Jon Shallow
132c726190
Sending off multiple CON requests with the same token without waiting for any responses, causes the first one to be sent with the remainder ending up in the delayqueue. On receipt of ACK, coap_remove_from_queue() called in coap_dispatch(), which returns the MID matching entry that was in the send queue, and then the next entry on the delayqueue is removed from delayqueue and then sent which puts the request on the sendqueue for any required re-transmissions. coap_cancel_all_messages() should not be called in handle_response() following the logic above if response is type ACK. If coap_cancel_all_messages() is subsequently called with the same (possibly empty) token as the next request that is being sent, then the next sendqueue entry is inadvertantly deleted. As there is now no sendqueue entry on receipt of the next ACK, the next delayqueue entry is not sent off. Only call coap_cancel_all_messages() if response is not of type ACK (i.e. a separate response). Report on tokens being the same as the previous one to encourage application coders to use different tokens.
libcoap: A C implementation of the Constrained Application Protocol (RFC 7252)
Copyright (C) 2010—2022 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 http://coap.technology.
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, LwIP and Espressif/ESP-IDF hosted environments.
The following RFCs are supported
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RFC7252: The Constrained Application Protocol (CoAP)
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RFC7390: Group Communication for the Constrained Application Protocol (CoAP)
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RFC7641: Observing Resources in the Constrained Application Protocol (CoAP)
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RFC7959: Block-Wise Transfers in the Constrained Application Protocol (CoAP)
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RFC7967: Constrained Application Protocol (CoAP) Option for No Server Response
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RFC8132: PATCH and FETCH Methods for the Constrained Application Protocol (CoAP)
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RFC8323: CoAP (Constrained Application Protocol) over TCP, TLS, and WebSockets [No WebSockets support]
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RFC8768: Constrained Application Protocol (CoAP) Hop-Limit Option
There is (D)TLS support for the following libraries
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OpenSSL (Minimum version 1.1.0) [PKI, PSK and PKCS11]
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GnuTLS (Minimum version 3.3.0) [PKI, PSK, RPK(3.6.6+) and PKCS11]
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Mbed TLS (Minimum version 2.7.10) [PKI and PSK]
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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.