1147072Sbrooks/* $OpenBSD: bpf.c,v 1.13 2004/05/05 14:28:58 deraadt Exp $ */ 2147072Sbrooks 3147072Sbrooks/* BPF socket interface code, originally contributed by Archie Cobbs. */ 4147072Sbrooks 5147072Sbrooks/* 6147072Sbrooks * Copyright (c) 1995, 1996, 1998, 1999 7147072Sbrooks * The Internet Software Consortium. All rights reserved. 8147072Sbrooks * 9147072Sbrooks * Redistribution and use in source and binary forms, with or without 10147072Sbrooks * modification, are permitted provided that the following conditions 11147072Sbrooks * are met: 12147072Sbrooks * 13147072Sbrooks * 1. Redistributions of source code must retain the above copyright 14147072Sbrooks * notice, this list of conditions and the following disclaimer. 15147072Sbrooks * 2. Redistributions in binary form must reproduce the above copyright 16147072Sbrooks * notice, this list of conditions and the following disclaimer in the 17147072Sbrooks * documentation and/or other materials provided with the distribution. 18147072Sbrooks * 3. Neither the name of The Internet Software Consortium nor the names 19147072Sbrooks * of its contributors may be used to endorse or promote products derived 20147072Sbrooks * from this software without specific prior written permission. 21147072Sbrooks * 22147072Sbrooks * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND 23147072Sbrooks * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, 24147072Sbrooks * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 25147072Sbrooks * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 26147072Sbrooks * DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR 27147072Sbrooks * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 28147072Sbrooks * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 29147072Sbrooks * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 30147072Sbrooks * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 31147072Sbrooks * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 32147072Sbrooks * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 33147072Sbrooks * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34147072Sbrooks * SUCH DAMAGE. 35147072Sbrooks * 36147072Sbrooks * This software has been written for the Internet Software Consortium 37147072Sbrooks * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie 38147072Sbrooks * Enterprises. To learn more about the Internet Software Consortium, 39147072Sbrooks * see ``http://www.vix.com/isc''. To learn more about Vixie 40147072Sbrooks * Enterprises, see ``http://www.vix.com''. 41147072Sbrooks */ 42147072Sbrooks 43149399Sbrooks#include <sys/cdefs.h> 44149399Sbrooks__FBSDID("$FreeBSD$"); 45149399Sbrooks 46255219Spjd#include <sys/capability.h> 47255219Spjd 48147072Sbrooks#include "dhcpd.h" 49252626Spjd#include "privsep.h" 50252628Spjd#include <sys/capability.h> 51147072Sbrooks#include <sys/ioctl.h> 52147072Sbrooks#include <sys/uio.h> 53147072Sbrooks 54147072Sbrooks#include <net/bpf.h> 55147072Sbrooks#include <netinet/in_systm.h> 56147072Sbrooks#include <netinet/ip.h> 57147072Sbrooks#include <netinet/udp.h> 58147072Sbrooks#include <netinet/if_ether.h> 59147072Sbrooks 60147072Sbrooks#define BPF_FORMAT "/dev/bpf%d" 61147072Sbrooks 62147072Sbrooks/* 63147072Sbrooks * Called by get_interface_list for each interface that's discovered. 64147072Sbrooks * Opens a packet filter for each interface and adds it to the select 65147072Sbrooks * mask. 66147072Sbrooks */ 67147072Sbrooksint 68252620Spjdif_register_bpf(struct interface_info *info, int flags) 69147072Sbrooks{ 70147072Sbrooks char filename[50]; 71147072Sbrooks int sock, b; 72147072Sbrooks 73147072Sbrooks /* Open a BPF device */ 74252620Spjd for (b = 0;; b++) { 75147072Sbrooks snprintf(filename, sizeof(filename), BPF_FORMAT, b); 76252620Spjd sock = open(filename, flags); 77147072Sbrooks if (sock < 0) { 78147072Sbrooks if (errno == EBUSY) 79147072Sbrooks continue; 80147072Sbrooks else 81147072Sbrooks error("Can't find free bpf: %m"); 82147072Sbrooks } else 83147072Sbrooks break; 84147072Sbrooks } 85147072Sbrooks 86147072Sbrooks /* Set the BPF device to point at this interface. */ 87147072Sbrooks if (ioctl(sock, BIOCSETIF, info->ifp) < 0) 88147072Sbrooks error("Can't attach interface %s to bpf device %s: %m", 89147072Sbrooks info->name, filename); 90147072Sbrooks 91147072Sbrooks return (sock); 92147072Sbrooks} 93147072Sbrooks 94252620Spjd/* 95252620Spjd * Packet write filter program: 96252620Spjd * 'ip and udp and src port bootps and dst port (bootps or bootpc)' 97252620Spjd */ 98252620Spjdstruct bpf_insn dhcp_bpf_wfilter[] = { 99252620Spjd BPF_STMT(BPF_LD + BPF_B + BPF_IND, 14), 100252620Spjd BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, (IPVERSION << 4) + 5, 0, 12), 101252620Spjd 102252620Spjd /* Make sure this is an IP packet... */ 103252620Spjd BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12), 104252620Spjd BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 10), 105252620Spjd 106252620Spjd /* Make sure it's a UDP packet... */ 107252620Spjd BPF_STMT(BPF_LD + BPF_B + BPF_ABS, 23), 108252620Spjd BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 0, 8), 109252620Spjd 110252620Spjd /* Make sure this isn't a fragment... */ 111252620Spjd BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20), 112252620Spjd BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x1fff, 6, 0), /* patched */ 113252620Spjd 114252620Spjd /* Get the IP header length... */ 115252620Spjd BPF_STMT(BPF_LDX + BPF_B + BPF_MSH, 14), 116252620Spjd 117252620Spjd /* Make sure it's from the right port... */ 118252620Spjd BPF_STMT(BPF_LD + BPF_H + BPF_IND, 14), 119252620Spjd BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 68, 0, 3), 120252620Spjd 121252620Spjd /* Make sure it is to the right ports ... */ 122252620Spjd BPF_STMT(BPF_LD + BPF_H + BPF_IND, 16), 123252620Spjd BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 67, 0, 1), 124252620Spjd 125252620Spjd /* If we passed all the tests, ask for the whole packet. */ 126252620Spjd BPF_STMT(BPF_RET+BPF_K, (u_int)-1), 127252620Spjd 128252620Spjd /* Otherwise, drop it. */ 129252620Spjd BPF_STMT(BPF_RET+BPF_K, 0), 130252620Spjd}; 131252620Spjd 132252620Spjdint dhcp_bpf_wfilter_len = sizeof(dhcp_bpf_wfilter) / sizeof(struct bpf_insn); 133252620Spjd 134147072Sbrooksvoid 135147072Sbrooksif_register_send(struct interface_info *info) 136147072Sbrooks{ 137255219Spjd cap_rights_t rights; 138252620Spjd struct bpf_version v; 139252620Spjd struct bpf_program p; 140198352Sphilip int sock, on = 1; 141198352Sphilip 142252620Spjd /* Open a BPF device and hang it on this interface... */ 143252620Spjd info->wfdesc = if_register_bpf(info, O_WRONLY); 144198352Sphilip 145252620Spjd /* Make sure the BPF version is in range... */ 146252620Spjd if (ioctl(info->wfdesc, BIOCVERSION, &v) < 0) 147252620Spjd error("Can't get BPF version: %m"); 148252620Spjd 149252620Spjd if (v.bv_major != BPF_MAJOR_VERSION || 150252620Spjd v.bv_minor < BPF_MINOR_VERSION) 151252620Spjd error("Kernel BPF version out of range - recompile dhcpd!"); 152252620Spjd 153252620Spjd /* Set up the bpf write filter program structure. */ 154252620Spjd p.bf_len = dhcp_bpf_wfilter_len; 155252620Spjd p.bf_insns = dhcp_bpf_wfilter; 156252620Spjd 157252620Spjd if (dhcp_bpf_wfilter[7].k == 0x1fff) 158252620Spjd dhcp_bpf_wfilter[7].k = htons(IP_MF|IP_OFFMASK); 159252620Spjd 160252620Spjd if (ioctl(info->wfdesc, BIOCSETWF, &p) < 0) 161252620Spjd error("Can't install write filter program: %m"); 162252620Spjd 163252620Spjd if (ioctl(info->wfdesc, BIOCLOCK, NULL) < 0) 164252620Spjd error("Cannot lock bpf"); 165252620Spjd 166255219Spjd cap_rights_init(&rights, CAP_WRITE); 167255219Spjd if (cap_rights_limit(info->wfdesc, &rights) < 0 && errno != ENOSYS) 168252628Spjd error("Can't limit bpf descriptor: %m"); 169252628Spjd 170198352Sphilip /* 171198352Sphilip * Use raw socket for unicast send. 172198352Sphilip */ 173198352Sphilip if ((sock = socket(AF_INET, SOCK_RAW, IPPROTO_UDP)) == -1) 174198352Sphilip error("socket(SOCK_RAW): %m"); 175198352Sphilip if (setsockopt(sock, IPPROTO_IP, IP_HDRINCL, &on, 176198352Sphilip sizeof(on)) == -1) 177198352Sphilip error("setsockopt(IP_HDRINCL): %m"); 178198352Sphilip info->ufdesc = sock; 179147072Sbrooks} 180147072Sbrooks 181147072Sbrooks/* 182147072Sbrooks * Packet filter program... 183147072Sbrooks * 184147072Sbrooks * XXX: Changes to the filter program may require changes to the 185147072Sbrooks * constant offsets used in if_register_send to patch the BPF program! 186147072Sbrooks */ 187147072Sbrooksstruct bpf_insn dhcp_bpf_filter[] = { 188147072Sbrooks /* Make sure this is an IP packet... */ 189147072Sbrooks BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12), 190147072Sbrooks BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 8), 191147072Sbrooks 192147072Sbrooks /* Make sure it's a UDP packet... */ 193147072Sbrooks BPF_STMT(BPF_LD + BPF_B + BPF_ABS, 23), 194147072Sbrooks BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 0, 6), 195147072Sbrooks 196147072Sbrooks /* Make sure this isn't a fragment... */ 197147072Sbrooks BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20), 198147072Sbrooks BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x1fff, 4, 0), 199147072Sbrooks 200147072Sbrooks /* Get the IP header length... */ 201147072Sbrooks BPF_STMT(BPF_LDX + BPF_B + BPF_MSH, 14), 202147072Sbrooks 203147072Sbrooks /* Make sure it's to the right port... */ 204147072Sbrooks BPF_STMT(BPF_LD + BPF_H + BPF_IND, 16), 205147072Sbrooks BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 67, 0, 1), /* patch */ 206147072Sbrooks 207147072Sbrooks /* If we passed all the tests, ask for the whole packet. */ 208147072Sbrooks BPF_STMT(BPF_RET+BPF_K, (u_int)-1), 209147072Sbrooks 210147072Sbrooks /* Otherwise, drop it. */ 211147072Sbrooks BPF_STMT(BPF_RET+BPF_K, 0), 212147072Sbrooks}; 213147072Sbrooks 214147072Sbrooksint dhcp_bpf_filter_len = sizeof(dhcp_bpf_filter) / sizeof(struct bpf_insn); 215147072Sbrooks 216147072Sbrooksvoid 217147072Sbrooksif_register_receive(struct interface_info *info) 218147072Sbrooks{ 219252628Spjd static const unsigned long cmds[2] = { SIOCGIFFLAGS, SIOCGIFMEDIA }; 220255219Spjd cap_rights_t rights; 221147072Sbrooks struct bpf_version v; 222147072Sbrooks struct bpf_program p; 223147072Sbrooks int flag = 1, sz; 224147072Sbrooks 225147072Sbrooks /* Open a BPF device and hang it on this interface... */ 226252620Spjd info->rfdesc = if_register_bpf(info, O_RDONLY); 227147072Sbrooks 228147072Sbrooks /* Make sure the BPF version is in range... */ 229147072Sbrooks if (ioctl(info->rfdesc, BIOCVERSION, &v) < 0) 230147072Sbrooks error("Can't get BPF version: %m"); 231147072Sbrooks 232147072Sbrooks if (v.bv_major != BPF_MAJOR_VERSION || 233147072Sbrooks v.bv_minor < BPF_MINOR_VERSION) 234147072Sbrooks error("Kernel BPF version out of range - recompile dhcpd!"); 235147072Sbrooks 236147072Sbrooks /* 237147072Sbrooks * Set immediate mode so that reads return as soon as a packet 238147072Sbrooks * comes in, rather than waiting for the input buffer to fill 239147072Sbrooks * with packets. 240147072Sbrooks */ 241147072Sbrooks if (ioctl(info->rfdesc, BIOCIMMEDIATE, &flag) < 0) 242147072Sbrooks error("Can't set immediate mode on bpf device: %m"); 243147072Sbrooks 244147072Sbrooks /* Get the required BPF buffer length from the kernel. */ 245147072Sbrooks if (ioctl(info->rfdesc, BIOCGBLEN, &sz) < 0) 246147072Sbrooks error("Can't get bpf buffer length: %m"); 247147072Sbrooks info->rbuf_max = sz; 248147072Sbrooks info->rbuf = malloc(info->rbuf_max); 249147072Sbrooks if (!info->rbuf) 250147072Sbrooks error("Can't allocate %lu bytes for bpf input buffer.", 251147072Sbrooks (unsigned long)info->rbuf_max); 252147072Sbrooks info->rbuf_offset = 0; 253147072Sbrooks info->rbuf_len = 0; 254147072Sbrooks 255147072Sbrooks /* Set up the bpf filter program structure. */ 256147072Sbrooks p.bf_len = dhcp_bpf_filter_len; 257147072Sbrooks p.bf_insns = dhcp_bpf_filter; 258147072Sbrooks 259147072Sbrooks /* Patch the server port into the BPF program... 260147072Sbrooks * 261147072Sbrooks * XXX: changes to filter program may require changes to the 262147072Sbrooks * insn number(s) used below! 263147072Sbrooks */ 264147072Sbrooks dhcp_bpf_filter[8].k = LOCAL_PORT; 265147072Sbrooks 266147072Sbrooks if (ioctl(info->rfdesc, BIOCSETF, &p) < 0) 267147072Sbrooks error("Can't install packet filter program: %m"); 268147072Sbrooks 269147072Sbrooks if (ioctl(info->rfdesc, BIOCLOCK, NULL) < 0) 270147072Sbrooks error("Cannot lock bpf"); 271252628Spjd 272261828Sbrueffer cap_rights_init(&rights, CAP_IOCTL, CAP_EVENT, CAP_READ); 273255219Spjd if (cap_rights_limit(info->rfdesc, &rights) < 0 && errno != ENOSYS) 274252628Spjd error("Can't limit bpf descriptor: %m"); 275252628Spjd if (cap_ioctls_limit(info->rfdesc, cmds, 2) < 0 && errno != ENOSYS) 276252628Spjd error("Can't limit ioctls for bpf descriptor: %m"); 277147072Sbrooks} 278147072Sbrooks 279252618Spjdvoid 280252626Spjdsend_packet_unpriv(int privfd, struct dhcp_packet *raw, size_t len, 281252626Spjd struct in_addr from, struct in_addr to) 282147072Sbrooks{ 283252626Spjd struct imsg_hdr hdr; 284252626Spjd struct buf *buf; 285252626Spjd int errs; 286252626Spjd 287252626Spjd hdr.code = IMSG_SEND_PACKET; 288252626Spjd hdr.len = sizeof(hdr) + 289252626Spjd sizeof(size_t) + len + 290252626Spjd sizeof(from) + sizeof(to); 291252626Spjd 292252626Spjd if ((buf = buf_open(hdr.len)) == NULL) 293252626Spjd error("buf_open: %m"); 294252626Spjd 295252626Spjd errs = 0; 296252626Spjd errs += buf_add(buf, &hdr, sizeof(hdr)); 297252626Spjd errs += buf_add(buf, &len, sizeof(len)); 298252626Spjd errs += buf_add(buf, raw, len); 299252626Spjd errs += buf_add(buf, &from, sizeof(from)); 300252626Spjd errs += buf_add(buf, &to, sizeof(to)); 301252626Spjd if (errs) 302252626Spjd error("buf_add: %m"); 303252626Spjd 304252626Spjd if (buf_close(privfd, buf) == -1) 305252626Spjd error("buf_close: %m"); 306252626Spjd} 307252626Spjd 308252626Spjdvoid 309252626Spjdsend_packet_priv(struct interface_info *interface, struct imsg_hdr *hdr, int fd) 310252626Spjd{ 311147072Sbrooks unsigned char buf[256]; 312147072Sbrooks struct iovec iov[2]; 313198352Sphilip struct msghdr msg; 314252626Spjd struct dhcp_packet raw; 315252626Spjd size_t len; 316252626Spjd struct in_addr from, to; 317147072Sbrooks int result, bufp = 0; 318147072Sbrooks 319252626Spjd if (hdr->len < sizeof(*hdr) + sizeof(size_t)) 320252626Spjd error("corrupted message received"); 321252626Spjd buf_read(fd, &len, sizeof(len)); 322252626Spjd if (hdr->len != sizeof(*hdr) + sizeof(size_t) + len + 323252626Spjd sizeof(from) + sizeof(to)) { 324252626Spjd error("corrupted message received"); 325252626Spjd } 326252626Spjd if (len > sizeof(raw)) 327252626Spjd error("corrupted message received"); 328252626Spjd buf_read(fd, &raw, len); 329252626Spjd buf_read(fd, &from, sizeof(from)); 330252626Spjd buf_read(fd, &to, sizeof(to)); 331252626Spjd 332147072Sbrooks /* Assemble the headers... */ 333252616Spjd if (to.s_addr == INADDR_BROADCAST) 334252615Spjd assemble_hw_header(interface, buf, &bufp); 335252616Spjd assemble_udp_ip_header(buf, &bufp, from.s_addr, to.s_addr, 336252626Spjd htons(REMOTE_PORT), (unsigned char *)&raw, len); 337147072Sbrooks 338252619Spjd iov[0].iov_base = buf; 339147072Sbrooks iov[0].iov_len = bufp; 340252626Spjd iov[1].iov_base = &raw; 341147072Sbrooks iov[1].iov_len = len; 342147072Sbrooks 343198352Sphilip /* Fire it off */ 344252616Spjd if (to.s_addr == INADDR_BROADCAST) 345198352Sphilip result = writev(interface->wfdesc, iov, 2); 346198352Sphilip else { 347252616Spjd struct sockaddr_in sato; 348252616Spjd 349252616Spjd sato.sin_addr = to; 350252616Spjd sato.sin_port = htons(REMOTE_PORT); 351252616Spjd sato.sin_family = AF_INET; 352252616Spjd sato.sin_len = sizeof(sato); 353252616Spjd 354198352Sphilip memset(&msg, 0, sizeof(msg)); 355252616Spjd msg.msg_name = (struct sockaddr *)&sato; 356252616Spjd msg.msg_namelen = sizeof(sato); 357198352Sphilip msg.msg_iov = iov; 358198352Sphilip msg.msg_iovlen = 2; 359198352Sphilip result = sendmsg(interface->ufdesc, &msg, 0); 360198352Sphilip } 361198352Sphilip 362147072Sbrooks if (result < 0) 363147072Sbrooks warning("send_packet: %m"); 364147072Sbrooks} 365147072Sbrooks 366147072Sbrooksssize_t 367147072Sbrooksreceive_packet(struct interface_info *interface, unsigned char *buf, 368147072Sbrooks size_t len, struct sockaddr_in *from, struct hardware *hfrom) 369147072Sbrooks{ 370147072Sbrooks int length = 0, offset = 0; 371147072Sbrooks struct bpf_hdr hdr; 372147072Sbrooks 373147072Sbrooks /* 374147072Sbrooks * All this complexity is because BPF doesn't guarantee that 375147072Sbrooks * only one packet will be returned at a time. We're getting 376147072Sbrooks * what we deserve, though - this is a terrible abuse of the BPF 377147072Sbrooks * interface. Sigh. 378147072Sbrooks */ 379147072Sbrooks 380147072Sbrooks /* Process packets until we get one we can return or until we've 381147072Sbrooks * done a read and gotten nothing we can return... 382147072Sbrooks */ 383147072Sbrooks do { 384147072Sbrooks /* If the buffer is empty, fill it. */ 385162641Sbrooks if (interface->rbuf_offset >= interface->rbuf_len) { 386147072Sbrooks length = read(interface->rfdesc, interface->rbuf, 387147072Sbrooks interface->rbuf_max); 388147072Sbrooks if (length <= 0) 389147072Sbrooks return (length); 390147072Sbrooks interface->rbuf_offset = 0; 391147072Sbrooks interface->rbuf_len = length; 392147072Sbrooks } 393147072Sbrooks 394147072Sbrooks /* 395147072Sbrooks * If there isn't room for a whole bpf header, something 396147072Sbrooks * went wrong, but we'll ignore it and hope it goes 397147072Sbrooks * away... XXX 398147072Sbrooks */ 399147072Sbrooks if (interface->rbuf_len - interface->rbuf_offset < 400147072Sbrooks sizeof(hdr)) { 401147072Sbrooks interface->rbuf_offset = interface->rbuf_len; 402147072Sbrooks continue; 403147072Sbrooks } 404147072Sbrooks 405147072Sbrooks /* Copy out a bpf header... */ 406147072Sbrooks memcpy(&hdr, &interface->rbuf[interface->rbuf_offset], 407147072Sbrooks sizeof(hdr)); 408147072Sbrooks 409147072Sbrooks /* 410147072Sbrooks * If the bpf header plus data doesn't fit in what's 411147072Sbrooks * left of the buffer, stick head in sand yet again... 412147072Sbrooks */ 413147072Sbrooks if (interface->rbuf_offset + hdr.bh_hdrlen + hdr.bh_caplen > 414147072Sbrooks interface->rbuf_len) { 415147072Sbrooks interface->rbuf_offset = interface->rbuf_len; 416147072Sbrooks continue; 417147072Sbrooks } 418147072Sbrooks 419148451Sbrooks /* Skip over the BPF header... */ 420148451Sbrooks interface->rbuf_offset += hdr.bh_hdrlen; 421148451Sbrooks 422147072Sbrooks /* 423147072Sbrooks * If the captured data wasn't the whole packet, or if 424147072Sbrooks * the packet won't fit in the input buffer, all we can 425147072Sbrooks * do is drop it. 426147072Sbrooks */ 427147072Sbrooks if (hdr.bh_caplen != hdr.bh_datalen) { 428148484Sbrooks interface->rbuf_offset = 429148484Sbrooks BPF_WORDALIGN(interface->rbuf_offset + 430148484Sbrooks hdr.bh_caplen); 431147072Sbrooks continue; 432147072Sbrooks } 433147072Sbrooks 434147072Sbrooks /* Decode the physical header... */ 435147072Sbrooks offset = decode_hw_header(interface->rbuf, 436147072Sbrooks interface->rbuf_offset, hfrom); 437147072Sbrooks 438147072Sbrooks /* 439147072Sbrooks * If a physical layer checksum failed (dunno of any 440147072Sbrooks * physical layer that supports this, but WTH), skip 441147072Sbrooks * this packet. 442147072Sbrooks */ 443147072Sbrooks if (offset < 0) { 444148484Sbrooks interface->rbuf_offset = 445148484Sbrooks BPF_WORDALIGN(interface->rbuf_offset + 446148484Sbrooks hdr.bh_caplen); 447147072Sbrooks continue; 448147072Sbrooks } 449147072Sbrooks interface->rbuf_offset += offset; 450147072Sbrooks hdr.bh_caplen -= offset; 451147072Sbrooks 452147072Sbrooks /* Decode the IP and UDP headers... */ 453147072Sbrooks offset = decode_udp_ip_header(interface->rbuf, 454147072Sbrooks interface->rbuf_offset, from, NULL, hdr.bh_caplen); 455147072Sbrooks 456147072Sbrooks /* If the IP or UDP checksum was bad, skip the packet... */ 457147072Sbrooks if (offset < 0) { 458148484Sbrooks interface->rbuf_offset = 459148484Sbrooks BPF_WORDALIGN(interface->rbuf_offset + 460148484Sbrooks hdr.bh_caplen); 461147072Sbrooks continue; 462147072Sbrooks } 463147072Sbrooks interface->rbuf_offset += offset; 464147072Sbrooks hdr.bh_caplen -= offset; 465147072Sbrooks 466147072Sbrooks /* 467147072Sbrooks * If there's not enough room to stash the packet data, 468147072Sbrooks * we have to skip it (this shouldn't happen in real 469147072Sbrooks * life, though). 470147072Sbrooks */ 471147072Sbrooks if (hdr.bh_caplen > len) { 472148484Sbrooks interface->rbuf_offset = 473148484Sbrooks BPF_WORDALIGN(interface->rbuf_offset + 474148484Sbrooks hdr.bh_caplen); 475147072Sbrooks continue; 476147072Sbrooks } 477147072Sbrooks 478147072Sbrooks /* Copy out the data in the packet... */ 479147072Sbrooks memcpy(buf, interface->rbuf + interface->rbuf_offset, 480147072Sbrooks hdr.bh_caplen); 481148484Sbrooks interface->rbuf_offset = 482148484Sbrooks BPF_WORDALIGN(interface->rbuf_offset + 483148484Sbrooks hdr.bh_caplen); 484147072Sbrooks return (hdr.bh_caplen); 485147072Sbrooks } while (!length); 486147072Sbrooks return (0); 487147072Sbrooks} 488