Allow JIDs without localpart.

CHANGELOG.md

@@ -7,6 +7,7 @@
 ### Changed
 - Print `--help` output to stdout instead of stderr.
 - Print sent stanzas when `--debug` is used (via go-xmpp commit 9129a110df1b).
+- Allow JIDs without localpart.
 
 ## [v0.5.6] 2022-11-11
 ### Added

jid.go

@@ -50,7 +50,7 @@ func MarshalJID(input string) (string, error) {
 	switch {
 	case sep == -1:
 		// There is no @ sign, and therefore no localpart.
-		return input, errors.New("Invalid JID: " + input)
+		domainpart = s
 	case sep == 0:
 		// The JID starts with an @ sign (invalid empty localpart)
 		err = errors.New("Invalid JID:" + input)
@@ -71,17 +71,24 @@ func MarshalJID(input string) (string, error) {
 	//    are taken.
 
 	domainpart = strings.TrimSuffix(domainpart, ".")
+	var jid string
 
 	if !utf8.ValidString(localpart) || !utf8.ValidString(domainpart) || !utf8.ValidString(resourcepart) {
 		return input, errors.New("Invalid JID: " + input)
 	}
 
-	if localpart == "" || domainpart == "" {
+	if domainpart == "" {
 		return input, errors.New("Invalid JID: " + input)
 	}
 
+	if localpart == "" {
+		jid = domainpart
+	} else {
+		jid = localpart + "@" + domainpart
+	}
+
 	if resourcepart == "" {
-		return localpart + "@" + domainpart, err
+		return jid, err
 	}
-	return localpart + "@" + domainpart + "/" + resourcepart, err
+	return jid + "/" + resourcepart, err
 }