// Copyright 2015-2017 Parity Technologies (UK) Ltd.
// This file is part of Parity.

// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Parity.  If not, see <http://www.gnu.org/licenses/>.

use std::sync::Arc;
use rand::random;
use hash::write_keccak;
use mio::tcp::*;
use bigint::hash::*;
use ethcore_bytes::Bytes;
use rlp::*;
use connection::{Connection};
use host::{HostInfo};
use node_table::NodeId;
use stats::NetworkStats;
use io::{IoContext, StreamToken};
use ethkey::{KeyPair, Public, Secret, recover, sign, Generator, Random};
use crypto::{ecdh, ecies};
use error::{Error, ErrorKind};

#[derive(PartialEq, Eq, Debug)]
enum HandshakeState {
	/// Just created
	New,
	/// Waiting for auth packet
	ReadingAuth,
	/// Waiting for extended auth packet
	ReadingAuthEip8,
	/// Waiting for ack packet
	ReadingAck,
	/// Waiting for extended ack packet
	ReadingAckEip8,
	/// Ready to start a session
	StartSession,
}

/// `RLPx` protocol handhake. See https://github.com/ethereum/devp2p/blob/master/rlpx.md#encrypted-handshake
pub struct Handshake {
	/// Remote node public key
	pub id: NodeId,
	/// Underlying connection
	pub connection: Connection,
	/// Handshake state
	state: HandshakeState,
	/// Outgoing or incoming connection
	pub originated: bool,
	/// ECDH ephemeral
	pub ecdhe: KeyPair,
	/// Connection nonce
	pub nonce: H256,
	/// Handshake public key
	pub remote_ephemeral: Public,
	/// Remote connection nonce.
	pub remote_nonce: H256,
	/// Remote `RLPx` protocol version.
	pub remote_version: u64,
	/// A copy of received encryped auth packet
	pub auth_cipher: Bytes,
	/// A copy of received encryped ack packet
	pub ack_cipher: Bytes,
	/// This Handshake is marked for deleteion flag
	pub expired: bool,
}

const V4_AUTH_PACKET_SIZE: usize = 307;
const V4_ACK_PACKET_SIZE: usize = 210;
const HANDSHAKE_TIMEOUT: u64 = 5000;
const PROTOCOL_VERSION: u64 = 4;
// Amount of bytes added when encrypting with encryptECIES.
const ECIES_OVERHEAD: usize = 113;

impl Handshake {
	/// Create a new handshake object
	pub fn new(token: StreamToken, id: Option<&NodeId>, socket: TcpStream, nonce: &H256, stats: Arc<NetworkStats>) -> Result<Handshake, Error> {
		Ok(Handshake {
			id: if let Some(id) = id { id.clone()} else { NodeId::new() },
			connection: Connection::new(token, socket, stats),
			originated: false,
			state: HandshakeState::New,
			ecdhe: Random.generate()?,
			nonce: nonce.clone(),
			remote_ephemeral: Public::new(),
			remote_nonce: H256::new(),
			remote_version: PROTOCOL_VERSION,
			auth_cipher: Bytes::new(),
			ack_cipher: Bytes::new(),
			expired: false,
		})
	}

	/// Check if this handshake is expired.
	pub fn expired(&self) -> bool {
		self.expired
	}

	/// Start a handhsake
	pub fn start<Message>(&mut self, io: &IoContext<Message>, host: &HostInfo, originated: bool) -> Result<(), Error> where Message: Send + Clone+ Sync + 'static {
		self.originated = originated;
		io.register_timer(self.connection.token, HANDSHAKE_TIMEOUT).ok();
		if originated {
			self.write_auth(io, host.secret(), host.id())?;
		}
		else {
			self.state = HandshakeState::ReadingAuth;
			self.connection.expect(V4_AUTH_PACKET_SIZE);
		};
		Ok(())
	}

	/// Check if handshake is complete
	pub fn done(&self) -> bool {
		self.state == HandshakeState::StartSession
	}

	/// Readable IO handler. Drives the state change.
	pub fn readable<Message>(&mut self, io: &IoContext<Message>, host: &HostInfo) -> Result<(), Error> where Message: Send + Clone + Sync + 'static {
		if !self.expired() {
			while let Some(data) = self.connection.readable()? {
				match self.state {
					HandshakeState::New => {},
					HandshakeState::StartSession => {},
					HandshakeState::ReadingAuth => {
						self.read_auth(io, host.secret(), &data)?;
					},
					HandshakeState::ReadingAuthEip8 => {
						self.read_auth_eip8(io, host.secret(), &data)?;
					},
					HandshakeState::ReadingAck => {
						self.read_ack(host.secret(), &data)?;
					},
					HandshakeState::ReadingAckEip8 => {
						self.read_ack_eip8(host.secret(), &data)?;
					},
				}
				if self.state == HandshakeState::StartSession {
					io.clear_timer(self.connection.token).ok();
					break;
				}
			}
		}
		Ok(())
	}

	/// Writabe IO handler.
	pub fn writable<Message>(&mut self, io: &IoContext<Message>) -> Result<(), Error> where Message: Send + Clone + Sync + 'static {
		if !self.expired() {
			self.connection.writable(io)?;
		}
		Ok(())
	}

	fn set_auth(&mut self, host_secret: &Secret, sig: &[u8], remote_public: &[u8], remote_nonce: &[u8], remote_version: u64) -> Result<(), Error> {
		self.id.clone_from_slice(remote_public);
		self.remote_nonce.clone_from_slice(remote_nonce);
		self.remote_version = remote_version;
		let shared = *ecdh::agree(host_secret, &self.id)?;
		let signature = H520::from_slice(sig);
		self.remote_ephemeral = recover(&signature.into(), &(&shared ^ &self.remote_nonce))?;
		Ok(())
	}

	/// Parse, validate and confirm auth message
	fn read_auth<Message>(&mut self, io: &IoContext<Message>, secret: &Secret, data: &[u8]) -> Result<(), Error> where Message: Send + Clone + Sync + 'static {
		trace!(target: "network", "Received handshake auth from {:?}", self.connection.remote_addr_str());
		if data.len() != V4_AUTH_PACKET_SIZE {
			debug!(target: "network", "Wrong auth packet size");
			return Err(ErrorKind::BadProtocol.into());
		}
		self.auth_cipher = data.to_vec();
		match ecies::decrypt(secret, &[], data) {
			Ok(auth) => {
				let (sig, rest) = auth.split_at(65);
				let (_, rest) = rest.split_at(32);
				let (pubk, rest) = rest.split_at(64);
				let (nonce, _) = rest.split_at(32);
				self.set_auth(secret, sig, pubk, nonce, PROTOCOL_VERSION)?;
				self.write_ack(io)?;
			}
			Err(_) => {
				// Try to interpret as EIP-8 packet
				let total = (((data[0] as u16) << 8 | (data[1] as u16)) as usize) + 2;
				if total < V4_AUTH_PACKET_SIZE {
					debug!(target: "network", "Wrong EIP8 auth packet size");
					return Err(ErrorKind::BadProtocol.into());
				}
				let rest = total - data.len();
				self.state = HandshakeState::ReadingAuthEip8;
				self.connection.expect(rest);
			}
		}
		Ok(())
	}

	fn read_auth_eip8<Message>(&mut self, io: &IoContext<Message>, secret: &Secret, data: &[u8]) -> Result<(), Error> where Message: Send + Clone + Sync + 'static {
		trace!(target: "network", "Received EIP8 handshake auth from {:?}", self.connection.remote_addr_str());
		self.auth_cipher.extend_from_slice(data);
		let auth = ecies::decrypt(secret, &self.auth_cipher[0..2], &self.auth_cipher[2..])?;
		let rlp = UntrustedRlp::new(&auth);
		let signature: H520 = rlp.val_at(0)?;
		let remote_public: Public = rlp.val_at(1)?;
		let remote_nonce: H256 = rlp.val_at(2)?;
		let remote_version: u64 = rlp.val_at(3)?;
		self.set_auth(secret, &signature, &remote_public, &remote_nonce, remote_version)?;
		self.write_ack_eip8(io)?;
		Ok(())
	}

	/// Parse and validate ack message
	fn read_ack(&mut self, secret: &Secret, data: &[u8]) -> Result<(), Error> {
		trace!(target: "network", "Received handshake ack from {:?}", self.connection.remote_addr_str());
		if data.len() != V4_ACK_PACKET_SIZE {
			debug!(target: "network", "Wrong ack packet size");
			return Err(ErrorKind::BadProtocol.into());
		}
		self.ack_cipher = data.to_vec();
		match ecies::decrypt(secret, &[], data) {
			Ok(ack) => {
				self.remote_ephemeral.clone_from_slice(&ack[0..64]);
				self.remote_nonce.clone_from_slice(&ack[64..(64+32)]);
				self.state = HandshakeState::StartSession;
			}
			Err(_) => {
				// Try to interpret as EIP-8 packet
				let total = (((data[0] as u16) << 8 | (data[1] as u16)) as usize) + 2;
				if total < V4_ACK_PACKET_SIZE {
					debug!(target: "network", "Wrong EIP8 ack packet size");
					return Err(ErrorKind::BadProtocol.into());
				}
				let rest = total - data.len();
				self.state = HandshakeState::ReadingAckEip8;
				self.connection.expect(rest);
			}
		}
		Ok(())
	}

	fn read_ack_eip8(&mut self, secret: &Secret, data: &[u8]) -> Result<(), Error> {
		trace!(target: "network", "Received EIP8 handshake auth from {:?}", self.connection.remote_addr_str());
		self.ack_cipher.extend_from_slice(data);
		let ack = ecies::decrypt(secret, &self.ack_cipher[0..2], &self.ack_cipher[2..])?;
		let rlp = UntrustedRlp::new(&ack);
		self.remote_ephemeral = rlp.val_at(0)?;
		self.remote_nonce = rlp.val_at(1)?;
		self.remote_version = rlp.val_at(2)?;
		self.state = HandshakeState::StartSession;
		Ok(())
	}

	/// Sends auth message
	fn write_auth<Message>(&mut self, io: &IoContext<Message>, secret: &Secret, public: &Public) -> Result<(), Error> where Message: Send + Clone + Sync + 'static {
		trace!(target: "network", "Sending handshake auth to {:?}", self.connection.remote_addr_str());
		let mut data = [0u8; /*Signature::SIZE*/ 65 + /*H256::SIZE*/ 32 + /*Public::SIZE*/ 64 + /*H256::SIZE*/ 32 + 1]; //TODO: use associated constants
		let len = data.len();
		{
			data[len - 1] = 0x0;
			let (sig, rest) = data.split_at_mut(65);
			let (hepubk, rest) = rest.split_at_mut(32);
			let (pubk, rest) = rest.split_at_mut(64);
			let (nonce, _) = rest.split_at_mut(32);

			// E(remote-pubk, S(ecdhe-random, ecdh-shared-secret^nonce) || H(ecdhe-random-pubk) || pubk || nonce || 0x0)
			let shared = *ecdh::agree(secret, &self.id)?;
			sig.copy_from_slice(&*sign(self.ecdhe.secret(), &(&shared ^ &self.nonce))?);
			write_keccak(self.ecdhe.public(), hepubk);
			pubk.copy_from_slice(public);
			nonce.copy_from_slice(&self.nonce);
		}
		let message = ecies::encrypt(&self.id, &[], &data)?;
		self.auth_cipher = message.clone();
		self.connection.send(io, message);
		self.connection.expect(V4_ACK_PACKET_SIZE);
		self.state = HandshakeState::ReadingAck;
		Ok(())
	}

	/// Sends ack message
	fn write_ack<Message>(&mut self, io: &IoContext<Message>) -> Result<(), Error> where Message: Send + Clone + Sync + 'static {
		trace!(target: "network", "Sending handshake ack to {:?}", self.connection.remote_addr_str());
		let mut data = [0u8; 1 + /*Public::SIZE*/ 64 + /*H256::SIZE*/ 32]; //TODO: use associated constants
		let len = data.len();
		{
			data[len - 1] = 0x0;
			let (epubk, rest) = data.split_at_mut(64);
			let (nonce, _) = rest.split_at_mut(32);
			self.ecdhe.public().copy_to(epubk);
			self.nonce.copy_to(nonce);
		}
		let message = ecies::encrypt(&self.id, &[], &data)?;
		self.ack_cipher = message.clone();
		self.connection.send(io, message);
		self.state = HandshakeState::StartSession;
		Ok(())
	}

	/// Sends EIP8 ack message
	fn write_ack_eip8<Message>(&mut self, io: &IoContext<Message>) -> Result<(), Error> where Message: Send + Clone + Sync + 'static {
		trace!(target: "network", "Sending EIP8 handshake ack to {:?}", self.connection.remote_addr_str());
		let mut rlp = RlpStream::new_list(3);
		rlp.append(self.ecdhe.public());
		rlp.append(&self.nonce);
		rlp.append(&PROTOCOL_VERSION);

		let pad_array = [0u8; 200];
		let pad = &pad_array[0 .. 100 + random::<usize>() % 100];
		rlp.append_raw(pad, 0);

		let encoded = rlp.drain();
		let len = (encoded.len() + ECIES_OVERHEAD) as u16;
		let prefix = [ (len >> 8) as u8, (len & 0xff) as u8 ];
		let message = ecies::encrypt(&self.id, &prefix, &encoded)?;
		self.ack_cipher.extend_from_slice(&prefix);
		self.ack_cipher.extend_from_slice(&message);
		self.connection.send(io, self.ack_cipher.clone());
		self.state = HandshakeState::StartSession;
		Ok(())
	}
}

#[cfg(test)]
mod test {
	use std::sync::Arc;
	use rustc_hex::FromHex;
	use super::*;
	use bigint::hash::H256;
	use io::*;
	use mio::tcp::TcpStream;
	use stats::NetworkStats;
	use ethkey::Public;

	fn check_auth(h: &Handshake, version: u64) {
		assert_eq!(h.id, "fda1cff674c90c9a197539fe3dfb53086ace64f83ed7c6eabec741f7f381cc803e52ab2cd55d5569bce4347107a310dfd5f88a010cd2ffd1005ca406f1842877".into());
		assert_eq!(h.remote_nonce, "7e968bba13b6c50e2c4cd7f241cc0d64d1ac25c7f5952df231ac6a2bda8ee5d6".into());
		assert_eq!(h.remote_ephemeral, "654d1044b69c577a44e5f01a1209523adb4026e70c62d1c13a067acabc09d2667a49821a0ad4b634554d330a15a58fe61f8a8e0544b310c6de7b0c8da7528a8d".into());
		assert_eq!(h.remote_version, version);
	}

	fn check_ack(h: &Handshake, version: u64) {
		assert_eq!(h.remote_nonce, "559aead08264d5795d3909718cdd05abd49572e84fe55590eef31a88a08fdffd".into());
		assert_eq!(h.remote_ephemeral, "b6d82fa3409da933dbf9cb0140c5dde89f4e64aec88d476af648880f4a10e1e49fe35ef3e69e93dd300b4797765a747c6384a6ecf5db9c2690398607a86181e4".into());
		assert_eq!(h.remote_version, version);
	}

	fn create_handshake(to: Option<&Public>) -> Handshake {
		let addr = "127.0.0.1:50556".parse().unwrap();
		let socket = TcpStream::connect(&addr).unwrap();
		let nonce = H256::new();
		Handshake::new(0, to, socket, &nonce, Arc::new(NetworkStats::new())).unwrap()
	}

	fn test_io() -> IoContext<i32> {
		IoContext::new(IoChannel::disconnected(), 0)
	}

	#[test]
	fn test_handshake_auth_plain() {
		let mut h = create_handshake(None);
		let secret = "b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291".parse().unwrap();
		let auth =
			"\
			048ca79ad18e4b0659fab4853fe5bc58eb83992980f4c9cc147d2aa31532efd29a3d3dc6a3d89eaf\
			913150cfc777ce0ce4af2758bf4810235f6e6ceccfee1acc6b22c005e9e3a49d6448610a58e98744\
			ba3ac0399e82692d67c1f58849050b3024e21a52c9d3b01d871ff5f210817912773e610443a9ef14\
			2e91cdba0bd77b5fdf0769b05671fc35f83d83e4d3b0b000c6b2a1b1bba89e0fc51bf4e460df3105\
			c444f14be226458940d6061c296350937ffd5e3acaceeaaefd3c6f74be8e23e0f45163cc7ebd7622\
			0f0128410fd05250273156d548a414444ae2f7dea4dfca2d43c057adb701a715bf59f6fb66b2d1d2\
			0f2c703f851cbf5ac47396d9ca65b6260bd141ac4d53e2de585a73d1750780db4c9ee4cd4d225173\
			a4592ee77e2bd94d0be3691f3b406f9bba9b591fc63facc016bfa8\
			".from_hex().unwrap();

		h.read_auth(&test_io(), &secret, &auth).unwrap();
		assert_eq!(h.state, super::HandshakeState::StartSession);
		check_auth(&h, 4);
	}

	#[test]
	fn test_handshake_auth_eip8() {
		let mut h = create_handshake(None);
		let secret = "b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291".parse().unwrap();
		let auth =
			"\
			01b304ab7578555167be8154d5cc456f567d5ba302662433674222360f08d5f1534499d3678b513b\
			0fca474f3a514b18e75683032eb63fccb16c156dc6eb2c0b1593f0d84ac74f6e475f1b8d56116b84\
			9634a8c458705bf83a626ea0384d4d7341aae591fae42ce6bd5c850bfe0b999a694a49bbbaf3ef6c\
			da61110601d3b4c02ab6c30437257a6e0117792631a4b47c1d52fc0f8f89caadeb7d02770bf999cc\
			147d2df3b62e1ffb2c9d8c125a3984865356266bca11ce7d3a688663a51d82defaa8aad69da39ab6\
			d5470e81ec5f2a7a47fb865ff7cca21516f9299a07b1bc63ba56c7a1a892112841ca44b6e0034dee\
			70c9adabc15d76a54f443593fafdc3b27af8059703f88928e199cb122362a4b35f62386da7caad09\
			c001edaeb5f8a06d2b26fb6cb93c52a9fca51853b68193916982358fe1e5369e249875bb8d0d0ec3\
			6f917bc5e1eafd5896d46bd61ff23f1a863a8a8dcd54c7b109b771c8e61ec9c8908c733c0263440e\
			2aa067241aaa433f0bb053c7b31a838504b148f570c0ad62837129e547678c5190341e4f1693956c\
			3bf7678318e2d5b5340c9e488eefea198576344afbdf66db5f51204a6961a63ce072c8926c\
			".from_hex().unwrap();

		h.read_auth(&test_io(), &secret, &auth[0..super::V4_AUTH_PACKET_SIZE]).unwrap();
		assert_eq!(h.state, super::HandshakeState::ReadingAuthEip8);
		h.read_auth_eip8(&test_io(), &secret, &auth[super::V4_AUTH_PACKET_SIZE..]).unwrap();
		assert_eq!(h.state, super::HandshakeState::StartSession);
		check_auth(&h, 4);
	}

	#[test]
	fn test_handshake_auth_eip8_2() {
		let mut h = create_handshake(None);
		let secret = "b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291".parse().unwrap();
		let auth =
			"\
			01b8044c6c312173685d1edd268aa95e1d495474c6959bcdd10067ba4c9013df9e40ff45f5bfd6f7\
			2471f93a91b493f8e00abc4b80f682973de715d77ba3a005a242eb859f9a211d93a347fa64b597bf\
			280a6b88e26299cf263b01b8dfdb712278464fd1c25840b995e84d367d743f66c0e54a586725b7bb\
			f12acca27170ae3283c1073adda4b6d79f27656993aefccf16e0d0409fe07db2dc398a1b7e8ee93b\
			cd181485fd332f381d6a050fba4c7641a5112ac1b0b61168d20f01b479e19adf7fdbfa0905f63352\
			bfc7e23cf3357657455119d879c78d3cf8c8c06375f3f7d4861aa02a122467e069acaf513025ff19\
			6641f6d2810ce493f51bee9c966b15c5043505350392b57645385a18c78f14669cc4d960446c1757\
			1b7c5d725021babbcd786957f3d17089c084907bda22c2b2675b4378b114c601d858802a55345a15\
			116bc61da4193996187ed70d16730e9ae6b3bb8787ebcaea1871d850997ddc08b4f4ea668fbf3740\
			7ac044b55be0908ecb94d4ed172ece66fd31bfdadf2b97a8bc690163ee11f5b575a4b44e36e2bfb2\
			f0fce91676fd64c7773bac6a003f481fddd0bae0a1f31aa27504e2a533af4cef3b623f4791b2cca6\
			d490\
			".from_hex().unwrap();

		h.read_auth(&test_io(), &secret, &auth[0..super::V4_AUTH_PACKET_SIZE]).unwrap();
		assert_eq!(h.state, super::HandshakeState::ReadingAuthEip8);
		h.read_auth_eip8(&test_io(), &secret, &auth[super::V4_AUTH_PACKET_SIZE..]).unwrap();
		assert_eq!(h.state, super::HandshakeState::StartSession);
		check_auth(&h, 56);
		let ack = h.ack_cipher.clone();
		let total = (((ack[0] as u16) << 8 | (ack[1] as u16)) as usize) + 2;
		assert_eq!(ack.len(), total);
	}

	#[test]
	fn test_handshake_ack_plain() {
		let remote = "fda1cff674c90c9a197539fe3dfb53086ace64f83ed7c6eabec741f7f381cc803e52ab2cd55d5569bce4347107a310dfd5f88a010cd2ffd1005ca406f1842877".into();
		let mut h = create_handshake(Some(&remote));
		let secret = "49a7b37aa6f6645917e7b807e9d1c00d4fa71f18343b0d4122a4d2df64dd6fee".parse().unwrap();
		let ack =
			"\
			049f8abcfa9c0dc65b982e98af921bc0ba6e4243169348a236abe9df5f93aa69d99cadddaa387662\
			b0ff2c08e9006d5a11a278b1b3331e5aaabf0a32f01281b6f4ede0e09a2d5f585b26513cb794d963\
			5a57563921c04a9090b4f14ee42be1a5461049af4ea7a7f49bf4c97a352d39c8d02ee4acc416388c\
			1c66cec761d2bc1c72da6ba143477f049c9d2dde846c252c111b904f630ac98e51609b3b1f58168d\
			dca6505b7196532e5f85b259a20c45e1979491683fee108e9660edbf38f3add489ae73e3dda2c71b\
			d1497113d5c755e942d1\
			".from_hex().unwrap();

		h.read_ack(&secret, &ack).unwrap();
		assert_eq!(h.state, super::HandshakeState::StartSession);
		check_ack(&h, 4);
	}

	#[test]
	fn test_handshake_ack_eip8() {
		let remote = "fda1cff674c90c9a197539fe3dfb53086ace64f83ed7c6eabec741f7f381cc803e52ab2cd55d5569bce4347107a310dfd5f88a010cd2ffd1005ca406f1842877".into();
		let mut h = create_handshake(Some(&remote));
		let secret = "49a7b37aa6f6645917e7b807e9d1c00d4fa71f18343b0d4122a4d2df64dd6fee".parse().unwrap();
		let ack =
			"\
			01ea0451958701280a56482929d3b0757da8f7fbe5286784beead59d95089c217c9b917788989470\
			b0e330cc6e4fb383c0340ed85fab836ec9fb8a49672712aeabbdfd1e837c1ff4cace34311cd7f4de\
			05d59279e3524ab26ef753a0095637ac88f2b499b9914b5f64e143eae548a1066e14cd2f4bd7f814\
			c4652f11b254f8a2d0191e2f5546fae6055694aed14d906df79ad3b407d94692694e259191cde171\
			ad542fc588fa2b7333313d82a9f887332f1dfc36cea03f831cb9a23fea05b33deb999e85489e645f\
			6aab1872475d488d7bd6c7c120caf28dbfc5d6833888155ed69d34dbdc39c1f299be1057810f34fb\
			e754d021bfca14dc989753d61c413d261934e1a9c67ee060a25eefb54e81a4d14baff922180c395d\
			3f998d70f46f6b58306f969627ae364497e73fc27f6d17ae45a413d322cb8814276be6ddd13b885b\
			201b943213656cde498fa0e9ddc8e0b8f8a53824fbd82254f3e2c17e8eaea009c38b4aa0a3f306e8\
			797db43c25d68e86f262e564086f59a2fc60511c42abfb3057c247a8a8fe4fb3ccbadde17514b7ac\
			8000cdb6a912778426260c47f38919a91f25f4b5ffb455d6aaaf150f7e5529c100ce62d6d92826a7\
			1778d809bdf60232ae21ce8a437eca8223f45ac37f6487452ce626f549b3b5fdee26afd2072e4bc7\
			5833c2464c805246155289f4\
			".from_hex().unwrap();

		h.read_ack(&secret, &ack[0..super::V4_ACK_PACKET_SIZE]).unwrap();
		assert_eq!(h.state, super::HandshakeState::ReadingAckEip8);
		h.read_ack_eip8(&secret, &ack[super::V4_ACK_PACKET_SIZE..]).unwrap();
		assert_eq!(h.state, super::HandshakeState::StartSession);
		check_ack(&h, 4);
	}

	#[test]
	fn test_handshake_ack_eip8_2() {
		let remote = "fda1cff674c90c9a197539fe3dfb53086ace64f83ed7c6eabec741f7f381cc803e52ab2cd55d5569bce4347107a310dfd5f88a010cd2ffd1005ca406f1842877".into();
		let mut h = create_handshake(Some(&remote));
		let secret = "49a7b37aa6f6645917e7b807e9d1c00d4fa71f18343b0d4122a4d2df64dd6fee".parse().unwrap();
		let ack =
			"\
			01f004076e58aae772bb101ab1a8e64e01ee96e64857ce82b1113817c6cdd52c09d26f7b90981cd7\
			ae835aeac72e1573b8a0225dd56d157a010846d888dac7464baf53f2ad4e3d584531fa203658fab0\
			3a06c9fd5e35737e417bc28c1cbf5e5dfc666de7090f69c3b29754725f84f75382891c561040ea1d\
			dc0d8f381ed1b9d0d4ad2a0ec021421d847820d6fa0ba66eaf58175f1b235e851c7e2124069fbc20\
			2888ddb3ac4d56bcbd1b9b7eab59e78f2e2d400905050f4a92dec1c4bdf797b3fc9b2f8e84a482f3\
			d800386186712dae00d5c386ec9387a5e9c9a1aca5a573ca91082c7d68421f388e79127a5177d4f8\
			590237364fd348c9611fa39f78dcdceee3f390f07991b7b47e1daa3ebcb6ccc9607811cb17ce51f1\
			c8c2c5098dbdd28fca547b3f58c01a424ac05f869f49c6a34672ea2cbbc558428aa1fe48bbfd6115\
			8b1b735a65d99f21e70dbc020bfdface9f724a0d1fb5895db971cc81aa7608baa0920abb0a565c9c\
			436e2fd13323428296c86385f2384e408a31e104670df0791d93e743a3a5194ee6b076fb6323ca59\
			3011b7348c16cf58f66b9633906ba54a2ee803187344b394f75dd2e663a57b956cb830dd7a908d4f\
			39a2336a61ef9fda549180d4ccde21514d117b6c6fd07a9102b5efe710a32af4eeacae2cb3b1dec0\
			35b9593b48b9d3ca4c13d245d5f04169b0b1\
			".from_hex().unwrap();

		h.read_ack(&secret, &ack[0..super::V4_ACK_PACKET_SIZE]).unwrap();
		assert_eq!(h.state, super::HandshakeState::ReadingAckEip8);
		h.read_ack_eip8(&secret, &ack[super::V4_ACK_PACKET_SIZE..]).unwrap();
		assert_eq!(h.state, super::HandshakeState::StartSession);
		check_ack(&h, 57);
	}
}