# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license # Copyright (C) 2003-2017 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.""" import socket import struct import time import dns.asyncbackend import dns.exception import dns.inet import dns.name import dns.message import dns.rcode import dns.rdataclass import dns.rdatatype from dns.query import _compute_times, _matches_destination, BadResponse, ssl, \ UDPMode # for brevity _lltuple = dns.inet.low_level_address_tuple def _source_tuple(af, address, port): # Make a high level source tuple, or return None if address and port # are both None if address or port: if address is None: if af == socket.AF_INET: address = '0.0.0.0' elif af == socket.AF_INET6: address = '::' else: raise NotImplementedError(f'unknown address family {af}') return (address, port) else: return None def _timeout(expiration, now=None): if expiration: if not now: now = time.time() return max(expiration - now, 0) else: return None async def send_udp(sock, what, destination, expiration=None): """Send a DNS message to the specified UDP socket. *sock*, a ``dns.asyncbackend.DatagramSocket``. *what*, a ``bytes`` or ``dns.message.Message``, the message to send. *destination*, a destination tuple appropriate for the address family of the socket, specifying where to send the query. *expiration*, a ``float`` or ``None``, the absolute time at which a timeout exception should be raised. If ``None``, no timeout will occur. Returns an ``(int, float)`` tuple of bytes sent and the sent time. """ if isinstance(what, dns.message.Message): what = what.to_wire() sent_time = time.time() n = await sock.sendto(what, destination, _timeout(expiration, sent_time)) return (n, sent_time) async def receive_udp(sock, destination=None, expiration=None, ignore_unexpected=False, one_rr_per_rrset=False, keyring=None, request_mac=b'', ignore_trailing=False, raise_on_truncation=False): """Read a DNS message from a UDP socket. *sock*, a ``dns.asyncbackend.DatagramSocket``. See :py:func:`dns.query.receive_udp()` for the documentation of the other parameters, exceptions, and return type of this method. """ wire = b'' while 1: (wire, from_address) = await sock.recvfrom(65535, _timeout(expiration)) if _matches_destination(sock.family, from_address, destination, ignore_unexpected): break received_time = time.time() r = dns.message.from_wire(wire, keyring=keyring, request_mac=request_mac, one_rr_per_rrset=one_rr_per_rrset, ignore_trailing=ignore_trailing, raise_on_truncation=raise_on_truncation) return (r, received_time, from_address) async def udp(q, where, timeout=None, port=53, source=None, source_port=0, ignore_unexpected=False, one_rr_per_rrset=False, ignore_trailing=False, raise_on_truncation=False, sock=None, backend=None): """Return the response obtained after sending a query via UDP. *sock*, a ``dns.asyncbackend.DatagramSocket``, or ``None``, the socket to use for the query. If ``None``, the default, a socket is created. Note that if a socket is provided, the *source*, *source_port*, and *backend* are ignored. *backend*, a ``dns.asyncbackend.Backend``, or ``None``. If ``None``, the default, then dnspython will use the default backend. See :py:func:`dns.query.udp()` for the documentation of the other parameters, exceptions, and return type of this method. """ wire = q.to_wire() (begin_time, expiration) = _compute_times(timeout) s = None # After 3.6 is no longer supported, this can use an AsyncExitStack. try: af = dns.inet.af_for_address(where) destination = _lltuple((where, port), af) if sock: s = sock else: if not backend: backend = dns.asyncbackend.get_default_backend() stuple = _source_tuple(af, source, source_port) if backend.datagram_connection_required(): dtuple = (where, port) else: dtuple = None s = await backend.make_socket(af, socket.SOCK_DGRAM, 0, stuple, dtuple) await send_udp(s, wire, destination, expiration) (r, received_time, _) = await receive_udp(s, destination, expiration, ignore_unexpected, one_rr_per_rrset, q.keyring, q.mac, ignore_trailing, raise_on_truncation) r.time = received_time - begin_time if not q.is_response(r): raise BadResponse return r finally: if not sock and s: await s.close() async def udp_with_fallback(q, where, timeout=None, port=53, source=None, source_port=0, ignore_unexpected=False, one_rr_per_rrset=False, ignore_trailing=False, udp_sock=None, tcp_sock=None, backend=None): """Return the response to the query, trying UDP first and falling back to TCP if UDP results in a truncated response. *udp_sock*, a ``dns.asyncbackend.DatagramSocket``, or ``None``, the socket to use for the UDP query. If ``None``, the default, a socket is created. Note that if a socket is provided the *source*, *source_port*, and *backend* are ignored for the UDP query. *tcp_sock*, a ``dns.asyncbackend.StreamSocket``, or ``None``, the socket to use for the TCP query. If ``None``, the default, a socket is created. Note that if a socket is provided *where*, *source*, *source_port*, and *backend* are ignored for the TCP query. *backend*, a ``dns.asyncbackend.Backend``, or ``None``. If ``None``, the default, then dnspython will use the default backend. See :py:func:`dns.query.udp_with_fallback()` for the documentation of the other parameters, exceptions, and return type of this method. """ try: response = await udp(q, where, timeout, port, source, source_port, ignore_unexpected, one_rr_per_rrset, ignore_trailing, True, udp_sock, backend) return (response, False) except dns.message.Truncated: response = await tcp(q, where, timeout, port, source, source_port, one_rr_per_rrset, ignore_trailing, tcp_sock, backend) return (response, True) async def send_tcp(sock, what, expiration=None): """Send a DNS message to the specified TCP socket. *sock*, a ``dns.asyncbackend.StreamSocket``. See :py:func:`dns.query.send_tcp()` for the documentation of the other parameters, exceptions, and return type of this method. """ if isinstance(what, dns.message.Message): what = what.to_wire() l = len(what) # 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) + what sent_time = time.time() await sock.sendall(tcpmsg, _timeout(expiration, sent_time)) return (len(tcpmsg), sent_time) async def _read_exactly(sock, count, expiration): """Read the specified number of bytes from stream. Keep trying until we either get the desired amount, or we hit EOF. """ s = b'' while count > 0: n = await sock.recv(count, _timeout(expiration)) if n == b'': raise EOFError count = count - len(n) s = s + n return s async def receive_tcp(sock, expiration=None, one_rr_per_rrset=False, keyring=None, request_mac=b'', ignore_trailing=False): """Read a DNS message from a TCP socket. *sock*, a ``dns.asyncbackend.StreamSocket``. See :py:func:`dns.query.receive_tcp()` for the documentation of the other parameters, exceptions, and return type of this method. """ ldata = await _read_exactly(sock, 2, expiration) (l,) = struct.unpack("!H", ldata) wire = await _read_exactly(sock, l, expiration) received_time = time.time() r = dns.message.from_wire(wire, keyring=keyring, request_mac=request_mac, one_rr_per_rrset=one_rr_per_rrset, ignore_trailing=ignore_trailing) return (r, received_time) async def tcp(q, where, timeout=None, port=53, source=None, source_port=0, one_rr_per_rrset=False, ignore_trailing=False, sock=None, backend=None): """Return the response obtained after sending a query via TCP. *sock*, a ``dns.asyncbacket.StreamSocket``, or ``None``, the socket to use for the query. If ``None``, the default, a socket is created. Note that if a socket is provided *where*, *port*, *source*, *source_port*, and *backend* are ignored. *backend*, a ``dns.asyncbackend.Backend``, or ``None``. If ``None``, the default, then dnspython will use the default backend. See :py:func:`dns.query.tcp()` for the documentation of the other parameters, exceptions, and return type of this method. """ wire = q.to_wire() (begin_time, expiration) = _compute_times(timeout) s = None # After 3.6 is no longer supported, this can use an AsyncExitStack. try: if sock: # Verify that the socket is connected, as if it's not connected, # it's not writable, and the polling in send_tcp() will time out or # hang forever. await sock.getpeername() s = sock else: # These are simple (address, port) pairs, not # family-dependent tuples you pass to lowlevel socket # code. af = dns.inet.af_for_address(where) stuple = _source_tuple(af, source, source_port) dtuple = (where, port) if not backend: backend = dns.asyncbackend.get_default_backend() s = await backend.make_socket(af, socket.SOCK_STREAM, 0, stuple, dtuple, timeout) await send_tcp(s, wire, expiration) (r, received_time) = await receive_tcp(s, expiration, one_rr_per_rrset, q.keyring, q.mac, ignore_trailing) r.time = received_time - begin_time if not q.is_response(r): raise BadResponse return r finally: if not sock and s: await s.close() async def tls(q, where, timeout=None, port=853, source=None, source_port=0, one_rr_per_rrset=False, ignore_trailing=False, sock=None, backend=None, ssl_context=None, server_hostname=None): """Return the response obtained after sending a query via TLS. *sock*, an ``asyncbackend.StreamSocket``, or ``None``, the socket to use for the query. If ``None``, the default, a socket is created. Note that if a socket is provided, it must be a connected SSL stream socket, and *where*, *port*, *source*, *source_port*, *backend*, *ssl_context*, and *server_hostname* are ignored. *backend*, a ``dns.asyncbackend.Backend``, or ``None``. If ``None``, the default, then dnspython will use the default backend. See :py:func:`dns.query.tls()` for the documentation of the other parameters, exceptions, and return type of this method. """ # After 3.6 is no longer supported, this can use an AsyncExitStack. (begin_time, expiration) = _compute_times(timeout) if not sock: if ssl_context is None: ssl_context = ssl.create_default_context() if server_hostname is None: ssl_context.check_hostname = False else: ssl_context = None server_hostname = None af = dns.inet.af_for_address(where) stuple = _source_tuple(af, source, source_port) dtuple = (where, port) if not backend: backend = dns.asyncbackend.get_default_backend() s = await backend.make_socket(af, socket.SOCK_STREAM, 0, stuple, dtuple, timeout, ssl_context, server_hostname) else: s = sock try: timeout = _timeout(expiration) response = await tcp(q, where, timeout, port, source, source_port, one_rr_per_rrset, ignore_trailing, s, backend) end_time = time.time() response.time = end_time - begin_time return response finally: if not sock and s: await s.close() async def inbound_xfr(where, txn_manager, query=None, port=53, timeout=None, lifetime=None, source=None, source_port=0, udp_mode=UDPMode.NEVER, backend=None): """Conduct an inbound transfer and apply it via a transaction from the txn_manager. *backend*, a ``dns.asyncbackend.Backend``, or ``None``. If ``None``, the default, then dnspython will use the default backend. See :py:func:`dns.query.inbound_xfr()` for the documentation of the other parameters, exceptions, and return type of this method. """ if query is None: (query, serial) = dns.xfr.make_query(txn_manager) rdtype = query.question[0].rdtype is_ixfr = rdtype == dns.rdatatype.IXFR origin = txn_manager.from_wire_origin() wire = query.to_wire() af = dns.inet.af_for_address(where) stuple = _source_tuple(af, source, source_port) dtuple = (where, port) (_, expiration) = _compute_times(lifetime) retry = True while retry: retry = False if is_ixfr and udp_mode != UDPMode.NEVER: sock_type = socket.SOCK_DGRAM is_udp = True else: sock_type = socket.SOCK_STREAM is_udp = False if not backend: backend = dns.asyncbackend.get_default_backend() s = await backend.make_socket(af, sock_type, 0, stuple, dtuple, _timeout(expiration)) async with s: if is_udp: await s.sendto(wire, dtuple, _timeout(expiration)) else: tcpmsg = struct.pack("!H", len(wire)) + wire await s.sendall(tcpmsg, expiration) with dns.xfr.Inbound(txn_manager, rdtype, serial, is_udp) as inbound: done = False tsig_ctx = None while not done: (_, mexpiration) = _compute_times(timeout) if mexpiration is None or \ (expiration is not None and mexpiration > expiration): mexpiration = expiration if is_udp: destination = _lltuple((where, port), af) while True: timeout = _timeout(mexpiration) (rwire, from_address) = await s.recvfrom(65535, timeout) if _matches_destination(af, from_address, destination, True): break else: ldata = await _read_exactly(s, 2, mexpiration) (l,) = struct.unpack("!H", ldata) rwire = await _read_exactly(s, l, mexpiration) is_ixfr = (rdtype == dns.rdatatype.IXFR) r = dns.message.from_wire(rwire, keyring=query.keyring, request_mac=query.mac, xfr=True, origin=origin, tsig_ctx=tsig_ctx, multi=(not is_udp), one_rr_per_rrset=is_ixfr) try: done = inbound.process_message(r) except dns.xfr.UseTCP: assert is_udp # should not happen if we used TCP! if udp_mode == UDPMode.ONLY: raise done = True retry = True udp_mode = UDPMode.NEVER continue tsig_ctx = r.tsig_ctx if not retry and query.keyring and not r.had_tsig: raise dns.exception.FormError("missing TSIG")