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// Copyright 2015-2017 Benjamin Fry <benjaminfry@me.com>
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// http://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.
//! allows a DNS domain name holder to specify one or more Certification
//! Authorities (CAs) authorized to issue certificates for that domain.
//!
//! [RFC 6844, DNS Certification Authority Authorization, January 2013](https://tools.ietf.org/html/rfc6844)
//!
//! ```text
//! The Certification Authority Authorization (CAA) DNS Resource Record
//! allows a DNS domain name holder to specify one or more Certification
//! Authorities (CAs) authorized to issue certificates for that domain.
//! CAA Resource Records allow a public Certification Authority to
//! implement additional controls to reduce the risk of unintended
//! certificate mis-issue. This document defines the syntax of the CAA
//! record and rules for processing CAA records by certificate issuers.
//! ```
#![allow(clippy::use_self)]
use std::fmt;
use std::str;
#[cfg(feature = "serde-config")]
use serde::{Deserialize, Serialize};
use crate::error::*;
use crate::rr::domain::Name;
use crate::serialize::binary::*;
use url::Url;
/// The CAA RR Type
///
/// [RFC 6844, DNS Certification Authority Authorization, January 2013](https://tools.ietf.org/html/rfc6844#section-3)
///
/// ```text
/// 3. The CAA RR Type
///
/// A CAA RR consists of a flags byte and a tag-value pair referred to as
/// a property. Multiple properties MAY be associated with the same
/// domain name by publishing multiple CAA RRs at that domain name. The
/// following flag is defined:
///
/// Issuer Critical: If set to '1', indicates that the corresponding
/// property tag MUST be understood if the semantics of the CAA record
/// are to be correctly interpreted by an issuer.
///
/// Issuers MUST NOT issue certificates for a domain if the relevant
/// CAA Resource Record set contains unknown property tags that have
/// the Critical bit set.
///
/// The following property tags are defined:
///
/// issue <Issuer Domain Name> [; <name>=<value> ]* : The issue property
/// entry authorizes the holder of the domain name <Issuer Domain
/// Name> or a party acting under the explicit authority of the holder
/// of that domain name to issue certificates for the domain in which
/// the property is published.
///
/// issuewild <Issuer Domain Name> [; <name>=<value> ]* : The issuewild
/// property entry authorizes the holder of the domain name <Issuer
/// Domain Name> or a party acting under the explicit authority of the
/// holder of that domain name to issue wildcard certificates for the
/// domain in which the property is published.
///
/// iodef <URL> : Specifies a URL to which an issuer MAY report
/// certificate issue requests that are inconsistent with the issuer's
/// Certification Practices or Certificate Policy, or that a
/// Certificate Evaluator may use to report observation of a possible
/// policy violation. The Incident Object Description Exchange Format
/// (IODEF) format is used [RFC5070].
///
/// The following example is a DNS zone file (see [RFC1035]) that informs
/// CAs that certificates are not to be issued except by the holder of
/// the domain name 'ca.example.net' or an authorized agent thereof.
/// This policy applies to all subordinate domains under example.com.
///
/// $ORIGIN example.com
/// . CAA 0 issue "ca.example.net"
///
/// If the domain name holder specifies one or more iodef properties, a
/// certificate issuer MAY report invalid certificate requests to that
/// address. In the following example, the domain name holder specifies
/// that reports may be made by means of email with the IODEF data as an
/// attachment, a Web service [RFC6546], or both:
///
/// $ORIGIN example.com
/// . CAA 0 issue "ca.example.net"
/// . CAA 0 iodef "mailto:security@example.com"
/// . CAA 0 iodef "http://iodef.example.com/"
///
/// A certificate issuer MAY specify additional parameters that allow
/// customers to specify additional parameters governing certificate
/// issuance. This might be the Certificate Policy under which the
/// certificate is to be issued, the authentication process to be used
/// might be specified, or an account number specified by the CA to
/// enable these parameters to be retrieved.
///
/// For example, the CA 'ca.example.net' has requested its customer
/// 'example.com' to specify the CA's account number '230123' in each of
/// the customer's CAA records.
///
/// $ORIGIN example.com
/// . CAA 0 issue "ca.example.net; account=230123"
///
/// The syntax of additional parameters is a sequence of name-value pairs
/// as defined in Section 5.2. The semantics of such parameters is left
/// to site policy and is outside the scope of this document.
///
/// The critical flag is intended to permit future versions CAA to
/// introduce new semantics that MUST be understood for correct
/// processing of the record, preventing conforming CAs that do not
/// recognize the new semantics from issuing certificates for the
/// indicated domains.
///
/// In the following example, the property 'tbs' is flagged as critical.
/// Neither the example.net CA nor any other issuer is authorized to
/// issue under either policy unless the processing rules for the 'tbs'
/// property tag are understood.
///
/// $ORIGIN example.com
/// . CAA 0 issue "ca.example.net; policy=ev"
/// . CAA 128 tbs "Unknown"
///
/// Note that the above restrictions only apply at certificate issue.
/// Since the validity of an end entity certificate is typically a year
/// or more, it is quite possible that the CAA records published at a
/// domain will change between the time a certificate was issued and
/// validation by a relying party.
/// ```
#[cfg_attr(feature = "serde-config", derive(Deserialize, Serialize))]
#[derive(Debug, PartialEq, Eq, Hash, Clone)]
pub struct CAA {
#[doc(hidden)]
pub issuer_critical: bool,
#[doc(hidden)]
pub tag: Property,
#[doc(hidden)]
pub value: Value,
}
impl CAA {
fn issue(
issuer_critical: bool,
tag: Property,
name: Option<Name>,
options: Vec<KeyValue>,
) -> Self {
assert!(tag.is_issue() || tag.is_issuewild());
Self {
issuer_critical,
tag,
value: Value::Issuer(name, options),
}
}
/// Creates a new CAA issue record data, the tag is `issue`
///
/// # Arguments
///
/// * `issuer_critical` - indicates that the corresponding property tag MUST be understood if the semantics of the CAA record are to be correctly interpreted by an issuer
/// * `name` - authorized to issue certificates for the associated record label
/// * `options` - additional options for the issuer, e.g. 'account', etc.
pub fn new_issue(issuer_critical: bool, name: Option<Name>, options: Vec<KeyValue>) -> Self {
Self::issue(issuer_critical, Property::Issue, name, options)
}
/// Creates a new CAA issue record data, the tag is `issuewild`
///
/// # Arguments
///
/// * `issuer_critical` - indicates that the corresponding property tag MUST be understood if the semantics of the CAA record are to be correctly interpreted by an issuer
/// * `name` - authorized to issue certificates for the associated record label
/// * `options` - additional options for the issuer, e.g. 'account', etc.
pub fn new_issuewild(
issuer_critical: bool,
name: Option<Name>,
options: Vec<KeyValue>,
) -> Self {
Self::issue(issuer_critical, Property::IssueWild, name, options)
}
/// Creates a new CAA issue record data, the tag is `iodef`
///
/// # Arguments
///
/// * `issuer_critical` - indicates that the corresponding property tag MUST be understood if the semantics of the CAA record are to be correctly interpreted by an issuer
/// * `url` - Url where issuer errors should be reported
///
/// # Panics
///
/// If `value` is not `Value::Issuer`
pub fn new_iodef(issuer_critical: bool, url: Url) -> Self {
Self {
issuer_critical,
tag: Property::Iodef,
value: Value::Url(url),
}
}
/// Indicates that the corresponding property tag MUST be understood if the semantics of the CAA record are to be correctly interpreted by an issuer
pub fn issuer_critical(&self) -> bool {
self.issuer_critical
}
/// The property tag, see struct documentation
pub fn tag(&self) -> &Property {
&self.tag
}
/// a potentially associated value with the property tag, see struct documentation
pub fn value(&self) -> &Value {
&self.value
}
}
/// Specifies in what contexts this key may be trusted for use
#[cfg_attr(feature = "serde-config", derive(Deserialize, Serialize))]
#[derive(Debug, PartialEq, Eq, Hash, Clone)]
pub enum Property {
/// The issue property
/// entry authorizes the holder of the domain name <Issuer Domain
/// Name> or a party acting under the explicit authority of the holder
/// of that domain name to issue certificates for the domain in which
/// the property is published.
Issue,
/// The issuewild
/// property entry authorizes the holder of the domain name <Issuer
/// Domain Name> or a party acting under the explicit authority of the
/// holder of that domain name to issue wildcard certificates for the
/// domain in which the property is published.
IssueWild,
/// Specifies a URL to which an issuer MAY report
/// certificate issue requests that are inconsistent with the issuer's
/// Certification Practices or Certificate Policy, or that a
/// Certificate Evaluator may use to report observation of a possible
/// policy violation. The Incident Object Description Exchange Format
/// (IODEF) format is used [RFC5070](https://tools.ietf.org/html/rfc5070).
Iodef,
/// Unknown format to Trust-DNS
Unknown(String),
}
impl Property {
/// Convert to string form
pub fn as_str(&self) -> &str {
match *self {
Self::Issue => "issue",
Self::IssueWild => "issuewild",
Self::Iodef => "iodef",
Self::Unknown(ref property) => property,
}
}
/// true if the property is `issue`
pub fn is_issue(&self) -> bool {
matches!(*self, Self::Issue)
}
/// true if the property is `issueworld`
pub fn is_issuewild(&self) -> bool {
matches!(*self, Self::IssueWild)
}
/// true if the property is `iodef`
pub fn is_iodef(&self) -> bool {
matches!(*self, Self::Iodef)
}
/// true if the property is not known to Trust-DNS
pub fn is_unknown(&self) -> bool {
matches!(*self, Self::Unknown(_))
}
}
impl From<String> for Property {
fn from(tag: String) -> Self {
// RFC6488 section 5.1 states that "Matching of tag values is case
// insensitive."
let lower = tag.to_ascii_lowercase();
match &lower as &str {
"issue" => return Self::Issue,
"issuewild" => return Self::IssueWild,
"iodef" => return Self::Iodef,
&_ => (),
}
Self::Unknown(tag)
}
}
/// Potential values.
///
/// These are based off the Tag field:
///
/// `Issue` and `IssueWild` => `Issuer`,
/// `Iodef` => `Url`,
/// `Unknown` => `Unknown`,
#[cfg_attr(feature = "serde-config", derive(Deserialize, Serialize))]
#[derive(Debug, PartialEq, Eq, Hash, Clone)]
pub enum Value {
/// Issuer authorized to issue certs for this zone, and any associated parameters
Issuer(Option<Name>, Vec<KeyValue>),
/// Url to which to send CA errors
Url(Url),
/// Unrecognized tag and value by Trust-DNS
Unknown(Vec<u8>),
}
impl Value {
/// true if this is an `Issuer`
pub fn is_issuer(&self) -> bool {
matches!(*self, Value::Issuer(..))
}
/// true if this is a `Url`
pub fn is_url(&self) -> bool {
matches!(*self, Value::Url(..))
}
/// true if this is an `Unknown`
pub fn is_unknown(&self) -> bool {
matches!(*self, Value::Unknown(..))
}
}
fn read_value(
tag: &Property,
decoder: &mut BinDecoder<'_>,
value_len: Restrict<u16>,
) -> ProtoResult<Value> {
let value_len = value_len.map(|u| u as usize).unverified(/*used purely as length safely*/);
match *tag {
Property::Issue | Property::IssueWild => {
let slice = decoder.read_slice(value_len)?.unverified(/*read_issuer verified as safe*/);
let value = read_issuer(slice)?;
Ok(Value::Issuer(value.0, value.1))
}
Property::Iodef => {
let url = decoder.read_slice(value_len)?.unverified(/*read_iodef verified as safe*/);
let url = read_iodef(url)?;
Ok(Value::Url(url))
}
Property::Unknown(_) => Ok(Value::Unknown(
decoder.read_vec(value_len)?.unverified(/*unknown will fail in usage*/),
)),
}
}
fn emit_value(encoder: &mut BinEncoder<'_>, value: &Value) -> ProtoResult<()> {
match *value {
Value::Issuer(ref name, ref key_values) => {
// output the name
if let Some(ref name) = *name {
let name = name.to_string();
encoder.emit_vec(name.as_bytes())?;
}
// if there was no name, then we just output ';'
if name.is_none() && key_values.is_empty() {
return encoder.emit(b';');
}
for key_value in key_values {
encoder.emit(b';')?;
encoder.emit(b' ')?;
encoder.emit_vec(key_value.key.as_bytes())?;
encoder.emit(b'=')?;
encoder.emit_vec(key_value.value.as_bytes())?;
}
Ok(())
}
Value::Url(ref url) => {
let url = url.as_str();
let bytes = url.as_bytes();
encoder.emit_vec(bytes)
}
Value::Unknown(ref data) => encoder.emit_vec(data),
}
}
enum ParseNameKeyPairState {
BeforeKey(Vec<KeyValue>),
Key {
first_char: bool,
key: String,
key_values: Vec<KeyValue>,
},
Value {
key: String,
value: String,
key_values: Vec<KeyValue>,
},
}
/// Reads the issuer field according to the spec
///
/// [RFC 6844, DNS Certification Authority Authorization, January 2013](https://tools.ietf.org/html/rfc6844#section-5.2)
///
/// ```text
/// 5.2. CAA issue Property
///
/// The issue property tag is used to request that certificate issuers
/// perform CAA issue restriction processing for the domain and to grant
/// authorization to specific certificate issuers.
///
/// The CAA issue property value has the following sub-syntax (specified
/// in ABNF as per [RFC5234]).
///
/// issuevalue = space [domain] space [";" *(space parameter) space]
///
/// domain = label *("." label)
/// label = (ALPHA / DIGIT) *( *("-") (ALPHA / DIGIT))
///
/// space = *(SP / HTAB)
///
/// parameter = tag "=" value
///
/// tag = 1*(ALPHA / DIGIT)
///
/// value = *VCHAR
///
/// For consistency with other aspects of DNS administration, domain name
/// values are specified in letter-digit-hyphen Label (LDH-Label) form.
///
/// A CAA record with an issue parameter tag that does not specify a
/// domain name is a request that certificate issuers perform CAA issue
/// restriction processing for the corresponding domain without granting
/// authorization to any certificate issuer.
///
/// This form of issue restriction would be appropriate to specify that
/// no certificates are to be issued for the domain in question.
///
/// For example, the following CAA record set requests that no
/// certificates be issued for the domain 'nocerts.example.com' by any
/// certificate issuer.
///
/// nocerts.example.com CAA 0 issue ";"
///
/// A CAA record with an issue parameter tag that specifies a domain name
/// is a request that certificate issuers perform CAA issue restriction
/// processing for the corresponding domain and grants authorization to
/// the certificate issuer specified by the domain name.
///
/// For example, the following CAA record set requests that no
/// certificates be issued for the domain 'certs.example.com' by any
/// certificate issuer other than the example.net certificate issuer.
///
/// certs.example.com CAA 0 issue "example.net"
///
/// CAA authorizations are additive; thus, the result of specifying both
/// the empty issuer and a specified issuer is the same as specifying
/// just the specified issuer alone.
///
/// An issuer MAY choose to specify issuer-parameters that further
/// constrain the issue of certificates by that issuer, for example,
/// specifying that certificates are to be subject to specific validation
/// polices, billed to certain accounts, or issued under specific trust
/// anchors.
///
/// The semantics of issuer-parameters are determined by the issuer
/// alone.
/// ```
///
/// Updated parsing rules:
///
/// [RFC 6844bis, CAA Resource Record, May 2018](https://tools.ietf.org/html/draft-ietf-lamps-rfc6844bis-00)
/// [RFC 6844, CAA Record Extensions, May 2018](https://tools.ietf.org/html/draft-ietf-acme-caa-04)
///
/// This explicitly allows `-` in key names, diverging from the original RFC. To support this, key names will
/// allow `-` as non-starting characters. Additionally, this significantly relaxes the characters allowed in the value
/// to allow URL like characters (it does not validate URL syntax).
pub fn read_issuer(bytes: &[u8]) -> ProtoResult<(Option<Name>, Vec<KeyValue>)> {
let mut byte_iter = bytes.iter();
// we want to reuse the name parsing rules
let name: Option<Name> = {
let take_name = byte_iter.by_ref().take_while(|ch| char::from(**ch) != ';');
let name_str = take_name.cloned().collect::<Vec<u8>>();
if !name_str.is_empty() {
let name_str = str::from_utf8(&name_str)?;
Some(Name::parse(name_str, None)?)
} else {
None
}
};
// initial state is looking for a key ';' is valid...
let mut state = ParseNameKeyPairState::BeforeKey(vec![]);
// run the state machine through all remaining data, collecting all key/value pairs.
for ch in byte_iter {
match state {
// Name was already successfully parsed, otherwise we couldn't get here.
ParseNameKeyPairState::BeforeKey(key_values) => {
match char::from(*ch) {
// gobble ';', ' ', and tab
';' | ' ' | '\u{0009}' => state = ParseNameKeyPairState::BeforeKey(key_values),
ch if ch.is_alphanumeric() && ch != '=' => {
// We found the beginning of a new Key
let mut key = String::new();
key.push(ch);
state = ParseNameKeyPairState::Key {
first_char: true,
key,
key_values,
}
}
ch => return Err(format!("bad character in CAA issuer key: {}", ch).into()),
}
}
ParseNameKeyPairState::Key {
first_char,
mut key,
key_values,
} => {
match char::from(*ch) {
// transition to value
'=' => {
let value = String::new();
state = ParseNameKeyPairState::Value {
key,
value,
key_values,
}
}
// push onto the existing key
ch if (ch.is_alphanumeric() || (!first_char && ch == '-'))
&& ch != '='
&& ch != ';' =>
{
key.push(ch);
state = ParseNameKeyPairState::Key {
first_char: false,
key,
key_values,
}
}
ch => return Err(format!("bad character in CAA issuer key: {}", ch).into()),
}
}
ParseNameKeyPairState::Value {
key,
mut value,
mut key_values,
} => {
match char::from(*ch) {
// transition back to find another pair
';' => {
key_values.push(KeyValue { key, value });
state = ParseNameKeyPairState::BeforeKey(key_values);
}
// push onto the existing key
ch if !ch.is_control() && !ch.is_whitespace() => {
value.push(ch);
state = ParseNameKeyPairState::Value {
key,
value,
key_values,
}
}
ch => return Err(format!("bad character in CAA issuer value: '{}'", ch).into()),
}
}
}
}
// valid final states are BeforeKey, where there was a final ';' but nothing followed it.
// Value, where we collected the final chars of the value, but no more data
let key_values = match state {
ParseNameKeyPairState::BeforeKey(key_values) => key_values,
ParseNameKeyPairState::Value {
key,
value,
mut key_values,
} => {
key_values.push(KeyValue { key, value });
key_values
}
ParseNameKeyPairState::Key { key, .. } => {
return Err(format!("key missing value: {}", key).into());
}
};
Ok((name, key_values))
}
/// Incident Object Description Exchange Format
///
/// [RFC 6844, DNS Certification Authority Authorization, January 2013](https://tools.ietf.org/html/rfc6844#section-5.4)
///
/// ```text
/// 5.4. CAA iodef Property
///
/// The iodef property specifies a means of reporting certificate issue
/// requests or cases of certificate issue for the corresponding domain
/// that violate the security policy of the issuer or the domain name
/// holder.
///
/// The Incident Object Description Exchange Format (IODEF) [RFC5070] is
/// used to present the incident report in machine-readable form.
///
/// The iodef property takes a URL as its parameter. The URL scheme type
/// determines the method used for reporting:
///
/// mailto: The IODEF incident report is reported as a MIME email
/// attachment to an SMTP email that is submitted to the mail address
/// specified. The mail message sent SHOULD contain a brief text
/// message to alert the recipient to the nature of the attachment.
///
/// http or https: The IODEF report is submitted as a Web service
/// request to the HTTP address specified using the protocol specified
/// in [RFC6546].
/// ```
pub fn read_iodef(url: &[u8]) -> ProtoResult<Url> {
let url = str::from_utf8(url)?;
let url = Url::parse(url)?;
Ok(url)
}
/// Issuer key and value pairs.
///
/// See [RFC 6844, DNS Certification Authority Authorization, January 2013](https://tools.ietf.org/html/rfc6844#section-5.2)
/// for more explanation.
#[cfg_attr(feature = "serde-config", derive(Deserialize, Serialize))]
#[derive(Debug, PartialEq, Eq, Hash, Clone)]
pub struct KeyValue {
key: String,
value: String,
}
impl KeyValue {
/// Construct a new KeyValue pair
pub fn new<K: Into<String>, V: Into<String>>(key: K, value: V) -> Self {
Self {
key: key.into(),
value: value.into(),
}
}
/// Gets a reference to the key of the pair.
pub fn key(&self) -> &str {
&self.key
}
/// Gets a reference to the value of the pair.
pub fn value(&self) -> &str {
&self.value
}
}
/// Read the binary CAA format
///
/// [RFC 6844, DNS Certification Authority Authorization, January 2013](https://tools.ietf.org/html/rfc6844#section-5.1)
///
/// ```text
/// 5.1. Syntax
///
/// A CAA RR contains a single property entry consisting of a tag-value
/// pair. Each tag represents a property of the CAA record. The value
/// of a CAA property is that specified in the corresponding value field.
///
/// A domain name MAY have multiple CAA RRs associated with it and a
/// given property MAY be specified more than once.
///
/// The CAA data field contains one property entry. A property entry
/// consists of the following data fields:
///
/// +0-1-2-3-4-5-6-7-|0-1-2-3-4-5-6-7-|
/// | Flags | Tag Length = n |
/// +----------------+----------------+...+---------------+
/// | Tag char 0 | Tag char 1 |...| Tag char n-1 |
/// +----------------+----------------+...+---------------+
/// +----------------+----------------+.....+----------------+
/// | Value byte 0 | Value byte 1 |.....| Value byte m-1 |
/// +----------------+----------------+.....+----------------+
///
/// Where n is the length specified in the Tag length field and m is the
/// remaining octets in the Value field (m = d - n - 2) where d is the
/// length of the RDATA section.
///
/// The data fields are defined as follows:
///
/// Flags: One octet containing the following fields:
///
/// Bit 0, Issuer Critical Flag: If the value is set to '1', the
/// critical flag is asserted and the property MUST be understood
/// if the CAA record is to be correctly processed by a certificate
/// issuer.
///
/// A Certification Authority MUST NOT issue certificates for any
/// Domain that contains a CAA critical property for an unknown or
/// unsupported property tag that for which the issuer critical
/// flag is set.
///
/// Note that according to the conventions set out in [RFC1035], bit 0
/// is the Most Significant Bit and bit 7 is the Least Significant
/// Bit. Thus, the Flags value 1 means that bit 7 is set while a value
/// of 128 means that bit 0 is set according to this convention.
///
/// All other bit positions are reserved for future use.
///
/// To ensure compatibility with future extensions to CAA, DNS records
/// compliant with this version of the CAA specification MUST clear
/// (set to "0") all reserved flags bits. Applications that interpret
/// CAA records MUST ignore the value of all reserved flag bits.
///
/// Tag Length: A single octet containing an unsigned integer specifying
/// the tag length in octets. The tag length MUST be at least 1 and
/// SHOULD be no more than 15.
///
/// Tag: The property identifier, a sequence of US-ASCII characters.
///
/// Tag values MAY contain US-ASCII characters 'a' through 'z', 'A'
/// through 'Z', and the numbers 0 through 9. Tag values SHOULD NOT
/// contain any other characters. Matching of tag values is case
/// insensitive.
///
/// Tag values submitted for registration by IANA MUST NOT contain any
/// characters other than the (lowercase) US-ASCII characters 'a'
/// through 'z' and the numbers 0 through 9.
///
/// Value: A sequence of octets representing the property value.
/// Property values are encoded as binary values and MAY employ sub-
/// formats.
///
/// The length of the value field is specified implicitly as the
/// remaining length of the enclosing Resource Record data field.
/// ```
pub fn read(decoder: &mut BinDecoder<'_>, rdata_length: Restrict<u16>) -> ProtoResult<CAA> {
// the spec declares that other flags should be ignored for future compatibility...
let issuer_critical: bool =
decoder.read_u8()?.unverified(/*used as bitfield*/) & 0b1000_0000 != 0;
let tag_len = decoder.read_u8()?;
let value_len: Restrict<u16> = rdata_length
.checked_sub(u16::from(tag_len.unverified(/*safe usage here*/)))
.checked_sub(2)
.map_err(|_| ProtoError::from("CAA tag character(s) out of bounds"))?;
let tag = read_tag(decoder, tag_len)?;
let tag = Property::from(tag);
let value = read_value(&tag, decoder, value_len)?;
Ok(CAA {
issuer_critical,
tag,
value,
})
}
// TODO: change this to return &str
fn read_tag(decoder: &mut BinDecoder<'_>, len: Restrict<u8>) -> ProtoResult<String> {
let len = len
.map(|len| len as usize)
.verify_unwrap(|len| *len > 0 && *len <= 15)
.map_err(|_| ProtoError::from("CAA tag length out of bounds, 1-15"))?;
let mut tag = String::with_capacity(len);
for _ in 0..len {
let ch = decoder
.pop()?
.map(char::from)
.verify_unwrap(|ch| matches!(ch, 'a'..='z' | 'A'..='Z' | '0'..='9'))
.map_err(|_| ProtoError::from("CAA tag character(s) out of bounds"))?;
tag.push(ch);
}
Ok(tag)
}
/// writes out the tag in binary form to the buffer, returning the number of bytes written
fn emit_tag(buf: &mut [u8], tag: &Property) -> ProtoResult<u8> {
let property = tag.as_str();
let property = property.as_bytes();
let len = property.len();
if len > ::std::u8::MAX as usize {
return Err(format!("CAA property too long: {}", len).into());
}
if buf.len() < len {
return Err(format!(
"insufficient capacity in CAA buffer: {} for tag: {}",
buf.len(),
len
)
.into());
}
// copy into the buffer
let buf = &mut buf[0..len];
buf.copy_from_slice(property);
Ok(len as u8)
}
/// Write the RData from the given Decoder
pub fn emit(encoder: &mut BinEncoder<'_>, caa: &CAA) -> ProtoResult<()> {
let mut flags = 0_u8;
if caa.issuer_critical {
flags |= 0b1000_0000;
}
encoder.emit(flags)?;
// TODO: it might be interesting to use the new place semantics here to output all the data, then place the length back to the beginning...
let mut tag_buf = [0_u8; ::std::u8::MAX as usize];
let len = emit_tag(&mut tag_buf, &caa.tag)?;
// now write to the encoder
encoder.emit(len)?;
encoder.emit_vec(&tag_buf[0..len as usize])?;
emit_value(encoder, &caa.value)?;
Ok(())
}
impl fmt::Display for Property {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
let s = match self {
Self::Issue => "issue",
Self::IssueWild => "issuewild",
Self::Iodef => "iodef",
Self::Unknown(s) => s,
};
f.write_str(s)
}
}
impl fmt::Display for Value {
// https://datatracker.ietf.org/doc/html/rfc6844#section-5.1.1
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
f.write_str("\"")?;
match self {
Value::Issuer(name, values) => {
match name {
Some(name) => write!(f, "{}", name)?,
None => write!(f, ";")?,
}
if let Some(value) = values.first() {
write!(f, " {}", value)?;
for value in &values[1..] {
write!(f, "; {}", value)?;
}
}
}
Value::Url(url) => write!(f, "{}", url)?,
Value::Unknown(v) => write!(f, "{:?}", v)?,
}
f.write_str("\"")
}
}
impl fmt::Display for KeyValue {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
f.write_str(&self.key)?;
if !self.value.is_empty() {
write!(f, "={}", self.value)?;
}
Ok(())
}
}
// FIXME: this needs to be verified to be correct, add tests...
impl fmt::Display for CAA {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
let critical = if self.issuer_critical { "1" } else { "0" };
write!(
f,
"{critical} {tag} {value}",
critical = critical,
tag = self.tag,
value = self.value
)
}
}
#[cfg(test)]
mod tests {
#![allow(clippy::dbg_macro, clippy::print_stdout)]
use super::*;
use std::str;
#[test]
fn test_read_tag() {
let ok_under15 = b"abcxyzABCXYZ019";
let mut decoder = BinDecoder::new(ok_under15);
let read = read_tag(&mut decoder, Restrict::new(ok_under15.len() as u8))
.expect("failed to read tag");
assert_eq!(str::from_utf8(ok_under15).unwrap(), read);
}
#[test]
fn test_bad_tag() {
let bad_under15 = b"-";
let mut decoder = BinDecoder::new(bad_under15);
assert!(read_tag(&mut decoder, Restrict::new(bad_under15.len() as u8)).is_err());
}
#[test]
fn test_too_short_tag() {
let too_short = b"";
let mut decoder = BinDecoder::new(too_short);
assert!(read_tag(&mut decoder, Restrict::new(too_short.len() as u8)).is_err());
}
#[test]
fn test_too_long_tag() {
let too_long = b"0123456789abcdef";
let mut decoder = BinDecoder::new(too_long);
assert!(read_tag(&mut decoder, Restrict::new(too_long.len() as u8)).is_err());
}
#[test]
fn test_from_str_property() {
assert_eq!(Property::from("Issue".to_string()), Property::Issue);
assert_eq!(Property::from("issueWild".to_string()), Property::IssueWild);
assert_eq!(Property::from("iodef".to_string()), Property::Iodef);
assert_eq!(
Property::from("unknown".to_string()),
Property::Unknown("unknown".to_string())
);
}
#[test]
fn test_read_issuer() {
// (Option<Name>, Vec<KeyValue>)
assert_eq!(
read_issuer(b"ca.example.net; account=230123").unwrap(),
(
Some(Name::parse("ca.example.net", None).unwrap()),
vec![KeyValue {
key: "account".to_string(),
value: "230123".to_string(),
}],
)
);
assert_eq!(
read_issuer(b"ca.example.net").unwrap(),
(Some(Name::parse("ca.example.net", None,).unwrap(),), vec![],)
);
assert_eq!(
read_issuer(b"ca.example.net; policy=ev").unwrap(),
(
Some(Name::parse("ca.example.net", None).unwrap(),),
vec![KeyValue {
key: "policy".to_string(),
value: "ev".to_string(),
}],
)
);
assert_eq!(
read_issuer(b"ca.example.net; account=230123; policy=ev").unwrap(),
(
Some(Name::parse("ca.example.net", None).unwrap(),),
vec![
KeyValue {
key: "account".to_string(),
value: "230123".to_string(),
},
KeyValue {
key: "policy".to_string(),
value: "ev".to_string(),
},
],
)
);
assert_eq!(
read_issuer(b"example.net; account-uri=https://example.net/account/1234; validation-methods=dns-01").unwrap(),
(
Some(Name::parse("example.net", None).unwrap(),),
vec![
KeyValue {
key: "account-uri".to_string(),
value: "https://example.net/account/1234".to_string(),
},
KeyValue {
key: "validation-methods".to_string(),
value: "dns-01".to_string(),
},
],
)
);
assert_eq!(read_issuer(b";").unwrap(), (None, vec![]));
}
#[test]
fn test_read_iodef() {
assert_eq!(
read_iodef(b"mailto:security@example.com").unwrap(),
Url::parse("mailto:security@example.com").unwrap()
);
assert_eq!(
read_iodef(b"http://iodef.example.com/").unwrap(),
Url::parse("http://iodef.example.com/").unwrap()
);
}
fn test_encode_decode(rdata: CAA) {
let mut bytes = Vec::new();
let mut encoder: BinEncoder<'_> = BinEncoder::new(&mut bytes);
emit(&mut encoder, &rdata).expect("failed to emit caa");
let bytes = encoder.into_bytes();
println!("bytes: {:?}", bytes);
let mut decoder: BinDecoder<'_> = BinDecoder::new(bytes);
let read_rdata =
read(&mut decoder, Restrict::new(bytes.len() as u16)).expect("failed to read back");
assert_eq!(rdata, read_rdata);
}
#[test]
fn test_encode_decode_issue() {
test_encode_decode(CAA::new_issue(true, None, vec![]));
test_encode_decode(CAA::new_issue(
true,
Some(Name::parse("example.com", None).unwrap()),
vec![],
));
test_encode_decode(CAA::new_issue(
true,
Some(Name::parse("example.com", None).unwrap()),
vec![KeyValue::new("key", "value")],
));
// technically the this parser supports this case, though it's not clear it's something the spec allows for
test_encode_decode(CAA::new_issue(
true,
None,
vec![KeyValue::new("key", "value")],
));
// test fqdn
test_encode_decode(CAA::new_issue(
true,
Some(Name::parse("example.com.", None).unwrap()),
vec![],
));
}
#[test]
fn test_encode_decode_issuewild() {
test_encode_decode(CAA::new_issuewild(false, None, vec![]));
// other variants handled in test_encode_decode_issue
}
#[test]
fn test_encode_decode_iodef() {
test_encode_decode(CAA::new_iodef(
true,
Url::parse("http://www.example.com").unwrap(),
));
test_encode_decode(CAA::new_iodef(
false,
Url::parse("mailto:root@example.com").unwrap(),
));
}
fn test_encode(rdata: CAA, encoded: &[u8]) {
let mut bytes = Vec::new();
let mut encoder: BinEncoder<'_> = BinEncoder::new(&mut bytes);
emit(&mut encoder, &rdata).expect("failed to emit caa");
let bytes = encoder.into_bytes();
assert_eq!(bytes as &[u8], encoded);
}
#[test]
fn test_encode_non_fqdn() {
let name_bytes: &[u8] = b"issueexample.com";
let header: &[u8] = &[128, 5];
let encoded: Vec<u8> = header.iter().chain(name_bytes.iter()).cloned().collect();
test_encode(
CAA::new_issue(
true,
Some(Name::parse("example.com", None).unwrap()),
vec![],
),
&encoded,
);
}
#[test]
fn test_encode_fqdn() {
let name_bytes: &[u8] = b"issueexample.com.";
let header: [u8; 2] = [128, 5];
let encoded: Vec<u8> = header.iter().chain(name_bytes.iter()).cloned().collect();
test_encode(
CAA::new_issue(
true,
Some(Name::parse("example.com.", None).unwrap()),
vec![],
),
&encoded,
);
}
#[test]
fn test_tostring() {
let deny = CAA::new_issue(false, None, vec![]);
assert_eq!(deny.to_string(), "0 issue \";\"");
let empty_options = CAA::new_issue(
false,
Some(Name::parse("example.com", None).unwrap()),
vec![],
);
assert_eq!(empty_options.to_string(), "0 issue \"example.com\"");
let one_option = CAA::new_issue(
false,
Some(Name::parse("example.com", None).unwrap()),
vec![KeyValue::new("one", "1")],
);
assert_eq!(one_option.to_string(), "0 issue \"example.com one=1\"");
let two_options = CAA::new_issue(
false,
Some(Name::parse("example.com", None).unwrap()),
vec![KeyValue::new("one", "1"), KeyValue::new("two", "2")],
);
assert_eq!(
two_options.to_string(),
"0 issue \"example.com one=1; two=2\""
);
}
}