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conn.go
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conn.go
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package imap
import (
"bufio"
"io"
"net"
)
// A connection state.
// See RFC 3501 section 3.
type ConnState int
const (
// In the connecting state, the server has not yet sent a greeting and no
// command can be issued.
ConnectingState = 0
// In the not authenticated state, the client MUST supply
// authentication credentials before most commands will be
// permitted. This state is entered when a connection starts
// unless the connection has been pre-authenticated.
NotAuthenticatedState ConnState = 1 << 0
// In the authenticated state, the client is authenticated and MUST
// select a mailbox to access before commands that affect messages
// will be permitted. This state is entered when a
// pre-authenticated connection starts, when acceptable
// authentication credentials have been provided, after an error in
// selecting a mailbox, or after a successful CLOSE command.
AuthenticatedState = 1 << 1
// In a selected state, a mailbox has been selected to access.
// This state is entered when a mailbox has been successfully
// selected.
SelectedState = AuthenticatedState + 1<<2
// In the logout state, the connection is being terminated. This
// state can be entered as a result of a client request (via the
// LOGOUT command) or by unilateral action on the part of either
// the client or server.
LogoutState = 1 << 3
// ConnectedState is either NotAuthenticatedState, AuthenticatedState or
// SelectedState.
ConnectedState = NotAuthenticatedState | AuthenticatedState | SelectedState
)
// A function that upgrades a connection.
//
// This should only be used by libraries implementing an IMAP extension (e.g.
// COMPRESS).
type ConnUpgrader func(conn net.Conn) (net.Conn, error)
type debugWriter struct {
io.Writer
local io.Writer
remote io.Writer
}
// NewDebugWriter creates a new io.Writer that will write local network activity
// to local and remote network activity to remote.
func NewDebugWriter(local, remote io.Writer) io.Writer {
return &debugWriter{Writer: local, local: local, remote: remote}
}
type multiFlusher struct {
flushers []flusher
}
func (mf *multiFlusher) Flush() error {
for _, f := range mf.flushers {
if err := f.Flush(); err != nil {
return err
}
}
return nil
}
func newMultiFlusher(flushers ...flusher) flusher {
return &multiFlusher{flushers}
}
// An IMAP connection.
type Conn struct {
net.Conn
*Reader
*Writer
br *bufio.Reader
bw *bufio.Writer
waits chan struct{}
// Print all commands and responses to this io.Writer.
debug io.Writer
}
// NewConn creates a new IMAP connection.
func NewConn(conn net.Conn, r *Reader, w *Writer) *Conn {
c := &Conn{Conn: conn, Reader: r, Writer: w}
c.init()
return c
}
func (c *Conn) init() {
r := io.Reader(c.Conn)
w := io.Writer(c.Conn)
if c.debug != nil {
localDebug, remoteDebug := c.debug, c.debug
if debug, ok := c.debug.(*debugWriter); ok {
localDebug, remoteDebug = debug.local, debug.remote
}
if localDebug != nil {
w = io.MultiWriter(c.Conn, localDebug)
}
if remoteDebug != nil {
r = io.TeeReader(c.Conn, remoteDebug)
}
}
if c.br == nil {
c.br = bufio.NewReader(r)
c.Reader.reader = c.br
} else {
c.br.Reset(r)
}
if c.bw == nil {
c.bw = bufio.NewWriter(w)
c.Writer.Writer = c.bw
} else {
c.bw.Reset(w)
}
if f, ok := c.Conn.(flusher); ok {
c.Writer.Writer = struct {
io.Writer
flusher
}{
c.bw,
newMultiFlusher(c.bw, f),
}
}
}
// Write implements io.Writer.
func (c *Conn) Write(b []byte) (n int, err error) {
return c.Writer.Write(b)
}
// Flush writes any buffered data to the underlying connection.
func (c *Conn) Flush() error {
return c.Writer.Flush()
}
// Upgrade a connection, e.g. wrap an unencrypted connection with an encrypted
// tunnel.
func (c *Conn) Upgrade(upgrader ConnUpgrader) error {
// Flush all buffered data
if err := c.Flush(); err != nil {
return err
}
// Block reads and writes during the upgrading process
c.waits = make(chan struct{})
defer close(c.waits)
upgraded, err := upgrader(c.Conn)
if err != nil {
return err
}
c.Conn = upgraded
c.init()
return nil
}
// Wait waits for the connection to be ready for reads and writes.
func (c *Conn) Wait() {
if c.waits != nil {
<-c.waits
}
}
// SetDebug defines an io.Writer to which all network activity will be logged.
// If nil is provided, network activity will not be logged.
func (c *Conn) SetDebug(w io.Writer) {
c.debug = w
c.init()
}