Bump dnspython from 2.3.0 to 2.4.2 (#2123)

* Bump dnspython from 2.3.0 to 2.4.2

Bumps [dnspython](https://github.com/rthalley/dnspython) from 2.3.0 to 2.4.2.
- [Release notes](https://github.com/rthalley/dnspython/releases)
- [Changelog](https://github.com/rthalley/dnspython/blob/master/doc/whatsnew.rst)
- [Commits](https://github.com/rthalley/dnspython/compare/v2.3.0...v2.4.2)

---
updated-dependencies:
- dependency-name: dnspython
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

* Update dnspython==2.4.2

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: JonnyWong16 <9099342+JonnyWong16@users.noreply.github.com>

[skip ci]

lib/dns/_trio_backend.py

@@ -3,6 +3,7 @@
 """trio async I/O library query support"""
 
 import socket
+
 import trio
 import trio.socket  # type: ignore
 
@@ -12,7 +13,7 @@ import dns.inet
 
 
 def _maybe_timeout(timeout):
-    if timeout:
+    if timeout is not None:
         return trio.move_on_after(timeout)
     else:
         return dns._asyncbackend.NullContext()
@@ -50,6 +51,9 @@ class DatagramSocket(dns._asyncbackend.DatagramSocket):
     async def getsockname(self):
         return self.socket.getsockname()
 
+    async def getpeercert(self, timeout):
+        raise NotImplementedError
+
 
 class StreamSocket(dns._asyncbackend.StreamSocket):
     def __init__(self, family, stream, tls=False):
@@ -82,6 +86,100 @@ class StreamSocket(dns._asyncbackend.StreamSocket):
         else:
             return self.stream.socket.getsockname()
 
+    async def getpeercert(self, timeout):
+        if self.tls:
+            with _maybe_timeout(timeout):
+                await self.stream.do_handshake()
+            return self.stream.getpeercert()
+        else:
+            raise NotImplementedError
+
+
+try:
+    import httpcore
+    import httpcore._backends.trio
+    import httpx
+
+    _CoreAsyncNetworkBackend = httpcore.AsyncNetworkBackend
+    _CoreTrioStream = httpcore._backends.trio.TrioStream
+
+    from dns.query import _compute_times, _expiration_for_this_attempt, _remaining
+
+    class _NetworkBackend(_CoreAsyncNetworkBackend):
+        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
+
+        async def connect_tcp(
+            self, host, port, timeout, local_address, 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 = await self._resolver.resolve_name(
+                    host, family=family, lifetime=timeout
+                )
+                addresses = answers.addresses()
+            for address in addresses:
+                try:
+                    af = dns.inet.af_for_address(address)
+                    if local_address is not None or self._local_port != 0:
+                        source = (local_address, self._local_port)
+                    else:
+                        source = None
+                    destination = (address, port)
+                    attempt_expiration = _expiration_for_this_attempt(2.0, expiration)
+                    timeout = _remaining(attempt_expiration)
+                    sock = await Backend().make_socket(
+                        af, socket.SOCK_STREAM, 0, source, destination, timeout
+                    )
+                    return _CoreTrioStream(sock.stream)
+                except Exception:
+                    continue
+            raise httpcore.ConnectError
+
+        async def connect_unix_socket(
+            self, path, timeout, socket_options=None
+        ):  # pylint: disable=signature-differs
+            raise NotImplementedError
+
+        async def sleep(self, seconds):  # pylint: disable=signature-differs
+            await trio.sleep(seconds)
+
+    class _HTTPTransport(httpx.AsyncHTTPTransport):
+        def __init__(
+            self,
+            *args,
+            local_port=0,
+            bootstrap_address=None,
+            resolver=None,
+            family=socket.AF_UNSPEC,
+            **kwargs,
+        ):
+            if resolver is None:
+                # pylint: disable=import-outside-toplevel,redefined-outer-name
+                import dns.asyncresolver
+
+                resolver = dns.asyncresolver.Resolver()
+            super().__init__(*args, **kwargs)
+            self._pool._network_backend = _NetworkBackend(
+                resolver, local_port, bootstrap_address, family
+            )
+
+except ImportError:
+    _HTTPTransport = dns._asyncbackend.NullTransport  # type: ignore
+
 
 class Backend(dns._asyncbackend.Backend):
     def name(self):
@@ -104,8 +202,14 @@ class Backend(dns._asyncbackend.Backend):
             if source:
                 await s.bind(_lltuple(source, af))
             if socktype == socket.SOCK_STREAM:
+                connected = False
                 with _maybe_timeout(timeout):
                     await s.connect(_lltuple(destination, af))
+                    connected = True
+                if not connected:
+                    raise dns.exception.Timeout(
+                        timeout=timeout
+                    )  # lgtm[py/unreachable-statement]
         except Exception:  # pragma: no cover
             s.close()
             raise
@@ -130,3 +234,13 @@ class Backend(dns._asyncbackend.Backend):
 
     async def sleep(self, interval):
         await trio.sleep(interval)
+
+    def get_transport_class(self):
+        return _HTTPTransport
+
+    async def wait_for(self, awaitable, timeout):
+        with _maybe_timeout(timeout):
+            return await awaitable
+        raise dns.exception.Timeout(
+            timeout=timeout
+        )  # pragma: no cover  lgtm[py/unreachable-statement]