Add initial no_std support

Add initial no_std support for embedded platforms

ci/check-compiles.sh

@@ -6,3 +6,4 @@ cargo check
 cargo doc
 cargo doc --document-private-items
 cd fuzz && cargo check --features=stdin_fuzz
+cd ../lightning && cargo check --default-features=false --features=core

lightning/Cargo.toml

@@ -21,14 +21,18 @@ max_level_error = []
 max_level_warn = []
 max_level_info = []
 max_level_debug = []
+std = []
+core = ["hashbrown"]
 # Allow signing of local transactions that may have been revoked or will be revoked, for functional testing (e.g. justice tx handling).
 # This is unsafe to use in production because it may result in the counterparty publishing taking our funds.
 unsafe_revoked_tx_signing = []
 unstable = []
+default = ["std"]
 
 [dependencies]
 bitcoin = "0.26"
 
+hashbrown = { version = "0.9", optional = true }
 hex = { version = "0.3", optional = true }
 regex = { version = "0.1.80", optional = true }
 

lightning/src/chain/chainmonitor.rs

@@ -37,9 +37,11 @@ use util::logger::Logger;
 use util::events;
 use util::events::Event;
 
-use std::collections::{HashMap, hash_map};
+use alloc::vec::Vec;
+use core::ops::Deref;
+use crate::{HashMap, hash_map};
 use std::sync::RwLock;
-use std::ops::Deref;
+
 
 /// An implementation of [`chain::Watch`] for monitoring channels.
 ///
@@ -324,6 +326,9 @@ mod tests {
 	use util::events::MessageSendEventsProvider;
 	use util::test_utils::{OnRegisterOutput, TxOutReference};
 
+    #[macro_use]
+    use alloc::vec;
+
 	/// Tests that in-block dependent transactions are processed by `block_connected` when not
 	/// included in `txdata` but returned by [`chain::Filter::register_output`]. For instance,
 	/// a (non-anchor) commitment transaction's HTLC output may be spent in the same block as the

lightning/src/chain/channelmonitor.rs

@@ -51,10 +51,11 @@ use util::ser::{Readable, ReadableArgs, MaybeReadable, Writer, Writeable, U48};
 use util::byte_utils;
 use util::events::Event;
 
-use std::collections::{HashMap, HashSet};
-use std::{cmp, mem};
+#[macro_use]
+use alloc::{boxed::Box, vec, vec::Vec};
+use crate::{HashMap, HashSet};
+use core::{cmp, mem, ops::Deref};
 use std::io::Error;
-use std::ops::Deref;
 use std::sync::Mutex;
 
 /// An update generated by the underlying Channel itself which contains some new information the
@@ -85,7 +86,7 @@ pub struct ChannelMonitorUpdate {
 /// then we allow the `ChannelManager` to send a `ChannelMonitorUpdate` with this update ID,
 /// with the update providing said payment preimage. No other update types are allowed after
 /// force-close.
-pub const CLOSED_CHANNEL_UPDATE_ID: u64 = std::u64::MAX;
+pub const CLOSED_CHANNEL_UPDATE_ID: u64 = ::core::u64::MAX;
 
 impl Writeable for ChannelMonitorUpdate {
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {
@@ -101,7 +102,7 @@ impl Readable for ChannelMonitorUpdate {
 	fn read<R: ::std::io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 		let update_id: u64 = Readable::read(r)?;
 		let len: u64 = Readable::read(r)?;
-		let mut updates = Vec::with_capacity(cmp::min(len as usize, MAX_ALLOC_SIZE / ::std::mem::size_of::<ChannelMonitorUpdateStep>()));
+		let mut updates = Vec::with_capacity(cmp::min(len as usize, MAX_ALLOC_SIZE / ::core::mem::size_of::<ChannelMonitorUpdateStep>()));
 		for _ in 0..len {
 			updates.push(Readable::read(r)?);
 		}
@@ -1932,7 +1933,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 
 		for &(ref htlc, _, _) in holder_tx.htlc_outputs.iter() {
 			if let Some(transaction_output_index) = htlc.transaction_output_index {
-				claim_requests.push(ClaimRequest { absolute_timelock: ::std::u32::MAX, aggregable: false, outpoint: BitcoinOutPoint { txid: holder_tx.txid, vout: transaction_output_index as u32 },
+				claim_requests.push(ClaimRequest { absolute_timelock: ::core::u32::MAX, aggregable: false, outpoint: BitcoinOutPoint { txid: holder_tx.txid, vout: transaction_output_index as u32 },
 					witness_data: InputMaterial::HolderHTLC {
 						preimage: if !htlc.offered {
 								if let Some(preimage) = self.payment_preimages.get(&htlc.payment_hash) {
@@ -2594,7 +2595,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 	fn is_paying_spendable_output<L: Deref>(&mut self, tx: &Transaction, height: u32, logger: &L) where L::Target: Logger {
 		let mut spendable_output = None;
 		for (i, outp) in tx.output.iter().enumerate() { // There is max one spendable output for any channel tx, including ones generated by us
-			if i > ::std::u16::MAX as usize {
+			if i > ::core::u16::MAX as usize {
 				// While it is possible that an output exists on chain which is greater than the
 				// 2^16th output in a given transaction, this is only possible if the output is not
 				// in a lightning transaction and was instead placed there by some third party who
@@ -3060,6 +3061,7 @@ mod tests {
 	use bitcoin::secp256k1::Secp256k1;
 	use std::sync::{Arc, Mutex};
 	use chain::keysinterface::InMemorySigner;
+    use alloc::vec::Vec;
 
 	#[test]
 	fn test_prune_preimages() {

lightning/src/chain/keysinterface.rs

@@ -37,8 +37,10 @@ use ln::chan_utils;
 use ln::chan_utils::{HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, HolderCommitmentTransaction, ChannelTransactionParameters, CommitmentTransaction};
 use ln::msgs::UnsignedChannelAnnouncement;
 
-use std::collections::HashSet;
-use std::sync::atomic::{AtomicUsize, Ordering};
+#[macro_use]
+use alloc::{vec, vec::Vec};
+use core::sync::atomic::{AtomicUsize, Ordering};
+use crate::HashSet;
 use std::io::Error;
 use ln::msgs::{DecodeError, MAX_VALUE_MSAT};
 
@@ -850,7 +852,7 @@ impl KeysManager {
 	/// onchain output detection for which a corresponding delayed_payment_key must be derived.
 	pub fn derive_channel_keys(&self, channel_value_satoshis: u64, params: &[u8; 32]) -> InMemorySigner {
 		let chan_id = byte_utils::slice_to_be64(&params[0..8]);
-		assert!(chan_id <= std::u32::MAX as u64); // Otherwise the params field wasn't created by us
+		assert!(chan_id <= core::u32::MAX as u64); // Otherwise the params field wasn't created by us
 		let mut unique_start = Sha256::engine();
 		unique_start.input(params);
 		unique_start.input(&self.seed);
@@ -1032,7 +1034,7 @@ impl KeysInterface for KeysManager {
 
 	fn get_channel_signer(&self, _inbound: bool, channel_value_satoshis: u64) -> Self::Signer {
 		let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
-		assert!(child_ix <= std::u32::MAX as usize);
+		assert!(child_ix <= core::u32::MAX as usize);
 		let mut id = [0; 32];
 		id[0..8].copy_from_slice(&byte_utils::be64_to_array(child_ix as u64));
 		id[8..16].copy_from_slice(&byte_utils::be64_to_array(self.starting_time_nanos as u64));

lightning/src/chain/mod.rs

@@ -9,6 +9,8 @@
 
 //! Structs and traits which allow other parts of rust-lightning to interact with the blockchain.
 
+use alloc::vec::Vec;
+
 use bitcoin::blockdata::block::{Block, BlockHeader};
 use bitcoin::blockdata::script::Script;
 use bitcoin::blockdata::transaction::{Transaction, TxOut};
@@ -246,7 +248,7 @@ pub struct WatchedOutput {
 	pub script_pubkey: Script,
 }
 
-impl<T: Listen> Listen for std::ops::Deref<Target = T> {
+impl<T: Listen> Listen for core::ops::Deref<Target = T> {
 	fn block_connected(&self, block: &Block, height: u32) {
 		(**self).block_connected(block, height);
 	}
@@ -256,7 +258,7 @@ impl<T: Listen> Listen for std::ops::Deref<Target = T> {
 	}
 }
 
-impl<T: std::ops::Deref, U: std::ops::Deref> Listen for (T, U)
+impl<T: core::ops::Deref, U: core::ops::Deref> Listen for (T, U)
 where
 	T::Target: Listen,
 	U::Target: Listen,

lightning/src/lib.rs

@@ -21,6 +21,7 @@
 #![cfg_attr(not(any(feature = "fuzztarget", feature = "_test_utils")), deny(missing_docs))]
 #![cfg_attr(not(any(test, feature = "fuzztarget", feature = "_test_utils")), forbid(unsafe_code))]
 #![deny(broken_intra_doc_links)]
+#![cfg_attr(feature = "core", no_std)]
 
 // In general, rust is absolutely horrid at supporting users doing things like,
 // for example, compiling Rust code for real environments. Disable useless lints
@@ -35,6 +36,15 @@ extern crate bitcoin;
 #[cfg(any(test, feature = "_test_utils"))] extern crate hex;
 #[cfg(any(test, feature = "fuzztarget", feature = "_test_utils"))] extern crate regex;
 
+extern crate alloc;
+#[cfg(feature = "std")] extern crate core;
+#[cfg(feature = "core")] extern crate hashbrown;
+
+#[cfg(feature = "core")]
+use hashbrown::{HashMap, HashSet, hash_map};
+#[cfg(feature = "std")]
+use std::collections::{HashMap, HashSet, hash_map};
+
 #[macro_use]
 pub mod util;
 pub mod chain;

lightning/src/ln/chan_utils.rs

@@ -31,12 +31,12 @@ use bitcoin::secp256k1::{Secp256k1, Signature, Message};
 use bitcoin::secp256k1::Error as SecpError;
 use bitcoin::secp256k1;
 
-use std::cmp;
+use alloc::vec::Vec;
+use core::{cmp, ops::Deref};
 use ln::chan_utils;
 use util::transaction_utils::sort_outputs;
 use ln::channel::INITIAL_COMMITMENT_NUMBER;
 use std::io::Read;
-use std::ops::Deref;
 use chain;
 
 // Maximum size of a serialized HTLCOutputInCommitment
@@ -1235,6 +1235,7 @@ fn script_for_p2wpkh(key: &PublicKey) -> Script {
 mod tests {
 	use super::CounterpartyCommitmentSecrets;
 	use hex;
+    use alloc::vec::Vec;
 
 	#[test]
 	fn test_per_commitment_storage() {

lightning/src/ln/chanmon_update_fail_tests.rs

@@ -37,6 +37,9 @@ use ln::functional_test_utils::*;
 
 use util::test_utils;
 
+#[macro_use]
+use alloc::{vec, vec::Vec};
+
 // If persister_fail is true, we have the persister return a PermanentFailure
 // instead of the higher-level ChainMonitor.
 fn do_test_simple_monitor_permanent_update_fail(persister_fail: bool) {

lightning/src/ln/channel.rs

@@ -39,9 +39,9 @@ use util::errors::APIError;
 use util::config::{UserConfig,ChannelConfig};
 use util::scid_utils::scid_from_parts;
 
-use std;
-use std::{cmp,mem,fmt};
-use std::ops::Deref;
+#[macro_use]
+use alloc::{format, boxed::Box, string::String, vec, vec::Vec};
+use core::{cmp, mem, fmt, ops::Deref};
 #[cfg(any(test, feature = "fuzztarget"))]
 use std::sync::Mutex;
 use bitcoin::hashes::hex::ToHex;
@@ -1217,7 +1217,7 @@ impl<Signer: Sign> Channel<Signer> {
 		// on-chain ChannelsMonitors during block rescan. Ideally we'd figure out a way to drop
 		// these, but for now we just have to treat them as normal.
 
-		let mut pending_idx = std::usize::MAX;
+		let mut pending_idx = core::usize::MAX;
 		for (idx, htlc) in self.pending_inbound_htlcs.iter().enumerate() {
 			if htlc.htlc_id == htlc_id_arg {
 				assert_eq!(htlc.payment_hash, payment_hash_calc);
@@ -1240,7 +1240,7 @@ impl<Signer: Sign> Channel<Signer> {
 				break;
 			}
 		}
-		if pending_idx == std::usize::MAX {
+		if pending_idx == core::usize::MAX {
 			return Err(ChannelError::Ignore("Unable to find a pending HTLC which matched the given HTLC ID".to_owned()));
 		}
 
@@ -1339,7 +1339,7 @@ impl<Signer: Sign> Channel<Signer> {
 		// on-chain ChannelsMonitors during block rescan. Ideally we'd figure out a way to drop
 		// these, but for now we just have to treat them as normal.
 
-		let mut pending_idx = std::usize::MAX;
+		let mut pending_idx = core::usize::MAX;
 		for (idx, htlc) in self.pending_inbound_htlcs.iter().enumerate() {
 			if htlc.htlc_id == htlc_id_arg {
 				match htlc.state {
@@ -1356,7 +1356,7 @@ impl<Signer: Sign> Channel<Signer> {
 				pending_idx = idx;
 			}
 		}
-		if pending_idx == std::usize::MAX {
+		if pending_idx == core::usize::MAX {
 			return Err(ChannelError::Ignore("Unable to find a pending HTLC which matched the given HTLC ID".to_owned()));
 		}
 
@@ -4394,8 +4394,8 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
 
 		let mut key_data = VecWriter(Vec::new());
 		self.holder_signer.write(&mut key_data)?;
-		assert!(key_data.0.len() < std::usize::MAX);
-		assert!(key_data.0.len() < std::u32::MAX as usize);
+		assert!(key_data.0.len() < core::usize::MAX);
+		assert!(key_data.0.len() < core::u32::MAX as usize);
 		(key_data.0.len() as u32).write(writer)?;
 		writer.write_all(&key_data.0[..])?;
 
@@ -4859,6 +4859,9 @@ mod tests {
 	use bitcoin::hash_types::{Txid, WPubkeyHash};
 	use std::sync::Arc;
 
+	#[macro_use]
+	use alloc::{vec, vec::Vec};
+
 	struct TestFeeEstimator {
 		fee_est: u32
 	}

lightning/src/ln/channelmanager.rs

@@ -61,15 +61,20 @@ use util::chacha20::{ChaCha20, ChaChaReader};
 use util::logger::Logger;
 use util::errors::APIError;
 
-use std::{cmp, mem};
-use std::collections::{HashMap, hash_map, HashSet};
+#[macro_use]
+use alloc::{format, vec, string::String, vec::Vec};
+use core::{
+    cmp,
+    mem,
+    ops::Deref,
+    sync::atomic::{AtomicUsize, Ordering},
+    time::Duration,
+};
+use crate::{HashMap, HashSet, hash_map};
 use std::io::{Cursor, Read};
 use std::sync::{Arc, Condvar, Mutex, MutexGuard, RwLock, RwLockReadGuard};
-use std::sync::atomic::{AtomicUsize, Ordering};
-use std::time::Duration;
 #[cfg(any(test, feature = "allow_wallclock_use"))]
 use std::time::Instant;
-use std::ops::Deref;
 use bitcoin::hashes::hex::ToHex;
 
 // We hold various information about HTLC relay in the HTLC objects in Channel itself:
@@ -1748,7 +1753,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 	// be absurd. We ensure this by checking that at least 500 (our stated public contract on when
 	// broadcast_node_announcement panics) of the maximum-length addresses would fit in a 64KB
 	// message...
-	const HALF_MESSAGE_IS_ADDRS: u32 = ::std::u16::MAX as u32 / (NetAddress::MAX_LEN as u32 + 1) / 2;
+	const HALF_MESSAGE_IS_ADDRS: u32 = core::u16::MAX as u32 / (NetAddress::MAX_LEN as u32 + 1) / 2;
 	#[deny(const_err)]
 	#[allow(dead_code)]
 	// ...by failing to compile if the number of addresses that would be half of a message is
@@ -4716,9 +4721,8 @@ impl<'a, Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
 mod tests {
 	use ln::channelmanager::PersistenceNotifier;
 	use std::sync::Arc;
-	use std::sync::atomic::{AtomicBool, Ordering};
+	use core::{sync::atomic::{AtomicBool, Ordering}, time::Duration};
 	use std::thread;
-	use std::time::Duration;
 
 	#[test]
 	fn test_wait_timeout() {
@@ -4783,6 +4787,8 @@ pub mod bench {
 	use bitcoin::hashes::sha256::Hash as Sha256;
 	use bitcoin::{Block, BlockHeader, Transaction, TxOut};
 
+    use alloc::vec::Vec;
+    use core::default::Default;
 	use std::sync::Mutex;
 
 	use test::Bencher;