1 | /* |
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2 | * dhcpcd - DHCP client daemon |
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3 | * Copyright (c) 2006-2008 Roy Marples <roy@marples.name> |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * 1. Redistributions of source code must retain the above copyright |
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9 | * notice, this list of conditions and the following disclaimer. |
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10 | * 2. Redistributions in binary form must reproduce the above copyright |
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11 | * notice, this list of conditions and the following disclaimer in the |
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12 | * documentation and/or other materials provided with the distribution. |
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13 | * |
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14 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
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15 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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16 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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17 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
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18 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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19 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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20 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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21 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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22 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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23 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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24 | * SUCH DAMAGE. |
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25 | */ |
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26 | |
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27 | #ifndef BPF_ETHCOOK |
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28 | # define BPF_ETHCOOK 0 |
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29 | #endif |
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30 | #ifndef BPF_WHOLEPACKET |
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31 | # define BPF_WHOLEPACKET ~0U |
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32 | #endif |
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33 | static const struct bpf_insn arp_bpf_filter [] = { |
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34 | #ifndef BPF_SKIPTYPE |
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35 | /* Make sure this is an ARP packet... */ |
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36 | BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12), |
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37 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_ARP, 0, 3), |
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38 | #endif |
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39 | /* Make sure this is an ARP REQUEST... */ |
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40 | BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20 + BPF_ETHCOOK), |
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41 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REQUEST, 2, 0), |
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42 | /* or ARP REPLY... */ |
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43 | BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20 + BPF_ETHCOOK), |
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44 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REPLY, 0, 1), |
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45 | /* If we passed all the tests, ask for the whole packet. */ |
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46 | BPF_STMT(BPF_RET + BPF_K, BPF_WHOLEPACKET), |
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47 | /* Otherwise, drop it. */ |
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48 | BPF_STMT(BPF_RET + BPF_K, 0), |
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49 | }; |
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50 | static const size_t arp_bpf_filter_len = |
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51 | sizeof(arp_bpf_filter) / sizeof(arp_bpf_filter[0]); |
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52 | |
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53 | |
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54 | /* dhcp_bpf_filter taken from bpf.c in dhcp-3.1.0 |
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55 | * |
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56 | * Copyright (c) 2004,2007 by Internet Systems Consortium, Inc. ("ISC") |
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57 | * Copyright (c) 1996-2003 by Internet Software Consortium |
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58 | * |
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59 | * Permission to use, copy, modify, and distribute this software for any |
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60 | * purpose with or without fee is hereby granted, provided that the above |
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61 | * copyright notice and this permission notice appear in all copies. |
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62 | * |
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63 | * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES |
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64 | * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
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65 | * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR |
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66 | * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
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67 | * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
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68 | * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT |
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69 | * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
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70 | * |
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71 | * Internet Systems Consortium, Inc. |
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72 | * 950 Charter Street |
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73 | * Redwood City, CA 94063 |
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74 | * <info@isc.org> |
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75 | * http://www.isc.org/ |
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76 | */ |
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77 | |
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78 | static const struct bpf_insn dhcp_bpf_filter [] = { |
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79 | #ifndef BPF_SKIPTYPE |
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80 | /* Make sure this is an IP packet... */ |
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81 | BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12), |
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82 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 8), |
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83 | #endif |
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84 | /* Make sure it's a UDP packet... */ |
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85 | BPF_STMT(BPF_LD + BPF_B + BPF_ABS, 23 + BPF_ETHCOOK), |
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86 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 0, 6), |
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87 | /* Make sure this isn't a fragment... */ |
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88 | BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20 + BPF_ETHCOOK), |
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89 | BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x1fff, 4, 0), |
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90 | /* Get the IP header length... */ |
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91 | BPF_STMT(BPF_LDX + BPF_B + BPF_MSH, 14 + BPF_ETHCOOK), |
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92 | /* Make sure it's to the right port... */ |
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93 | BPF_STMT(BPF_LD + BPF_H + BPF_IND, 16 + BPF_ETHCOOK), |
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94 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DHCP_CLIENT_PORT, 0, 1), |
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95 | /* If we passed all the tests, ask for the whole packet. */ |
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96 | BPF_STMT(BPF_RET + BPF_K, BPF_WHOLEPACKET), |
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97 | /* Otherwise, drop it. */ |
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98 | BPF_STMT(BPF_RET + BPF_K, 0), |
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99 | }; |
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100 | static const size_t dhcp_bpf_filter_len = |
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101 | sizeof(dhcp_bpf_filter) / sizeof(dhcp_bpf_filter[0]); |
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