mirror of
https://github.com/cwinfo/yggdrasil-go.git
synced 2024-11-15 14:20:29 +00:00
444 lines
13 KiB
Go
444 lines
13 KiB
Go
package yggdrasil
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// This sends packets to peers using TCP as a transport
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// It's generally better tested than the UDP implementation
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// Using it regularly is insane, but I find TCP easier to test/debug with it
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// Updating and optimizing the UDP version is a higher priority
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// TODO:
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// Something needs to make sure we're getting *valid* packets
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// Could be used to DoS (connect, give someone else's keys, spew garbage)
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// I guess the "peer" part should watch for link packets, disconnect?
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// TCP connections start with a metadata exchange.
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// It involves exchanging version numbers and crypto keys
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// See version.go for version metadata format
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import (
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"errors"
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"fmt"
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"io"
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"math/rand"
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"net"
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"sync"
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"sync/atomic"
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"time"
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"golang.org/x/net/proxy"
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)
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const tcp_msgSize = 2048 + 65535 // TODO figure out what makes sense
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const default_tcp_timeout = 6 * time.Second
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const tcp_ping_interval = (default_tcp_timeout * 2 / 3)
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// The TCP listener and information about active TCP connections, to avoid duplication.
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type tcpInterface struct {
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core *Core
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serv net.Listener
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tcp_timeout time.Duration
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mutex sync.Mutex // Protecting the below
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calls map[string]struct{}
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conns map[tcpInfo](chan struct{})
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}
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// This is used as the key to a map that tracks existing connections, to prevent multiple connections to the same keys and local/remote address pair from occuring.
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// Different address combinations are allowed, so multi-homing is still technically possible (but not necessarily advisable).
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type tcpInfo struct {
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box boxPubKey
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sig sigPubKey
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localAddr string
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remoteAddr string
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}
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// Wrapper function to set additional options for specific connection types.
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func (iface *tcpInterface) setExtraOptions(c net.Conn) {
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switch sock := c.(type) {
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case *net.TCPConn:
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sock.SetNoDelay(true)
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sock.SetKeepAlive(true)
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sock.SetKeepAlivePeriod(iface.tcp_timeout)
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panic("DEBUG testing")
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// TODO something for socks5
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default:
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iface.core.log.Println("Unrecognized connection type: %v", sock)
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}
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}
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// Returns the address of the listener.
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func (iface *tcpInterface) getAddr() *net.TCPAddr {
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return iface.serv.Addr().(*net.TCPAddr)
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}
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// Attempts to initiate a connection to the provided address.
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func (iface *tcpInterface) connect(addr string, intf string) {
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iface.call(addr, nil, intf)
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}
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// Attempst to initiate a connection to the provided address, viathe provided socks proxy address.
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func (iface *tcpInterface) connectSOCKS(socksaddr, peeraddr string) {
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iface.call(peeraddr, &socksaddr, "")
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}
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// Initializes the struct.
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func (iface *tcpInterface) init(core *Core, addr string, readTimeout int32) (err error) {
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iface.core = core
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iface.tcp_timeout = time.Duration(readTimeout) * time.Millisecond
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if iface.tcp_timeout >= 0 && iface.tcp_timeout < default_tcp_timeout {
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iface.tcp_timeout = default_tcp_timeout
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}
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iface.serv, err = net.Listen("tcp", addr)
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if err == nil {
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iface.calls = make(map[string]struct{})
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iface.conns = make(map[tcpInfo](chan struct{}))
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go iface.listener()
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}
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return err
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}
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// Runs the listener, which spawns off goroutines for incoming connections.
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func (iface *tcpInterface) listener() {
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defer iface.serv.Close()
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iface.core.log.Println("Listening for TCP on:", iface.serv.Addr().String())
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for {
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sock, err := iface.serv.Accept()
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if err != nil {
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panic(err)
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}
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go iface.handler(sock, true)
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}
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}
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// Checks if a connection already exists.
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// If not, it adds it to the list of active outgoing calls (to block future attempts) and dials the address.
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// If the dial is successful, it launches the handler.
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// When finished, it removes the outgoing call, so reconnection attempts can be made later.
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// This all happens in a separate goroutine that it spawns.
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func (iface *tcpInterface) call(saddr string, socksaddr *string, sintf string) {
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go func() {
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callname := saddr
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if sintf != "" {
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callname = fmt.Sprintf("%s/%s", saddr, sintf)
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}
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quit := false
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iface.mutex.Lock()
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if _, isIn := iface.calls[callname]; isIn {
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quit = true
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} else {
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iface.calls[callname] = struct{}{}
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defer func() {
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// Block new calls for a little while, to mitigate livelock scenarios
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time.Sleep(default_tcp_timeout)
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time.Sleep(time.Duration(rand.Intn(1000)) * time.Millisecond)
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iface.mutex.Lock()
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delete(iface.calls, callname)
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iface.mutex.Unlock()
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}()
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}
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iface.mutex.Unlock()
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if quit {
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return
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}
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var conn net.Conn
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var err error
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if socksaddr != nil {
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if sintf != "" {
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return
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}
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var dialer proxy.Dialer
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dialer, err = proxy.SOCKS5("tcp", *socksaddr, nil, proxy.Direct)
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if err != nil {
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return
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}
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conn, err = dialer.Dial("tcp", saddr)
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if err != nil {
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return
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}
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conn = &wrappedConn{
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c: conn,
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raddr: &wrappedAddr{
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network: "tcp",
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addr: saddr,
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},
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}
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} else {
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dialer := net.Dialer{}
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if sintf != "" {
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ief, err := net.InterfaceByName(sintf)
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if err != nil {
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return
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} else {
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if ief.Flags&net.FlagUp == 0 {
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return
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}
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addrs, err := ief.Addrs()
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if err == nil {
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dst, err := net.ResolveTCPAddr("tcp", saddr)
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if err != nil {
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return
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}
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for _, addr := range addrs {
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src, _, err := net.ParseCIDR(addr.String())
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if err != nil {
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continue
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}
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if (src.To4() != nil) == (dst.IP.To4() != nil) && src.IsGlobalUnicast() {
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dialer.LocalAddr = &net.TCPAddr{
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IP: src,
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Port: 0,
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}
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break
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}
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}
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if dialer.LocalAddr == nil {
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return
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}
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}
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}
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}
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conn, err = dialer.Dial("tcp", saddr)
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if err != nil {
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return
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}
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}
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iface.handler(conn, false)
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}()
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}
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// This exchanges/checks connection metadata, sets up the peer struct, sets up the writer goroutine, and then runs the reader within the current goroutine.
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// It defers a bunch of cleanup stuff to tear down all of these things when the reader exists (e.g. due to a closed connection or a timeout).
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func (iface *tcpInterface) handler(sock net.Conn, incoming bool) {
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defer sock.Close()
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iface.setExtraOptions(sock)
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// Get our keys
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myLinkPub, myLinkPriv := newBoxKeys() // ephemeral link keys
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meta := version_getBaseMetadata()
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meta.box = iface.core.boxPub
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meta.sig = iface.core.sigPub
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meta.link = *myLinkPub
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metaBytes := meta.encode()
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_, err := sock.Write(metaBytes)
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if err != nil {
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return
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}
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if iface.tcp_timeout > 0 {
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sock.SetReadDeadline(time.Now().Add(iface.tcp_timeout))
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}
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_, err = sock.Read(metaBytes)
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if err != nil {
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return
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}
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meta = version_metadata{} // Reset to zero value
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if !meta.decode(metaBytes) || !meta.check() {
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// Failed to decode and check the metadata
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// If it's a version mismatch issue, then print an error message
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base := version_getBaseMetadata()
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if meta.meta == base.meta {
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if meta.ver > base.ver {
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iface.core.log.Println("Failed to connect to node:", sock.RemoteAddr().String(), "version:", meta.ver)
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} else if meta.ver == base.ver && meta.minorVer > base.minorVer {
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iface.core.log.Println("Failed to connect to node:", sock.RemoteAddr().String(), "version:", fmt.Sprintf("%d.%d", meta.ver, meta.minorVer))
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}
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}
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// TODO? Block forever to prevent future connection attempts? suppress future messages about the same node?
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return
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}
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info := tcpInfo{ // used as a map key, so don't include ephemeral link key
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box: meta.box,
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sig: meta.sig,
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}
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// Quit the parent call if this is a connection to ourself
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equiv := func(k1, k2 []byte) bool {
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for idx := range k1 {
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if k1[idx] != k2[idx] {
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return false
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}
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}
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return true
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}
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if equiv(info.box[:], iface.core.boxPub[:]) {
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return
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}
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if equiv(info.sig[:], iface.core.sigPub[:]) {
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return
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}
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// Check if we're authorized to connect to this key / IP
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if incoming && !iface.core.peers.isAllowedEncryptionPublicKey(&info.box) {
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// Allow unauthorized peers if they're link-local
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raddrStr, _, _ := net.SplitHostPort(sock.RemoteAddr().String())
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raddr := net.ParseIP(raddrStr)
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if !raddr.IsLinkLocalUnicast() {
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return
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}
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}
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// Check if we already have a connection to this node, close and block if yes
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info.localAddr, _, _ = net.SplitHostPort(sock.LocalAddr().String())
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info.remoteAddr, _, _ = net.SplitHostPort(sock.RemoteAddr().String())
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iface.mutex.Lock()
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if blockChan, isIn := iface.conns[info]; isIn {
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iface.mutex.Unlock()
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sock.Close()
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<-blockChan
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return
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}
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blockChan := make(chan struct{})
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iface.conns[info] = blockChan
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iface.mutex.Unlock()
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defer func() {
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iface.mutex.Lock()
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delete(iface.conns, info)
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iface.mutex.Unlock()
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close(blockChan)
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}()
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// Note that multiple connections to the same node are allowed
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// E.g. over different interfaces
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p := iface.core.peers.newPeer(&info.box, &info.sig, getSharedKey(myLinkPriv, &meta.link), sock.RemoteAddr().String())
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p.linkOut = make(chan []byte, 1)
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in := func(bs []byte) {
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p.handlePacket(bs)
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}
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out := make(chan []byte, 1)
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defer close(out)
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go func() {
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// This goroutine waits for outgoing packets, link protocol traffic, or sends idle keep-alive traffic
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send := func(msg []byte) {
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msgLen := wire_encode_uint64(uint64(len(msg)))
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buf := net.Buffers{tcp_msg[:], msgLen, msg}
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buf.WriteTo(sock)
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atomic.AddUint64(&p.bytesSent, uint64(len(tcp_msg)+len(msgLen)+len(msg)))
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util_putBytes(msg)
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}
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timerInterval := tcp_ping_interval
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timer := time.NewTimer(timerInterval)
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defer timer.Stop()
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for {
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select {
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case msg := <-p.linkOut:
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// Always send outgoing link traffic first, if needed
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send(msg)
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continue
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default:
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}
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// Otherwise wait reset the timer and wait for something to do
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timer.Stop()
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select {
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case <-timer.C:
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default:
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}
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timer.Reset(timerInterval)
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select {
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case _ = <-timer.C:
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send(nil) // TCP keep-alive traffic
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case msg := <-p.linkOut:
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send(msg)
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case msg, ok := <-out:
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if !ok {
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return
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}
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send(msg) // Block until the socket write has finished
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// Now inform the switch that we're ready for more traffic
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p.core.switchTable.idleIn <- p.port
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}
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}
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}()
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p.core.switchTable.idleIn <- p.port // Start in the idle state
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p.out = func(msg []byte) {
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defer func() { recover() }()
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out <- msg
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}
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p.close = func() { sock.Close() }
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go p.linkLoop()
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defer func() {
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// Put all of our cleanup here...
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p.core.peers.removePeer(p.port)
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}()
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us, _, _ := net.SplitHostPort(sock.LocalAddr().String())
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them, _, _ := net.SplitHostPort(sock.RemoteAddr().String())
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themNodeID := getNodeID(&info.box)
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themAddr := address_addrForNodeID(themNodeID)
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themAddrString := net.IP(themAddr[:]).String()
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themString := fmt.Sprintf("%s@%s", themAddrString, them)
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iface.core.log.Println("Connected:", themString, "source", us)
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err = iface.reader(sock, in) // In this goroutine, because of defers
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if err == nil {
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iface.core.log.Println("Disconnected:", themString, "source", us)
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} else {
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iface.core.log.Println("Disconnected:", themString, "source", us, "with error:", err)
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}
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return
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}
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// This reads from the socket into a []byte buffer for incomping messages.
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// It copies completed messages out of the cache into a new slice, and passes them to the peer struct via the provided `in func([]byte)` argument.
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// Then it shifts the incomplete fragments of data forward so future reads won't overwrite it.
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func (iface *tcpInterface) reader(sock net.Conn, in func([]byte)) error {
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bs := make([]byte, 2*tcp_msgSize)
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frag := bs[:0]
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for {
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if iface.tcp_timeout > 0 {
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sock.SetReadDeadline(time.Now().Add(iface.tcp_timeout))
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}
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n, err := sock.Read(bs[len(frag):])
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if n > 0 {
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frag = bs[:len(frag)+n]
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for {
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msg, ok, err2 := tcp_chop_msg(&frag)
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if err2 != nil {
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return fmt.Errorf("Message error: %v", err2)
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}
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if !ok {
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// We didn't get the whole message yet
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break
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}
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newMsg := append(util_getBytes(), msg...)
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in(newMsg)
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util_yield()
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}
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frag = append(bs[:0], frag...)
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}
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if err != nil || n == 0 {
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if err != io.EOF {
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return err
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}
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return nil
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}
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}
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}
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////////////////////////////////////////////////////////////////////////////////
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// These are 4 bytes of padding used to catch if something went horribly wrong with the tcp connection.
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var tcp_msg = [...]byte{0xde, 0xad, 0xb1, 0x75} // "dead bits"
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// This takes a pointer to a slice as an argument.
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// It checks if there's a complete message and, if so, slices out those parts and returns the message, true, and nil.
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// If there's no error, but also no complete message, it returns nil, false, and nil.
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// If there's an error, it returns nil, false, and the error, which the reader then handles (currently, by returning from the reader, which causes the connection to close).
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func tcp_chop_msg(bs *[]byte) ([]byte, bool, error) {
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// Returns msg, ok, err
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if len(*bs) < len(tcp_msg) {
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return nil, false, nil
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}
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for idx := range tcp_msg {
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if (*bs)[idx] != tcp_msg[idx] {
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return nil, false, errors.New("Bad message!")
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}
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}
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msgLen, msgLenLen := wire_decode_uint64((*bs)[len(tcp_msg):])
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if msgLen > tcp_msgSize {
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return nil, false, errors.New("Oversized message!")
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}
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msgBegin := len(tcp_msg) + msgLenLen
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msgEnd := msgBegin + int(msgLen)
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if msgLenLen == 0 || len(*bs) < msgEnd {
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// We don't have the full message
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// Need to buffer this and wait for the rest to come in
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return nil, false, nil
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}
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msg := (*bs)[msgBegin:msgEnd]
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(*bs) = (*bs)[msgEnd:]
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return msg, true, nil
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}
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