dnssec_prover/
ser.rs

1//! Logic to read and write resource record (streams)
2
3use alloc::vec::Vec;
4use alloc::string::String;
5
6use crate::rr::*;
7use crate::query::QueryBuf;
8
9pub(crate) fn read_u8(inp: &mut &[u8]) -> Result<u8, ()> {
10	let res = *inp.first().ok_or(())?;
11	*inp = &inp[1..];
12	Ok(res)
13}
14pub(crate) fn read_u16(inp: &mut &[u8]) -> Result<u16, ()> {
15	if inp.len() < 2 { return Err(()); }
16	let mut bytes = [0; 2];
17	bytes.copy_from_slice(&inp[..2]);
18	*inp = &inp[2..];
19	Ok(u16::from_be_bytes(bytes))
20}
21pub(crate) fn read_u32(inp: &mut &[u8]) -> Result<u32, ()> {
22	if inp.len() < 4 { return Err(()); }
23	let mut bytes = [0; 4];
24	bytes.copy_from_slice(&inp[..4]);
25	*inp = &inp[4..];
26	Ok(u32::from_be_bytes(bytes))
27}
28
29pub(crate) fn read_u8_len_prefixed_bytes(inp: &mut &[u8]) -> Result<Vec<u8>, ()> {
30	let len = *inp.first().ok_or(())?;
31	*inp = &inp[1..];
32	if inp.len() < len.into() { return Err(()); }
33	let mut res = Vec::with_capacity(len.into());
34	res.extend_from_slice(&inp[..len.into()]);
35	*inp = &inp[len.into()..];
36	Ok(res)
37}
38
39pub(crate) fn write_nsec_types_bitmap<W: Writer>(out: &mut W, types: &[u8; 8192]) {
40	for (idx, flags) in types.chunks(32).enumerate() {
41		debug_assert_eq!(flags.len(), 32);
42		if flags != [0; 32] {
43			let last_nonzero_idx = flags.iter().rposition(|flag| *flag != 0)
44				.unwrap_or_else(|| { debug_assert!(false); 0 });
45			out.write(&(idx as u8).to_be_bytes());
46			out.write(&(last_nonzero_idx as u8 + 1).to_be_bytes());
47			out.write(&flags[..last_nonzero_idx + 1]);
48		}
49	}
50}
51pub(crate) fn nsec_types_bitmap_len(types: &[u8; 8192]) -> u16 {
52	let mut total_len = 0;
53	for flags in types.chunks(32) {
54		debug_assert_eq!(flags.len(), 32);
55		if flags != [0; 32] {
56			total_len += 3 + flags.iter().rposition(|flag| *flag != 0)
57				.unwrap_or_else(|| { debug_assert!(false); 0 }) as u16;
58		}
59	}
60	total_len
61}
62
63pub(crate) fn read_nsec_types_bitmap(inp: &mut &[u8]) -> Result<[u8; 8192], ()> {
64	let mut res = [0; 8192];
65	while !inp.is_empty() {
66		let block = *inp.get(0).ok_or(())?;
67		let len = *inp.get(1).ok_or(())?;
68		*inp = &inp[2..];
69		if inp.len() < block as usize * 32 + len as usize { return Err(()); }
70		res[block as usize * 32..block as usize * 32 + len as usize]
71			.copy_from_slice(&inp[..len as usize]);
72		*inp = &inp[len as usize..];
73	}
74	Ok(res)
75}
76
77fn do_read_wire_packet_labels(inp: &mut &[u8], wire_packet: &[u8], name: &mut String, recursion_limit: usize) -> Result<(), ()> {
78	loop {
79		let len = read_u8(inp)? as usize;
80		if len == 0 {
81			if name.is_empty() { *name += "."; }
82			break;
83		} else if len >= 0xc0 && recursion_limit > 0 {
84			let offs = ((len & !0xc0) << 8) | read_u8(inp)? as usize;
85			if offs >= wire_packet.len() { return Err(()); }
86			do_read_wire_packet_labels(&mut &wire_packet[offs..], wire_packet, name, recursion_limit - 1)?;
87			break;
88		}
89		if inp.len() <= len { return Err(()); }
90		*name += core::str::from_utf8(&inp[..len]).map_err(|_| ())?;
91		*name += ".";
92		*inp = &inp[len..];
93		if name.len() > 255 { return Err(()); }
94	}
95	Ok(())
96}
97
98fn read_wire_packet_labels(inp: &mut &[u8], wire_packet: &[u8], name: &mut String) -> Result<(), ()> {
99	do_read_wire_packet_labels(inp, wire_packet, name, 255)
100}
101
102pub(crate) fn read_wire_packet_name(inp: &mut &[u8], wire_packet: &[u8]) -> Result<Name, ()> {
103	let mut name = String::with_capacity(1024);
104	read_wire_packet_labels(inp, wire_packet, &mut name)?;
105	name.try_into()
106}
107
108pub(crate) trait Writer { fn write(&mut self, buf: &[u8]); }
109impl Writer for Vec<u8> { fn write(&mut self, buf: &[u8]) { self.extend_from_slice(buf); } }
110impl Writer for QueryBuf { fn write(&mut self, buf: &[u8]) { self.extend_from_slice(buf); } }
111#[cfg(feature = "validation")]
112impl Writer for crate::crypto::hash::Hasher { fn write(&mut self, buf: &[u8]) { self.update(buf); } }
113pub(crate) fn write_name<W: Writer>(out: &mut W, name: &str) {
114	let canonical_name = name.to_ascii_lowercase();
115	if canonical_name == "." {
116		out.write(&[0]);
117	} else {
118		for label in canonical_name.split('.') {
119			out.write(&(label.len() as u8).to_be_bytes());
120			out.write(label.as_bytes());
121		}
122	}
123}
124pub(crate) fn name_len(name: &Name) -> u16 {
125	if name.as_str() == "." {
126		1
127	} else {
128		let mut res = 0;
129		for label in name.split('.') {
130			res += 1 + label.len();
131		}
132		res as u16
133	}
134}
135
136pub(crate) fn parse_wire_packet_rr(inp: &mut &[u8], wire_packet: &[u8]) -> Result<(RR, u32), ()> {
137	let name = read_wire_packet_name(inp, wire_packet)?;
138	let ty = read_u16(inp)?;
139	let class = read_u16(inp)?;
140	if class != 1 { return Err(()); } // We only support the INternet
141	let ttl = read_u32(inp)?;
142	let data_len = read_u16(inp)? as usize;
143	if inp.len() < data_len { return Err(()); }
144	let data = &inp[..data_len];
145	*inp = &inp[data_len..];
146
147	let rr = match ty {
148		A::TYPE => RR::A(A::read_from_data(name, data, wire_packet)?),
149		AAAA::TYPE => RR::AAAA(AAAA::read_from_data(name, data, wire_packet)?),
150		NS::TYPE => RR::NS(NS::read_from_data(name, data, wire_packet)?),
151		Txt::TYPE => RR::Txt(Txt::read_from_data(name, data, wire_packet)?),
152		CName::TYPE => RR::CName(CName::read_from_data(name, data, wire_packet)?),
153		DName::TYPE => RR::DName(DName::read_from_data(name, data, wire_packet)?),
154		TLSA::TYPE => RR::TLSA(TLSA::read_from_data(name, data, wire_packet)?),
155		DnsKey::TYPE => RR::DnsKey(DnsKey::read_from_data(name, data, wire_packet)?),
156		DS::TYPE => RR::DS(DS::read_from_data(name, data, wire_packet)?),
157		RRSig::TYPE => RR::RRSig(RRSig::read_from_data(name, data, wire_packet)?),
158		NSec::TYPE => RR::NSec(NSec::read_from_data(name, data, wire_packet)?),
159		NSec3::TYPE => RR::NSec3(NSec3::read_from_data(name, data, wire_packet)?),
160		_ => return Err(()),
161	};
162	Ok((rr, ttl))
163}
164
165pub(crate) fn parse_rr(inp: &mut &[u8]) -> Result<RR, ()> {
166	parse_wire_packet_rr(inp, &[]).map(|(rr, _)| rr)
167}
168
169/// Parse a stream of [`RR`]s from the format described in [RFC 9102](https://www.rfc-editor.org/rfc/rfc9102.html).
170///
171/// Note that this is only the series of `AuthenticationChain` records, and does not read the
172/// `ExtSupportLifetime` field at the start of a `DnssecChainExtension`.
173pub fn parse_rr_stream(mut inp: &[u8]) -> Result<Vec<RR>, ()> {
174	let mut res = Vec::with_capacity(32);
175	while !inp.is_empty() {
176		let rr = parse_rr(&mut inp)?;
177		#[cfg(fuzzing)]
178		let _ = rr.json(); // Make sure we can JSON the RR when fuzzing, cause why not
179		res.push(rr);
180	}
181	Ok(res)
182}
183
184/// Writes the given resource record in its wire encoding to the given `Vec`.
185///
186/// An [RFC 9102](https://www.rfc-editor.org/rfc/rfc9102.html) `AuthenticationChain` is simply a
187/// series of such records with no additional bytes in between.
188pub fn write_rr<RR: Record>(rr: &RR, ttl: u32, out: &mut Vec<u8>) {
189	write_name(out, rr.name());
190	out.extend_from_slice(&rr.ty().to_be_bytes());
191	out.extend_from_slice(&1u16.to_be_bytes()); // The INternet class
192	out.extend_from_slice(&ttl.to_be_bytes());
193	rr.write_u16_len_prefixed_data(out);
194}
dnssec_prover/ser.rs

dnssec_prover/
ser.rs
