Return Result from methods of ChainAdapter (#2722)

Most of the methods return nothing or bool which is used to decide if a
sender of a message should be banned or not. However underlying chain
implementation may fail so we need a way to reflect this fact in API.

Also it allows to reduce number of unwraps and makes the code more robust.

Cargo.lock

@@ -853,6 +853,7 @@ dependencies = [
  "bytes 0.4.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "chrono 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "enum_primitive 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "grin_chain 1.0.3",
  "grin_core 1.0.3",
  "grin_pool 1.0.3",
  "grin_store 1.0.3",

p2p/Cargo.toml

@@ -24,6 +24,7 @@ chrono = { version = "0.4.4", features = ["serde"] }
 
 grin_core = { path = "../core", version = "1.0.3" }
 grin_store = { path = "../store", version = "1.0.3" }
+grin_chain = { path = "../chain", version = "1.0.3" }
 grin_util = { path = "../util", version = "1.0.3" }
 
 [dev-dependencies]

p2p/src/lib.rs

@@ -29,6 +29,7 @@ use lmdb_zero as lmdb;
 
 #[macro_use]
 extern crate grin_core as core;
+use grin_chain as chain;
 use grin_util as util;
 
 #[macro_use]

p2p/src/peer.rs

@@ -17,6 +17,7 @@ use std::fs::File;
 use std::net::{Shutdown, TcpStream};
 use std::sync::Arc;
 
+use crate::chain;
 use crate::conn;
 use crate::core::core::hash::{Hash, Hashed};
 use crate::core::pow::Difficulty;
@@ -513,11 +514,11 @@ impl TrackingAdapter {
 }
 
 impl ChainAdapter for TrackingAdapter {
-	fn total_difficulty(&self) -> Difficulty {
+	fn total_difficulty(&self) -> Result<Difficulty, chain::Error> {
 		self.adapter.total_difficulty()
 	}
 
-	fn total_height(&self) -> u64 {
+	fn total_height(&self) -> Result<u64, chain::Error> {
 		self.adapter.total_height()
 	}
 
@@ -525,12 +526,16 @@ impl ChainAdapter for TrackingAdapter {
 		self.adapter.get_transaction(kernel_hash)
 	}
 
-	fn tx_kernel_received(&self, kernel_hash: Hash, addr: PeerAddr) {
+	fn tx_kernel_received(&self, kernel_hash: Hash, addr: PeerAddr) -> Result<bool, chain::Error> {
 		self.push_recv(kernel_hash);
 		self.adapter.tx_kernel_received(kernel_hash, addr)
 	}
 
-	fn transaction_received(&self, tx: core::Transaction, stem: bool) {
+	fn transaction_received(
+		&self,
+		tx: core::Transaction,
+		stem: bool,
+	) -> Result<bool, chain::Error> {
 		// Do not track the tx hash for stem txs.
 		// Otherwise we fail to handle the subsequent fluff or embargo expiration
 		// correctly.
@@ -541,27 +546,40 @@ impl ChainAdapter for TrackingAdapter {
 		self.adapter.transaction_received(tx, stem)
 	}
 
-	fn block_received(&self, b: core::Block, addr: PeerAddr, _was_requested: bool) -> bool {
+	fn block_received(
+		&self,
+		b: core::Block,
+		addr: PeerAddr,
+		_was_requested: bool,
+	) -> Result<bool, chain::Error> {
 		let bh = b.hash();
 		self.push_recv(bh);
 		self.adapter.block_received(b, addr, self.has_req(bh))
 	}
 
-	fn compact_block_received(&self, cb: core::CompactBlock, addr: PeerAddr) -> bool {
+	fn compact_block_received(
+		&self,
+		cb: core::CompactBlock,
+		addr: PeerAddr,
+	) -> Result<bool, chain::Error> {
 		self.push_recv(cb.hash());
 		self.adapter.compact_block_received(cb, addr)
 	}
 
-	fn header_received(&self, bh: core::BlockHeader, addr: PeerAddr) -> bool {
+	fn header_received(&self, bh: core::BlockHeader, addr: PeerAddr) -> Result<bool, chain::Error> {
 		self.push_recv(bh.hash());
 		self.adapter.header_received(bh, addr)
 	}
 
-	fn headers_received(&self, bh: &[core::BlockHeader], addr: PeerAddr) -> bool {
+	fn headers_received(
+		&self,
+		bh: &[core::BlockHeader],
+		addr: PeerAddr,
+	) -> Result<bool, chain::Error> {
 		self.adapter.headers_received(bh, addr)
 	}
 
-	fn locate_headers(&self, locator: &[Hash]) -> Vec<core::BlockHeader> {
+	fn locate_headers(&self, locator: &[Hash]) -> Result<Vec<core::BlockHeader>, chain::Error> {
 		self.adapter.locate_headers(locator)
 	}
 
@@ -577,7 +595,12 @@ impl ChainAdapter for TrackingAdapter {
 		self.adapter.txhashset_receive_ready()
 	}
 
-	fn txhashset_write(&self, h: Hash, txhashset_data: File, peer_addr: PeerAddr) -> bool {
+	fn txhashset_write(
+		&self,
+		h: Hash,
+		txhashset_data: File,
+		peer_addr: PeerAddr,
+	) -> Result<bool, chain::Error> {
 		self.adapter.txhashset_write(h, txhashset_data, peer_addr)
 	}
 

p2p/src/peers.rs

@@ -19,6 +19,7 @@ use std::sync::Arc;
 
 use rand::{thread_rng, Rng};
 
+use crate::chain;
 use crate::core::core;
 use crate::core::core::hash::{Hash, Hashed};
 use crate::core::global;
@@ -171,13 +172,13 @@ impl Peers {
 
 	// Return vec of connected peers that currently advertise more work
 	// (total_difficulty) than we do.
-	pub fn more_work_peers(&self) -> Vec<Arc<Peer>> {
+	pub fn more_work_peers(&self) -> Result<Vec<Arc<Peer>>, chain::Error> {
 		let peers = self.connected_peers();
 		if peers.len() == 0 {
-			return vec![];
+			return Ok(vec![]);
 		}
 
-		let total_difficulty = self.total_difficulty();
+		let total_difficulty = self.total_difficulty()?;
 
 		let mut max_peers = peers
 			.into_iter()
@@ -185,28 +186,34 @@ impl Peers {
 			.collect::<Vec<_>>();
 
 		thread_rng().shuffle(&mut max_peers);
-		max_peers
+		Ok(max_peers)
 	}
 
 	// Return number of connected peers that currently advertise more/same work
 	// (total_difficulty) than/as we do.
-	pub fn more_or_same_work_peers(&self) -> usize {
+	pub fn more_or_same_work_peers(&self) -> Result<usize, chain::Error> {
 		let peers = self.connected_peers();
 		if peers.len() == 0 {
-			return 0;
+			return Ok(0);
 		}
 
-		let total_difficulty = self.total_difficulty();
+		let total_difficulty = self.total_difficulty()?;
 
-		peers
+		Ok(peers
 			.iter()
 			.filter(|x| x.info.total_difficulty() >= total_difficulty)
-			.count()
+			.count())
 	}
 
 	/// Returns single random peer with more work than us.
 	pub fn more_work_peer(&self) -> Option<Arc<Peer>> {
-		self.more_work_peers().pop()
+		match self.more_work_peers() {
+			Ok(mut peers) => peers.pop(),
+			Err(e) => {
+				error!("failed to get more work peers: {:?}", e);
+				None
+			}
+		}
 	}
 
 	/// Return vec of connected peers that currently have the most worked
@@ -452,10 +459,15 @@ impl Peers {
 				rm.push(peer.info.addr.clone());
 			} else {
 				let (stuck, diff) = peer.is_stuck();
-				if stuck && diff < self.adapter.total_difficulty() {
-					debug!("clean_peers {:?}, stuck peer", peer.info.addr);
-					let _ = self.update_state(peer.info.addr, State::Defunct);
-					rm.push(peer.info.addr.clone());
+				match self.adapter.total_difficulty() {
+					Ok(total_difficulty) => {
+						if stuck && diff < total_difficulty {
+							debug!("clean_peers {:?}, stuck peer", peer.info.addr);
+							let _ = self.update_state(peer.info.addr, State::Defunct);
+							rm.push(peer.info.addr.clone());
+						}
+					}
+					Err(e) => error!("failed to get total difficulty: {:?}", e),
 				}
 			}
 		}
@@ -529,11 +541,11 @@ impl Peers {
 }
 
 impl ChainAdapter for Peers {
-	fn total_difficulty(&self) -> Difficulty {
+	fn total_difficulty(&self) -> Result<Difficulty, chain::Error> {
 		self.adapter.total_difficulty()
 	}
 
-	fn total_height(&self) -> u64 {
+	fn total_height(&self) -> Result<u64, chain::Error> {
 		self.adapter.total_height()
 	}
 
@@ -541,17 +553,26 @@ impl ChainAdapter for Peers {
 		self.adapter.get_transaction(kernel_hash)
 	}
 
-	fn tx_kernel_received(&self, kernel_hash: Hash, addr: PeerAddr) {
+	fn tx_kernel_received(&self, kernel_hash: Hash, addr: PeerAddr) -> Result<bool, chain::Error> {
 		self.adapter.tx_kernel_received(kernel_hash, addr)
 	}
 
-	fn transaction_received(&self, tx: core::Transaction, stem: bool) {
+	fn transaction_received(
+		&self,
+		tx: core::Transaction,
+		stem: bool,
+	) -> Result<bool, chain::Error> {
 		self.adapter.transaction_received(tx, stem)
 	}
 
-	fn block_received(&self, b: core::Block, peer_addr: PeerAddr, was_requested: bool) -> bool {
+	fn block_received(
+		&self,
+		b: core::Block,
+		peer_addr: PeerAddr,
+		was_requested: bool,
+	) -> Result<bool, chain::Error> {
 		let hash = b.hash();
-		if !self.adapter.block_received(b, peer_addr, was_requested) {
+		if !self.adapter.block_received(b, peer_addr, was_requested)? {
 			// if the peer sent us a block that's intrinsically bad
 			// they are either mistaken or malevolent, both of which require a ban
 			debug!(
@@ -559,15 +580,19 @@ impl ChainAdapter for Peers {
 				hash, peer_addr
 			);
 			self.ban_peer(peer_addr, ReasonForBan::BadBlock);
-			false
+			Ok(false)
 		} else {
-			true
+			Ok(true)
 		}
 	}
 
-	fn compact_block_received(&self, cb: core::CompactBlock, peer_addr: PeerAddr) -> bool {
+	fn compact_block_received(
+		&self,
+		cb: core::CompactBlock,
+		peer_addr: PeerAddr,
+	) -> Result<bool, chain::Error> {
 		let hash = cb.hash();
-		if !self.adapter.compact_block_received(cb, peer_addr) {
+		if !self.adapter.compact_block_received(cb, peer_addr)? {
 			// if the peer sent us a block that's intrinsically bad
 			// they are either mistaken or malevolent, both of which require a ban
 			debug!(
@@ -575,35 +600,43 @@ impl ChainAdapter for Peers {
 				hash, peer_addr
 			);
 			self.ban_peer(peer_addr, ReasonForBan::BadCompactBlock);
-			false
+			Ok(false)
 		} else {
-			true
+			Ok(true)
 		}
 	}
 
-	fn header_received(&self, bh: core::BlockHeader, peer_addr: PeerAddr) -> bool {
-		if !self.adapter.header_received(bh, peer_addr) {
+	fn header_received(
+		&self,
+		bh: core::BlockHeader,
+		peer_addr: PeerAddr,
+	) -> Result<bool, chain::Error> {
+		if !self.adapter.header_received(bh, peer_addr)? {
 			// if the peer sent us a block header that's intrinsically bad
 			// they are either mistaken or malevolent, both of which require a ban
 			self.ban_peer(peer_addr, ReasonForBan::BadBlockHeader);
-			false
+			Ok(false)
 		} else {
-			true
+			Ok(true)
 		}
 	}
 
-	fn headers_received(&self, headers: &[core::BlockHeader], peer_addr: PeerAddr) -> bool {
-		if !self.adapter.headers_received(headers, peer_addr) {
+	fn headers_received(
+		&self,
+		headers: &[core::BlockHeader],
+		peer_addr: PeerAddr,
+	) -> Result<bool, chain::Error> {
+		if !self.adapter.headers_received(headers, peer_addr)? {
 			// if the peer sent us a block header that's intrinsically bad
 			// they are either mistaken or malevolent, both of which require a ban
 			self.ban_peer(peer_addr, ReasonForBan::BadBlockHeader);
-			false
+			Ok(false)
 		} else {
-			true
+			Ok(true)
 		}
 	}
 
-	fn locate_headers(&self, hs: &[Hash]) -> Vec<core::BlockHeader> {
+	fn locate_headers(&self, hs: &[Hash]) -> Result<Vec<core::BlockHeader>, chain::Error> {
 		self.adapter.locate_headers(hs)
 	}
 
@@ -619,16 +652,21 @@ impl ChainAdapter for Peers {
 		self.adapter.txhashset_receive_ready()
 	}
 
-	fn txhashset_write(&self, h: Hash, txhashset_data: File, peer_addr: PeerAddr) -> bool {
-		if !self.adapter.txhashset_write(h, txhashset_data, peer_addr) {
+	fn txhashset_write(
+		&self,
+		h: Hash,
+		txhashset_data: File,
+		peer_addr: PeerAddr,
+	) -> Result<bool, chain::Error> {
+		if !self.adapter.txhashset_write(h, txhashset_data, peer_addr)? {
 			debug!(
 				"Received a bad txhashset data from {}, the peer will be banned",
 				&peer_addr
 			);
 			self.ban_peer(peer_addr, ReasonForBan::BadTxHashSet);
-			false
+			Ok(false)
 		} else {
-			true
+			Ok(true)
 		}
 	}
 

p2p/src/protocol.rs

@@ -68,8 +68,8 @@ impl MessageHandler for Protocol {
 				Ok(Some(Response::new(
 					Type::Pong,
 					Pong {
-						total_difficulty: adapter.total_difficulty(),
-						height: adapter.total_height(),
+						total_difficulty: adapter.total_difficulty()?,
+						height: adapter.total_height()?,
 					},
 					writer,
 				)?))
@@ -93,7 +93,7 @@ impl MessageHandler for Protocol {
 					"handle_payload: received tx kernel: {}, msg_len: {}",
 					h, msg.header.msg_len
 				);
-				adapter.tx_kernel_received(h, self.addr);
+				adapter.tx_kernel_received(h, self.addr)?;
 				Ok(None)
 			}
 
@@ -117,7 +117,7 @@ impl MessageHandler for Protocol {
 					msg.header.msg_len
 				);
 				let tx: core::Transaction = msg.body()?;
-				adapter.transaction_received(tx, false);
+				adapter.transaction_received(tx, false)?;
 				Ok(None)
 			}
 
@@ -127,7 +127,7 @@ impl MessageHandler for Protocol {
 					msg.header.msg_len
 				);
 				let tx: core::Transaction = msg.body()?;
-				adapter.transaction_received(tx, true);
+				adapter.transaction_received(tx, true)?;
 				Ok(None)
 			}
 
@@ -155,7 +155,7 @@ impl MessageHandler for Protocol {
 
 				// we can't know at this level whether we requested the block or not,
 				// the boolean should be properly set in higher level adapter
-				adapter.block_received(b, self.addr, false);
+				adapter.block_received(b, self.addr, false)?;
 				Ok(None)
 			}
 
@@ -176,14 +176,14 @@ impl MessageHandler for Protocol {
 				);
 				let b: core::CompactBlock = msg.body()?;
 
-				adapter.compact_block_received(b, self.addr);
+				adapter.compact_block_received(b, self.addr)?;
 				Ok(None)
 			}
 
 			Type::GetHeaders => {
 				// load headers from the locator
 				let loc: Locator = msg.body()?;
-				let headers = adapter.locate_headers(&loc.hashes);
+				let headers = adapter.locate_headers(&loc.hashes)?;
 
 				// serialize and send all the headers over
 				Ok(Some(Response::new(
@@ -197,7 +197,7 @@ impl MessageHandler for Protocol {
 			// we can go request it from some of our peers
 			Type::Header => {
 				let header: core::BlockHeader = msg.body()?;
-				adapter.header_received(header, self.addr);
+				adapter.header_received(header, self.addr)?;
 				Ok(None)
 			}
 
@@ -217,7 +217,7 @@ impl MessageHandler for Protocol {
 						headers.push(header);
 						total_bytes_read += bytes_read;
 					}
-					adapter.headers_received(&headers, self.addr);
+					adapter.headers_received(&headers, self.addr)?;
 				}
 
 				// Now check we read the correct total number of bytes off the stream.
@@ -335,7 +335,7 @@ impl MessageHandler for Protocol {
 				let tmp_zip = File::open(tmp)?;
 				let res = self
 					.adapter
-					.txhashset_write(sm_arch.hash, tmp_zip, self.addr);
+					.txhashset_write(sm_arch.hash, tmp_zip, self.addr)?;
 
 				debug!(
 					"handle_payload: txhashset archive for {} at {}, DONE. Data Ok: {}",

p2p/src/serv.rs

@@ -12,19 +12,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use std::fs::File;
-use std::net::{Shutdown, SocketAddr, TcpListener, TcpStream};
-use std::sync::Arc;
-use std::time::Duration;
-use std::{io, thread};
-
-use crate::lmdb;
-
+use crate::chain;
 use crate::core::core;
 use crate::core::core::hash::Hash;
 use crate::core::global;
 use crate::core::pow::Difficulty;
 use crate::handshake::Handshake;
+use crate::lmdb;
 use crate::peer::Peer;
 use crate::peers::Peers;
 use crate::store::PeerStore;
@@ -33,6 +27,11 @@ use crate::types::{
 };
 use crate::util::{Mutex, StopState};
 use chrono::prelude::{DateTime, Utc};
+use std::fs::File;
+use std::net::{Shutdown, SocketAddr, TcpListener, TcpStream};
+use std::sync::Arc;
+use std::time::Duration;
+use std::{io, thread};
 
 /// P2P server implementation, handling bootstrapping to find and connect to
 /// peers, receiving connections from other peers and keep track of all of them.
@@ -139,7 +138,7 @@ impl Server {
 		match TcpStream::connect_timeout(&addr.0, Duration::from_secs(10)) {
 			Ok(mut stream) => {
 				let addr = SocketAddr::new(self.config.host, self.config.port);
-				let total_diff = self.peers.total_difficulty();
+				let total_diff = self.peers.total_difficulty()?;
 
 				let mut peer = Peer::connect(
 					&mut stream,
@@ -168,7 +167,7 @@ impl Server {
 	}
 
 	fn handle_new_peer(&self, mut stream: TcpStream) -> Result<(), Error> {
-		let total_diff = self.peers.total_difficulty();
+		let total_diff = self.peers.total_difficulty()?;
 
 		// accept the peer and add it to the server map
 		let mut peer = Peer::accept(
@@ -231,31 +230,48 @@ impl Server {
 pub struct DummyAdapter {}
 
 impl ChainAdapter for DummyAdapter {
-	fn total_difficulty(&self) -> Difficulty {
-		Difficulty::min()
+	fn total_difficulty(&self) -> Result<Difficulty, chain::Error> {
+		Ok(Difficulty::min())
 	}
-	fn total_height(&self) -> u64 {
-		0
+	fn total_height(&self) -> Result<u64, chain::Error> {
+		Ok(0)
 	}
 	fn get_transaction(&self, _h: Hash) -> Option<core::Transaction> {
 		None
 	}
-	fn tx_kernel_received(&self, _h: Hash, _addr: PeerAddr) {}
-	fn transaction_received(&self, _: core::Transaction, _stem: bool) {}
-	fn compact_block_received(&self, _cb: core::CompactBlock, _addr: PeerAddr) -> bool {
-		true
+
+	fn tx_kernel_received(&self, _h: Hash, _addr: PeerAddr) -> Result<bool, chain::Error> {
+		Ok(true)
 	}
-	fn header_received(&self, _bh: core::BlockHeader, _addr: PeerAddr) -> bool {
-		true
+	fn transaction_received(
+		&self,
+		_: core::Transaction,
+		_stem: bool,
+	) -> Result<bool, chain::Error> {
+		Ok(true)
 	}
-	fn block_received(&self, _: core::Block, _: PeerAddr, _: bool) -> bool {
-		true
+	fn compact_block_received(
+		&self,
+		_cb: core::CompactBlock,
+		_addr: PeerAddr,
+	) -> Result<bool, chain::Error> {
+		Ok(true)
 	}
-	fn headers_received(&self, _: &[core::BlockHeader], _: PeerAddr) -> bool {
-		true
+	fn header_received(
+		&self,
+		_bh: core::BlockHeader,
+		_addr: PeerAddr,
+	) -> Result<bool, chain::Error> {
+		Ok(true)
 	}
-	fn locate_headers(&self, _: &[Hash]) -> Vec<core::BlockHeader> {
-		vec![]
+	fn block_received(&self, _: core::Block, _: PeerAddr, _: bool) -> Result<bool, chain::Error> {
+		Ok(true)
+	}
+	fn headers_received(&self, _: &[core::BlockHeader], _: PeerAddr) -> Result<bool, chain::Error> {
+		Ok(true)
+	}
+	fn locate_headers(&self, _: &[Hash]) -> Result<Vec<core::BlockHeader>, chain::Error> {
+		Ok(vec![])
 	}
 	fn get_block(&self, _: Hash) -> Option<core::Block> {
 		None
@@ -268,8 +284,13 @@ impl ChainAdapter for DummyAdapter {
 		false
 	}
 
-	fn txhashset_write(&self, _h: Hash, _txhashset_data: File, _peer_addr: PeerAddr) -> bool {
-		false
+	fn txhashset_write(
+		&self,
+		_h: Hash,
+		_txhashset_data: File,
+		_peer_addr: PeerAddr,
+	) -> Result<bool, chain::Error> {
+		Ok(false)
 	}
 
 	fn txhashset_download_update(

p2p/src/store.rs

@@ -168,7 +168,8 @@ impl PeerStore {
 	/// Used for /v1/peers/all api endpoint
 	pub fn all_peers(&self) -> Result<Vec<PeerData>, Error> {
 		let key = to_key(PEER_PREFIX, &mut "".to_string().into_bytes());
-		Ok(self.db
+		Ok(self
+			.db
 			.iter::<PeerData>(&key)?
 			.map(|(_, v)| v)
 			.collect::<Vec<_>>())

p2p/src/types.rs

@@ -23,6 +23,7 @@ use std::sync::Arc;
 
 use chrono::prelude::*;
 
+use crate::chain;
 use crate::core::core;
 use crate::core::core::hash::Hash;
 use crate::core::global;
@@ -63,6 +64,7 @@ pub enum Error {
 	ConnectionClose,
 	Timeout,
 	Store(grin_store::Error),
+	Chain(chain::Error),
 	PeerWithSelf,
 	NoDandelionRelay,
 	ProtocolMismatch {
@@ -88,6 +90,11 @@ impl From<grin_store::Error> for Error {
 		Error::Store(e)
 	}
 }
+impl From<chain::Error> for Error {
+	fn from(e: chain::Error) -> Error {
+		Error::Chain(e)
+	}
+}
 impl From<io::Error> for Error {
 	fn from(e: io::Error) -> Error {
 		Error::Connection(e)
@@ -465,37 +472,51 @@ pub struct TxHashSetRead {
 /// other things.
 pub trait ChainAdapter: Sync + Send {
 	/// Current total difficulty on our chain
-	fn total_difficulty(&self) -> Difficulty;
+	fn total_difficulty(&self) -> Result<Difficulty, chain::Error>;
 
 	/// Current total height
-	fn total_height(&self) -> u64;
+	fn total_height(&self) -> Result<u64, chain::Error>;
 
 	/// A valid transaction has been received from one of our peers
-	fn transaction_received(&self, tx: core::Transaction, stem: bool);
+	fn transaction_received(&self, tx: core::Transaction, stem: bool)
+		-> Result<bool, chain::Error>;
 
 	fn get_transaction(&self, kernel_hash: Hash) -> Option<core::Transaction>;
 
-	fn tx_kernel_received(&self, kernel_hash: Hash, addr: PeerAddr);
+	fn tx_kernel_received(&self, kernel_hash: Hash, addr: PeerAddr) -> Result<bool, chain::Error>;
 
 	/// A block has been received from one of our peers. Returns true if the
 	/// block could be handled properly and is not deemed defective by the
 	/// chain. Returning false means the block will never be valid and
 	/// may result in the peer being banned.
-	fn block_received(&self, b: core::Block, addr: PeerAddr, was_requested: bool) -> bool;
+	fn block_received(
+		&self,
+		b: core::Block,
+		addr: PeerAddr,
+		was_requested: bool,
+	) -> Result<bool, chain::Error>;
 
-	fn compact_block_received(&self, cb: core::CompactBlock, addr: PeerAddr) -> bool;
+	fn compact_block_received(
+		&self,
+		cb: core::CompactBlock,
+		addr: PeerAddr,
+	) -> Result<bool, chain::Error>;
 
-	fn header_received(&self, bh: core::BlockHeader, addr: PeerAddr) -> bool;
+	fn header_received(&self, bh: core::BlockHeader, addr: PeerAddr) -> Result<bool, chain::Error>;
 
 	/// A set of block header has been received, typically in response to a
 	/// block
 	/// header request.
-	fn headers_received(&self, bh: &[core::BlockHeader], addr: PeerAddr) -> bool;
+	fn headers_received(
+		&self,
+		bh: &[core::BlockHeader],
+		addr: PeerAddr,
+	) -> Result<bool, chain::Error>;
 
 	/// Finds a list of block headers based on the provided locator. Tries to
 	/// identify the common chain and gets the headers that follow it
 	/// immediately.
-	fn locate_headers(&self, locator: &[Hash]) -> Vec<core::BlockHeader>;
+	fn locate_headers(&self, locator: &[Hash]) -> Result<Vec<core::BlockHeader>, chain::Error>;
 
 	/// Gets a full block by its hash.
 	fn get_block(&self, h: Hash) -> Option<core::Block>;
@@ -523,7 +544,12 @@ pub trait ChainAdapter: Sync + Send {
 	/// If we're willing to accept that new state, the data stream will be
 	/// read as a zip file, unzipped and the resulting state files should be
 	/// rewound to the provided indexes.
-	fn txhashset_write(&self, h: Hash, txhashset_data: File, peer_addr: PeerAddr) -> bool;
+	fn txhashset_write(
+		&self,
+		h: Hash,
+		txhashset_data: File,
+		peer_addr: PeerAddr,
+	) -> Result<bool, chain::Error>;
 }
 
 /// Additional methods required by the protocol that don't need to be

servers/src/common/adapters.rs

@@ -50,22 +50,22 @@ pub struct NetToChainAdapter {
 }
 
 impl p2p::ChainAdapter for NetToChainAdapter {
-	fn total_difficulty(&self) -> Difficulty {
-		self.chain().head().unwrap().total_difficulty
+	fn total_difficulty(&self) -> Result<Difficulty, chain::Error> {
+		Ok(self.chain().head()?.total_difficulty)
 	}
 
-	fn total_height(&self) -> u64 {
-		self.chain().head().unwrap().height
+	fn total_height(&self) -> Result<u64, chain::Error> {
+		Ok(self.chain().head()?.height)
 	}
 
 	fn get_transaction(&self, kernel_hash: Hash) -> Option<core::Transaction> {
 		self.tx_pool.read().retrieve_tx_by_kernel_hash(kernel_hash)
 	}
 
-	fn tx_kernel_received(&self, kernel_hash: Hash, addr: PeerAddr) {
+	fn tx_kernel_received(&self, kernel_hash: Hash, addr: PeerAddr) -> Result<bool, chain::Error> {
 		// nothing much we can do with a new transaction while syncing
 		if self.sync_state.is_syncing() {
-			return;
+			return Ok(true);
 		}
 
 		let tx = self.tx_pool.read().retrieve_tx_by_kernel_hash(kernel_hash);
@@ -73,12 +73,17 @@ impl p2p::ChainAdapter for NetToChainAdapter {
 		if tx.is_none() {
 			self.request_transaction(kernel_hash, addr);
 		}
+		Ok(true)
 	}
 
-	fn transaction_received(&self, tx: core::Transaction, stem: bool) {
+	fn transaction_received(
+		&self,
+		tx: core::Transaction,
+		stem: bool,
+	) -> Result<bool, chain::Error> {
 		// nothing much we can do with a new transaction while syncing
 		if self.sync_state.is_syncing() {
-			return;
+			return Ok(true);
 		}
 
 		let source = pool::TxSource {
@@ -87,7 +92,7 @@ impl p2p::ChainAdapter for NetToChainAdapter {
 		};
 
 		let tx_hash = tx.hash();
-		let header = self.chain().head_header().unwrap();
+		let header = self.chain().head_header()?;
 
 		debug!(
 			"Received tx {}, [in/out/kern: {}/{}/{}] going to process.",
@@ -97,17 +102,22 @@ impl p2p::ChainAdapter for NetToChainAdapter {
 			tx.kernels().len(),
 		);
 
-		let res = {
-			let mut tx_pool = self.tx_pool.write();
-			tx_pool.add_to_pool(source, tx, stem, &header)
-		};
-
-		if let Err(e) = res {
-			debug!("Transaction {} rejected: {:?}", tx_hash, e);
+		let mut tx_pool = self.tx_pool.write();
+		match tx_pool.add_to_pool(source, tx, stem, &header) {
+			Ok(_) => Ok(true),
+			Err(e) => {
+				debug!("Transaction {} rejected: {:?}", tx_hash, e);
+				Ok(false)
+			}
 		}
 	}
 
-	fn block_received(&self, b: core::Block, addr: PeerAddr, was_requested: bool) -> bool {
+	fn block_received(
+		&self,
+		b: core::Block,
+		addr: PeerAddr,
+		was_requested: bool,
+	) -> Result<bool, chain::Error> {
 		debug!(
 			"Received block {} at {} from {} [in/out/kern: {}/{}/{}] going to process.",
 			b.hash(),
@@ -120,7 +130,11 @@ impl p2p::ChainAdapter for NetToChainAdapter {
 		self.process_block(b, addr, was_requested)
 	}
 
-	fn compact_block_received(&self, cb: core::CompactBlock, addr: PeerAddr) -> bool {
+	fn compact_block_received(
+		&self,
+		cb: core::CompactBlock,
+		addr: PeerAddr,
+	) -> Result<bool, chain::Error> {
 		let bhash = cb.hash();
 		debug!(
 			"Received compact_block {} at {} from {} [out/kern/kern_ids: {}/{}/{}] going to process.",
@@ -139,7 +153,7 @@ impl p2p::ChainAdapter for NetToChainAdapter {
 				Ok(block) => self.process_block(block, addr, false),
 				Err(e) => {
 					debug!("Invalid hydrated block {}: {:?}", cb_hash, e);
-					return false;
+					return Ok(false);
 				}
 			}
 		} else {
@@ -149,7 +163,7 @@ impl p2p::ChainAdapter for NetToChainAdapter {
 				.process_block_header(&cb.header, self.chain_opts(false))
 			{
 				debug!("Invalid compact block header {}: {:?}", cb_hash, e.kind());
-				return !e.is_bad_data();
+				return Ok(!e.is_bad_data());
 			}
 
 			let (txs, missing_short_ids) = {
@@ -173,7 +187,7 @@ impl p2p::ChainAdapter for NetToChainAdapter {
 				Ok(block) => block,
 				Err(e) => {
 					debug!("Invalid hydrated block {}: {:?}", cb.hash(), e);
-					return false;
+					return Ok(false);
 				}
 			};
 
@@ -188,20 +202,20 @@ impl p2p::ChainAdapter for NetToChainAdapter {
 					if self.sync_state.status() == SyncStatus::NoSync {
 						debug!("adapter: block invalid after hydration, requesting full block");
 						self.request_block(&cb.header, addr);
-						true
+						Ok(true)
 					} else {
 						debug!("block invalid after hydration, ignoring it, cause still syncing");
-						true
+						Ok(true)
 					}
 				}
 			} else {
 				debug!("failed to retrieve previous block header (still syncing?)");
-				true
+				Ok(true)
 			}
 		}
 	}
 
-	fn header_received(&self, bh: core::BlockHeader, addr: PeerAddr) -> bool {
+	fn header_received(&self, bh: core::BlockHeader, addr: PeerAddr) -> Result<bool, chain::Error> {
 		let bhash = bh.hash();
 		debug!(
 			"Received block header {} at {} from {}, going to process.",
@@ -214,14 +228,14 @@ impl p2p::ChainAdapter for NetToChainAdapter {
 			.chain()
 			.process_block_header(&bh, self.chain_opts(false));
 
-		if let &Err(ref e) = &res {
+		if let Err(e) = res {
 			debug!("Block header {} refused by chain: {:?}", bhash, e.kind());
 			if e.is_bad_data() {
-				return false;
+				return Ok(false);
 			} else {
 				// we got an error when trying to process the block header
 				// but nothing serious enough to need to ban the peer upstream
-				return true;
+				return Err(e);
 			}
 		}
 
@@ -230,37 +244,43 @@ impl p2p::ChainAdapter for NetToChainAdapter {
 		self.request_compact_block(&bh, addr);
 
 		// done receiving the header
-		true
+		Ok(true)
 	}
 
-	fn headers_received(&self, bhs: &[core::BlockHeader], addr: PeerAddr) -> bool {
+	fn headers_received(
+		&self,
+		bhs: &[core::BlockHeader],
+		addr: PeerAddr,
+	) -> Result<bool, chain::Error> {
 		info!("Received {} block headers from {}", bhs.len(), addr,);
 
 		if bhs.len() == 0 {
-			return false;
+			return Ok(false);
 		}
 
 		// try to add headers to our header chain
-		let res = self.chain().sync_block_headers(bhs, self.chain_opts(true));
-		if let &Err(ref e) = &res {
-			debug!("Block headers refused by chain: {:?}", e);
-
-			if e.is_bad_data() {
-				return false;
+		match self.chain().sync_block_headers(bhs, self.chain_opts(true)) {
+			Ok(_) => Ok(true),
+			Err(e) => {
+				debug!("Block headers refused by chain: {:?}", e);
+				if e.is_bad_data() {
+					return Ok(false);
+				} else {
+					Err(e)
+				}
 			}
 		}
-		true
 	}
 
-	fn locate_headers(&self, locator: &[Hash]) -> Vec<core::BlockHeader> {
+	fn locate_headers(&self, locator: &[Hash]) -> Result<Vec<core::BlockHeader>, chain::Error> {
 		debug!("locator: {:?}", locator);
 
 		let header = match self.find_common_header(locator) {
 			Some(header) => header,
-			None => return vec![],
+			None => return Ok(vec![]),
 		};
 
-		let max_height = self.chain().header_head().unwrap().height;
+		let max_height = self.chain().header_head()?.height;
 
 		let txhashset = self.chain().txhashset();
 		let txhashset = txhashset.read();
@@ -283,7 +303,7 @@ impl p2p::ChainAdapter for NetToChainAdapter {
 
 		debug!("returning headers: {}", headers.len());
 
-		headers
+		Ok(headers)
 	}
 
 	/// Gets a full block by its hash.
@@ -348,11 +368,16 @@ impl p2p::ChainAdapter for NetToChainAdapter {
 	/// If we're willing to accept that new state, the data stream will be
 	/// read as a zip file, unzipped and the resulting state files should be
 	/// rewound to the provided indexes.
-	fn txhashset_write(&self, h: Hash, txhashset_data: File, _peer_addr: PeerAddr) -> bool {
+	fn txhashset_write(
+		&self,
+		h: Hash,
+		txhashset_data: File,
+		_peer_addr: PeerAddr,
+	) -> Result<bool, chain::Error> {
 		// check status again after download, in case 2 txhashsets made it somehow
 		if let SyncStatus::TxHashsetDownload { .. } = self.sync_state.status() {
 		} else {
-			return true;
+			return Ok(true);
 		}
 
 		if let Err(e) = self
@@ -361,12 +386,13 @@ impl p2p::ChainAdapter for NetToChainAdapter {
 		{
 			self.chain().clean_txhashset_sandbox();
 			error!("Failed to save txhashset archive: {}", e);
+
 			let is_good_data = !e.is_bad_data();
 			self.sync_state.set_sync_error(types::Error::Chain(e));
-			is_good_data
+			Ok(is_good_data)
 		} else {
 			info!("Received valid txhashset data for {}.", h);
-			true
+			Ok(true)
 		}
 	}
 }
@@ -428,15 +454,20 @@ impl NetToChainAdapter {
 
 	// pushing the new block through the chain pipeline
 	// remembering to reset the head if we have a bad block
-	fn process_block(&self, b: core::Block, addr: PeerAddr, was_requested: bool) -> bool {
+	fn process_block(
+		&self,
+		b: core::Block,
+		addr: PeerAddr,
+		was_requested: bool,
+	) -> Result<bool, chain::Error> {
 		// We cannot process blocks earlier than the horizon so check for this here.
 		{
-			let head = self.chain().head().unwrap();
+			let head = self.chain().head()?;
 			let horizon = head
 				.height
 				.saturating_sub(global::cut_through_horizon() as u64);
 			if b.header.height < horizon {
-				return true;
+				return Ok(true);
 			}
 		}
 
@@ -450,11 +481,11 @@ impl NetToChainAdapter {
 			Ok(_) => {
 				self.validate_chain(bhash);
 				self.check_compact();
-				true
+				Ok(true)
 			}
 			Err(ref e) if e.is_bad_data() => {
 				self.validate_chain(bhash);
-				false
+				Ok(false)
 			}
 			Err(e) => {
 				match e.kind() {
@@ -468,7 +499,7 @@ impl NetToChainAdapter {
 								self.request_block_by_hash(previous.hash(), addr)
 							}
 						}
-						true
+						Ok(true)
 					}
 					_ => {
 						debug!(
@@ -476,7 +507,7 @@ impl NetToChainAdapter {
 							bhash,
 							e.kind()
 						);
-						true
+						Ok(true)
 					}
 				}
 			}

servers/src/grin/seed.rs

@@ -129,8 +129,12 @@ pub fn connect_and_monitor(
 				if Utc::now() - prev_ping > Duration::seconds(10) {
 					let total_diff = peers.total_difficulty();
 					let total_height = peers.total_height();
-					peers.check_all(total_diff, total_height);
-					prev_ping = Utc::now();
+					if total_diff.is_ok() && total_height.is_ok() {
+						peers.check_all(total_diff.unwrap(), total_height.unwrap());
+						prev_ping = Utc::now();
+					} else {
+						error!("failed to get peers difficulty and/or height");
+					}
 				}
 
 				thread::sleep(time::Duration::from_secs(1));

servers/src/grin/sync/body_sync.rs

@@ -100,7 +100,7 @@ impl BodySync {
 
 		hashes.reverse();
 
-		let peers = self.peers.more_work_peers();
+		let peers = self.peers.more_work_peers()?;
 
 		// if we have 5 peers to sync from then ask for 50 blocks total (peer_count *
 		// 10) max will be 80 if all 8 peers are advertising more work

servers/src/grin/sync/syncer.rs

@@ -77,7 +77,7 @@ impl SyncRunner {
 		let mut n = 0;
 		const MIN_PEERS: usize = 3;
 		loop {
-			let wp = self.peers.more_or_same_work_peers();
+			let wp = self.peers.more_or_same_work_peers()?;
 			// exit loop when:
 			// * we have more than MIN_PEERS more_or_same_work peers
 			// * we are synced already, e.g. grin was quickly restarted