Claim yer sale DOTs (#97)

* Add claims. * Failing build * Updatee to latest substrate, fix tests * Remove unneeded * Introduce tests with real work sig * Use right 64 bytes of pubkey to get eth addr * Fix for eth sig * Fix build * Fix wasm
2026-05-30 10:31:03 +00:00 · 2019-01-25 08:43:05 +00:00
parent a05d422a55
commit c5bb21ab3c
13 changed files with 793 additions and 230 deletions
@@ -0,0 +1,278 @@
+// Copyright 2017-2018 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate 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.
+
+// Substrate 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 Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Module to process claims from Ethereum addresses.
+
+use rstd::prelude::*;
+use tiny_keccak::keccak256;
+use secp256k1;
+use srml_support::{StorageValue, StorageMap};
+use system::ensure_signed;
+use codec::Encode;
+#[cfg(feature = "std")]
+use sr_primitives::traits::Zero;
+use balances;
+
+/// Configuration trait.
+pub trait Trait: balances::Trait {
+	/// The overarching event type.
+	type Event: From<Event<Self>> + Into<<Self as system::Trait>::Event>;
+}
+
+type EthereumAddress = [u8; 20];
+type EcdsaSignature = ([u8; 32], [u8; 32], i8);
+
+/// An event in this module.
+decl_event!(
+	pub enum Event<T> where
+		B = <T as balances::Trait>::Balance,
+		A = <T as system::Trait>::AccountId
+	{
+		/// Someone claimed some DOTs.
+		Claimed(A, EthereumAddress, B),
+	}
+);
+
+decl_storage! {
+	// A macro for the Storage trait, and its implementation, for this module.
+	// This allows for type-safe usage of the Substrate storage database, so you can
+	// keep things around between blocks.
+	trait Store for Module<T: Trait> as Claims {
+		Claims get(claims) build(|config: &GenesisConfig<T>| {
+			config.claims.iter().map(|(a, b)| (a.clone(), b.clone())).collect::<Vec<_>>()
+		}): map EthereumAddress => Option<T::Balance>;
+		Total get(total) build(|config: &GenesisConfig<T>| {
+			config.claims.iter().fold(Zero::zero(), |acc: T::Balance, &(_, n)| acc + n)
+		}): T::Balance;
+	}
+	add_extra_genesis {
+		config(claims): Vec<(EthereumAddress, T::Balance)>;
+	}
+}
+
+fn ecdsa_recover(sig: &EcdsaSignature, msg: &[u8; 32]) -> Option<[u8; 64]> {
+	let v = secp256k1::RecoveryId::parse(if sig.2 > 26 { sig.2 - 27 } else { sig.2 } as u8).ok()?;
+	let rs = (sig.0, sig.1).using_encoded(secp256k1::Signature::parse_slice).ok()?;
+	let pubkey = secp256k1::recover(&secp256k1::Message::parse(msg), &rs, &v).ok()?;
+	let mut res = [0u8; 64];
+	res.copy_from_slice(&pubkey.serialize()[1..65]);
+	Some(res)
+}
+
+fn create_msg(who: &[u8]) -> Vec<u8> {
+	let prefix = b"Pay DOTs to the Polkadot account:";
+	let mut l = prefix.len() + who.len();
+	let mut rev = Vec::new();
+	while l > 0 {
+		rev.push(b'0' + (l % 10) as u8);
+		l /= 10;
+	}
+	let mut v = b"\x19Ethereum Signed Message:\n".to_vec();
+	v.extend(rev.into_iter().rev());
+	v.extend_from_slice(&prefix[..]);
+	v.extend_from_slice(who);
+	v
+}
+
+fn eth_recover(s: &EcdsaSignature, who: &[u8]) -> Option<EthereumAddress> {
+	let msg = keccak256(&create_msg(who));
+	let mut res = EthereumAddress::default();
+	res.copy_from_slice(&keccak256(&ecdsa_recover(s, &msg)?[..])[12..]);
+	Some(res)
+}
+
+decl_module! {
+	pub struct Module<T: Trait> for enum Call where origin: T::Origin {
+		/// Deposit one of this module's events by using the default implementation.
+		fn deposit_event<T>() = default;
+
+		/// Make a claim.
+		fn claim(origin, ethereum_signature: EcdsaSignature) {
+			// This is a public call, so we ensure that the origin is some signed account.
+			let sender = ensure_signed(origin)?;
+			
+			let signer = sender.using_encoded(|data|
+					eth_recover(&ethereum_signature, data)
+				).ok_or("Invalid Ethereum signature")?;
+			
+			let balance_due = <Claims<T>>::take(&signer)
+				.ok_or("Ethereum address has no claim")?;
+			
+			<Total<T>>::mutate(|t| if *t < balance_due {
+				panic!("Logic error: Pot less than the total of claims!")
+			} else {
+				*t -= balance_due
+			});
+
+			<balances::Module<T>>::increase_free_balance_creating(&sender, balance_due);
+
+			// Let's deposit an event to let the outside world know this happened.
+			Self::deposit_event(RawEvent::Claimed(sender, signer, balance_due));
+		}
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use secp256k1;
+	use tiny_keccak::keccak256;
+	use super::*;
+
+	use sr_io::{self as runtime_io, with_externalities};
+	use substrate_primitives::{H256, Blake2Hasher, hexdisplay::HexDisplay};
+	use codec::{Decode, Encode};
+	// The testing primitives are very useful for avoiding having to work with signatures
+	// or public keys. `u64` is used as the `AccountId` and no `Signature`s are requried.
+	use sr_primitives::{
+		BuildStorage, traits::{BlakeTwo256, IdentityLookup}, testing::{Digest, DigestItem, Header}
+	};
+	use balances;
+
+	impl_outer_origin! {
+		pub enum Origin for Test {}
+	}
+
+	// For testing the module, we construct most of a mock runtime. This means
+	// first constructing a configuration type (`Test`) which `impl`s each of the
+	// configuration traits of modules we want to use.
+	#[derive(Clone, Eq, PartialEq)]
+	pub struct Test;
+	impl system::Trait for Test {
+		type Origin = Origin;
+		type Index = u64;
+		type BlockNumber = u64;
+		type Hash = H256;
+		type Hashing = BlakeTwo256;
+		type Digest = Digest;
+		type AccountId = u64;
+		type Lookup = IdentityLookup<u64>;
+		type Header = Header;
+		type Event = ();
+		type Log = DigestItem;
+	}
+	impl balances::Trait for Test {
+		type Balance = u64;
+		type OnFreeBalanceZero = ();
+		type OnNewAccount = ();
+		type EnsureAccountLiquid = ();
+		type Event = ();
+	}
+	impl Trait for Test {
+		type Event = ();
+	}
+	type Balances = balances::Module<Test>;
+	type Claims = Module<Test>;
+
+	fn alice_secret() -> secp256k1::SecretKey {
+		secp256k1::SecretKey::parse(&keccak256(b"Alice")).unwrap()
+	}
+	fn alice_public() -> secp256k1::PublicKey {
+		secp256k1::PublicKey::from_secret_key(&alice_secret())
+	}
+	fn alice_eth() -> EthereumAddress {
+		let mut res = EthereumAddress::default();
+		res.copy_from_slice(&keccak256(&alice_public().serialize()[1..65])[12..]);
+		res
+	}
+	fn alice_sig(who: &[u8]) -> EcdsaSignature {
+		let msg = keccak256(&create_msg(who));
+		let (sig, recovery_id) = secp256k1::sign(&secp256k1::Message::parse(&msg), &alice_secret()).unwrap();
+		let sig: ([u8; 32], [u8; 32]) = Decode::decode(&mut &sig.serialize()[..]).unwrap();
+		(sig.0, sig.1, recovery_id.serialize() as i8)
+	}
+	fn bob_secret() -> secp256k1::SecretKey {
+		secp256k1::SecretKey::parse(&keccak256(b"Bob")).unwrap()
+	}
+	fn bob_public() -> secp256k1::PublicKey {
+		secp256k1::PublicKey::from_secret_key(&bob_secret())
+	}
+	fn bob_eth() -> EthereumAddress {
+		let mut res = EthereumAddress::default();
+		res.copy_from_slice(&keccak256(&bob_public().serialize()[1..65])[12..]);
+		res
+	}
+	fn bob_sig(who: &[u8]) -> EcdsaSignature {
+		let msg = keccak256(&create_msg(who));
+		let (sig, recovery_id) = secp256k1::sign(&secp256k1::Message::parse(&msg), &bob_secret()).unwrap();
+		let sig: ([u8; 32], [u8; 32]) = Decode::decode(&mut &sig.serialize()[..]).unwrap();
+		(sig.0, sig.1, recovery_id.serialize() as i8)
+	}
+
+	// This function basically just builds a genesis storage key/value store according to
+	// our desired mockup.
+	fn new_test_ext() -> sr_io::TestExternalities<Blake2Hasher> {
+		let mut t = system::GenesisConfig::<Test>::default().build_storage().unwrap().0;
+		// We use default for brevity, but you can configure as desired if needed.
+		t.extend(balances::GenesisConfig::<Test>::default().build_storage().unwrap().0);
+		t.extend(GenesisConfig::<Test>{
+			claims: vec![(alice_eth(), 100)],
+		}.build_storage().unwrap().0);
+		t.into()
+	}
+
+	#[test]
+	fn basic_setup_works() {
+		with_externalities(&mut new_test_ext(), || {
+			assert_eq!(Claims::total(), 100);
+			assert_eq!(Claims::claims(&alice_eth()), Some(100));
+			assert_eq!(Claims::claims(&[0; 20]), None);
+		});
+	}
+
+	#[test]
+	fn claiming_works() {
+		with_externalities(&mut new_test_ext(), || {
+			assert_eq!(Balances::free_balance(&42), 0);
+			assert_ok!(Claims::claim(Origin::signed(42), alice_sig(&42u64.encode())));
+			assert_eq!(Balances::free_balance(&42), 100);
+		});
+	}
+
+	#[test]
+	fn double_claiming_doesnt_work() {
+		with_externalities(&mut new_test_ext(), || {
+			assert_eq!(Balances::free_balance(&42), 0);
+			assert_ok!(Claims::claim(Origin::signed(42), alice_sig(&42u64.encode())));
+			assert_noop!(Claims::claim(Origin::signed(42), alice_sig(&42u64.encode())), "Ethereum address has no claim");
+		});
+	}
+
+	#[test]
+	fn non_sender_sig_doesnt_work() {
+		with_externalities(&mut new_test_ext(), || {
+			assert_eq!(Balances::free_balance(&42), 0);
+			assert_noop!(Claims::claim(Origin::signed(42), alice_sig(&69u64.encode())), "Ethereum address has no claim");
+		});
+	}
+
+	#[test]
+	fn non_claimant_doesnt_work() {
+		with_externalities(&mut new_test_ext(), || {
+			assert_eq!(Balances::free_balance(&42), 0);
+			assert_noop!(Claims::claim(Origin::signed(42), bob_sig(&69u64.encode())), "Ethereum address has no claim");
+		});
+	}
+
+	#[test]
+	fn real_eth_sig_works() {
+		let sig = hex!["7505f2880114da51b3f5d535f8687953c0ab9af4ab81e592eaebebf53b728d2b6dfd9b5bcd70fee412b1f31360e7c2774009305cb84fc50c1d0ff8034dfa5fff1c"];
+		let sig = EcdsaSignature::decode(&mut &sig[..]).unwrap();
+		let who = 42u64.encode();
+		let msg = create_msg(&who);
+		let signer = eth_recover(&sig, &who).unwrap();
+		assert_eq!(signer, hex!["DF67EC7EAe23D2459694685257b6FC59d1BAA1FE"]);
+	}
+}