imap: add timeout to tcp connect functions

Extract the tcp connection details and timeout the tcp connect functions
(net.ResolveTCPAddr and net.DialTCP). If timed out, ensure that the
connection is properly closed.

Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

1 files changed, 10 insertions, 120 deletions

diff --git a/worker/imap/worker.go b/worker/imap/worker.go
index 1ff6341f..eabaae02 100644
--- a/worker/imap/worker.go
+++ b/worker/imap/worker.go
@@ -1,9 +1,7 @@
 package imap
 
 import (
-	"crypto/tls"
 	"fmt"
-	"net"
 	"net/url"
 	"time"
 
@@ -25,6 +23,7 @@ func init() {
 
 var (
 	errUnsupported      = fmt.Errorf("unsupported command")
+	errClientNotReady   = fmt.Errorf("client not ready")
 	errNotConnected     = fmt.Errorf("not connected")
 	errAlreadyConnected = fmt.Errorf("already connected")
 )
@@ -93,6 +92,15 @@ func (w *IMAPWorker) handleMessage(msg types.WorkerMessage) error {
 
 	var reterr error // will be returned at the end, needed to support idle
 
+	// when client is nil allow only certain messages to be handled
+	if w.client == nil {
+		switch msg.(type) {
+		case *types.Connect, *types.Reconnect, *types.Disconnect, *types.Configure:
+		default:
+			return errClientNotReady
+		}
+	}
+
 	// set connection timeout for calls to imap server
 	if w.client != nil {
 		w.client.Timeout = w.config.connection_timeout
@@ -251,124 +259,6 @@ func (w *IMAPWorker) handleImapUpdate(update client.Update) {
 	}
 }
 
-func (w *IMAPWorker) connect() (*client.Client, error) {
-	var (
-		conn *net.TCPConn
-		c    *client.Client
-	)
-
-	addr, err := net.ResolveTCPAddr("tcp", w.config.addr)
-	if err != nil {
-		return nil, err
-	}
-
-	conn, err = net.DialTCP("tcp", nil, addr)
-	if err != nil {
-		return nil, err
-	}
-
-	if w.config.connection_timeout > 0 {
-		end := time.Now().Add(w.config.connection_timeout)
-		err = conn.SetDeadline(end)
-		if err != nil {
-			return nil, err
-		}
-	}
-	if w.config.keepalive_period > 0 {
-		err = w.setKeepaliveParameters(conn)
-		if err != nil {
-			return nil, err
-		}
-	}
-
-	serverName, _, _ := net.SplitHostPort(w.config.addr)
-	tlsConfig := &tls.Config{ServerName: serverName}
-
-	switch w.config.scheme {
-	case "imap":
-		c, err = client.New(conn)
-		if err != nil {
-			return nil, err
-		}
-		if !w.config.insecure {
-			if err = c.StartTLS(tlsConfig); err != nil {
-				return nil, err
-			}
-		}
-	case "imaps":
-		tlsConn := tls.Client(conn, tlsConfig)
-		c, err = client.New(tlsConn)
-		if err != nil {
-			return nil, err
-		}
-	default:
-		return nil, fmt.Errorf("Unknown IMAP scheme %s", w.config.scheme)
-	}
-
-	c.ErrorLog = w.worker.Logger
-
-	if w.config.user != nil {
-		username := w.config.user.Username()
-		password, hasPassword := w.config.user.Password()
-		if !hasPassword {
-			// TODO: ask password
-		}
-
-		if w.config.oauthBearer.Enabled {
-			if err := w.config.oauthBearer.Authenticate(
-				username, password, c); err != nil {
-				return nil, err
-			}
-		} else if err := c.Login(username, password); err != nil {
-			return nil, err
-		}
-	}
-
-	c.SetDebug(w.worker.Logger.Writer())
-
-	if _, err := c.Select(imap.InboxName, false); err != nil {
-		return nil, err
-	}
-
-	return c, nil
-}
-
-// Set additional keepalive parameters.
-// Uses new interfaces introduced in Go1.11, which let us get connection's file
-// descriptor, without blocking, and therefore without uncontrolled spawning of
-// threads (not goroutines, actual threads).
-func (w *IMAPWorker) setKeepaliveParameters(conn *net.TCPConn) error {
-	err := conn.SetKeepAlive(true)
-	if err != nil {
-		return err
-	}
-	// Idle time before sending a keepalive probe
-	err = conn.SetKeepAlivePeriod(w.config.keepalive_period)
-	if err != nil {
-		return err
-	}
-	rawConn, e := conn.SyscallConn()
-	if e != nil {
-		return e
-	}
-	err = rawConn.Control(func(fdPtr uintptr) {
-		fd := int(fdPtr)
-		// Max number of probes before failure
-		err := lib.SetTcpKeepaliveProbes(fd, w.config.keepalive_probes)
-		if err != nil {
-			w.worker.Logger.Printf(
-				"cannot set tcp keepalive probes: %v\n", err)
-		}
-		// Wait time after an unsuccessful probe
-		err = lib.SetTcpKeepaliveInterval(fd, w.config.keepalive_interval)
-		if err != nil {
-			w.worker.Logger.Printf(
-				"cannot set tcp keepalive interval: %v\n", err)
-		}
-	})
-	return err
-}
-
 func (w *IMAPWorker) Run() {
 	for {
 		select {