Squashed commit of slava-async-bridge:

commit 657deb4cf4b90f24b9c5bfd62764b197776c262c
Author: Hernando Castano <castano.ha@gmail.com>
Date:   Wed Jan 29 20:14:20 2020 -0500

    Move Slava's bridge code into relays folder

commit 4868c42c7da959dde7252766996b3ed4e408e439
Author: Hernando Castano <castano.ha@gmail.com>
Date:   Wed Jan 29 20:01:06 2020 -0500

    Move files into `modules/ethereum`

commit d1093f3e4238acb1a1a020011452cb928d3f8d7a
Merge: 29dc6f9 bfd30ef
Author: Hernando Castano <castano.ha@gmail.com>
Date:   Wed Jan 29 19:59:27 2020 -0500

    Merge branch 'master' of slava-async-bridge

commit 29dc6f97b1b7d1db99086d35a5336f43d2f0f8af
Author: Hernando Castano <castano.ha@gmail.com>
Date:   Wed Jan 29 19:51:31 2020 -0500

    Squashed commit of the following:

    commit 265365920836bb1d286c9b48b1902a2de278fdd9
    Author: Hernando Castano <castano.ha@gmail.com>
    Date:   Wed Jan 29 19:51:15 2020 -0500

        Move hc-jp-bridge repo to different folder

    commit 8271991e95320baba70bd1cb9c4234d0ffd5b638
    Merge: 57d0811 304cbc5
    Author: Hernando Castano <castano.ha@gmail.com>
    Date:   Wed Jan 29 19:36:41 2020 -0500

        Merge branch 'hc-jp-bridge-module' of hc-jp-bridge-module

    commit 304cbc5f02d003ffa5404c1c01e461e5b8539888
    Author: Hernando Castano <HCastano@users.noreply.github.com>
    Date:   Wed Jan 29 00:38:27 2020 -0500

        Update bridge pallet to work with the (almost) lastest master (#4672)

        * Update decl_error usage

        * WIP: Update error handling to use DispatchResult

        * Get module compiling with new error handling

        * Make tests compile again

        Main change was updating the usage of InMemoryBackend

        * Move `sp-state-machine` into dev-dependencies

        * Bump dependencies to v2.0.0

        * Remove some stray comments

        * Appy code review suggestion

    commit 510cd6d96372688517496efa61773ea2839f8474
    Author: Hernando Castano <HCastano@users.noreply.github.com>
    Date:   Tue Dec 17 12:52:51 2019 -0500

        Move Bridge Pallet into FRAME (#4373)

        * Move `bridge` crate into `frame` folder

        * Make `bridge` pallet compile after `the-big-reorg`

    commit ab54e838ef75e6a3f68fd0944bf22598c10c552f
    Author: Hernando Castano <castano.ha@gmail.com>
    Date:   Mon Nov 11 21:56:40 2019 +0100

        Use new StorageProof type from #3834

    commit 8fc8911fd1b4acc2274c6863fb3dba91b30c90af
    Author: Hernando Castano <HCastano@users.noreply.github.com>
    Date:   Tue Nov 5 00:50:34 2019 +0100

        Verify Ancestry between Headers (#3963)

        * Create module for checking ancestry proofs

        * Use Vec of Headers instead of a HashMap

        * Move the ancestry verification into the lib.rs file

        * Change the proof format to exclude `child` and `ancestor` headers

        * Add a testing function for building header chains

        * Rename AncestorNotFound error to InvalidAncestryProof

        * Use ancestor hash instead of header when verifying ancestry

        * Clean up some stuff missed in the merge

    commit dbe85738b68358b790cf927b34a804b965a88f96
    or: Hernando Castano <HCastano@users.noreply.github.com>
    Date:   Fri Nov 1 15:41:58 2019 +0100

        Check given Grandpa validator set against set found in storage (#3915)

        * Make StorageProofChecker happy

        * Update some tests

        * Check given validator set against set found in storage

        * Use Finality Grandpa's Authority Id and Weight

        * Add better error handling

        * Use error type from decl_error! macro

    commit 31b09216603d3e9c21144ce8c0b6bf59307a4f97
    or: Hernando Castano <HCastano@users.noreply.github.com>
    Date:   Wed Oct 23 14:55:37 2019 +0200

        Make tests work after the changes introduced in #3793 (#3874)

        * Make tests work after the changes introduced in #3793

        * Remove unneccessary import

    commit bce6d804aa86504599ff912387295c58f846cbf3
    Author: Jim Posen <jim.posen@gmail.com>
    Date:   Thu Oct 10 12:18:58 2019 +0200

        Logic for checking Substrate proofs from within runtime module. (#3783)

    commit a7013e94b6c772c1d45a7cacbb445f73f6554fca
    Author: Hernando Castano <castano.ha@gmail.com>
    Date:   Fri Oct 4 15:21:00 2019 +0300

        Allow tracking of multiple bridges

    commit 3cf648242d631e32bd553a67df54bf5a48912839
    Author: Hernando Castano <castano.ha@gmail.com>
    Date:   Tue Oct 1 14:55:04 2019 +0200

        Add BridgeId => Bridge mapping

    commit 001c74c45072213e01857d0a2454379b447c5a76
    Author: Hernando Castano <castano.ha@gmail.com>
    Date:   Tue Oct 1 11:10:19 2019 +0200

        Get the mock runtime for tests set up

    commit 38443a1e8b424ed2f148eb95121d009f730e3b5a
    Author: Hernando Castano <castano.ha@gmail.com>
    Date:   Fri Sep 27 14:52:53 2019 +0200

        Clean up some warnings

    commit bdc3b01401e89c7111f8bf71f84c50750d25089f
    Author: Hernando Castano <castano.ha@gmail.com>
    Date:   Thu Sep 26 16:41:01 2019 +0200

        Add more skeleton code

    commit 26995efbf4bac2842eb2822322f7ad3c3e88feb8
    Author: Hernando Castano <castano.ha@gmail.com>
    Date:   Wed Sep 25 15:16:57 2019 +0200

        Create `bridge` module skeleton

commit bfd30ef8363b1483ef1107ae1eb958a4e944c93b
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Tue Dec 10 12:10:53 2019 +0300

    actually use signer from CLI to sign Substrate transactions

commit 504028eac60d9d14ba95b506cd355b0d2f405ce0
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Tue Dec 10 12:02:22 2019 +0300

    go offline for a bit on connection error

commit 446d0c8d20187dfd1beb173958ea28f2ad97887d
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Tue Dec 10 11:25:50 2019 +0300

    enable info logs by default

commit d039c60ec72bc91adfdad85442bc99a93b7f8e8d
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Tue Dec 10 11:12:51 2019 +0300

    support basic CLI arguments

commit 65c6d48e23576f36e8541878b920a03730226392
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Mon Dec 9 15:37:48 2019 +0300

    fix restart

commit 96e94c1c4b22d732078f8c401b872c5f8246c3fe
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Mon Dec 9 14:57:53 2019 +0300

    license

commit 68f4191e6cdd211ac8975e0b79f8a6f46a3ca953
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Mon Dec 9 14:56:05 2019 +0300

    restart sync when Substrate reorgs && we are unlucky

commit 29887c446167d580d73cc03a0b71c31890cafb51
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Mon Dec 9 13:49:31 2019 +0300

    only read genesis hash once

commit 832492b8393fe2063adf9c58c2b9e060dc3e4efb
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Mon Dec 9 13:23:26 2019 +0300

    changed TODO

commit 9dbc130e5fa036ae63d973819daf30f4ed6ffb5b
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Mon Dec 9 13:16:56 2019 +0300

    removed obsolete exit future

commit d03408cd8284eb0c61e7e96429b4f6199353e030
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Mon Dec 9 13:16:17 2019 +0300

    removed obsolete TODOs + moved a couple of TODOs to runtime module

commit ed8bec44b79f9a2ce829e59f10181368b2f42139
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Mon Dec 9 12:37:05 2019 +0300

    explained TODO fix

commit aa9c4c66ec2904eeb6072d654718b0ac0b7d8803
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Mon Dec 9 12:28:09 2019 +0300

    fix tx outcome serialization

commit 126f8f5484dac8c4af588ae86dc8855919d6c822
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Mon Dec 9 12:05:05 2019 +0300

    prune old ethereum headers when Substrate best header is too far in the future

commit c7bd301e631a44fe3263e188d0956081aa84f31e
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Fri Dec 6 12:51:50 2019 +0300

    fix trace

commit 549bb7acdb30cfdafe6c8600f0410212539ea63d
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Fri Dec 6 12:51:26 2019 +0300

    tx hashes are already a part of Block response

commit 7864017909f87ea36955d605a924c3c88bc88df3
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Thu Dec 5 12:29:37 2019 +0300

    submit bunch of headers at once + some fixes

commit 96485f85d38c144f0771f02ba692216a60356665
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Wed Dec 4 17:22:13 2019 +0300

    print status messages

commit ae0ec4c087136db653339537daab7f96a8c21b65
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Wed Dec 4 17:06:00 2019 +0300

    continue actual Substrate client implementation

commit 8146293740d70b88904568ff8e5acdfbadf06fd3
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Wed Dec 4 13:49:30 2019 +0300

    fix IncompleteHeader condition

commit 767c6201157dabcccf7f62e643681ca298224fb1
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Wed Dec 4 10:55:06 2019 +0300

    actual Substrate client implementation

commit 221fd4ccd2b1eea12c9dacf800d80e15ec115c1b
Author: Svyatoslav Nikolsky <svyatonik@gmail.com>
Date:   Wed Nov 20 17:28:13 2019 +0300

    initial commit

bridges/relays/ethereum/src/substrate_client.rs

@@ -0,0 +1,320 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Parity-Bridge.
+
+// Parity-Bridge 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-Bridge 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-Bridge.  If not, see <http://www.gnu.org/licenses/>.
+
+use codec::{Encode, Decode};
+use jsonrpsee_core::{client::ClientError, common::Params};
+use jsonrpsee_http::{HttpClient, RequestError, http_client};
+use serde_json::{from_value, to_value};
+use sp_core::crypto::Pair;
+use sp_runtime::traits::IdentifyAccount;
+use crate::ethereum_sync_loop::MaybeConnectionError;
+use crate::ethereum_types::{
+	Bytes,
+	H256,
+	HeaderId as EthereumHeaderId,
+	QueuedHeader as QueuedEthereumHeader,
+};
+use crate::substrate_types::{
+	TransactionHash,
+	into_substrate_ethereum_header,
+	into_substrate_ethereum_receipts,
+};
+
+/// Substrate client type.
+pub struct Client {
+	/// Substrate RPC client.
+	rpc_client: HttpClient,
+	/// Transactions signer.
+	signer: sp_core::sr25519::Pair,
+	/// Genesis block hash.
+	genesis_hash: Option<H256>,
+}
+
+/// All possible errors that can occur during interacting with Ethereum node.
+#[derive(Debug)]
+pub enum Error {
+	/// Request start failed.
+	StartRequestFailed(RequestError),
+	/// Request not found (should never occur?).
+	RequestNotFound,
+	/// Failed to receive response.
+	ResponseRetrievalFailed(ClientError<RequestError>),
+	/// Failed to parse response.
+	ResponseParseFailed,
+}
+
+impl MaybeConnectionError for Error {
+	fn is_connection_error(&self) -> bool {
+		match *self {
+			Error::StartRequestFailed(_) | Error::ResponseRetrievalFailed(_) => true,
+			_ => false,
+		}
+	}
+}
+
+/// Returns client that is able to call RPCs on Substrate node.
+pub fn client(uri: &str, signer: sp_core::sr25519::Pair) -> Client {
+	Client {
+		rpc_client: http_client(uri),
+		signer,
+		genesis_hash: None,
+	}
+}
+
+/// Returns best Ethereum block that Substrate runtime knows of.
+pub async fn best_ethereum_block(client: Client) -> (Client, Result<EthereumHeaderId, Error>) {
+	let (client, result) = call_rpc::<(u64, H256)>(
+		client,
+		"state_call",
+		Params::Array(vec![
+			to_value("EthereumHeadersApi_best_block").unwrap(),
+			to_value("0x").unwrap(),
+		]),
+	).await;
+	(client, result.map(|(num, hash)| EthereumHeaderId(num, hash)))
+}
+
+/// Returns true if transactions receipts are required for Ethereum header submission.
+pub async fn ethereum_receipts_required(
+	client: Client,
+	header: QueuedEthereumHeader,
+) -> (Client, Result<(EthereumHeaderId, bool), Error>) {
+	let id = header.id();
+	let header = into_substrate_ethereum_header(header.header());
+	let encoded_header = header.encode();
+	let (client, receipts_required) = call_rpc(
+		client,
+		"state_call",
+		Params::Array(vec![
+			to_value("EthereumHeadersApi_is_import_requires_receipts").unwrap(),
+			to_value(Bytes(encoded_header)).unwrap(),
+		]),
+	).await;
+	(client, receipts_required.map(|receipts_required| (id, receipts_required)))
+}
+
+/// Returns true if Ethereum header is known to Substrate runtime.
+pub async fn ethereum_header_known(
+	client: Client,
+	id: EthereumHeaderId,
+) -> (Client, Result<(EthereumHeaderId, bool), Error>) {
+	// Substrate module could prune old headers. So this fn could return false even
+	// if header is synced. And we'll mark corresponding Ethereum header as Orphan.
+	//
+	// But when we'll read best header from Substrate next time, we will know that
+	// there's a better header => this Orphan will either be marked as synced, or
+	// eventually pruned.
+	let encoded_id = id.1.encode();
+	let (client, is_known_block) = call_rpc(
+		client,
+		"state_call",
+		Params::Array(vec![
+			to_value("EthereumHeadersApi_is_known_block").unwrap(),
+			to_value(Bytes(encoded_id)).unwrap(),
+		]),
+	).await;
+	(client, is_known_block.map(|is_known_block| (id, is_known_block)))
+}
+
+/// Submits Ethereum header to Substrate runtime.
+pub async fn submit_ethereum_headers(
+	client: Client,
+	headers: Vec<QueuedEthereumHeader>,
+) -> (Client, Result<(TransactionHash, Vec<EthereumHeaderId>), Error>) {
+	let ids = headers.iter().map(|header| header.id()).collect();
+	let (client, genesis_hash) = match client.genesis_hash {
+		Some(genesis_hash) => (client, genesis_hash),
+		None => {
+			let (mut client, genesis_hash) = block_hash_by_number(client, 0).await;
+			let genesis_hash = match genesis_hash {
+				Ok(genesis_hash) => genesis_hash,
+				Err(err) => return (client, Err(err)),
+			};
+			client.genesis_hash = Some(genesis_hash);
+			(client, genesis_hash)
+		},
+	};
+	let account_id = client.signer.public().as_array_ref().clone().into();
+	let (client, nonce) = next_account_index(client, account_id).await;
+	let nonce = match nonce {
+		Ok(nonce) => nonce,
+		Err(err) => return (client, Err(err)),
+	};
+	let transaction = create_submit_transaction(
+		headers,
+		&client.signer,
+		nonce,
+		genesis_hash,
+	);
+	let encoded_transaction = transaction.encode();
+	let (client, transaction_hash) = call_rpc(
+		client,
+		"author_submitExtrinsic",
+		Params::Array(vec![
+			to_value(Bytes(encoded_transaction)).unwrap(),
+		]),
+	).await;
+	(client, transaction_hash.map(|transaction_hash| (transaction_hash, ids)))
+}
+
+/// Get Substrate block hash by its number.
+async fn block_hash_by_number(client: Client, number: u64) -> (Client, Result<H256, Error>) {
+	call_rpc(
+		client,
+		"chain_getBlockHash",
+		Params::Array(vec![
+			to_value(number).unwrap(),
+		]),
+	).await
+}
+
+/// Get substrate account nonce.
+async fn next_account_index(
+	client: Client,
+	account: node_primitives::AccountId,
+) -> (Client, Result<node_primitives::Index, Error>) {
+	use sp_core::crypto::Ss58Codec;
+
+	let (client, index) = call_rpc_u64(
+		client,
+		"system_accountNextIndex",
+		Params::Array(vec![
+			to_value(account.to_ss58check()).unwrap(),
+		]),
+	).await;
+	(client, index.map(|index| index as _))
+}
+
+/// Calls RPC on Substrate node that returns Bytes.
+async fn call_rpc<T: Decode>(
+	mut client: Client,
+	method: &'static str,
+	params: Params,
+) -> (Client, Result<T, Error>) {
+	async fn do_call_rpc<T: Decode>(
+		client: &mut Client,
+		method: &'static str,
+		params: Params,
+	) -> Result<T, Error> {
+		let request_id = client
+			.rpc_client
+			.start_request(method, params)
+			.await
+			.map_err(Error::StartRequestFailed)?;
+		// WARN: if there'll be need for executing >1 request at a time, we should avoid
+		// calling request_by_id
+		let response = client
+			.rpc_client
+			.request_by_id(request_id)
+			.ok_or(Error::RequestNotFound)?
+			.await
+			.map_err(Error::ResponseRetrievalFailed)?;
+		let encoded_response: Bytes = from_value(response).map_err(|_| Error::ResponseParseFailed)?;
+		Decode::decode(&mut &encoded_response.0[..]).map_err(|_| Error::ResponseParseFailed)
+	}
+
+	let result = do_call_rpc(&mut client, method, params).await;
+	(client, result)
+}
+
+/// Calls RPC on Substrate node that returns u64.
+async fn call_rpc_u64(
+	mut client: Client,
+	method: &'static str,
+	params: Params,
+) -> (Client, Result<u64, Error>) {
+	async fn do_call_rpc(
+		client: &mut Client,
+		method: &'static str,
+		params: Params,
+	) -> Result<u64, Error> {
+		let request_id = client
+			.rpc_client
+			.start_request(method, params)
+			.await
+			.map_err(Error::StartRequestFailed)?;
+		// WARN: if there'll be need for executing >1 request at a time, we should avoid
+		// calling request_by_id
+		let response = client
+			.rpc_client
+			.request_by_id(request_id)
+			.ok_or(Error::RequestNotFound)?
+			.await
+			.map_err(Error::ResponseRetrievalFailed)?;
+		response.as_u64().ok_or(Error::ResponseParseFailed)
+	}
+
+	let result = do_call_rpc(&mut client, method, params).await;
+	(client, result)
+}
+
+/// Create Substrate transaction for submitting Ethereum header.
+fn create_submit_transaction(
+	headers: Vec<QueuedEthereumHeader>,
+	signer: &sp_core::sr25519::Pair,
+	index: node_primitives::Index,
+	genesis_hash: H256,
+) -> node_runtime::UncheckedExtrinsic {
+	let function = node_runtime::Call::BridgeEthPoa(
+		node_runtime::BridgeEthPoaCall::import_headers(
+			headers
+				.into_iter()
+				.map(|header| {
+					let (header, receipts) = header.extract();
+					(
+						into_substrate_ethereum_header(&header),
+						into_substrate_ethereum_receipts(&receipts),
+					)
+				})
+				.collect(),
+		),
+	);
+
+	let extra = |i: node_primitives::Index, f: node_primitives::Balance| {
+		(
+			frame_system::CheckVersion::<node_runtime::Runtime>::new(),
+			frame_system::CheckGenesis::<node_runtime::Runtime>::new(),
+			frame_system::CheckEra::<node_runtime::Runtime>::from(sp_runtime::generic::Era::Immortal),
+			frame_system::CheckNonce::<node_runtime::Runtime>::from(i),
+			frame_system::CheckWeight::<node_runtime::Runtime>::new(),
+			pallet_transaction_payment::ChargeTransactionPayment::<node_runtime::Runtime>::from(f),
+			Default::default(),
+		)
+	};
+	let raw_payload = node_runtime::SignedPayload::from_raw(
+		function,
+		extra(index, 0),
+		(
+			198, // VERSION.spec_version as u32,
+			genesis_hash,
+			genesis_hash,
+			(),
+			(),
+			(),
+			(),
+		),
+	);
+	let signature = raw_payload.using_encoded(|payload| signer.sign(payload));
+	let signer: sp_runtime::MultiSigner = signer.public().into();
+	let (function, extra, _) = raw_payload.deconstruct();
+
+	node_runtime::UncheckedExtrinsic::new_signed(
+		function,
+		signer.into_account().into(),
+		signature.into(),
+		extra,
+	)
+}