fix(extract timestamp_checked_add as lib) (#10383)

* fix(extract `timestamp_checked_add` as lib)

* fix(whisper types): remove unused `EmptyTopics`

* fix(time-lib): feature-flag to use time-lib or std

This commit adds conditional compilation checks that falls back to `our time-lib` when
`time_checked_add` is not available in the standard library

Note, `time_checked_add` covers both `checked_add` and `checked_sub`

* fix(grumble): use cfg_attr to define rustc feature

Cargo.toml

@@ -138,7 +138,8 @@ members = [
 	"util/triehash-ethereum",
 	"util/keccak-hasher",
 	"util/patricia-trie-ethereum",
-	"util/fastmap"
+	"util/fastmap",
+	"util/time-utils"
 ]
 
 [patch.crates-io]

ethcore/Cargo.toml

@@ -63,6 +63,7 @@ serde = "1.0"
 serde_derive = "1.0"
 stats = { path = "../util/stats" }
 tempdir = {version="0.3", optional = true}
+time-utils = { path = "../util/time-utils" }
 trace-time = "0.1"
 triehash-ethereum = { version = "0.2",  path = "../util/triehash-ethereum" }
 unexpected = { path = "../util/unexpected" }

ethcore/src/engines/authority_round/mod.rs

@@ -47,6 +47,9 @@ use types::header::{Header, ExtendedHeader};
 use types::ancestry_action::AncestryAction;
 use unexpected::{Mismatch, OutOfBounds};
 
+#[cfg(not(time_checked_add))]
+use time_utils::CheckedSystemTime;
+
 mod finality;
 
 /// `AuthorityRound` params.
@@ -574,8 +577,15 @@ fn verify_timestamp(step: &Step, header_step: u64) -> Result<(), BlockError> {
 			// NOTE This error might be returned only in early stage of verification (Stage 1).
 			// Returning it further won't recover the sync process.
 			trace!(target: "engine", "verify_timestamp: block too early");
-			let oob = oob.map(|n| SystemTime::now() + Duration::from_secs(n));
-			Err(BlockError::TemporarilyInvalid(oob).into())
+
+			let now = SystemTime::now();
+			let found = now.checked_add(Duration::from_secs(oob.found)).ok_or(BlockError::TimestampOverflow)?;
+			let max = oob.max.and_then(|m| now.checked_add(Duration::from_secs(m)));
+			let min = oob.min.and_then(|m| now.checked_add(Duration::from_secs(m)));
+
+			let new_oob = OutOfBounds { min, max, found };
+
+			Err(BlockError::TemporarilyInvalid(new_oob).into())
 		},
 		Ok(_) => Ok(()),
 	}
@@ -611,6 +621,7 @@ fn combine_proofs(signal_number: BlockNumber, set_proof: &[u8], finality_proof:
 	stream.out()
 }
 
+
 fn destructure_proofs(combined: &[u8]) -> Result<(BlockNumber, &[u8], &[u8]), Error> {
 	let rlp = Rlp::new(combined);
 	Ok((
@@ -626,7 +637,7 @@ trait AsMillis {
 
 impl AsMillis for Duration {
 	fn as_millis(&self) -> u64 {
-		self.as_secs()*1_000 + (self.subsec_nanos()/1_000_000) as u64
+		self.as_secs() * 1_000 + (self.subsec_nanos() / 1_000_000) as u64
 	}
 }
 

ethcore/src/lib.rs

@@ -15,6 +15,7 @@
 // along with Parity Ethereum.  If not, see <http://www.gnu.org/licenses/>.
 
 #![warn(missing_docs, unused_extern_crates)]
+#![cfg_attr(feature = "time_checked_add", feature(time_checked_add))]
 
 //! Ethcore library
 //!
@@ -148,6 +149,9 @@ extern crate fetch;
 #[cfg(all(test, feature = "price-info"))]
 extern crate parity_runtime;
 
+#[cfg(not(time_checked_add))]
+extern crate time_utils;
+
 pub mod block;
 pub mod builtin;
 pub mod client;

ethcore/src/verification/verification.rs

@@ -40,24 +40,8 @@ use types::{BlockNumber, header::Header};
 use types::transaction::SignedTransaction;
 use verification::queue::kind::blocks::Unverified;
 
-
-/// Returns `Ok<SystemTime>` when the result less or equal to `i32::max_value` to prevent `SystemTime` to panic because
-/// it is platform specific, may be i32 or i64.
-///
-/// `Err<BlockError::TimestampOver` otherwise.
-///
-// FIXME: @niklasad1 - remove this when and use `SystemTime::checked_add`
-// when https://github.com/rust-lang/rust/issues/55940 is stabilized.
-fn timestamp_checked_add(sys: SystemTime, d2: Duration) -> Result<SystemTime, BlockError> {
-	let d1 = sys.duration_since(UNIX_EPOCH).map_err(|_| BlockError::TimestampOverflow)?;
-	let total_time = d1.checked_add(d2).ok_or(BlockError::TimestampOverflow)?;
-
-	if total_time.as_secs() <= i32::max_value() as u64 {
-		Ok(sys + d2)
-	} else {
-		Err(BlockError::TimestampOverflow)
-	}
-}
+#[cfg(not(time_checked_add))]
+use time_utils::CheckedSystemTime;
 
 /// Preprocessed block data gathered in `verify_block_unordered` call
 pub struct PreverifiedBlock {
@@ -323,9 +307,11 @@ pub fn verify_header_params(header: &Header, engine: &EthEngine, is_full: bool,
 
 	if is_full {
 		const ACCEPTABLE_DRIFT: Duration = Duration::from_secs(15);
+		// this will resist overflow until `year 2037`
 		let max_time = SystemTime::now() + ACCEPTABLE_DRIFT;
 		let invalid_threshold = max_time + ACCEPTABLE_DRIFT * 9;
-		let timestamp = timestamp_checked_add(UNIX_EPOCH, Duration::from_secs(header.timestamp()))?;
+		let timestamp = UNIX_EPOCH.checked_add(Duration::from_secs(header.timestamp()))
+			.ok_or(BlockError::TimestampOverflow)?;
 
 		if timestamp > invalid_threshold {
 			return Err(From::from(BlockError::InvalidTimestamp(OutOfBounds { max: Some(max_time), min: None, found: timestamp })))
@@ -347,8 +333,11 @@ fn verify_parent(header: &Header, parent: &Header, engine: &EthEngine) -> Result
 	let gas_limit_divisor = engine.params().gas_limit_bound_divisor;
 
 	if !engine.is_timestamp_valid(header.timestamp(), parent.timestamp()) {
-		let min = timestamp_checked_add(SystemTime::now(), Duration::from_secs(parent.timestamp().saturating_add(1)))?;
-		let found = timestamp_checked_add(SystemTime::now(), Duration::from_secs(header.timestamp()))?;
+		let now = SystemTime::now();
+		let min = now.checked_add(Duration::from_secs(parent.timestamp().saturating_add(1)))
+			.ok_or(BlockError::TimestampOverflow)?;
+		let found = now.checked_add(Duration::from_secs(header.timestamp()))
+			.ok_or(BlockError::TimestampOverflow)?;
 		return Err(From::from(BlockError::InvalidTimestamp(OutOfBounds { max: None, min: Some(min), found })))
 	}
 	if header.number() != parent.number() + 1 {
@@ -835,11 +824,4 @@ mod tests {
 		check_fail(unordered_test(&create_test_block_with_data(&header, &bad_transactions, &[]), &engine), TooManyTransactions(keypair.address()));
 		unordered_test(&create_test_block_with_data(&header, &good_transactions, &[]), &engine).unwrap();
 	}
-
-	#[test]
-	fn checked_add_systime_dur() {
-		assert!(timestamp_checked_add(UNIX_EPOCH, Duration::new(i32::max_value() as u64 + 1, 0)).is_err());
-		assert!(timestamp_checked_add(UNIX_EPOCH, Duration::new(i32::max_value() as u64, 0)).is_ok());
-		assert!(timestamp_checked_add(UNIX_EPOCH, Duration::new(i32::max_value() as u64 - 1, 1_000_000_000)).is_ok());
-	}
 }

util/time-utils/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "time-utils"
+version = "0.1.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+description = "Time utilities for checked arithmetic"
+license = "GPL3"
+edition = "2018"
+
+[dependencies]

util/time-utils/src/lib.rs

@@ -0,0 +1,50 @@
+use std::time::{Duration, SystemTime, UNIX_EPOCH};
+
+/// Temporary trait for `checked operations` on SystemTime until these are available in standard library
+pub trait CheckedSystemTime {
+	/// Returns `Some<SystemTime>` when the result less or equal to `i32::max_value` to prevent `SystemTime` to panic because
+	/// it is platform specific, possible representations are i32, i64, u64 and Duration. `None` otherwise
+	fn checked_add(self, _d: Duration) -> Option<SystemTime>;
+	/// Returns `Some<SystemTime>` when the result is successful and `None` when it is not
+	fn checked_sub(self, _d: Duration) -> Option<SystemTime>;
+}
+
+impl CheckedSystemTime for SystemTime {
+	fn checked_add(self, dur: Duration) -> Option<SystemTime> {
+		let this_dur = self.duration_since(UNIX_EPOCH).ok()?;
+		let total_time = this_dur.checked_add(dur)?;
+
+		if total_time.as_secs() <= i32::max_value() as u64 {
+			Some(self + dur)
+		} else {
+			None
+		}
+	}
+
+	fn checked_sub(self, dur: Duration) -> Option<SystemTime> {
+		let this_dur = self.duration_since(UNIX_EPOCH).ok()?;
+		let total_time = this_dur.checked_sub(dur)?;
+
+		if total_time.as_secs() <= i32::max_value() as u64 {
+			Some(self - dur)
+		} else {
+			None
+		}
+	}
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn it_works() {
+		use super::CheckedSystemTime;
+		use std::time::{Duration, SystemTime, UNIX_EPOCH};
+
+		assert!(CheckedSystemTime::checked_add(UNIX_EPOCH, Duration::new(i32::max_value() as u64 + 1, 0)).is_none());
+		assert!(CheckedSystemTime::checked_add(UNIX_EPOCH, Duration::new(i32::max_value() as u64, 0)).is_some());
+		assert!(CheckedSystemTime::checked_add(UNIX_EPOCH, Duration::new(i32::max_value() as u64 - 1, 1_000_000_000)).is_some());
+
+		assert!(CheckedSystemTime::checked_sub(UNIX_EPOCH, Duration::from_secs(120)).is_none());
+		assert!(CheckedSystemTime::checked_sub(SystemTime::now(), Duration::from_secs(1000)).is_some());
+	}
+}

whisper/Cargo.toml

@@ -24,6 +24,7 @@ serde_json = "1.0"
 slab = "0.3"
 smallvec = "0.6"
 tiny-keccak = "1.4"
+time-utils = { path = "../util/time-utils" }
 
 jsonrpc-core = "10.0.1"
 jsonrpc-derive = "10.0.2"

whisper/src/lib.rs

@@ -17,6 +17,8 @@
 //! Whisper P2P messaging system as a DevP2P subprotocol, with RPC and Rust
 //! interface.
 
+#![cfg_attr(feature = "time_checked_add", feature(time_checked_add))]
+
 extern crate byteorder;
 extern crate parity_crypto as crypto;
 extern crate ethcore_network as network;
@@ -46,6 +48,9 @@ extern crate log;
 #[macro_use]
 extern crate serde_derive;
 
+#[cfg(not(time_checked_add))]
+extern crate time_utils;
+
 #[cfg(test)]
 extern crate serde_json;
 

whisper/src/message.rs

@@ -24,6 +24,9 @@ use rlp::{self, DecoderError, RlpStream, Rlp};
 use smallvec::SmallVec;
 use tiny_keccak::{keccak256, Keccak};
 
+#[cfg(not(time_checked_add))]
+use time_utils::CheckedSystemTime;
+
 /// Work-factor proved. Takes 3 parameters: size of message, time to live,
 /// and hash.
 ///
@@ -117,6 +120,7 @@ pub enum Error {
 	EmptyTopics,
 	LivesTooLong,
 	IssuedInFuture,
+	TimestampOverflow,
 	ZeroTTL,
 }
 
@@ -133,6 +137,7 @@ impl fmt::Display for Error {
 			Error::LivesTooLong => write!(f, "Message claims to be issued before the unix epoch."),
 			Error::IssuedInFuture => write!(f, "Message issued in future."),
 			Error::ZeroTTL => write!(f, "Message live for zero time."),
+			Error::TimestampOverflow => write!(f, "Timestamp overflow"),
 			Error::EmptyTopics => write!(f, "Message has no topics."),
 		}
 	}
@@ -226,10 +231,6 @@ impl rlp::Decodable for Envelope {
 	}
 }
 
-/// Error indicating no topics.
-#[derive(Debug, Copy, Clone)]
-pub struct EmptyTopics;
-
 /// Message creation parameters.
 /// Pass this to `Message::create` to make a message.
 pub struct CreateParams {
@@ -255,11 +256,11 @@ pub struct Message {
 impl Message {
 	/// Create a message from creation parameters.
 	/// Panics if TTL is 0.
-	pub fn create(params: CreateParams) -> Result<Self, EmptyTopics> {
+	pub fn create(params: CreateParams) -> Result<Self, Error> {
 		use byteorder::{BigEndian, ByteOrder};
 		use rand::{Rng, SeedableRng, XorShiftRng};
 
-		if params.topics.is_empty() { return Err(EmptyTopics) }
+		if params.topics.is_empty() { return Err(Error::EmptyTopics) }
 
 		let mut rng = {
 			let mut thread_rng = ::rand::thread_rng();
@@ -270,7 +271,8 @@ impl Message {
 		assert!(params.ttl > 0);
 
 		let expiry = {
-			let after_mining = SystemTime::now() + Duration::from_millis(params.work);
+			let after_mining = SystemTime::now().checked_sub(Duration::from_millis(params.work))
+				.ok_or(Error::TimestampOverflow)?;
 			let since_epoch = after_mining.duration_since(time::UNIX_EPOCH)
 				.expect("time after now is after unix epoch; qed");
 
@@ -357,7 +359,10 @@ impl Message {
 			(envelope.expiry - envelope.ttl).saturating_sub(LEEWAY_SECONDS)
 		);
 
-		if time::UNIX_EPOCH + issue_time_adjusted > now {
+		let issue_time_adjusted = time::UNIX_EPOCH.checked_add(issue_time_adjusted)
+			.ok_or(Error::TimestampOverflow)?;
+
+		if issue_time_adjusted > now {
 			return Err(Error::IssuedInFuture);
 		}
 
@@ -400,8 +405,8 @@ impl Message {
 	}
 
 	/// Get the expiry time.
-	pub fn expiry(&self) -> SystemTime {
-		time::UNIX_EPOCH + Duration::from_secs(self.envelope.expiry)
+	pub fn expiry(&self) -> Option<SystemTime> {
+		time::UNIX_EPOCH.checked_add(Duration::from_secs(self.envelope.expiry))
 	}
 
 	/// Get the topics.

whisper/src/net/mod.rs

@@ -223,7 +223,10 @@ impl Messages {
 			}
 		}
 
-		let expiry = message.expiry();
+		let expiry = match message.expiry() {
+			Some(time) => time,
+			_ => return false,
+		};
 
 		self.cumulative_size += message.encoded_size();
 
@@ -232,8 +235,8 @@ impl Messages {
 
 		let sorted_entry = SortedEntry {
 			slab_id: id,
-			work_proved: work_proved,
-			expiry: expiry,
+			work_proved,
+			expiry,
 		};
 
 		match self.sorted.binary_search(&sorted_entry) {