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package client
import (
"crypto/tls"
"errors"
"net"
"github.com/emersion/go-imap"
"github.com/emersion/go-imap/commands"
"github.com/emersion/go-imap/responses"
"github.com/emersion/go-sasl"
)
var (
// ErrAlreadyLoggedIn is returned if Login or Authenticate is called when the
// client is already logged in.
ErrAlreadyLoggedIn = errors.New("Already logged in")
// ErrTLSAlreadyEnabled is returned if StartTLS is called when TLS is already
// enabled.
ErrTLSAlreadyEnabled = errors.New("TLS is already enabled")
// ErrLoginDisabled is returned if Login or Authenticate is called when the
// server has disabled authentication. Most of the time, calling enabling TLS
// solves the problem.
ErrLoginDisabled = errors.New("Login is disabled in current state")
)
// SupportStartTLS checks if the server supports STARTTLS.
func (c *Client) SupportStartTLS() (bool, error) {
return c.Support("STARTTLS")
}
// StartTLS starts TLS negotiation.
func (c *Client) StartTLS(tlsConfig *tls.Config) error {
if c.isTLS {
return ErrTLSAlreadyEnabled
}
if tlsConfig == nil {
tlsConfig = new(tls.Config)
}
if tlsConfig.ServerName == "" {
tlsConfig = tlsConfig.Clone()
tlsConfig.ServerName = c.serverName
}
cmd := new(commands.StartTLS)
err := c.Upgrade(func(conn net.Conn) (net.Conn, error) {
// Flag connection as in upgrading
c.upgrading = true
if status, err := c.execute(cmd, nil); err != nil {
return nil, err
} else if err := status.Err(); err != nil {
return nil, err
}
// Wait for reader to block.
c.conn.WaitReady()
tlsConn := tls.Client(conn, tlsConfig)
if err := tlsConn.Handshake(); err != nil {
return nil, err
}
// Capabilities change when TLS is enabled
c.locker.Lock()
c.caps = nil
c.locker.Unlock()
return tlsConn, nil
})
if err != nil {
return err
}
c.isTLS = true
return nil
}
// SupportAuth checks if the server supports a given authentication mechanism.
func (c *Client) SupportAuth(mech string) (bool, error) {
return c.Support("AUTH=" + mech)
}
// Authenticate indicates a SASL authentication mechanism to the server. If the
// server supports the requested authentication mechanism, it performs an
// authentication protocol exchange to authenticate and identify the client.
func (c *Client) Authenticate(auth sasl.Client) error {
if c.State() != imap.NotAuthenticatedState {
return ErrAlreadyLoggedIn
}
mech, ir, err := auth.Start()
if err != nil {
return err
}
cmd := &commands.Authenticate{
Mechanism: mech,
}
irOk, err := c.Support("SASL-IR")
if err != nil {
return err
}
if irOk {
cmd.InitialResponse = ir
}
res := &responses.Authenticate{
Mechanism: auth,
InitialResponse: ir,
RepliesCh: make(chan []byte, 10),
}
if irOk {
res.InitialResponse = nil
}
status, err := c.execute(cmd, res)
if err != nil {
return err
}
if err = status.Err(); err != nil {
return err
}
c.locker.Lock()
c.state = imap.AuthenticatedState
c.caps = nil // Capabilities change when user is logged in
c.locker.Unlock()
if status.Code == "CAPABILITY" {
c.gotStatusCaps(status.Arguments)
}
return nil
}
// Login identifies the client to the server and carries the plaintext password
// authenticating this user.
func (c *Client) Login(username, password string) error {
if state := c.State(); state == imap.AuthenticatedState || state == imap.SelectedState {
return ErrAlreadyLoggedIn
}
c.locker.Lock()
loginDisabled := c.caps != nil && c.caps["LOGINDISABLED"]
c.locker.Unlock()
if loginDisabled {
return ErrLoginDisabled
}
cmd := &commands.Login{
Username: username,
Password: password,
}
status, err := c.execute(cmd, nil)
if err != nil {
return err
}
if err = status.Err(); err != nil {
return err
}
c.locker.Lock()
c.state = imap.AuthenticatedState
c.caps = nil // Capabilities change when user is logged in
c.locker.Unlock()
if status.Code == "CAPABILITY" {
c.gotStatusCaps(status.Arguments)
}
return nil
}
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