X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fln%2Fpeer_channel_encryptor.rs;h=8569fa60ffef46268fd020578dc22cb1e455649d;hb=eb23c1e43b0372e53c0b19b1eeafebeef50d2089;hp=8b276990cb689846680fa7de24070a4a433325de;hpb=48edd01d02a68258c046bff0e2bd05d25efd28ce;p=rust-lightning

diff --git a/lightning/src/ln/peer_channel_encryptor.rs b/lightning/src/ln/peer_channel_encryptor.rs
index 8b276990..8569fa60 100644
--- a/lightning/src/ln/peer_channel_encryptor.rs
+++ b/lightning/src/ln/peer_channel_encryptor.rs
@@ -427,16 +427,20 @@ impl PeerChannelEncryptor {
 		Ok(self.their_node_id.unwrap().clone())
 	}
 
-	/// Encrypts the given pre-serialized message, returning the encrypted version.
-	/// panics if msg.len() > 65535 or Noise handshake has not finished.
-	pub fn encrypt_buffer(&mut self, msg: &[u8]) -> Vec<u8> {
-		if msg.len() > LN_MAX_MSG_LEN {
+	/// Builds sendable bytes for a message.
+	///
+	/// `msgbuf` must begin with 16 + 2 dummy/0 bytes, which will be filled with the encrypted
+	/// message length and its MAC. It should then be followed by the message bytes themselves
+	/// (including the two byte message type).
+	///
+	/// For effeciency, the [`Vec::capacity`] should be at least 16 bytes larger than the
+	/// [`Vec::len`], to avoid reallocating for the message MAC, which will be appended to the vec.
+	fn encrypt_message_with_header_0s(&mut self, msgbuf: &mut Vec<u8>) {
+		let msg_len = msgbuf.len() - 16 - 2;
+		if msg_len > LN_MAX_MSG_LEN {
 			panic!("Attempted to encrypt message longer than 65535 bytes!");
 		}
 
-		let mut res = Vec::with_capacity(msg.len() + 16*2 + 2);
-		res.resize(msg.len() + 16*2 + 2, 0);
-
 		match self.noise_state {
 			NoiseState::Finished { ref mut sk, ref mut sn, ref mut sck, rk: _, rn: _, rck: _ } => {
 				if *sn >= 1000 {
@@ -446,16 +450,21 @@ impl PeerChannelEncryptor {
 					*sn = 0;
 				}
 
-				Self::encrypt_with_ad(&mut res[0..16+2], *sn, sk, &[0; 0], &(msg.len() as u16).to_be_bytes());
+				Self::encrypt_with_ad(&mut msgbuf[0..16+2], *sn, sk, &[0; 0], &(msg_len as u16).to_be_bytes());
 				*sn += 1;
 
-				Self::encrypt_with_ad(&mut res[16+2..], *sn, sk, &[0; 0], msg);
+				Self::encrypt_in_place_with_ad(msgbuf, 16+2, *sn, sk, &[0; 0]);
 				*sn += 1;
 			},
 			_ => panic!("Tried to encrypt a message prior to noise handshake completion"),
 		}
+	}
 
-		res
+	/// Encrypts the given pre-serialized message, returning the encrypted version.
+	/// panics if msg.len() > 65535 or Noise handshake has not finished.
+	pub fn encrypt_buffer(&mut self, mut msg: MessageBuf) -> Vec<u8> {
+		self.encrypt_message_with_header_0s(&mut msg.0);
+		msg.0
 	}
 
 	/// Encrypts the given message, returning the encrypted version.
@@ -468,29 +477,7 @@ impl PeerChannelEncryptor {
 		res.0.resize(16 + 2, 0);
 		wire::write(message, &mut res).expect("In-memory messages must never fail to serialize");
 
-		let msg_len = res.0.len() - 16 - 2;
-		if msg_len > LN_MAX_MSG_LEN {
-			panic!("Attempted to encrypt message longer than 65535 bytes!");
-		}
-
-		match self.noise_state {
-			NoiseState::Finished { ref mut sk, ref mut sn, ref mut sck, rk: _, rn: _, rck: _ } => {
-				if *sn >= 1000 {
-					let (new_sck, new_sk) = hkdf_extract_expand_twice(sck, sk);
-					*sck = new_sck;
-					*sk = new_sk;
-					*sn = 0;
-				}
-
-				Self::encrypt_with_ad(&mut res.0[0..16+2], *sn, sk, &[0; 0], &(msg_len as u16).to_be_bytes());
-				*sn += 1;
-
-				Self::encrypt_in_place_with_ad(&mut res.0, 16+2, *sn, sk, &[0; 0]);
-				*sn += 1;
-			},
-			_ => panic!("Tried to encrypt a message prior to noise handshake completion"),
-		}
-
+		self.encrypt_message_with_header_0s(&mut res.0);
 		res.0
 	}
 
@@ -557,9 +544,30 @@ impl PeerChannelEncryptor {
 	}
 }
 
+/// A buffer which stores an encoded message (including the two message-type bytes) with some
+/// padding to allow for future encryption/MACing.
+pub struct MessageBuf(Vec<u8>);
+impl MessageBuf {
+	/// Creates a new buffer from an encoded message (i.e. the two message-type bytes followed by
+	/// the message contents).
+	///
+	/// Panics if the message is longer than 2^16.
+	pub fn from_encoded(encoded_msg: &[u8]) -> Self {
+		if encoded_msg.len() > LN_MAX_MSG_LEN {
+			panic!("Attempted to encrypt message longer than 65535 bytes!");
+		}
+		// In addition to the message (continaing the two message type bytes), we also have to add
+		// the message length header (and its MAC) and the message MAC.
+		let mut res = Vec::with_capacity(encoded_msg.len() + 16*2 + 2);
+		res.resize(encoded_msg.len() + 16 + 2, 0);
+		res[16 + 2..].copy_from_slice(&encoded_msg);
+		Self(res)
+	}
+}
+
 #[cfg(test)]
 mod tests {
-	use super::LN_MAX_MSG_LEN;
+	use super::{MessageBuf, LN_MAX_MSG_LEN};
 
 	use bitcoin::secp256k1::{PublicKey, SecretKey};
 	use bitcoin::secp256k1::Secp256k1;
@@ -775,7 +783,7 @@ mod tests {
 
 		for i in 0..1005 {
 			let msg = [0x68, 0x65, 0x6c, 0x6c, 0x6f];
-			let mut res = outbound_peer.encrypt_buffer(&msg);
+			let mut res = outbound_peer.encrypt_buffer(MessageBuf::from_encoded(&msg));
 			assert_eq!(res.len(), 5 + 2*16 + 2);
 
 			let len_header = res[0..2+16].to_vec();
@@ -811,7 +819,7 @@ mod tests {
 	fn max_message_len_encryption() {
 		let mut outbound_peer = get_outbound_peer_for_initiator_test_vectors();
 		let msg = [4u8; LN_MAX_MSG_LEN + 1];
-		outbound_peer.encrypt_buffer(&msg);
+		outbound_peer.encrypt_buffer(MessageBuf::from_encoded(&msg));
 	}
 
 	#[test]