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/* lpf.c
Linux packet filter code, contributed by Brian Murrel at Interlinx
Support Services in Vancouver, B.C. */
/*
* Copyright (c) 1995, 1996, 1998 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: lpf.c,v 1.1 1998/12/22 22:34:54 mellon Exp $ Copyright (c) 1995, 1996, 1998 The Internet Software Consortium. All rights reserved.\n";
#endif /* not lint */
#include "dhcpd.h"
#if defined (USE_LPF_SEND) || defined (USE_LPF_RECEIVE)
#include <sys/ioctl.h>
#include <sys/uio.h>
#include <net/bpf.h>
#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_LPF_SEND
void if_reinitialize_send (info)
struct interface_info *info;
{
}
#endif
#ifdef USE_LPF_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_lpf (info)
struct interface_info *info;
{
int sock;
char filename[50];
int b;
struct sockaddr sa;
/* Make an LPF socket. */
if ((sock = socket(PF_INET, SOCK_PACKET, htons(ETH_P_ALL))) < 0)
error("Open a socket for LPF: %m");
/* Bind to the interface name */
memset (&sa, 0, sizeof sa);
sa.sa_family = AF_INET;
strncpy (sa.sa_data, (const char *)info -> ifp, sizeof sa.sa_data);
if (bind (sock, &sa, sizeof sa))
error("Bind socket to interface: %m");
return sock;
}
#endif /* USE_LPF_SEND || USE_LPF_RECEIVE */
#ifdef USE_LPF_SEND
void if_register_send (info)
struct interface_info *info;
{
/* If we're using the lpf API for sending and receiving,
we don't need to register this interface twice. */
#ifndef USE_LPF_RECEIVE
info -> wfdesc = if_register_lpf (info, interface);
#else
info -> wfdesc = info -> rfdesc;
#endif
if (!quiet_interface_discovery)
note ("Sending on LPF/%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_LPF_SEND */
#ifdef USE_LPF_RECEIVE
/* Defined in bpf.c. We can't extern these in dhcpd.h without pulling
in bpf includes... */
extern struct bpf_insn dhcp_bpf_filter [];
extern int dhcp_bpf_filter_len;
void if_register_receive (info)
struct interface_info *info;
{
/* Open a LPF device and hang it on this interface... */
info -> rfdesc = if_register_lpf (info);
/* Set up the bpf filter program structure. This is defined in
bpf.c */
p.bf_len = dhcp_bpf_filter_len;
p.bf_insns = dhcp_bpf_filter;
/* Patch the server port into the LPF 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 (setsockopt (info -> rfdesc, SOL_SOCKET, SO_ATTACH_FILTER, &p,
sizeof p) < 0)
error ("Can't install packet filter program: %m");
if (!quiet_interface_discovery)
note ("Listening on LPF/%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_LPF_RECEIVE */
#ifdef USE_LPF_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 [1500];
if (!strcmp (interface -> name, "fallback"))
return send_fallback (interface, packet, raw,
len, from, to, hto);
/* 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);
memcpy (buf + bufp, raw, len);
return send (interface -> wfdesc, buf, bufp + len, 0);
}
#endif /* USE_LPF_SEND */
#ifdef USE_LPF_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 nread;
int length = 0;
int offset = 0;
unsigned char ibuf [1500 + sizeof (struct enstamp)];
int bufix = 0;
length = read (interface -> rfdesc, ibuf, sizeof ibuf);
if (length <= 0)
return length;
bufix = sizeof (struct enstamp);
/* Decode the physical header... */
offset = decode_hw_header (interface, ibuf, bufix, hfrom);
/* If a physical layer checksum failed (dunno of any
physical layer that supports this, but WTH), skip this
packet. */
if (offset < 0) {
return 0;
}
bufix += offset;
length -= offset;
/* Decode the IP and UDP headers... */
offset = decode_udp_ip_header (interface, ibuf, bufix,
from, (unsigned char *)0, length);
/* If the IP or UDP checksum was bad, skip the packet... */
if (offset < 0)
return 0;
bufix += offset;
length -= offset;
/* Copy out the data in the packet... */
memcpy (buf, &ibuf [bufix], length);
return length;
}
int can_unicast_without_arp ()
{
return 1;
}
void maybe_setup_fallback ()
{
struct interface_info *fbi;
fbi = setup_fallback ();
if (fbi) {
if_register_fallback (fbi);
add_protocol ("fallback", fallback_interface -> wfdesc,
fallback_discard, fallback_interface);
}
}
#endif
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