288 lines
8.6 KiB
C
288 lines
8.6 KiB
C
/* lpf.c
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Linux packet filter code, contributed by Brian Murrel at Interlinx
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Support Services in Vancouver, B.C. */
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/*
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* Copyright (c) 1995, 1996, 1998, 1999
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* The Internet Software Consortium. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of The Internet Software Consortium nor the names
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* of its contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
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* CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This software has been written for the Internet Software Consortium
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* by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
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* Enterprises. To learn more about the Internet Software Consortium,
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* see ``http://www.vix.com/isc''. To learn more about Vixie
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* Enterprises, see ``http://www.vix.com''.
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*/
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#ifndef lint
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static char copyright[] =
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"$Id: lpf.c,v 1.1.2.4 1999/02/09 04:51:05 mellon Exp $ Copyright (c) 1995, 1996, 1998, 1999 The Internet Software Consortium. All rights reserved.\n";
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#endif /* not lint */
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#include "dhcpd.h"
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#if defined (USE_LPF_SEND) || defined (USE_LPF_RECEIVE)
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#include <sys/ioctl.h>
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#include <sys/uio.h>
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#include <asm/types.h>
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#include <linux/filter.h>
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#include <linux/if_ether.h>
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#include <netinet/in_systm.h>
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#include "includes/netinet/ip.h"
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#include "includes/netinet/udp.h"
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#include "includes/netinet/if_ether.h"
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/* Reinitializes the specified interface after an address change. This
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is not required for packet-filter APIs. */
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#ifdef USE_LPF_SEND
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void if_reinitialize_send (info)
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struct interface_info *info;
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{
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}
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#endif
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#ifdef USE_LPF_RECEIVE
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void if_reinitialize_receive (info)
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struct interface_info *info;
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{
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}
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#endif
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/* Called by get_interface_list for each interface that's discovered.
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Opens a packet filter for each interface and adds it to the select
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mask. */
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int if_register_lpf (info)
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struct interface_info *info;
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{
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int sock;
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char filename[50];
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int b;
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struct sockaddr sa;
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/* Make an LPF socket. */
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if ((sock = socket(PF_PACKET, SOCK_PACKET, htons(ETH_P_ALL))) < 0) {
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if (errno == ENOPROTOOPT || errno == EPROTONOSUPPORT ||
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errno == ESOCKTNOSUPPORT || errno == EPFNOSUPPORT ||
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errno == EAFNOSUPPORT)
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error ("socket: %m - make sure %s %s!",
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"CONFIG_PACKET and CONFIG_FILTER are defined",
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"in your kernel configuration");
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error("Open a socket for LPF: %m");
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}
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/* Bind to the interface name */
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memset (&sa, 0, sizeof sa);
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sa.sa_family = AF_PACKET;
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strncpy (sa.sa_data, (const char *)info -> ifp, sizeof sa.sa_data);
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if (bind (sock, &sa, sizeof sa)) {
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if (errno == ENOPROTOOPT || errno == EPROTONOSUPPORT ||
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errno == ESOCKTNOSUPPORT || errno == EPFNOSUPPORT ||
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errno == EAFNOSUPPORT)
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error ("socket: %m - make sure %s %s!",
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"CONFIG_PACKET and CONFIG_FILTER are defined",
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"in your kernel configuration");
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error("Bind socket to interface: %m");
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}
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return sock;
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}
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#endif /* USE_LPF_SEND || USE_LPF_RECEIVE */
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#ifdef USE_LPF_SEND
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void if_register_send (info)
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struct interface_info *info;
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{
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/* If we're using the lpf API for sending and receiving,
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we don't need to register this interface twice. */
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#ifndef USE_LPF_RECEIVE
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info -> wfdesc = if_register_lpf (info, interface);
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#else
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info -> wfdesc = info -> rfdesc;
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#endif
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if (!quiet_interface_discovery)
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note ("Sending on LPF/%s/%s/%s",
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info -> name,
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print_hw_addr (info -> hw_address.htype,
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info -> hw_address.hlen,
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info -> hw_address.haddr),
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(info -> shared_network ?
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info -> shared_network -> name : "unattached"));
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}
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#endif /* USE_LPF_SEND */
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#ifdef USE_LPF_RECEIVE
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/* Defined in bpf.c. We can't extern these in dhcpd.h without pulling
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in bpf includes... */
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extern struct sock_filter dhcp_bpf_filter [];
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extern int dhcp_bpf_filter_len;
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void if_register_receive (info)
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struct interface_info *info;
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{
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struct sock_fprog p;
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/* Open a LPF device and hang it on this interface... */
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info -> rfdesc = if_register_lpf (info);
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/* Set up the bpf filter program structure. This is defined in
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bpf.c */
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p.len = dhcp_bpf_filter_len;
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p.filter = dhcp_bpf_filter;
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/* Patch the server port into the LPF program...
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XXX changes to filter program may require changes
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to the insn number(s) used below! XXX */
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dhcp_bpf_filter [8].k = ntohs (local_port);
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if (setsockopt (info -> rfdesc, SOL_SOCKET, SO_ATTACH_FILTER, &p,
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sizeof p) < 0) {
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if (errno == ENOPROTOOPT || errno == EPROTONOSUPPORT ||
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errno == ESOCKTNOSUPPORT || errno == EPFNOSUPPORT ||
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errno == EAFNOSUPPORT)
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error ("socket: %m - make sure %s %s!",
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"CONFIG_PACKET and CONFIG_FILTER are defined",
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"in your kernel configuration");
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error ("Can't install packet filter program: %m");
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}
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if (!quiet_interface_discovery)
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note ("Listening on LPF/%s/%s/%s",
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info -> name,
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print_hw_addr (info -> hw_address.htype,
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info -> hw_address.hlen,
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info -> hw_address.haddr),
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(info -> shared_network ?
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info -> shared_network -> name : "unattached"));
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}
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#endif /* USE_LPF_RECEIVE */
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#ifdef USE_LPF_SEND
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ssize_t send_packet (interface, packet, raw, len, from, to, hto)
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struct interface_info *interface;
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struct packet *packet;
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struct dhcp_packet *raw;
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size_t len;
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struct in_addr from;
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struct sockaddr_in *to;
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struct hardware *hto;
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{
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int bufp = 0;
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unsigned char buf [1500];
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struct sockaddr sa;
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if (!strcmp (interface -> name, "fallback"))
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return send_fallback (interface, packet, raw,
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len, from, to, hto);
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/* Assemble the headers... */
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assemble_hw_header (interface, buf, &bufp, hto);
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assemble_udp_ip_header (interface, buf, &bufp, from.s_addr,
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to -> sin_addr.s_addr, to -> sin_port,
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(unsigned char *)raw, len);
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memcpy (buf + bufp, raw, len);
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/* For some reason, SOCK_PACKET sockets can't be connected,
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so we have to do a sentdo every time. */
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memset (&sa, 0, sizeof sa);
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sa.sa_family = AF_PACKET;
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strncpy (sa.sa_data,
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(const char *)interface -> ifp, sizeof sa.sa_data);
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return sendto (interface -> wfdesc, buf, bufp + len, 0,
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&sa, sizeof sa);
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}
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#endif /* USE_LPF_SEND */
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#ifdef USE_LPF_RECEIVE
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ssize_t receive_packet (interface, buf, len, from, hfrom)
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struct interface_info *interface;
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unsigned char *buf;
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size_t len;
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struct sockaddr_in *from;
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struct hardware *hfrom;
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{
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int nread;
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int length = 0;
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int offset = 0;
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unsigned char ibuf [1500];
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int bufix = 0;
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length = read (interface -> rfdesc, ibuf, sizeof ibuf);
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if (length <= 0)
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return length;
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bufix = 0;
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/* Decode the physical header... */
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offset = decode_hw_header (interface, ibuf, bufix, hfrom);
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/* If a physical layer checksum failed (dunno of any
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physical layer that supports this, but WTH), skip this
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packet. */
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if (offset < 0) {
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return 0;
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}
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bufix += offset;
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length -= offset;
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/* Decode the IP and UDP headers... */
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offset = decode_udp_ip_header (interface, ibuf, bufix,
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from, (unsigned char *)0, length);
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/* If the IP or UDP checksum was bad, skip the packet... */
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if (offset < 0)
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return 0;
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bufix += offset;
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length -= offset;
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/* Copy out the data in the packet... */
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memcpy (buf, &ibuf [bufix], length);
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return length;
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}
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int can_unicast_without_arp ()
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{
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return 1;
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}
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void maybe_setup_fallback ()
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{
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struct interface_info *fbi;
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fbi = setup_fallback ();
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if (fbi) {
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if_register_fallback (fbi);
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add_protocol ("fallback", fallback_interface -> wfdesc,
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fallback_discard, fallback_interface);
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}
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}
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#endif
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