libcoap 4.3.5rc2-develop-4851806


coap_init, coap_startup, coap_cleanup - Work with CoAP initialization


#include <coap3/coap.h>

void coap_startup(void);

void coap_cleanup(void);

For specific (D)TLS library support, link with -lcoap-3-notls, -lcoap-3-gnutls, -lcoap-3-openssl, -lcoap-3-mbedtls, -lcoap-3-wolfssl or -lcoap-3-tinydtls. Otherwise, link with -lcoap-3 to get the default (D)TLS library support.


The CoAP libcoap logic needs to be initialized before there is any use of the libcoap public API. This is done by calling coap_startup().


Function: coap_startup()

The coap_startup() function must be called before any other coap_*() functions are called. It is used to initialize things like mutexes, random number gererators, clocks, TLS libraries etc.

NOTE: This should be called after any other lower layer is initialized. For example, for LwIP, lwip_init() must be called before coap_startup().

NOTE: After the inital call to coap_startup(), subsequent calls are ignored until coap_cleanup() is called.

Function: coap_cleanup()

The coap_cleanup() function is used to cleanup / free any information set up by the coap_startup() function and should be the last coap_*() function called. The only safe function that can be called after coap_cleanup() is coap_startup() to re-initialize the libcoap logic.

NOTE: Calling coap_cleanup() in one thread while continuing to use other coap_*() function calls in a different thread is not supported - even if they are using a different coap_context_t.

NOTE: All other libcoap cleanups should called prior to coap_cleanup(), e.g. coap_free_context(3).



"RFC7252: The Constrained Application Protocol (CoAP)"

for further information.


Please raise an issue on GitHub at to report any bugs.

Please raise a Pull Request at for any fixes.


The libcoap project <>