eth_block fetching RPCs

ethcore/light/src/client/header_chain.rs

@@ -411,6 +411,28 @@ impl HeaderChain {
 		}
 	}
 
+	/// Get a block's chain score.
+	/// Returns nothing for non-canonical blocks.
+	pub fn score(&self, id: BlockId) -> Option<U256> {
+		let genesis_hash = self.genesis_hash();
+		match id {
+			BlockId::Earliest | BlockId::Number(0) => Some(self.genesis_header.difficulty()),
+			BlockId::Hash(hash) if hash == genesis_hash => Some(self.genesis_header.difficulty()),
+			BlockId::Hash(hash) => match self.block_header(BlockId::Hash(hash)) {
+				Some(header) => self.candidates.read().get(&header.number())
+					.and_then(|era| era.candidates.iter().find(|e| e.hash == hash))
+					.map(|c| c.total_difficulty),
+				None => None,
+			},
+			BlockId::Number(num) => {
+				let candidates = self.candidates.read();
+				if self.best_block.read().number < num { return None }
+				candidates.get(&num).map(|era| era.candidates[0].total_difficulty)
+			}
+			BlockId::Latest | BlockId::Pending => Some(self.best_block.read().total_difficulty)
+		}
+	}
+
 	/// Get the best block's header.
 	pub fn best_header(&self) -> encoded::Header {
 		self.block_header(BlockId::Latest).expect("Header for best block always stored; qed")

ethcore/light/src/client/mod.rs

@@ -31,7 +31,7 @@ use ethcore::service::ClientIoMessage;
 use ethcore::encoded;
 use io::IoChannel;
 
-use util::{H256, Mutex, RwLock};
+use util::{H256, U256, Mutex, RwLock};
 use util::kvdb::{KeyValueDB, CompactionProfile};
 
 use self::header_chain::{AncestryIter, HeaderChain};
@@ -74,6 +74,9 @@ pub trait LightChainClient: Send + Sync {
 	/// Get the best block header.
 	fn best_block_header(&self) -> encoded::Header;
 
+	/// Get a block's chain score by ID.
+	fn score(&self, id: BlockId) -> Option<U256>;
+
 	/// Get an iterator over a block and its ancestry.
 	fn ancestry_iter<'a>(&'a self, start: BlockId) -> Box<Iterator<Item=encoded::Header> + 'a>;
 
@@ -199,6 +202,11 @@ impl Client {
 		self.chain.best_header()
 	}
 
+	/// Get a block's chain score.
+	pub fn score(&self, id: BlockId) -> Option<U256> {
+		self.chain.score(id)
+	}
+
 	/// Get an iterator over a block and its ancestry.
 	pub fn ancestry_iter(&self, start: BlockId) -> AncestryIter {
 		self.chain.ancestry_iter(start)
@@ -328,6 +336,10 @@ impl LightChainClient for Client {
 		Client::best_block_header(self)
 	}
 
+	fn score(&self, id: BlockId) -> Option<U256> {
+		Client::score(self, id)
+	}
+
 	fn ancestry_iter<'a>(&'a self, start: BlockId) -> Box<Iterator<Item=encoded::Header> + 'a> {
 		Box::new(Client::ancestry_iter(self, start))
 	}

ethcore/src/types/encoded.rs

@@ -199,6 +199,12 @@ impl Block {
 	/// Decode to a full block.
 	pub fn decode(&self) -> FullBlock { ::rlp::decode(&self.0) }
 
+	/// Decode the header.
+	pub fn decode_header(&self) -> FullHeader { self.rlp().val_at(0) }
+
+	/// Clone the encoded header.
+	pub fn header(&self) -> Header { Header(self.rlp().at(0).as_raw().to_vec()) }
+
 	/// Get the rlp of this block.
 	#[inline]
 	pub fn rlp(&self) -> Rlp {