Submit (& sign) extrinsics from the runtime. (#3514)

* Abstract constructing extrinsic and signing.

* Initial impl of signer.

* Implement get payload.

* Clean up the code.

* Improve docs.

* Bump version.

* Update core/sr-primitives/src/generic/unchecked_extrinsic.rs

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* Fix tests & address grumbles.

* Fix build.

* Fix runtime tests.

* Fix bound test.

* Fix bound test.

substrate/node/runtime/src/lib.rs

@@ -39,7 +39,7 @@ use sr_primitives::{ApplyResult, impl_opaque_keys, generic, create_runtime_str,
 use sr_primitives::transaction_validity::TransactionValidity;
 use sr_primitives::weights::Weight;
 use sr_primitives::traits::{
-	BlakeTwo256, Block as BlockT, DigestFor, NumberFor, StaticLookup,
+	self, BlakeTwo256, Block as BlockT, DigestFor, NumberFor, StaticLookup, SaturatedConversion,
 };
 use version::RuntimeVersion;
 use elections::VoteIndex;
@@ -48,6 +48,7 @@ use version::NativeVersion;
 use primitives::OpaqueMetadata;
 use grandpa::{AuthorityId as GrandpaId, AuthorityWeight as GrandpaWeight};
 use im_online::sr25519::{AuthorityId as ImOnlineId};
+use system::offchain::TransactionSubmitter;
 
 #[cfg(any(feature = "std", test))]
 pub use sr_primitives::BuildStorage;
@@ -80,7 +81,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	// implementation changes and behavior does not, then leave spec_version as
 	// is and increment impl_version.
 	spec_version: 154,
-	impl_version: 157,
+	impl_version: 158,
 	apis: RUNTIME_API_VERSIONS,
 };
 
@@ -392,11 +393,13 @@ impl sudo::Trait for Runtime {
 	type Proposal = Call;
 }
 
+type SubmitTransaction = TransactionSubmitter<ImOnlineId, Runtime, UncheckedExtrinsic>;
+
 impl im_online::Trait for Runtime {
 	type AuthorityId = ImOnlineId;
 	type Call = Call;
 	type Event = Event;
-	type UncheckedExtrinsic = UncheckedExtrinsic;
+	type SubmitTransaction = SubmitTransaction;
 	type ReportUnresponsiveness = Offences;
 	type CurrentElectedSet = staking::CurrentElectedStashAccounts<Runtime>;
 }
@@ -424,6 +427,33 @@ impl finality_tracker::Trait for Runtime {
 	type ReportLatency = ReportLatency;
 }
 
+impl system::offchain::CreateTransaction<Runtime, UncheckedExtrinsic> for Runtime {
+	type Signature = Signature;
+
+	fn create_transaction<F: system::offchain::Signer<AccountId, Self::Signature>>(
+		call: Call,
+		account: AccountId,
+		index: Index,
+	) -> Option<(Call, <UncheckedExtrinsic as traits::Extrinsic>::SignaturePayload)> {
+		let period = 1 << 8;
+		let current_block = System::block_number().saturated_into::<u64>();
+		let tip = 0;
+		let extra: SignedExtra = (
+			system::CheckVersion::<Runtime>::new(),
+			system::CheckGenesis::<Runtime>::new(),
+			system::CheckEra::<Runtime>::from(generic::Era::mortal(period, current_block)),
+			system::CheckNonce::<Runtime>::from(index),
+			system::CheckWeight::<Runtime>::new(),
+			balances::TakeFees::<Runtime>::from(tip),
+		);
+		let raw_payload = SignedPayload::new(call, extra).ok()?;
+		let signature = F::sign(account.clone(), &raw_payload)?;
+		let address = Indices::unlookup(account);
+		let (call, extra, _) = raw_payload.deconstruct();
+		Some((call, (address, signature, extra)))
+	}
+}
+
 construct_runtime!(
 	pub enum Runtime where
 		Block = Block,
@@ -475,6 +505,8 @@ pub type SignedExtra = (
 );
 /// Unchecked extrinsic type as expected by this runtime.
 pub type UncheckedExtrinsic = generic::UncheckedExtrinsic<Address, Call, Signature, SignedExtra>;
+/// The payload being signed in transactions.
+pub type SignedPayload = generic::SignedPayload<Call, SignedExtra>;
 /// Extrinsic type that has already been checked.
 pub type CheckedExtrinsic = generic::CheckedExtrinsic<AccountId, Call, SignedExtra>;
 /// Executive: handles dispatch to the various modules.
@@ -609,3 +641,28 @@ impl_runtime_apis! {
 		}
 	}
 }
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use sr_primitives::app_crypto::RuntimeAppPublic;
+	use system::offchain::SubmitSignedTransaction;
+
+	fn is_submit_signed_transaction<T, Signer>(_arg: T) where
+		T: SubmitSignedTransaction<
+			Runtime,
+			Call,
+			Extrinsic=UncheckedExtrinsic,
+			CreateTransaction=Runtime,
+			Signer=Signer,
+		>,
+		Signer: RuntimeAppPublic + From<AccountId>,
+		Signer::Signature: Into<Signature>,
+	{}
+
+	#[test]
+	fn validate_bounds() {
+		let x = SubmitTransaction::default();
+		is_submit_signed_transaction(x);
+	}
+}