1 files changed, 92 insertions, 0 deletions
diff --git a/dns/_curio_backend.py b/dns/_curio_backend.py
new file mode 100644
index 0000000..e37fea3
--- /dev/null
+++ b/dns/_curio_backend.py
@@ -0,0 +1,92 @@
+# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
+
+"""curio async I/O library query support"""
+
+import socket
+import curio
+import curio.socket  # type: ignore
+
+import dns._asyncbackend
+import dns.exception
+
+
+def _maybe_timeout(timeout):
+    if timeout:
+        return curio.ignore_after(timeout)
+    else:
+        return dns._asyncbackend.NullContext()
+
+
+# for brevity
+_lltuple = dns._asyncbackend.low_level_address_tuple
+
+
+class DatagramSocket(dns._asyncbackend.DatagramSocket):
+    def __init__(self, socket):
+        self.socket = socket
+        self.family = socket.family
+
+    async def sendto(self, what, destination, timeout):
+        async with _maybe_timeout(timeout):
+            return await self.socket.sendto(what, destination)
+        raise dns.exception.Timeout(timeout=timeout)
+
+    async def recvfrom(self, timeout):
+        async with _maybe_timeout(timeout):
+            return await self.socket.recvfrom(65535)
+        raise dns.exception.Timeout(timeout=timeout)
+
+    async def close(self):
+        await self.socket.close()
+
+    async def getpeername(self):
+        return self.socket.getpeername()
+
+
+class StreamSocket(dns._asyncbackend.DatagramSocket):
+    def __init__(self, socket):
+        self.socket = socket
+        self.family = socket.family
+
+    async def sendall(self, what, timeout):
+        async with _maybe_timeout(timeout):
+            return await self.socket.sendall(what)
+        raise dns.exception.Timeout(timeout=timeout)
+
+    async def recv(self, count, timeout):
+        async with _maybe_timeout(timeout):
+            return await self.socket.recv(count)
+        raise dns.exception.Timeout(timeout=timeout)
+
+    async def close(self):
+        await self.socket.close()
+
+    async def getpeername(self):
+        return self.socket.getpeername()
+
+
+class Backend(dns._asyncbackend.Backend):
+    def name(self):
+        return 'curio'
+
+    async def make_socket(self, af, socktype, proto=0,
+                          source=None, destination=None, timeout=None,
+                          ssl_context=None, server_hostname=None):
+        s = curio.socket.socket(af, socktype, proto)
+        try:
+            if source:
+                s.bind(_lltuple(af, source))
+            if socktype == socket.SOCK_STREAM:
+                with _maybe_timeout(timeout):
+                    await s.connect(_lltuple(af, destination))
+        except Exception:
+            await s.close()
+            raise
+        if socktype == socket.SOCK_DGRAM:
+            return DatagramSocket(s)
+        elif socktype == socket.SOCK_STREAM:
+            return StreamSocket(s)
+        raise NotImplementedError(f'unsupported socket type {socktype}')
+
+    async def sleep(self, interval):
+        await curio.sleep(interval)