From 4bb4ed95516e8f8e31af774120fb434a6bf07855 Mon Sep 17 00:00:00 2001
From: Gav Wood <gavin@ethcore.io>
Date: Sun, 13 Nov 2016 15:52:33 +0100
Subject: [PATCH] Initial checking.

---
 Cargo.lock                   |  1 +
 ethcore/Cargo.toml           |  1 +
 ethcore/src/client/client.rs | 62 +++++++++++++++++++++++++++++++++++-
 ethcore/src/lib.rs           |  1 +
 util/src/misc.rs             |  5 +++
 5 files changed, 69 insertions(+), 1 deletion(-)

diff --git a/Cargo.lock b/Cargo.lock
index c3fa096b3..b53b28426 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -282,6 +282,7 @@ dependencies = [
  "clippy 0.0.96 (registry+https://github.com/rust-lang/crates.io-index)",
  "crossbeam 0.2.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "env_logger 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ethabi 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "ethash 1.4.0",
  "ethcore-bloom-journal 0.1.0",
  "ethcore-devtools 1.4.0",
diff --git a/ethcore/Cargo.toml b/ethcore/Cargo.toml
index 667b40ace..439263794 100644
--- a/ethcore/Cargo.toml
+++ b/ethcore/Cargo.toml
@@ -41,6 +41,7 @@ ethcore-ipc-nano = { path = "../ipc/nano" }
 rlp = { path = "../util/rlp" }
 lru-cache = "0.1.0"
 ethcore-bloom-journal = { path = "../util/bloom" }
+ethabi = "0.2.2"
 
 [dependencies.hyper]
 git = "https://github.com/ethcore/hyper"
diff --git a/ethcore/src/client/client.rs b/ethcore/src/client/client.rs
index ec59e01cf..400d53ed1 100644
--- a/ethcore/src/client/client.rs
+++ b/ethcore/src/client/client.rs
@@ -27,6 +27,7 @@ use util::{journaldb, TrieFactory, Trie};
 use util::trie::TrieSpec;
 use util::{U256, H256, Address, H2048, Uint, FixedHash};
 use util::kvdb::*;
+use util::misc::code_hash;
 
 // other
 use io::*;
@@ -42,7 +43,7 @@ use env_info::LastHashes;
 use verification;
 use verification::{PreverifiedBlock, Verifier};
 use block::*;
-use transaction::{LocalizedTransaction, SignedTransaction, Action};
+use transaction::{LocalizedTransaction, SignedTransaction, Transaction, Action};
 use blockchain::extras::TransactionAddress;
 use types::filter::Filter;
 use types::mode::Mode as IpcMode;
@@ -68,6 +69,7 @@ use factory::Factories;
 use rlp::{decode, View, UntrustedRlp};
 use state_db::StateDB;
 use rand::OsRng;
+use ethabi::{Interface, Contract, Token};
 
 // re-export
 pub use types::blockchain_info::BlockChainInfo;
@@ -634,10 +636,18 @@ impl Client {
 	/// Tick the client.
 	// TODO: manage by real events.
 	pub fn tick(&self) {
+		self.check_garbage();
+		self.check_snooze();
+		self.check_updates();
+	}
+
+	fn check_garbage(&self) {
 		self.chain.read().collect_garbage();
 		self.block_queue.collect_garbage();
 		self.tracedb.read().collect_garbage();
+	}
 
+	fn check_snooze(&self) {
 		let mode = self.mode.lock().clone();
 		match mode {
 			Mode::Dark(timeout) => {
@@ -671,6 +681,56 @@ impl Client {
 		}
 	}
 
+	fn call_contract(&self, address: Address, data: Bytes) -> Result<Bytes, String> {
+		let from = Address::default();
+		let transaction = Transaction {
+			nonce: self.latest_nonce(&from),
+			action: Action::Call(address),
+			gas: U256::from(50_000_000),
+			gas_price: U256::default(),
+			value: U256::default(),
+			data: data,
+		}.fake_sign(from);
+
+		self.call(&transaction, BlockID::Latest, Default::default())
+			.map_err(|e| format!("{:?}", e))
+			.map(|executed| {
+				executed.output
+			})
+	}
+
+	fn check_updates(&self) {
+		let operations_json = Interface::load(include_bytes!("../../res/Operations.json")).expect("Operations.json is valid ABI");
+		let operations = Contract::new(operations_json);
+
+		fn as_string<T: fmt::Debug>(e: T) -> String {
+			format!("{:?}", e)
+		}
+
+		let res = || {
+			let is_latest = try!(operations.function("isLatest".into()).map_err(as_string));
+			let params = try!(is_latest.encode_call(
+				vec![Token::String("par".into()), Token::Address(code_hash().0)]
+			).map_err(as_string));
+			let output = try!(self.call_contract("0x4c1783B4FfB1A99eFC4cda632aA990F5138b26f1".into(), params));
+			let result = try!(is_latest.decode_output(output).map_err(as_string));
+
+			match result.get(0) {
+				Some(&Token::Bool(answer)) => Ok(answer),
+				e => Err(format!("Invalid result: {:?}", e)),
+			}
+		};
+
+		match res() {
+			Ok(res) => {
+				info!("isLatest returned {}", res);
+			},
+			Err(e) => {
+				warn!(target: "dapps", "Error while calling Operations.isLatest: {:?}", e);
+			}
+		}
+	}
+
 	/// Look up the block number for the given block ID.
 	pub fn block_number(&self, id: BlockID) -> Option<BlockNumber> {
 		match id {
diff --git a/ethcore/src/lib.rs b/ethcore/src/lib.rs
index bf3e59171..59e45f381 100644
--- a/ethcore/src/lib.rs
+++ b/ethcore/src/lib.rs
@@ -117,6 +117,7 @@ extern crate lru_cache;
 
 #[cfg(feature = "jit" )]
 extern crate evmjit;
+extern crate ethabi;
 
 pub extern crate ethstore;
 
diff --git a/util/src/misc.rs b/util/src/misc.rs
index b0452e85e..d9eab1af0 100644
--- a/util/src/misc.rs
+++ b/util/src/misc.rs
@@ -32,6 +32,11 @@ pub enum Filth {
 	Dirty,
 }
 
+/// Get the (SHA1?) 160-bit hash of this build's code base.
+pub fn code_hash() -> H160 {
+	sha().into()
+}
+
 /// Get the standard version string for this software.
 pub fn version() -> String {
 	let sha3 = short_sha();