idn-hostname validation.

2 files changed, 15 insertions, 0 deletions

diff --git a/jsonschema/_format.py b/jsonschema/_format.py
index a06136c..e06f540 100644
--- a/jsonschema/_format.py
+++ b/jsonschema/_format.py
@@ -219,6 +219,20 @@ def is_host_name(instance):
 
 
 try:
+    # The built-in `idna` codec only implements RFC 3890, so we go elsewhere.
+    import idna
+except ImportError:
+    pass
+else:
+    @_checks_drafts(draft7="idn-hostname", raises=idna.IDNAError)
+    def is_idn_host_name(instance):
+        if not isinstance(instance, str_types):
+            return True
+        idna.encode(instance)
+        return True
+
+
+try:
     import rfc3987
 except ImportError:
     pass
diff --git a/setup.cfg b/setup.cfg
index 99e0702..2219f8a 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -33,6 +33,7 @@ install_requires =
 
 [options.extras_require]
 format =
+    idna
     jsonpointer>1.13
     rfc3987
     strict-rfc3339