diff --git a/.gitignore b/.gitignore
index eb5a316..ecd64e4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,3 @@
 target
+Cargo.lock
+*.torrent
diff --git a/Cargo.toml b/Cargo.toml
index db3612b..e31d883 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -4,6 +4,8 @@ version = "0.1.0"
 authors = ["Simon Bernier St-Pierre <sbernierstpierre@gmail.com>"]
 
 [dependencies]
+byteorder = "0.5"
+libc = "0.2"
 sha1 = "0.2"
 url = "1.2"
 
diff --git a/design.md b/design.md
new file mode 100644
index 0000000..af00e71
--- /dev/null
+++ b/design.md
@@ -0,0 +1,8 @@
+* A torrent should have multiple workers (seed vs download workers?).
+* These workers work with connections, if one break they find another one.
+  * The connection broker manages connections, choking/unchoking.
+    * Connection are linked to a peer & their bitfield.
+    * Connections need to be listened to at all times for choke/unchoke/have/timeout/interested
+    * A worker takes over a connection to send/receive.
+  * The connection broker opens news connections if none are available for
+    the workers
diff --git a/examples/decode-torrent.rs b/examples/decode-torrent.rs
index 8969b8f..01ca503 100644
--- a/examples/decode-torrent.rs
+++ b/examples/decode-torrent.rs
@@ -3,12 +3,14 @@ extern crate magnolia;
 use std::env;
 use std::fs::File;
 use std::io::{self, Read};
+use std::thread;
+use std::time::Duration;
 use std::str;
 
 use magnolia::bencode::*;
 use magnolia::metainfo::Metainfo;
-use magnolia::torrent::Torrent;
 use magnolia::tracker::http;
+use magnolia::net::session::Session;
 
 fn load_file(path: &str) -> io::Result<()> {
     let mut buf = Vec::new();
@@ -18,16 +20,14 @@ fn load_file(path: &str) -> io::Result<()> {
     let obj = decode(&buf).unwrap();
     let meta = Metainfo::from_bencode(obj).unwrap();
 
-    let t = Torrent {
-        metainfo: meta,
-        uploaded: 0,
-        downloaded: 0,
-        left: 0,
-    };
+    println!("{}", meta.pieces.len());
 
-    let resp = http::get_peers([1u8; 20], 55555, &t).unwrap();
+    let s = Session::new();
+    s.add_torrent(meta);
 
-    print!("{:?}", resp);
+    loop {
+        thread::sleep(Duration::from_secs(1));
+    }
 
     Ok(())
 }
diff --git a/src/buffer.rs b/src/bencode/buffer.rs
similarity index 100%
rename from src/buffer.rs
rename to src/bencode/buffer.rs
diff --git a/src/bencode/decode.rs b/src/bencode/decode.rs
index 928bc1f..61a7ab9 100644
--- a/src/bencode/decode.rs
+++ b/src/bencode/decode.rs
@@ -3,7 +3,7 @@ use std::num::ParseIntError;
 use std::str::{self, Utf8Error};
 
 use bencode::{Bytes, Object};
-use buffer::Buffer;
+use bencode::buffer::Buffer;
 
 #[derive(Debug)]
 pub struct DecodeError;
diff --git a/src/bencode/mod.rs b/src/bencode/mod.rs
index 4b91daf..38d527e 100644
--- a/src/bencode/mod.rs
+++ b/src/bencode/mod.rs
@@ -1,3 +1,4 @@
+mod buffer;
 mod decode;
 mod encode;
 
diff --git a/src/lib.rs b/src/lib.rs
index 8421c35..7c9c340 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,9 +1,10 @@
+extern crate byteorder;
 extern crate hyper;
+extern crate libc;
 extern crate sha1;
 extern crate url;
 
 pub mod bencode;
-pub mod buffer;
 pub mod metainfo;
-pub mod torrent;
+pub mod net;
 pub mod tracker;
diff --git a/src/metainfo.rs b/src/metainfo.rs
index 69879ba..f48f9e9 100644
--- a/src/metainfo.rs
+++ b/src/metainfo.rs
@@ -1,3 +1,5 @@
+use std::fmt;
+use std::ops::{Deref, DerefMut};
 use std::path::PathBuf;
 
 use sha1::Sha1;
@@ -18,9 +20,11 @@ pub struct Metainfo {
     pub announce: String,
     pub announce_list: Vec<Vec<String>>,
     pub files: Vec<MetainfoFile>,
-    pub info_hash: [u8; 20],
-    pub piece_length: u64,
-    pub pieces: Vec<[u8; 20]>,
+    pub info_hash: Hash,
+    pub piece_length: u32,
+    pub num_pieces: u32,
+    pub pieces: Vec<Hash>,
+    pub length: u64,
 }
 
 impl Metainfo {
@@ -34,6 +38,11 @@ impl Metainfo {
         let name = ts!(info.get_str("name"));
         let piece_length = ts!(info.get_int("piece length"));
         let pieces = ts!(info.get_bytes("pieces"));
+        let mut total_length = 0;
+
+        if pieces.len() % 20 != 0 {
+            return None;
+        }
 
         let mut announce_list = vec![];
         if let Some(list) = metainfo.get_list("announce-list") {
@@ -57,8 +66,11 @@ impl Metainfo {
                     path.push(ts!(component.as_str()));
                 }
 
+                let length = ts!(file.get_int("length")) as u64;
+                total_length += length;
+
                 files.push(MetainfoFile {
-                    length: ts!(file.get_int("length")) as u64,
+                    length: length,
                     path: path,
                 });
             }
@@ -66,19 +78,25 @@ impl Metainfo {
             let mut path = PathBuf::new();
             path.push(name);
 
+            total_length = ts!(info.get_int("length")) as u64;
+
             files.push(MetainfoFile{
-                length: ts!(info.get_int("length")) as u64,
+                length: total_length,
                 path: path,
             })
         }
 
+        let pieces = pieces.chunks(20).map(Hash::from_slice).collect::<Vec<_>>();
+
         Some(Metainfo {
             announce: announce,
             announce_list: announce_list,
             files: files,
             info_hash: info_hash,
-            piece_length: piece_length as u64,
-            pieces: pieces.chunks(20).map(|c| piece_from_slice(c)).collect::<Vec<_>>(),
+            piece_length: piece_length as u32,
+            num_pieces: pieces.len() as u32,
+            pieces: pieces,
+            length: total_length,
         })
     }
 }
@@ -89,18 +107,54 @@ pub struct MetainfoFile {
     pub path: PathBuf,
 }
 
-fn sha1(bytes: &[u8]) -> [u8; 20] {
+fn sha1(bytes: &[u8]) -> Hash {
     let mut hasher = Sha1::new();
     hasher.update(bytes);
-    hasher.digest().bytes()
+    Hash::new(hasher.digest().bytes())
 }
 
-fn piece_from_slice(src: &[u8]) -> [u8; 20] {
-    assert_eq!(src.len(), 20);
 
-    let mut dst = [0u8; 20];
-    dst.copy_from_slice(src);
-    dst
+#[derive(Clone, Copy, Eq, Hash, PartialEq)]
+pub struct Hash([u8; 20]);
+
+impl Hash {
+    pub fn alloc() -> Hash {
+        Hash([0u8; 20])
+    }
+
+    pub fn new(inner: [u8; 20]) -> Hash {
+        Hash(inner)
+    }
+
+    pub fn from_slice(bytes: &[u8]) -> Hash {
+        assert_eq!(bytes.len(), 20);
+        let mut hash = Hash::alloc();
+        hash.copy_from_slice(bytes);
+        hash
+    }
+}
+
+impl fmt::Debug for Hash {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        for &b in self.0.iter() {
+            write!(f, "{:x}", b)?
+        }
+        Ok(())
+    }
+}
+
+impl Deref for Hash {
+    type Target = [u8];
+
+    fn deref(&self) -> &[u8] {
+        &self.0
+    }
+}
+
+impl DerefMut for Hash {
+    fn deref_mut(&mut self) -> &mut [u8] {
+        &mut self.0
+    }
 }
 
 #[cfg(test)]
diff --git a/src/net/bitfield.rs b/src/net/bitfield.rs
new file mode 100644
index 0000000..24a6b6b
--- /dev/null
+++ b/src/net/bitfield.rs
@@ -0,0 +1,109 @@
+use std::fmt;
+
+pub struct BitField {
+    bits: Vec<u8>,
+    len: u32,
+}
+
+impl BitField {
+    pub fn new(bits: Vec<u8>, len: u32) -> BitField {
+        BitField {
+            bits: bits,
+            len: len,
+        }
+    }
+
+    pub fn with_capacity(len: u32) -> BitField {
+        BitField {
+            bits: vec![0u8; f64::ceil(len as f64 / 8.) as usize],
+            len: len,
+        }
+    }
+
+    #[inline]
+    pub fn len(&self) -> u32 {
+        self.len
+    }
+
+    #[inline]
+    pub fn is_set(&self, index: u32) -> bool {
+        let idx = index / 8;
+        let offset = index % 8;
+        (self.bits[idx as usize] & (1 << 7 - offset)) != 0
+    }
+
+    #[inline]
+    pub fn set(&mut self, index: u32) {
+        let idx = index / 8;
+        let offset = index % 8;
+        self.bits[idx as usize] |= 1 << 7 - offset;
+    }
+
+    #[inline]
+    pub fn unset(&mut self, index: u32) {
+        let idx = index / 8;
+        let offset = index % 8;
+        self.bits[idx as usize] ^= 1 << 7 - offset;
+    }
+
+    pub fn as_bytes(&self) -> &[u8] {
+        &self.bits
+    }
+}
+
+impl fmt::Debug for BitField {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "BitField {{ size: {} }}", self.bits.len() * 8)
+    }
+}
+
+#[test]
+fn test_bitfield_is_set() {
+    // 01234567 89abcdef
+    // 00111110 01111111
+    let bf = BitField::new(vec![62, 127]);
+
+    assert!(!bf.is_set(0));
+    assert!(!bf.is_set(1));
+    assert!(bf.is_set(2));
+    assert!(bf.is_set(3));
+    assert!(bf.is_set(4));
+    assert!(bf.is_set(5));
+    assert!(bf.is_set(6));
+    assert!(!bf.is_set(7));
+
+    assert!(!bf.is_set(8));
+    assert!(bf.is_set(9));
+    assert!(bf.is_set(0xa));
+    assert!(bf.is_set(0xb));
+    assert!(bf.is_set(0xc));
+    assert!(bf.is_set(0xd));
+    assert!(bf.is_set(0xe));
+    assert!(bf.is_set(0xf));
+}
+
+#[test]
+fn test_bitfield_set() {
+    let mut bf = BitField::new(vec![0, 0]);
+    bf.set(0);
+    assert_eq!(bf.bits[0], 128);
+    bf.set(7);
+    assert_eq!(bf.bits[0], 129);
+    bf.set(8);
+    assert_eq!(bf.bits[1], 128);
+    bf.set(15);
+    assert_eq!(bf.bits[1], 129);
+}
+
+#[test]
+fn test_bitfield_unset() {
+    let mut bf = BitField::new(vec![255, 255]);
+    bf.unset(0);
+    assert_eq!(bf.bits[0], 255-128);
+    bf.unset(7);
+    assert_eq!(bf.bits[0], 255-128-1);
+    bf.unset(8);
+    assert_eq!(bf.bits[1], 255-128);
+    bf.unset(15);
+    assert_eq!(bf.bits[1], 255-128-1);
+}
diff --git a/src/net/mod.rs b/src/net/mod.rs
new file mode 100644
index 0000000..0eadd19
--- /dev/null
+++ b/src/net/mod.rs
@@ -0,0 +1,3 @@
+pub mod bitfield;
+pub mod peer;
+pub mod session;
diff --git a/src/net/peer.rs b/src/net/peer.rs
new file mode 100644
index 0000000..be4e609
--- /dev/null
+++ b/src/net/peer.rs
@@ -0,0 +1,164 @@
+use std::io::{self, Read, Write};
+use std::net::TcpStream;
+
+use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
+
+use metainfo::Hash;
+use net::bitfield::BitField;
+use tracker::Peer;
+
+#[derive(Debug)]
+pub enum Packet {
+    Choke,
+    Unchoke,
+    Interested,
+    NotInterested,
+    Have {
+        index: u32,
+    },
+    Bitfield { bitfield: Vec<u8>, },
+    Request { index: u32, begin: u32, length: u32, },
+    Piece { index: u32, begin: u32, block: Vec<u8>, },
+    Cancel { index: u32, begin: u32, length: u32, }
+}
+
+pub fn open_connection(peer: Peer, own_info_hash: Hash, own_peer_id: Hash) -> io::Result<(TcpStream, TcpStream, Hash)> {
+    let mut sock = TcpStream::connect((peer.addr, peer.port))?;
+
+    // send handshake
+    sock.write_u8(19)?;
+    sock.write(b"BitTorrent protocol")?;
+    sock.write_u64::<BigEndian>(0)?;
+    sock.write(&own_info_hash)?;
+    sock.write(&own_peer_id)?;
+    sock.flush()?;
+
+    // receive handshake
+    let mut buf = [0u8; 68];
+    sock.read_exact(&mut buf)?;
+
+    let peer_info_hash = Hash::from_slice(&buf[28..48]);
+    let peer_id = Hash::from_slice(&buf[48..68]);
+
+    if buf[0] != 19 || &buf[1..20] != b"BitTorrent protocol" || own_info_hash != peer_info_hash {
+        return Err(io::Error::new(io::ErrorKind::Other, "invalid protocol"))
+    }
+
+    Ok((sock.try_clone()?, sock, peer_id))
+}
+
+pub fn read_packet(sock: &mut TcpStream) -> io::Result<Packet> {
+    let len = sock.read_u32::<BigEndian>()?;
+    let id = sock.read_u8()?;
+
+    Ok(match id {
+        0 => Packet::Choke,
+        1 => Packet::Unchoke,
+        2 => Packet::Interested,
+        3 => Packet::NotInterested,
+        4 => Packet::Have {
+            index: sock.read_u32::<BigEndian>()?,
+        },
+        5 => {
+            let size = len as usize - 1;
+            let mut bitfield = Vec::with_capacity(size);
+            unsafe {
+                bitfield.set_len(size);
+            }
+            sock.read_exact(&mut bitfield)?;
+            Packet::Bitfield {
+                bitfield: bitfield,
+            }
+        }
+        6 => Packet::Request {
+            index: sock.read_u32::<BigEndian>()?,
+            begin: sock.read_u32::<BigEndian>()?,
+            length: sock.read_u32::<BigEndian>()?,
+        },
+        7 => {
+            let size = len as usize - 9;
+            let index = sock.read_u32::<BigEndian>()?;
+            let begin = sock.read_u32::<BigEndian>()?;
+            let mut block = Vec::with_capacity(size);
+            unsafe {
+                block.set_len(size);
+            }
+            sock.read_exact(&mut block)?;
+
+            Packet::Piece {
+                index: index,
+                begin: begin,
+                block: block,
+            }
+        }
+        8 => Packet::Cancel {
+            index: sock.read_u32::<BigEndian>()?,
+            begin: sock.read_u32::<BigEndian>()?,
+            length: sock.read_u32::<BigEndian>()?,
+        },
+        _ => return Err(io::Error::new(io::ErrorKind::Other, "invalid packet")),
+    })
+}
+
+pub fn send_keepalive(sock: &mut TcpStream) -> io::Result<()> {
+    sock.write(b"")?;
+    Ok(())
+}
+
+pub fn send_choke(sock: &mut TcpStream) -> io::Result<()> {
+    sock.write_u32::<BigEndian>(1)?;
+    sock.write_u8(0)?;
+    Ok(())
+}
+
+pub fn send_unchoke(sock: &mut TcpStream) -> io::Result<()> {
+    sock.write_u32::<BigEndian>(1)?;
+    sock.write_u8(1)?;
+    Ok(())
+}
+
+pub fn send_interested(sock: &mut TcpStream) -> io::Result<()> {
+    sock.write_u32::<BigEndian>(1)?;
+    sock.write_u8(2)?;
+    Ok(())
+}
+
+pub fn send_not_interested(sock: &mut TcpStream) -> io::Result<()> {
+    sock.write_u32::<BigEndian>(1)?;
+    sock.write_u8(3)?;
+    Ok(())
+}
+
+pub fn send_have(sock: &mut TcpStream, piece: u32) -> io::Result<()> {
+    sock.write_u32::<BigEndian>(5)?;
+    sock.write_u8(4)?;
+    sock.write_u32::<BigEndian>(piece)?;
+    Ok(())
+}
+
+pub fn send_request(sock: &mut TcpStream, piece: u32, begin: u32, length: u32) -> io::Result<()> {
+    sock.write_u32::<BigEndian>(13)?;
+    sock.write_u8(6)?;
+    sock.write_u32::<BigEndian>(piece)?;
+    sock.write_u32::<BigEndian>(begin)?;
+    sock.write_u32::<BigEndian>(length)?;
+    Ok(())
+}
+
+pub fn send_piece(sock: &mut TcpStream, piece: u32, begin: u32, data: &[u8]) -> io::Result<()> {
+    sock.write_u32::<BigEndian>(9 + data.len() as u32)?;
+    sock.write_u8(7)?;
+    sock.write_u32::<BigEndian>(piece)?;
+    sock.write_u32::<BigEndian>(begin)?;
+    sock.write(data)?;
+    Ok(())
+}
+
+pub fn send_cancel(sock: &mut TcpStream, piece: u32, begin: u32, length: u32) -> io::Result<()> {
+    sock.write_u32::<BigEndian>(13)?;
+    sock.write_u8(8)?;
+    sock.write_u32::<BigEndian>(piece)?;
+    sock.write_u32::<BigEndian>(begin)?;
+    sock.write_u32::<BigEndian>(length)?;
+    Ok(())
+}
diff --git a/src/net/session.rs b/src/net/session.rs
new file mode 100644
index 0000000..3f7e80f
--- /dev/null
+++ b/src/net/session.rs
@@ -0,0 +1,450 @@
+use std::cmp;
+use std::collections::{BTreeMap, HashMap};
+use std::fs::File;
+use std::io::{Seek, SeekFrom, Write};
+use std::net::{Shutdown, TcpStream};
+use std::os::unix::io::AsRawFd;
+use std::sync::Arc;
+use std::sync::mpsc::{self, Receiver, Sender};
+use std::thread;
+use std::time::{Duration, Instant};
+
+use libc;
+use sha1::Sha1;
+
+use metainfo::{Hash, Metainfo};
+use net::bitfield::BitField;
+use net::peer::{self, Packet};
+use tracker::http;
+
+const FRAGMENT_SIZE: u32 = 16 * 1024;
+
+#[derive(Debug)]
+enum Signal {
+    // == Torrent ==
+    AddTorrent(Metainfo),
+    RemoveTorrent(Hash),
+    //ResumeTorrent(Hash),
+    //StopTorrent(Hash),
+    // == Peer ==
+    ConnectionOpened {
+        info_hash: Hash,
+        peer_id: Hash,
+        sock: TcpStream,
+    },
+    ConnectionClosed {
+        info_hash: Hash,
+        peer_id: Hash,
+    },
+    Packet {
+        info_hash: Hash,
+        peer_id: Hash,
+        packet: Packet,
+    },
+    // == Other ==
+    Stop,
+}
+
+struct InnerSession {
+    peer_id: Hash,
+    port: u16,
+}
+
+pub struct Session {
+    // inner: Arc<InnerSession>,
+    sender: Sender<Signal>,
+}
+
+impl Session {
+    pub fn new() -> Session {
+        let (sender, receiver) = mpsc::channel();
+
+        let inner = Arc::new(InnerSession {
+            peer_id: Hash::new([2u8; 20]),
+            port: 6981,
+        });
+
+        let thread = SessionNetworkThread {
+            session: inner.clone(),
+            sender: sender.clone(),
+            torrents: HashMap::new(),
+            seeds: 0,
+            bytecount: 0,
+            lastcount: Instant::now(),
+        };
+
+        thread::spawn(move || {
+            thread.run(receiver);
+        });
+
+        Session {
+            // inner: inner,
+            sender: sender,
+        }
+    }
+
+    pub fn add_torrent(&self, metainfo: Metainfo) {
+        let _ = self.sender.send(Signal::AddTorrent(metainfo));
+    }
+
+    pub fn remove_torrent(&self, id: Hash) {
+        let _ = self.sender.send(Signal::RemoveTorrent(id));
+    }
+
+    pub fn stop(&self) {
+        let _ = self.sender.send(Signal::Stop);
+    }
+}
+
+struct PeerConnection {
+    sock: TcpStream,
+    bitfield: BitField,
+    am_choking: bool,
+    am_interested: bool,
+    peer_choking: bool,
+    peer_interested: bool,
+}
+
+impl PeerConnection {
+    pub fn new(sock: TcpStream, bitfield_len: u32) -> Self {
+        PeerConnection {
+            sock: sock,
+            bitfield: BitField::with_capacity(bitfield_len),
+            am_choking: true,
+            am_interested: false,
+            peer_choking: true,
+            peer_interested: false,
+        }
+    }
+}
+
+#[derive(Copy, Clone, Debug)]
+enum FragmentStatus {
+    Available,
+    Complete,
+    Taken(Instant),
+}
+
+pub struct SessionFragment {
+    begin: u32,
+    length: u32,
+    status: FragmentStatus,
+}
+
+struct SessionPiece {
+    fragments: BTreeMap<u32, SessionFragment>,
+    buffer: Vec<u8>,
+    num_fragments: u32,
+    total_fragments: u32,
+}
+
+struct SessionTorrent {
+    metainfo: Metainfo,
+    own_bitfield: BitField,
+    peers: HashMap<Hash, PeerConnection>,
+    pieces: BTreeMap<u32, SessionPiece>,
+    files: Vec<File>,
+}
+
+impl SessionTorrent {
+    pub fn new(metainfo: Metainfo, files: Vec<File>) -> Self {
+        SessionTorrent {
+            own_bitfield: BitField::with_capacity(metainfo.pieces.len() as u32),
+            metainfo: metainfo,
+            peers: HashMap::new(),
+            pieces: BTreeMap::new(),
+            files: files,
+        }
+    }
+
+    pub fn get_peer(&mut self, peer_id: &Hash) -> &mut PeerConnection {
+        self.peers.get_mut(peer_id).unwrap()
+    }
+
+    // Get the requesting connection something to download. Check in the pieces currently
+    // in flight, match with the peer's bitfield, and if nothing matches, fly a new piece.
+    // (scheduler)
+    pub fn get_fragment(&mut self, peer_id: &Hash) -> Option<(u32, u32, u32)> {
+        let peer = &self.peers[peer_id];
+
+        // try to find a fragment from the pieces in flight
+        for (&index, piece) in self.pieces.iter_mut() {
+            if peer.bitfield.is_set(index) {
+                for fragment in piece.fragments.values_mut() {
+                    match fragment.status {
+                        FragmentStatus::Available => {
+                            fragment.status = FragmentStatus::Taken(Instant::now());
+                            return Some((index, fragment.begin, fragment.length))
+                        }
+                        FragmentStatus::Complete => continue,
+                        FragmentStatus::Taken(timestamp) => {
+                            if timestamp.elapsed() > Duration::from_secs(10) {
+                                println!("retrying fragment");
+                                fragment.status = FragmentStatus::Taken(Instant::now());
+                                return Some((index, fragment.begin, fragment.length))
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        // Collect the list of pieces currently in flight, to avoid re-fragmenting the same piece over and over.
+        let keys: Vec<_> = self.pieces.keys().cloned().collect();
+
+        println!("fragmenting a new piece, in flight = {:?}", keys);
+
+        // TODO: optimize currently O(n). It's also ugly as hell
+        for index in (0..self.own_bitfield.len()).filter(|index| !keys.contains(index)) {
+            if !self.own_bitfield.is_set(index) && peer.bitfield.is_set(index) {
+
+                let total_fragments = f64::ceil(self.metainfo.piece_length as f64 / FRAGMENT_SIZE as f64) as u32;
+                let mut fragments = BTreeMap::new();
+                for idx in 0..total_fragments {
+                    let begin = idx * FRAGMENT_SIZE;
+
+                    fragments.insert(begin ,SessionFragment {
+                        begin: begin,
+                        length: cmp::min(FRAGMENT_SIZE, self.metainfo.piece_length - (idx * FRAGMENT_SIZE)),
+                        status: FragmentStatus::Available,
+                    });
+                }
+
+                let begin;
+                let length;
+                {
+                    let taken = fragments.get_mut(&0).unwrap();
+                    taken.status = FragmentStatus::Taken(Instant::now());
+                    begin = taken.begin;
+                    length = taken.length;
+                }
+
+                let mut buffer = Vec::with_capacity(self.metainfo.piece_length as usize);
+                unsafe {
+                    buffer.set_len(self.metainfo.piece_length as usize);
+                }
+                self.pieces.insert(index, SessionPiece {
+                    fragments: fragments,
+                    buffer: buffer,
+                    num_fragments: 0,
+                    total_fragments: total_fragments,
+                });
+
+                return Some((index, begin, length));
+            }
+        }
+
+        None
+    }
+
+    fn requeue(&mut self, peer_id: &Hash) {
+        if let Some((index, begin, length)) = self.get_fragment(peer_id) {
+            // println!("onto piece {} {}..{}", index, begin, begin + length);
+            peer::send_request(&mut self.get_peer(&peer_id).sock, index, begin,length);
+        } else {
+            println!("no fragment");
+        }
+    }
+
+    fn write_piece(&mut self, index: u32) {
+        let mut start = 0;
+        let mut end = 0;
+        let mut pos: u64 = 0;
+        let mut remaining = self.metainfo.piece_length as u64;
+        let mut write = index as u64 * self.metainfo.piece_length as u64;
+
+        for (id, fileinfo) in self.metainfo.files.iter().enumerate() {
+            end += fileinfo.length as u64;
+            println!("in file {}, start={}, end={}, pos={}, remaining={}, write={}", fileinfo.path.display(), start, end, pos, remaining, write);
+            if write < end {
+                let len = cmp::min(remaining, fileinfo.length as u64);
+                self.files[id].seek(SeekFrom::Start(write - start));
+                self.files[id].write_all(&self.pieces[&index].buffer[pos as usize..(pos+len) as usize]);
+                write += len;
+                pos += len;
+                remaining -= len;
+                if remaining == 0 {
+                    break;
+                }
+            }
+            start = end;
+        }
+    }
+
+    fn unchoke_reply(&mut self, peer_id: &Hash) {
+        self.get_peer(&peer_id).peer_choking = false;
+        self.requeue(peer_id);
+    }
+
+    fn piece_reply(&mut self, peer_id: &Hash, index: u32, begin: u32, block: Vec<u8>) {
+        let mut remove = false;
+        {
+            if let Some(piece) = self.pieces.get_mut(&index) {
+                if let Some(fragment) = piece.fragments.get_mut(&begin) {
+                    fragment.status = FragmentStatus::Complete;
+
+                    piece.buffer[begin as usize..(begin as usize)+block.len()].copy_from_slice(&block);
+                    piece.num_fragments += 1;
+                    if piece.num_fragments == piece.total_fragments {
+                        // TODO check hash
+                        println!("piece is done {}", index);
+                        let mut m = Sha1::new();
+                        m.update(&piece.buffer);
+                        if m.digest().bytes() == &self.metainfo.pieces[index as usize][..] {
+                            self.own_bitfield.set(index);
+                            println!("it's a match!");
+                            remove = true;
+                        } else {
+                            println!("no match");
+                        }
+                    }
+                } else {
+                    println!("could not find fragment {}", begin);
+                }
+            } else {
+                println!("could not find piece {}", index);
+            }
+        }
+        if remove {
+            self.write_piece(index);
+            self.pieces.remove(&index);
+        }
+        self.requeue(peer_id);
+    }
+}
+
+struct SessionNetworkThread {
+    session: Arc<InnerSession>,
+    sender: Sender<Signal>,
+    torrents: HashMap<Hash, SessionTorrent>,
+    seeds: u32,
+    bytecount: u64,
+    lastcount: Instant,
+}
+
+impl SessionNetworkThread {
+    pub fn run(mut self, input: Receiver<Signal>) {
+        for signal in input.iter() {
+            match signal {
+                Signal::AddTorrent(torrent) => self.signal_add_torrent(torrent),
+                Signal::RemoveTorrent(id) => {
+                    if let Some(mut sess_torrent) = self.torrents.remove(&id) {
+                        for conn in sess_torrent.peers.values_mut() {
+                            let _ = conn.sock.shutdown(Shutdown::Both);
+                        }
+                    }
+                }
+                Signal::ConnectionOpened { info_hash, peer_id, sock } => {
+                    if let Some(sess_torrent) = self.torrents.get_mut(&info_hash) {
+                        let mut peer = PeerConnection::new(sock, sess_torrent.metainfo.pieces.len() as u32);
+                        peer::send_interested(&mut peer.sock);
+                        peer.am_interested = true;
+                        sess_torrent.peers.insert(peer_id, peer);
+                    }
+                }
+                Signal::ConnectionClosed { info_hash, peer_id } => {
+                    if let Some(sess_torrent) = self.torrents.get_mut(&info_hash) {
+                        if let Some(mut peer) = sess_torrent.peers.remove(&peer_id) {
+                            // if !peer.peer_choking && self.seeds > 1 {
+                            //     self.seeds -= 1;
+                            // }
+                        }
+                    }
+                }
+                Signal::Packet { info_hash, peer_id, packet } => self.signal_packet(info_hash, peer_id, packet),
+                Signal::Stop => break,
+            }
+        }
+    }
+
+    fn signal_add_torrent(&mut self, metainfo: Metainfo) {
+        let own_peer_id = self.session.peer_id;
+        let info_hash = metainfo.info_hash;
+
+        let mut files = Vec::new();
+        for fileinfo in metainfo.files.iter() {
+            let file = File::create(&fileinfo.path).unwrap();
+            unsafe {
+                libc::ftruncate64(file.as_raw_fd(), fileinfo.length as i64);
+            }
+            files.push(file);
+        }
+
+        if let Ok(resp) = http::get_peers(own_peer_id, self.session.port, &metainfo, 0, 0, 0) {
+            self.torrents.insert(info_hash, SessionTorrent::new(metainfo, files));
+
+            println!("trying with {} peers", resp.peers.len());
+
+            for &peer in resp.peers.iter() {
+                let sender = self.sender.clone();
+
+                thread::spawn(move || {
+                    if let Ok((mut sock, sock_clone, peer_id)) = peer::open_connection(peer, info_hash, own_peer_id) {
+                        let _ = sender.send(Signal::ConnectionOpened {
+                            info_hash: info_hash,
+                            peer_id: peer_id,
+                            sock: sock_clone,
+                        });
+
+                        while let Ok(packet) = peer::read_packet(&mut sock) {
+                            let _ = sender.send(Signal::Packet {
+                                info_hash: info_hash,
+                                peer_id: peer_id,
+                                packet: packet,
+                            });
+                        }
+
+                        let _ = sender.send(Signal::ConnectionClosed {
+                            info_hash: info_hash,
+                            peer_id: peer_id,
+                        });
+                    }
+                });
+            }
+        }
+    }
+
+    fn signal_packet(&mut self, info_hash: Hash, peer_id: Hash, packet: Packet) {
+        if let Some(torrent) = self.torrents.get_mut(&info_hash) {
+            match packet {
+                Packet::Choke => {
+                    torrent.get_peer(&peer_id).peer_choking = true;
+                }
+                Packet::Unchoke => {
+                    self.seeds += 1;
+                    println!("seeds {}", self.seeds);
+                    torrent.unchoke_reply(&peer_id);
+                }
+                Packet::Interested => {
+                    torrent.get_peer(&peer_id).peer_interested = true;
+                }
+                Packet::NotInterested => {
+                    torrent.get_peer(&peer_id).peer_interested = false;
+                }
+                Packet::Have { index } => {
+                    if index < torrent.metainfo.num_pieces {
+                        torrent.get_peer(&peer_id).bitfield.set(index);
+                    }
+                }
+                Packet::Bitfield { bitfield } => {
+                    torrent.get_peer(&peer_id).bitfield = BitField::new(bitfield, torrent.metainfo.pieces.len() as u32);
+                }
+                Packet::Request { index, begin, length } => {
+                    // TODO
+                }
+                Packet::Piece { index, begin, block } => {
+                    self.bytecount += block.len() as u64;
+                    if self.lastcount.elapsed() >= Duration::from_secs(1) {
+                        println!("{:.2} KiB/s", self.bytecount as f64 / 1024.);
+                        self.bytecount = 0;
+                        self.lastcount = Instant::now();
+                    }
+                    torrent.piece_reply(&peer_id, index, begin, block);
+                }
+                Packet::Cancel { index, begin, length } => {
+                    // TODO
+                }
+            }
+        }
+    }
+}
diff --git a/src/torrent.rs b/src/torrent.rs
deleted file mode 100644
index 87171e9..0000000
--- a/src/torrent.rs
+++ /dev/null
@@ -1,8 +0,0 @@
-use metainfo::Metainfo;
-
-pub struct Torrent {
-    pub metainfo: Metainfo,
-    pub downloaded: u64,
-    pub uploaded: u64,
-    pub left: u64,
-}
diff --git a/src/tracker/http.rs b/src/tracker/http.rs
index e5de564..cc39f4f 100644
--- a/src/tracker/http.rs
+++ b/src/tracker/http.rs
@@ -5,7 +5,7 @@ use hyper::Client;
 use url::form_urlencoded::byte_serialize;
 
 use bencode::{decode, Dict};
-use torrent::Torrent;
+use metainfo::{Hash, Metainfo};
 use tracker::{Peer, TrackerError, TrackerResponse, TrackerResult};
 
 macro_rules! ts {
@@ -17,16 +17,16 @@ macro_rules! ts {
     }
 }
 
-pub fn get_peers(peer_id: [u8; 20], port: u16, torrent: &Torrent) -> TrackerResult {
+pub fn get_peers(peer_id: Hash, port: u16, metainfo: &Metainfo, uploaded: u64, downloaded: u64, left: u64) -> TrackerResult {
     let url = format!("{}?info_hash={}&peer_id={}&port={}&uploaded={}\
                        &downloaded={}&left={}&compact=1",
-                      torrent.metainfo.announce,
-                      urlencode(&torrent.metainfo.info_hash),
+                      metainfo.announce,
+                      urlencode(&metainfo.info_hash),
                       urlencode(&peer_id),
                       port,
-                      torrent.uploaded,
-                      torrent.downloaded,
-                      torrent.left);
+                      uploaded,
+                      downloaded,
+                      left);
 
     let client = Client::new();
     let mut resp = client.get(&url).send()?;
diff --git a/src/tracker/mod.rs b/src/tracker/mod.rs
index 3cd433b..17d9a0e 100644
--- a/src/tracker/mod.rs
+++ b/src/tracker/mod.rs
@@ -41,7 +41,7 @@ impl From<DecodeError> for TrackerError {
     }
 }
 
-#[derive(Debug)]
+#[derive(Copy, Clone, Debug)]
 pub struct Peer {
     pub addr: Ipv4Addr,
     pub port: u16,