Workaround a bug in Twisted's zone file parsing.

[invirt/packages/invirt-dns.git] / invirt-dns

diff --git a/invirt-dns b/invirt-dns
index b540ff7..188d1ce 100755 (executable)
--- a/invirt-dns
+++ b/invirt-dns
@@ -16,6 +16,7 @@ import psycopg2
 import sqlalchemy
 import time
 import re
+import sys
 
 class DatabaseAuthority(common.ResolverBase):
     """An Authority that is loaded from a file."""
@@ -214,20 +215,37 @@ class DelegatingQuotingBindAuthority(authority.BindAuthority):
             L.append(split_line)
         return filter(None, L)
 
+    # See https://twistedmatrix.com/documents/13.1.0/api/twisted.internet.defer.html#inlineCallbacks
+    @defer.inlineCallbacks
     def _lookup(self, name, cls, type, timeout = None):
-        maybeDelegate = False
-        deferredResult = authority.BindAuthority._lookup(self, name, cls,
-                                                         type, timeout)
-        # If we didn't find an exact match for the name we were seeking,
-        # check if it's within a subdomain we're supposed to delegate to
-        # some other DNS server.
-        while (isinstance(deferredResult.result, failure.Failure)
-               and '.' in name):
-            maybeDelegate = True
-            name = name[name.find('.') + 1 :]
-            deferredResult = authority.BindAuthority._lookup(self, name, cls,
-                                                             dns.NS, timeout)
-        return deferredResult
+        try:
+            result = yield authority.BindAuthority._lookup(self, name, cls,
+                                                           type, timeout)
+            defer.returnValue(result)
+        except Exception as e:
+            # XXX: Twisted returns DomainError even if it is
+            # authoritative for the domain because our SOA record
+            # incorrectly contains (origin + "." + origin)
+            if not isinstance(e, (dns.DomainError, dns.AuthoritativeDomainError)):
+                sys.stderr.write("while looking up '%s', got: %s\n" % (name, e))
+
+            # If we didn't find an exact match for the name we were
+            # seeking, check if it's within a subdomain we're supposed
+            # to delegate to some other DNS server.
+            while '.' in name:
+                _, name = name.split('.', 1)
+                try:
+                    # BindAuthority puts the NS in the authority
+                    # section automatically for us, so just return
+                    # it. We override the type to NS.
+                    result = yield authority.BindAuthority._lookup(self, name, cls,
+                                                                   dns.NS, timeout)
+                    defer.returnValue(result)
+                except Exception: # Should be one of (dns.DomainError, dns.AuthoritativeDomainError)
+                    pass
+            # We didn't find a delegation, so return the original
+            # NXDOMAIN.
+            raise
 
 class TypeLenientResolverChain(resolve.ResolverChain):
     """
@@ -256,6 +274,9 @@ if '__main__' == __name__:
                 r = DelegatingQuotingBindAuthority(zone)
                 # This sucks, but if I want a generic zone file, I have to
                 # reload the information by hand
+                # XXX: This causes our SOA record to contain
+                # (origin + "." + origin)
+                # As a result the resolver never believes it is authoritative.
                 r.origin = origin
                 lines = open(zone).readlines()
                 lines = r.collapseContinuations(r.stripComments(lines))