/* bpf.c
BPF socket interface code, originally contributed by Archie Cobbs. */
/*
* Copyright (c) 2004,2007,2009 by Internet Systems Consortium, Inc. ("ISC")
* Copyright (c) 1996-2003 by Internet Software Consortium
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
* OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* Internet Systems Consortium, Inc.
* 950 Charter Street
* Redwood City, CA 94063
* <info@isc.org>
* https://www.isc.org/
*
* This software was contributed to Internet Systems Consortium
* by Archie Cobbs.
*
* Patches for FDDI support on Digital Unix were written by Bill
* Stapleton, and maintained for a while by Mike Meredith before he
* managed to get me to integrate them.
*/
#include "dhcpd.h"
#if defined (USE_BPF_SEND) || defined (USE_BPF_RECEIVE) \
|| defined (USE_LPF_RECEIVE)
# if defined (USE_LPF_RECEIVE)
# include <asm/types.h>
# include <linux/filter.h>
# define bpf_insn sock_filter /* Linux: dare to be gratuitously different. */
# else
# include <sys/ioctl.h>
# include <sys/uio.h>
# include <net/bpf.h>
# include <net/if_types.h>
# if defined (NEED_OSF_PFILT_HACKS)
# include <net/pfilt.h>
# endif
# endif
#include <netinet/in_systm.h>
#include "includes/netinet/ip.h"
#include "includes/netinet/udp.h"
#include "includes/netinet/if_ether.h"
#endif
#ifdef USE_BPF_RECEIVE
#include <ifaddrs.h>
#endif
#include <errno.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. */
#if defined (USE_BPF_SEND) || defined (USE_BPF_RECEIVE)
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++) {
/* %Audit% 31 bytes max. %2004.06.17,Safe% */
sprintf(filename, BPF_FORMAT, b);
sock = open (filename, O_RDWR, 0);
if (sock < 0) {
if (errno == EBUSY) {
continue;
} else {
if (!b)
log_fatal ("No bpf devices.%s%s%s",
" Please read the README",
" section for your operating",
" system.");
log_fatal ("Can't find free bpf: %m");
}
} else {
break;
}
}
/* Set the BPF device to point at this interface. */
if (ioctl (sock, BIOCSETIF, info -> ifp) < 0)
log_fatal ("Can't attach interface %s to bpf device %s: %m",
info -> name, filename);
get_hw_addr(info->name, &info->hw_address);
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
if (!quiet_interface_discovery)
log_info ("Sending on BPF/%s/%s%s%s",
info -> name,
print_hw_addr (info -> hw_address.hbuf [0],
info -> hw_address.hlen - 1,
&info -> hw_address.hbuf [1]),
(info -> shared_network ? "/" : ""),
(info -> shared_network ?
info -> shared_network -> name : ""));
}
void if_deregister_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
close (info -> wfdesc);
#endif
info -> wfdesc = -1;
if (!quiet_interface_discovery)
log_info ("Disabling output on BPF/%s/%s%s%s",
info -> name,
print_hw_addr (info -> hw_address.hbuf [0],
info -> hw_address.hlen - 1,
&info -> hw_address.hbuf [1]),
(info -> shared_network ? "/" : ""),
(info -> shared_network ?
info -> shared_network -> name : ""));
}
#endif /* USE_BPF_SEND */
#if defined (USE_BPF_RECEIVE) || defined (USE_LPF_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 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),
};
#if defined (DEC_FDDI)
struct bpf_insn *bpf_fddi_filter;
#endif
int dhcp_bpf_filter_len = sizeof dhcp_bpf_filter / sizeof (struct bpf_insn);
#if defined (HAVE_TR_SUPPORT)
struct bpf_insn dhcp_bpf_tr_filter [] = {
/* accept all token ring packets due to variable length header */
/* if we want to get clever, insert the program here */
/* 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_tr_filter_len = (sizeof dhcp_bpf_tr_filter /
sizeof (struct bpf_insn));
#endif /* HAVE_TR_SUPPORT */
#endif /* USE_LPF_RECEIVE || USE_BPF_RECEIVE */
#if defined (USE_BPF_RECEIVE)
void if_register_receive (info)
struct interface_info *info;
{
int flag = 1;
struct bpf_version v;
struct bpf_program p;
#ifdef NEED_OSF_PFILT_HACKS
u_int32_t bits;
#endif
#ifdef DEC_FDDI
int link_layer;
#endif /* DEC_FDDI */
/* 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)
log_fatal ("Can't get BPF version: %m");
if (v.bv_major != BPF_MAJOR_VERSION ||
v.bv_minor < BPF_MINOR_VERSION)
log_fatal ("BPF version mismatch - recompile DHCP!");
/* 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)
log_fatal ("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)
log_fatal ("Can't set ALLOWCOPYALL: %m");
/* Clear all the packet filter mode bits first... */
bits = 0;
if (ioctl (info -> rfdesc, EIOCMBIS, &bits) < 0)
log_fatal ("Can't clear pfilt bits: %m");
/* Set the ENBATCH, ENCOPYALL, ENBPFHDR bits... */
bits = ENBATCH | ENCOPYALL | ENBPFHDR;
if (ioctl (info -> rfdesc, EIOCMBIS, &bits) < 0)
log_fatal ("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)
log_fatal ("Can't get bpf buffer length: %m");
info -> rbuf = dmalloc (info -> rbuf_max, MDL);
if (!info -> rbuf)
log_fatal ("Can't allocate %ld bytes for bpf input buffer.",
(long)(info -> rbuf_max));
info -> rbuf_offset = 0;
info -> rbuf_len = 0;
/* Set up the bpf filter program structure. */
p.bf_len = dhcp_bpf_filter_len;
#ifdef DEC_FDDI
/* See if this is an FDDI interface, flag it for later. */
if (ioctl(info -> rfdesc, BIOCGDLT, &link_layer) >= 0 &&
link_layer == DLT_FDDI) {
if (!bpf_fddi_filter) {
bpf_fddi_filter = dmalloc (sizeof bpf_fddi_filter,
MDL);
if (!bpf_fddi_filter)
log_fatal ("No memory for FDDI filter.");
memcpy (bpf_fddi_filter,
dhcp_bpf_filter, sizeof dhcp_bpf_filter);
/* Patch the BPF program to account for the difference
in length between ethernet headers (14), FDDI and
802.2 headers (16 +8=24, +10).
XXX changes to filter program may require changes to
XXX the insn number(s) used below! */
bpf_fddi_filter[0].k += 10;
bpf_fddi_filter[2].k += 10;
bpf_fddi_filter[4].k += 10;
bpf_fddi_filter[6].k += 10;
bpf_fddi_filter[7].k += 10;
}
p.bf_insns = bpf_fddi_filter;
} else
#endif /* DEC_FDDI */
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! XXX */
dhcp_bpf_filter [8].k = ntohs (local_port);
if (ioctl (info -> rfdesc, BIOCSETF, &p) < 0)
log_fatal ("Can't install packet filter program: %m");
if (!quiet_interface_discovery)
log_info ("Listening on BPF/%s/%s%s%s",
info -> name,
print_hw_addr (info -> hw_address.hbuf [0],
info -> hw_address.hlen - 1,
&info -> hw_address.hbuf [1]),
(info -> shared_network ? "/" : ""),
(info -> shared_network ?
info -> shared_network -> name : ""));
}
void if_deregister_receive (info)
struct interface_info *info;
{
close (info -> rfdesc);
info -> rfdesc = -1;
if (!quiet_interface_discovery)
log_info ("Disabling input on BPF/%s/%s%s%s",
info -> name,
print_hw_addr (info -> hw_address.hbuf [0],
info -> hw_address.hlen - 1,
&info -> hw_address.hbuf [1]),
(info -> shared_network ? "/" : ""),
(info -> shared_network ?
info -> shared_network -> name : ""));
}
#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;
{
unsigned hbufp = 0, ibufp = 0;
double hw [4];
double ip [32];
struct iovec iov [3];
int result;
if (!strcmp (interface -> name, "fallback"))
return send_fallback (interface, packet, raw,
len, from, to, hto);
/* Assemble the headers... */
assemble_hw_header (interface, (unsigned char *)hw, &hbufp, hto);
assemble_udp_ip_header (interface,
(unsigned char *)ip, &ibufp, from.s_addr,
to -> sin_addr.s_addr, to -> sin_port,
(unsigned char *)raw, len);
/* Fire it off */
iov [0].iov_base = ((char *)hw);
iov [0].iov_len = hbufp;
iov [1].iov_base = ((char *)ip);
iov [1].iov_len = ibufp;
iov [2].iov_base = (char *)raw;
iov [2].iov_len = len;
result = writev(interface -> wfdesc, iov, 3);
if (result < 0)
log_error ("send_packet: %m");
return result;
}
#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;
unsigned paylen;
/* 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,
(size_t)interface -> rbuf_max);
if (length <= 0) {
#ifdef __FreeBSD__
if (errno == ENXIO) {
#else
if (errno == EIO) {
#endif
dhcp_interface_remove
((omapi_object_t *)interface,
(omapi_object_t *)0);
}
return length;
}
interface -> rbuf_offset = 0;
interface -> 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 (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 =
BPF_WORDALIGN (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 =
BPF_WORDALIGN (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, hdr.bh_caplen, &paylen);
/* If the IP or UDP checksum was bad, skip the packet... */
if (offset < 0) {
interface -> rbuf_offset =
BPF_WORDALIGN (interface -> rbuf_offset +
hdr.bh_caplen);
continue;
}
interface -> rbuf_offset = 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 =
BPF_WORDALIGN (interface -> rbuf_offset +
hdr.bh_caplen);
continue;
}
/* Copy out the data in the packet... */
memcpy(buf, interface->rbuf + interface->rbuf_offset, paylen);
interface -> rbuf_offset =
BPF_WORDALIGN (interface -> rbuf_offset +
hdr.bh_caplen);
return paylen;
} while (!length);
return 0;
}
int can_unicast_without_arp (ip)
struct interface_info *ip;
{
return 1;
}
int can_receive_unicast_unconfigured (ip)
struct interface_info *ip;
{
return 1;
}
int supports_multiple_interfaces (ip)
struct interface_info *ip;
{
return 1;
}
void maybe_setup_fallback ()
{
isc_result_t status;
struct interface_info *fbi = (struct interface_info *)0;
if (setup_fallback (&fbi, MDL)) {
if_register_fallback (fbi);
status = omapi_register_io_object ((omapi_object_t *)fbi,
if_readsocket, 0,
fallback_discard, 0, 0);
if (status != ISC_R_SUCCESS)
log_fatal ("Can't register I/O handle for %s: %s",
fbi -> name, isc_result_totext (status));
interface_dereference (&fbi, MDL);
}
}
void
get_hw_addr(const char *name, struct hardware *hw) {
struct ifaddrs *ifa;
struct ifaddrs *p;
struct sockaddr_dl *sa;
if (getifaddrs(&ifa) != 0) {
log_fatal("Error getting interface information; %m");
}
/*
* Loop through our interfaces finding a match.
*/
sa = NULL;
for (p=ifa; (p != NULL) && (sa == NULL); p = p->ifa_next) {
if ((p->ifa_addr->sa_family == AF_LINK) &&
!strcmp(p->ifa_name, name)) {
sa = (struct sockaddr_dl *)p->ifa_addr;
}
}
if (sa == NULL) {
log_fatal("No interface called '%s'", name);
}
/*
* Pull out the appropriate information.
*/
switch (sa->sdl_type) {
case IFT_ETHER:
hw->hlen = sa->sdl_alen + 1;
hw->hbuf[0] = HTYPE_ETHER;
memcpy(&hw->hbuf[1], LLADDR(sa), sa->sdl_alen);
break;
case IFT_ISO88023:
case IFT_ISO88024: /* "token ring" */
case IFT_ISO88025:
case IFT_ISO88026:
hw->hlen = sa->sdl_alen + 1;
hw->hbuf[0] = HTYPE_IEEE802;
memcpy(&hw->hbuf[1], LLADDR(sa), sa->sdl_alen);
break;
#ifdef IFT_FDDI
case IFT_FDDI:
hw->hlen = sa->sdl_alen + 1;
hw->hbuf[0] = HTYPE_FDDI;
memcpy(&hw->hbuf[1], LLADDR(sa), sa->sdl_alen);
break;
#endif /* IFT_FDDI */
default:
log_fatal("Unsupported device type %d for \"%s\"",
sa->sdl_type, name);
}
freeifaddrs(ifa);
}
#endif
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