// The main loop.
// * The main job is to pass messages between standard input/output, the OTR
// library, the TCP socket.
// * It starts goroutines that listen on standard input and the TCP socket.
// Note: it only starts listening on standard input when an encrypted
// connection has been established, to prevent any data being sent in plain
// text.
// * When an encrypted session has been established, it checks if the contact
// is authentication and authorised (according to -remember and -expect).
func mainLoop(privateKey otr.PrivateKey, upstream io.ReadWriter) {
var conv otr.Conversation
var theirFingerprint string = ""
conv.PrivateKey = &privateKey
netOutChan := make(chan []byte, 100)
netInChan := make(chan []byte, 100)
stdOutChan := make(chan []byte, 100)
stdInChan := make(chan []byte, 100)
sigTermChan := make(chan os.Signal)
// Delimit ciphertext messages with newlines
var nl = []byte("\n")
msgSender, msgReceiver := NewDelimitedSender(upstream, nl), NewDelimitedReceiver(upstream, nl)
go SendForever(msgSender, netOutChan)
go ReceiveForever(msgReceiver, netInChan)
// Don't touch secret input or output anything until we are sure everything
// is encrypted and authorised.
// go bufferedReadLoop(os.Stdin, stdInChan)
// go writeLoop(os.Stdout, stdOutChan)
go sigLoop(sigTermChan)
send := func(toSend [][]byte) {
for _, msg := range toSend {
netOutChan <- msg
}
}
stdInChan <- []byte(otr.QueryMessage) // Queue a handshake message to be sent
authorised := false // conversation ready to send secret data?
Loop:
for {
select {
case <-sigTermChan:
break Loop
case plaintext, alive := <-stdInChan:
// fmt.Fprintf(os.Stderr, "Read %d bytes of plaintext.\n", len(plaintext))
if !alive {
break Loop
}
if bytes.Index(plaintext, []byte{0}) != -1 {
fmt.Fprintf(os.Stderr,
"The OTR protocol only supports UTF8-encoded text.\n"+
"Please use base64 or another suitable encoding for binary data.\n")
break Loop
}
toSend, err := conv.Send(plaintext)
if err != nil {
exitError(err)
}
send(toSend)
case otrText, alive := <-netInChan:
if !alive {
if authorised {
exitPrintf("Connection dropped! Recent messages might not be deniable.\n")
}
exitPrintf("Connection dropped!\n")
}
plaintext, encrypted, state, toSend, err := conv.Receive(otrText)
if err != nil {
exitError(err)
}
if state == otr.ConversationEnded {
return
}
send(toSend)
if conv.IsEncrypted() {
fingerprint := string(conv.TheirPublicKey.Fingerprint())
if authorised && theirFingerprint != fingerprint {
exitPrintf("The contact changed mid-conversation.\n")
}
if !authorised {
theirFingerprint = fingerprint
authoriseRemember(fingerprint)
authorised = true
var w io.Writer
var r io.Reader
r, w = os.Stdin, os.Stdout
if execCommand != "" {
r, w = StartCommand(fingerprint)
}
go bufferedReadLoop(r, stdInChan)
go writeLoop(w, stdOutChan)
}
}
if len(plaintext) > 0 {
if !encrypted || !authorised {
exitPrintf("Received unencrypted or unauthenticated text.\n")
}
// fmt.Fprintf(os.Stderr, "Received %d bytes of plaintext.\n", len(plaintext))
stdOutChan <- plaintext
}
}
}
// We want to terminate the conversation. To do this, we send the
// termination messages, and wait for the other side to close the
// connection. It's important that these messages get through, for
// deniability.
toSend := conv.End()
send(toSend)
netOutChan <- nil
ShutdownLoop:
for {
select {
case _, alive := <-netInChan:
if !alive {
break ShutdownLoop
}
}
}
}
