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libcoap/man/coap_handler.txt.in
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// -*- mode:doc; -*-
// vim: set syntax=asciidoc,tw=0:
coap_handler(3)
=================
:doctype: manpage
:man source: coap_handler
:man version: @PACKAGE_VERSION@
:man manual: libcoap Manual
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 <coap@LIBCOAP_API_VERSION@/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-@LIBCOAP_API_VERSION@*, *-lcoap-@LIBCOAP_API_VERSION@-gnutls*,
*-lcoap-@LIBCOAP_API_VERSION@-openssl* or
*-lcoap-@LIBCOAP_API_VERSION@-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:
[source, c]
----
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);
----
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:
[source, c]
----
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);
----
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:
[source, c]
----
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);
----
The *coap_register_ping_handler*() function defines a _handler_ for tracking
CoAP ping traffic associated with the _context_. If _handler_ is NULL, then
the handler is de-registered.
The handler function prototype is defined as:
[source, c]
----
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
CoAP TCP ping response traffic associated with the _context_.
If _handler_ is NULL, then the handler is de-registered.
The handler function prototype is defined as:
[source, c]
----
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:
[source, c]
----
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*
[source, c]
--
#include <coap@LIBCOAP_API_VERSION@/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*
[source, c]
--
#include <coap@LIBCOAP_API_VERSION@/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_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>