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socket.go
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socket.go
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// Copyright (c) 2012-2014 Jeremy Latt
// Copyright (c) 2016-2017 Daniel Oaks <daniel@danieloaks.net>
// released under the MIT license
package irc
import (
"bufio"
"crypto/sha256"
"crypto/tls"
"encoding/hex"
"errors"
"io"
"net"
"strings"
"sync"
"time"
)
var (
handshakeTimeout, _ = time.ParseDuration("5s")
errSendQExceeded = errors.New("SendQ exceeded")
)
// Socket represents an IRC socket.
type Socket struct {
sync.Mutex
conn net.Conn
reader *bufio.Reader
maxSendQBytes int
// coordination system for asynchronous writes
buffer []byte
lineToSendExists chan bool
closed bool
sendQExceeded bool
finalData string // what to send when we die
}
// NewSocket returns a new Socket.
func NewSocket(conn net.Conn, maxReadQBytes int, maxSendQBytes int) Socket {
return Socket{
conn: conn,
reader: bufio.NewReaderSize(conn, maxReadQBytes),
maxSendQBytes: maxSendQBytes,
lineToSendExists: make(chan bool, 1),
}
}
// Close stops a Socket from being able to send/receive any more data.
func (socket *Socket) Close() {
socket.Lock()
socket.closed = true
socket.Unlock()
socket.wakeWriter()
}
// CertFP returns the fingerprint of the certificate provided by the client.
func (socket *Socket) CertFP() (string, error) {
var tlsConn, isTLS = socket.conn.(*tls.Conn)
if !isTLS {
return "", errNotTLS
}
// ensure handehake is performed, and timeout after a few seconds
tlsConn.SetDeadline(time.Now().Add(handshakeTimeout))
err := tlsConn.Handshake()
tlsConn.SetDeadline(time.Time{})
if err != nil {
return "", err
}
peerCerts := tlsConn.ConnectionState().PeerCertificates
if len(peerCerts) < 1 {
return "", errNoPeerCerts
}
rawCert := sha256.Sum256(peerCerts[0].Raw)
fingerprint := hex.EncodeToString(rawCert[:])
return fingerprint, nil
}
// Read returns a single IRC line from a Socket.
func (socket *Socket) Read() (string, error) {
if socket.IsClosed() {
return "", io.EOF
}
lineBytes, isPrefix, err := socket.reader.ReadLine()
if isPrefix {
return "", errReadQ
}
// convert bytes to string
line := string(lineBytes)
// read last message properly (such as ERROR/QUIT/etc), just fail next reads/writes
if err == io.EOF {
socket.Close()
}
if err == io.EOF && strings.TrimSpace(line) != "" {
// don't do anything
} else if err != nil {
return "", err
}
return line, nil
}
// Write sends the given string out of Socket.
func (socket *Socket) Write(data string) (err error) {
socket.Lock()
if socket.closed {
err = io.EOF
} else if len(data)+len(socket.buffer) > socket.maxSendQBytes {
socket.sendQExceeded = true
err = errSendQExceeded
} else {
socket.buffer = append(socket.buffer, data...)
}
socket.Unlock()
socket.wakeWriter()
return
}
// wakeWriter wakes up the goroutine that actually performs the write, without blocking
func (socket *Socket) wakeWriter() {
// nonblocking send to the channel, no-op if it's full
select {
case socket.lineToSendExists <- true:
default:
}
}
// SetFinalData sets the final data to send when the SocketWriter closes.
func (socket *Socket) SetFinalData(data string) {
socket.Lock()
defer socket.Unlock()
socket.finalData = data
}
// IsClosed returns whether the socket is closed.
func (socket *Socket) IsClosed() bool {
socket.Lock()
defer socket.Unlock()
return socket.closed
}
// RunSocketWriter starts writing messages to the outgoing socket.
func (socket *Socket) RunSocketWriter() {
localBuffer := make([]byte, 0)
shouldStop := false
for !shouldStop {
// wait for new lines
select {
case <-socket.lineToSendExists:
// retrieve the buffered data, clear the buffer
socket.Lock()
localBuffer = append(localBuffer, socket.buffer...)
socket.buffer = socket.buffer[:0]
socket.Unlock()
_, err := socket.conn.Write(localBuffer)
localBuffer = localBuffer[:0]
socket.Lock()
shouldStop = (err != nil) || socket.closed || socket.sendQExceeded
socket.Unlock()
}
}
// mark the socket closed (if someone hasn't already), then write error lines
socket.Lock()
socket.closed = true
finalData := socket.finalData
if socket.sendQExceeded {
finalData = "\r\nERROR :SendQ Exceeded\r\n"
}
socket.Unlock()
if finalData != "" {
socket.conn.Write([]byte(finalData))
}
// close the connection
socket.conn.Close()
}