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path: root/src/protocol.rs
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use std::net::{TcpStream, ToSocketAddrs};
use std::time::Duration;
use std::io::{Read, Write};
use std::cmp;
use std::fmt::Display;
use sodiumoxide::crypto::stream::*;
use rand::{OsRng, Rng};
use protobuf::Message;
use protobuf::parse_from_bytes;
use integer_encoding::{VarIntReader, VarIntWriter};

use errors::*;
use network_msgs::*;
use make_discovery_key;

#[derive(Debug)]
pub enum DatNetMessage {
    Feed(Feed),
    Handshake(Handshake),
    Info(Info),
    Have(Have),
    Unhave(Unhave),
    Want(Want),
    Unwant(Unwant),
    Request(Request),
    Cancel(Cancel),
    Data(Data),
}

fn msg_code(msg: &DatNetMessage) -> u8 {
    match msg {
        &DatNetMessage::Feed(_) => 0,
        &DatNetMessage::Handshake(_) => 1,
        &DatNetMessage::Info(_) => 2,
        &DatNetMessage::Have(_) => 3,
        &DatNetMessage::Unhave(_) => 4,
        &DatNetMessage::Want(_) => 5,
        &DatNetMessage::Unwant(_) => 6,
        &DatNetMessage::Request(_) => 7,
        &DatNetMessage::Cancel(_) => 8,
        &DatNetMessage::Data(_) => 9,
    }
}

fn msg_sugar(msg: &DatNetMessage) -> &Message {
    match msg {
        &DatNetMessage::Feed(ref m) => m,
        &DatNetMessage::Handshake(ref m) => m,
        &DatNetMessage::Info(ref m) => m,
        &DatNetMessage::Have(ref m) => m,
        &DatNetMessage::Unhave(ref m) => m,
        &DatNetMessage::Want(ref m) => m,
        &DatNetMessage::Unwant(ref m) => m,
        &DatNetMessage::Request(ref m) => m,
        &DatNetMessage::Cancel(ref m) => m,
        &DatNetMessage::Data(ref m) => m,
    }
}

/// This helper is pretty slow/inefficient; lots of copying memory
fn bytewise_stream_xor_ic_inplace(buf: &mut [u8], byte_offset: u64, nonce: &Nonce, key: &Key) {
    // TODO: switch to new stream_xor_ic_inplace() variant?
    let mut offset = byte_offset;

    // We may have a partial-64-byte-block to finish encrypting first
    let partial_offset: usize = (offset % 64) as usize;
    let partial_len: usize = cmp::min(64 - partial_offset, buf.len());
    if partial_len != 0 {
        let mut partial = vec![0; 64];
        for i in 0..partial_len {
            partial[partial_offset + i] = buf[i];
        }
        let partial_enc = stream_xor_ic(&partial, &nonce, offset / 64, &key);
        offset += partial_len as u64;
        for i in 0..partial_len {
            buf[i] = partial_enc[partial_offset + i];
        }
    }
    if buf.len() > partial_len {
        let main_enc = stream_xor_ic(&buf[partial_len..], &nonce, offset / 64, &key);
        //offset += main_enc.len() as u64;
        for i in 0..main_enc.len() {
            buf[partial_len + i] = main_enc[i];
        }
    }
}

#[test]
fn test_bsxii_short() {
    let nonce = gen_nonce();
    let key = gen_key();

    for size in [10, 100, 1234].iter() {
        let mut a = vec![7; *size];
        let mut b = vec![7; *size];
        let c = vec![7; *size];

        assert_eq!(a, b);
        bytewise_stream_xor_ic_inplace(&mut a, 0, &nonce, &key);
        bytewise_stream_xor_ic_inplace(&mut b, 0, &nonce, &key);
        assert_eq!(a, b);
        assert_ne!(a, c);
        bytewise_stream_xor_ic_inplace(&mut a, 0, &nonce, &key);
        assert_eq!(a, c);
    }
}

#[test]
fn test_bsxii_continued() {
    let nonce = gen_nonce();
    let key = gen_key();

    let mut a = vec![7; 1234];
    let mut b = vec![7; 1234];
    let c = vec![7; 1234];

    assert_eq!(a, b);
    bytewise_stream_xor_ic_inplace(&mut a[0..10], 0, &nonce, &key);
    bytewise_stream_xor_ic_inplace(&mut a[10..20], 10, &nonce, &key);
    bytewise_stream_xor_ic_inplace(&mut b[0..20], 0, &nonce, &key);
    assert_eq!(a, b);
    bytewise_stream_xor_ic_inplace(&mut a[20..50], 20, &nonce, &key);
    bytewise_stream_xor_ic_inplace(&mut a[50..500], 50, &nonce, &key);
    bytewise_stream_xor_ic_inplace(&mut b[20..500], 20, &nonce, &key);
    assert_ne!(a, c);
    assert_eq!(a, b);
    bytewise_stream_xor_ic_inplace(&mut a[500..1234], 500, &nonce, &key);
    bytewise_stream_xor_ic_inplace(&mut a, 0, &nonce, &key);
    assert_eq!(a, c);
}

/// Represents a bi-directional connection to a network peer
///
/// Spec says nonce is 32 bytes, by dat implementation (hypercore-protocol) is 24 bytes.
pub struct DatConnection {
    pub id: [u8; 32],
    remote_id: [u8; 32],
    pub tcp: TcpStream,
    pub live: bool,
    pub key: Key,
    pub discovery_key: [u8; 32],
    tx_nonce: Nonce,
    tx_offset: u64,
    rx_nonce: Nonce,
    rx_offset: u64,
}

impl Read for DatConnection {
    /// Encrypted TCP read (after connection initialized). Uses XOR of an XSalsa20 stream, using
    /// block offsets.
    fn read(&mut self, buf: &mut [u8]) -> ::std::io::Result<usize> {
        let len = self.tcp.read(buf)?;
        bytewise_stream_xor_ic_inplace(&mut buf[0..len], self.rx_offset, &self.rx_nonce, &self.key);
        self.rx_offset += len as u64;

        Ok(len)
    }
}

impl Write for DatConnection {
    /// Encrypted write to complement `read()`.
    fn write(&mut self, buf: &[u8]) -> ::std::io::Result<usize> {
        // Don't mutate what we've been passed
        let mut enc = vec![0; buf.len()];
        enc.copy_from_slice(buf);

        bytewise_stream_xor_ic_inplace(&mut enc, self.tx_offset, &self.tx_nonce, &self.key);
        self.tx_offset += enc.len() as u64;

        self.tcp.write(&enc)
    }

    fn flush(&mut self) -> ::std::io::Result<()> {
        self.tcp.flush()
    }
}

impl Clone for DatConnection {
    fn clone(&self) -> DatConnection {
        DatConnection {
            id: self.id.clone(),
            remote_id: self.remote_id.clone(),
            tcp: self.tcp.try_clone().unwrap(),
            live: self.live,
            key: self.key.clone(),
            discovery_key: self.discovery_key.clone(),
            tx_nonce: self.tx_nonce.clone(),
            tx_offset: self.tx_offset,
            rx_nonce: self.rx_nonce.clone(),
            rx_offset: self.rx_offset,

        }
    }
}

impl DatConnection {
    pub fn connect<A: ToSocketAddrs + Display>(addr: A, key: &Key, live: bool, local_id: Option<&[u8]>) -> Result<DatConnection> {

        // Connect to server
        info!("Connecting to {}", addr);
        // TODO: timeout on connect (socketaddr iterator dance)
        let tcp = TcpStream::connect(addr)?;

        DatConnection::from_tcp(tcp, key, live, local_id)
    }

    // It's sort of a hack, but this should be usable from an accept() as well as a connect()
    pub fn from_tcp(tcp: TcpStream, key: &Key, live: bool, local_id: Option<&[u8]>) -> Result<DatConnection> {

        let tx_nonce = gen_nonce();
        let mut rng = OsRng::new()?;
        let mut local_id = match local_id {
            Some(val) => {
                let mut buf = [0; 32];
                buf.copy_from_slice(val);
                buf
            },
            None => {
                let mut buf = [0; 32];
                rng.fill_bytes(&mut buf);
                buf
            },
        };

        let mut dk = [0; 32];
        dk.copy_from_slice(&make_discovery_key(&key[0..32])[0..32]);

        let timeout = Duration::new(7, 0);
        tcp.set_write_timeout(Some(timeout))?;

        let mut dc = DatConnection {
            id: local_id,
            tcp,
            live,
            remote_id: [0; 32],
            key: key.clone(),
            discovery_key: dk,
            tx_nonce: tx_nonce,
            tx_offset: 0,
            rx_nonce: gen_nonce(), // dummy
            rx_offset: 0,
        };

        // Exchange feed
        let mut feed_msg = Feed::new();
        feed_msg.set_discoveryKey(dc.discovery_key.to_vec());
        feed_msg.set_nonce((tx_nonce[0..24]).to_vec());
        dc.send_feed(&feed_msg)?;

        // read feed
        let registration = dc.recv_feed()?;
        if registration.get_discoveryKey()[0..32] != dk[..] {
            bail!("Remote peer not sharing same discovery key");
        }
        let rn = registration.get_nonce();
        dc.rx_nonce = Nonce::from_slice(&rn).unwrap();

        // send handshake
        let mut handshake_msg = Handshake::new();
        handshake_msg.set_live(dc.live);
        handshake_msg.set_id(dc.id.to_vec());
        dc.send_msg(&DatNetMessage::Handshake(handshake_msg), 0)?;

        // read handshake
        let (msg, feed_index) = dc.recv_msg()?;
        if feed_index == 1 {
            bail!("Expected metadata msg, not content");
        }
        if let DatNetMessage::Handshake(handshake) = msg {
            // TODO: more satisfying way to do this copy
            let hid = handshake.get_id();
            for i in 0..32 {
                dc.remote_id[i] = hid[i];
            }
        } else {
            bail!("Expected Handshake message, got something else");
        }

        Ok(dc)
    }

    /// For hyperdrive connections, `feed_index` is equivalent to a `is_content` boolean flag.
    pub fn send_msg(&mut self, dnm: &DatNetMessage, feed_index: u8) -> Result<()> {
        let header_int: u8 = (feed_index as u8) << 4 | (msg_code(dnm) & 0x0F);
        let msg: &Message = msg_sugar(dnm);
        let total_message_size = (msg.compute_size() as usize) + 1;

        trace!(
            "SEND total_len={}  header={}  feed_index={} type={:?}",
            total_message_size,
            header_int,
            feed_index,
            &dnm
        );

        // send both header varints, and data
        self.write_varint(total_message_size as u64)?;
        self.write_varint(header_int as u32)?;

        match dnm {
            &DatNetMessage::Feed(ref m) => m.write_to_writer(self)?,
            &DatNetMessage::Handshake(ref m) => m.write_to_writer(self)?,
            &DatNetMessage::Info(ref m) => m.write_to_writer(self)?,
            &DatNetMessage::Have(ref m) => m.write_to_writer(self)?,
            &DatNetMessage::Unhave(ref m) => m.write_to_writer(self)?,
            &DatNetMessage::Want(ref m) => m.write_to_writer(self)?,
            &DatNetMessage::Unwant(ref m) => m.write_to_writer(self)?,
            &DatNetMessage::Request(ref m) => m.write_to_writer(self)?,
            &DatNetMessage::Cancel(ref m) => m.write_to_writer(self)?,
            &DatNetMessage::Data(ref m) => m.write_to_writer(self)?,
        }
        Ok(())
    }

    /// Returns a tuple of the received message and the register index it corresponds to.
    pub fn recv_msg(&mut self) -> Result<(DatNetMessage, u8)> {
        let total_len: u64 = self.read_varint()?;
        let header: u8 = self.read_varint()?;

        let feed_index = (header >> 4) & 0xFF;

        trace!(
            "RECV total_len={}  header={}  feed_index={}",
            total_len,
            header,
            feed_index,
        );

        if header > 0x1F {
            bail!("Invalid header received: {}", header);
        }

        let msg_len = (total_len - 1) as usize;
        let mut buf = vec![0; msg_len];
        self.read_exact(&mut buf[0..msg_len])?;

        let dnm = match header & 0x0F {
            0 => DatNetMessage::Feed(parse_from_bytes::<Feed>(&mut buf)?),
            1 => DatNetMessage::Handshake(parse_from_bytes::<Handshake>(&mut buf)?),
            2 => DatNetMessage::Info(parse_from_bytes::<Info>(&mut buf)?),
            3 => DatNetMessage::Have(parse_from_bytes::<Have>(&mut buf)?),
            4 => DatNetMessage::Unhave(parse_from_bytes::<Unhave>(&mut buf)?),
            5 => DatNetMessage::Want(parse_from_bytes::<Want>(&mut buf)?),
            6 => DatNetMessage::Unwant(parse_from_bytes::<Unwant>(&mut buf)?),
            7 => DatNetMessage::Request(parse_from_bytes::<Request>(&mut buf)?),
            8 => DatNetMessage::Cancel(parse_from_bytes::<Cancel>(&mut buf)?),
            9 => DatNetMessage::Data(parse_from_bytes::<Data>(&mut buf)?),
            other => bail!("Unimplemented message type received: {}", other),
        };
        trace!("\twas: {:?}", &dnm);
        Ok((dnm, feed_index))
    }

    /// Special unencrypted variant of `send_msg()`, used only during initial connection
    /// establishment (eg, to check metadata discovery key and exchange nonces). After the
    /// connection is initialized, send Feed messages as normal to add extra feeds.
    fn send_feed(&mut self, reg: &Feed) -> Result<()> {
        // TODO: refactor this to take discovery key and nonce directly

        let header_int: u8 = 0;
        let total_message_size = (reg.compute_size() as usize) + 1;

        trace!(
            "SEND total_len={}  header={} msg={:?}",
            total_message_size,
            header_int,
            reg
        );

        self.tcp.write_varint(total_message_size as u64)?;
        self.tcp.write_varint(header_int as u32)?;
        reg.write_to_writer(&mut self.tcp)?;
        Ok(())
    }

    /// Receive complement to `send_feed()` (un-encrypted, used only during initial connection
    /// establishment).
    fn recv_feed(&mut self) -> Result<Feed> {

        let total_len: u64 = self.tcp.read_varint()?;
        let header: u8 = self.tcp.read_varint()?;

        if header != 0 {
            bail!("Invalid Feed header received");
        }

        trace!("RECV total_len={}  header={}", total_len, header);

        let msg_len = (total_len - 1) as usize;
        let mut buf = vec![0; msg_len];
        self.tcp.read_exact(&mut buf[0..msg_len])?;

        let reg = parse_from_bytes::<Feed>(&mut buf)?;
        trace!("\twas: {:?}", reg);
        Ok(reg)
    }
}