mirror of
https://github.com/zaphar/icmp-socket.git
synced 2025-07-22 19:30:05 -04:00
329 lines
10 KiB
Rust
329 lines
10 KiB
Rust
// Copyright 2021 Jeremy Wall
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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use std::net::Ipv6Addr;
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use byteorder::{ByteOrder, BigEndian};
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fn ipv6_sum_words(ip: &Ipv6Addr) -> u32 {
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ip.segments().iter().map(|x| *x as u32).sum()
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}
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fn sum_big_endian_words(bs: &[u8]) -> u32 {
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if bs.len() == 0 {
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return 0;
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}
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let len = bs.len();
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let mut data = &bs[..];
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let mut sum = 032;
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// We need to stop when we have less than 2 bytes left.
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while data.len() >= 2 {
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sum += BigEndian::read_u16(&data[0..2]) as u32;
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// remove the first two now that we've already summed them
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data = &data[2..];
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}
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if len % 2 != 0 { // If odd then checksum the last byte
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sum += (bs[len - 1] as u32) << 8;
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}
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return sum;
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}
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pub enum Icmpv6Message {
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// NOTE(JWALL): All of the below integers should be parsed as big endian on the
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// wire.
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Unreachable {
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_unused: u32,
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invoking_packet: Vec<u8>,
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},
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PacketTooBig {
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mtu: u32,
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invoking_packet: Vec<u8>,
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},
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TimeExceeded {
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_unused: u32,
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invoking_packet: Vec<u8>,
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},
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ParameterProblem {
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pointer: u32,
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invoking_packet: Vec<u8>,
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},
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PrivateExperimental {
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padding: u32,
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payload: Vec<u8>,
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},
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EchoRequest {
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identifier: u16,
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sequence: u16,
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payload: Vec<u8>,
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},
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EchoReply {
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identifier: u16,
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sequence: u16,
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payload: Vec<u8>,
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}
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}
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use Icmpv6Message::{Unreachable, PacketTooBig, TimeExceeded, ParameterProblem, PrivateExperimental, EchoRequest, EchoReply};
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impl Icmpv6Message {
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pub fn get_bytes(&self) -> Vec<u8> {
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let mut bytes = Vec::new();
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match self {
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Unreachable {_unused: field1, invoking_packet: field2 } |
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PacketTooBig {mtu: field1, invoking_packet: field2 } |
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TimeExceeded {_unused: field1, invoking_packet: field2 } |
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ParameterProblem {pointer: field1, invoking_packet: field2 } |
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PrivateExperimental {padding: field1, payload: field2 } => {
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let mut buf = vec![0; 4];
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BigEndian::write_u32(&mut buf, *field1);
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bytes.append(&mut buf);
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bytes.extend_from_slice(field2);
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},
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EchoRequest{
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identifier,
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sequence,
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payload,
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} | EchoReply{
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identifier,
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sequence,
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payload,
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} => {
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let mut buf = vec![0; 2];
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BigEndian::write_u16(&mut buf, *identifier);
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bytes.append(&mut buf);
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buf.resize(2, 0);
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BigEndian::write_u16(&mut buf, *sequence);
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bytes.append(&mut buf);
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bytes.extend_from_slice(payload);
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}
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}
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bytes
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}
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}
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pub struct Icmpv6Packet {
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// NOTE(JWALL): All of the below integers should be parsed as big endian on the
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// wire.
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pub typ: u8,
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pub code: u8,
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pub checksum: u16,
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pub message: Icmpv6Message,
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}
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#[derive(Debug)]
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pub enum PacketParseError {
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PacketTooSmall(usize),
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UnrecognizedICMPType,
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}
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impl Icmpv6Packet {
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/// Construct a packet by parsing the provided bytes.
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pub fn parse<B: AsRef<[u8]>>(bytes: B) -> Result<Self, PacketParseError> {
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let bytes = bytes.as_ref();
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// NOTE(jwall): All ICMP packets are at least 8 bytes long.
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if bytes.len() < 8 {
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return Err(PacketParseError::PacketTooSmall(bytes.len()));
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}
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let (typ, code, checksum) = (bytes[0], bytes[1], BigEndian::read_u16(&bytes[2..3]));
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let next_field = BigEndian::read_u32(&bytes[4..7]);
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let payload = bytes[8..].to_owned();
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let message = match typ {
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1 => Unreachable{
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_unused: next_field,
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invoking_packet: payload,
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},
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2 => PacketTooBig{
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mtu: next_field,
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invoking_packet: payload,
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},
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3 => TimeExceeded{
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_unused: next_field,
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invoking_packet: payload,
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},
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4 => ParameterProblem {
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pointer: next_field,
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invoking_packet: payload,
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},
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100 | 101 | 200 | 201 => PrivateExperimental{
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padding: next_field,
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payload: payload,
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},
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128 => EchoRequest{
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identifier: BigEndian::read_u16(&bytes[4..5]),
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sequence: BigEndian::read_u16(&bytes[6..7]),
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payload: payload,
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},
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129 => EchoReply{
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identifier: BigEndian::read_u16(&bytes[4..5]),
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sequence: BigEndian::read_u16(&bytes[6..7]),
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payload: payload,
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},
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_ => return Err(PacketParseError::UnrecognizedICMPType),
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};
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return Ok(Icmpv6Packet{
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typ: typ,
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code: code,
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checksum: checksum,
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message: message,
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})
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}
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/// Get this packet serialized to bytes suitable for sending on the wire.
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pub fn get_bytes(&self, with_checksum: bool) -> Vec<u8> {
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let mut bytes = Vec::new();
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bytes.push(self.typ);
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bytes.push(self.code);
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let mut buf = Vec::with_capacity(2);
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buf.resize(2, 0);
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BigEndian::write_u16(&mut buf, if with_checksum {
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self.checksum
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} else {
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0
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});
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bytes.append(&mut buf);
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bytes.append(&mut self.message.get_bytes());
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return bytes;
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}
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/// Calculate the checksum for the packet given the provided source and destination
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/// addresses.
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pub fn calculate_checksum(&self, source: &Ipv6Addr, dest: &Ipv6Addr) -> u16 {
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// First sum the pseudo header
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let mut sum = 0u32;
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sum += ipv6_sum_words(source);
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sum += ipv6_sum_words(dest);
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// according to rfc4443: https://tools.ietf.org/html/rfc4443#section-2.3
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// the ip next header value is 58
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sum += 58u32;
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let bytes = self.get_bytes(false);
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let len = bytes.len();
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sum += len as u32;
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// Then append the message bytes as a byte buffer starting with the message
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// type field with the checksum field set to 0.
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sum += sum_big_endian_words(&bytes);
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// handle the carry
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while sum >> 16 != 0 {
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sum = (sum >> 16) + (sum & 0xFFFF);
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}
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!sum as u16
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}
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/// Fill the checksum for the packet using the given source and destination
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/// addresses.
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pub fn with_checksum(mut self, source: &Ipv6Addr, dest: &Ipv6Addr) -> Self {
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self.checksum = self.calculate_checksum(source, dest);
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self
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}
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/// Construct a packet for Destination Unreachable messages.
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pub fn with_unreachable(code: u8, packet: Vec<u8>) -> Result<Self, Icmpv6PacketBuildError> {
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if code > 6 {
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return Err(Icmpv6PacketBuildError::InvalidCode(code));
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}
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Ok(Self {
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typ: 1,
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code: code,
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checksum: 0,
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// TODO(jwall): Should we enforce that the packet isn't too big?
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// It is not supposed to be larger than the minimum IPv6 MTU
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message: Unreachable{
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_unused: 0,
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invoking_packet: packet,
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},
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})
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}
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/// Construct a packet for Packet Too Big messages.
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pub fn with_packet_too_big(mtu: u32, packet: Vec<u8>) -> Result<Self, Icmpv6PacketBuildError> {
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Ok(Self{
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typ: 2,
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code: 0,
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checksum: 0,
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// TODO(jwall): Should we enforce that the packet isn't too big?
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// It is not supposed to be larger than the minimum IPv6 MTU
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message: PacketTooBig{
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mtu: mtu,
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invoking_packet: packet,
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},
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})
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}
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/// Construct a packet for Time Exceeded messages.
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pub fn with_time_exceeded(code: u8, packet: Vec<u8>) -> Result<Self, Icmpv6PacketBuildError> {
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if code > 1 {
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return Err(Icmpv6PacketBuildError::InvalidCode(code));
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}
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Ok(Self{
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typ: 3,
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code: code,
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checksum: 0,
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// TODO(jwall): Should we enforce that the packet isn't too big?
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// It is not supposed to be larger than the minimum IPv6 MTU
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message: TimeExceeded{
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_unused: 0,
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invoking_packet: packet,
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},
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})
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}
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/// Construct a packet for Parameter Problem messages.
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pub fn with_parameter_problem(code: u8, pointer: u32, packet: Vec<u8>) -> Result<Self, Icmpv6PacketBuildError> {
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if code > 1 {
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return Err(Icmpv6PacketBuildError::InvalidCode(code));
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}
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Ok(Self {
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typ: 4,
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code: code,
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checksum: 0,
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message: ParameterProblem{
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pointer: pointer,
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invoking_packet: packet,
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}
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})
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}
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/// Construct a packet for Echo Request messages.
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pub fn with_echo_request(identifier: u16, sequence: u16, payload: Vec<u8>) -> Result<Self, Icmpv6PacketBuildError> {
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Ok(Self {
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typ: 4,
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code: 0,
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checksum: 0,
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message: EchoRequest{
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identifier: identifier,
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sequence: sequence,
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payload: payload,
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}
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})
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}
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/// Construct a packet for Echo Reply messages.
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pub fn with_echo_reply(identifier: u16, sequence: u16, payload: Vec<u8>) -> Result<Self, Icmpv6PacketBuildError> {
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Ok(Self {
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typ: 4,
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code: 0,
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checksum: 0,
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message: EchoReply{
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identifier: identifier,
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sequence: sequence,
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payload: payload,
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}
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})
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}
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}
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pub enum Icmpv6PacketBuildError {
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InvalidCode(u8),
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} |