Workaround a bug in Twisted's zone file parsing.
[invirt/packages/invirt-dns.git] / invirt-dns
index e49c279..188d1ce 100755 (executable)
@@ -4,15 +4,19 @@ 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
 import re
+import sys
 
 class DatabaseAuthority(common.ResolverBase):
     """An Authority that is loaded from a file."""
@@ -44,7 +48,7 @@ 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"
@@ -62,14 +66,17 @@ class DatabaseAuthority(common.ResolverBase):
         if name in self.domains:
             domain = name
         else:
-            # Look for the longest-matching domain.  (This works because domain
-            # will remain bound after breaking out of the loop.)
+            # Look for the longest-matching domain.
             best_domain = ''
             for domain in self.domains:
                 if name.endswith('.'+domain) and len(domain) > len(best_domain):
                     best_domain = domain
             if best_domain == '':
-                return defer.fail(failure.Failure(dns.DomainError(name)))
+                if name.endswith('.in-addr.arpa'):
+                    # Act authoritative for the IP address for reverse resolution requests
+                    best_domain = name
+                else:
+                    return defer.fail(failure.Failure(dns.DomainError(name)))
             domain = best_domain
         results = []
         authority = []
@@ -77,46 +84,93 @@ class DatabaseAuthority(common.ResolverBase):
         authority.append(dns.RRHeader(domain, dns.NS, dns.IN,
                                       3600, self.ns, auth=True))
 
-        if cls == dns.IN:
-            host = name[:-len(domain)-1]
-            if not host: # Request for the domain itself.
-                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, 
+        # The order of logic:
+        # - What class?
+        # - What domain: in-addr.arpa, domain root, or subdomain?
+        # - What query type: A, PTR, NS, ...?
+
+        if cls != dns.IN:
+            # Hahaha.  No.
+            return defer.fail(failure.Failure(dns.AuthoritativeDomainError(name)))
+
+        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((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,
                                                 ttl, record, auth=True))
-                elif type == dns.NS:
-                    results.append(dns.RRHeader(domain, dns.NS, dns.IN,
-                                                ttl, self.ns, auth=True))
-                    authority = []
-                elif type == dns.SOA:
-                    results.append(dns.RRHeader(domain, dns.SOA, dns.IN,
-                                                ttl, self.soa, auth=True))
-            else: # Request for a subdomain.
-                value = invirt.database.Machine.query().filter_by(name=host).first()
-                if value is None or not value.nics:
-                    return defer.fail(failure.Failure(dns.AuthoritativeDomainError(name)))
-                ip = value.nics[0].ip
-                if ip is None:  #Deactivated?
+                else: # IP address doesn't point to an active host
                     return defer.fail(failure.Failure(dns.AuthoritativeDomainError(name)))
+            elif type == dns.SOA:
+                results.append(dns.RRHeader(domain, dns.SOA, dns.IN,
+                                            ttl, self.soa, auth=True))
+            # FIXME: Should only return success with no records if the name actually exists
 
-                if type in (dns.A, dns.ALL_RECORDS):
-                    record = dns.Record_A(ip, ttl)
-                    results.append(dns.RRHeader(name, dns.A, dns.IN, 
-                                                ttl, record, auth=True))
-                elif type == dns.SOA:
-                    results.append(dns.RRHeader(domain, dns.SOA, dns.IN,
-                                                ttl, self.soa, auth=True))
-            if len(results) == 0:
+        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,
+                                            ttl, record, auth=True))
+            elif type == dns.NS:
+                results.append(dns.RRHeader(domain, dns.NS, dns.IN,
+                                            ttl, self.ns, auth=True))
                 authority = []
-                additional = []
-            return defer.succeed((results, authority, additional))
+            elif type == dns.SOA:
+                results.append(dns.RRHeader(domain, dns.SOA, dns.IN,
+                                            ttl, self.soa, auth=True))
+
         else:
-            #Doesn't exist
-            return defer.fail(failure.Failure(dns.AuthoritativeDomainError(name)))
+            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:
+                if other:
+                    ip = value.other_ip
+                    action = value.other_action
+                else:
+                    ip = value.ip
+            else:
+                value = invirt.database.Machine.query.filter_by(name=host).first()
+                if value:
+                    if other:
+                        ip = value.nics[0].other_ip
+                        action = value.nics[0].other_action
+                    else:
+                        ip = value.nics[0].ip
+                else:
+                    return defer.fail(failure.Failure(dns.AuthoritativeDomainError(name)))
+            if ip is None:
+                return defer.fail(failure.Failure(dns.AuthoritativeDomainError(name)))
+            if type in (dns.A, dns.ALL_RECORDS):
+                record = dns.Record_A(ip, ttl)
+                results.append(dns.RRHeader(name, dns.A, dns.IN,
+                                            ttl, record, auth=True))
+            if other and type in (dns.TXT, dns.ALL_RECORDS):
+                record = dns.Record_TXT(action if action else '', ttl=ttl)
+                results.append(dns.RRHeader(name, dns.TXT, dns.IN,
+                                            ttl, record, auth=True))
+            if type == dns.SOA:
+                results.append(dns.RRHeader(domain, dns.SOA, dns.IN,
+                                            ttl, self.soa, auth=True))
 
-class QuotingBindAuthority(authority.BindAuthority):
+        if len(results) == 0:
+            authority = []
+            additional = []
+        return defer.succeed((results, authority, additional))
+
+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
@@ -161,23 +215,82 @@ class QuotingBindAuthority(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):
+        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):
+    """
+    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 = []
-    for zone in config.dns.zone_files:
-        for origin in config.dns.domains:
-            r = QuotingBindAuthority(zone)
-            # This sucks, but if I want a generic zone file, I have to
-            # reload the information by hand
-            r.origin = origin
-            lines = open(zone).readlines()
-            lines = r.collapseContinuations(r.stripComments(lines))
-            r.parseLines(lines)
-            
-            resolvers.append(r)
+    try:
+        for zone in config.dns.zone_files:
+            for origin in config.dns.domains:
+                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))
+                r.parseLines(lines)
+                
+                resolvers.append(r)
+    except InvirtConfigError:
+        # Don't care if zone_files isn't defined
+        pass
     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