RPC & Client (#21)

* Initial version of http server.

* Refactor the structure.

* add unassigned ports info.

* Rename servers to match conventions.

* Add client crate and some proper RPC implementations.

* Style & docs.

substrate/rpc/src/chain/error.rs

@@ -0,0 +1,40 @@
+// Copyright 2017 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+use rpc;
+
+error_chain! {
+	errors {
+		/// Not implemented yet
+		Unimplemented {
+			description("not yet implemented"),
+			display("Method Not Implemented"),
+		}
+	}
+}
+
+impl From<Error> for rpc::Error {
+	fn from(e: Error) -> Self {
+		match e {
+			Error(ErrorKind::Unimplemented, _) => rpc::Error {
+				code: rpc::ErrorCode::ServerError(-1),
+				message: "Not implemented yet".into(),
+				data: None,
+			},
+			_ => rpc::Error::internal_error(),
+		}
+	}
+}

substrate/rpc/src/chain/mod.rs

@@ -0,0 +1,45 @@
+// Copyright 2017 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Polkadot blockchain API.
+
+use primitives::block;
+use client;
+
+mod error;
+
+#[cfg(test)]
+mod tests;
+
+use self::error::{Result, ResultExt};
+
+build_rpc_trait! {
+	/// Polkadot blockchain API
+	pub trait ChainApi {
+		/// Get header of a relay chain block.
+		#[rpc(name = "chain_getHeader")]
+		fn header(&self, block::HeaderHash) -> Result<Option<block::Header>>;
+	}
+}
+
+impl<B> ChainApi for B where
+	B: client::Blockchain + Send + Sync + 'static,
+	B::Error: ::std::error::Error + Send,
+{
+	fn header(&self, hash: block::HeaderHash) -> Result<Option<block::Header>> {
+		self.header(&hash).chain_err(|| "Blockchain error")
+	}
+}

substrate/rpc/src/chain/tests.rs

@@ -0,0 +1,39 @@
+// Copyright 2017 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+use super::*;
+
+use test_helpers::Blockchain;
+
+#[test]
+fn should_return_header() {
+	let state = Blockchain::default();
+
+	assert_matches!(
+		ChainApi::header(&state, 0.into()),
+		Ok(Some(ref x)) if x == &block::Header {
+			parent_hash: 0.into(),
+			state_root: 0.into(),
+			timestamp: 0,
+			number: 0,
+		}
+	);
+
+	assert_matches!(
+		ChainApi::header(&state, 5.into()),
+		Ok(None)
+	);
+}