rust-dnsbox/lib/dnsbox-base/src/records/unknown.rs

use crate::common_types::binary::HEXLOWER_PERMISSIVE_ALLOW_WS;
use crate::common_types::*;
use crate::errors::*;
use crate::ser::packet::{remaining_bytes, DnsPacketWriteContext};
use crate::ser::text::{next_field, DnsTextContext, DnsTextFormatter};
use crate::ser::{RRData, RRDataPacket, RRDataText};
use bytes::{BufMut, Bytes};
use failure::{Fail, ResultExt};
use std::borrow::Cow;
use std::fmt;
use std::io::Cursor;

#[derive(Clone, PartialEq, Eq, Debug)]
pub struct UnknownRecord {
	rr_type: Type,
	raw: Bytes,
}

impl UnknownRecord {
	pub fn new(rr_type: Type, raw: Bytes) -> Self {
		UnknownRecord {
			rr_type: rr_type,
			raw: raw,
		}
	}

	pub fn raw(&self) -> &Bytes {
		&self.raw
	}

	pub fn deserialize(rr_type: Type, data: &mut ::std::io::Cursor<Bytes>) -> Result<Self> {
		Ok(UnknownRecord::new(rr_type, remaining_bytes(data)))
	}

	pub fn dns_parse(rr_type: Type, data: &mut &str) -> Result<Self> {
		let field = next_field(data)?;
		failure::ensure!(field == r"\#", "expect \\# token to mark generic encoding");
		let field = next_field(data).context("generic record data length")?;
		let len: usize = field.parse()?;

		let result = HEXLOWER_PERMISSIVE_ALLOW_WS
			.decode(data.as_bytes())
			.with_context(|e| e.context(format!("invalid hex: {:?}", data)))?;
		failure::ensure!(
			len == result.len(),
			"length {} doesn't match length of encoded data {}",
			len,
			result.len()
		);
		*data = ""; // read all data

		Ok(UnknownRecord {
			rr_type,
			raw: result.into(),
		})
	}
}

impl RRDataPacket for UnknownRecord {
	fn deserialize_rr_data(
		_ttl: u32,
		_rr_class: Class,
		rr_type: Type,
		data: &mut Cursor<Bytes>,
	) -> Result<Self> {
		UnknownRecord::deserialize(rr_type, data)
	}

	fn rr_type(&self) -> Type {
		self.rr_type
	}

	fn serialize_rr_data(
		&self,
		_context: &mut DnsPacketWriteContext,
		packet: &mut Vec<u8>,
	) -> Result<()> {
		packet.reserve(self.raw.len());
		packet.put_slice(&self.raw);
		Ok(())
	}
}

impl RRDataText for UnknownRecord {
	fn dns_parse_rr_data(context: &DnsTextContext, data: &mut &str) -> Result<Self>
	where
		Self: Sized,
	{
		let t = match context.record_type() {
			Some(t) => t,
			None => failure::bail!("must parse DNS record with record type context"),
		};

		UnknownRecord::dns_parse(t, data)
	}

	/// this must never fail unless the underlying buffer fails.
	fn dns_format_rr_data(&self, f: &mut DnsTextFormatter) -> fmt::Result {
		write!(
			f,
			"\\# {} {}",
			self.raw.len(),
			HEXLOWER_PERMISSIVE_ALLOW_WS.encode(&self.raw)
		)
	}

	fn rr_type_txt(&self) -> Cow<'static, str> {
		Cow::Owned(self.rr_type.generic_name())
	}
}

impl RRData for UnknownRecord {
	fn clone_box(&self) -> Box<dyn RRData> {
		Box::new(self.clone()) as _
	}

	fn as_any(&self) -> &dyn ::std::any::Any {
		self as _
	}
}