("Can't set BPF direction capture");
204
205			/* Drop them so they don't go up in the network stack. */
206			flag = 1;
207			if (ioctl(info->rfdesc, BIOCSFILDROP, &flag) == -1)
208			fatal("Can't set BPF filter drop");
209
210			/* make sure these settings cannot be changed after dropping privs */
211			if (ioctl(info->rfdesc, BIOCLOCK) == -1)
212			fatal("Failed to lock bpf descriptor");
213			}
214
215			ssize_t
216			send_packet_layer3(struct interface_info intf, void raw, size_t len,
217			struct packet_ctx *pc)
218			{
219			struct cmsghdr *cmsg;
220			ssize_t sendlen;
221			struct msghdr msg;
222			struct in6_pktinfo *ipi6;
223			struct sockaddr_storage ss;
224			struct iovec iov[2];
225			uint8_t cmsgbuf[
226			CMSG_SPACE(sizeof(struct in6_pktinfo))
227			];
228
229			log_debug(" sending %ld bytes to %s:%d via %s",
230			len, v6addr2str(&ss2sin6(&pc->pc_dst)->sin6_addr),
231			ntohs(ss2sin6(&pc->pc_dst)->sin6_port), intf->name);
232
233			memset(&msg, 0, sizeof(msg));
234			iov[0].iov_base = raw;
235			iov[0].iov_len = len;
236			msg.msg_iov = iov;
237			msg.msg_iovlen = 1;
238
239			ss = pc->pc_dst;
240			ss2sin6(&ss)->sin6_scope_id = intf->index;
241			msg.msg_name = &ss;
242			msg.msg_namelen = ss.ss_len;
243
244			/* If binded to multicast we should select an interface. */
245			if (IN6_IS_ADDR_MULTICAST(&ss2sin6(&ss)->sin6_addr)) {
246			memset(cmsgbuf, 0, sizeof(cmsgbuf));
247			msg.msg_control = cmsgbuf;
248			msg.msg_controllen = sizeof(cmsgbuf);
249
250			/* Use the IPV6_PKTINFO to select the interface. */
251			cmsg = (struct cmsghdr *)CMSG_FIRSTHDR(&msg);
252			cmsg->cmsg_len = CMSG_LEN(sizeof(*ipi6));
253			cmsg->cmsg_level = IPPROTO_IPV6;
254			cmsg->cmsg_type = IPV6_PKTINFO;
255
256			ipi6 = (struct in6_pktinfo *)CMSG_DATA(cmsg);
257			ipi6->ipi6_ifindex = intf->index;
258			}
259
260			if ((sendlen = sendmsg(pc->pc_sd, &msg, 0)) == -1) {
261			log_warn(" failed to send message");
262			return -1;
263			}
264			if (sendlen < (ssize_t)len)
265			log_warnx(" sent less bytes than expected (%ld < %ld)",
266			sendlen, len);
267
268			return sendlen;
269			}
270
271			ssize_t
272			send_packet(struct interface_info *interface,
273			void raw, size_t len, struct packet_ctx pc)
274			{
275			unsigned char buf[256];
276			struct iovec iov[2];
277			int result, bufp = 0;
278
279			if (pc->pc_sd != 0)
280			return send_packet_layer3(interface, raw, len, pc);
281
282			/* Assemble the headers... */
283			assemble_hw_header(buf, &bufp, pc);
284			assemble_udp_ip6_header(buf, &bufp, pc, raw, len);
285
286			/* Fire it off */
287			iov[0].iov_base = (char *)buf;
288			iov[0].iov_len = bufp;
289			iov[1].iov_base = (char *)raw;
290			iov[1].iov_len = len;
291
292			result = writev(interface->wfdesc, iov, 2);
293			if (result == -1)
294			log_warn("send_packet");
295
296			return (result);
297			}
298
299			ssize_t
300			receive_packet(struct interface_info interface, unsigned char buf,
301			size_t len, struct packet_ctx *pc)
302			{
303			int length = 0, offset = 0;
304			struct bpf_hdr hdr;
305
306			/*
307			* All this complexity is because BPF doesn't guarantee that
308			* only one packet will be returned at a time. We're getting
309			* what we deserve, though - this is a terrible abuse of the BPF
310			* interface. Sigh.
311			*/
312
313			/* Process packets until we get one we can return or until we've
314			* done a read and gotten nothing we can return...
315			*/
316			do {
317			/* If the buffer is empty, fill it. */
318			if (interface->rbuf_offset == interface->rbuf_len) {
319			length = read(interface->rfdesc, interface->rbuf,
320			interface->rbuf_max);
321			if (length <= 0)
322			return (length);
323			interface->rbuf_offset = 0;
324			interface->rbuf_len = length;
325			}
326
327			/*
328			* If there isn't room for a whole bpf header, something
329			* went wrong, but we'll ignore it and hope it goes
330			* away... XXX
331			*/
332			if (interface->rbuf_len - interface->rbuf_offset <
333			sizeof(hdr)) {
334			interface->rbuf_offset = interface->rbuf_len;
335			continue;
336			}
337
338			/* Copy out a bpf header... */
339			memcpy(&hdr, &interface->rbuf[interface->rbuf_offset],
340			sizeof(hdr));
341
342			/*
343			* If the bpf header plus data doesn't fit in what's
344			* left of the buffer, stick head in sand yet again...
345			*/
346			if (interface->rbuf_offset + hdr.bh_hdrlen + hdr.bh_caplen >
347			interface->rbuf_len) {
348			interface->rbuf_offset = interface->rbuf_len;
349			continue;
350			}
351
352			/*
353			* If the captured data wasn't the whole packet, or if
354			* the packet won't fit in the input buffer, all we can
355			* do is drop it.
356			*/
357			if (hdr.bh_caplen != hdr.bh_datalen) {
358			interface->rbuf_offset += hdr.bh_hdrlen =
359			hdr.bh_caplen;
360			continue;
361			}
362
363			/* Skip over the BPF header... */
364			interface->rbuf_offset += hdr.bh_hdrlen;
365
366			/* Decode the physical header... */
367			offset = decode_hw_header(interface->rbuf,
368			interface->rbuf_offset, pc);
369
370			/*
371			* If a physical layer checksum failed (dunno of any
372			* physical layer that supports this, but WTH), skip
373			* this packet.
374			*/
375			if (offset < 0) {
376			interface->rbuf_offset += hdr.bh_caplen;
377			continue;
378			}
379			interface->rbuf_offset += offset;
380			hdr.bh_caplen -= offset;
381
382			/* Decode the IP and UDP headers... */
383			offset = decode_udp_ip6_header(interface->rbuf,
384			interface->rbuf_offset, pc, hdr.bh_caplen);
385
386			/* If the IP or UDP checksum was bad, skip the packet... */
387			if (offset < 0) {
388			interface->rbuf_offset += hdr.bh_caplen;
389			continue;
390			}
391			interface->rbuf_offset += offset;
392			hdr.bh_caplen -= offset;
393
394			/*
395			* If there's not enough room to stash the packet data,
396			* we have to skip it (this shouldn't happen in real
397			* life, though).
398			*/
399			if (hdr.bh_caplen > len) {
400			interface->rbuf_offset += hdr.bh_caplen;
401			continue;
402			}
403
404			/* Copy out the data in the packet... */
405			memcpy(buf, interface->rbuf + interface->rbuf_offset,
406			hdr.bh_caplen);
407			interface->rbuf_offset += hdr.bh_caplen;
408			return (hdr.bh_caplen);
409			} while (!length);
410			return (0);
411			}