Paul Stewart | 91a5aac | 2012-07-20 11:55:40 -0700 | [diff] [blame] | 1 | // Copyright (c) 2012 The Chromium OS Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #include "shill/arp_packet.h" |
| 6 | |
| 7 | #include <net/ethernet.h> |
| 8 | #include <net/if_arp.h> |
| 9 | #include <netinet/in.h> |
| 10 | #include <string.h> |
| 11 | |
Christopher Wiley | b691efd | 2012-08-09 13:51:51 -0700 | [diff] [blame] | 12 | #include "shill/logging.h" |
Paul Stewart | 91a5aac | 2012-07-20 11:55:40 -0700 | [diff] [blame] | 13 | |
| 14 | namespace shill { |
| 15 | |
Paul Stewart | ac1328e | 2012-07-20 11:55:40 -0700 | [diff] [blame] | 16 | const size_t ArpPacket::kMinPayloadSize = ETH_ZLEN - ETH_HLEN; |
| 17 | |
Paul Stewart | 91a5aac | 2012-07-20 11:55:40 -0700 | [diff] [blame] | 18 | ArpPacket::ArpPacket() |
| 19 | : local_ip_address_(IPAddress::kFamilyUnknown), |
| 20 | remote_ip_address_(IPAddress::kFamilyUnknown) {} |
| 21 | |
| 22 | ArpPacket::ArpPacket( |
| 23 | const IPAddress &local_ip, const IPAddress &remote_ip, |
| 24 | const ByteString &local_mac, const ByteString &remote_mac) |
| 25 | : local_ip_address_(local_ip), |
| 26 | remote_ip_address_(remote_ip), |
| 27 | local_mac_address_(local_mac), |
| 28 | remote_mac_address_(remote_mac) {} |
| 29 | |
| 30 | ArpPacket::~ArpPacket() {} |
| 31 | |
| 32 | // Format of an ARP packet (all multi-byte values are big-endian): |
| 33 | // |
| 34 | // Byte 0 Byte 1 Byte 2 Byte 3 |
| 35 | // +-----------------+-----------------+-----------------+-----------------+ |
| 36 | // | Format of hardware address (ether)| Format of Protocol Address (IP) | |
| 37 | // +-----------------+-----------------+-----------------------------------+ |
| 38 | // | Hardware Length | Protocol Length | ARP Protocol OpCode | |
| 39 | // +-----------------+-----------------+-----------------------------------+ |
| 40 | // |
| 41 | // plus a variable length section... |
| 42 | // |
| 43 | // +-----------------------------------------------------------------------+ |
| 44 | // | Sender Hardware Address (of length "Hardware Length")... | |
| 45 | // +-----------------------------------------------------------------------+ |
| 46 | // | Sender IP Address (of length "Protocol Length")... | |
| 47 | // +-----------------------------------------------------------------------+ |
| 48 | // | Target Hardware Address (of length "Hardware Length")... | |
| 49 | // +-----------------------------------------------------------------------+ |
| 50 | // | Target IP Address (of length "Protocol Length")... | |
| 51 | // +-----------------------------------------------------------------------+ |
| 52 | bool ArpPacket::ParseReply(const ByteString &packet) { |
| 53 | arphdr header; |
| 54 | if (packet.GetLength() < sizeof(header)) { |
| 55 | LOG(ERROR) << "Packet size " << packet.GetLength() |
| 56 | << " is too short to contain ARP header."; |
| 57 | return false; |
| 58 | } |
| 59 | |
| 60 | memcpy(&header, packet.GetConstData(), sizeof(header)); |
| 61 | |
| 62 | const uint16 hardware_type = ntohs(header.ar_hrd); |
| 63 | if (hardware_type != ARPHRD_ETHER) { |
| 64 | NOTIMPLEMENTED() << "Packet is of unknown ARPHRD type " |
| 65 | << hardware_type; |
| 66 | return false; |
| 67 | } |
| 68 | const uint16 protocol = ntohs(header.ar_pro); |
| 69 | IPAddress::Family family = IPAddress::kFamilyUnknown; |
| 70 | if (protocol == ETHERTYPE_IP) { |
| 71 | family = IPAddress::kFamilyIPv4; |
| 72 | } else if (protocol == ETHERTYPE_IPV6) { |
| 73 | family = IPAddress::kFamilyIPv6; |
| 74 | } else { |
| 75 | NOTIMPLEMENTED() << "Packet has unknown protocol " |
| 76 | << protocol; |
| 77 | return false; |
| 78 | } |
| 79 | if (header.ar_hln != ETH_ALEN) { |
| 80 | LOG(ERROR) << "Packet has unexpected hardware address length " |
| 81 | << static_cast<int>(header.ar_hln) << "; expected " << ETH_ALEN; |
| 82 | return false; |
| 83 | } |
| 84 | size_t ip_address_length = IPAddress::GetAddressLength(family); |
| 85 | if (header.ar_pln != ip_address_length) { |
| 86 | LOG(ERROR) << "Packet has unexpected protocol address length " |
| 87 | << static_cast<int>(header.ar_hln) << "; expected " |
| 88 | << ip_address_length; |
| 89 | return false; |
| 90 | } |
| 91 | const uint16 operation = ntohs(header.ar_op); |
| 92 | if (operation != ARPOP_REPLY) { |
| 93 | NOTIMPLEMENTED() << "Packet is not an ARP reply but of type " |
| 94 | << operation; |
| 95 | return false; |
| 96 | } |
| 97 | size_t min_packet_size = |
| 98 | sizeof(header) + 2 * ip_address_length + 2 * ETH_ALEN; |
| 99 | if (packet.GetLength() < min_packet_size) { |
| 100 | NOTIMPLEMENTED() << "Packet of size " |
| 101 | << packet.GetLength() |
| 102 | << " is too small to contain entire ARP payload; " |
| 103 | << "expected at least " |
| 104 | << min_packet_size; |
| 105 | return false; |
| 106 | } |
| 107 | local_mac_address_ = packet.GetSubstring(sizeof(header), ETH_ALEN); |
| 108 | local_ip_address_ = IPAddress(family, packet.GetSubstring( |
| 109 | sizeof(header) + ETH_ALEN, ip_address_length)); |
| 110 | remote_mac_address_ = packet.GetSubstring( |
| 111 | sizeof(header) + ETH_ALEN + ip_address_length, ETH_ALEN); |
| 112 | remote_ip_address_ = IPAddress(family, packet.GetSubstring( |
| 113 | sizeof(header) + ETH_ALEN * 2 + ip_address_length, ip_address_length)); |
| 114 | return true; |
| 115 | } |
| 116 | |
| 117 | // Output a payload from local parameters. |
| 118 | bool ArpPacket::FormatRequest(ByteString *packet) const { |
| 119 | if (!local_ip_address_.IsValid() || !remote_ip_address_.IsValid()) { |
| 120 | LOG(ERROR) << "Local or remote IP address is not valid."; |
| 121 | return false; |
| 122 | } |
| 123 | if (local_ip_address_.family() != remote_ip_address_.family()) { |
| 124 | LOG(ERROR) << "Local and remote IP address families do not match!"; |
| 125 | return false; |
| 126 | } |
| 127 | uint16 protocol; |
| 128 | IPAddress::Family family = local_ip_address_.family(); |
| 129 | if (family == IPAddress::kFamilyIPv4) { |
| 130 | protocol = ETHERTYPE_IP; |
| 131 | } else if (family == IPAddress::kFamilyIPv6) { |
| 132 | protocol = ETHERTYPE_IPV6; |
| 133 | } else { |
| 134 | NOTIMPLEMENTED() << "Address family " |
| 135 | << IPAddress::GetAddressFamilyName(family) |
| 136 | << " is not supported."; |
| 137 | return false; |
| 138 | } |
| 139 | size_t ip_address_length = IPAddress::GetAddressLength(family); |
| 140 | CHECK(ip_address_length < kuint8max); |
| 141 | if (local_mac_address_.GetLength() != ETH_ALEN || |
| 142 | remote_mac_address_.GetLength() != ETH_ALEN) { |
| 143 | LOG(ERROR) << "Local or remote MAC address length is incorrect."; |
| 144 | return false; |
| 145 | } |
| 146 | |
| 147 | arphdr header; |
| 148 | header.ar_hrd = htons(ARPHRD_ETHER); |
| 149 | header.ar_pro = htons(protocol); |
| 150 | header.ar_hln = ETH_ALEN; |
| 151 | header.ar_pln = ip_address_length; |
| 152 | header.ar_op = htons(ARPOP_REQUEST); |
| 153 | |
| 154 | *packet = ByteString(reinterpret_cast<const unsigned char *>(&header), |
| 155 | sizeof(header)); |
| 156 | |
| 157 | packet->Append(local_mac_address_); |
| 158 | packet->Append(local_ip_address_.address()); |
| 159 | packet->Append(remote_mac_address_); |
| 160 | packet->Append(remote_ip_address_.address()); |
| 161 | |
Paul Stewart | ac1328e | 2012-07-20 11:55:40 -0700 | [diff] [blame] | 162 | if (packet->GetLength() < kMinPayloadSize) { |
| 163 | packet->Append(ByteString(kMinPayloadSize - packet->GetLength())); |
| 164 | } |
| 165 | |
Paul Stewart | 91a5aac | 2012-07-20 11:55:40 -0700 | [diff] [blame] | 166 | return true; |
| 167 | } |
| 168 | |
| 169 | } // namespace shill |