Add ".other" pseudo-subdomain to find IPs under transition.
[invirt/packages/invirt-dns.git] / invirt-dns
index d5fa021..7a39f0f 100755 (executable)
@@ -4,12 +4,14 @@ from twisted.names import server
 from twisted.names import dns
 from twisted.names import common
 from twisted.names import authority
+from twisted.names import resolve
 from twisted.internet import defer
 from twisted.python import failure
 
 from invirt.common import InvirtConfigError
 from invirt.config import structs as config
 import invirt.database
+from invirt.database import NIC
 import psycopg2
 import sqlalchemy
 import time
@@ -45,7 +47,7 @@ class DatabaseAuthority(common.ResolverBase):
         for i in range(3):
             try:
                 value = self._lookup_unsafe(name, cls, type, timeout = None)
-            except (psycopg2.OperationalError, sqlalchemy.exceptions.SQLError):
+            except (psycopg2.OperationalError, sqlalchemy.exceptions.DBAPIError):
                 if i == 2:
                     raise
                 print "Reloading database"
@@ -93,10 +95,12 @@ class DatabaseAuthority(common.ResolverBase):
         if name.endswith(".in-addr.arpa"):
             if type in (dns.PTR, dns.ALL_RECORDS):
                 ip = '.'.join(reversed(name.split('.')[:-2]))
-                value = invirt.database.NIC.query.filter_by(ip=ip).first()
+                value = invirt.database.NIC.query.filter((NIC.ip == ip) | (NIC.other_ip == ip)).first()
                 if value and value.hostname:
                     hostname = value.hostname
                     if '.' not in hostname:
+                        if ip == value.other_ip:
+                            hostname = hostname + ".other"
                         hostname = hostname + "." + config.dns.domains[0]
                     record = dns.Record_PTR(hostname, ttl)
                     results.append(dns.RRHeader(name, dns.PTR, dns.IN,
@@ -108,7 +112,7 @@ class DatabaseAuthority(common.ResolverBase):
                                             ttl, self.soa, auth=True))
             # FIXME: Should only return success with no records if the name actually exists
 
-        elif name == domain or name == '.'+domain:
+        elif name == domain or name == '.'+domain or name == 'other.'+domain:
             if type in (dns.A, dns.ALL_RECORDS):
                 record = dns.Record_A(config.dns.nameservers[0].ip, ttl)
                 results.append(dns.RRHeader(name, dns.A, dns.IN,
@@ -123,13 +127,23 @@ class DatabaseAuthority(common.ResolverBase):
 
         else:
             host = name[:-len(domain)-1]
+            other = False
+            if host.endswith(".other"):
+                host = host[:-len(".other")]
+                other = True
             value = invirt.database.NIC.query.filter_by(hostname=host).first()
             if value:
-                ip = value.ip
+                if other:
+                    ip = value.other_ip
+                else:
+                    ip = value.ip
             else:
-                value = invirt.database.Machine.query().filter_by(name=host).first()
+                value = invirt.database.Machine.query.filter_by(name=host).first()
                 if value:
-                    ip = value.nics[0].ip
+                    if other:
+                        ip = value.nics[0].other_ip
+                    else:
+                        ip = value.nics[0].ip
                 else:
                     return defer.fail(failure.Failure(dns.AuthoritativeDomainError(name)))
             if ip is None:
@@ -147,9 +161,9 @@ class DatabaseAuthority(common.ResolverBase):
             additional = []
         return defer.succeed((results, authority, additional))
 
-class QuotingBindAuthority(authority.BindAuthority):
+class DelegatingQuotingBindAuthority(authority.BindAuthority):
     """
-    A BindAuthority that (almost) deals with quoting correctly
+    A delegating BindAuthority that (almost) deals with quoting correctly
     
     This will catch double quotes as marking the start or end of a
     quoted phrase, unless the double quote is escaped by a backslash
@@ -194,12 +208,46 @@ class QuotingBindAuthority(authority.BindAuthority):
             L.append(split_line)
         return filter(None, L)
 
+    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
+
+class TypeLenientResolverChain(resolve.ResolverChain):
+    """
+    This is a ResolverChain which is more lenient in its handling of
+    queries requesting unimplemented record types.
+    """
+
+    def query(self, query, timeout = None):
+        try:
+            return self.typeToMethod[query.type](str(query.name), timeout)
+        except KeyError, e:
+            # We don't support the requested record type.  Twisted would
+            # have us return SERVFAIL.  Instead, we'll check whether the
+            # name exists in our zone at all and return NXDOMAIN or an empty
+            # result set with NOERROR as appropriate.
+            deferredResult = self.lookupAllRecords(str(query.name), timeout)
+            if isinstance(deferredResult.result, failure.Failure):
+                return deferredResult
+            return defer.succeed(([], [], []))
+
 if '__main__' == __name__:
     resolvers = []
     try:
         for zone in config.dns.zone_files:
             for origin in config.dns.domains:
-                r = QuotingBindAuthority(zone)
+                r = DelegatingQuotingBindAuthority(zone)
                 # This sucks, but if I want a generic zone file, I have to
                 # reload the information by hand
                 r.origin = origin
@@ -214,7 +262,8 @@ if '__main__' == __name__:
     resolvers.append(DatabaseAuthority())
 
     verbosity = 0
-    f = server.DNSServerFactory(authorities=resolvers, verbose=verbosity)
+    f = server.DNSServerFactory(verbose=verbosity)
+    f.resolver = TypeLenientResolverChain(resolvers)
     p = dns.DNSDatagramProtocol(f)
     f.noisy = p.noisy = verbosity