NAME

       coap_tls_library, coap_dtls_is_supported, coap_tls_is_supported,
       coap_get_tls_library_version, coap_string_tls_version, coap_show_tls_version - Work with
       CoAP contexts

SYNOPSIS

       #include <coap2/coap.h>

       int coap_dtls_is_supported(void);

       int coap_tls_is_supported(void);

       coap_tls_version_t *coap_get_tls_library_version(void);

       *char *coap_string_tls_version(char *buffer, size_t bufsize);

       void coap_show_tls_version(coap_log_t level);

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

DESCRIPTION

       When the libcoap library was built, it will have been compiled using a specific TLS
       implementation type (e.g. OpenSSL, GnuTLS, TinyDTLS or noTLS). When the libcoap library is
       linked into an application, it is possible that the application needs to dynamically
       determine whether DTLS or TLS is supported, what type of TLS implementation libcoap was
       compiled with, as well as detect what is the version of the currently loaded TLS library
       is.

       NOTE: If OpenSSL is being used, then the minimum OpenSSL library version is 1.1.0.

       NOTE: If GnuTLS is being used, then the minimum GnuTLS library version is 3.3.0.

       NOTE: If GnuTLS is going to interoperate with TinyDTLS, then a minimum revision of GnuTLS
       3.5.5 which supports CCM algorithms is required by TinyDTLS as TinyDTLS currently only
       supports CCM.

       Network traffic can be encrypted or un-encrypted with libcoap - how to set this up is
       described in coap_context(3).

       Due to the nature of TLS, there can be Callbacks that are invoked as the TLS session
       negotiates encryption algorithms, encryption keys etc. Where possible, by default, the
       CoAP layer handles all this automatically. However, there is the flexibility of the
       Callbacks for imposing additional security checks etc. when PKI is being used. These
       callbacks need to need to match the TLS implementation type.

       The coap_dtls_is_supported() function returns 1 if support for DTLS is enabled, otherwise
       0;

       The coap_tls_is_supported() function returns 1 if support for TLS is enabled, otherwise 0;

       The coap_get_tls_library_version() function returns the TLS implementation type and
       library version in a coap_tls_version_t* structure.

       The coap_string_tls_version() function is used to update the provided buffer with
       information about the current (D)TLS library that libcoap was built against, as well as
       the current linked version of the (D)TLS library. buffer defines the buffer to provide the
       information and bufsize is the size of buffer.

       The coap_show_tls_version() function is used log information about the current (D)TLS
       library that libcoap was built against, as well as the current linked version of the
       (D)TLS library. level defines the minimum logging level for this information to be output
       using coap_log().

           typedef enum coap_tls_library_t {
             COAP_TLS_LIBRARY_NOTLS = 0, /**< No DTLS library */
             COAP_TLS_LIBRARY_TINYDTLS,  /**< Using TinyDTLS library */
             COAP_TLS_LIBRARY_OPENSSL,   /**< Using OpenSSL library */
             COAP_TLS_LIBRARY_GNUTLS,    /**< Using GnuTLS library */
           } coap_tls_library_t;

           typedef struct coap_tls_version_t {
             uint64_t version; /* (D)TLS runtime Library Version */
             coap_tls_library_t type; /**< Library type. One of COAP_TLS_LIBRARY_* */
             uint64_t built_version; /* (D)TLS Built against Library Version */
           }

RETURN VALUES

       coap_dtls_is_supported() and coap_tls_is_supported() functions return 0 if there is no
       support, 1 if support is available.

       coap_get_tls_library_version() function returns the TLS implementation type and library
       version in a coap_tls_version_t* structure.

       coap_string_tls_version() function returns a pointer to the provided buffer.

SEE ALSO

       coap_context(3) and coap_logging(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>