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)) _, err := fmt.Fprintf(socket, "%s", stanza.NSSASL, mech, enc) if err != nil { return err } // 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 }