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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
}