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// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//! Custom error types for the packet formats.
use core::convert::Infallible as Never;
use net_types::ip::IpAddress;
use net_types::MulticastAddress;
use packet::records::{options::OptionParseErr, TooFewRecordsErr};
use thiserror::Error;
use crate::icmp::IcmpIpExt;
/// Results returned from parsing functions in the netstack.
pub type ParseResult<T> = core::result::Result<T, ParseError>;
/// Results returned from IP packet parsing functions in the netstack.
pub type IpParseResult<I, T> = core::result::Result<T, IpParseError<I>>;
/// Error type for packet parsing.
#[derive(Copy, Clone, Error, Debug, PartialEq)]
pub enum ParseError {
/// Operation is not supported.
#[error("Operation is not supported")]
/// Operation is not expected in this context.
#[error("Operation is not expected in this context")]
/// Checksum is invalid.
#[error("Invalid checksum")]
/// Packet is not formatted properly.
#[error("Packet is not formatted properly")]
impl From<Never> for ParseError {
fn from(err: Never) -> ParseError {
match err {}
impl From<TooFewRecordsErr> for ParseError {
fn from(TooFewRecordsErr: TooFewRecordsErr) -> ParseError {
impl From<OptionParseErr> for ParseError {
fn from(OptionParseErr: OptionParseErr) -> ParseError {
/// Action to take when an IP node fails to parse a received IP packet.
/// These actions are taken from [RFC 8200 section 4.2]. Although these actions
/// are defined by an IPv6 RFC, IPv4 nodes that fail to parse a received packet
/// will take similar actions.
/// [RFC 8200 section 4.2]:
#[derive(Copy, Clone, Debug, PartialEq)]
pub enum IpParseErrorAction {
/// Discard the packet and do nothing further.
/// Discard the packet and send an ICMP response.
/// Discard the packet and send an ICMP response if the packet's
/// destination address was not a multicast address.
impl IpParseErrorAction {
/// Determines whether or not an ICMP message should be sent.
/// Returns `true` if the caller should send an ICMP response. The caller should
/// send an ICMP response if an action is set to `DiscardPacketSendIcmp`, or
/// if an action is set to `DiscardPacketSendIcmpNoMulticast` and `dst_addr`
/// (the destination address of the original packet that lead to a parsing
/// error) is not a multicast address.
pub fn should_send_icmp<A: IpAddress>(&self, dst_addr: &A) -> bool {
match *self {
IpParseErrorAction::DiscardPacket => false,
IpParseErrorAction::DiscardPacketSendIcmp => true,
IpParseErrorAction::DiscardPacketSendIcmpNoMulticast => !dst_addr.is_multicast(),
/// Determines whether or not an ICMP message should be sent even if the original
/// packet's destination address is a multicast.
/// Per [RFC 1122 section 3.2.2] and [RFC 4443 section 2.4], ICMP messages MUST NOT
/// be sent in response to packets destined to a multicast or broadcast address.
/// However, RFC 4443 section 2.4 includes an exception to this rule if certain
/// criteria are met when parsing IPv6 extension header options.
/// `should_send_icmp_to_multicast` returns `true` if the criteria are met.
/// See RFC 4443 section 2.4 for more details about the exception.
/// [RFC 1122 section 3.2.2]:
/// [RFC 4443 section 2.4]:
pub fn should_send_icmp_to_multicast(&self) -> bool {
match *self {
IpParseErrorAction::DiscardPacketSendIcmp => true,
| IpParseErrorAction::DiscardPacketSendIcmpNoMulticast => false,
/// Error type for IP packet parsing.
#[derive(Error, Debug, PartialEq)]
pub enum IpParseError<I: IcmpIpExt> {
#[error("Parsing Error: {error:?}")]
Parse {
error: ParseError,
/// For errors where an ICMP Parameter Problem error needs to be sent to the
/// source of a packet.
#[error("Parameter Problem")]
ParameterProblem {
/// The packet's source IP address.
src_ip: I::Addr,
/// The packet's destination IP address.
dst_ip: I::Addr,
/// The ICMPv4 or ICMPv6 parameter problem code that provides more
/// granular information about the parameter problem encountered.
code: I::ParameterProblemCode,
/// The offset of the erroneous value within the IP packet.
pointer: I::ParameterProblemPointer,
/// Whether an IP node MUST send an ICMP response if [`action`]
/// specifies it.
/// See [`action`] for more details.
/// [`action`]: crate::error::IpParseError::ParameterProblem::action
must_send_icmp: bool,
/// The length of the header up to the point of the parameter problem
/// error.
header_len: I::HeaderLen,
/// The action IP nodes should take upon encountering this error.
/// If [`must_send_icmp`] is `true`, IP nodes MUST send an ICMP response
/// if `action` specifies it. Otherwise, the node MAY choose to discard
/// the packet and do nothing further.
/// If the packet was an IPv4 non-initial fragment, `action` will be
/// [`IpParseErrorAction::DiscardPacket`].
/// [`must_send_icmp`]: crate::error::IpParseError::ParameterProblem::must_send_icmp
action: IpParseErrorAction,
impl<I: IcmpIpExt> From<OptionParseErr> for IpParseError<I> {
fn from(error: OptionParseErr) -> Self {
IpParseError::Parse { error: error.into() }
/// Error type for an unrecognized protocol code of type `T`.
#[derive(Debug, Eq, PartialEq)]
pub struct UnrecognizedProtocolCode<T>(pub T);