daa4e05e18
Add in limited caching for multiple clients requesting an Observe subscription for the same upstream session resource so that only a single observation request is sent upstream and any unsolicited response is sent back to all the requesting clients. This requires a change in the recently added handler registered to coap_register_proxy_response_handler(), which no longer should no longer call coap_proxy_forward_response(), but just return a PDU for forwarding on.
libcoap: A C implementation of the Constrained Application Protocol (RFC 7252)
Copyright (C) 2010—2025 by Olaf Bergmann bergmann@tzi.org and others
ABOUT LIBCOAP
libcoap is a C implementation of a lightweight application-protocol for devices that are constrained their resources such as computing power, RF range, memory, bandwidth, or network packet sizes. This protocol, CoAP, is standardized by the IETF as RFC 7252. For further information related to CoAP, see https://coap.space or CoAP Wiki.
You might want to check out libcoap-minimal for usage examples.
DOCUMENTATION
Documentation and further information can be found at https://libcoap.net.
PACKAGE CONTENTS
This package contains a protocol parser and basic networking functions for platforms with support for malloc() and BSD-style sockets. In addition, there is support for Contiki-NG, Espressif/ESP-IDF, LwIP and RIOT-OS hosted environments.
The following RFCs are supported
-
RFC7390: Group Communication for the Constrained Application Protocol (CoAP)
-
RFC7641: Observing Resources in the Constrained Application Protocol (CoAP)
-
RFC7959: Block-Wise Transfers in the Constrained Application Protocol (CoAP)
-
RFC7967: Constrained Application Protocol (CoAP) Option for No Server Response
-
RFC8132: PATCH and FETCH Methods for the Constrained Application Protocol (CoAP)
-
RFC8323: CoAP (Constrained Application Protocol) over TCP, TLS, and WebSockets
-
RFC8516: "Too Many Requests" Response Code for the Constrained Application Protocol
-
RFC8613: Object Security for Constrained RESTful Environments (OSCORE)
-
RFC8768: Constrained Application Protocol (CoAP) Hop-Limit Option
-
RFC8974: Extended Tokens and Stateless Clients in the Constrained Application Protocol (CoAP)
There is (D)TLS support for the following libraries
-
OpenSSL (Minimum version 1.1.0) [PKI, PSK and PKCS11]
-
GnuTLS (Minimum version 3.3.0) [PKI, PSK, RPK(3.6.6+) and PKCS11]
-
Mbed TLS (Minimum version 2.7.10) [PKI and PSK]
-
wolfSSL (Minimum version 5.2.0) [PKI, PSK, RPK(5.6.4+) and DTLS1.3(5.4.0+)]
-
TinyDTLS [PSK and RPK] [DTLS Only]
The examples directory contain a CoAP client, CoAP Resource Directory server and a CoAP server to demonstrate the use of this library.
BUILDING
Further information can be found at https://libcoap.net/install.html and BUILDING.
LICENSE INFORMATION
This library is published as open-source software without any warranty of any kind. Use is permitted under the terms of the simplified BSD license. It includes public domain software. libcoap binaries may also include open-source software with their respective licensing terms. Please refer to LICENSE for further details.