gh-96035: Make urllib.parse.urlparse reject non-numeric ports (#98273)

Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>

Lib/urllib/parse.py

@@ -167,12 +167,11 @@ class _NetlocResultMixinBase(object):
     def port(self):
         port = self._hostinfo[1]
         if port is not None:
-            try:
-                port = int(port, 10)
-            except ValueError:
-                message = f'Port could not be cast to integer value as {port!r}'
-                raise ValueError(message) from None
-            if not ( 0 <= port <= 65535):
+            if port.isdigit() and port.isascii():
+                port = int(port)
+            else:
+                raise ValueError(f"Port could not be cast to integer value as {port!r}")
+            if not (0 <= port <= 65535):
                 raise ValueError("Port out of range 0-65535")
         return port
 
@@ -1132,15 +1131,15 @@ def splitnport(host, defport=-1):
 def _splitnport(host, defport=-1):
     """Split host and port, returning numeric port.
     Return given default port if no ':' found; defaults to -1.
-    Return numerical port if a valid number are found after ':'.
+    Return numerical port if a valid number is found after ':'.
     Return None if ':' but not a valid number."""
     host, delim, port = host.rpartition(':')
     if not delim:
         host = port
     elif port:
-        try:
+        if port.isdigit() and port.isascii():
             nport = int(port)
-        except ValueError:
+        else:
             nport = None
         return host, nport
     return host, defport