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https://github.com/jhillyerd/inbucket.git
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Add empty shell of POP3 server
This commit is contained in:
James Hillyerd
305
pop3d/handler.go
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305
pop3d/handler.go
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@@ -0,0 +1,305 @@
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package pop3d
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import (
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"bufio"
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"bytes"
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//"container/list"
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"fmt"
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"github.com/jhillyerd/inbucket/log"
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"io"
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"net"
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//"strconv"
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"strings"
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"time"
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)
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type State int
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const (
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AUTHORIZATION State = iota // The client must now identify and authenticate
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TRANSACTION // Mailbox open, client may now issue commands
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UPDATE // Purge deleted messages, cleanup
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QUIT
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)
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func (s State) String() string {
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switch s {
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case AUTHORIZATION:
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return "AUTHORIZATION"
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case TRANSACTION:
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return "TRANSACTION"
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case UPDATE:
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return "UPDATE"
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case QUIT:
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return "QUIT"
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}
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return "Unknown"
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}
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var commands = map[string]bool{
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"QUIT": true,
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"STAT": true,
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"LIST": true,
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"RETR": true,
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"DELE": true,
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"NOOP": true,
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"RSET": true,
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"TOP": true,
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"UIDL": true,
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"USER": true,
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"PASS": true,
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"APOP": true,
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}
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type Session struct {
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server *Server
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id int
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conn net.Conn
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remoteHost string
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sendError error
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state State
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reader *bufio.Reader
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user string
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}
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func NewSession(server *Server, id int, conn net.Conn) *Session {
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reader := bufio.NewReader(conn)
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host, _, _ := net.SplitHostPort(conn.RemoteAddr().String())
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return &Session{server: server, id: id, conn: conn, state: AUTHORIZATION,
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reader: reader, remoteHost: host}
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}
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func (ses *Session) String() string {
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return fmt.Sprintf("Session{id: %v, state: %v}", ses.id, ses.state)
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}
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/* Session flow:
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* 1. Send initial greeting
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* 2. Receive cmd
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* 3. If good cmd, respond, optionally change state
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* 4. If bad cmd, respond error
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* 5. Goto 2
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*/
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func (s *Server) startSession(id int, conn net.Conn) {
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log.Info("Connection from %v, starting session <%v>", conn.RemoteAddr(), id)
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//expConnectsCurrent.Add(1)
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defer func() {
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conn.Close()
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s.waitgroup.Done()
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//expConnectsCurrent.Add(-1)
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}()
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ses := NewSession(s, id, conn)
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ses.greet()
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// This is our command reading loop
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for ses.state != QUIT && ses.sendError == nil {
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line, err := ses.readLine()
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if err == nil {
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if cmd, arg, ok := ses.parseCmd(line); ok {
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// Check against valid SMTP commands
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if cmd == "" {
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ses.send("-ERR Speak up")
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continue
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}
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if !commands[cmd] {
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ses.send(fmt.Sprintf("-ERR Syntax error, %v command unrecognized", cmd))
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ses.warn("Unrecognized command: %v", cmd)
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continue
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}
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// Commands we handle in any state
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switch cmd {
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case "APOP", "TOP":
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// These commands are not implemented in any state
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ses.send(fmt.Sprintf("-ERR %v command not implemented", cmd))
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ses.warn("Command %v not implemented by Inbucket", cmd)
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continue
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case "NOOP":
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// TODO move to transaction state
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ses.send("+OK I have sucessfully done nothing")
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continue
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case "RSET":
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// TODO move to transaction state
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// Reset session
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ses.trace("Resetting session state on RSET request")
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ses.reset()
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ses.send("+OK Session reset")
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continue
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case "QUIT":
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// TODO should be handled differently by transaciton
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ses.send("+OK Goodnight and good luck")
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ses.enterState(QUIT)
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continue
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}
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// Send command to handler for current state
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switch ses.state {
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case AUTHORIZATION:
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ses.authorizationHandler(cmd, arg)
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continue
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case TRANSACTION:
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//ses.transactionHandler(cmd, arg)
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continue
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case UPDATE:
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//ses.updateHandler(cmd, arg)
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continue
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}
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ses.error("Session entered unexpected state %v", ses.state)
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break
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} else {
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ses.send("-ERR Syntax error, command garbled")
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}
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} else {
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// readLine() returned an error
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if err == io.EOF {
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switch ses.state {
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case AUTHORIZATION:
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// EOF is common here
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ses.info("Client closed connection (state %v)", ses.state)
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default:
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ses.warn("Got EOF while in state %v", ses.state)
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}
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break
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}
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// not an EOF
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ses.warn("Connection error: %v", err)
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if netErr, ok := err.(net.Error); ok {
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if netErr.Timeout() {
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ses.send("-ERR Idle timeout, bye bye")
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break
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}
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}
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ses.send("-ERR Connection error, sorry")
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break
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}
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}
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if ses.sendError != nil {
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ses.warn("Network send error: %v", ses.sendError)
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}
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ses.info("Closing connection")
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}
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// AUTHORIZATION state
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func (ses *Session) authorizationHandler(cmd string, arg []string) {
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switch cmd {
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case "HELO":
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ses.send("250 Great, let's get this show on the road")
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//ses.enterState(READY)
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case "EHLO":
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ses.send("250-Great, let's get this show on the road")
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ses.send("250-8BITMIME")
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//ses.enterState(READY)
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default:
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ses.ooSeq(cmd)
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}
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}
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func (ses *Session) enterState(state State) {
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ses.state = state
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ses.trace("Entering state %v", state)
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}
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func (ses *Session) greet() {
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ses.send("+OK Inbucket POP3 server ready")
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}
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// Calculate the next read or write deadline based on maxIdleSeconds
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func (ses *Session) nextDeadline() time.Time {
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return time.Now().Add(time.Duration(ses.server.maxIdleSeconds) * time.Second)
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}
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// Send requested message, store errors in Session.sendError
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func (ses *Session) send(msg string) {
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if err := ses.conn.SetWriteDeadline(ses.nextDeadline()); err != nil {
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ses.sendError = err
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return
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}
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if _, err := fmt.Fprint(ses.conn, msg+"\r\n"); err != nil {
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ses.sendError = err
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ses.warn("Failed to send: '%v'", msg)
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return
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}
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ses.trace(">> %v >>", msg)
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}
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// readByteLine reads a line of input into the provided buffer. Does
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// not reset the Buffer - please do so prior to calling.
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func (ses *Session) readByteLine(buf *bytes.Buffer) error {
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if err := ses.conn.SetReadDeadline(ses.nextDeadline()); err != nil {
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return err
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}
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for {
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line, err := ses.reader.ReadBytes('\r')
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if err != nil {
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return err
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}
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buf.Write(line)
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// Read the next byte looking for '\n'
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c, err := ses.reader.ReadByte()
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if err != nil {
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return err
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}
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buf.WriteByte(c)
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if c == '\n' {
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// We've reached the end of the line, return
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return nil
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}
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// Else, keep looking
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}
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// Should be unreachable
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return nil
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}
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// Reads a line of input
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func (ses *Session) readLine() (line string, err error) {
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if err = ses.conn.SetReadDeadline(ses.nextDeadline()); err != nil {
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return "", err
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}
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line, err = ses.reader.ReadString('\n')
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if err != nil {
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return "", err
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}
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ses.trace("<< %v <<", strings.TrimRight(line, "\r\n"))
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return line, nil
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}
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func (ses *Session) parseCmd(line string) (cmd string, args []string, ok bool) {
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line = strings.TrimRight(line, "\r\n")
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if len(line) == 0 {
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return "", nil, true
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}
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words := strings.Split(line, " ")
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return strings.ToUpper(words[0]), words[1:], true
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}
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func (ses *Session) reset() {
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//ses.enterState(READY)
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}
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func (ses *Session) ooSeq(cmd string) {
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ses.send(fmt.Sprintf("-ERR Command %v is out of sequence", cmd))
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ses.warn("Wasn't expecting %v here", cmd)
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}
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// Session specific logging methods
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func (ses *Session) trace(msg string, args ...interface{}) {
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log.Trace("%v<%v> %v", ses.remoteHost, ses.id, fmt.Sprintf(msg, args...))
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}
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func (ses *Session) info(msg string, args ...interface{}) {
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log.Info("%v<%v> %v", ses.remoteHost, ses.id, fmt.Sprintf(msg, args...))
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}
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func (ses *Session) warn(msg string, args ...interface{}) {
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// Update metrics
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//expWarnsTotal.Add(1)
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log.Warn("%v<%v> %v", ses.remoteHost, ses.id, fmt.Sprintf(msg, args...))
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}
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func (ses *Session) error(msg string, args ...interface{}) {
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// Update metrics
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//expErrorsTotal.Add(1)
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log.Error("%v<%v> %v", ses.remoteHost, ses.id, fmt.Sprintf(msg, args...))
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}
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