| /* |
| * Copyright (c) 2020, The OpenThread Authors. |
| * 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 copyright holder 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 COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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. |
| */ |
| |
| /** |
| * @file |
| * This file implements checksum calculation. |
| */ |
| |
| #include "checksum.hpp" |
| |
| #include "common/code_utils.hpp" |
| #include "common/message.hpp" |
| #include "net/icmp6.hpp" |
| #include "net/tcp6.hpp" |
| #include "net/udp6.hpp" |
| |
| namespace ot { |
| |
| void Checksum::AddUint8(uint8_t aUint8) |
| { |
| uint16_t newValue = mValue; |
| |
| // BigEndian encoding: Even index is MSB and odd index is LSB. |
| |
| newValue += mAtOddIndex ? aUint8 : (static_cast<uint16_t>(aUint8) << 8); |
| |
| // Calculate one's complement sum. |
| |
| if (newValue < mValue) |
| { |
| newValue++; |
| } |
| |
| mValue = newValue; |
| mAtOddIndex = !mAtOddIndex; |
| } |
| |
| void Checksum::AddUint16(uint16_t aUint16) |
| { |
| // BigEndian encoding |
| AddUint8(static_cast<uint8_t>(aUint16 >> 8)); |
| AddUint8(static_cast<uint8_t>(aUint16 & 0xff)); |
| } |
| |
| void Checksum::AddData(const uint8_t *aBuffer, uint16_t aLength) |
| { |
| for (uint16_t i = 0; i < aLength; i++) |
| { |
| AddUint8(aBuffer[i]); |
| } |
| } |
| |
| void Checksum::WriteToMessage(uint16_t aOffset, Message &aMessage) const |
| { |
| uint16_t checksum = GetValue(); |
| |
| if (checksum != 0xffff) |
| { |
| checksum = ~checksum; |
| } |
| |
| checksum = Encoding::BigEndian::HostSwap16(checksum); |
| |
| aMessage.Write(aOffset, checksum); |
| } |
| |
| void Checksum::Calculate(const Ip6::Address &aSource, |
| const Ip6::Address &aDestination, |
| uint8_t aIpProto, |
| const Message & aMessage) |
| { |
| Message::Chunk chunk; |
| uint16_t length = aMessage.GetLength() - aMessage.GetOffset(); |
| |
| // Pseudo-header for checksum calculation (RFC-2460). |
| |
| AddData(aSource.GetBytes(), sizeof(Ip6::Address)); |
| AddData(aDestination.GetBytes(), sizeof(Ip6::Address)); |
| AddUint16(length); |
| AddUint16(static_cast<uint16_t>(aIpProto)); |
| |
| // Add message content (from offset to the end) to checksum. |
| |
| aMessage.GetFirstChunk(aMessage.GetOffset(), length, chunk); |
| |
| while (chunk.GetLength() > 0) |
| { |
| AddData(chunk.GetBytes(), chunk.GetLength()); |
| aMessage.GetNextChunk(length, chunk); |
| } |
| } |
| |
| Error Checksum::VerifyMessageChecksum(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo, uint8_t aIpProto) |
| { |
| Checksum checksum; |
| |
| checksum.Calculate(aMessageInfo.GetPeerAddr(), aMessageInfo.GetSockAddr(), aIpProto, aMessage); |
| |
| return (checksum.GetValue() == kValidRxChecksum) ? kErrorNone : kErrorDrop; |
| } |
| |
| void Checksum::UpdateMessageChecksum(Message & aMessage, |
| const Ip6::Address &aSource, |
| const Ip6::Address &aDestination, |
| uint8_t aIpProto) |
| { |
| uint16_t headerOffset; |
| Checksum checksum; |
| |
| switch (aIpProto) |
| { |
| case Ip6::kProtoTcp: |
| headerOffset = Ip6::Tcp::Header::kChecksumFieldOffset; |
| break; |
| |
| case Ip6::kProtoUdp: |
| headerOffset = Ip6::Udp::Header::kChecksumFieldOffset; |
| break; |
| |
| case Ip6::kProtoIcmp6: |
| headerOffset = Ip6::Icmp::Header::kChecksumFieldOffset; |
| break; |
| |
| default: |
| ExitNow(); |
| } |
| |
| checksum.Calculate(aSource, aDestination, aIpProto, aMessage); |
| checksum.WriteToMessage(aMessage.GetOffset() + headerOffset, aMessage); |
| |
| exit: |
| return; |
| } |
| |
| } // namespace ot |