# 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 base64 import contextlib import enum import errno import os import random import selectors import socket import struct import time import urllib.parse from typing import Any, Callable, Dict, Optional, Tuple, cast import dns._features import dns._tls_util import dns.exception import dns.inet import dns.message import dns.name import dns.quic import dns.rdata import dns.rdataclass import dns.rdatatype import dns.transaction import dns.tsig import dns.xfr try: import ssl except ImportError: import dns._no_ssl as ssl # type: ignore def _remaining(expiration): if expiration is None: return None timeout = expiration - time.time() if timeout <= 0.0: raise dns.exception.Timeout return timeout def _expiration_for_this_attempt(timeout, expiration): if expiration is None: return None return min(time.time() + timeout, expiration) _have_httpx = dns._features.have("doh") if _have_httpx: import httpcore._backends.sync import httpx _CoreNetworkBackend = httpcore.NetworkBackend _CoreSyncStream = httpcore._backends.sync.SyncStream class _NetworkBackend(_CoreNetworkBackend): def __init__(self, resolver, local_port, bootstrap_address, family): super().__init__() self._local_port = local_port self._resolver = resolver self._bootstrap_address = bootstrap_address self._family = family def connect_tcp( self, host, port, timeout=None, local_address=None, socket_options=None ): # pylint: disable=signature-differs addresses = [] _, expiration = _compute_times(timeout) if dns.inet.is_address(host): addresses.append(host) elif self._bootstrap_address is not None: addresses.append(self._bootstrap_address) else: timeout = _remaining(expiration) family = self._family if local_address: family = dns.inet.af_for_address(local_address) answers = self._resolver.resolve_name( host, family=family, lifetime=timeout ) addresses = answers.addresses() for address in addresses: af = dns.inet.af_for_address(address) if local_address is not None or self._local_port != 0: if local_address is None: local_address = "0.0.0.0" source = dns.inet.low_level_address_tuple( (local_address, self._local_port), af ) else: source = None try: sock = make_socket(af, socket.SOCK_STREAM, source) attempt_expiration = _expiration_for_this_attempt(2.0, expiration) _connect( sock, dns.inet.low_level_address_tuple((address, port), af), attempt_expiration, ) return _CoreSyncStream(sock) except Exception: pass raise httpcore.ConnectError def connect_unix_socket( self, path, timeout=None, socket_options=None ): # pylint: disable=signature-differs raise NotImplementedError class _HTTPTransport(httpx.HTTPTransport): # pyright: ignore def __init__( self, *args, local_port=0, bootstrap_address=None, resolver=None, family=socket.AF_UNSPEC, **kwargs, ): if resolver is None and bootstrap_address is None: # pylint: disable=import-outside-toplevel,redefined-outer-name import dns.resolver resolver = dns.resolver.Resolver() super().__init__(*args, **kwargs) self._pool._network_backend = _NetworkBackend( resolver, local_port, bootstrap_address, family ) else: class _HTTPTransport: # type: ignore def __init__( self, *args, local_port=0, bootstrap_address=None, resolver=None, family=socket.AF_UNSPEC, **kwargs, ): pass def connect_tcp(self, host, port, timeout, local_address): raise NotImplementedError have_doh = _have_httpx def default_socket_factory( af: socket.AddressFamily | int, kind: socket.SocketKind, proto: int, ) -> socket.socket: return socket.socket(af, kind, proto) # Function used to create a socket. Can be overridden if needed in special # situations. socket_factory: Callable[ [socket.AddressFamily | int, socket.SocketKind, int], socket.socket ] = default_socket_factory class UnexpectedSource(dns.exception.DNSException): """A DNS query response came from an unexpected address or port.""" class BadResponse(dns.exception.FormError): """A DNS query response does not respond to the question asked.""" class NoDOH(dns.exception.DNSException): """DNS over HTTPS (DOH) was requested but the httpx module is not available.""" class NoDOQ(dns.exception.DNSException): """DNS over QUIC (DOQ) was requested but the aioquic module is not available.""" # for backwards compatibility TransferError = dns.xfr.TransferError def _compute_times(timeout): now = time.time() if timeout is None: return (now, None) else: return (now, now + timeout) def _wait_for(fd, readable, writable, _, expiration): # Use the selected selector class to wait for any of the specified # events. An "expiration" absolute time is converted into a relative # timeout. # # The unused parameter is 'error', which is always set when # selecting for read or write, and we have no error-only selects. if readable and isinstance(fd, ssl.SSLSocket) and fd.pending() > 0: return True with selectors.DefaultSelector() as sel: events = 0 if readable: events |= selectors.EVENT_READ if writable: events |= selectors.EVENT_WRITE if events: sel.register(fd, events) # pyright: ignore if expiration is None: timeout = None else: timeout = expiration - time.time() if timeout <= 0.0: raise dns.exception.Timeout if not sel.select(timeout): raise dns.exception.Timeout 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 try: n1 = dns.inet.inet_pton(af, a1[0]) n2 = dns.inet.inet_pton(af, a2[0]) except dns.exception.SyntaxError: return False return n1 == n2 and a1[1:] == a2[1:] def _matches_destination(af, from_address, destination, ignore_unexpected): # Check that from_address is appropriate for a response to a query # sent to destination. if not destination: return True if _addresses_equal(af, from_address, destination) or ( dns.inet.is_multicast(destination[0]) and from_address[1:] == destination[1:] ): return True elif ignore_unexpected: return False raise UnexpectedSource( f"got a response from {from_address} instead of " f"{destination}" ) def _destination_and_source( where, port, source, source_port, where_must_be_address=True ): # Apply defaults and compute destination and source tuples # suitable for use in connect(), sendto(), or bind(). af = None destination = None try: af = dns.inet.af_for_address(where) destination = where except Exception: if where_must_be_address: raise # URLs are ok so eat the exception if source: saf = dns.inet.af_for_address(source) if af: # We know the destination af, so source had better agree! if saf != af: raise ValueError( "different address families for source and destination" ) else: # We didn't know the destination af, but we know the source, # so that's our af. af = saf if source_port and not source: # Caller has specified a source_port but not an address, so we # need to return a source, and we need to use the appropriate # wildcard address as the address. try: source = dns.inet.any_for_af(af) except Exception: # we catch this and raise ValueError for backwards compatibility raise ValueError("source_port specified but address family is unknown") # Convert high-level (address, port) tuples into low-level address # tuples. if destination: destination = dns.inet.low_level_address_tuple((destination, port), af) if source: source = dns.inet.low_level_address_tuple((source, source_port), af) return (af, destination, source) def make_socket( af: socket.AddressFamily | int, type: socket.SocketKind, source: Any | None = None, ) -> socket.socket: """Make a socket. This function uses the module's ``socket_factory`` to make a socket of the specified address family and type. *af*, a ``socket.AddressFamily`` or ``int`` is the address family, either ``socket.AF_INET`` or ``socket.AF_INET6``. *type*, a ``socket.SocketKind`` is the type of socket, e.g. ``socket.SOCK_DGRAM``, a datagram socket, or ``socket.SOCK_STREAM``, a stream socket. Note that the ``proto`` attribute of a socket is always zero with this API, so a datagram socket will always be a UDP socket, and a stream socket will always be a TCP socket. *source* is the source address and port to bind to, if any. The default is ``None`` which will bind to the wildcard address and a randomly chosen port. If not ``None``, it should be a (low-level) address tuple appropriate for *af*. """ s = socket_factory(af, type, 0) try: s.setblocking(False) if source is not None: s.bind(source) return s except Exception: s.close() raise def make_ssl_socket( af: socket.AddressFamily | int, type: socket.SocketKind, ssl_context: ssl.SSLContext, server_hostname: dns.name.Name | str | None = None, source: Any | None = None, ) -> ssl.SSLSocket: """Make a socket. This function uses the module's ``socket_factory`` to make a socket of the specified address family and type. *af*, a ``socket.AddressFamily`` or ``int`` is the address family, either ``socket.AF_INET`` or ``socket.AF_INET6``. *type*, a ``socket.SocketKind`` is the type of socket, e.g. ``socket.SOCK_DGRAM``, a datagram socket, or ``socket.SOCK_STREAM``, a stream socket. Note that the ``proto`` attribute of a socket is always zero with this API, so a datagram socket will always be a UDP socket, and a stream socket will always be a TCP socket. If *ssl_context* is not ``None``, then it specifies the SSL context to use, typically created with ``make_ssl_context()``. If *server_hostname* is not ``None``, then it is the hostname to use for server certificate validation. A valid hostname must be supplied if *ssl_context* requires hostname checking. *source* is the source address and port to bind to, if any. The default is ``None`` which will bind to the wildcard address and a randomly chosen port. If not ``None``, it should be a (low-level) address tuple appropriate for *af*. """ sock = make_socket(af, type, source) if isinstance(server_hostname, dns.name.Name): server_hostname = server_hostname.to_text() # LGTM gets a false positive here, as our default context is OK return ssl_context.wrap_socket( sock, do_handshake_on_connect=False, # lgtm[py/insecure-protocol] server_hostname=server_hostname, ) # for backwards compatibility def _make_socket( af, type, source, ssl_context, server_hostname, ): if ssl_context is not None: return make_ssl_socket(af, type, ssl_context, server_hostname, source) else: return make_socket(af, type, source) def _maybe_get_resolver( resolver: Optional["dns.resolver.Resolver"], # pyright: ignore ) -> "dns.resolver.Resolver": # pyright: ignore # We need a separate method for this to avoid overriding the global # variable "dns" with the as-yet undefined local variable "dns" # in https(). if resolver is None: # pylint: disable=import-outside-toplevel,redefined-outer-name import dns.resolver resolver = dns.resolver.Resolver() return resolver class HTTPVersion(enum.IntEnum): """Which version of HTTP should be used? DEFAULT will select the first version from the list [2, 1.1, 3] that is available. """ DEFAULT = 0 HTTP_1 = 1 H1 = 1 HTTP_2 = 2 H2 = 2 HTTP_3 = 3 H3 = 3 def https( q: dns.message.Message, where: str, timeout: float | None = None, port: int = 443, source: str | None = None, source_port: int = 0, one_rr_per_rrset: bool = False, ignore_trailing: bool = False, session: Any | None = None, path: str = "/dns-query", post: bool = True, bootstrap_address: str | None = None, verify: bool | str | ssl.SSLContext = True, resolver: Optional["dns.resolver.Resolver"] = None, # pyright: ignore family: int = socket.AF_UNSPEC, http_version: HTTPVersion = HTTPVersion.DEFAULT, ) -> dns.message.Message: """Return the response obtained after sending a query via DNS-over-HTTPS. *q*, a ``dns.message.Message``, the query to send. *where*, a ``str``, the nameserver IP address or the full URL. If an IP address is given, the URL will be constructed using the following schema: https://:/. *timeout*, a ``float`` or ``None``, the number of seconds to wait before the query times out. If ``None``, the default, wait forever. *port*, a ``int``, the port to send the query to. The default is 443. *source*, a ``str`` containing an IPv4 or IPv6 address, specifying the source address. The default is the wildcard address. *source_port*, an ``int``, the port from which to send the message. The default is 0. *one_rr_per_rrset*, a ``bool``. If ``True``, put each RR into its own RRset. *ignore_trailing*, a ``bool``. If ``True``, ignore trailing junk at end of the received message. *session*, an ``httpx.Client``. If provided, the client session to use to send the queries. *path*, a ``str``. If *where* is an IP address, then *path* will be used to construct the URL to send the DNS query to. *post*, a ``bool``. If ``True``, the default, POST method will be used. *bootstrap_address*, a ``str``, the IP address to use to bypass resolution. *verify*, a ``bool`` or ``str``. If a ``True``, then TLS certificate verification of the server is done using the default CA bundle; if ``False``, then no verification is done; if a `str` then it specifies the path to a certificate file or directory which will be used for verification. *resolver*, a ``dns.resolver.Resolver`` or ``None``, the resolver to use for resolution of hostnames in URLs. If not specified, a new resolver with a default configuration will be used; note this is *not* the default resolver as that resolver might have been configured to use DoH causing a chicken-and-egg problem. This parameter only has an effect if the HTTP library is httpx. *family*, an ``int``, the address family. If socket.AF_UNSPEC (the default), both A and AAAA records will be retrieved. *http_version*, a ``dns.query.HTTPVersion``, indicating which HTTP version to use. Returns a ``dns.message.Message``. """ (af, _, the_source) = _destination_and_source( where, port, source, source_port, False ) # we bind url and then override as pyright can't figure out all paths bind. url = where if af is not None and dns.inet.is_address(where): if af == socket.AF_INET: url = f"https://{where}:{port}{path}" elif af == socket.AF_INET6: url = f"https://[{where}]:{port}{path}" extensions = {} if bootstrap_address is None: # pylint: disable=possibly-used-before-assignment parsed = urllib.parse.urlparse(url) if parsed.hostname is None: raise ValueError("no hostname in URL") if dns.inet.is_address(parsed.hostname): bootstrap_address = parsed.hostname extensions["sni_hostname"] = parsed.hostname if parsed.port is not None: port = parsed.port if http_version == HTTPVersion.H3 or ( http_version == HTTPVersion.DEFAULT and not have_doh ): if bootstrap_address is None: resolver = _maybe_get_resolver(resolver) assert parsed.hostname is not None # pyright: ignore answers = resolver.resolve_name(parsed.hostname, family) # pyright: ignore bootstrap_address = random.choice(list(answers.addresses())) if session and not isinstance( session, dns.quic.SyncQuicConnection ): # pyright: ignore raise ValueError("session parameter must be a dns.quic.SyncQuicConnection.") return _http3( q, bootstrap_address, url, # pyright: ignore timeout, port, source, source_port, one_rr_per_rrset, ignore_trailing, verify=verify, post=post, connection=session, ) if not have_doh: raise NoDOH # pragma: no cover if session and not isinstance(session, httpx.Client): # pyright: ignore raise ValueError("session parameter must be an httpx.Client") wire = q.to_wire() headers = {"accept": "application/dns-message"} h1 = http_version in (HTTPVersion.H1, HTTPVersion.DEFAULT) h2 = http_version in (HTTPVersion.H2, HTTPVersion.DEFAULT) # set source port and source address if the_source is None: local_address = None local_port = 0 else: local_address = the_source[0] local_port = the_source[1] if session: cm: contextlib.AbstractContextManager = contextlib.nullcontext(session) else: transport = _HTTPTransport( local_address=local_address, http1=h1, http2=h2, verify=verify, local_port=local_port, bootstrap_address=bootstrap_address, resolver=resolver, family=family, # pyright: ignore ) cm = httpx.Client( # type: ignore http1=h1, http2=h2, verify=verify, transport=transport # type: ignore ) with cm as session: # see https://tools.ietf.org/html/rfc8484#section-4.1.1 for DoH # GET and POST examples assert session is not None if post: headers.update( { "content-type": "application/dns-message", "content-length": str(len(wire)), } ) response = session.post( url, headers=headers, content=wire, timeout=timeout, extensions=extensions, ) else: wire = base64.urlsafe_b64encode(wire).rstrip(b"=") twire = wire.decode() # httpx does a repr() if we give it bytes response = session.get( url, headers=headers, timeout=timeout, params={"dns": twire}, extensions=extensions, ) # see https://tools.ietf.org/html/rfc8484#section-4.2.1 for info about DoH # status codes if response.status_code < 200 or response.status_code > 299: raise ValueError( f"{where} responded with status code {response.status_code}" f"\nResponse body: {response.content}" ) r = dns.message.from_wire( response.content, keyring=q.keyring, request_mac=q.request_mac, one_rr_per_rrset=one_rr_per_rrset, ignore_trailing=ignore_trailing, ) r.time = response.elapsed.total_seconds() if not q.is_response(r): raise BadResponse return r def _find_header(headers: dns.quic.Headers, name: bytes) -> bytes: if headers is None: raise KeyError for header, value in headers: if header == name: return value raise KeyError def _check_status(headers: dns.quic.Headers, peer: str, wire: bytes) -> None: value = _find_header(headers, b":status") if value is None: raise SyntaxError("no :status header in response") status = int(value) if status < 0: raise SyntaxError("status is negative") if status < 200 or status > 299: error = "" if len(wire) > 0: try: error = ": " + wire.decode() except Exception: pass raise ValueError(f"{peer} responded with status code {status}{error}") def _http3( q: dns.message.Message, where: str, url: str, timeout: float | None = None, port: int = 443, source: str | None = None, source_port: int = 0, one_rr_per_rrset: bool = False, ignore_trailing: bool = False, verify: bool | str | ssl.SSLContext = True, post: bool = True, connection: dns.quic.SyncQuicConnection | None = None, ) -> dns.message.Message: if not dns.quic.have_quic: raise NoDOH("DNS-over-HTTP3 is not available.") # pragma: no cover url_parts = urllib.parse.urlparse(url) hostname = url_parts.hostname assert hostname is not None if url_parts.port is not None: port = url_parts.port q.id = 0 wire = q.to_wire() the_connection: dns.quic.SyncQuicConnection the_manager: dns.quic.SyncQuicManager if connection: manager: contextlib.AbstractContextManager = contextlib.nullcontext(None) else: manager = dns.quic.SyncQuicManager( verify_mode=verify, server_name=hostname, h3=True # pyright: ignore ) the_manager = manager # for type checking happiness with manager: if connection: the_connection = connection else: the_connection = the_manager.connect( # pyright: ignore where, port, source, source_port ) (start, expiration) = _compute_times(timeout) with the_connection.make_stream(timeout) as stream: # pyright: ignore stream.send_h3(url, wire, post) wire = stream.receive(_remaining(expiration)) _check_status(stream.headers(), where, wire) finish = time.time() r = dns.message.from_wire( wire, keyring=q.keyring, request_mac=q.request_mac, one_rr_per_rrset=one_rr_per_rrset, ignore_trailing=ignore_trailing, ) r.time = max(finish - start, 0.0) if not q.is_response(r): raise BadResponse return r def _udp_recv(sock, max_size, expiration): """Reads a datagram from the socket. A Timeout exception will be raised if the operation is not completed by the expiration time. """ while True: try: return sock.recvfrom(max_size) except BlockingIOError: _wait_for_readable(sock, expiration) def _udp_send(sock, data, destination, expiration): """Sends the specified datagram to destination over the socket. A Timeout exception will be raised if the operation is not completed by the expiration time. """ while True: try: if destination: return sock.sendto(data, destination) else: return sock.send(data) except BlockingIOError: # pragma: no cover _wait_for_writable(sock, expiration) def send_udp( sock: Any, what: dns.message.Message | bytes, destination: Any, expiration: float | None = None, ) -> Tuple[int, float]: """Send a DNS message to the specified UDP socket. *sock*, a ``socket``. *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 = _udp_send(sock, what, destination, expiration) return (n, sent_time) def receive_udp( sock: Any, destination: Any | None = None, expiration: float | None = None, ignore_unexpected: bool = False, one_rr_per_rrset: bool = False, keyring: Dict[dns.name.Name, dns.tsig.Key] | None = None, request_mac: bytes | None = b"", ignore_trailing: bool = False, raise_on_truncation: bool = False, ignore_errors: bool = False, query: dns.message.Message | None = None, ) -> Any: """Read a DNS message from a UDP socket. *sock*, a ``socket``. *destination*, a destination tuple appropriate for the address family of the socket, specifying where the message is expected to arrive from. When receiving a response, this would be where the associated query was sent. *expiration*, a ``float`` or ``None``, the absolute time at which a timeout exception should be raised. If ``None``, no timeout will occur. *ignore_unexpected*, a ``bool``. If ``True``, ignore responses from unexpected sources. *one_rr_per_rrset*, a ``bool``. If ``True``, put each RR into its own RRset. *keyring*, a ``dict``, the keyring to use for TSIG. *request_mac*, a ``bytes`` or ``None``, the MAC of the request (for TSIG). *ignore_trailing*, a ``bool``. If ``True``, ignore trailing junk at end of the received message. *raise_on_truncation*, a ``bool``. If ``True``, raise an exception if the TC bit is set. Raises if the message is malformed, if network errors occur, of if there is a timeout. If *destination* is not ``None``, returns a ``(dns.message.Message, float)`` tuple of the received message and the received time. If *destination* is ``None``, returns a ``(dns.message.Message, float, tuple)`` tuple of the received message, the received time, and the address where the message arrived from. *ignore_errors*, a ``bool``. If various format errors or response mismatches occur, ignore them and keep listening for a valid response. The default is ``False``. *query*, a ``dns.message.Message`` or ``None``. If not ``None`` and *ignore_errors* is ``True``, check that the received message is a response to this query, and if not keep listening for a valid response. """ wire = b"" while True: (wire, from_address) = _udp_recv(sock, 65535, expiration) if not _matches_destination( sock.family, from_address, destination, ignore_unexpected ): continue received_time = time.time() try: 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, ) except dns.message.Truncated as e: # If we got Truncated and not FORMERR, we at least got the header with TC # set, and very likely the question section, so we'll re-raise if the # message seems to be a response as we need to know when truncation happens. # We need to check that it seems to be a response as we don't want a random # injected message with TC set to cause us to bail out. if ( ignore_errors and query is not None and not query.is_response(e.message()) ): continue else: raise except Exception: if ignore_errors: continue else: raise if ignore_errors and query is not None and not query.is_response(r): continue if destination: return (r, received_time) else: return (r, received_time, from_address) def udp( q: dns.message.Message, where: str, timeout: float | None = None, port: int = 53, source: str | None = None, source_port: int = 0, ignore_unexpected: bool = False, one_rr_per_rrset: bool = False, ignore_trailing: bool = False, raise_on_truncation: bool = False, sock: Any | None = None, ignore_errors: bool = False, ) -> dns.message.Message: """Return the response obtained after sending a query via UDP. *q*, a ``dns.message.Message``, the query to send *where*, a ``str`` containing an IPv4 or IPv6 address, where to send the message. *timeout*, a ``float`` or ``None``, the number of seconds to wait before the query times out. If ``None``, the default, wait forever. *port*, an ``int``, the port send the message to. The default is 53. *source*, a ``str`` containing an IPv4 or IPv6 address, specifying the source address. The default is the wildcard address. *source_port*, an ``int``, the port from which to send the message. The default is 0. *ignore_unexpected*, a ``bool``. If ``True``, ignore responses from unexpected sources. *one_rr_per_rrset*, a ``bool``. If ``True``, put each RR into its own RRset. *ignore_trailing*, a ``bool``. If ``True``, ignore trailing junk at end of the received message. *raise_on_truncation*, a ``bool``. If ``True``, raise an exception if the TC bit is set. *sock*, a ``socket.socket``, 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 nonblocking datagram socket, and the *source* and *source_port* are ignored. *ignore_errors*, a ``bool``. If various format errors or response mismatches occur, ignore them and keep listening for a valid response. The default is ``False``. Returns a ``dns.message.Message``. """ wire = q.to_wire() (af, destination, source) = _destination_and_source( where, port, source, source_port, True ) (begin_time, expiration) = _compute_times(timeout) if sock: cm: contextlib.AbstractContextManager = contextlib.nullcontext(sock) else: assert af is not None cm = make_socket(af, socket.SOCK_DGRAM, source) with cm as s: send_udp(s, wire, destination, expiration) (r, received_time) = receive_udp( s, destination, expiration, ignore_unexpected, one_rr_per_rrset, q.keyring, q.mac, ignore_trailing, raise_on_truncation, ignore_errors, q, ) r.time = received_time - begin_time # We don't need to check q.is_response() if we are in ignore_errors mode # as receive_udp() will have checked it. if not (ignore_errors or q.is_response(r)): raise BadResponse return r assert ( False # help mypy figure out we can't get here lgtm[py/unreachable-statement] ) def udp_with_fallback( q: dns.message.Message, where: str, timeout: float | None = None, port: int = 53, source: str | None = None, source_port: int = 0, ignore_unexpected: bool = False, one_rr_per_rrset: bool = False, ignore_trailing: bool = False, udp_sock: Any | None = None, tcp_sock: Any | None = None, ignore_errors: bool = False, ) -> Tuple[dns.message.Message, bool]: """Return the response to the query, trying UDP first and falling back to TCP if UDP results in a truncated response. *q*, a ``dns.message.Message``, the query to send *where*, a ``str`` containing an IPv4 or IPv6 address, where to send the message. *timeout*, a ``float`` or ``None``, the number of seconds to wait before the query times out. If ``None``, the default, wait forever. *port*, an ``int``, the port send the message to. The default is 53. *source*, a ``str`` containing an IPv4 or IPv6 address, specifying the source address. The default is the wildcard address. *source_port*, an ``int``, the port from which to send the message. The default is 0. *ignore_unexpected*, a ``bool``. If ``True``, ignore responses from unexpected sources. *one_rr_per_rrset*, a ``bool``. If ``True``, put each RR into its own RRset. *ignore_trailing*, a ``bool``. If ``True``, ignore trailing junk at end of the received message. *udp_sock*, a ``socket.socket``, 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, it must be a nonblocking datagram socket, and the *source* and *source_port* are ignored for the UDP query. *tcp_sock*, a ``socket.socket``, or ``None``, the connected socket to use for the TCP query. If ``None``, the default, a socket is created. Note that if a socket is provided, it must be a nonblocking connected stream socket, and *where*, *source* and *source_port* are ignored for the TCP query. *ignore_errors*, a ``bool``. If various format errors or response mismatches occur while listening for UDP, ignore them and keep listening for a valid response. The default is ``False``. Returns a (``dns.message.Message``, tcp) tuple where tcp is ``True`` if and only if TCP was used. """ try: response = udp( q, where, timeout, port, source, source_port, ignore_unexpected, one_rr_per_rrset, ignore_trailing, True, udp_sock, ignore_errors, ) return (response, False) except dns.message.Truncated: response = tcp( q, where, timeout, port, source, source_port, one_rr_per_rrset, ignore_trailing, tcp_sock, ) return (response, True) 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 = b"" while count > 0: try: n = sock.recv(count) if n == b"": raise EOFError("EOF") count -= len(n) s += n except (BlockingIOError, ssl.SSLWantReadError): _wait_for_readable(sock, expiration) except ssl.SSLWantWriteError: # pragma: no cover _wait_for_writable(sock, expiration) 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: try: current += sock.send(data[current:]) except (BlockingIOError, ssl.SSLWantWriteError): _wait_for_writable(sock, expiration) except ssl.SSLWantReadError: # pragma: no cover _wait_for_readable(sock, expiration) def send_tcp( sock: Any, what: dns.message.Message | bytes, expiration: float | None = None, ) -> Tuple[int, float]: """Send a DNS message to the specified TCP socket. *sock*, a ``socket``. *what*, a ``bytes`` or ``dns.message.Message``, the message to send. *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): tcpmsg = what.to_wire(prepend_length=True) else: # 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 = len(what).to_bytes(2, "big") + what sent_time = time.time() _net_write(sock, tcpmsg, expiration) return (len(tcpmsg), sent_time) def receive_tcp( sock: Any, expiration: float | None = None, one_rr_per_rrset: bool = False, keyring: Dict[dns.name.Name, dns.tsig.Key] | None = None, request_mac: bytes | None = b"", ignore_trailing: bool = False, ) -> Tuple[dns.message.Message, float]: """Read a DNS message from a TCP socket. *sock*, a ``socket``. *expiration*, a ``float`` or ``None``, the absolute time at which a timeout exception should be raised. If ``None``, no timeout will occur. *one_rr_per_rrset*, a ``bool``. If ``True``, put each RR into its own RRset. *keyring*, a ``dict``, the keyring to use for TSIG. *request_mac*, a ``bytes`` or ``None``, the MAC of the request (for TSIG). *ignore_trailing*, a ``bool``. If ``True``, ignore trailing junk at end of the received message. Raises if the message is malformed, if network errors occur, of if there is a timeout. Returns a ``(dns.message.Message, float)`` tuple of the received message and the received time. """ ldata = _net_read(sock, 2, expiration) (l,) = struct.unpack("!H", ldata) wire = _net_read(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) def _connect(s, address, expiration): err = s.connect_ex(address) if err == 0: return if err in (errno.EINPROGRESS, errno.EWOULDBLOCK, errno.EALREADY): _wait_for_writable(s, expiration) err = s.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR) if err != 0: raise OSError(err, os.strerror(err)) def tcp( q: dns.message.Message, where: str, timeout: float | None = None, port: int = 53, source: str | None = None, source_port: int = 0, one_rr_per_rrset: bool = False, ignore_trailing: bool = False, sock: Any | None = None, ) -> dns.message.Message: """Return the response obtained after sending a query via TCP. *q*, a ``dns.message.Message``, the query to send *where*, a ``str`` containing an IPv4 or IPv6 address, where to send the message. *timeout*, a ``float`` or ``None``, the number of seconds to wait before the query times out. If ``None``, the default, wait forever. *port*, an ``int``, the port send the message to. The default is 53. *source*, a ``str`` containing an IPv4 or IPv6 address, specifying the source address. The default is the wildcard address. *source_port*, an ``int``, the port from which to send the message. The default is 0. *one_rr_per_rrset*, a ``bool``. If ``True``, put each RR into its own RRset. *ignore_trailing*, a ``bool``. If ``True``, ignore trailing junk at end of the received message. *sock*, a ``socket.socket``, or ``None``, the connected 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 nonblocking connected stream socket, and *where*, *port*, *source* and *source_port* are ignored. Returns a ``dns.message.Message``. """ wire = q.to_wire() (begin_time, expiration) = _compute_times(timeout) if sock: cm: contextlib.AbstractContextManager = contextlib.nullcontext(sock) else: (af, destination, source) = _destination_and_source( where, port, source, source_port, True ) assert af is not None cm = make_socket(af, socket.SOCK_STREAM, source) with cm as s: if not sock: # pylint: disable=possibly-used-before-assignment _connect(s, destination, expiration) # pyright: ignore send_tcp(s, wire, expiration) (r, received_time) = 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 assert ( False # help mypy figure out we can't get here lgtm[py/unreachable-statement] ) def _tls_handshake(s, expiration): while True: try: s.do_handshake() return except ssl.SSLWantReadError: _wait_for_readable(s, expiration) except ssl.SSLWantWriteError: # pragma: no cover _wait_for_writable(s, expiration) def make_ssl_context( verify: bool | str = True, check_hostname: bool = True, alpns: list[str] | None = None, ) -> ssl.SSLContext: """Make an SSL context If *verify* is ``True``, the default, then certificate verification will occur using the standard CA roots. If *verify* is ``False``, then certificate verification will be disabled. If *verify* is a string which is a valid pathname, then if the pathname is a regular file, the CA roots will be taken from the file, otherwise if the pathname is a directory roots will be taken from the directory. If *check_hostname* is ``True``, the default, then the hostname of the server must be specified when connecting and the server's certificate must authorize the hostname. If ``False``, then hostname checking is disabled. *aplns* is ``None`` or a list of TLS ALPN (Application Layer Protocol Negotiation) strings to use in negotiation. For DNS-over-TLS, the right value is `["dot"]`. """ cafile, capath = dns._tls_util.convert_verify_to_cafile_and_capath(verify) ssl_context = ssl.create_default_context(cafile=cafile, capath=capath) # the pyright ignores below are because it gets confused between the # _no_ssl compatibility types and the real ones. ssl_context.minimum_version = ssl.TLSVersion.TLSv1_2 # type: ignore ssl_context.check_hostname = check_hostname if verify is False: ssl_context.verify_mode = ssl.CERT_NONE # type: ignore if alpns is not None: ssl_context.set_alpn_protocols(alpns) return ssl_context # type: ignore # for backwards compatibility def _make_dot_ssl_context( server_hostname: str | None, verify: bool | str ) -> ssl.SSLContext: return make_ssl_context(verify, server_hostname is not None, ["dot"]) def tls( q: dns.message.Message, where: str, timeout: float | None = None, port: int = 853, source: str | None = None, source_port: int = 0, one_rr_per_rrset: bool = False, ignore_trailing: bool = False, sock: ssl.SSLSocket | None = None, ssl_context: ssl.SSLContext | None = None, server_hostname: str | None = None, verify: bool | str = True, ) -> dns.message.Message: """Return the response obtained after sending a query via TLS. *q*, a ``dns.message.Message``, the query to send *where*, a ``str`` containing an IPv4 or IPv6 address, where to send the message. *timeout*, a ``float`` or ``None``, the number of seconds to wait before the query times out. If ``None``, the default, wait forever. *port*, an ``int``, the port send the message to. The default is 853. *source*, a ``str`` containing an IPv4 or IPv6 address, specifying the source address. The default is the wildcard address. *source_port*, an ``int``, the port from which to send the message. The default is 0. *one_rr_per_rrset*, a ``bool``. If ``True``, put each RR into its own RRset. *ignore_trailing*, a ``bool``. If ``True``, ignore trailing junk at end of the received message. *sock*, an ``ssl.SSLSocket``, 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 nonblocking connected SSL stream socket, and *where*, *port*, *source*, *source_port*, and *ssl_context* are ignored. *ssl_context*, an ``ssl.SSLContext``, the context to use when establishing a TLS connection. If ``None``, the default, creates one with the default configuration. *server_hostname*, a ``str`` containing the server's hostname. The default is ``None``, which means that no hostname is known, and if an SSL context is created, hostname checking will be disabled. *verify*, a ``bool`` or ``str``. If a ``True``, then TLS certificate verification of the server is done using the default CA bundle; if ``False``, then no verification is done; if a `str` then it specifies the path to a certificate file or directory which will be used for verification. Returns a ``dns.message.Message``. """ if sock: # # If a socket was provided, there's no special TLS handling needed. # return tcp( q, where, timeout, port, source, source_port, one_rr_per_rrset, ignore_trailing, sock, ) wire = q.to_wire() (begin_time, expiration) = _compute_times(timeout) (af, destination, source) = _destination_and_source( where, port, source, source_port, True ) assert af is not None # where must be an address if ssl_context is None: ssl_context = make_ssl_context(verify, server_hostname is not None, ["dot"]) with make_ssl_socket( af, socket.SOCK_STREAM, ssl_context=ssl_context, server_hostname=server_hostname, source=source, ) as s: _connect(s, destination, expiration) _tls_handshake(s, expiration) send_tcp(s, wire, expiration) (r, received_time) = 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 assert ( False # help mypy figure out we can't get here lgtm[py/unreachable-statement] ) def quic( q: dns.message.Message, where: str, timeout: float | None = None, port: int = 853, source: str | None = None, source_port: int = 0, one_rr_per_rrset: bool = False, ignore_trailing: bool = False, connection: dns.quic.SyncQuicConnection | None = None, verify: bool | str = True, hostname: str | None = None, server_hostname: str | None = None, ) -> dns.message.Message: """Return the response obtained after sending a query via DNS-over-QUIC. *q*, a ``dns.message.Message``, the query to send. *where*, a ``str``, the nameserver IP address. *timeout*, a ``float`` or ``None``, the number of seconds to wait before the query times out. If ``None``, the default, wait forever. *port*, a ``int``, the port to send the query to. The default is 853. *source*, a ``str`` containing an IPv4 or IPv6 address, specifying the source address. The default is the wildcard address. *source_port*, an ``int``, the port from which to send the message. The default is 0. *one_rr_per_rrset*, a ``bool``. If ``True``, put each RR into its own RRset. *ignore_trailing*, a ``bool``. If ``True``, ignore trailing junk at end of the received message. *connection*, a ``dns.quic.SyncQuicConnection``. If provided, the connection to use to send the query. *verify*, a ``bool`` or ``str``. If a ``True``, then TLS certificate verification of the server is done using the default CA bundle; if ``False``, then no verification is done; if a `str` then it specifies the path to a certificate file or directory which will be used for verification. *hostname*, a ``str`` containing the server's hostname or ``None``. The default is ``None``, which means that no hostname is known, and if an SSL context is created, hostname checking will be disabled. This value is ignored if *url* is not ``None``. *server_hostname*, a ``str`` or ``None``. This item is for backwards compatibility only, and has the same meaning as *hostname*. Returns a ``dns.message.Message``. """ if not dns.quic.have_quic: raise NoDOQ("DNS-over-QUIC is not available.") # pragma: no cover if server_hostname is not None and hostname is None: hostname = server_hostname q.id = 0 wire = q.to_wire() the_connection: dns.quic.SyncQuicConnection the_manager: dns.quic.SyncQuicManager if connection: manager: contextlib.AbstractContextManager = contextlib.nullcontext(None) the_connection = connection else: manager = dns.quic.SyncQuicManager( verify_mode=verify, server_name=hostname # pyright: ignore ) the_manager = manager # for type checking happiness with manager: if not connection: the_connection = the_manager.connect( # pyright: ignore where, port, source, source_port ) (start, expiration) = _compute_times(timeout) with the_connection.make_stream(timeout) as stream: # pyright: ignore stream.send(wire, True) wire = stream.receive(_remaining(expiration)) finish = time.time() r = dns.message.from_wire( wire, keyring=q.keyring, request_mac=q.request_mac, one_rr_per_rrset=one_rr_per_rrset, ignore_trailing=ignore_trailing, ) r.time = max(finish - start, 0.0) if not q.is_response(r): raise BadResponse return r class UDPMode(enum.IntEnum): """How should UDP be used in an IXFR from :py:func:`inbound_xfr()`? NEVER means "never use UDP; always use TCP" TRY_FIRST means "try to use UDP but fall back to TCP if needed" ONLY means "raise ``dns.xfr.UseTCP`` if trying UDP does not succeed" """ NEVER = 0 TRY_FIRST = 1 ONLY = 2 def _inbound_xfr( txn_manager: dns.transaction.TransactionManager, s: socket.socket | ssl.SSLSocket, query: dns.message.Message, serial: int | None, timeout: float | None, expiration: float | None, ) -> Any: """Given a socket, does the zone transfer.""" rdtype = query.question[0].rdtype is_ixfr = rdtype == dns.rdatatype.IXFR origin = txn_manager.from_wire_origin() wire = query.to_wire() is_udp = isinstance(s, socket.socket) and s.type == socket.SOCK_DGRAM if is_udp: _udp_send(s, wire, None, expiration) else: tcpmsg = struct.pack("!H", len(wire)) + wire _net_write(s, tcpmsg, expiration) with dns.xfr.Inbound(txn_manager, rdtype, serial, is_udp) as inbound: done = False tsig_ctx = None r: dns.message.Message | None = 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: (rwire, _) = _udp_recv(s, 65535, mexpiration) else: ldata = _net_read(s, 2, mexpiration) (l,) = struct.unpack("!H", ldata) rwire = _net_read(s, l, mexpiration) 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, ) done = inbound.process_message(r) yield r tsig_ctx = r.tsig_ctx if query.keyring and r is not None and not r.had_tsig: raise dns.exception.FormError("missing TSIG") def xfr( where: str, zone: dns.name.Name | str, rdtype: dns.rdatatype.RdataType | str = dns.rdatatype.AXFR, rdclass: dns.rdataclass.RdataClass | str = dns.rdataclass.IN, timeout: float | None = None, port: int = 53, keyring: Dict[dns.name.Name, dns.tsig.Key] | None = None, keyname: dns.name.Name | str | None = None, relativize: bool = True, lifetime: float | None = None, source: str | None = None, source_port: int = 0, serial: int = 0, use_udp: bool = False, keyalgorithm: dns.name.Name | str = dns.tsig.default_algorithm, ) -> Any: """Return a generator for the responses to a zone transfer. *where*, a ``str`` containing an IPv4 or IPv6 address, where to send the message. *zone*, a ``dns.name.Name`` or ``str``, the name of the zone to transfer. *rdtype*, an ``int`` or ``str``, the type of zone transfer. The default is ``dns.rdatatype.AXFR``. ``dns.rdatatype.IXFR`` can be used to do an incremental transfer instead. *rdclass*, an ``int`` or ``str``, the class of the zone transfer. The default is ``dns.rdataclass.IN``. *timeout*, a ``float``, the number of seconds to wait for each response message. If None, the default, wait forever. *port*, an ``int``, the port send the message to. The default is 53. *keyring*, a ``dict``, the keyring to use for TSIG. *keyname*, a ``dns.name.Name`` or ``str``, the name of the TSIG key to use. *relativize*, a ``bool``. 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()`` if using this generator to make a zone. *lifetime*, a ``float``, 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. *source*, a ``str`` containing an IPv4 or IPv6 address, specifying the source address. The default is the wildcard address. *source_port*, an ``int``, the port from which to send the message. The default is 0. *serial*, an ``int``, the SOA serial number to use as the base for an IXFR diff sequence (only meaningful if *rdtype* is ``dns.rdatatype.IXFR``). *use_udp*, a ``bool``. If ``True``, use UDP (only meaningful for IXFR). *keyalgorithm*, a ``dns.name.Name`` or ``str``, the TSIG algorithm to use. Raises on errors, and so does the generator. Returns a generator of ``dns.message.Message`` objects. """ class DummyTransactionManager(dns.transaction.TransactionManager): def __init__(self, origin, relativize): self.info = (origin, relativize, dns.name.empty if relativize else origin) def origin_information(self): return self.info def get_class(self) -> dns.rdataclass.RdataClass: raise NotImplementedError # pragma: no cover def reader(self): raise NotImplementedError # pragma: no cover def writer(self, replacement: bool = False) -> dns.transaction.Transaction: class DummyTransaction: def nop(self, *args, **kw): pass def __getattr__(self, _): return self.nop return cast(dns.transaction.Transaction, DummyTransaction()) if isinstance(zone, str): zone = dns.name.from_text(zone) rdtype = dns.rdatatype.RdataType.make(rdtype) q = dns.message.make_query(zone, rdtype, rdclass) if rdtype == dns.rdatatype.IXFR: rrset = q.find_rrset( q.authority, zone, dns.rdataclass.IN, dns.rdatatype.SOA, create=True ) soa = dns.rdata.from_text("IN", "SOA", f". . {serial} 0 0 0 0") rrset.add(soa, 0) if keyring is not None: q.use_tsig(keyring, keyname, algorithm=keyalgorithm) (af, destination, source) = _destination_and_source( where, port, source, source_port, True ) assert af is not None (_, expiration) = _compute_times(lifetime) tm = DummyTransactionManager(zone, relativize) if use_udp and rdtype != dns.rdatatype.IXFR: raise ValueError("cannot do a UDP AXFR") sock_type = socket.SOCK_DGRAM if use_udp else socket.SOCK_STREAM with make_socket(af, sock_type, source) as s: _connect(s, destination, expiration) yield from _inbound_xfr(tm, s, q, serial, timeout, expiration) def inbound_xfr( where: str, txn_manager: dns.transaction.TransactionManager, query: dns.message.Message | None = None, port: int = 53, timeout: float | None = None, lifetime: float | None = None, source: str | None = None, source_port: int = 0, udp_mode: UDPMode = UDPMode.NEVER, ) -> None: """Conduct an inbound transfer and apply it via a transaction from the txn_manager. *where*, a ``str`` containing an IPv4 or IPv6 address, where to send the message. *txn_manager*, a ``dns.transaction.TransactionManager``, the txn_manager for this transfer (typically a ``dns.zone.Zone``). *query*, the query to send. If not supplied, a default query is constructed using information from the *txn_manager*. *port*, an ``int``, the port send the message to. The default is 53. *timeout*, a ``float``, the number of seconds to wait for each response message. If None, the default, wait forever. *lifetime*, a ``float``, 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. *source*, a ``str`` containing an IPv4 or IPv6 address, specifying the source address. The default is the wildcard address. *source_port*, an ``int``, the port from which to send the message. The default is 0. *udp_mode*, a ``dns.query.UDPMode``, determines how UDP is used for IXFRs. The default is ``dns.query.UDPMode.NEVER``, i.e. only use TCP. Other possibilities are ``dns.query.UDPMode.TRY_FIRST``, which means "try UDP but fallback to TCP if needed", and ``dns.query.UDPMode.ONLY``, which means "try UDP and raise ``dns.xfr.UseTCP`` if it does not succeed. Raises on errors. """ if query is None: (query, serial) = dns.xfr.make_query(txn_manager) else: serial = dns.xfr.extract_serial_from_query(query) (af, destination, source) = _destination_and_source( where, port, source, source_port, True ) assert af is not None (_, expiration) = _compute_times(lifetime) if query.question[0].rdtype == dns.rdatatype.IXFR and udp_mode != UDPMode.NEVER: with make_socket(af, socket.SOCK_DGRAM, source) as s: _connect(s, destination, expiration) try: for _ in _inbound_xfr( txn_manager, s, query, serial, timeout, expiration ): pass return except dns.xfr.UseTCP: if udp_mode == UDPMode.ONLY: raise with make_socket(af, socket.SOCK_STREAM, source) as s: _connect(s, destination, expiration) for _ in _inbound_xfr(txn_manager, s, query, serial, timeout, expiration): pass