/* lpf.c Linux packet filter code, contributed by Brian Murrel at Interlinx Support Services in Vancouver, B.C. */ /* * Copyright (c) 1995, 1996, 1998, 1999 * 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 1.1.1.4 1999/03/29 23:00:52 mellon Exp $ Copyright (c) 1995, 1996, 1998, 1999 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 #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_PACKET, SOCK_PACKET, htons(ETH_P_ALL))) < 0) { if (errno == ENOPROTOOPT || errno == EPROTONOSUPPORT || errno == ESOCKTNOSUPPORT || errno == EPFNOSUPPORT || errno == EAFNOSUPPORT || errno == EINVAL) { warn ("socket: %m"); error ("Make sure to set %s %s!", "CONFIG_PACKET=y and CONFIG_FILTER=y", "in your kernel configuration"); } error("Open a socket for LPF: %m"); } /* Bind to the interface name */ memset (&sa, 0, sizeof sa); sa.sa_family = AF_PACKET; strncpy (sa.sa_data, (const char *)info -> ifp, sizeof sa.sa_data); if (bind (sock, &sa, sizeof sa)) { if (errno == ENOPROTOOPT || errno == EPROTONOSUPPORT || errno == ESOCKTNOSUPPORT || errno == EPFNOSUPPORT || errno == EAFNOSUPPORT || errno == EINVAL) { warn ("bind: %m"); error ("Set %s %s!", "CONFIG_PACKET=y and CONFIG_FILTER=y", "in your kernel configuration"); } 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%s", info -> name, print_hw_addr (info -> hw_address.htype, info -> hw_address.hlen, info -> hw_address.haddr), (info -> shared_network ? "/" : ""), (info -> shared_network ? info -> shared_network -> name : "")); } #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 sock_filter dhcp_bpf_filter []; extern int dhcp_bpf_filter_len; void if_register_receive (info) struct interface_info *info; { struct sock_fprog p; /* 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.len = dhcp_bpf_filter_len; p.filter = 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) { if (errno == ENOPROTOOPT || errno == EPROTONOSUPPORT || errno == ESOCKTNOSUPPORT || errno == EPFNOSUPPORT || errno == EAFNOSUPPORT) error ("socket: %m - make sure %s %s!", "CONFIG_PACKET and CONFIG_FILTER are defined", "in your kernel configuration"); error ("Can't install packet filter program: %m"); } if (!quiet_interface_discovery) note ("Listening on LPF/%s/%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 ? info -> shared_network -> name : "")); } #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]; struct sockaddr sa; int result; 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); /* For some reason, SOCK_PACKET sockets can't be connected, so we have to do a sentdo every time. */ memset (&sa, 0, sizeof sa); sa.sa_family = AF_PACKET; strncpy (sa.sa_data, (const char *)interface -> ifp, sizeof sa.sa_data); result = sendto (interface -> wfdesc, buf, bufp + len, 0, &sa, sizeof sa); if (result < 0) warn ("send_packet: %m"); return result; } #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]; int bufix = 0; length = read (interface -> rfdesc, ibuf, sizeof ibuf); if (length <= 0) return length; bufix = 0; /* 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; } int can_receive_unicast_unconfigured (ip) struct interface_info *ip; { 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