rust-dnsbox/lib/dnsbox-base/src/ser/rrdata.rs

use bytes::Bytes;
use common_types::{Class, Type, classes};
use errors::*;
use ser::DnsPacketData;
use ser::text::{DnsTextData, DnsTextFormatter};
use std::borrow::Cow;
use std::fmt;
use std::io::Cursor;

pub trait RRDataPacket {
	fn deserialize_rr_data(ttl: u32, rr_class: Class, rr_type: Type, data: &mut Cursor<Bytes>) -> Result<Self>
	where
		Self: Sized,
	;

	fn rr_type(&self) -> Type;
}

impl<T: DnsPacketData + StaticRRData> RRDataPacket for T {
	fn deserialize_rr_data(_ttl: u32, rr_class: Class, rr_type: Type, data: &mut Cursor<Bytes>) -> Result<Self> {
		ensure!(rr_type == T::TYPE, "type mismatch");
		if T::CLASS != classes::ANY {
			ensure!(rr_class == T::CLASS, "class mismatch: got {}, need {}", rr_class, T::CLASS);
		}
		T::deserialize(data)
	}

	fn rr_type(&self) -> Type {
		T::TYPE
	}
}

pub trait RRDataText {
	fn dns_parse_rr_data(ttl: u32, rr_class: Class, rr_type: Type, data: &mut &str) -> Result<Self>
	where
		Self: Sized,
	;

	// format might fail if there is no (known) text representation.
	fn dns_format_rr_data(&self, f: &mut DnsTextFormatter) -> fmt::Result;

	fn rr_type_txt(&self) -> Cow<'static, str> {
		unimplemented!()
	}

	// (type, rrdata)
	fn text(&self) -> Result<(String, String)> {
		use std::fmt::Write;
		let mut buf = String::new();
		match write!(&mut buf, "{}", DnsDisplayRR(self)) {
			Ok(()) => {
				return Ok((self.rr_type_txt().into(), buf))
			},
			Err(_) => (),
		}
		buf.clear();
		unimplemented!()
	}
}

impl<T: DnsTextData + StaticRRData> RRDataText for T {
	fn dns_parse_rr_data(_ttl: u32, rr_class: Class, rr_type: Type, data: &mut &str) -> Result<Self>
	where
		Self: Sized,
	{
		ensure!(rr_type == T::TYPE, "type mismatch");
		if T::CLASS != classes::ANY {
			ensure!(rr_class == T::CLASS, "class mismatch: got {}, need {}", rr_class, T::CLASS);
		}
		T::dns_parse(data)
	}

	fn dns_format_rr_data(&self, f: &mut DnsTextFormatter) -> fmt::Result {
		self.dns_format(f)
	}
}

#[derive(Debug)]
pub struct DnsDisplayRR<'a, T: RRDataText + ?Sized + 'a>(pub &'a T);

impl<'a, T: RRDataText + ?Sized + 'a> fmt::Display for DnsDisplayRR<'a, T> {
	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
		self.0.dns_format_rr_data(&mut DnsTextFormatter::new(f))
	}
}

pub trait RRData: RRDataPacket + RRDataText {
}

pub trait StaticRRData: RRData {
	const TYPE: Type;
	const NAME: &'static str;
	// classes::ANY marks class independent types
	const CLASS: Class;
}