Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
COAP_HANDLER(3)			libcoap	Manual		       COAP_HANDLER(3)

NAME
       coap_handler, coap_register_handler, coap_register_response_handler,
       coap_register_nack_handler, coap_register_ping_handler,
       coap_register_pong_handler, coap_register_event_handler - work with
       CoAP handlers

SYNOPSIS
       #include	<coap2/coap.h>

       void coap_register_handler(coap_resource_t *resource, unsigned char
       method, coap_method_handler_t handler);

       void coap_register_response_handler(coap_context_t *context,
       coap_response_handler_t handler);

       void coap_register_nack_handler(coap_context_t *context,
       coap_nack_handler_t handler);

       void coap_register_ping_handler(coap_context_t *context,
       coap_ping_handler_t handler);

       void coap_register_pong_handler(coap_context_t *context,
       coap_pong_handler_t handler);

       void coap_register_event_handler(coap_context_t *context,
       coap_event_handler_t handler);

       Link with -lcoap-2, -lcoap-2-gnutls, -lcoap-2-openssl or
       -lcoap-2-tinydtls depending on your (D)TLS library type.

DESCRIPTION
       The coap_register_handler() function registers a	callback handler
       handler that is called when there is a URI match	against	the resource
       and there is a method (e.g. PUT,	POST etc.) match. method can be	one of
       the following.

	   COAP_REQUEST_GET
	   COAP_REQUEST_POST
	   COAP_REQUEST_PUT
	   COAP_REQUEST_DELETE
	   COAP_REQUEST_FETCH
	   COAP_REQUEST_PATCH
	   COAP_REQUEST_IPATCH

       The handler function prototype is defined as:

	   typedef void	(*coap_method_handler_t)(coap_context_t	*context,
						 coap_resource_t *resource,
						 coap_session_t	*session,
						 coap_pdu_t *incoming_pdu,
						 coap_string_t *token,
						 coap_string_t *query,
						 coap_pdu_t *response_pdu);

       NOTE: incoming_pdu will be NULL for the GET Handler if this is an
       internally generated Observe Response. coap_find_observer() can be used
       to determine the	subscription information in this case.

       The coap_register_response_handler() function defines a request's
       response	handler	for traffic associated with the	context. The
       application can use this	for handling any response packets, including
       sending a RST packet if this response was unexpected. If	handler	is
       NULL, then the handler is de-registered.

       The handler function prototype is defined as:

	   typedef void	(*coap_response_handler_t)(coap_context_t *context,
						   coap_session_t *session,
						   coap_pdu_t *sent,
						   coap_pdu_t *received,
						   const coap_tid_t id);

       NOTE: sent will only be non NULL	when the request PDU is	Confirmable
       and this	is an ACK or RST response to the request. In general, matching
       of Requests and Responses whould	be done	generating unique Tokens for
       each Request and	then matching up based on the Token in received
       Response.

       The coap_register_nack_handler()	function defines a request's negative
       response	handler	for traffic associated with the	context. If handler is
       NULL, then the handler is de-registered.

       The handler function prototype is defined as:

	   typedef void	(*coap_nack_handler_t)(coap_context_t *context,
					       coap_session_t *session,
					       coap_pdu_t *sent,
					       coap_nack_reason_t reason,
					       const coap_tid_t	id);

       NACKs can be one	of the following

	   COAP_NACK_TOO_MANY_RETRIES
	   COAP_NACK_NOT_DELIVERABLE
	   COAP_NACK_RST
	   COAP_NACK_TLS_FAILED
	   COAP_NACK_ICMP_ISSUE

       The coap_register_ping_handler()	function defines a handler for
       tracking	receipt	of CoAP	ping traffic associated	with the context. If
       handler is NULL,	then the handler is de-registered.

       The handler function prototype is defined as:

	   typedef void	(*coap_ping_handler_t)(coap_context_t *context,
					       coap_session_t *session,
					       coap_pdu_t *received,
					       const coap_tid_t	id);

       The coap_register_pong_handler()	function defines a handler for
       tracking	receipt	of CoAP	ping response traffic associated with the
       context.	If handler is NULL, then the handler is	de-registered.

       The handler function prototype is defined as:

	   typedef void	(*coap_pong_handler_t)(coap_context_t *context,
					       coap_session_t *session,
					       coap_pdu_t *received,
					       const coap_tid_t	id);

       The coap_register_event_handler() function defines a handler for
       tracking	(D)TLS events associated with the context. If handler is NULL,
       then the	handler	is de-registered.

       The handler function prototype is defined as:

	   typedef void	(*coap_event_handler_t)(coap_context_t *context,
						coap_event_t event,
						coap_session_t *session);

       Events can be one of the	following

	   /**
	    * (D)TLS events for	COAP_PROTO_DTLS	and COAP_PROTO_TLS
	    */
	   COAP_EVENT_DTLS_CLOSED	 0x0000
	   COAP_EVENT_DTLS_CONNECTED	 0x01DE
	   COAP_EVENT_DTLS_RENEGOTIATE	 0x01DF
	   COAP_EVENT_DTLS_ERROR	 0x0200
	   /**
	    * TCP events for COAP_PROTO_TCP and	COAP_PROTO_TLS
	    */
	   COAP_EVENT_TCP_CONNECTED	 0x1001
	   COAP_EVENT_TCP_CLOSED	 0x1002
	   COAP_EVENT_TCP_FAILED	 0x1003
	   /**
	    * CSM exchange events for reliable protocols only
	    */
	   COAP_EVENT_SESSION_CONNECTED	 0x2001
	   COAP_EVENT_SESSION_CLOSED	 0x2002
	   COAP_EVENT_SESSION_FAILED	 0x2003

EXAMPLES
       GET Resource Callback Handler

	   #include <coap2/coap.h>

	   void
	   hnd_get_time(coap_context_t *context, coap_resource_t *resource,
	   coap_session_t *session, coap_pdu_t *request, coap_string_t *token,
	   coap_string_t *query, coap_pdu_t *response) {

	     unsigned char buf[40];
	     size_t len;
	     time_t now;

	     /*	... Additional analysis	code for resource, request pdu etc.  ... */

	     /*	After analysis,	generate a suitable response */

	     /*	Note that token, if set, is already in the response pdu	*/

	     now = time(NULL);

	     if	(query != NULL && coap_string_equal(query, coap_make_str_const("secs"))) {
	       /* Output secs since Jan	1 1970 */
	       len = snprintf((char *)buf, sizeof(buf),	"%lu", now);
	     }
	     else {
	       /* Output human-readable	time */
	       struct tm *tmp;
	       tmp = gmtime(&now);
	       if (!tmp) {
		 /* If 'now' is	not valid */
		 response->code	= COAP_RESPONSE_CODE(404);
		 return;
	       }
	       len = strftime((char *)buf, sizeof(buf),	"%b %d %H:%M:%S", tmp);
	     }
	     /*
	      *	Invoke coap_add_data_blocked_response()	to do all the hard work.
	      *
	      *	Define the format - COAP_MEDIATYPE_TEXT_PLAIN -	to add in
	      *	Define how long	this response is valid for (secs) - 1 -	to add in.
	      *
	      *	OBSERVE	Option added internally	if needed within the function
	      *	BLOCK2 Option added internally if output too large
	      *	ETAG Option added internally
	      */
	     coap_add_data_blocked_response(resource, session, request,	response, token,
					    COAP_MEDIATYPE_TEXT_PLAIN, 1,
					    len,
					    buf);

	     /*
	      *	As resource->code has been updated in coap_add_data_blocked_response(),
	      *	the response pdu will be transmitted by	the underlying library.
	      */

	   }

       Packet Response Handler

	   #include <coap2/coap.h>

	   static void
	   response_handler(coap_context_t *ctx, coap_session_t	*session,
	   coap_pdu_t *sent, coap_pdu_t	*received, const coap_tid_t id)	{

	     coap_pdu_t	*pdu = NULL;
	     coap_opt_t	*block_opt;
	     coap_opt_iterator_t opt_iter;
	     unsigned char buf[4];
	     size_t len;
	     unsigned char *databuf;
	     coap_tid_t	tid;

	     /*	check if this is a response to our original request */
	     if	(!check_token(received)) {
	       /* drop if this was just	some message, or send RST in case of notification */
	       if (!sent && (received->type == COAP_MESSAGE_CON	||
			     received->type == COAP_MESSAGE_NON))
		 coap_send_rst(session,	received);
	       return;
	     }

	     if	(received->type	== COAP_MESSAGE_RST) {
	       info("got RST\n");
	       return;
	     }

	     /*	Output the received data, if any */
	     if	(COAP_RESPONSE_CLASS(received->code) ==	2) {
	       /* Additional code to deal with the response */

	     }
	     return;

	   }

SEE ALSO
       coap_observe(3) and coap_resource(3)

FURTHER	INFORMATION
       See "RFC7252: The Constrained Application Protocol (CoAP)" for further
       information.

BUGS
       Please report bugs on the mailing list for libcoap:
       libcoap-developers@lists.sourceforge.net

AUTHORS
       The libcoap project <libcoap-developers@lists.sourceforge.net>

coap_handler 4.2.1		  03/01/2021		       COAP_HANDLER(3)

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | SEE ALSO | FURTHER INFORMATION | BUGS | AUTHORS

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=coap_handler&sektion=3&manpath=FreeBSD+13.0-RELEASE+and+Ports>

home | help