packet_formats/
error.rs

1// Copyright 2018 The Fuchsia 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//! Custom error types for the packet formats.
6
7use core::convert::Infallible as Never;
8
9use crate::icmp::Icmpv6ParameterProblemCode;
10use net_types::MulticastAddress;
11use net_types::ip::{IpAddress, Ipv6Addr};
12use packet::records::TooFewRecordsErr;
13use packet::records::options::OptionParseErr;
14use thiserror::Error;
15
16/// Result returned from packet parsing functions.
17pub type ParseResult<T> = core::result::Result<T, ParseError>;
18
19/// Results returned from IP packet parsing functions in the netstack.
20pub type IpParseResult<I, T> = core::result::Result<T, <I as crate::ip::IpExt>::PacketParseError>;
21
22/// Error type for packet parsing.
23#[derive(Copy, Clone, Error, Debug, PartialEq)]
24pub enum ParseError {
25    /// Operation is not supported.
26    #[error("Operation is not supported")]
27    NotSupported,
28    /// Operation is not expected in this context.
29    #[error("Operation is not expected in this context")]
30    NotExpected,
31    /// Checksum is invalid.
32    #[error("Invalid checksum")]
33    Checksum,
34    /// Packet is not formatted properly.
35    #[error("Packet is not formatted properly")]
36    Format,
37}
38
39impl From<Never> for ParseError {
40    fn from(err: Never) -> ParseError {
41        match err {}
42    }
43}
44
45impl From<TooFewRecordsErr> for ParseError {
46    fn from(TooFewRecordsErr: TooFewRecordsErr) -> ParseError {
47        ParseError::Format
48    }
49}
50
51impl From<OptionParseErr> for ParseError {
52    fn from(OptionParseErr: OptionParseErr) -> ParseError {
53        ParseError::Format
54    }
55}
56
57/// Action to take when an IP node fails to parse a received IP packet.
58///
59/// These actions are taken from [RFC 8200 section 4.2]. Although these actions
60/// are defined by an IPv6 RFC, IPv4 nodes that fail to parse a received packet
61/// will take similar actions.
62///
63/// [RFC 8200 section 4.2]: https://tools.ietf.org/html/rfc8200#section-4.2
64#[derive(Copy, Clone, Debug, PartialEq)]
65pub enum IpParseErrorAction {
66    /// Discard the packet and do nothing further.
67    DiscardPacket,
68
69    /// Discard the packet and send an ICMP response.
70    DiscardPacketSendIcmp,
71
72    /// Discard the packet and send an ICMP response if the packet's
73    /// destination address was not a multicast address.
74    DiscardPacketSendIcmpNoMulticast,
75}
76
77impl IpParseErrorAction {
78    /// Determines whether or not an ICMP message should be sent.
79    ///
80    /// Returns `true` if the caller should send an ICMP response. The caller should
81    /// send an ICMP response if an action is set to `DiscardPacketSendIcmp`, or
82    /// if an action is set to `DiscardPacketSendIcmpNoMulticast` and `dst_addr`
83    /// (the destination address of the original packet that lead to a parsing
84    /// error) is not a multicast address.
85    pub fn should_send_icmp<A: IpAddress>(&self, dst_addr: &A) -> bool {
86        match *self {
87            IpParseErrorAction::DiscardPacket => false,
88            IpParseErrorAction::DiscardPacketSendIcmp => true,
89            IpParseErrorAction::DiscardPacketSendIcmpNoMulticast => !dst_addr.is_multicast(),
90        }
91    }
92
93    /// Determines whether or not an ICMP message should be sent even if the original
94    /// packet's destination address is a multicast.
95    ///
96    /// Per [RFC 1122 section 3.2.2] and [RFC 4443 section 2.4], ICMP messages MUST NOT
97    /// be sent in response to packets destined to a multicast or broadcast address.
98    /// However, RFC 4443 section 2.4 includes an exception to this rule if certain
99    /// criteria are met when parsing IPv6 extension header options.
100    /// `should_send_icmp_to_multicast` returns `true` if the criteria are met.
101    /// See RFC 4443 section 2.4 for more details about the exception.
102    ///
103    /// [RFC 1122 section 3.2.2]: https://tools.ietf.org/html/rfc1122#section-3.2.2
104    /// [RFC 4443 section 2.4]: https://tools.ietf.org/html/rfc4443#section-2.4
105    pub fn should_send_icmp_to_multicast(&self) -> bool {
106        match *self {
107            IpParseErrorAction::DiscardPacketSendIcmp => true,
108            IpParseErrorAction::DiscardPacket
109            | IpParseErrorAction::DiscardPacketSendIcmpNoMulticast => false,
110        }
111    }
112}
113
114/// Error type for IP packet parsing.
115#[allow(missing_docs)]
116/// Error when parsing an IPv6 packet.
117#[derive(Debug, Error, PartialEq, Clone)]
118pub enum Ipv6ParseError {
119    #[error("Parsing Error: {error:?}")]
120    Parse {
121        #[from]
122        error: ParseError,
123    },
124    /// For errors where an ICMP Parameter Problem error needs to be sent to the
125    /// source of a packet.
126    #[error("Parameter Problem")]
127    ParameterProblem {
128        /// The packet's source IP address.
129        src_ip: Ipv6Addr,
130
131        /// The packet's destination IP address.
132        dst_ip: Ipv6Addr,
133
134        /// The ICMPv6 parameter problem code that provides more
135        /// granular information about the parameter problem encountered.
136        code: Icmpv6ParameterProblemCode,
137
138        /// The offset of the erroneous value within the IP packet.
139        pointer: u32,
140
141        /// Whether an IP node MUST send an ICMP response if [`action`]
142        /// specifies it.
143        ///
144        /// See [`action`] for more details.
145        ///
146        /// [`action`]: crate::error::Ipv6ParseError::ParameterProblem::action
147        must_send_icmp: bool,
148
149        /// The action IP nodes should take upon encountering this error.
150        ///
151        /// If [`must_send_icmp`] is `true`, IP nodes MUST send an ICMP response
152        /// if `action` specifies it. Otherwise, the node MAY choose to discard
153        /// the packet and do nothing further.
154        ///
155        /// [`must_send_icmp`]: crate::error::Ipv6ParseError::ParameterProblem::must_send_icmp
156        action: IpParseErrorAction,
157    },
158}
159
160impl From<OptionParseErr> for Ipv6ParseError {
161    fn from(error: OptionParseErr) -> Self {
162        Ipv6ParseError::Parse { error: error.into() }
163    }
164}
165
166/// Error type for an unrecognized protocol code of type `T`.
167#[derive(Debug, Eq, PartialEq)]
168pub struct UnrecognizedProtocolCode<T>(pub T);
169
170/// A not zero value for `T` was observed, but zero was expected.
171#[derive(Debug, Eq, PartialEq)]
172pub struct NotZeroError<T>(pub T);
packet_formats/error.rs

packet_formats/
error.rs
