From 90c66a8079b553cfd5cbff58e5263eee431087ea Mon Sep 17 00:00:00 2001
From: debris <marek.kotewicz@gmail.com>
Date: Sat, 28 Nov 2015 11:25:00 +0100
Subject: [PATCH] rlp encoding and decoding of fixed sized hashes

---
 src/bytes.rs | 39 ++++++++++++++++++++++++++++++++++++++-
 src/hash.rs  |  5 +++++
 src/rlp.rs   | 26 ++++++++++++++++++++++++++
 3 files changed, 69 insertions(+), 1 deletion(-)

diff --git a/src/bytes.rs b/src/bytes.rs
index 0f82748a1..c08c4ee2a 100644
--- a/src/bytes.rs
+++ b/src/bytes.rs
@@ -35,8 +35,10 @@
 //! ```
 
 use std::fmt;
+use std::cmp::Ordering;
 use std::error::Error as StdError;
 use uint::{U128, U256};
+use hash::FixedHash;
 
 /// Vector of bytes
 pub type Bytes = Vec<u8>;
@@ -173,10 +175,26 @@ macro_rules! impl_uint_to_bytes {
 impl_uint_to_bytes!(U256);
 impl_uint_to_bytes!(U128);
 
+impl <T>ToBytes for T where T: FixedHash {
+	fn to_bytes(&self) -> Vec<u8> {
+		let mut res: Vec<u8> = vec![];
+		res.reserve(T::size());
+
+		unsafe {
+			use std::ptr;
+			ptr::copy(self.bytes().as_ptr(), res.as_mut_ptr(), T::size());
+			res.set_len(T::size());
+		}
+		
+		res
+	}
+}
+
 /// Error returned when FromBytes conversation goes wrong
 #[derive(Debug, PartialEq, Eq)]
 pub enum FromBytesError {
-	UnexpectedEnd
+	DataIsTooShort,
+	DataIsTooLong
 }
 
 impl StdError for FromBytesError {
@@ -256,3 +274,22 @@ macro_rules! impl_uint_from_bytes {
 
 impl_uint_from_bytes!(U256);
 impl_uint_from_bytes!(U128);
+
+impl <T>FromBytes for T where T: FixedHash {
+	fn from_bytes(bytes: &[u8]) -> FromBytesResult<T> {
+		match bytes.len().cmp(&T::size()) {
+			Ordering::Less => return Err(FromBytesError::DataIsTooShort),
+			Ordering::Greater => return Err(FromBytesError::DataIsTooLong),
+			Ordering::Equal => ()
+		};
+
+		unsafe {
+			use std::{mem, ptr};
+
+			let mut res: T = mem::uninitialized();
+			ptr::copy(bytes.as_ptr(), res.mut_bytes().as_mut_ptr(), T::size());
+
+			Ok(res)
+		}
+	}
+}
diff --git a/src/hash.rs b/src/hash.rs
index 0dfd4f487..a0493f2bb 100644
--- a/src/hash.rs
+++ b/src/hash.rs
@@ -14,6 +14,7 @@ pub trait FixedHash: Sized + BytesConvertable {
 	fn new() -> Self;
 	fn random() -> Self;
 	fn randomize(&mut self);
+	fn size() -> usize;
 	fn mut_bytes(&mut self) -> &mut [u8];
 	fn shift_bloom<'a, T>(&'a mut self, b: &T) -> &'a mut Self where T: FixedHash;
 	fn bloom_part<T>(&self, m: usize) -> T where T: FixedHash;
@@ -47,6 +48,10 @@ macro_rules! impl_hash {
 				rng.fill_bytes(&mut self.0);
 			}
 
+			fn size() -> usize {
+				$size
+			}
+
 			fn mut_bytes(&mut self) -> &mut [u8] {
 				&mut self.0
 			}
diff --git a/src/rlp.rs b/src/rlp.rs
index 8fbe8cf8f..4b6df2c6e 100644
--- a/src/rlp.rs
+++ b/src/rlp.rs
@@ -748,6 +748,19 @@ mod tests {
 		run_encode_tests(tests);
 	}
 
+	#[test]
+	fn encode_address() {
+		use hash::*;
+
+		let tests = vec![
+			ETestPair(Address::from_str("ef2d6d194084c2de36e0dabfce45d046b37d1106").unwrap(), 
+					  vec![0x94, 0xef, 0x2d, 0x6d, 0x19, 0x40, 0x84, 0xc2, 0xde,
+					  	   		 0x36, 0xe0, 0xda, 0xbf, 0xce, 0x45, 0xd0, 0x46,
+						   		 0xb3, 0x7d, 0x11, 0x06])
+		];
+		run_encode_tests(tests);
+	}
+
 	#[test]
 	fn encode_vector_u8() {
 		let tests = vec![
@@ -891,6 +904,19 @@ mod tests {
 		run_decode_tests(tests);
 	}
 
+	#[test]
+	fn decode_address() {
+		use hash::*;
+
+		let tests = vec![
+			DTestPair(Address::from_str("ef2d6d194084c2de36e0dabfce45d046b37d1106").unwrap(), 
+					  vec![0x94, 0xef, 0x2d, 0x6d, 0x19, 0x40, 0x84, 0xc2, 0xde,
+					  	   		 0x36, 0xe0, 0xda, 0xbf, 0xce, 0x45, 0xd0, 0x46,
+						   		 0xb3, 0x7d, 0x11, 0x06])
+		];
+		run_decode_tests(tests);
+	}
+
 	#[test]
 	fn decode_vector_u8() {
 		let tests = vec![