diff options
Diffstat (limited to 'third_party/dnspython/dns/query.py')
| -rw-r--r-- | third_party/dnspython/dns/query.py | 492 |
1 files changed, 492 insertions, 0 deletions
diff --git a/third_party/dnspython/dns/query.py b/third_party/dnspython/dns/query.py new file mode 100644 index 0000000000..addee4e3f2 --- /dev/null +++ b/third_party/dnspython/dns/query.py @@ -0,0 +1,492 @@ +# Copyright (C) 2003-2007, 2009-2011 Nominum, Inc. +# +# Permission to use, copy, modify, and distribute this software and its +# documentation for any purpose with or without fee is hereby granted, +# provided that the above copyright notice and this permission notice +# appear in all copies. +# +# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES +# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF +# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR +# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES +# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN +# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT +# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + +"""Talk to a DNS server.""" + +from __future__ import generators + +import errno +import select +import socket +import struct +import sys +import time + +import dns.exception +import dns.inet +import dns.name +import dns.message +import dns.rdataclass +import dns.rdatatype + +class UnexpectedSource(dns.exception.DNSException): + """Raised if a query response comes from an unexpected address or port.""" + pass + +class BadResponse(dns.exception.FormError): + """Raised if a query response does not respond to the question asked.""" + pass + +def _compute_expiration(timeout): + if timeout is None: + return None + else: + return time.time() + timeout + +def _poll_for(fd, readable, writable, error, timeout): + """ + @param fd: File descriptor (int). + @param readable: Whether to wait for readability (bool). + @param writable: Whether to wait for writability (bool). + @param expiration: Deadline timeout (expiration time, in seconds (float)). + + @return True on success, False on timeout + """ + event_mask = 0 + if readable: + event_mask |= select.POLLIN + if writable: + event_mask |= select.POLLOUT + if error: + event_mask |= select.POLLERR + + pollable = select.poll() + pollable.register(fd, event_mask) + + if timeout: + event_list = pollable.poll(long(timeout * 1000)) + else: + event_list = pollable.poll() + + return bool(event_list) + +def _select_for(fd, readable, writable, error, timeout): + """ + @param fd: File descriptor (int). + @param readable: Whether to wait for readability (bool). + @param writable: Whether to wait for writability (bool). + @param expiration: Deadline timeout (expiration time, in seconds (float)). + + @return True on success, False on timeout + """ + rset, wset, xset = [], [], [] + + if readable: + rset = [fd] + if writable: + wset = [fd] + if error: + xset = [fd] + + if timeout is None: + (rcount, wcount, xcount) = select.select(rset, wset, xset) + else: + (rcount, wcount, xcount) = select.select(rset, wset, xset, timeout) + + return bool((rcount or wcount or xcount)) + +def _wait_for(fd, readable, writable, error, expiration): + done = False + while not done: + if expiration is None: + timeout = None + else: + timeout = expiration - time.time() + if timeout <= 0.0: + raise dns.exception.Timeout + try: + if not _polling_backend(fd, readable, writable, error, timeout): + raise dns.exception.Timeout + except select.error, e: + if e.args[0] != errno.EINTR: + raise e + done = True + +def _set_polling_backend(fn): + """ + Internal API. Do not use. + """ + global _polling_backend + + _polling_backend = fn + +if hasattr(select, 'poll'): + # Prefer poll() on platforms that support it because it has no + # limits on the maximum value of a file descriptor (plus it will + # be more efficient for high values). + _polling_backend = _poll_for +else: + _polling_backend = _select_for + +def _wait_for_readable(s, expiration): + _wait_for(s, True, False, True, expiration) + +def _wait_for_writable(s, expiration): + _wait_for(s, False, True, True, expiration) + +def _addresses_equal(af, a1, a2): + # Convert the first value of the tuple, which is a textual format + # address into binary form, so that we are not confused by different + # textual representations of the same address + n1 = dns.inet.inet_pton(af, a1[0]) + n2 = dns.inet.inet_pton(af, a2[0]) + return n1 == n2 and a1[1:] == a2[1:] + +def udp(q, where, timeout=None, port=53, af=None, source=None, source_port=0, + ignore_unexpected=False, one_rr_per_rrset=False): + """Return the response obtained after sending a query via UDP. + + @param q: the query + @type q: dns.message.Message + @param where: where to send the message + @type where: string containing an IPv4 or IPv6 address + @param timeout: The number of seconds to wait before the query times out. + If None, the default, wait forever. + @type timeout: float + @param port: The port to which to send the message. The default is 53. + @type port: int + @param af: the address family to use. The default is None, which + causes the address family to use to be inferred from the form of of where. + If the inference attempt fails, AF_INET is used. + @type af: int + @rtype: dns.message.Message object + @param source: source address. The default is the IPv4 wildcard address. + @type source: string + @param source_port: The port from which to send the message. + The default is 0. + @type source_port: int + @param ignore_unexpected: If True, ignore responses from unexpected + sources. The default is False. + @type ignore_unexpected: bool + @param one_rr_per_rrset: Put each RR into its own RRset + @type one_rr_per_rrset: bool + """ + + wire = q.to_wire() + if af is None: + try: + af = dns.inet.af_for_address(where) + except: + af = dns.inet.AF_INET + if af == dns.inet.AF_INET: + destination = (where, port) + if source is not None: + source = (source, source_port) + elif af == dns.inet.AF_INET6: + destination = (where, port, 0, 0) + if source is not None: + source = (source, source_port, 0, 0) + s = socket.socket(af, socket.SOCK_DGRAM, 0) + try: + expiration = _compute_expiration(timeout) + s.setblocking(0) + if source is not None: + s.bind(source) + _wait_for_writable(s, expiration) + s.sendto(wire, destination) + while 1: + _wait_for_readable(s, expiration) + (wire, from_address) = s.recvfrom(65535) + if _addresses_equal(af, from_address, destination) or \ + (dns.inet.is_multicast(where) and \ + from_address[1:] == destination[1:]): + break + if not ignore_unexpected: + raise UnexpectedSource('got a response from ' + '%s instead of %s' % (from_address, + destination)) + finally: + s.close() + r = dns.message.from_wire(wire, keyring=q.keyring, request_mac=q.mac, + one_rr_per_rrset=one_rr_per_rrset) + if not q.is_response(r): + raise BadResponse + return r + +def _net_read(sock, count, expiration): + """Read the specified number of bytes from sock. Keep trying until we + either get the desired amount, or we hit EOF. + A Timeout exception will be raised if the operation is not completed + by the expiration time. + """ + s = '' + while count > 0: + _wait_for_readable(sock, expiration) + n = sock.recv(count) + if n == '': + raise EOFError + count = count - len(n) + s = s + n + return s + +def _net_write(sock, data, expiration): + """Write the specified data to the socket. + A Timeout exception will be raised if the operation is not completed + by the expiration time. + """ + current = 0 + l = len(data) + while current < l: + _wait_for_writable(sock, expiration) + current += sock.send(data[current:]) + +def _connect(s, address): + try: + s.connect(address) + except socket.error: + (ty, v) = sys.exc_info()[:2] + if v[0] != errno.EINPROGRESS and \ + v[0] != errno.EWOULDBLOCK and \ + v[0] != errno.EALREADY: + raise v + +def tcp(q, where, timeout=None, port=53, af=None, source=None, source_port=0, + one_rr_per_rrset=False): + """Return the response obtained after sending a query via TCP. + + @param q: the query + @type q: dns.message.Message object + @param where: where to send the message + @type where: string containing an IPv4 or IPv6 address + @param timeout: The number of seconds to wait before the query times out. + If None, the default, wait forever. + @type timeout: float + @param port: The port to which to send the message. The default is 53. + @type port: int + @param af: the address family to use. The default is None, which + causes the address family to use to be inferred from the form of of where. + If the inference attempt fails, AF_INET is used. + @type af: int + @rtype: dns.message.Message object + @param source: source address. The default is the IPv4 wildcard address. + @type source: string + @param source_port: The port from which to send the message. + The default is 0. + @type source_port: int + @param one_rr_per_rrset: Put each RR into its own RRset + @type one_rr_per_rrset: bool + """ + + wire = q.to_wire() + if af is None: + try: + af = dns.inet.af_for_address(where) + except: + af = dns.inet.AF_INET + if af == dns.inet.AF_INET: + destination = (where, port) + if source is not None: + source = (source, source_port) + elif af == dns.inet.AF_INET6: + destination = (where, port, 0, 0) + if source is not None: + source = (source, source_port, 0, 0) + s = socket.socket(af, socket.SOCK_STREAM, 0) + try: + expiration = _compute_expiration(timeout) + s.setblocking(0) + if source is not None: + s.bind(source) + _connect(s, destination) + + l = len(wire) + + # copying the wire into tcpmsg is inefficient, but lets us + # avoid writev() or doing a short write that would get pushed + # onto the net + tcpmsg = struct.pack("!H", l) + wire + _net_write(s, tcpmsg, expiration) + ldata = _net_read(s, 2, expiration) + (l,) = struct.unpack("!H", ldata) + wire = _net_read(s, l, expiration) + finally: + s.close() + r = dns.message.from_wire(wire, keyring=q.keyring, request_mac=q.mac, + one_rr_per_rrset=one_rr_per_rrset) + if not q.is_response(r): + raise BadResponse + return r + +def xfr(where, zone, rdtype=dns.rdatatype.AXFR, rdclass=dns.rdataclass.IN, + timeout=None, port=53, keyring=None, keyname=None, relativize=True, + af=None, lifetime=None, source=None, source_port=0, serial=0, + use_udp=False, keyalgorithm=dns.tsig.default_algorithm): + """Return a generator for the responses to a zone transfer. + + @param where: where to send the message + @type where: string containing an IPv4 or IPv6 address + @param zone: The name of the zone to transfer + @type zone: dns.name.Name object or string + @param rdtype: The type of zone transfer. The default is + dns.rdatatype.AXFR. + @type rdtype: int or string + @param rdclass: The class of the zone transfer. The default is + dns.rdatatype.IN. + @type rdclass: int or string + @param timeout: The number of seconds to wait for each response message. + If None, the default, wait forever. + @type timeout: float + @param port: The port to which to send the message. The default is 53. + @type port: int + @param keyring: The TSIG keyring to use + @type keyring: dict + @param keyname: The name of the TSIG key to use + @type keyname: dns.name.Name object or string + @param relativize: If True, all names in the zone will be relativized to + the zone origin. It is essential that the relativize setting matches + the one specified to dns.zone.from_xfr(). + @type relativize: bool + @param af: the address family to use. The default is None, which + causes the address family to use to be inferred from the form of of where. + If the inference attempt fails, AF_INET is used. + @type af: int + @param lifetime: The total number of seconds to spend doing the transfer. + If None, the default, then there is no limit on the time the transfer may + take. + @type lifetime: float + @rtype: generator of dns.message.Message objects. + @param source: source address. The default is the IPv4 wildcard address. + @type source: string + @param source_port: The port from which to send the message. + The default is 0. + @type source_port: int + @param serial: The SOA serial number to use as the base for an IXFR diff + sequence (only meaningful if rdtype == dns.rdatatype.IXFR). + @type serial: int + @param use_udp: Use UDP (only meaningful for IXFR) + @type use_udp: bool + @param keyalgorithm: The TSIG algorithm to use; defaults to + dns.tsig.default_algorithm + @type keyalgorithm: string + """ + + if isinstance(zone, (str, unicode)): + zone = dns.name.from_text(zone) + if isinstance(rdtype, (str, unicode)): + rdtype = dns.rdatatype.from_text(rdtype) + q = dns.message.make_query(zone, rdtype, rdclass) + if rdtype == dns.rdatatype.IXFR: + rrset = dns.rrset.from_text(zone, 0, 'IN', 'SOA', + '. . %u 0 0 0 0' % serial) + q.authority.append(rrset) + if not keyring is None: + q.use_tsig(keyring, keyname, algorithm=keyalgorithm) + wire = q.to_wire() + if af is None: + try: + af = dns.inet.af_for_address(where) + except: + af = dns.inet.AF_INET + if af == dns.inet.AF_INET: + destination = (where, port) + if source is not None: + source = (source, source_port) + elif af == dns.inet.AF_INET6: + destination = (where, port, 0, 0) + if source is not None: + source = (source, source_port, 0, 0) + if use_udp: + if rdtype != dns.rdatatype.IXFR: + raise ValueError('cannot do a UDP AXFR') + s = socket.socket(af, socket.SOCK_DGRAM, 0) + else: + s = socket.socket(af, socket.SOCK_STREAM, 0) + s.setblocking(0) + if source is not None: + s.bind(source) + expiration = _compute_expiration(lifetime) + _connect(s, destination) + l = len(wire) + if use_udp: + _wait_for_writable(s, expiration) + s.send(wire) + else: + tcpmsg = struct.pack("!H", l) + wire + _net_write(s, tcpmsg, expiration) + done = False + soa_rrset = None + soa_count = 0 + if relativize: + origin = zone + oname = dns.name.empty + else: + origin = None + oname = zone + tsig_ctx = None + first = True + while not done: + mexpiration = _compute_expiration(timeout) + if mexpiration is None or mexpiration > expiration: + mexpiration = expiration + if use_udp: + _wait_for_readable(s, expiration) + (wire, from_address) = s.recvfrom(65535) + else: + ldata = _net_read(s, 2, mexpiration) + (l,) = struct.unpack("!H", ldata) + wire = _net_read(s, l, mexpiration) + r = dns.message.from_wire(wire, keyring=q.keyring, request_mac=q.mac, + xfr=True, origin=origin, tsig_ctx=tsig_ctx, + multi=True, first=first, + one_rr_per_rrset=(rdtype==dns.rdatatype.IXFR)) + tsig_ctx = r.tsig_ctx + first = False + answer_index = 0 + delete_mode = False + expecting_SOA = False + if soa_rrset is None: + if not r.answer or r.answer[0].name != oname: + raise dns.exception.FormError + rrset = r.answer[0] + if rrset.rdtype != dns.rdatatype.SOA: + raise dns.exception.FormError("first RRset is not an SOA") + answer_index = 1 + soa_rrset = rrset.copy() + if rdtype == dns.rdatatype.IXFR: + if soa_rrset[0].serial == serial: + # + # We're already up-to-date. + # + done = True + else: + expecting_SOA = True + # + # Process SOAs in the answer section (other than the initial + # SOA in the first message). + # + for rrset in r.answer[answer_index:]: + if done: + raise dns.exception.FormError("answers after final SOA") + if rrset.rdtype == dns.rdatatype.SOA and rrset.name == oname: + if expecting_SOA: + if rrset[0].serial != serial: + raise dns.exception.FormError("IXFR base serial mismatch") + expecting_SOA = False + elif rdtype == dns.rdatatype.IXFR: + delete_mode = not delete_mode + if rrset == soa_rrset and not delete_mode: + done = True + elif expecting_SOA: + # + # We made an IXFR request and are expecting another + # SOA RR, but saw something else, so this must be an + # AXFR response. + # + rdtype = dns.rdatatype.AXFR + expecting_SOA = False + if done and q.keyring and not r.had_tsig: + raise dns.exception.FormError("missing TSIG") + yield r + s.close() |