'\" t
.\" Title: coap_handler
.\" Author: [see the "AUTHORS" section]
.\" Generator: DocBook XSL Stylesheets v1.79.1
.\" Date: 04/13/2019
.\" Manual: libcoap Manual
.\" Source: coap_handler 4.2.0
.\" Language: English
.\"
.TH "COAP_HANDLER" "3" "04/13/2019" "coap_handler 4\&.2\&.0" "libcoap Manual"
.\" -----------------------------------------------------------------
.\" * Define some portability stuff
.\" -----------------------------------------------------------------
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.\" http://bugs.debian.org/507673
.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.ie \n(.g .ds Aq \(aq
.el .ds Aq '
.\" -----------------------------------------------------------------
.\" * set default formatting
.\" -----------------------------------------------------------------
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.\" -----------------------------------------------------------------
.\" * MAIN CONTENT STARTS HERE *
.\" -----------------------------------------------------------------
.SH "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
.SH "SYNOPSIS"
.sp
\fB#include \fR
.sp
\fBvoid coap_register_handler(coap_resource_t *\fR\fB\fIresource\fR\fR\fB, unsigned char \fR\fB\fImethod\fR\fR\fB, coap_method_handler_t \fR\fB\fIhandler\fR\fR\fB);\fR
.sp
\fBvoid coap_register_response_handler(coap_context_t *\fR\fB\fIcontext\fR\fR\fB, coap_response_handler_t \fR\fB\fIhandler\fR\fR\fB)\fR;
.sp
\fBvoid coap_register_nack_handler(coap_context_t *\fR\fB\fIcontext\fR\fR\fB, coap_nack_handler_t \fR\fB\fIhandler\fR\fR\fB)\fR;
.sp
\fBvoid coap_register_ping_handler(coap_context_t *\fR\fB\fIcontext\fR\fR\fB, coap_ping_handler_t \fR\fB\fIhandler\fR\fR\fB)\fR;
.sp
\fBvoid coap_register_pong_handler(coap_context_t *\fR\fB\fIcontext\fR\fR\fB, coap_pong_handler_t \fR\fB\fIhandler\fR\fR\fB)\fR;
.sp
\fBvoid coap_register_event_handler(coap_context_t *\fR\fB\fIcontext\fR\fR\fB, coap_event_handler_t \fR\fB\fIhandler\fR\fR\fB)\fR;
.sp
Link with \fB\-lcoap\-2\fR, \fB\-lcoap\-2\-gnutls\fR, \fB\-lcoap\-2\-openssl\fR or \fB\-lcoap\-2\-tinydtls\fR depending on your (D)TLS library type\&.
.SH "DESCRIPTION"
.sp
The \fBcoap_register_handler\fR() function registers a callback handler \fIhandler\fR that is called when there is a URI match against the \fIresource\fR and there is a \fImethod\fR (e\&.g\&. PUT, POST etc\&.) match\&. \fImethod\fR can be one of the following\&.
.sp
.if n \{\
.RS 4
.\}
.nf
COAP_REQUEST_GET
COAP_REQUEST_POST
COAP_REQUEST_PUT
COAP_REQUEST_DELETE
COAP_REQUEST_FETCH
COAP_REQUEST_PATCH
COAP_REQUEST_IPATCH
.fi
.if n \{\
.RE
.\}
.sp
The handler function prototype is defined as:
.sp
.if n \{\
.RS 4
.\}
.nf
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);
.fi
.if n \{\
.RE
.\}
.sp
The \fBcoap_register_response_handler\fR() function defines a request\(cqs response \fIhandler\fR for traffic associated with the \fIcontext\fR\&. The application can use this for handling any response packets, including sending a RST packet if this response was unexpected\&. If \fIhandler\fR is NULL, then the handler is de\-registered\&.
.sp
The handler function prototype is defined as:
.sp
.if n \{\
.RS 4
.\}
.nf
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);
.fi
.if n \{\
.RE
.\}
.sp
The \fBcoap_register_nack_handler\fR() function defines a request\(cqs negative response \fIhandler\fR for traffic associated with the \fIcontext\fR\&. If \fIhandler\fR is NULL, then the handler is de\-registered\&.
.sp
The handler function prototype is defined as:
.sp
.if n \{\
.RS 4
.\}
.nf
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);
.fi
.if n \{\
.RE
.\}
.sp
The \fBcoap_register_ping_handler\fR() function defines a \fIhandler\fR for tracking CoAP ping traffic associated with the \fIcontext\fR\&. If \fIhandler\fR is NULL, then the handler is de\-registered\&.
.sp
The handler function prototype is defined as:
.sp
.if n \{\
.RS 4
.\}
.nf
typedef void (*coap_ping_handler_t)(coap_context_t *context,
coap_session_t *session,
coap_pdu_t *received,
const coap_tid_t id);
.fi
.if n \{\
.RE
.\}
.sp
The \fBcoap_register_pong_handler\fR() function defines a \fIhandler\fR for tracking CoAP TCP ping response traffic associated with the \fIcontext\fR\&. If \fIhandler\fR is NULL, then the handler is de\-registered\&.
.sp
The handler function prototype is defined as:
.sp
.if n \{\
.RS 4
.\}
.nf
typedef void (*coap_pong_handler_t)(coap_context_t *context,
coap_session_t *session,
coap_pdu_t *received,
const coap_tid_t id);
.fi
.if n \{\
.RE
.\}
.sp
The \fBcoap_register_event_handler\fR() function defines a \fIhandler\fR for tracking (D)TLS events associated with the \fIcontext\fR\&. If \fIhandler\fR is NULL, then the handler is de\-registered\&.
.sp
The handler function prototype is defined as:
.sp
.if n \{\
.RS 4
.\}
.nf
typedef void (*coap_event_handler_t)(coap_context_t *context,
coap_event_t event,
coap_session_t *session);
.fi
.if n \{\
.RE
.\}
.sp
Events can be one of the following
.sp
.if n \{\
.RS 4
.\}
.nf
/**
* (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
.fi
.if n \{\
.RE
.\}
.SH "EXAMPLES"
.sp
\fBGET Resource Callback Handler\fR
.sp
.if n \{\
.RS 4
.\}
.nf
#include
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 \*(Aqnow\*(Aq 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\&.
*/
}
.fi
.if n \{\
.RE
.\}
.sp
\fBPacket Response Handler\fR
.sp
.if n \{\
.RS 4
.\}
.nf
#include
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\en");
return;
}
/* Output the received data, if any */
if (COAP_RESPONSE_CLASS(received\->code) == 2) {
/* Additional code to deal with the response */
}
return;
}
.fi
.if n \{\
.RE
.\}
.SH "SEE ALSO"
.sp
\fBcoap_resource\fR(3)
.SH "FURTHER INFORMATION"
.sp
See "RFC7252: The Constrained Application Protocol (CoAP)" for further information\&.
.SH "BUGS"
.sp
Please report bugs on the mailing list for libcoap: libcoap\-developers@lists\&.sourceforge\&.net
.SH "AUTHORS"
.sp
The libcoap project