fix parsing SRV result with idna names. Fixes #4194

src/common/helpers.py

@@ -119,13 +119,23 @@ def parse_jid(jidstring):
 	return prep(*decompose_jid(jidstring))
 
 def idn_to_ascii(host):
-	'''convert IDN (Internationalized Domain Names) to ACE (ASCII-compatible encoding)'''
+	'''convert IDN (Internationalized Domain Names) to ACE
+	(ASCII-compatible encoding)'''
 	labels = idna.dots.split(host)
 	converted_labels = []
 	for label in labels:
 		converted_labels.append(idna.ToASCII(label))
 	return ".".join(converted_labels)
 
+def ascii_to_idn(host):
+	'''convert ACE (ASCII-compatible encoding) to IDN
+	(Internationalized Domain Names)'''
+	labels = idna.dots.split(host)
+	converted_labels = []
+	for label in labels:
+		converted_labels.append(idna.ToUnicode(label))
+	return ".".join(converted_labels)
+
 def parse_resource(resource):
 	'''Perform stringprep on resource and return it'''
 	if resource:

src/common/nslookup.py

@@ -109,13 +109,19 @@ class Resolver:
 		# _xmpp-client._tcp.jabber.org    service = 30 30 5222 jabber.org.
 		if not result: 
 			return []
+		ufqdn = helpers.ascii_to_idn(fqdn) # Unicode domain name
 		hosts = []
 		lines = result.split('\n')
 		for line in lines:
 			if line == '':
 				continue
+			domain = None
 			if line.startswith(fqdn):
-				rest = line[len(fqdn):].split('=')
+				domain = fqdn
+			elif line.startswith(ufqdn):
+				domain = ufqdn
+			if domain:
+				rest = line[len(host):].split('=')
 				if len(rest) != 2:
 					continue
 				answer_type, props_str = rest