NAME

       coap_logging, coap_log, coap_log_emerg, coap_log_alert, coap_log_crit, coap_log_err,
       coap_log_warn, coap_log_info, coap_log_notice, coap_log_debug, coap_log_oscore,
       coap_get_log_level, coap_set_log_level, coap_dtls_log, coap_dtls_get_log_level,
       coap_dtls_set_log_level, coap_set_log_handler, coap_package_name, coap_package_version,
       coap_package_build, coap_set_show_pdu_output, coap_show_pdu, coap_endpoint_str,
       coap_session_str, coap_print_addr, coap_print_ip_addr - Work with CoAP logging

SYNOPSIS

       #include <coap3/coap.h>

       void coap_log(coap_log_t level, const char *format, ...);

       void coap_log_emerg(const char *format, ...);

       void coap_log_alert(const char *format, ...);

       void coap_log_crit(const char *format, ...);

       void coap_log_err(const char *format, ...);

       void coap_log_warn(const char *format, ...);

       void coap_log_info(const char *format, ...);

       void coap_log_notice(const char *format, ...);

       void coap_log_debug(const char *format, ...);

       void coap_log_oscore(const char *format, ...);

       void coap_set_log_level(coap_log_t level);

       coap_log_t coap_get_log_level(void);

       void coap_dtls_log(coap_log_t level, const char *format, ...);

       void coap_dtls_set_log_level(coap_log_t level);

       coap_log_t coap_dtls_get_log_level(void);

       void coap_set_log_handler(coap_log_handler_t handler);

       const char *coap_package_name(void);

       const char *coap_package_version(void);

       const char *coap_package_build(void);

       void coap_set_show_pdu_output(int use_fprintf);

       void coap_show_pdu(coap_log_t level, const coap_pdu_t *pdu);

       const char *coap_endpoint_str(const coap_endpoint_t *endpoint);

       const char *coap_session_str(const coap_session_t *session);

       size_t coap_print_addr(const coap_address_t *address, unsigned char *buffer, size_t
       length);

       const char *coap_print_ip_addr(const coap_address_t *address, char *buffer, size_t
       length);

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

DESCRIPTION

       The logging sub-system supports logging at different levels, and depending on the selected
       logging level, outputs the appropriate information.

       Logging by default is to stderr or stdout depending on the logging level of the log entry.
       It ia possible to send the logging information to an application logging callback handler
       for processing by the application.

       Logging levels (coap_log_t) are defined as follows (based on the syslog() names and
       values):

       COAP_LOG_EMERG
           Emergency level (0).

       COAP_LOG_ALERT
           Alert level (1).

       COAP_LOG_CRIT
           Critical level (2).

       COAP_LOG_ERR
           Error level (3).

       COAP_LOG_WARN
           Warning level (the default) (4).

       COAP_LOG_NOTICE
           Notice level (5).

       COAP_LOG_INFO
           Information level (6).

       COAP_LOG_DEBUG
           Debug level (7).

       With additional level:

       COAP_LOG_OSCORE
           Debug OSCORE information (8).

       NOTE: The maximum logging level in the libcoap library may have been updated by the use of
       ./configure --enable-max-logging-level=X (where X is 0 to 8 inclusive) which may disable
       some of the higher logging levels to save code space.

FUNCTIONS

       Function: coap_log()

       The coap_log() function is used to log information at the appropriate level. The rest of
       the parameters follow the standard printf() function format. Where possible, the
       coap_log_*() functions should be used instead.

       Function: coap_log_emerg()

       The coap_log_emerg() function provides a wrapper to the coap_log() function with level set
       to COAP_LOG_EMERG. The parameters follow the standard printf() function format.

       Function: coap_log_alert()

       The coap_log_alert() function provides a wrapper to the coap_log() function with level set
       to COAP_LOG_ALERT. The parameters follow the standard printf() function format.

       Function: coap_log_crit()

       The coap_log_crit() function provides a wrapper to the coap_log() function with level set
       to COAP_LOG_CRIT. The parameters follow the standard printf() function format.

       Function: coap_log_err()

       The coap_log_err() function provides a wrapper to the coap_log() function with level set
       to COAP_LOG_ERR. The parameters follow the standard printf() function format.

       Function: coap_log_warn()

       The coap_log_warn() function provides a wrapper to the coap_log() function with level set
       to COAP_LOG_WARN. The parameters follow the standard printf() function format.

       Function: coap_log_notice()

       The coap_log_notice() function provides a wrapper to the coap_log() function with level
       set to COAP_LOG_NOTICE. The parameters follow the standard printf() function format.

       Function: coap_log_info()

       The coap_log_info() function provides a wrapper to the coap_log() function with level set
       to COAP_LOG_INFO. The parameters follow the standard printf() function format.

       Function: coap_log_debug()

       The coap_log_debug() function provides a wrapper to the coap_log() function with level set
       to COAP_LOG_DEBUG. The parameters follow the standard printf() function format.

       Function: coap_log_oscore()

       The coap_log_oscore() function provides a wrapper to the coap_log() function with level
       set to COAP_LOG_OSCORE. The parameters follow the standard printf() function format.

       Function: coap_set_log_level()

       The coap_set_log_level() function is used to set the current logging level for output by
       any subsequent coap_log() calls. Output is only logged if the coap_log() level definition
       is smaller than or equal to the current logging level.

       Function: coap_get_log_level()

       The coap_get_log_level() function is used to get the current logging level.

       Function: coap_dtls_log()

       The coap_dtls_log() function is used to log (D)TLS library information at the appropriate
       level. The rest of the parameters follow the standard printf() function format.

       Function: coap_dtls_set_log_level()

       The coap_dtls_set_log_level() function is used to set the current logging level for output
       by any subsequent coap_dtls_log() calls. Output is only logged if the coap_dtls_log()
       level definition is smaller than or equal to the current DTLS logging level.

       Function: coap_dtls_get_log_level()

       The coap_dtls_get_log_level() function is used to get the current logging level for the
       DTLS library.

       Function: coap_set_log_handler()

       The coap_set_log_handler()* function can be used to define an alternative logging handler
       for processing any logging messages. The logging handler prototype is defined as:

           typedef void (*coap_log_handler_t) (coap_log_t level, const char *message);

       Function: coap_package_name()

       The coap_package_name() function returns the name of this library.

       Function: coap_package_version()

       The coap_package_version() function returns the version of this library.

       Function: coap_package_build()

       The coap_package_build() function returns the git information (as in "git describe
       --tags") for the build of this library or version of this library if git is not used.

       Function: coap_set_show_pdu_output()

       The coap_set_show_pdu_output() function defines whether the output from coap_show_pdu() is
       to be either sent to stdout/stderr, or output using coap_log(). use_fprintf is set to 1
       for stdout/stderr (the default), and use_fprintf is set to 0 for coap_log().

       Function: coap_show_pdu()

       The coap_show_pdu() function is used to decode the pdu, outputting as appropriate for
       logging level. Where the output goes is dependent on coap_set_show_pdu_output().

       NOTE: If pdu has not been associated with a CoAP session (i.e. not a received PDU or
       coap_send() not yet called), then the output assumes that this pdu is of type unreliable.

       Function: coap_endpoint_str()

       The coap_endpoint_str() function returns a description string of the endpoint.

       Function: coap_session_str()

       The coap_session_str() function is used to get a string containing the information about
       the session.

       Function: coap_print_addr()

       The coap_print_addr() function returns the length of the description string containing the
       IP address and port from address, updating buffer which has a maximum length length.

       Function: coap_print_ip_addr()

       The coap_print_ip_addr() function returns a description string of the IP address only for
       address. buffer is updated, which has a maximum length of length.

RETURN VALUES

       coap_package_name(), coap_package_version() and coap_package_build() return the
       appropriate zero-terminated character string.

       coap_get_log_level() returns the current logging level.

       coap_dtls_get_log_level() returns the current logging level for the DTLS library
       specifics.

       coap_endpoint_str() returns a description string of the endpoint.

       coap_session_str() returns a description string of the session.

       coap_print_addr() returns the length of buffer that has been updated with an ascii
       readable IP address and port for address.

       coap_print_ip_addr() returns a pointer to the ascii readable IP address only for address.

SEE ALSO

       coap_context(3) and coap_session(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 or raise an issue on GitHub at
       https://github.com/obgm/libcoap/issues

AUTHORS

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