This is the v1 version, had the v2 before.

responses/authenticate.go

@@ -0,0 +1,61 @@
+package responses
+
+import (
+	"encoding/base64"
+
+	"github.com/emersion/go-imap"
+	"github.com/emersion/go-sasl"
+)
+
+// An AUTHENTICATE response.
+type Authenticate struct {
+	Mechanism       sasl.Client
+	InitialResponse []byte
+	RepliesCh       chan []byte
+}
+
+// Implements
+func (r *Authenticate) Replies() <-chan []byte {
+	return r.RepliesCh
+}
+
+func (r *Authenticate) writeLine(l string) error {
+	r.RepliesCh <- []byte(l + "\r\n")
+	return nil
+}
+
+func (r *Authenticate) cancel() error {
+	return r.writeLine("*")
+}
+
+func (r *Authenticate) Handle(resp imap.Resp) error {
+	cont, ok := resp.(*imap.ContinuationReq)
+	if !ok {
+		return ErrUnhandled
+	}
+
+	// Empty challenge, send initial response as stated in RFC 2222 section 5.1
+	if cont.Info == "" && r.InitialResponse != nil {
+		encoded := base64.StdEncoding.EncodeToString(r.InitialResponse)
+		if err := r.writeLine(encoded); err != nil {
+			return err
+		}
+		r.InitialResponse = nil
+		return nil
+	}
+
+	challenge, err := base64.StdEncoding.DecodeString(cont.Info)
+	if err != nil {
+		r.cancel()
+		return err
+	}
+
+	reply, err := r.Mechanism.Next(challenge)
+	if err != nil {
+		r.cancel()
+		return err
+	}
+
+	encoded := base64.StdEncoding.EncodeToString(reply)
+	return r.writeLine(encoded)
+}