Replace RLP header view usage with safe decoding

Using the view will panic with invalid RLP. Here we use Rlp decoding directly which will return a `Result<_, DecoderError>`. While this path currently should not have any invalid RLP - it makes it safer if ever called with invalid RLP from other code paths.

ethcore/src/client/client.rs

@@ -447,9 +447,7 @@ impl Importer {
 	///
 	/// The block is guaranteed to be the next best blocks in the
 	/// first block sequence. Does no sealing or transaction validation.
-	fn import_old_block(&self, block_bytes: Bytes, receipts_bytes: Bytes, db: &KeyValueDB, chain: &BlockChain) -> Result<H256, ::error::Error> {
-		let block = view!(BlockView, &block_bytes);
-		let header = block.header();
+	fn import_old_block(&self, header: &Header, block_bytes: Bytes, receipts_bytes: Bytes, db: &KeyValueDB, chain: &BlockChain) -> Result<H256, ::error::Error> {
 		let receipts = ::rlp::decode_list(&receipts_bytes);
 		let hash = header.hash();
 		let _import_lock = self.import_lock.lock();
@@ -1423,19 +1421,19 @@ impl ImportBlock for Client {
 	}
 
 	fn import_block_with_receipts(&self, block_bytes: Bytes, receipts_bytes: Bytes) -> Result<H256, BlockImportError> {
+		let header: Header = ::rlp::Rlp::new(&block_bytes).val_at(0)?; 
 		{
 			// check block order
-			let header = view!(BlockView, &block_bytes).header_view();
 			if self.chain.read().is_known(&header.hash()) {
 				bail!(BlockImportErrorKind::Import(ImportErrorKind::AlreadyInChain));
 			}
-			let status = self.block_status(BlockId::Hash(header.parent_hash()));
+			let status = self.block_status(BlockId::Hash(*header.parent_hash()));
 			if status == BlockStatus::Unknown || status == BlockStatus::Pending {
-				bail!(BlockImportErrorKind::Block(BlockError::UnknownParent(header.parent_hash())));
+				bail!(BlockImportErrorKind::Block(BlockError::UnknownParent(*header.parent_hash())));
 			}
 		}
 
-		self.importer.import_old_block(block_bytes, receipts_bytes, &**self.db.read(), &*self.chain.read()).map_err(Into::into)
+		self.importer.import_old_block(&header, block_bytes, receipts_bytes, &**self.db.read(), &*self.chain.read()).map_err(Into::into)
 	}
 }