// -*- mode:doc; -*-
// vim: set syntax=asciidoc tw=0

coap_lwip(3)
============
:doctype: manpage
:man source:   coap_lwip
:man version:  @PACKAGE_VERSION@
:man manual:   libcoap Manual

NAME
----
coap_lwip,
coap_lwip_dump_memory_pools,
coap_lwip_set_input_wait_handler
- Work with CoAP lwip specific API handler

SYNOPSIS
--------
*#include <coap@LIBCOAP_API_VERSION@/coap.h>*

*void coap_lwip_set_input_wait_handler(coap_context_t *_context_,
coap_lwip_input_wait_handler_t _handler_, void *_input_arg_);*

*void coap_lwip_dump_memory_pools(coap_log_t _log_level_);*

DESCRIPTION
-----------
This man page describes the additional libcoap functions that are available
for working with LwIP implementations.

*NOTE:* If the following line is defined in lwipopts.h, then libcoap will
reserve space for one response PDU when allocating coap_pdu_t structures.

[source, c]
----
#define MEMP_STATS 1
----

CALLBACK HANDLER
----------------

*Callback Type: coap_lwip_input_wait_handler_t*

[source, c]
----
/**
 * LwIP callback handler that can be used to wait / timeout for the
 * next input packet.
 *
 * @param arg The argument passed to the coap_lwip_set_input_wait_handler()
 *            function.
 * @param milli_secs Suggested number of milli secs to wait before returning
 *                   if no input.
 *
 * @return @c 1 if packet received, @c 0 for timeout, else @c -1 on error.
 */
typedef int (*coap_lwip_input_wait_handler_t)(void* arg, uint32_t milli_secs);
----

FUNCTIONS
---------

*Function: coap_lwip_set_input_wait_handler()*

The *coap_lwip_set_input_wait_handler*() function is used to define a callback
_handler_ that is invoked by *coap_io_process*(3) which passes in the
_input_arg_ parameter along with a suggested milli-sec wait time parameter
in case there is no input.  This callback _handler_ is used to wait for
(and probably times out) the next input packet.  This allows the application
to define whatever mechanism it wants use for this process.

*Function: coap_lwip_dump_memory_pools()*

The *coap_lwip_dump_memory_pools*() function is used to dump out the current
state of the LwIP memory pools at logging level _log_level_.

This function is always invoked by *coap_free_context*(3) with a _log_level_ of
COAP_LOG_DEBUG.

*NOTE:* For information to be printed out, you need the following two lines in
lwipopts.h

[source, c]
----
#define MEMP_STATS         1
#define LWIP_STATS_DISPLAY 1
----

SEE ALSO
--------
*coap_context*(3) and *coap_io*(3)

FURTHER INFORMATION
-------------------
See

"https://rfc-editor.org/rfc/rfc7252[RFC7252: The Constrained Application Protocol (CoAP)]"

for further information.

BUGS
----
Please report bugs on the mailing list for libcoap:
libcoap-developers@lists.sourceforge.net or raise an issue on GitHub at
https://github.com/obgm/libcoap/issues

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