Bad blocks RPC + reporting (#9433)

* Bad blocks RPC.

* Return bad blocks via RPC.

* Fix test.

* More verbose bad block message.

* Expose via CLI.

* Remove stray whitespace.

* Remove stray newline.

* Fix tests.

ethcore/src/client/bad_blocks.rs

@@ -0,0 +1,81 @@
+// Copyright 2015-2018 Parity Technologies (UK) Ltd.
+// This file is part of Parity.
+
+// Parity 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.
+
+// Parity 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 Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Stores recently seen bad blocks.
+
+use bytes::{Bytes, ToPretty};
+use ethereum_types::H256;
+use itertools::Itertools;
+use memory_cache::MemoryLruCache;
+use parking_lot::RwLock;
+use verification::queue::kind::blocks::Unverified;
+
+/// Recently seen bad blocks.
+pub struct BadBlocks {
+	last_blocks: RwLock<MemoryLruCache<H256, (Unverified, String)>>,
+}
+
+impl Default for BadBlocks {
+	fn default() -> Self {
+		BadBlocks {
+			last_blocks: RwLock::new(MemoryLruCache::new(8 * 1024 * 1024)),
+		}
+	}
+}
+
+impl BadBlocks {
+	/// Reports given RLP as invalid block.
+	pub fn report(&self, raw: Bytes, message: String) {
+		match Unverified::from_rlp(raw) {
+			Ok(unverified) => {
+				error!(
+					target: "client",
+					"\nBad block detected: {}\nRLP: {}\nHeader: {:?}\nUncles: {}\nTransactions:{}\n",
+					message,
+					unverified.bytes.to_hex(),
+					unverified.header,
+					unverified.uncles
+						.iter()
+						.enumerate()
+						.map(|(index, uncle)| format!("[Uncle {}] {:?}", index, uncle))
+						.join("\n"),
+					unverified.transactions
+						.iter()
+						.enumerate()
+						.map(|(index, tx)| format!("[Tx {}] {:?}", index, tx))
+						.join("\n"),
+				);
+				self.last_blocks.write().insert(unverified.header.hash(), (unverified, message));
+			},
+			Err(err) => {
+				error!(target: "client", "Bad undecodable block detected: {}\n{:?}", message, err);
+			},
+		}
+	}
+
+	/// Returns a list of recently detected bad blocks with error descriptions.
+	pub fn bad_blocks(&self) -> Vec<(Unverified, String)> {
+		self.last_blocks.read()
+			.backstore()
+			.iter()
+			.map(|(_k, (unverified, message))| (
+				Unverified::from_rlp(unverified.bytes.clone())
+					.expect("Bytes coming from UnverifiedBlock so decodable; qed"),
+				message.clone(),
+			))
+			.collect()
+	}
+}