Backports to beta (#7660)

* Improve handling of RocksDB corruption (#7630)

* kvdb-rocksdb: update rust-rocksdb version

* kvdb-rocksdb: mark corruptions and attempt repair on db open

* kvdb-rocksdb: better corruption detection on open

* kvdb-rocksdb: add corruption_file_name const

* kvdb-rocksdb: rename mark_corruption to check_for_corruption

* Hardening of CSP (#7621)

* Fixed delegatecall's from/to (#7568)

* Fixed delegatecall's from/to, closes #7166

* added tests for delegatecall traces, #7167

* Light client RPCs (#7603)

* Implement registrar.

* Implement eth_getCode

* Don't wait for providers.

* Don't wait for providers.

* Fix linting and wasm tests.

* Problem: AttachedProtocols don't get registered (#7610)

I was investigating issues I am having with Whisper support. I've
enabled Whisper on a custom test network and inserted traces into
Whisper handler implementation (Network<T> and NetworkProtocolHandler
for Network<T>) and I noticed that the handler was never invoked.

After further research on this matter, I found out that
AttachedProtocol's register function does nothing:
https://github.com/paritytech/parity/blob/master/sync/src/api.rs#L172
but there was an implementation originally:
99075ad#diff-5212acb6bcea60e9804ba7b50f6fe6ec and it did the actual
expected logic of registering the protocol in the NetworkService.

However, as of 16d84f8#diff-5212acb6bcea60e9804ba7b50f6fe6ec ("finished
removing ipc") this implementation is gone and only the no-op function
is left.

Which leads me to a conclusion that in fact Whisper's handler never gets
registered in the service and therefore two nodes won't communicate
using it.

Solution: Resurrect original non-empty `AttachedProtocols.register`
implementation

Resolves #7566

* Fix Temporarily Invalid blocks handling (#7613)

* Handle temporarily invalid blocks in sync.

* Fix tests.

rpc/src/v1/helpers/light_fetch.rs

@@ -147,19 +147,30 @@ impl LightFetch {
 			Err(e) => return Box::new(future::err(e)),
 		};
 
-		let maybe_future = self.sync.with_context(move |ctx| {
-			Box::new(self.on_demand.request_raw(ctx, reqs)
-				.expect("all back-references known to be valid; qed")
-				.map(|res| extract_header(&res, header_ref)
-					.expect("these responses correspond to requests that header_ref belongs to. \
-							 therefore it will not fail; qed"))
-				.map_err(errors::on_demand_cancel))
-		});
 
-		match maybe_future {
-			Some(recv) => recv,
-			None => Box::new(future::err(errors::network_disabled()))
-		}
+		self.send_requests(reqs, |res|
+			extract_header(&res, header_ref)
+				.expect("these responses correspond to requests that header_ref belongs to \
+						therefore it will not fail; qed")
+		)
+	}
+
+	/// Helper for getting contract code at a given block.
+	pub fn code(&self, address: Address, id: BlockId) -> BoxFuture<Vec<u8>> {
+		let mut reqs = Vec::new();
+		let header_ref = match self.make_header_requests(id, &mut reqs) {
+			Ok(r) => r,
+			Err(e) => return Box::new(future::err(e)),
+		};
+
+		reqs.push(request::Account { header: header_ref.clone(), address: address }.into());
+		let account_idx = reqs.len() - 1;
+		reqs.push(request::Code { header: header_ref, code_hash: Field::back_ref(account_idx, 0) }.into());
+
+		self.send_requests(reqs, |mut res| match res.pop() {
+			Some(OnDemandResponse::Code(code)) => code,
+			_ => panic!("responses correspond directly with requests in amount and type; qed"),
+		})
 	}
 
 	/// Helper for getting account info at a given block.
@@ -173,20 +184,10 @@ impl LightFetch {
 
 		reqs.push(request::Account { header: header_ref, address: address }.into());
 
-		let maybe_future = self.sync.with_context(move |ctx| {
-			Box::new(self.on_demand.request_raw(ctx, reqs)
-				.expect("all back-references known to be valid; qed")
-				.map(|mut res| match res.pop() {
-					Some(OnDemandResponse::Account(acc)) => acc,
-					_ => panic!("responses correspond directly with requests in amount and type; qed"),
-				})
-				.map_err(errors::on_demand_cancel))
-		});
-
-		match maybe_future {
-			Some(recv) => recv,
-			None => Box::new(future::err(errors::network_disabled()))
-		}
+		self.send_requests(reqs, |mut res|match res.pop() {
+			Some(OnDemandResponse::Account(acc)) => acc,
+			_ => panic!("responses correspond directly with requests in amount and type; qed"),
+		})
 	}
 
 	/// Helper for getting proved execution.
@@ -277,20 +278,10 @@ impl LightFetch {
 
 		reqs.push(request::Body(header_ref).into());
 
-		let maybe_future = self.sync.with_context(move |ctx| {
-			Box::new(self.on_demand.request_raw(ctx, reqs)
-				.expect(NO_INVALID_BACK_REFS)
-				.map(|mut res| match res.pop() {
-					Some(OnDemandResponse::Body(b)) => b,
-					_ => panic!("responses correspond directly with requests in amount and type; qed"),
-				})
-				.map_err(errors::on_demand_cancel))
-		});
-
-		match maybe_future {
-			Some(recv) => recv,
-			None => Box::new(future::err(errors::network_disabled()))
-		}
+		self.send_requests(reqs, |mut res| match res.pop() {
+			Some(OnDemandResponse::Body(b)) => b,
+			_ => panic!("responses correspond directly with requests in amount and type; qed"),
+		})
 	}
 
 	/// Get the block receipts. Fails on unknown block ID.
@@ -303,20 +294,10 @@ impl LightFetch {
 
 		reqs.push(request::BlockReceipts(header_ref).into());
 
-		let maybe_future = self.sync.with_context(move |ctx| {
-			Box::new(self.on_demand.request_raw(ctx, reqs)
-				.expect(NO_INVALID_BACK_REFS)
-				.map(|mut res| match res.pop() {
-					Some(OnDemandResponse::Receipts(b)) => b,
-					_ => panic!("responses correspond directly with requests in amount and type; qed"),
-				})
-				.map_err(errors::on_demand_cancel))
-		});
-
-		match maybe_future {
-			Some(recv) => recv,
-			None => Box::new(future::err(errors::network_disabled()))
-		}
+		self.send_requests(reqs, |mut res| match res.pop() {
+			Some(OnDemandResponse::Receipts(b)) => b,
+			_ => panic!("responses correspond directly with requests in amount and type; qed"),
+		})
 	}
 
 	/// Get transaction logs
@@ -433,6 +414,23 @@ impl LightFetch {
 			Either::B(extract_transaction)
 		}))
 	}
+
+	fn send_requests<T, F>(&self, reqs: Vec<OnDemandRequest>, parse_response: F) -> BoxFuture<T> where
+		F: FnOnce(Vec<OnDemandResponse>) -> T + Send + 'static,
+		T: Send + 'static,
+	{
+		let maybe_future = self.sync.with_context(move |ctx| {
+			Box::new(self.on_demand.request_raw(ctx, reqs)
+					 .expect(NO_INVALID_BACK_REFS)
+					 .map(parse_response)
+					 .map_err(errors::on_demand_cancel))
+		});
+
+		match maybe_future {
+			Some(recv) => recv,
+			None => Box::new(future::err(errors::network_disabled()))
+		}
+	}
 }
 
 #[derive(Clone)]

rpc/src/v1/impls/light/eth.rs

@@ -349,8 +349,8 @@ impl<T: LightChainClient + 'static> Eth for EthClient<T> {
 		}))
 	}
 
-	fn code_at(&self, _address: RpcH160, _num: Trailing<BlockNumber>) -> BoxFuture<Bytes> {
-		Box::new(future::err(errors::unimplemented(None)))
+	fn code_at(&self, address: RpcH160, num: Trailing<BlockNumber>) -> BoxFuture<Bytes> {
+		Box::new(self.fetcher().code(address.into(), num.unwrap_or_default().into()).map(Into::into))
 	}
 
 	fn send_raw_transaction(&self, raw: Bytes) -> Result<RpcH256> {

rpc/src/v1/impls/light/parity.rs

@@ -208,7 +208,12 @@ impl Parity for ParityClient {
 	}
 
 	fn registry_address(&self) -> Result<Option<H160>> {
-		Err(errors::light_unimplemented(None))
+		let reg = self.light_dispatch.client.engine().params().registrar;
+		if reg == Default::default() {
+			Ok(None)
+		} else {
+			Ok(Some(reg.into()))
+		}
 	}
 
 	fn rpc_settings(&self) -> Result<RpcSettings> {