// -*- mode:doc; -*- // vim: set syntax=asciidoc,tw=0: coap_resource(3) ================= :doctype: manpage :man source: coap_resource :man version: @PACKAGE_VERSION@ :man manual: libcoap Manual NAME ---- coap_resource, coap_resource_init, coap_resource_unknown_init, coap_resource_proxy_uri_init, coap_add_resource, coap_delete_resource, coap_resource_set_mode, coap_resource_set_userdata, coap_resource_get_userdata, coap_resource_release_userdata_handler, coap_resource_get_uri_path - Work with CoAP resources SYNOPSIS -------- *#include * *coap_resource_t *coap_resource_init(coap_str_const_t *_uri_path_, int _flags_);* *coap_resource_t *coap_resource_unknown_init(coap_method_handler_t _put_handler_);* *coap_resource_t *coap_resource_proxy_uri_init(coap_method_handler_t _proxy_handler_, size_t _host_name_count_, const char *_host_name_list_[]);* *void coap_add_resource(coap_context_t *_context_, coap_resource_t *_resource_);* *int coap_delete_resource(coap_context_t *_context_, coap_resource_t *_resource_);* *void coap_resource_set_mode(coap_resource_t *_resource_, int _mode_);* *void coap_resource_set_userdata(coap_resource_t *_resource_, void *_data_);* *void *coap_resource_get_userdata(coap_resource_t *_resource_);* *void coap_resource_release_userdata_handler(coap_context_t *_context_, coap_resource_release_userdata_handler_t _callback_);* *coap_str_const_t *coap_resource_get_uri_path(coap_resource_t *_resource_);* For specific (D)TLS library support, link with *-lcoap-@LIBCOAP_API_VERSION@-notls*, *-lcoap-@LIBCOAP_API_VERSION@-gnutls*, *-lcoap-@LIBCOAP_API_VERSION@-openssl*, *-lcoap-@LIBCOAP_API_VERSION@-mbedtls* or *-lcoap-@LIBCOAP_API_VERSION@-tinydtls*. Otherwise, link with *-lcoap-@LIBCOAP_API_VERSION@* to get the default (D)TLS library support. DESCRIPTION ----------- CoAP Resources on a CoAP Server need to be created and updated etc. The URI in the request packet defines the resource to work with, with possibly the Query referring to a sub-resource. When resources are configured on the CoAP server, the URI to match against in the request packet is specified. Callback Handlers are then added to the resource to handle the different request methods. Adding Attributes allows textual information to be added to the resource which can then be reported back to any client doing a "GET .well-known/core" request. If an incoming packet request matches a resource's URI and Method, then the appropriate callback resource handler is invoked to process the packet which then should update a suitable response packet for sending back to the requester. There is support for handling incoming packets where the URI is unknown. This could, for example, happen when a PUT request is trying to create a new resource. It is the responsibility of the unknown resource callback handler to either create a new resource for the URI or just manage things separately. CoAP Observe (RFC 7641) is not supported for unknown resources, so a new resource with GET handler must be created by the unknown resource callback handle matching the URI which then can be Observable. The *coap_resource_init*() function returns a newly created _resource_ of type _coap_resource_t_ * . _uri_path_ specifies the uri string path to match against. _flags_ is used to define whether the _resource_ is of type Confirmable Message or Non-Confirmable Message for any "observe" responses. See *coap_observe*(3). _flags_ can be one of the following definitions or'ed together. [horizontal] *COAP_RESOURCE_FLAGS_NOTIFY_NON*:: Set the notification message type to non-confirmable for any trigggered "observe" responses with type set to confirmable every 5 packets as required by RFC7641 section-4.5. *COAP_RESOURCE_FLAGS_NOTIFY_NON_ALWAYS*:: Set the notification message type to always non-confirmable for any trigggered "observe" responses. This should only be used if a upper layer protocol requires it. *COAP_RESOURCE_FLAGS_NOTIFY_CON*:: Set the notification message type to confirmable for any trigggered "observe" responses. *COAP_RESOURCE_FLAGS_RELEASE_URI*:: Free off the coap_str_const_t for _uri_path_ when the _resource_ is deleted. *NOTE:* _uri_path_, if not 7 bit readable ASCII, binary bytes must be hex encoded according to the rules defined in RFC3968 Section 2.1. The *coap_resource_unknown_init*() function returns a newly created _resource_ of type _coap_resource_t_ *. _put_handler_ is automatically added to the _resource_ to handle PUT requests to resources that are unknown. Additional handlers can be added to this resource if required. The *coap_resource_proxy_uri_init*() function returns a newly created _resource_ of type _coap_resource_t_ *. _proxy_handler_ is automatically added to the _resource_ to handle PUT/POST/GET etc. requests that use the Proxy-Uri: option. There is no need to add explicit request type handlers. One or more names by which the proxy is known by (IP address, DNS name etc.) must be supplied in the array defined by _host_name_list_[] which has a count of _host_name_count_. This is used to check whether the current endpoint is the proxy target address. The *coap_add_resource*() function registers the given _resource_ with the _context_. The _resource_ must have been created by *coap_resource_init*(), *coap_resource_unknown_init*() or *coap_resource_proxy_uri_init*(). The storage allocated for the _resource_ will be released by *coap_delete_resource*(). As the _uri_path_ of the resource has to be unique across all of the resources associated with a _context_, *coap_add_resource*() (or *coap_add_resource_release*()) will delete any previous _resource_ with the same _uri_path_ before adding in the new _resource_. The *coap_delete_resource*() function deletes a _resource_ identified by _resource_ from _context_. The storage allocated for that _resource_ is freed, along with any attrigutes associated with the _resource_. The *coap_resource_set_mode*() changes the notification message type of _resource_ to the given _mode_ which must be one of COAP_RESOURCE_FLAGS_NOTIFY_NON, COAP_RESOURCE_FLAGS_NOTIFY_NON_ALWAYS or COAP_RESOURCE_FLAGS_NOTIFY_CON. The *coap_resource_set_userdata*() function allows a pointer to user _data_ to be associated with a _resource_ that can accessed in any callback that includes _resource_ as a parameter. *NOTE:* _data_ must point to a static, or allocated, block of memory. The *coap_resource_get_userdata*() function obtains the user data pointer from the _resource_ that had previously been set up by *coap_resource_set_userdata*(). The *coap_resource_release_userdata_handler*() function defines the _context_ wide _callback_ handler to call to release the allocated user data that has been added to the resource using *coap_resource_set_userdata*() when the resource is deleted. _callback_ can be NULL (which is the default) if nothing needs to be freed off. The *coap_resource_get_uri_path*() function is used to obtain the UriPath of the _resource_ definion. RETURN VALUES ------------- The *coap_resource_init*(), *coap_resource_unknown_init*() and *coap_resource_proxy_uri_init*() functions return a newly created resource or NULL if there is a malloc failure. The *coap_delete_resource*() function return 0 on failure (_resource_ not found), 1 on success. The *coap_resource_get_userdata*() function returns the value previously set by the *coap_resource_set_userdata*() function or NULL. The *coap_resource_get_uri_path*() function returns the uri_path or NULL if there was a failure. EXAMPLES -------- *Fixed Resources Set Up* [source, c] ---- #include #define INDEX "This is an example server using libcoap\n" static void hnd_get_index(coap_resource_t *resource, coap_session_t *session, const coap_pdu_t *request, const coap_string_t *query, coap_pdu_t *response) { unsigned char buf[3]; /* Remove (void) definition if variable is used */ (void)resource; (void)session; (void)request; (void)query; coap_pdu_set_code(response, COAP_RESPONSE_CODE_CONTENT); coap_add_option(response, COAP_OPTION_CONTENT_TYPE, coap_encode_var_safe(buf, sizeof(buf), COAP_MEDIATYPE_TEXT_PLAIN), buf); coap_add_option(response, COAP_OPTION_MAXAGE, coap_encode_var_safe(buf, sizeof(buf), 0x2ffff), buf); coap_add_data(response, strlen(INDEX), (const uint8_t *)INDEX); coap_pdu_set_code(response, COAP_RESPONSE_CODE_CONTENT); } static void hnd_delete_time(coap_resource_t *resource, coap_session_t *session, const coap_pdu_t *request, const coap_string_t *query, coap_pdu_t *response) { /* Remove (void) definition if variable is used */ (void)resource; (void)session; (void)request; (void)query; /* .. code .. */ coap_pdu_set_code(response, COAP_RESPONSE_CODE_DELETED); } static void hnd_get_time(coap_resource_t *resource, coap_session_t *session, const coap_pdu_t *request, const coap_string_t *query, coap_pdu_t *response) { /* Remove (void) definition if variable is used */ (void)resource; (void)session; (void)request; (void)query; (void)response; /* .. code .. */ coap_pdu_set_code(response, COAP_RESPONSE_CODE_CONTENT); } static void hnd_put_time(coap_resource_t *resource, coap_session_t *session, const coap_pdu_t *request, const coap_string_t *query, coap_pdu_t *response) { /* Remove (void) definition if variable is used */ (void)resource; (void)session; (void)request; (void)query; (void)response; /* .. code .. */ coap_pdu_set_code(response, COAP_RESPONSE_CODE_CHANGED); } static void init_resources(coap_context_t *ctx) { coap_resource_t *r; /* Create a resource to return general information */ r = coap_resource_init(NULL, 0); coap_register_handler(r, COAP_REQUEST_GET, hnd_get_index); /* Document resource for '.well-known/core' request */ coap_add_attr(r, coap_make_str_const("ct"), coap_make_str_const("0"), 0); coap_add_attr(r, coap_make_str_const("title"), coap_make_str_const("\"General Info\""), 0); coap_add_resource(ctx, r); /* Create a resource to return return or update time */ r = coap_resource_init(coap_make_str_const("time"), COAP_RESOURCE_FLAGS_NOTIFY_CON); coap_resource_set_get_observable(r, 1); coap_register_handler(r, COAP_REQUEST_GET, hnd_get_time); coap_register_handler(r, COAP_REQUEST_PUT, hnd_put_time); coap_register_handler(r, COAP_REQUEST_DELETE, hnd_delete_time); /* Document resource for 'time' request */ coap_add_attr(r, coap_make_str_const("ct"), coap_make_str_const("0"), 0); coap_add_attr(r, coap_make_str_const("title"), coap_make_str_const("\"Internal Clock\""), 0); coap_add_attr(r, coap_make_str_const("rt"), coap_make_str_const("\"secs\""), 0); coap_add_attr(r, coap_make_str_const("if"), coap_make_str_const("\"clock\""), 0); coap_add_resource(ctx, r); } ---- *Dynamic Resources Set Up* [source, c] ---- #include /* Regular DELETE handler - used by resources created by the * Unknown Resource PUT handler */ static void hnd_delete(coap_resource_t *resource, coap_session_t *session, const coap_pdu_t *request, const coap_string_t *query, coap_pdu_t *response) { /* Remove (void) definition if variable is used */ (void)session; (void)request; (void)query; (void)response; /* .. code .. */ /* Dynamic resource no longer required - delete it */ coap_delete_resource(coap_session_get_context(session), resource); coap_pdu_set_code(response, COAP_RESPONSE_CODE_DELETED); } /* Regular GET handler - used by resources created by the * Unknown Resource PUT handler */ static void hnd_get(coap_resource_t *resource, coap_session_t *session, const coap_pdu_t *request, const coap_string_t *query, coap_pdu_t *response) { coap_str_const_t *get_uri_path; /* Remove (void) definition if variable is used */ (void)resource; (void)session; (void)request; (void)query; (void)response; /* * request will be NULL if an Observe triggered request, so the uri_path, * if needed, must be abstracted from the resource. * The uri_path string is a const pointer */ get_uri_path = coap_resource_get_uri_path(resource); /* .. code .. */ coap_pdu_set_code(response, COAP_RESPONSE_CODE_CONTENT); } /* Regular PUT handler - used by resources created by the * Unknown Resource PUT handler */ static void hnd_put(coap_resource_t *resource, coap_session_t *session, const coap_pdu_t *request, const coap_string_t *query, coap_pdu_t *response) { /* Remove (void) definition if variable is used */ (void)resource; (void)session; (void)query; coap_string_t *put_uri_path; size_t length; const uint8_t *data; size_t offset; size_t total; int new_resource = 0; /* get the uri_path */ put_uri_path = coap_get_uri_path(request); if (!put_uri_path) { coap_pdu_set_code(response, COAP_RESPONSE_CODE_NOT_FOUND); return; } coap_get_data_large(request, &length, &data, &offset, &total); /* .. code .. */ /* Need to do this as coap_get_uri_path() created it */ coap_delete_string(put_uri_path); if (length + offset < total) coap_pdu_set_code(response, COAP_RESPONSE_CODE_CONTINUE); else if (new_resource) coap_pdu_set_code(response, COAP_RESPONSE_CODE_CREATED); else coap_pdu_set_code(response, COAP_RESPONSE_CODE_CHANGED); } static int check_url_fn(coap_string_t *uri_path, uint8_t code) { /* Remove (void) definition if variable is used */ (void)uri_path; (void)code; /* Code to determine whether the uri is valid or not */ return 1; } /* Unknown Resource PUT handler */ static void hnd_unknown_put(coap_resource_t *resource, coap_session_t *session, const coap_pdu_t *request, const coap_string_t *query, coap_pdu_t *response) { /* Remove (void) definition if variable is used */ (void)resource; coap_pdu_code_t req_code = coap_pdu_get_code(request); coap_resource_t *r; coap_string_t *uri_path; /* get the uri_path - which will get used by coap_resource_init() */ uri_path = coap_get_uri_path(request); if (!uri_path) { coap_pdu_set_code(response, COAP_RESPONSE_CODE_NOT_FOUND); return; } /* Check if new URI Path is valid */ if (!check_url_fn (uri_path, req_code)) { coap_pdu_set_code(response, COAP_RESPONSE_CODE_NOT_FOUND); coap_delete_string(uri_path); return; } /* * Create a resource to handle the new URI * uri_path will get deleted when the resource is removed */ r = coap_resource_init((coap_str_const_t*)uri_path, COAP_RESOURCE_FLAGS_RELEASE_URI | COAP_RESOURCE_FLAGS_NOTIFY_NON); coap_register_handler(r, COAP_REQUEST_PUT, hnd_put); coap_register_handler(r, COAP_REQUEST_DELETE, hnd_delete); /* We possibly want to Observe the GETs */ coap_resource_set_get_observable(r, 1); coap_register_handler(r, COAP_REQUEST_GET, hnd_get); coap_add_resource(coap_session_get_context(session), r); /* Do the PUT for this first call */ hnd_put(r, session, request, query, response); return; } /* Initialize single Unknown Resource PUT handler */ static void init_resources(coap_context_t *ctx) { coap_resource_t *r; /* Create a resource to handle PUTs to unknown URIs */ r = coap_resource_unknown_init(hnd_unknown_put); /* * Additional handlers can be added - for example * coap_register_handler(r, COAP_REQUEST_POST, hnd_post_unknown); * coap_register_handler(r, COAP_REQUEST_GET, hnd_get_unknown); * coap_register_handler(r, COAP_REQUEST_DELETE, hnd_delete_unknown); */ coap_add_resource(ctx, r); } ---- SEE ALSO -------- *coap_attribute*(3), *coap_context*(3), *coap_observe*(3) and *coap_handler*(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