PortconProtocol: add support for specifiying by protocol string

Leverage Python lib socket.getprotobyname()

setools/policyrep/netcontext.py

@@ -16,7 +16,7 @@
 # License along with SETools.  If not, see
 # <http://www.gnu.org/licenses/>.
 #
-import socket
+from socket import IPPROTO_TCP, IPPROTO_UDP, getprotobyname
 from collections import namedtuple
 
 from . import qpol
@@ -146,16 +146,22 @@ class PortconProtocol(int):
     corresponding protocol string (udp, tcp).
     """
 
-    _proto_to_text = {socket.IPPROTO_TCP: 'tcp',
-                      socket.IPPROTO_UDP: 'udp'}
+    _proto_to_text = {IPPROTO_TCP: 'tcp',
+                      IPPROTO_UDP: 'udp'}
 
     def __new__(cls, value):
-        if value not in cls._proto_to_text:
-            raise ValueError("{0} is not a supported IP protocol number. "
-                             "Values such as {1} (TCP) or {2} (UDP) should be used.".
-                             format(value, socket.IPPROTO_TCP, socket.IPPROTO_UDP))
+        try:
+            # convert string representation
+            num = getprotobyname(value)
+        except TypeError:
+            num = value
 
-        return super(PortconProtocol, cls).__new__(cls, value)
+        if num not in cls._proto_to_text:
+            raise ValueError("{0} is not a supported IP protocol. "
+                             "Values such as {1} (TCP) or {2} (UDP) should be used.".
+                             format(value, IPPROTO_TCP, IPPROTO_UDP))
+
+        return super(PortconProtocol, cls).__new__(cls, num)
 
     def __str__(self):
         return self._proto_to_text[self]