Added support for contract code by hash.

This is done by requests sending CID with raw binary codec (0x55).
Note: this functionality is exactly the same as fetching state-trie
due to how db internals work in Parity atm.

ipfs/src/error.rs

@@ -36,6 +36,7 @@ pub enum Error {
 	BlockNotFound,
 	TransactionNotFound,
 	StateRootNotFound,
+	ContractNotFound,
 }
 
 /// Convert Error into Out, handy when switching from Rust's Result-based
@@ -51,6 +52,7 @@ impl From<Error> for Out {
 			BlockNotFound => Out::NotFound("Block not found"),
 			TransactionNotFound => Out::NotFound("Transaction not found"),
 			StateRootNotFound => Out::NotFound("State root not found"),
+			ContractNotFound => Out::NotFound("Contract not found"),
 		}
 	}
 }

ipfs/src/handler.rs

@@ -86,6 +86,7 @@ impl IpfsHandler {
 			Codec::EthereumBlockList => self.block_list(hash),
 			Codec::EthereumTx => self.transaction(hash),
 			Codec::EthereumStateTrie => self.state_trie(hash),
+			Codec::Raw => self.contract_code(hash),
 			_ => return Err(Error::UnsupportedCid),
 		}
 	}
@@ -119,6 +120,13 @@ impl IpfsHandler {
 
 		Ok(Out::OctetStream(data))
 	}
+
+	/// Get state trie node by hash and return as raw binary.
+	fn contract_code(&self, hash: H256) -> Result<Out> {
+		let data = self.client.state_data(&hash).ok_or(Error::ContractNotFound)?;
+
+		Ok(Out::OctetStream(data))
+	}
 }
 
 /// Get a query parameter's value by name.
@@ -192,6 +200,16 @@ mod tests {
 		assert_eq!(Err(Error::StateRootNotFound), handler.route_cid(&cid));
 	}
 
+	#[test]
+	fn cid_route_contract_code() {
+		let handler = get_mocked_handler();
+
+		// `raw` with Keccak-256
+		let cid = "zb34WAp1Q5fhtLGZ3w3jhnTWaNbVV5ZZvGq4vuJQzERj6Pu3H";
+
+		assert_eq!(Err(Error::ContractNotFound), handler.route_cid(&cid));
+	}
+
 	#[test]
 	fn cid_route_invalid_hash() {
 		let handler = get_mocked_handler();