From 31c08e370fa796db9ee71dadc4528b09e176a460 Mon Sep 17 00:00:00 2001 From: Ted Lemon Date: Tue, 22 Dec 1998 22:34:54 +0000 Subject: [PATCH] Linux Packet Filter --- common/lpf.c | 252 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 252 insertions(+) create mode 100644 common/lpf.c diff --git a/common/lpf.c b/common/lpf.c new file mode 100644 index 00000000..7069c321 --- /dev/null +++ b/common/lpf.c @@ -0,0 +1,252 @@ +/* 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 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 +#include + +#include +#include +#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