uhh whats a submodule i have never heard of that bro

go-xmpp/auth.go

@@ -0,0 +1,105 @@
+package xmpp
+
+import (
+	"encoding/base64"
+	"encoding/xml"
+	"errors"
+	"fmt"
+	"io"
+
+	"gosrc.io/xmpp/stanza"
+)
+
+// Credential is used to pass the type of secret that will be used to connect to XMPP server.
+// It can be either a password or an OAuth 2 bearer token.
+type Credential struct {
+	secret     string
+	mechanisms []string
+}
+
+func Password(pwd string) Credential {
+	credential := Credential{
+		secret:     pwd,
+		mechanisms: []string{"PLAIN"},
+	}
+	return credential
+}
+
+func OAuthToken(token string) Credential {
+	credential := Credential{
+		secret:     token,
+		mechanisms: []string{"X-OAUTH2"},
+	}
+	return credential
+}
+
+// ============================================================================
+// Authentication flow for SASL mechanisms
+
+func authSASL(socket io.ReadWriter, decoder *xml.Decoder, f stanza.StreamFeatures, user string, credential Credential) (err error) {
+	var matchingMech string
+	for _, mech := range credential.mechanisms {
+		if isSupportedMech(mech, f.Mechanisms.Mechanism) {
+			matchingMech = mech
+			break
+		}
+	}
+
+	switch matchingMech {
+	case "PLAIN", "X-OAUTH2":
+		// TODO: Implement other type of SASL mechanisms
+		return authPlain(socket, decoder, matchingMech, user, credential.secret)
+	default:
+		err := fmt.Errorf("no matching authentication (%v) supported by server: %v", credential.mechanisms, f.Mechanisms.Mechanism)
+		return NewConnError(err, true)
+	}
+}
+
+// Plain authentication: send base64-encoded \x00 user \x00 password
+func authPlain(socket io.ReadWriter, decoder *xml.Decoder, mech string, user string, secret string) error {
+	raw := "\x00" + user + "\x00" + secret
+	enc := make([]byte, base64.StdEncoding.EncodedLen(len(raw)))
+	base64.StdEncoding.Encode(enc, []byte(raw))
+
+	a := stanza.SASLAuth{
+		Mechanism: mech,
+		Value:     string(enc),
+	}
+	data, err := xml.Marshal(a)
+	if err != nil {
+		return err
+	}
+	n, err := socket.Write(data)
+	if err != nil {
+		return err
+	} else if n == 0 {
+		return errors.New("failed to write authSASL nonza to socket : wrote 0 bytes")
+	}
+
+	// Next message should be either success or failure.
+	val, err := stanza.NextPacket(decoder)
+	if err != nil {
+		return err
+	}
+
+	switch v := val.(type) {
+	case stanza.SASLSuccess:
+	case stanza.SASLFailure:
+		// v.Any is type of sub-element in failure, which gives a description of what failed.
+		err := errors.New("auth failure: " + v.Any.Local)
+		return NewConnError(err, true)
+	default:
+		return errors.New("expected SASL success or failure, got " + v.Name())
+	}
+	return err
+}
+
+// isSupportedMech returns true if the mechanism is supported in the provided list.
+func isSupportedMech(mech string, mechanisms []string) bool {
+	for _, m := range mechanisms {
+		if mech == m {
+			return true
+		}
+	}
+	return false
+}