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/* bpf.c
BPF socket interface code, originally contributed by Archie Cobbs. */
/*
* Copyright (c) 1995, 1996 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''.
*/
#ifndef lint
static char copyright[] =
"$Id: bpf.c,v 1.18 1997/06/08 03:18:07 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium. All rights reserved.\n";
#endif /* not lint */
#include "dhcpd.h"
#if defined (USE_BPF_SEND) || defined (USE_BPF_RECEIVE)
#include <sys/ioctl.h>
#include <sys/uio.h>
#include <net/bpf.h>
#ifdef NEED_OSF_PFILT_HACKS
#include <net/pfilt.h>
#endif
#include <netinet/in_systm.h>
#include "includes/netinet/ip.h"
#include "includes/netinet/udp.h"
#include "includes/netinet/if_ether.h"
/* Reinitializes the specified interface after an address change. This
is not required for packet-filter APIs. */
#ifdef USE_BPF_SEND
void if_reinitialize_send (info)
struct interface_info *info;
{
}
#endif
#ifdef USE_BPF_RECEIVE
void if_reinitialize_receive (info)
struct interface_info *info;
{
}
#endif
/* 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 (info)
struct interface_info *info;
{
int sock;
char filename[50];
int b;
/* Open a BPF device */
for (b = 0; 1; b++) {
#ifndef NO_SNPRINTF
snprintf(filename, sizeof(filename), BPF_FORMAT, b);
#else
sprintf(filename, BPF_FORMAT, b);
#endif
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, info -> ifp) < 0)
error ("Can't attach interface %s to bpf device %s: %m",
info -> name, filename);
return sock;
}
#endif /* USE_BPF_SEND || USE_BPF_RECEIVE */
#ifdef USE_BPF_SEND
void if_register_send (info)
struct interface_info *info;
{
/* If we're using the bpf API for sending and receiving,
we don't need to register this interface twice. */
#ifndef USE_BPF_RECEIVE
info -> wfdesc = if_register_bpf (info, interface);
#else
info -> wfdesc = info -> rfdesc;
#endif
note ("Sending on BPF/%s/%s/%s",
info -> name,
print_hw_addr (info -> hw_address.htype,
info -> hw_address.hlen,
info -> hw_address.haddr),
(info -> shared_network ?
info -> shared_network -> name : "unattached"));
}
#endif /* USE_BPF_SEND */
#ifdef USE_BPF_RECEIVE
/* 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! XXX */
struct bpf_insn 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),
};
void if_register_receive (info)
struct interface_info *info;
{
int flag = 1;
struct bpf_version v;
u_int32_t addr;
struct bpf_program p;
u_int32_t bits;
/* 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) < 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 (info -> rfdesc, BIOCIMMEDIATE, &flag) < 0)
error ("Can't set immediate mode on bpf device: %m");
#ifdef NEED_OSF_PFILT_HACKS
/* Allow the copyall flag to be set... */
if (ioctl(info -> rfdesc, EIOCALLOWCOPYALL, &flag) < 0)
error ("Can't set ALLOWCOPYALL: %m");
/* Clear all the packet filter mode bits first... */
bits = 0;
if (ioctl (info -> rfdesc, EIOCMBIS, &bits) < 0)
error ("Can't clear pfilt bits: %m");
/* Set the ENBATCH, ENCOPYALL, ENBPFHDR bits... */
bits = ENBATCH | ENCOPYALL | ENBPFHDR;
if (ioctl (info -> rfdesc, EIOCMBIS, &bits) < 0)
error ("Can't set ENBATCH|ENCOPYALL|ENBPFHDR: %m");
#endif
/* Get the required BPF buffer length from the kernel. */
if (ioctl (info -> rfdesc, BIOCGBLEN, &info -> rbuf_max) < 0)
error ("Can't get bpf buffer length: %m");
info -> rbuf = malloc (info -> rbuf_max);
if (!info -> rbuf)
error ("Can't allocate %d bytes for bpf input buffer.");
info -> rbuf_offset = 0;
info -> rbuf_len = 0;
/* Set up the bpf filter program structure. */
p.bf_len = sizeof filter / sizeof (struct bpf_insn);
p.bf_insns = filter;
/* Patch the server port into the BPF program...
XXX changes to filter program may require changes
to the insn number(s) used below! XXX */
filter [8].k = ntohs (local_port);
if (ioctl (info -> rfdesc, BIOCSETF, &p) < 0)
error ("Can't install packet filter program: %m");
note ("Listening on BPF/%s/%s/%s",
info -> name,
print_hw_addr (info -> hw_address.htype,
info -> hw_address.hlen,
info -> hw_address.haddr),
(info -> shared_network ?
info -> shared_network -> name : "unattached"));
}
#endif /* USE_BPF_RECEIVE */
#ifdef USE_BPF_SEND
ssize_t send_packet (interface, packet, raw, len, from, to, hto)
struct interface_info *interface;
struct packet *packet;
struct dhcp_packet *raw;
size_t len;
struct in_addr from;
struct sockaddr_in *to;
struct hardware *hto;
{
int bufp = 0;
unsigned char buf [256];
struct iovec iov [2];
/* Assemble the headers... */
assemble_hw_header (interface, buf, &bufp, hto);
assemble_udp_ip_header (interface, buf, &bufp, from.s_addr,
to -> sin_addr.s_addr, to -> sin_port,
(unsigned char *)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;
return writev(interface -> wfdesc, iov, 2);
}
#endif /* USE_BPF_SEND */
#ifdef USE_BPF_RECEIVE
ssize_t receive_packet (interface, buf, len, from, hfrom)
struct interface_info *interface;
unsigned char *buf;
size_t len;
struct sockaddr_in *from;
struct hardware *hfrom;
{
int length = 0;
int 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,
interface -> rbuf,
interface -> 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) {
interface -> rbuf_offset += hdr.bh_caplen;
continue;
}
interface -> rbuf_offset += offset;
hdr.bh_caplen -= offset;
/* Decode the IP and UDP headers... */
offset = decode_udp_ip_header (interface,
interface -> rbuf,
interface -> rbuf_offset,
from,
(unsigned char *)0,
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;
}
#endif
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