Simple macro to remove some of the verbosity in deserialization.

core/src/core/block.rs

@@ -123,23 +123,18 @@ impl Writeable for Block {
 /// from a binary stream.
 impl Readable<Block> for Block {
 	fn read(reader: &mut Reader) -> Result<Block, ser::Error> {
-		let height = try!(reader.read_u64());
-		let previous = try!(reader.read_fixed_bytes(32));
-		let timestamp = try!(reader.read_i64());
-		let utxo_merkle = try!(reader.read_fixed_bytes(32));
-		let tx_merkle = try!(reader.read_fixed_bytes(32));
-		let total_fees = try!(reader.read_u64());
-		let nonce = try!(reader.read_u64());
+    let (height, previous, timestamp, utxo_merkle, tx_merkle, total_fees, nonce) =
+      ser_multiread!(reader, read_u64, read_32_bytes, read_i64, read_32_bytes, read_32_bytes, read_u64, read_u64);
+
 		// cuckoo cycle of 42 nodes
 		let mut pow = [0; PROOFSIZE];
 		for n in 0..PROOFSIZE {
 			pow[n] = try!(reader.read_u32());
 		}
-		let td = try!(reader.read_u64());
 
-		let input_len = try!(reader.read_u64());
-		let output_len = try!(reader.read_u64());
-		let proof_len = try!(reader.read_u64());
+    let (td, input_len, output_len, proof_len) =
+      ser_multiread!(reader, read_u64, read_u64, read_u64, read_u64);
+
 		if input_len > MAX_IN_OUT_LEN || output_len > MAX_IN_OUT_LEN || proof_len > MAX_IN_OUT_LEN {
 			return Err(ser::Error::TooLargeReadErr("Too many inputs, outputs or proofs.".to_string()));
 		}
@@ -147,6 +142,7 @@ impl Readable<Block> for Block {
 		let inputs = try!((0..input_len).map(|_| Input::read(reader)).collect());
 		let outputs = try!((0..output_len).map(|_| Output::read(reader)).collect());
 		let proofs = try!((0..proof_len).map(|_| TxProof::read(reader)).collect());
+
 		Ok(Block {
 			header: BlockHeader {
 				height: height,

core/src/core/transaction.rs

@@ -47,8 +47,7 @@ impl Writeable for TxProof {
 
 impl Readable<TxProof> for TxProof {
 	fn read(reader: &mut Reader) -> Result<TxProof, ser::Error> {
-		let remainder = try!(reader.read_fixed_bytes(33));
-		let sig = try!(reader.read_vec());
+    let (remainder, sig) = ser_multiread!(reader, read_33_bytes, read_vec);
 		Ok(TxProof {
 			remainder: Commitment::from_vec(remainder),
 			sig: sig,
@@ -88,10 +87,8 @@ impl Writeable for Transaction {
 /// transaction from a binary stream.
 impl Readable<Transaction> for Transaction {
 	fn read(reader: &mut Reader) -> Result<Transaction, ser::Error> {
-		let fee = try!(reader.read_u64());
-		let zerosig = try!(reader.read_vec());
-		let input_len = try!(reader.read_u64());
-		let output_len = try!(reader.read_u64());
+    let (fee, zerosig, input_len, output_len) =
+      ser_multiread!(reader, read_u64, read_vec, read_u64, read_u64);
 
 		// in case a facetious miner sends us more than what we can allocate
 		if input_len > MAX_IN_OUT_LEN || output_len > MAX_IN_OUT_LEN {
@@ -314,8 +311,7 @@ impl Writeable for Output {
 /// an Output from a binary stream.
 impl Readable<Output> for Output {
 	fn read(reader: &mut Reader) -> Result<Output, ser::Error> {
-		let commit = try!(reader.read_fixed_bytes(33));
-		let proof = try!(reader.read_vec());
+    let (commit, proof) = ser_multiread!(reader, read_33_bytes, read_vec);
 		Ok(Output::BlindOutput {
 			commit: Commitment::from_vec(commit),
 			proof: RangeProof::from_vec(proof),

core/src/macros.rs

@@ -71,3 +71,17 @@ macro_rules! try_m {
 		}
   }
 }
+
+/// Eliminate some of the boilerplate of deserialization (package ser) by passing just the list of reader function.
+/// Example before:
+///   let foo = try!(reader.read_u64());
+///   let bar = try!(reader.read_u32());
+/// Example after:
+///   let (foo, bar) = ser_multiread!(reader, read_u64, read_u32);
+#[macro_export]
+macro_rules! ser_multiread {
+  ($rdr:ident, $($read_call:ident),*) => {
+    ( $(try!($rdr.$read_call())),* )
+  }
+}
+

core/src/ser.rs

@@ -28,6 +28,11 @@ use byteorder::{ReadBytesExt, WriteBytesExt, BigEndian};
 pub enum Error {
 	/// Wraps an io error produced when reading or writing
 	IOErr(io::Error),
+  /// Expected a given value that wasn't found
+  UnexpectedData{
+    expected: Vec<u8>,
+    received: Vec<u8>,
+  },
 	/// When asked to read too much data
 	TooLargeReadErr(String),
 }
@@ -42,6 +47,8 @@ pub trait AsFixedBytes {
 /// Implementations defined how different numbers and binary structures are
 /// written to an underlying stream or container (depending on implementation).
 pub trait Writer {
+	/// Writes a u8 as bytes
+  fn write_u8(&mut self, n: u8) -> Option<Error>;
 	/// Writes a u32 as bytes
 	fn write_u32(&mut self, n: u32) -> Option<Error>;
 	/// Writes a u64 as bytes
@@ -59,6 +66,8 @@ pub trait Writer {
 /// Implementations defined how different numbers and binary structures are
 /// read from an underlying stream or container (depending on implementation).
 pub trait Reader {
+	/// Read a u8 from the underlying Read
+	fn read_u8(&mut self) -> Result<u8, Error>;
 	/// Read a u32 from the underlying Read
 	fn read_u32(&mut self) -> Result<u32, Error>;
 	/// Read a u64 from the underlying Read
@@ -69,6 +78,12 @@ pub trait Reader {
 	fn read_vec(&mut self) -> Result<Vec<u8>, Error>;
 	/// Read a fixed number of bytes from the underlying reader.
 	fn read_fixed_bytes(&mut self, length: usize) -> Result<Vec<u8>, Error>;
+  /// Convenience function to read 32 fixed bytes
+  fn read_32_bytes(&mut self) -> Result<Vec<u8>, Error>;
+  /// Convenience function to read 33 fixed bytes
+  fn read_33_bytes(&mut self) -> Result<Vec<u8>, Error>;
+  /// Consumes a byte from the reader, producing an error if it doesn't have the expected value
+  fn expect_u8(&mut self, val: u8) -> Result<u8, Error>;
 }
 
 /// Trait that every type that can be serialized as binary must implement.
@@ -116,6 +131,9 @@ struct BinReader<'a> {
 /// Utility wrapper for an underlying byte Reader. Defines higher level methods
 /// to read numbers, byte vectors, hashes, etc.
 impl<'a> Reader for BinReader<'a> {
+	fn read_u8(&mut self) -> Result<u8, Error> {
+		self.source.read_u8().map_err(Error::IOErr)
+	}
 	fn read_u32(&mut self) -> Result<u32, Error> {
 		self.source.read_u32::<BigEndian>().map_err(Error::IOErr)
 	}
@@ -138,6 +156,16 @@ impl<'a> Reader for BinReader<'a> {
 		let mut buf = vec![0; length];
 		self.source.read_exact(&mut buf).map(move |_| buf).map_err(Error::IOErr)
 	}
+	fn read_32_bytes(&mut self) -> Result<Vec<u8>, Error> {
+    self.read_fixed_bytes(32)
+  }
+	fn read_33_bytes(&mut self) -> Result<Vec<u8>, Error> {
+    self.read_fixed_bytes(33)
+  }
+  fn expect_u8(&mut self, val: u8) -> Result<u8, Error> {
+    let b = try!(self.read_u8());
+    if b == val { Ok(b) } else { Err(Error::UnexpectedData{expected: vec![val], received: vec![b]}) }
+  }
 }
 
 /// Utility wrapper for an underlying byte Writer. Defines higher level methods
@@ -147,6 +175,9 @@ struct BinWriter<'a> {
 }
 
 impl<'a> Writer for BinWriter<'a> {
+	fn write_u8(&mut self, n: u8) -> Option<Error> {
+		self.sink.write_u8(n).err().map(Error::IOErr)
+	}
 	fn write_u32(&mut self, n: u32) -> Option<Error> {
 		self.sink.write_u32::<BigEndian>(n).err().map(Error::IOErr)
 	}