Expose block random seed and timestamp to contract ABI (#1630)

* Expose block random seed and timestamp to contract ABI

* Add tests

* Bump spec version

substrate/Cargo.lock

@@ -3124,8 +3124,10 @@ dependencies = [
  "sr-sandbox 0.1.0",
  "sr-std 0.1.0",
  "srml-balances 0.1.0",
+ "srml-consensus 0.1.0",
  "srml-support 0.1.0",
  "srml-system 0.1.0",
+ "srml-timestamp 0.1.0",
  "substrate-primitives 0.1.0",
  "wabt 0.7.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

substrate/node/runtime/src/lib.rs

@@ -65,8 +65,8 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: create_runtime_str!("node"),
 	impl_name: create_runtime_str!("substrate-node"),
 	authoring_version: 10,
-	spec_version: 22,
-	impl_version: 22,
+	spec_version: 23,
+	impl_version: 23,
 	apis: RUNTIME_API_VERSIONS,
 };
 

substrate/node/runtime/wasm/Cargo.lock

@@ -1201,6 +1201,7 @@ dependencies = [
  "srml-balances 0.1.0",
  "srml-support 0.1.0",
  "srml-system 0.1.0",
+ "srml-timestamp 0.1.0",
  "substrate-primitives 0.1.0",
 ]
 

substrate/srml/contract/COMPLEXITY.md

@@ -281,6 +281,18 @@ This function serializes the address of the caller into the scratch buffer.
 
 **complexity**: Assuming that the address is of constant size, this function has constant complexity.
 
+## ext_random_seed
+
+This function serializes the current block's random seed into the scratch buffer.
+
+**complexity**: Assuming that the random seed is of constant size, this function has constant complexity.
+
+## ext_now
+
+This function serializes the current block's timestamp into the scratch buffer.
+
+**complexity**: Assuming that the timestamp is of constant size, this function has constant complexity.
+
 ## ext_input_size
 
 **complexity**: This function is of constant complexity.

substrate/srml/contract/Cargo.toml

@@ -18,11 +18,13 @@ sandbox = { package = "sr-sandbox", path = "../../core/sr-sandbox", default-feat
 srml-support = { path = "../support", default-features = false }
 system = { package = "srml-system", path = "../system", default-features = false }
 balances = { package = "srml-balances", path = "../balances", default-features = false }
+timestamp = { package = "srml-timestamp", path = "../timestamp", default-features = false }
 
 [dev-dependencies]
 wabt = "~0.7.4"
 assert_matches = "1.1"
 hex-literal = "0.1.0"
+consensus = { package = "srml-consensus", path = "../consensus", default-features = false }
 
 [features]
 default = ["std"]
@@ -38,6 +40,7 @@ std = [
 	"sandbox/std",
 	"srml-support/std",
 	"system/std",
+	"timestamp/std",
 	"parity-wasm/std",
 	"pwasm-utils/std",
 ]

substrate/srml/contract/src/exec.rs

@@ -21,10 +21,13 @@ use crate::gas::{GasMeter, Token, approx_gas_for_balance};
 use balances::{self, EnsureAccountLiquid};
 use rstd::prelude::*;
 use runtime_primitives::traits::{CheckedAdd, CheckedSub, Zero};
+use timestamp;
 
 pub type BalanceOf<T> = <T as balances::Trait>::Balance;
 pub type AccountIdOf<T> = <T as system::Trait>::AccountId;
 pub type CallOf<T> = <T as Trait>::Call;
+pub type MomentOf<T> = <T as timestamp::Trait>::Moment;
+pub type SeedOf<T> = <T as system::Trait>::Hash;
 
 #[cfg_attr(test, derive(Debug))]
 pub struct InstantiateReceipt<AccountId> {
@@ -95,6 +98,12 @@ pub trait Ext {
 
 	/// Returns the value transfered along with this call or as endowment.
 	fn value_transferred(&self) -> BalanceOf<Self::T>;
+
+	/// Returns a reference to the timestamp of the current block
+	fn now(&self) -> &MomentOf<Self::T>;
+
+	/// Returns a reference to the random seed for the current block
+	fn random_seed(&self) -> &SeedOf<Self::T>;
 }
 
 /// Loader is a companion of the `Vm` trait. It loads an appropriate abstract
@@ -311,6 +320,8 @@ where
 							ctx: &mut nested,
 							caller: self.self_account.clone(),
 							value_transferred: value,
+							timestamp: timestamp::Module::<T>::now(),
+							random_seed: system::Module::<T>::random_seed(),
 						},
 						input_data,
 						empty_output_buf,
@@ -382,6 +393,8 @@ where
 						ctx: &mut nested,
 						caller: self.self_account.clone(),
 						value_transferred: endowment,
+						timestamp: timestamp::Module::<T>::now(),
+						random_seed: system::Module::<T>::random_seed(),
 					},
 					input_data,
 					EmptyOutputBuf::new(),
@@ -528,6 +541,8 @@ struct CallContext<'a, 'b: 'a, T: Trait + 'b, V: Vm<T> + 'b, L: Loader<T>> {
 	ctx: &'a mut ExecutionContext<'b, T, V, L>,
 	caller: T::AccountId,
 	value_transferred: T::Balance,
+	timestamp: T::Moment,
+	random_seed: T::Hash,
 }
 
 impl<'a, 'b: 'a, T, E, V, L> Ext for CallContext<'a, 'b, T, V, L>
@@ -592,6 +607,14 @@ where
 	fn value_transferred(&self) -> T::Balance {
 		self.value_transferred
 	}
+
+	fn random_seed(&self) -> &T::Hash {
+		&self.random_seed
+	}
+
+	fn now(&self) -> &T::Moment {
+		&self.timestamp
+	}
 }
 
 /// These tests exercise the executive layer.

substrate/srml/contract/src/lib.rs

@@ -81,6 +81,7 @@ use runtime_support::dispatch::{Result, Dispatchable};
 use runtime_support::{Parameter, StorageMap, StorageValue, StorageDoubleMap};
 use system::{ensure_signed, RawOrigin};
 use runtime_io::{blake2_256, twox_128};
+use timestamp;
 
 pub type CodeHash<T> = <T as system::Trait>::Hash;
 
@@ -94,7 +95,7 @@ pub trait ComputeDispatchFee<Call, Balance> {
 	fn compute_dispatch_fee(call: &Call) -> Balance;
 }
 
-pub trait Trait: balances::Trait {
+pub trait Trait: balances::Trait + timestamp::Trait {
 	/// The outer call dispatch type.
 	type Call: Parameter + Dispatchable<Origin=<Self as system::Trait>::Origin>;
 

substrate/srml/contract/src/tests.rs

@@ -20,14 +20,14 @@
 #![allow(unused)]
 
 use runtime_io::with_externalities;
-use runtime_primitives::testing::{Digest, DigestItem, H256, Header};
+use runtime_primitives::testing::{Digest, DigestItem, H256, Header, UintAuthorityId};
 use runtime_primitives::traits::{BlakeTwo256, IdentityLookup};
 use runtime_primitives::BuildStorage;
 use runtime_io;
 use runtime_support::{StorageMap, StorageDoubleMap};
 use substrate_primitives::{Blake2Hasher};
 use system::{self, Phase, EventRecord};
-use {wabt, balances};
+use {wabt, balances, consensus};
 use hex_literal::*;
 use assert_matches::assert_matches;
 use crate::{
@@ -78,6 +78,15 @@ impl balances::Trait for Test {
 	type EnsureAccountLiquid = ();
 	type Event = MetaEvent;
 }
+impl timestamp::Trait for Test {
+	type Moment = u64;
+	type OnTimestampSet = ();
+}
+impl consensus::Trait for Test {
+	type Log = DigestItem;
+	type SessionKey = UintAuthorityId;
+	type InherentOfflineReport = ();
+}
 impl Trait for Test {
 	type Call = Call;
 	type Gas = u64;

substrate/srml/contract/src/wasm/mod.rs

@@ -203,6 +203,7 @@ mod tests {
 		transfers: Vec<TransferEntry>,
 		dispatches: Vec<DispatchEntry>,
 		next_account_id: u64,
+		random_seed: H256,
 	}
 	impl Ext for MockExt {
 		type T = Test;
@@ -266,6 +267,14 @@ mod tests {
 		fn value_transferred(&self) -> u64 {
 			1337
 		}
+
+		fn now(&self) -> &u64 {
+			&1111
+		}
+
+		fn random_seed(&self) -> &H256{
+			&self.random_seed
+		}
 	}
 
 	fn execute<E: Ext>(
@@ -1011,7 +1020,6 @@ mod tests {
 )
 "#;
 
-
 	#[test]
 	fn return_from_start_fn() {
 		let mut mock_ext = MockExt::default();
@@ -1027,4 +1035,134 @@ mod tests {
 
 		assert_eq!(output_data, vec![1, 2, 3, 4]);
 	}
+
+	const CODE_TIMESTAMP_NOW: &str = r#"
+(module
+	(import "env" "ext_now" (func $ext_now))
+	(import "env" "ext_scratch_size" (func $ext_scratch_size (result i32)))
+	(import "env" "ext_scratch_copy" (func $ext_scratch_copy (param i32 i32 i32)))
+	(import "env" "memory" (memory 1 1))
+
+	(func $assert (param i32)
+		(block $ok
+			(br_if $ok
+				(get_local 0)
+			)
+			(unreachable)
+		)
+	)
+
+	(func (export "call")
+		;; This stores the block timestamp in the scratch buffer
+		(call $ext_now)
+
+		;; assert $ext_scratch_size == 8
+		(call $assert
+			(i32.eq
+				(call $ext_scratch_size)
+				(i32.const 8)
+			)
+		)
+
+		;; copy contents of the scratch buffer into the contract's memory.
+		(call $ext_scratch_copy
+			(i32.const 8)		;; Pointer in memory to the place where to copy.
+			(i32.const 0)		;; Offset from the start of the scratch buffer.
+			(i32.const 8)		;; Count of bytes to copy.
+		)
+
+		;; assert that contents of the buffer is equal to the i64 value of 1111.
+		(call $assert
+			(i64.eq
+				(i64.load
+					(i32.const 8)
+				)
+				(i64.const 1111)
+			)
+		)
+	)
+	(func (export "deploy"))
+)
+"#;
+
+	#[test]
+	fn now() {
+		let mut mock_ext = MockExt::default();
+		let mut gas_meter = GasMeter::with_limit(50_000, 1);
+		execute(
+			CODE_TIMESTAMP_NOW,
+			&[],
+			&mut Vec::new(),
+			&mut mock_ext,
+			&mut gas_meter,
+		)
+		.unwrap();
+	}
+
+	const CODE_RANDOM_SEED: &str = r#"
+(module
+	(import "env" "ext_random_seed" (func $ext_random_seed))
+	(import "env" "ext_scratch_size" (func $ext_scratch_size (result i32)))
+	(import "env" "ext_scratch_copy" (func $ext_scratch_copy (param i32 i32 i32)))
+	(import "env" "memory" (memory 1 1))
+
+	(func $assert (param i32)
+		(block $ok
+			(br_if $ok
+				(get_local 0)
+			)
+			(unreachable)
+		)
+	)
+
+	(func (export "call")
+		;; This stores the block random seed in the scratch buffer
+		(call $ext_random_seed)
+
+		;; assert $ext_scratch_size == 32
+		(call $assert
+			(i32.eq
+				(call $ext_scratch_size)
+				(i32.const 32)
+			)
+		)
+
+		;; copy contents of the scratch buffer into the contract's memory.
+		(call $ext_scratch_copy
+			(i32.const 8)		;; Pointer in memory to the place where to copy.
+			(i32.const 0)		;; Offset from the start of the scratch buffer.
+			(i32.const 32)		;; Count of bytes to copy.
+		)
+
+		;; assert the contents of the buffer in 4 x i64 parts matches 1,2,3,4.
+		(call $assert (i64.eq (i64.load (i32.const 8))  (i64.const 1)))
+		(call $assert (i64.eq (i64.load (i32.const 16)) (i64.const 2)))
+		(call $assert (i64.eq (i64.load (i32.const 24)) (i64.const 3)))
+		(call $assert (i64.eq (i64.load (i32.const 32)) (i64.const 4)))
+	)
+	(func (export "deploy"))
+)
+"#;
+
+	#[test]
+	fn random_seed() {
+		let mut mock_ext = MockExt::default();
+		let seed: [u8; 32] = [
+			1,0,0,0,0,0,0,0,
+			2,0,0,0,0,0,0,0,
+			3,0,0,0,0,0,0,0,
+			4,0,0,0,0,0,0,0,
+		];
+		mock_ext.random_seed = H256::from_slice(&seed);
+		let mut gas_meter = GasMeter::with_limit(50_000, 1);
+		execute(
+			CODE_RANDOM_SEED,
+			&[],
+			&mut Vec::new(),
+			&mut mock_ext,
+			&mut gas_meter,
+		)
+		.unwrap();
+	}
+
 }

substrate/srml/contract/src/wasm/runtime.rs

@@ -482,6 +482,19 @@ define_env!(Env, <E: Ext>,
 		Ok(())
 	},
 
+	// Load the latest block RNG seed into the scratch buffer
+	ext_random_seed(ctx) => {
+		ctx.scratch_buf = ctx.ext.random_seed().encode();
+		Ok(())
+	},
+
+	// Load the latest block timestamp into the scratch buffer
+	ext_now(ctx) => {
+		let now: u64 = As::as_(ctx.ext.now().clone());
+		ctx.scratch_buf = now.encode();
+		Ok(())
+	},
+
 	// Decodes the given buffer as a `T::Call` and adds it to the list
 	// of to-be-dispatched calls.
 	//