Verify signature and session index during apply phase of im-online.

core/sr-primitives/src/traits.rs

@@ -874,6 +874,14 @@ pub trait SignedExtension:
 	fn additional_signed(&self) -> Result<Self::AdditionalSigned, &'static str>;
 
 	/// Validate a signed transaction for the transaction queue.
+	///
+	/// This function can be called frequently by the transaction queue,
+	/// to obtain transaction validity against current state.
+	/// It should perform all checks that determine a valid transaction,
+	/// that can pay for it's execution and quickly eliminate ones
+	/// that are stale or incorrect.
+	///
+	/// Make sure to perform the same checks in `pre_dispatch` function.
 	fn validate(
 		&self,
 		_who: &Self::AccountId,
@@ -885,6 +893,13 @@ pub trait SignedExtension:
 	}
 
 	/// Do any pre-flight stuff for a signed transaction.
+	///
+	/// Note this function by default delegates to `validate`, so that
+	/// all checks performed for the transaction queue are also performed during
+	/// the dispatch phase (applying the extrinsic).
+	///
+	/// If you ever override this function, you need to make sure to always
+	/// perform the same validation as in `validate`.
 	fn pre_dispatch(
 		self,
 		who: &Self::AccountId,
@@ -895,16 +910,31 @@ pub trait SignedExtension:
 		self.validate(who, call, info, len).map(|_| Self::Pre::default())
 	}
 
-	/// Validate an unsigned transaction for the transaction queue. Normally the default
-	/// implementation is fine since `ValidateUnsigned` is a better way of recognising and
-	/// validating unsigned transactions.
+	/// Validate an unsigned transaction for the transaction queue.
+	///
+	/// Normally the default implementation is fine since `ValidateUnsigned`
+	/// is a better way of recognising and validating unsigned transactions.
+	///
+	/// This function can be called frequently by the transaction queue,
+	/// to obtain transaction validity against current state.
+	/// It should perform all checks that determine a valid unsigned transaction,
+	/// and quickly eliminate ones that are stale or incorrect.
+	///
+	/// Make sure to perform the same checks in `pre_dispatch_unsigned` function.
 	fn validate_unsigned(
 		_call: &Self::Call,
 		_info: DispatchInfo,
 		_len: usize,
 	) -> Result<ValidTransaction, DispatchError> { Ok(Default::default()) }
 
 	/// Do any pre-flight stuff for a unsigned transaction.
+	///
+	/// Note this function by default delegates to `validate_unsigned`, so that
+	/// all checks performed for the transaction queue are also performed during
+	/// the dispatch phase (applying the extrinsic).
+	///
+	/// If you ever override this function, you need to make sure to always
+	/// perform the same validation as in `validate_unsigned`.
 	fn pre_dispatch_unsigned(
 		call: &Self::Call,
 		info: DispatchInfo,
@@ -1095,7 +1125,12 @@ pub trait RuntimeApiInfo {
 	const VERSION: u32;
 }
 
-/// Something that can validate unsigned extrinsics.
+/// Something that can validate unsigned extrinsics for the transaction pool.
+///
+/// Note that any checks done here are only used for determining the validity of
+/// the transaction for the transaction pool.
+/// During block execution phase one need to perform the same checks anyway,
+/// since this function is not being called.
 pub trait ValidateUnsigned {
 	/// The call to validate
 	type Call;

node/runtime/src/lib.rs

@@ -81,7 +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: 144,
-	impl_version: 144,
+	impl_version: 145,
 	apis: RUNTIME_API_VERSIONS,
 };
 

srml/im-online/src/lib.rs

@@ -77,7 +77,7 @@ use rstd::prelude::*;
 use session::SessionIndex;
 use sr_io::Printable;
 use srml_support::{
-	StorageValue, decl_module, decl_event, decl_storage, StorageDoubleMap, print,
+	StorageValue, decl_module, decl_event, decl_storage, StorageDoubleMap, print, ensure
 };
 use system::ensure_none;
 use app_crypto::RuntimeAppPublic;
@@ -206,18 +206,24 @@ decl_module! {
 		fn heartbeat(
 			origin,
 			heartbeat: Heartbeat<T::BlockNumber>,
-			_signature: AuthoritySignature
+			signature: AuthoritySignature
 		) {
 			ensure_none(origin)?;
 
 			let current_session = <session::Module<T>>::current_index();
+			ensure!(current_session == heartbeat.session_index, "Outdated hearbeat received.");
 			let exists = <ReceivedHeartbeats>::exists(
 				&current_session,
 				&heartbeat.authority_index
 			);
 			let keys = Keys::get();
 			let public = keys.get(heartbeat.authority_index as usize);
 			if let (true, Some(public)) = (!exists, public) {
+				let signature_valid = heartbeat.using_encoded(|encoded_heartbeat| {
+					public.verify(&encoded_heartbeat, &signature)
+				});
+				ensure!(signature_valid, "Invalid hearbeat signature.");
+
 				Self::deposit_event(Event::HeartbeatReceived(public.clone()));
 
 				let network_state = heartbeat.network_state.encode();