Interchain message-passing (#117)

* compute ingress and routing in polkadot runtime

* extract parent candidates from block when beginning consensus

* fetch incoming messages when validating

* fix consensus tests

* parachain wasm execution uses messages

* update parachain tests to check if messages are executed

* abstract out network service to make room for network tests

* skeleton for incoming data fetch

* collate ingress from consensus-gossip

* keep track of validated candidates in the shared-table

* add some shared_table tests for new behavior

* broadcast egress messages on gossip

* test compute_ingress

* move network tests to module folder

* dummy network for consensus-network tests

* make consensus network generic over executor

* test egress broadcast and ingress fetch

* fix test compilation

* address some grumbles

* address grumbles and fix parachain shuffle

* remove broadcast parameter from consensus network trait

polkadot/parachain/src/lib.rs

@@ -72,7 +72,7 @@ pub mod wasm_executor;
 pub mod wasm_api;
 
 /// Validation parameters for evaluating the parachain validity function.
-// TODO: consolidated ingress and balance downloads
+// TODO: balance downloads
 #[derive(PartialEq, Eq, Decode)]
 #[cfg_attr(feature = "std", derive(Debug, Encode))]
 pub struct ValidationParams {
@@ -80,6 +80,8 @@ pub struct ValidationParams {
 	pub block_data: Vec<u8>,
 	/// Previous head-data.
 	pub parent_head: Vec<u8>,
+	/// Incoming messages.
+	pub ingress: Vec<IncomingMessage>,
 }
 
 /// The result of parachain validation.
@@ -91,8 +93,17 @@ pub struct ValidationResult {
 	pub head_data: Vec<u8>,
 }
 
+/// An incoming message.
+#[derive(PartialEq, Eq, Decode)]
+#[cfg_attr(feature = "std", derive(Debug, Encode))]
+pub struct IncomingMessage {
+	/// The source parachain.
+	pub source: u32,
+	/// The data of the message.
+	pub data: Vec<u8>,
+}
+
 /// A reference to a message.
-#[cfg(feature = "std")]
 pub struct MessageRef<'a> {
 	/// The target parachain.
 	pub target: u32,

polkadot/parachain/src/wasm_api.rs

@@ -17,7 +17,7 @@
 //! Utilities for writing parachain WASM.
 
 use codec::{Encode, Decode};
-use super::{ValidationParams, ValidationResult, Message};
+use super::{ValidationParams, ValidationResult, MessageRef};
 
 mod ll {
 	extern "C" {
@@ -55,7 +55,7 @@ pub fn write_result(result: ValidationResult) -> usize {
 }
 
 /// Post a message to another parachain.
-pub fn post_message(message: &Message) {
+pub fn post_message(message: MessageRef) {
 	let data_ptr = message.data.as_ptr();
 	let data_len = message.data.len();
 

polkadot/parachain/tests/adder.rs

@@ -22,7 +22,7 @@ extern crate parity_codec as codec;
 extern crate polkadot_parachain as parachain;
 extern crate tiny_keccak;
 
-use parachain::{MessageRef, ValidationParams};
+use parachain::{MessageRef, IncomingMessage, ValidationParams};
 use parachain::wasm_executor::{Externalities, ExternalitiesError};
 use codec::{Decode, Encode};
 
@@ -46,6 +46,12 @@ struct BlockData {
 	add: u64,
 }
 
+#[derive(Encode, Decode)]
+struct AddMessage {
+	/// amount to add.
+	amount: u64,
+}
+
 struct DummyExt;
 impl Externalities for DummyExt {
 	fn post_message(&mut self, _message: MessageRef) -> Result<(), ExternalitiesError> {
@@ -81,6 +87,7 @@ fn execute_good_on_parent() {
 		ValidationParams {
 			parent_head: parent_head.encode(),
 			block_data: block_data.encode(),
+			ingress: Vec::new(),
 		},
 		&mut DummyExt,
 	).unwrap();
@@ -115,6 +122,7 @@ fn execute_good_chain_on_parent() {
 			ValidationParams {
 				parent_head: parent_head.encode(),
 				block_data: block_data.encode(),
+				ingress: Vec::new(),
 			},
 			&mut DummyExt,
 		).unwrap();
@@ -149,7 +157,45 @@ fn execute_bad_on_parent() {
 		ValidationParams {
 			parent_head: parent_head.encode(),
 			block_data: block_data.encode(),
+			ingress: Vec::new(),
 		},
 		&mut DummyExt,
 	).unwrap_err();
 }
+
+#[test]
+fn processes_messages() {
+	let parent_head = HeadData {
+		number: 0,
+		parent_hash: [0; 32],
+		post_state: hash_state(0),
+	};
+
+	let block_data = BlockData {
+		state: 0,
+		add: 512,
+	};
+
+	let bad_message_data = vec![1];
+	assert!(AddMessage::decode(&mut &bad_message_data[..]).is_none());
+
+	let ret = parachain::wasm_executor::validate_candidate(
+		TEST_CODE,
+		ValidationParams {
+			parent_head: parent_head.encode(),
+			block_data: block_data.encode(),
+			ingress: vec![
+				IncomingMessage { source: 1, data: (AddMessage { amount: 256 }).encode() },
+				IncomingMessage { source: 2, data: bad_message_data },
+				IncomingMessage { source: 3, data: (AddMessage { amount: 256 }).encode() },
+			],
+		},
+		&mut DummyExt,
+	).unwrap();
+
+	let new_head = HeadData::decode(&mut &ret.head_data[..]).unwrap();
+
+	assert_eq!(new_head.number, 1);
+	assert_eq!(new_head.parent_hash, hash_head(&parent_head));
+	assert_eq!(new_head.post_state, hash_state(1024));
+}