Initial commit

vendor/github.com/emersion/go-imap/server/cmd_noauth.go

@@ -0,0 +1,127 @@
+package server
+
+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"
+)
+
+// IMAP errors in Not Authenticated state.
+var (
+	ErrAlreadyAuthenticated = errors.New("Already authenticated")
+	ErrAuthDisabled         = errors.New("Authentication disabled")
+)
+
+type StartTLS struct {
+	commands.StartTLS
+}
+
+func (cmd *StartTLS) Handle(conn Conn) error {
+	ctx := conn.Context()
+	if ctx.State != imap.NotAuthenticatedState {
+		return ErrAlreadyAuthenticated
+	}
+	if conn.IsTLS() {
+		return errors.New("TLS is already enabled")
+	}
+	if conn.Server().TLSConfig == nil {
+		return errors.New("TLS support not enabled")
+	}
+
+	// Send an OK status response to let the client know that the TLS handshake
+	// can begin
+	return ErrStatusResp(&imap.StatusResp{
+		Type: imap.StatusOk,
+		Info: "Begin TLS negotiation now",
+	})
+}
+
+func (cmd *StartTLS) Upgrade(conn Conn) error {
+	tlsConfig := conn.Server().TLSConfig
+
+	var tlsConn *tls.Conn
+	err := conn.Upgrade(func(conn net.Conn) (net.Conn, error) {
+		tlsConn = tls.Server(conn, tlsConfig)
+		err := tlsConn.Handshake()
+		return tlsConn, err
+	})
+	if err != nil {
+		return err
+	}
+
+	conn.setTLSConn(tlsConn)
+
+	res := &responses.Capability{Caps: conn.Capabilities()}
+	return conn.WriteResp(res)
+}
+
+func afterAuthStatus(conn Conn) error {
+	return ErrStatusResp(&imap.StatusResp{
+		Type:      imap.StatusOk,
+		Code:      imap.CodeCapability,
+		Arguments: imap.FormatStringList(conn.Capabilities()),
+	})
+}
+
+func canAuth(conn Conn) bool {
+	for _, cap := range conn.Capabilities() {
+		if cap == "AUTH=PLAIN" {
+			return true
+		}
+	}
+	return false
+}
+
+type Login struct {
+	commands.Login
+}
+
+func (cmd *Login) Handle(conn Conn) error {
+	ctx := conn.Context()
+	if ctx.State != imap.NotAuthenticatedState {
+		return ErrAlreadyAuthenticated
+	}
+	if !canAuth(conn) {
+		return ErrAuthDisabled
+	}
+
+	user, err := conn.Server().Backend.Login(cmd.Username, cmd.Password)
+	if err != nil {
+		return err
+	}
+
+	ctx.State = imap.AuthenticatedState
+	ctx.User = user
+	return afterAuthStatus(conn)
+}
+
+type Authenticate struct {
+	commands.Authenticate
+}
+
+func (cmd *Authenticate) Handle(conn Conn) error {
+	ctx := conn.Context()
+	if ctx.State != imap.NotAuthenticatedState {
+		return ErrAlreadyAuthenticated
+	}
+	if !canAuth(conn) {
+		return ErrAuthDisabled
+	}
+
+	mechanisms := map[string]sasl.Server{}
+	for name, newSasl := range conn.Server().auths {
+		mechanisms[name] = newSasl(conn)
+	}
+
+	err := cmd.Authenticate.Handle(mechanisms, conn)
+	if err != nil {
+		return err
+	}
+
+	return afterAuthStatus(conn)
+}