Better support for rule attributes.

1. Make attributes into a dict so we can find them.
2. Add a function to decode some attributes to Python types.

Change-Id: I8d52a203818f5b24cf691cd2e86d52744d2ee191

2 files changed, 23 insertions, 12 deletions

diff --git a/tests/net_test/iproute.py b/tests/net_test/iproute.py
index a899cb74..b7f8ec58 100644
--- a/tests/net_test/iproute.py
+++ b/tests/net_test/iproute.py
@@ -109,6 +109,17 @@ EXPERIMENTAL_FRA_UID_START = 18
 EXPERIMENTAL_FRA_UID_END = 19
 
 
+def Decode(nla_type, nla_data):
+  if nla_type in [FRA_PRIORITY, FRA_FWMARK, FRA_TABLE,
+                  EXPERIMENTAL_FRA_UID_START, EXPERIMENTAL_FRA_UID_END]:
+    return struct.unpack("=I", nla_data)[0]
+  elif nla_type in [FRA_OIFNAME]:
+    return nla_data.strip("\x00")
+  else:
+    # Don't know what this is.
+    return nla_data
+
+
 def PaddedLength(length):
   # TODO: This padding is probably overly simplistic.
   return NLA_ALIGNTO * ((length / NLA_ALIGNTO) + (length % NLA_ALIGNTO != 0))
@@ -253,7 +264,7 @@ class IPRoute(object):
       self._Debug("  %s" % rtmsg)
 
       # Parse the attributes in the rtmsg.
-      attributes = []
+      attributes = {}
       bytesleft = nlmsghdr.length - len(nlmsghdr) - len(rtmsg)
       while bytesleft:
         # Read the nlattr header.
@@ -265,8 +276,13 @@ class IPRoute(object):
         padded_len = PaddedLength(nla.nla_len) - len(nla)
         nla_data, data = data[:datalen], data[padded_len:]
 
-        attributes.append((nla, nla_data))
-        self._Debug("    %s" % str(attributes[-1]))
+        # If it's an attribute we know about, try to decode it.
+        nla_data = Decode(nla.nla_type, nla_data)
+
+        if nla.nla_type in attributes:
+          raise ValueError("Duplicate attribute %d in rules")
+        attributes[nla.nla_type] = nla_data
+        self._Debug("    %s" % str((nla, nla_data)))
         bytesleft -= (padded_len + len(nla))
 
       rules.append((rtmsg, attributes))
diff --git a/tests/net_test/mark_test.py b/tests/net_test/mark_test.py
index 3411dd67..efae54d7 100755
--- a/tests/net_test/mark_test.py
+++ b/tests/net_test/mark_test.py
@@ -32,20 +32,15 @@ UDP_PAYLOAD = "hello"
 
 # Check to see if the kernel supports UID routing.
 def HaveUidRouting():
-  result = False
-
   # Create a rule with the UID range selector. If the kernel doesn't understand
   # the selector, it will create a rule with no selectors.
   iproute.IPRoute().UidRangeRule(6, True, 1000, 2000, 100)
 
-  # Dump dump all the rules. If we find a rule using the UID range selector,
-  # then the kernel supports UID range routing.
+  # Dump all the rules. If we find a rule using the UID range selector, then the
+  # kernel supports UID range routing.
   rules = iproute.IPRoute().DumpRules(6)
-  for unused_rtmsg, attributes in rules:
-    for (nla, unused_nla_data) in attributes:
-      if nla.nla_type == iproute.EXPERIMENTAL_FRA_UID_START:
-        result = True
-        break
+  result = any(iproute.EXPERIMENTAL_FRA_UID_START in attrs
+               for rule, attrs in rules)
 
   # Delete the rule.
   iproute.IPRoute().UidRangeRule(6, False, 1000, 2000, 100)