1 files changed, 22 insertions, 0 deletions
diff --git a/netlib/check.py b/netlib/check.py
new file mode 100644
index 00000000..7b007cb5
--- /dev/null
+++ b/netlib/check.py
@@ -0,0 +1,22 @@
+import re
+
+_label_valid = re.compile(b"(?!-)[A-Z\d-]{1,63}(?<!-)$", re.IGNORECASE)
+
+
+def is_valid_host(host: bytes) -> bool:
+    """
+        Checks if a hostname is valid.
+    """
+    try:
+        host.decode("idna")
+    except ValueError:
+        return False
+    if len(host) > 255:
+        return False
+    if host and host[-1:] == b".":
+        host = host[:-1]
+    return all(_label_valid.match(x) for x in host.split(b"."))
+
+
+def is_valid_port(port):
+    return 0 <= port <= 65535