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Diffstat (limited to 'contrib/isc-dhcp/common/bpf.c')
| -rw-r--r-- | contrib/isc-dhcp/common/bpf.c | 386 |
1 files changed, 386 insertions, 0 deletions
diff --git a/contrib/isc-dhcp/common/bpf.c b/contrib/isc-dhcp/common/bpf.c new file mode 100644 index 000000000000..e47aa1f7822c --- /dev/null +++ b/contrib/isc-dhcp/common/bpf.c @@ -0,0 +1,386 @@ +/* bpf.c + + BPF socket interface code, originally contributed by Archie Cobbs. */ + +/* + * Copyright (c) 1995, 1996 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: bpf.c,v 1.19 1997/10/20 21:47:13 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium. All rights reserved.\n"; +#endif /* not lint */ + +#include "dhcpd.h" +#if defined (USE_BPF_SEND) || defined (USE_BPF_RECEIVE) +#include <sys/ioctl.h> +#include <sys/uio.h> + +#include <net/bpf.h> +#ifdef NEED_OSF_PFILT_HACKS +#include <net/pfilt.h> +#endif +#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_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. */ + +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++) { +#ifndef NO_SNPRINTF + snprintf(filename, sizeof(filename), BPF_FORMAT, b); +#else + sprintf(filename, BPF_FORMAT, b); +#endif + sock = open (filename, O_RDWR, 0); + if (sock < 0) { + if (errno == EBUSY) { + continue; + } else { + error ("Can't find free bpf: %m"); + } + } else { + break; + } + } + + /* Set the BPF device to point at this interface. */ + if (ioctl (sock, BIOCSETIF, info -> ifp) < 0) + error ("Can't attach interface %s to bpf device %s: %m", + info -> name, filename); + + 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) + note ("Sending on BPF/%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_BPF_SEND */ + +#ifdef USE_BPF_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 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), +}; + +void if_register_receive (info) + struct interface_info *info; +{ + int flag = 1; + struct bpf_version v; + u_int32_t addr; + struct bpf_program p; + u_int32_t bits; + + /* 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) + error ("Can't get BPF version: %m"); + + if (v.bv_major != BPF_MAJOR_VERSION || + v.bv_minor < BPF_MINOR_VERSION) + error ("Kernel BPF version out of range - recompile dhcpd!"); + + /* 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) + error ("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) + error ("Can't set ALLOWCOPYALL: %m"); + + /* Clear all the packet filter mode bits first... */ + bits = 0; + if (ioctl (info -> rfdesc, EIOCMBIS, &bits) < 0) + error ("Can't clear pfilt bits: %m"); + + /* Set the ENBATCH, ENCOPYALL, ENBPFHDR bits... */ + bits = ENBATCH | ENCOPYALL | ENBPFHDR; + if (ioctl (info -> rfdesc, EIOCMBIS, &bits) < 0) + error ("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) + error ("Can't get bpf buffer length: %m"); + info -> rbuf = malloc (info -> rbuf_max); + if (!info -> rbuf) + error ("Can't allocate %d bytes for bpf input buffer."); + info -> rbuf_offset = 0; + info -> rbuf_len = 0; + + /* Set up the bpf filter program structure. */ + p.bf_len = sizeof filter / sizeof (struct bpf_insn); + p.bf_insns = 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 */ + filter [8].k = ntohs (local_port); + + if (ioctl (info -> rfdesc, BIOCSETF, &p) < 0) + error ("Can't install packet filter program: %m"); + if (!quiet_interface_discovery) + note ("Listening on BPF/%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_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; +{ + int bufp = 0; + unsigned char buf [256]; + struct iovec iov [2]; + + /* 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); + + /* Fire it off */ + iov [0].iov_base = (char *)buf; + iov [0].iov_len = bufp; + iov [1].iov_base = (char *)raw; + iov [1].iov_len = len; + + return writev(interface -> wfdesc, iov, 2); +} +#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; + + /* 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, + interface -> rbuf_max); + if (length <= 0) + return length; + interface -> rbuf_offset = 0; + interface -> rbuf_len = 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 += + 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 += 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, + (unsigned char *)0, + hdr.bh_caplen); + + /* If the IP or UDP checksum was bad, skip the packet... */ + if (offset < 0) { + interface -> rbuf_offset += hdr.bh_caplen; + continue; + } + 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 += hdr.bh_caplen; + continue; + } + + /* Copy out the data in the packet... */ + memcpy (buf, interface -> rbuf + interface -> rbuf_offset, + hdr.bh_caplen); + interface -> rbuf_offset += hdr.bh_caplen; + return hdr.bh_caplen; + } while (!length); + return 0; +} +#endif |