Move SASL mechanism detection to xmpp/sasl.go

2 files changed, 35 insertions, 25 deletions

diff --git a/xmpp/sasl.go b/xmpp/sasl.go
index 8687782..e06bcd5 100644
--- a/xmpp/sasl.go
+++ b/xmpp/sasl.go
@@ -34,3 +34,33 @@ func (s *session) sasl() {
 		}
 	}
 }
+
+// hasSaslPlain scans the given stream features XML element for the SASL PLAIN
+// mechanism which is supported by xengineering.eu/limox/xmpp. It returns true
+// if the stream has support for this mechanism and false otherwise.
+func hasSaslPlain(e []xml.Token) bool {
+	mechanism := xml.Name{`urn:ietf:params:xml:ns:xmpp-sasl`, `mechanism`}
+
+	for i, t := range e {
+		switch s := t.(type) {
+		case xml.StartElement:
+			if s.Name == mechanism {
+				if i+1 < len(e) {
+					subtype := func() string {
+						switch c := e[i+1].(type) {
+						case xml.CharData:
+							return string(c)
+						default:
+							return ""
+						}
+					}()
+					if subtype == `PLAIN` {
+						return true
+					}
+				}
+			}
+		}
+	}
+
+	return false
+}
diff --git a/xmpp/stream_pair.go b/xmpp/stream_pair.go
index b353947..8f70318 100644
--- a/xmpp/stream_pair.go
+++ b/xmpp/stream_pair.go
@@ -91,31 +91,11 @@ func closeStream(s *session) {
 	}
 }
 
-func getCharData(t xml.Token) string {
-	switch c := t.(type) {
-	case xml.CharData:
-		return string(c)
-	default:
-		return ""
-	}
-}
-
 func streamFeaturesHandler(e []xml.Token) {
-	mechanism := xml.Name{`urn:ietf:params:xml:ns:xmpp-sasl`, `mechanism`}
-
-	for i, t := range e {
-		switch s := t.(type) {
-		case xml.StartElement:
-			if s.Name == mechanism {
-				if i+1 < len(e) {
-					if getCharData(e[i+1]) == `PLAIN` {
-						log.Println("Got offer for SASL PLAIN")
-						return
-					}
-				}
-			}
-		}
+	sasl := hasSaslPlain(e)
+	if sasl {
+		log.Println("Stream is compatible with SASL PLAIN mechanism")
+	} else {
+		log.Println("Stream is not compatible with SASL PLAIN mechanism!")
 	}
-
-	log.Println("No compatible SASL mechanism offered!")
 }