aiocoap.transports.udp6 module

This module implements a MessageInterface for UDP based on a variation of the asyncio DatagramProtocol.

This implementation strives to be correct and complete behavior while still only using a single socket; that is, to be usable for all kinds of multicast traffic, to support server and client behavior at the same time, and to work correctly even when multiple IPv6 and IPv4 (using V4MAPPED addresses) interfaces are present, and any of the interfaces has multiple addresses.

This requires using a plethorea of standardized but not necessarily widely ported features: AI_V4MAPPED to support IPv4 without resorting to less standardized mechanisms for later options, IPV6_RECVPKTINFO to determine incoming packages’ destination addresses (was it multicast) and to return packages from the same address, IPV6_RECVERR to receive ICMP errors even on sockets that are not connected, IPV6_JOIN_GROUP for multicast membership management, and recvmsg and MSG_ERRQUEUE to obtain the data configured with the above options.

There are, if at all, only little attempts made to fall back to a kind-of-correct or limited-functionality behavior if these options are unavailable, for the resulting code would be hard to maintain (“ifdef hell”) or would cause odd bugs at users (eg. servers that stop working when an additional IPv6 address gets assigned). If the module does not work for you, and the options can not be added easily to your platform, consider using the simple6 module instead.

class aiocoap.transports.udp6.UDP6EndpointAddress(sockaddr, *, pktinfo=None)

Bases: aiocoap.interfaces.EndpointAddress

Remote address type for :cls:`MessageInterfaceUDP6`. Remote address is stored in form of a socket address; local address can be roundtripped by opaque pktinfo data.

>>> local = UDP6EndpointAddress(socket.getaddrinfo('', 5683, type=socket.SOCK_DGRAM, family=socket.AF_INET6, flags=socket.AI_V4MAPPED)[0][-1])
>>> local.is_multicast
>>> local.hostinfo
>>> all_coap_site = UDP6EndpointAddress(socket.getaddrinfo('ff05:0:0:0:0:0:0:fd', 1234, type=socket.SOCK_DGRAM, family=socket.AF_INET6)[0][-1])
>>> all_coap_site.is_multicast
>>> all_coap_site.hostinfo
>>> all_coap4 = UDP6EndpointAddress(socket.getaddrinfo('', 5683, type=socket.SOCK_DGRAM, family=socket.AF_INET6, flags=socket.AI_V4MAPPED)[0][-1])
>>> all_coap4.is_multicast

The authority component of URIs that this endpoint represents


The base URI for this endpoint (typically scheme plus .hostinfo)


True if the remote address is a multicast address, otherwise false.


True if the local address is a multicast address, otherwise false.

class aiocoap.transports.udp6.SockExtendedErr

Bases: aiocoap.transports.udp6._SockExtendedErr

classmethod load(data)
class aiocoap.transports.udp6.MessageInterfaceUDP6(ctx: aiocoap.interfaces.MessageManager, log, loop)

Bases: aiocoap.util.asyncio.RecvmsgDatagramProtocol, aiocoap.interfaces.MessageInterface

ready = None

Future that gets fullfilled by connection_made (ie. don’t send before this is done; handled by create_..._context


Send a given Message object

classmethod create_client_transport_endpoint(ctx: aiocoap.interfaces.MessageManager, log, loop, dump_to)
classmethod create_server_transport_endpoint(ctx: aiocoap.interfaces.MessageManager, log, loop, dump_to, bind)

Return a value suitable for the message’s remote property based on its .opt.uri_host or .unresolved_remote.

May return None, which indicates that the MessageInterface can not transport the message (typically because it is of the wrong scheme).


Deactivate the complete transport, usually irrevertably. When the coroutine returns, the object must have made sure that it can be destructed by means of ref-counting or a garbage collector run.


Implementation of the DatagramProtocol interface, called by the transport.

datagram_msg_received(data, ancdata, flags, address)

Implementation of the RecvmsgDatagramProtocol interface, called by the transport.

datagram_errqueue_received(data, ancdata, flags, address)

Implementation of the DatagramProtocol interface, called by the transport.


Called when the connection is lost or closed.

The argument is an exception object or None (the latter meaning a regular EOF is received or the connection was aborted or closed).