ulfius

Ulfius API Documentation

Header file

Include file ulfius.h in your source file:

#include <ulfius.h>

On your linker command, add ulfius as a dependency library, e.g. -lulfius for gcc.

Return values

When specified, some functions return U_OK on success, and other values otherwise. U_OK is 0, other values are non-0 values. The defined return value list is the following:

#define U_OK                 0 // No error
#define U_ERROR              1 // Error
#define U_ERROR_MEMORY       2 // Error in memory allocation
#define U_ERROR_PARAMS       3 // Error in input parameters
#define U_ERROR_LIBMHD       4 // Error in libmicrohttpd execution
#define U_ERROR_LIBCURL      5 // Error in libcurl execution
#define U_ERROR_NOT_FOUND    6 // Something was not found

Memory management

Ulfius uses the memory allocation functions malloc/realloc/calloc/free by default, but you can overwrite this and use any other memory allocation functions of your choice. Use Orcania’s functions o_set_alloc_funcs and o_get_alloc_funcs to set and get memory allocation functions.

void o_set_alloc_funcs(o_malloc_t malloc_fn, o_realloc_t realloc_fn, o_free_t free_fn);
void o_get_alloc_funcs(o_malloc_t * malloc_fn, o_realloc_t * realloc_fn, o_free_t * free_fn);

Accessing those functions requires you to directly link your application also against the Orcania library. To do so, add -lorcania to your linking command.

If you use a version of libmicrohttpd older than 0.9.61, you need to set the mhd_response_copy_data = 1 in your _u_instance if you use a memory allocator whose allocated return values may not directly be passed to free() or if you want to make sure all free() will always go via your user-provided free callback.

Data structures allocated have their specific cleanup functions. To free pointer allocated, you should use the function u_free that is intended to use your memory management functions.

/**
 * ulfius_clean_instance
 * 
 * Clean memory allocated by a struct _u_instance *
 */
void ulfius_clean_instance(struct _u_instance * u_instance);

/**
 * ulfius_clean_request
 * clean the specified request's inner elements
 * user must free the parent pointer if needed after clean
 * or use ulfius_clean_request_full
 * return U_OK on success
 */
int ulfius_clean_request(struct _u_request * request);

/**
 * ulfius_clean_response
 * clean the specified response's inner elements
 * user must free the parent pointer if needed after clean
 * or use ulfius_clean_response_full
 * return U_OK on success
 */
int ulfius_clean_response(struct _u_response * response);

/**
 * free the struct _u_map's inner components
 * return U_OK on success
 */
int u_map_clean(struct _u_map * u_map);

/**
 * free data allocated by ulfius functions
 */
void u_free(void * data);

Webservice initialization

Ulfius framework runs as an async task in the background. When initialized, a thread is executed in the background. This thread will listen to the specified port and dispatch the calls to the specified callback functions. Ulfius allows adding and removing new endpoints during the instance execution.

To run a webservice, you must initialize a struct _u_instance and add your endpoints.

Instance structure

The struct _u_instance is defined as:

/**
 * 
 * Structure of an instance
 * 
 * Contains the needed data for an ulfius instance to work
 * 
 * mhd_daemon:             pointer to the libmicrohttpd daemon
 * status:                 status of the current instance, status are U_STATUS_STOP, U_STATUS_RUNNING or U_STATUS_ERROR
 * port:                   port number to listen to
 * network_type:           Listen to ipv4 and or ipv6 connections, values available are U_USE_ALL, U_USE_IPV4 or U_USE_IPV6
 * bind_address:           ipv4 address to listen to (optional)
 * timeout:                Timeout to close the connection because of inactivity between the client and the server
 * nb_endpoints:           Number of available endpoints
 * default_auth_realm:     Default realm on authentication error
 * endpoint_list:          List of available endpoints
 * default_endpoint:       Default endpoint if no other endpoint match the current url
 * default_headers:        Default headers that will be added to all response->map_header
 * max_post_param_size:    maximum size for a post parameter, 0 means no limit, default 0
 * max_post_body_size:     maximum size for the entire post body, 0 means no limit, default 0
 * websocket_handler:      handler for the websocket structure
 * file_upload_callback:   callback function to manage file upload by blocks
 * file_upload_cls:        any pointer to pass to the file_upload_callback function
 * mhd_response_copy_data: to choose between MHD_RESPMEM_MUST_COPY and MHD_RESPMEM_MUST_FREE, only if you use MHD < 0.9.61, 
 *                         otherwise this option is skipped because it's useless
 * check_utf8:             check that all parameters values in the request (url, header and post_body)
 *                         are valid utf8 strings, if a parameter value has non utf8 character, the value
 *                         will be ignored, default 1
 * use_client_cert_auth:   Internal variable use to indicate if the instance uses client certificate authentication
 *                         Do not change this value, available only if websocket support is enabled
 * 
 */
struct _u_instance {
  struct MHD_Daemon          *  mhd_daemon;
  int                           status;
  unsigned int                  port;
  unsigned short                network_type;
  struct sockaddr_in          * bind_address;
  struct sockaddr_in6         * bind_address6;
  unsigned int                  timeout;
  int                           nb_endpoints;
  char                        * default_auth_realm;
  struct _u_endpoint          * endpoint_list;
  struct _u_endpoint          * default_endpoint;
  struct _u_map               * default_headers;
  size_t                        max_post_param_size;
  size_t                        max_post_body_size;
  void                        * websocket_handler;
  int                        (* file_upload_callback) (const struct _u_request * request, 
                                                       const char * key, 
                                                       const char * filename, 
                                                       const char * content_type, 
                                                       const char * transfer_encoding, 
                                                       const char * data, 
                                                       uint64_t off, 
                                                       size_t size, 
                                                       void * cls);
  void                        * file_upload_cls;
  int                           mhd_response_copy_data;
  int                           check_utf8;
#ifndef U_DISABLE_GNUTLS
  int                           use_client_cert_auth;
#endif
};

In the struct _u_instance structure, the element port must be set to the port number you want to listen to, the element bind_address is used if you want to listen only to a specific IP address. The element mhd_daemon is used by the framework, don’t modify it.

You can use the functions ulfius_init_instance, ulfius_init_instance_ipv6 and ulfius_clean_instance to facilitate the manipulation of the structure:

/**
 * ulfius_init_instance
 * 
 * Initialize a struct _u_instance * with default values
 * Binds to IPV4 addresses only
 * port:               tcp port to bind to, must be between 1 and 65535
 * bind_address:       IPv4 address to listen to, optional, the reference is borrowed, the structure isn't copied
 * default_auth_realm: default realm to send to the client on authentication error
 * return U_OK on success
 */
int ulfius_init_instance(struct _u_instance * u_instance, int port, struct sockaddr_in * bind_address, const char * default_auth_realm);

/**
 * ulfius_init_instance_ipv6
 * 
 * Initialize a struct _u_instance * with default values
 * Binds to IPV6 and IPV4 addresses or IPV6 addresses only
 * port:               tcp port to bind to, must be between 1 and 65535
 * bind_address:       IPv6 address to listen to, optional, the reference is borrowed, the structure isn't copied
 * network_type:       Type of network to listen to, values available are U_USE_IPV6 or U_USE_ALL
 * default_auth_realm: default realm to send to the client on authentication error
 * return U_OK on success
 */
int ulfius_init_instance_ipv6(struct _u_instance * u_instance, unsigned int port, struct sockaddr_in6 * bind_address, unsigned short network_type, const char * default_auth_realm);

/**
 * ulfius_clean_instance
 * 
 * Clean memory allocated by a struct _u_instance *
 */
void ulfius_clean_instance(struct _u_instance * u_instance);

Since Ulfius 2.6, you can bind to IPv4 connections, IPv6 or both. By default, ulfius_init_instance binds to IPv4 addresses only. If you want to bind to both IPv4 and IPv6 addresses, use ulfius_init_instance_ipv6 with the value parameter network_type set to U_USE_ALL. If you want to bind to IPv6 addresses only, use ulfius_init_instance_ipv6 with the value parameter network_type set to U_USE_IPV6.

Endpoint structure

The struct _u_endpoint is defined as:

/**
 * 
 * Structure of an endpoint
 * 
 * Contains all informations needed for an endpoint
 * http_method:       http verb (GET, POST, PUT, etc.) in upper case
 * url_prefix:        prefix for the url (optional)
 * url_format:        string used to define the endpoint format
 *                    separate words with /
 *                    to define a variable in the url, prefix it with @ or :
 *                    example: /test/resource/:name/elements
 *                    on an url_format that ends with '*', the rest of the url will not be tested
 * priority:          endpoint priority in descending order (0 is the higher priority)
 * callback_function: a pointer to a function that will be executed each time the endpoint is called
 *                    you must declare the function as described.
 * user_data:         a pointer to a data or a structure that will be available in callback_function
 * 
 */
struct _u_endpoint {
  char       * http_method;
  char       * url_prefix;
  char       * url_format;
  unsigned int priority;
  int       (* callback_function)(const struct _u_request * request, // Input parameters (set by the framework)
                            struct _u_response * response,     // Output parameters (set by the user)
                            void * user_data);
  void       * user_data;
};

Some functions help you facilitate endpoints manipulation:

/**
 * Add a struct _u_endpoint * to the specified u_instance
 * Can be done during the execution of the webservice for injection
 * u_instance: pointer to a struct _u_instance that describe its port and bind address
 * u_endpoint: pointer to a struct _u_endpoint that will be copied in the u_instance endpoint_list
 * return U_OK on success
 */
int ulfius_add_endpoint(struct _u_instance * u_instance, const struct _u_endpoint * u_endpoint);

/**
 * Add a struct _u_endpoint * to the specified u_instance with its values specified
 * Can be done during the execution of the webservice for injection
 * u_instance: pointer to a struct _u_instance that describe its port and bind address
 * http_method:       http verb (GET, POST, PUT, etc.) in upper case
 * url_prefix:        prefix for the url (optional)
 * url_format:        string used to define the endpoint format
 *                    separate words with /
 *                    to define a variable in the url, prefix it with @ or :
 *                    example: /test/resource/:name/elements
 *                    on an url_format that ends with '*', the rest of the url will not be tested
 * priority:          endpoint priority in descending order (0 is the higher priority)
 * callback_function: a pointer to a function that will be executed each time the endpoint is called
 *                    you must declare the function as described.
 * user_data:         a pointer to a data or a structure that will be available in callback_function
 * return U_OK on success
 */
int ulfius_add_endpoint_by_val(struct _u_instance * u_instance,
                               const char * http_method,
                               const char * url_prefix,
                               const char * url_format,
                               uint priority,
                               int (* callback_function)(const struct _u_request * request, // Input parameters (set by the framework)
                                                         struct _u_response * response,     // Output parameters (set by the user)
                                                         void * user_data),
                               void * user_data);

/**
 * Add a struct _u_endpoint * list to the specified u_instance
 * Can be done during the execution of the webservice for injection
 * u_instance: pointer to a struct _u_instance that describe its port and bind address
 * u_endpoint_list: pointer to an array of struct _u_endpoint ending with a ulfius_empty_endpoint() that will be copied in the u_instance endpoint_list
 * return U_OK on success
 */
int ulfius_add_endpoint_list(struct _u_instance * u_instance, const struct _u_endpoint ** u_endpoint_list);

/**
 * Remove a struct _u_endpoint * from the specified u_instance
 * Can be done during the execution of the webservice for injection
 * u_instance: pointer to a struct _u_instance that describe its port and bind address
 * u_endpoint: pointer to a struct _u_endpoint that will be removed in the u_instance endpoint_list
 * The parameters _u_endpoint.http_method, _u_endpoint.url_prefix and _u_endpoint.url_format are strictly compared for the match
 * If no endpoint is found, return U_ERROR_NOT_FOUND
 * return U_OK on success
 */
int ulfius_remove_endpoint(struct _u_instance * u_instance, const struct _u_endpoint * u_endpoint);

/**
 * Remove a struct _u_endpoint * from the specified u_instance
 * using the specified values used to identify an endpoint
 * Can be done during the execution of the webservice for injection
 * u_instance: pointer to a struct _u_instance that describe its port and bind address
 * http_method: http_method used by the endpoint
 * url_prefix: url_prefix used by the endpoint
 * url_format: url_format used by the endpoint
 * The parameters _u_endpoint.http_method, _u_endpoint.url_prefix and _u_endpoint.url_format are strictly compared for the match
 * If no endpoint is found, return U_ERROR_NOT_FOUND
 * return U_OK on success
 */
int ulfius_remove_endpoint_by_val(struct _u_instance * u_instance, const char * http_method, const char * url_prefix, const char * url_format);

/**
 * ulfius_set_default_callback_function
 * Set the default callback function
 * This callback will be called if no endpoint match the url called
 * callback_function: a pointer to a function that will be executed each time the endpoint is called
 *                    you must declare the function as described.
 * user_data:         a pointer to a data or a structure that will be available in the callback function
 * to remove a default callback function, call ulfius_set_default_callback_function with NULL parameter for callback_function
 * return U_OK on success
 */
int ulfius_set_default_callback_function(struct _u_instance * u_instance,
                                         int (* callback_function)(const struct _u_request * request, struct _u_response * response, void * user_data),
                                         void * user_data);

HTTP Method can be an existing or not existing method, or * for any method. You must specify a url_prefix, a url_format or both, callback_function is mandatory, user_data is optional.

If you fill your array of endoints manually, your struct _u_endpoint array MUST end with an empty struct _u_endpoint.

You can manually declare an endpoint or use the dedicated functions as int ulfius_add_endpoint or int ulfius_add_endpoint_by_val. It’s recommended to use the dedicated functions to fill this array though.

If you manipulate the attribute u_instance.endpoint_list, you must end the list with an empty endpoint (see const struct _u_endpoint * ulfius_empty_endpoint()), and you must set the attribute u_instance.nb_endpoints accordingly. Also, you must use dynamically allocated values (malloc) for attributes http_method, url_prefix and url_format.

Multiple callback functions

Ulfius allows multiple callbacks for the same endpoint. This is helpful when you need to execute several actions in sequence, for example check authentication, get resource, set cookie, then gzip response body. That’s also why a priority must be set for each callback.

The priority is in descending order, which means that it starts with 0 (highest priority) and priority decreases when priority number increases. There is no more signification to the priority number, which means you can use any incrementation of your choice.

Warning: Having 2 callback functions with the same priority number will result in an undefined execution order result.

To help passing parameters between callback functions of the same request, the value struct _u_response.shared_data can bse used. But it will not be allocated or freed by the framework, the program using this variable must free by itself.

Multiple urls with similar pattern

If you need to differentiate multiple urls with similar pattern, you can use priorities among multiple callback function.

For example, if you have 2 endpoints with the following patterns:

1- /example/:id 2- /example/findByStatus

You’ll probably need the callback referred in 2- to be called and the callback referred in 1- not when the url called is the exact pattern as in 2-. Nevertheless, you’ll need callback referred in 1- in all the other cases.

In that case, you’ll have to set a higher priority to the endpoint with the url 2- and return its callback function with the value U_CALLBACK_COMPLETE. Remember, if the first callback returns U_CALLBACK_CONTINUE, the second callback will be called afterwards.

int callback_example_find_by_status(const struct _u_request * request, struct _u_response * response, void * user_data) {
  /* do something here... */
  return U_CALLBACK_COMPLETE;
}

int callback_example_by_id(const struct _u_request * request, struct _u_response * response, void * user_data) {
  /* do something else there... */
  return U_CALLBACK_CONTINUE;
}

int main() {
  /* initialize program and instance */
  ulfius_add_endpoint_by_val(instance, "GET", NULL, "/example/:id", 1, &callback_example_by_id, my_user_data);
  ulfius_add_endpoint_by_val(instance, "GET", NULL, "/example/findByStatus", 0, &callback_example_find_by_status, my_user_data);
  /* start instance and run program */
}

Start and stop webservice

Start webservice

The starting point function are ulfius_start_framework, ulfius_start_secure_framework or ulfius_start_secure_ca_trust_framework:

/**
 * ulfius_start_framework
 * Initializes the framework and run the webservice based on the parameters given
 * return truze if no error
 * 
 * u_instance:    pointer to a struct _u_instance that describe its port and bind address
 * return U_OK on success
 */
int ulfius_start_framework(struct _u_instance * u_instance);

/**
 * ulfius_start_secure_framework
 * Initializes the framework and run the webservice based on the parameters given using an HTTPS connection
 * 
 * u_instance:    pointer to a struct _u_instance that describe its port and bind address
 * key_pem:       private key for the server
 * cert_pem:      server certificate
 * return U_OK on success
 */
int ulfius_start_secure_framework(struct _u_instance * u_instance, const char * key_pem, const char * cert_pem);

/**
 * ulfius_start_secure_ca_trust_framework
 * Initializes the framework and run the webservice based on the parameters given using an HTTPS connection
 * And using a root server to authenticate client connections
 * 
 * u_instance:    pointer to a struct _u_instance that describe its port and bind address
 * key_pem:       private key for the server
 * cert_pem:      server certificate
 * root_ca_pem:   client root CA you're willing to trust for this instance
 * return U_OK on success
 */
int ulfius_start_secure_ca_trust_framework(struct _u_instance * u_instance, const char * key_pem, const char * cert_pem, const char * root_ca_pem);

In your program, where you want to start the web server, execute the function ulfius_start_framework(struct _u_instance * u_instance) for a non-secure http connection. Use the function ulfius_start_secure_framework(struct _u_instance * u_instance, const char * key_pem, const char * cert_pem) for a secure https connection, using a valid private key and a valid corresponding server certificate, see openssl documentation for certificate generation. Finally, use the function int ulfius_start_secure_ca_trust_framework(struct _u_instance * u_instance, const char * key_pem, const char * cert_pem, const char * root_ca_pem) to start a secure https connection and be able to authenticate clients with a certificate. Those function accept the previously declared instance as first parameter. You can reuse the same callback function as much as you want for different endpoints. On success, these functions returns U_OK, otherwise an error code.

Note: for security concerns, after running ulfius_start_secure_framework or ulfius_start_secure_ca_trust_framework, you can free the parameters key_pem, cert_pem and root_ca_pem if you want to.

Stop webservice

To stop the webservice, call the following function:

/**
 * ulfius_stop_framework
 * 
 * Stop the webservice
 * u_instance:    pointer to a struct _u_instance that describe its port and bind address
 * return U_OK on success
 */
int ulfius_stop_framework(struct _u_instance * u_instance);

Callback functions management

The callback function is the function executed when a user calls an endpoint managed by your webservice (as defined in your struct _u_endpoint list).

The callback function has the following signature:

int (* callback_function)(const struct _u_request * request, // Input parameters (set by the framework)
                          struct _u_response * response,     // Output parameters (set by the user)
                          void * user_data);

In the callback function definition, the variables request and response will be initialized by the framework, and the user_data variable will be assigned to the user_data defined in your endpoint list definition.

Request structure

The request variable is defined as:

/**
 * 
 * Structure of request parameters
 * 
 * Contains request data
 * http_protocol:                  http protocol used (1.0 or 1.1)
 * http_verb:                      http method (GET, POST, PUT, DELETE, etc.)
 * http_url:                       full url used to call this callback function or full url to call when used in a ulfius_send_http_request
 * url_path:                       url path only used to call this callback function (ex, if http_url is /path/?param=1, url_path is /path/)
 * proxy:                          proxy address to use for outgoing connections, used by ulfius_send_http_request
 * network_type:                   Force connect to ipv4, ipv6 addresses or both, values available are U_USE_ALL, U_USE_IPV4 or U_USE_IPV6
 * check_server_certificate:       check server certificate and hostname, default true, used by ulfius_send_http_request
 * check_server_certificate_flag:  check certificate peer and or server hostname if check_server_certificate is enabled, values available are U_SSL_VERIFY_PEER, U_SSL_VERIFY_HOSTNAME or both
                                   default value is both (U_SSL_VERIFY_PEER|U_SSL_VERIFY_HOSTNAME), used by ulfius_send_http_request
 * check_proxy_certificate:        check proxy certificate and hostname, default true, used by ulfius_send_http_request, requires libcurl >= 7.52
 * check_proxy_certificate_flag:   check certificate peer and or proxy hostname if check_proxy_certificate is enabled, values available are U_SSL_VERIFY_PEER, U_SSL_VERIFY_HOSTNAME or both
                                   default value is both (U_SSL_VERIFY_PEER|U_SSL_VERIFY_HOSTNAME), used by ulfius_send_http_request, requires libcurl >= 7.52
 * ca_path                         specify a path to CA certificates instead of system path, used by ulfius_send_http_request
 * timeout                         connection timeout used by ulfius_send_http_request, default is 0
 * client_address:                 IP address of the client
 * auth_basic_user:                basic authentication username
 * auth_basic_password:            basic authentication password
 * map_url:                        map containing the url variables, both from the route and the ?key=value variables
 * map_header:                     map containing the header variables
 * map_cookie:                     map containing the cookie variables
 * map_post_body:                  map containing the post body variables (if available)
 * binary_body:                    pointer to raw body
 * binary_body_length:             length of raw body
 * callback_position:              position of the current callback function in the callback list, starts at 0
 * client_cert:                    x509 certificate of the client if the instance uses client certificate authentication and the client is authenticated
 *                                 available only if websocket support is enabled
 * client_cert_file:               path to client certificate file for sending http requests with certificate authentication
 *                                 available only if websocket support is enabled
 * client_key_file:                path to client key file for sending http requests with certificate authentication
 *                                 available only if websocket support is enabled
 * client_key_password:            password to unlock client key file
 *                                 available only if websocket support is enabled
 */
struct _u_request {
  char *               http_protocol;
  char *               http_verb;
  char *               http_url;
  char *               url_path;
  char *               proxy;
  unsigned short       network_type;
  int                  check_server_certificate;
  int                  check_server_certificate_flag;
  int                  check_proxy_certificate;
  int                  check_proxy_certificate_flag;
  char *               ca_path;
  unsigned long        timeout;
  struct sockaddr *    client_address;
  char *               auth_basic_user;
  char *               auth_basic_password;
  struct _u_map *      map_url;
  struct _u_map *      map_header;
  struct _u_map *      map_cookie;
  struct _u_map *      map_post_body;
  void *               binary_body;
  size_t               binary_body_length;
  unsigned int         callback_position;
#ifndef U_DISABLE_GNUTLS
  gnutls_x509_crt_t    client_cert;
  char *               client_cert_file;
  char *               client_key_file;
  char *               client_key_password;
#endif
};

Some functions are dedicated to handle the request:

/**
 * ulfius_set_string_body_request
 * Set a string string_body to a request
 * string_body must end with a '\0' character
 * return U_OK on success
 */
int ulfius_set_string_body_request(struct _u_response * request, const char * string_body);

/**
 * ulfius_set_binary_body_request
 * Add a binary binary_body to a request
 * return U_OK on success
 */
int ulfius_set_binary_body_request(struct _u_response * request, const char * binary_body, const size_t length);

/**
 * ulfius_set_empty_body_request
 * Set an empty request body
 * return U_OK on success
 */
int ulfius_set_empty_body_request(struct _u_request * request);

Response structure

The response variable is defined as:

/**
 * 
 * Structure of response parameters
 * 
 * Contains response data that must be set by the user
 * status:               HTTP status code (200, 404, 500, etc)
 * protocol:             HTTP Protocol sent
 * map_header:           map containing the header variables
 * nb_cookies:           number of cookies sent
 * map_cookie:           array of cookies sent
 * auth_realm:           realm to send to the client on authenticationb failed
 * binary_body:          a void * containing a raw binary content
 * binary_body_length:   the length of the binary_body
 * stream_callback:      callback function to stream data in response body
 * stream_callback_free: callback function to free data allocated for streaming
 * stream_size:          size of the streamed data (U_STREAM_SIZE_UNKOWN if unknown)
 * stream_block_size:    size of each block to be streamed, set according to your system
 * stream_user_data:     user defined data that will be available in your callback stream functions
 * websocket_handle:     handle for websocket extension
 * shared_data:          any data shared between callback functions, must be allocated and freed by the callback functions
 * timeout:              Timeout in seconds to close the connection because of inactivity between the client and the server
 * 
 */
struct _u_response {
  long               status;
  char             * protocol;
  struct _u_map    * map_header;
  unsigned int       nb_cookies;
  struct _u_cookie * map_cookie;
  char             * auth_realm;
  void             * binary_body;
  size_t             binary_body_length;
  ssize_t         (* stream_callback) (void * stream_user_data, uint64_t offset, char * out_buf, size_t max);
  void            (* stream_callback_free) (void * stream_user_data);
  uint64_t           stream_size;
  size_t             stream_block_size;
  void             * stream_user_data;
  void             * websocket_handle;
  void *             shared_data;
  unsigned int       timeout;
};

In the response variable set by the framework to the callback function, the structure is initialized with no data.

The user can set the binary_body before the return statement, or no response body at all if no need. If a binary_body is set, its size must be set to binary_body_length. binary_body is free’d by the framework when the response has been sent to the client, so you must use dynamically allocated values. If no status is set, status 200 will be sent to the client.

Some functions are dedicated to handle the response:

/**
 * ulfius_add_header_to_response
 * add a header to the response
 * return U_OK on success
 */
int ulfius_add_header_to_response(struct _u_response * response, const char * key, const char * value);

/**
 * ulfius_set_string_body_response
 * Add a string body to a response
 * body must end with a '\0' character
 * return U_OK on success
 */
int ulfius_set_string_body_response(struct _u_response * response, const uint status, const char * body);

/**
 * ulfius_set_binary_response
 * Add a binary body to a response
 * return U_OK on success
 */
int ulfius_set_binary_response(struct _u_response * response, const uint status, const char * body, const size_t length);

/**
 * ulfius_set_empty_body_response
 * Set an empty response with only a status
 * return U_OK on success
 */
int ulfius_set_empty_body_response(struct _u_response * response, const uint status);

/**
 * ulfius_set_stream_response
 * Set an stream response with a status
 * return U_OK on success
 */
int ulfius_set_stream_response(struct _u_response * response, 
                                const uint status,
                                ssize_t (* stream_callback) (void * stream_user_data, uint64_t offset, char * out_buf, size_t max);
                                void (* stream_callback_free) (void * stream_user_data),
                                uint64_t stream_size,
                                size_t stream_block_size,
                                void * stream_user_data);

/**
 * Set a websocket in the response
 * You must set at least websocket_manager_callback or websocket_incoming_message_callback
 * @Parameters
 * response: struct _u_response to send back the websocket initialization, mandatory
 * websocket_protocol: list of protocols, separated by a comma, or NULL if all protocols are accepted
 * websocket_extensions: list of extensions, separated by a comma, or NULL if all extensions are accepted
 * websocket_manager_callback: callback function called right after the handshake acceptance, optional
 * websocket_manager_user_data: any data that will be given to the websocket_manager_callback, optional
 * websocket_incoming_message_callback: callback function called on each incoming complete message, optional
 * websocket_incoming_user_data: any data that will be given to the websocket_incoming_message_callback, optional
 * websocket_onclose_callback: callback function called right before closing the websocket, must be complete for the websocket to close
 * websocket_onclose_user_data: any data that will be given to the websocket_onclose_callback, optional
 * @Return value: U_OK on success
 */
int ulfius_set_websocket_response(struct _u_response * response,
                                   const char * websocket_protocol,
                                   const char * websocket_extensions, 
                                   void (* websocket_manager_callback) (const struct _u_request * request,
                                                                        struct _websocket_manager * websocket_manager,
                                                                        void * websocket_manager_user_data),
                                   void * websocket_manager_user_data,
                                   void (* websocket_incoming_message_callback) (const struct _u_request * request,
                                                                                 struct _websocket_manager * websocket_manager,
                                                                                 const struct _websocket_message * message,
                                                                                 void * websocket_incoming_user_data),
                                   void * websocket_incoming_user_data,
                                   void (* websocket_onclose_callback) (const struct _u_request * request,
                                                                        struct _websocket_manager * websocket_manager,
                                                                        void * websocket_onclose_user_data),
                                   void * websocket_onclose_user_data);

Callback functions return value

The callback returned value can have the following values:

Except for the return values U_CALLBACK_UNAUTHORIZED and U_CALLBACK_ERROR, the callback return value isn’t useful to specify the response sent back to the client. Use the struct _u_response variable in your callback function to set all values in the HTTP response.

Use JSON in request and response body

In Ulfius 2.0, hard dependency with libjansson has been removed, the jansson library is now optional but enabled by default.

If you want to remove JSON dependency, build Ulfius library using Makefile with the flag JANSSONFLAG=-DU_DISABLE_JANSSON or with CMake with th option -DWITH_WEBSOCKET=off.

$ make JANSSONFLAG=-DU_DISABLE_JANSSON # Makefile
$ cmake -DWITH_WEBSOCKET=off # CMake

if JSON is enabled, the following functions are available in Ulfius:

/**
 * ulfius_get_json_body_request
 * Get JSON structure from the request body if the request is valid
 * In case of an error in getting or parsing JSON data in the request,
 * the structure json_error_t * json_error will be filled with an error
 * message if json_error is not NULL
 */
json_t * ulfius_get_json_body_request(const struct _u_request * request, json_error_t * json_error);

/**
 * ulfius_set_json_body_request
 * Add a json_t body to a request
 * return U_OK on success
 */
int ulfius_set_json_body_request(struct _u_request * request, json_t * body);

/**
 * ulfius_get_json_body_response
 * Get JSON structure from the response body if the request is valid
 * In case of an error in getting or parsing JSON data in the request,
 * the structure json_error_t * json_error will be filled with an error
 * message if json_error is not NULL
 */
json_t * ulfius_get_json_body_response(struct _u_response * response, json_error_t * json_error);

/**
 * ulfius_set_json_body_response
 * Add a json_t body to a response
 * return U_OK on success
 */
int ulfius_set_json_body_response(struct _u_response * response, const uint status, const json_t * body);

The jansson api documentation is available at the following address: Jansson documentation.

Note: According to the JSON RFC section 6, the MIME media type for JSON text is application/json. Thus, if there is no HTTP header specifying JSON content-type, the functions ulfius_get_json_body_request and ulfius_get_json_body_response will return NULL.

Additional functions

In addition with manipulating the raw parameters of the structures, you can use the _u_request and _u_response structures by using specific functions designed to facilitate their use and memory management:

/**
 * ulfius_init_request
 * Initialize a request structure by allocating inner elements
 * return U_OK on success
 */
int ulfius_init_request(struct _u_request * request);

/**
 * ulfius_clean_request
 * clean the specified request's inner elements
 * user must free the parent pointer if needed after clean
 * or use ulfius_clean_request_full
 * return U_OK on success
 */
int ulfius_clean_request(struct _u_request * request);

/**
 * ulfius_clean_request_full
 * clean the specified request and all its elements
 * return U_OK on success
 */
int ulfius_clean_request_full(struct _u_request * request);

/**
 * ulfius_init_response
 * Initialize a response structure by allocating inner elements
 * return U_OK on success
 */
int ulfius_init_response(struct _u_response * response);

/**
 * ulfius_clean_response
 * clean the specified response's inner elements
 * user must free the parent pointer if needed after clean
 * or use ulfius_clean_response_full
 * return U_OK on success
 */
int ulfius_clean_response(struct _u_response * response);

/**
 * ulfius_clean_response_full
 * clean the specified response and all its elements
 * return U_OK on success
 */
int ulfius_clean_response_full(struct _u_response * response);

/**
 * ulfius_copy_response
 * Copy the source response elements into the des response
 * return U_OK on success
 */
int ulfius_copy_response(struct _u_response * dest, const struct _u_response * source);

/**
 * ulfius_clean_cookie
 * clean the cookie's elements
 * return U_OK on success
 */
int ulfius_clean_cookie(struct _u_cookie * cookie);

/**
 * Copy the cookie source elements into dest elements
 * return U_OK on success
 */
int ulfius_copy_cookie(struct _u_cookie * dest, const struct _u_cookie * source);

/**
 * create a new request based on the source elements
 * returned value must be free'd after use
 */
struct _u_request * ulfius_duplicate_request(const struct _u_request * request);

/**
 * create a new response based on the source elements
 * return value must be free'd after use
 */
struct _u_response * ulfius_duplicate_response(const struct _u_response * response);

Memory management

The Ulfius framework will automatically free the variables referenced by the request and responses structures, except for struct _u_response.shared_data, so you must use dynamically allocated values for the response pointers.

Character encoding

You may be careful with characters encoding if you use non UTF8 characters in your application or webservice source code, and especially if you use different encodings in the same application. Ulfius may not work properly.

The map_cookie structure will contain a set of key/values for the cookies. The cookie structure is defined as

/**
 * struct _u_cookie
 * the structure containing the response cookie parameters
 */
struct _u_cookie {
  char * key;
  char * value;
  char * expires;
  uint   max_age;
  char * domain;
  char * path;
  int    secure;
  int    http_only;
  int    same_site;
};

You can use the functions ulfius_add_cookie_to_response or ulfius_add_same_site_cookie_to_response in your callback function to facilitate cookies management. These functions are defined as:

/**
 * ulfius_add_cookie_to_response
 * add a cookie to the cookie map
 * return U_OK on success
 */
int ulfius_add_cookie_to_response(struct _u_response * response, const char * key, const char * value, const char * expires, const uint max_age, 
                                  const char * domain, const char * path, const int secure, const int http_only);

/**
 * ulfius_add_same_site_cookie_to_response
 * add a cookie to the cookie map with a SameSite attribute
 * the same_site parameter must have one of the following values:
 * - U_COOKIE_SAME_SITE_NONE   - No SameSite attribute
 * - U_COOKIE_SAME_SITE_STRICT - SameSite attribute set to 'Strict'
 * - U_COOKIE_SAME_SITE_LAX    - SameSite attribute set to 'Lax'
 * return U_OK on success
 */
int ulfius_add_same_site_cookie_to_response(struct _u_response * response, const char * key, const char * value, const char * expires, const unsigned int max_age,
                                            const char * domain, const char * path, const int secure, const int http_only, const int same_site);

File upload

Ulifius allows file upload to the server. Beware that an uploaded file will be stored in the request object in memory, so uploading large files may dramatically slow the application or even crash it, depending on your system. An uploaded file is stored in the request->map_body structure. You can use u_map_get_length to get the exact length of the file as it may not be a string format.

If you want to limit the size of a post parameter, if you want to limit the file size for example, set the value struct _u_instance.max_post_param_size. Files or post data exceeding this size will be truncated to the size struct _u_instance.max_post_param_size. If this parameter is 0, then no limit is set. Default value is 0.

If you want to handle file upload yourself, you can intercept the file upload process with your own callback function. Before running the webservice with ulfius_start_framework, you must call the function ulfius_set_upload_file_callback_function with a pointer to your file upload callback function. By using this method, the specified callback function will be executed as much as needed with a chunk of the file upload each time.

This function ulfius_set_upload_file_callback_function has the following prototype:

/**
 * ulfius_set_upload_file_callback_function
 * 
 * Set the callback function to handle file upload
 * Used to facilitate large files upload management
 * The callback function file_upload_callback will be called
 * multiple times, with the uploaded file in striped in parts
 * 
 * Warning: If this function is used, all the uploaded files
 * for the instance will be managed via this function, and they
 * will no longer be available in the struct _u_request in the
 * ulfius callback function afterwards.
 * 
 * Thanks to Thad Phetteplace for the help on this feature
 * 
 * u_instance:    pointer to a struct _u_instance that describe its port and bind address
 * file_upload_callback: Pointer to a callback function that will handle all file uploads
 * cls: a pointer that will be passed to file_upload_callback each tim it's called
 */
int ulfius_set_upload_file_callback_function(struct _u_instance * u_instance,
                                             int (* file_upload_callback) (const struct _u_request * request, 
                                                                           const char * key, 
                                                                           const char * filename, 
                                                                           const char * content_type, 
                                                                           const char * transfer_encoding, 
                                                                           const char * data, 
                                                                           uint64_t off, 
                                                                           size_t size, 
                                                                           void * cls),
                                             void * cls);

This callback function will be called before all the other callback functions, and be aware that not all parameters, especially url parameters, will be present during the file upload callback function executions.

See examples/sheep_counter for a file upload example.

Streaming data

If you need to stream data, i.e. send a variable and potentially large amount of data, or if you need to send a chunked response, you can define and use stream_callback_function in the struct _u_response.

Not that if you stream data to the client, any data that was in the response->binary_body will be ignored. You must at least set the function pointer struct _u_response.stream_callback to stream data. Set stream_size to U_STREAM_SIZE_UNKOWN if you don’t know the size of the data you need to send, like in audio stream for example. Set stream_block_size according to you system resources to avoid out of memory errors, also, set stream_callback_free with a pointer to a function that will free values allocated by your stream callback function, as a close() file for example, and finally, you can set stream_user_data to a pointer.

You can use the function ulfius_set_stream_response to set those parameters.

The prototype of the stream_callback function is the following:

ssize_t stream_callback (void * stream_user_data,  // Your predefined user_data
                         uint64_t offset,          // the position of the current data to send
                         char * out_buf,           // The output buffer to fill with data
                         size_t max);              // the max size of data to be put in the out_buf

The return value must be the size of the data put in out_buf.

This function will be called over and over in loop as long as the client has the connection opened.

If you want to close the stream from the server side, return U_STREAM_END in the stream_callback function. If a problem occured, you can close the connection with a U_STREAM_ERROR return value.

While the stream_callback_free function is as simple as:

void stream_callback_free (void * stream_user_data);

Check the application stream_example in the example folder.

Websockets communication

The websocket protocol is defined in the RFC6455. A websocket is a full-duplex communication layer between a server and a client initiated by a HTTP request. Once the websocket handshake is complete between the client and the server, the tcp socket between them is kept open and messages in a specific format can be exchanged. Any side of the socket can send a message to the other side, which allows the server to push messages to the client.

Ulfius implements websocket communication, both server-side and client-side. The following chapter will describe how to create a websocket service or a websocket client by using callback functions. The framework will handle sending and receiving messages with the clients, and your application will deal with high level functions to facilitate the communication process.

Websocket management

During the websocket connection, you can either send messages, read the incoming messages, close the connection, or wait until the connection is closed by the client or by a network problem.

Messages manipulation

A websocket message has the following structure:

/**
 * websocket message structure
 * contains all the data of a websocket message
 * and the timestamp of when it was sent of received
 */
struct _websocket_message {
  time_t  datestamp; // datestamp when the message was transmitted
  uint8_t opcode;    // opcode of the message: U_WEBSOCKET_OPCODE_TEXT, U_WEBSOCKET_OPCODE_BINARY, U_WEBSOCKET_OPCODE_PING, U_WEBSOCKET_OPCODE_PONG
  uint8_t has_mask;  // Flag to specify if the message has a mask
  uint8_t mask[4];   // mask
  size_t  data_len;  // Length of the data payload
  char  * data;      // data payload
};

The different opcode values available are the following:

U_WEBSOCKET_OPCODE_TEXT
U_WEBSOCKET_OPCODE_BINARY
U_WEBSOCKET_OPCODE_CLOSE
U_WEBSOCKET_OPCODE_PING

If you want to send a message to the client, you must use the dedicated functions ulfius_websocket_send_message or ulfius_websocket_send_fragmented_message:

/**
 * Send a message in the websocket
 * Return U_OK on success
 */
int ulfius_websocket_send_message(struct _websocket_manager * websocket_manager,
                                  const uint8_t opcode,
                                  const uint64_t data_len,
                                  const char * data);

/**
 * Send a fragmented message in the websocket
 * each fragment size will be at most fragment_len
 * Return U_OK on success
 */
int ulfius_websocket_send_fragmented_message(struct _websocket_manager * websocket_manager,
                                             const uint8_t opcode,
                                             const uint64_t data_len,
                                             const char * data,
                                             const size_t fragment_len);

To get the first message of the incoming or outcoming if you need to with ulfius_websocket_pop_first_message, this will remove the first message of the list, and return it as a pointer. You must free the message using the function ulfius_clear_websocket_message after use:

/**
 * Return the first message of the message list
 * Return NULL if message_list has no message
 * Returned value must be cleared after use
 */
struct _websocket_message * ulfius_websocket_pop_first_message(struct _websocket_message_list * message_list);

/**
 * Clear data of a websocket message
 */
void ulfius_clear_websocket_message(struct _websocket_message * message);
Fragmented messages limitation in browsers

It seems that some browsers like Firefox or Chromium don’t like to receive fragmented messages, they will close the connection with a fragmented message is received. Use ulfius_websocket_send_fragmented_message with caution then.

Server-side websocket

Open a websocket communication

To start a websocket communication between the client and your application, you must use the dedicated function ulfius_start_websocket_cb with proper values:

/**
 * Set a websocket in the response
 * You must set at least websocket_manager_callback or websocket_incoming_message_callback
 * @Parameters
 * response: struct _u_response to send back the websocket initialization, mandatory
 * websocket_protocol: list of protocols, separated by a comma, or NULL if all protocols are accepted
 * websocket_extensions: list of extensions, separated by a comma, or NULL if all extensions are accepted
 * websocket_manager_callback: callback function called right after the handshake acceptance, optional
 * websocket_manager_user_data: any data that will be given to the websocket_manager_callback, optional
 * websocket_incoming_message_callback: callback function called on each incoming complete message, optional
 * websocket_incoming_user_data: any data that will be given to the websocket_incoming_message_callback, optional
 * websocket_onclose_callback: callback function called right before closing the websocket, must be complete for the websocket to close
 * websocket_onclose_user_data: any data that will be given to the websocket_onclose_callback, optional
 * @Return value: U_OK on success
 */
int ulfius_set_websocket_response(struct _u_response * response,
                                   const char * websocket_protocol,
                                   const char * websocket_extensions, 
                                   void (* websocket_manager_callback) (const struct _u_request * request,
                                                                        struct _websocket_manager * websocket_manager,
                                                                        void * websocket_manager_user_data),
                                   void * websocket_manager_user_data,
                                   void (* websocket_incoming_message_callback) (const struct _u_request * request,
                                                                                 struct _websocket_manager * websocket_manager,
                                                                                 const struct _websocket_message * message,
                                                                                 void * websocket_incoming_user_data),
                                   void * websocket_incoming_user_data,
                                   void (* websocket_onclose_callback) (const struct _u_request * request,
                                                                        struct _websocket_manager * websocket_manager,
                                                                        void * websocket_onclose_user_data),
                                   void * websocket_onclose_user_data);

According to the Websockets RFC, parameters websocket_protocol and websocket_extensions are specific for your application.

In Ulfius Implementation, if you specify a list of protocols as a string of protocol names, separated by a comma (,), Ulfius framework will check each one and see if they match the list of protocols specified by the client. The resulting protocol list will be sent back to the client. Likewise, the websocket extension is specific to your application, you can specify a list of websocket extension separated by a semicolon (;).

If no protocol match your list, the connection will be closed by the framework and will return an error 400 to the client. If you set a NULL value for the protocol and/or the extension, Ulfius will accept any protocols and/or extension sent by the client.

3 callback functions are available for the websocket implementation:

You must specify at least one of the callback functions between websocket_manager_callback or websocket_incoming_message_callback.

When the function ulfius_stop_framework is called, it will wait for all running websockets to end by themselves, there is no force close. So if you have a websocket_manager_callback function running, you MUST end this function in order to make a clean stop of the http daemon.

For each of these callback function, you can specify a *_user_data pointer containing any data you need.

Close a websocket communication

To close a websocket communication from the server, you can do one of the following:

If no websocket_manager_callback is specified, you can send a U_WEBSOCKET_OPCODE_CLOSE in the websocket_incoming_message_callback function when you need, or call the function ulfius_websocket_send_close_signal.

If a callback function websocket_onclose_callback has been specified, this function will be executed on every case at the end of the websocket connection.

If the websocket handshake hasn’t been correctly completed or if an error appears during the handshake connection, the callback websocket_onclose_callback will be called anyway, even if the callback functions websocket_manager_callback or websocket_incoming_message_callback are skipped due to no websocket connection. This is to allow the calling program to close opened resources or clean allocated memory. Beware that in this specific case, the parameter struct _websocket_manager * websocket_manager may be NULL.

Websocket status

The following functions allow the application to know if the the websocket is still open, to enforce closing the websocket or to wait until the websocket is closed by the client:

/**
 * Sets the websocket in closing mode
 * The websocket will not necessarily be closed at the return of this function,
 * it will process through the end of the `websocket_manager_callback`
 * and the `websocket_onclose_callback` calls first.
 * return U_OK on success
 * or U_ERROR on error
 */
int ulfius_websocket_send_close_signal(struct _websocket_manager * websocket_manager);

/**
 * Returns the status of the websocket connection
 * Returned values can be U_WEBSOCKET_STATUS_OPEN or U_WEBSOCKET_STATUS_CLOSE
 * wether the websocket is open or closed, or U_WEBSOCKET_STATUS_ERROR on error
 */
int ulfius_websocket_status(struct _websocket_manager * websocket_manager);

/**
 * Wait until the websocket connection is closed or the timeout in milliseconds is reached
 * if timeout is 0, no timeout is set
 * Returned values can be U_WEBSOCKET_STATUS_OPEN or U_WEBSOCKET_STATUS_CLOSE
 * wether the websocket is open or closed, or U_WEBSOCKET_STATUS_ERROR on error
 */
int ulfius_websocket_wait_close(struct _websocket_manager * websocket_manager, unsigned int timeout);

Client-side websocket

Ulfius allows to create a websocket connection as a client. The behavior is quite similar to the server-side websocket. The application will open a websocket connection specified by a struct _u_request, and a set of callback functions to manage the websocket once connected.

Prepare the request

You can manually fill the struct _u_request with your parameters or use the dedicated function ulfius_set_websocket_request:

/**
 * Set values for a struct _u_request to open a websocket
 * request must be previously initialized
 * Return U_OK on success
 */
int ulfius_set_websocket_request(struct _u_request * request,
                                 const char * url,
                                 const char * websocket_protocol,
                                 const char * websocket_extensions);

The url specified must have one of the following form:

The websocket_protocol and websocket_extensions values are optional. To specify multiple protocol, you must separate them with the comma , character. To specify multiple extensions, you must separate them with the semicolon ; character.

You can also specify additional headers or cookies to the request.

Any body parameter or body raw value will be ignored, the header Content-Length will be set to 0.

The header User-Agent value will be Ulfius Websocket Client Framework, feel free to modify it afterwards if you need.

Opening the websocket connection

Once the request is completed, you can open the websocket connection with ulfius_open_websocket_client_connection:

/**
 * Open a websocket client connection
 * Return U_OK on success
 * @parameters
 * struct _u_request * request: request used to specify the input parameters
 * websocket_manager_callback: main websocket callback function
 * websocket_manager_user_data: a pointer that will be available in websocket_manager_callback
 * websocket_incoming_message_callback: callback function that will be called each time a message is received
 * websocket_incoming_user_data: a pointer that will be available in websocket_incoming_message_callback
 * websocket_onclose_callback: callback function that will be called right after the websocket is closed
 * websocket_onclose_user_data: a pointer that will be available in websocket_onclose_callback
 * websocket_client_handler: The handler for the websocket
 *
 */
int ulfius_open_websocket_client_connection(struct _u_request * request,
                                            void (* websocket_manager_callback) (const struct _u_request * request,
                                                                                 struct _websocket_manager * websocket_manager,
                                                                                 void * websocket_manager_user_data),
                                            void * websocket_manager_user_data,
                                            void (* websocket_incoming_message_callback) (const struct _u_request * request,
                                                                                          struct _websocket_manager * websocket_manager,
                                                                                          const struct _websocket_message * message,
                                                                                          void * websocket_incoming_user_data),
                                            void * websocket_incoming_user_data,
                                            void (* websocket_onclose_callback) (const struct _u_request * request,
                                                                                 struct _websocket_manager * websocket_manager,
                                                                                 void * websocket_onclose_user_data),
                                            void * websocket_onclose_user_data,
                                            struct _websocket_client_handler * websocket_client_handler);

If the websocket connection is established, U_OK will be returned and the websocket connection will be executed in a separate thread.

Closing a websocket communication

To close a websocket communication, you can do one of the following:

Websocket status

The following functions allow the application to know if the the websocket is still open, to enforce closing the websocket or to wait until the websocket is closed by the server:

/**
 * Send a close signal to the websocket
 * return U_OK when the signal is sent
 * or U_ERROR on error
 */
int ulfius_websocket_client_connection_send_close_signal(struct _websocket_client_handler * websocket_client_handler);

/**
 * Closes a websocket client connection
 * return U_OK when the websocket is closed
 * or U_ERROR on error
 */
int ulfius_websocket_client_connection_close(struct _websocket_client_handler * websocket_client_handler);

/**
 * Returns the status of the websocket client connection
 * Returned values can be U_WEBSOCKET_STATUS_OPEN or U_WEBSOCKET_STATUS_CLOSE
 * wether the websocket is open or closed, or U_WEBSOCKET_STATUS_ERROR on error
 */
int ulfius_websocket_client_connection_status(struct _websocket_client_handler * websocket_client_handler);

/**
 * Wait until the websocket client connection is closed or the timeout in milliseconds is reached
 * if timeout is 0, no timeout is set
 * Returned values can be U_WEBSOCKET_STATUS_OPEN or U_WEBSOCKET_STATUS_CLOSE
 * wether the websocket is open or closed, or U_WEBSOCKET_STATUS_ERROR on error
 */
int ulfius_websocket_client_connection_wait_close(struct _websocket_client_handler * websocket_client_handler, unsigned int timeout);

Outgoing request functions

Ulfius allows output functions to send HTTP or SMTP requests. These functions use libcurl. You can disable these functions by appending the argument CURLFLAG=-DU_DISABLE_CURL when you build the library with Makefile or by disabling the flag in CMake build:

$ make CURLFLAG=-DU_DISABLE_CURL # Makefile
$ cmake -DWITH_CURL=off # CMake

Send HTTP request API

The functions int ulfius_send_http_request(const struct _u_request * request, struct _u_response * response) and int ulfius_send_http_streaming_request(const struct _u_request * request, struct _u_response * response, size_t (* write_body_function)(void * contents, size_t size, size_t nmemb, void * user_data), void * write_body_data) are based on libcurl api.

They allow to send an HTTP request with the parameters specified by the _u_request structure. Use the parameter _u_request.http_url to specify the distant url to call.

You can fill the maps in the _u_request structure with parameters, they will be used to build the request. Note that if you fill _u_request.map_post_body with parameters, the content-type application/x-www-form-urlencoded will be use to encode the data.

The response parameters is stored into the _u_response structure. If you specify NULL for the response structure, the http call will still be made but no response details will be returned. If you use ulfius_send_http_request, the response body will be stored in the parameter response->*body*.

If you use ulfius_send_http_streaming_request, the response body will be available in the write_body_function specified in the call. The ulfius_send_http_streaming_request can be used for streaming data or large response, or if you need to receive a chenked response from the server.

Return value is U_OK on success.

This functions are defined as:

/**
 * ulfius_send_http_request
 * Send a HTTP request and store the result into a _u_response
 * return U_OK on success
 */
int ulfius_send_http_request(const struct _u_request * request, struct _u_response * response);

/**
 * ulfius_send_http_streaming_request
 * Send a HTTP request and store the result into a _u_response
 * Except for the body which will be available using write_body_function in the write_body_data
 * return U_OK on success
 */
int ulfius_send_http_streaming_request(const struct _u_request * request, 
                                       struct _u_response * response, 
                                       size_t (* write_body_function)(void * contents, 
                                                                      size_t size, 
                                                                      size_t nmemb, 
                                                                      void * user_data), 
                                       void * write_body_data);

Send SMTP request API

The function ulfius_send_smtp_email is used to send emails using a smtp server. It is based on libcurl API.

It’s used to send raw emails via a smtp server.

This function is defined as:

/**
 * Send an email
 * host: smtp server host name
 * port: tcp port number (optional, 0 for default)
 * use_tls: true if the connection is tls secured
 * verify_certificate: true if you want to disable the certificate verification on a tls server
 * user: connection user name (optional, NULL: no user name)
 * password: connection password (optional, NULL: no password)
 * from: from address (mandatory)
 * to: to recipient address (mandatory)
 * cc: cc recipient address (optional, NULL: no cc)
 * bcc: bcc recipient address (optional, NULL: no bcc)
 * subject: email subject (mandatory)
 * mail_body: email body (mandatory)
 * return U_OK on success
 */
int ulfius_send_smtp_email(const char * host, 
                           const int port, 
                           const int use_tls, 
                           const int verify_certificate, 
                           const char * user, 
                           const char * password, 
                           const char * from, 
                           const char * to, 
                           const char * cc, 
                           const char * bcc, 
                           const char * subject, 
                           const char * mail_body);

struct _u_map API

The struct _u_map is a simple key/value mapping API used in the requests and the response for setting parameters. The available functions to use this structure are:

/**
 * initialize a struct _u_map
 * this function MUST be called after a declaration or allocation
 * return U_OK on success
 */
int u_map_init(struct _u_map * map);

/**
 * free the struct _u_map's inner components
 * return U_OK on success
 */
int u_map_clean(struct _u_map * u_map);

/**
 * free the struct _u_map and its components
 * return U_OK on success
 */
int u_map_clean_full(struct _u_map * u_map);

/**
 * free an enum return by functions u_map_enum_keys or u_map_enum_values
 * return U_OK on success
 */
int u_map_clean_enum(char ** array);

/**
 * returns an array containing all the keys in the struct _u_map
 * return an array of char * ending with a NULL element
 */
const char ** u_map_enum_keys(const struct _u_map * u_map);

/**
 * returns an array containing all the values in the struct _u_map
 * return an array of char * ending with a NULL element
 */
const char ** u_map_enum_values(const struct _u_map * u_map);

/**
 * return true if the sprcified u_map contains the specified key
 * false otherwise
 * search is case sensitive
 */
int u_map_has_key(const struct _u_map * u_map, const char * key);

/**
 * return true if the sprcified u_map contains the specified value
 * false otherwise
 * search is case sensitive
 */
int u_map_has_value(const struct _u_map * u_map, const char * value);

/**
 * return true if the sprcified u_map contains the specified value up until the specified length
 * false otherwise
 * search is case sensitive
 */
int u_map_has_value_binary(const struct _u_map * u_map, const char * value, size_t length);

/**
 * return true if the sprcified u_map contains the specified key
 * false otherwise
 * search is case insensitive
 */
int u_map_has_key_case(const struct _u_map * u_map, const char * key);

/**
 * return true if the sprcified u_map contains the specified value
 * false otherwise
 * search is case insensitive
 */
int u_map_has_value_case(const struct _u_map * u_map, const char * value);

/**
 * add the specified key/value pair into the specified u_map
 * if the u_map already contains a pair with the same key, replace the value
 * return U_OK on success
 */
int u_map_put(struct _u_map * u_map, const char * key, const char * value);

/**
 * add the specified key/binary value pair into the specified u_map
 * if the u_map already contains a pair with the same key,
 * replace the value at the specified offset with the specified length
 * return U_OK on success
 */
int u_map_put_binary(struct _u_map * u_map, const char * key, const char * value, uint64_t offset, size_t length);

/**
 * get the value length corresponding to the specified key in the u_map
 * return -1 if no match found
 * search is case sensitive
 */
size_t u_map_get_length(const struct _u_map * u_map, const char * key);

/**
 * get the value length corresponding to the specified key in the u_map
 * return -1 if no match found
 * search is case insensitive
 */
size_t u_map_get_case_length(const struct _u_map * u_map, const char * key);

/**
 * get the value corresponding to the specified key in the u_map
 * return NULL if no match found
 * search is case sensitive
 */
const char * u_map_get(const struct _u_map * u_map, const char * key);

/**
 * get the value corresponding to the specified key in the u_map
 * return NULL if no match found
 * search is case insensitive
 */
const char * u_map_get_case(const struct _u_map * u_map, const char * key);

/**
 * remove an pair key/value that has the specified key
 * return U_OK on success, U_NOT_FOUND if key was not found, error otherwise
 */
int u_map_remove_from_key(struct _u_map * u_map, const char * key);

/**
 * remove all pairs key/value that has the specified key (case insensitive search)
 * return U_OK on success, U_NOT_FOUND if key was not found, error otherwise
 */
int u_map_remove_from_key_case(struct _u_map * u_map, const char * key);

/**
 * remove all pairs key/value that has the specified value
 * return U_OK on success, U_NOT_FOUND if key was not found, error otherwise
 */
int u_map_remove_from_value(struct _u_map * u_map, const char * value);

/**
 * remove all pairs key/value that has the specified value (case insensitive search)
 * return U_OK on success, U_NOT_FOUND if key was not found, error otherwise
 */
int u_map_remove_from_value_case(struct _u_map * u_map, const char * value);

/**
 * remove all pairs key/value that has the specified value up until the specified length
 * return U_OK on success, U_NOT_FOUND if key was not found, error otherwise
 */
int u_map_remove_from_value_binary(struct _u_map * u_map, const char * key, size_t length);

/**
 * remove the pair key/value at the specified index
 * return U_OK on success, U_NOT_FOUND if index is out of bound, error otherwise
 */
int u_map_remove_at(struct _u_map * u_map, const int index);

/**
 * Create an exact copy of the specified struct _u_map
 * return a reference to the copy, NULL otherwise
 * returned value must be free'd after use
 */
struct _u_map * u_map_copy(const struct _u_map * source);

/**
 * Copy all key/values pairs of source into target
 * If key is already present in target, it's overwritten
 * return U_OK on success, error otherwise
 */
int u_map_copy_into(const struct _u_map * source, struct _u_map * target);

/**
 * Return the number of key/values pair in the specified struct _u_map
 * Return -1 on error
 */
int u_map_count(const struct _u_map * source);

What’s new in Ulfius 2.6?

Add IPv6 support. Add struct _u_request->callback_position to know the position of the current callback in the callback list.

What’s new in Ulfius 2.5?

Add option to ignore non utf8 strings in incoming requests. Allow client certificate authentication

What’s new in Ulfius 2.4?

Improve websocket service features with lots of bugfixes and add the possibility to send a fragmented message.

Add websocket client functionality. Allow to create a websocket client connection and exchange messages with the websocket service. In http:///ws:// non-secure mode or https:///wss:// secure mode.

Add a command-line websocket client: uwsc.

What’s new in Ulfius 2.3?

Not much on the API, a lot on the build process. Install via CMake script.

What’s new in Ulfius 2.2?

Allow to use your own callback function when uploading files with ulfius_set_upload_file_callback_function, so a large file can be uploaded, even with the option struct _u_instance.max_post_param_size set.

What’s new in Ulfius 2.1?

I know it wasn’t long since Ulfius 2.0 was released. But after some review and tests, I realized some adjustments had to be made to avoid bugs and to clean the framework a little bit more.

Some of the adjustments made in the new release:

The minor version number has been incremented, from 2.0 to 2.1 because some of the changes may require changes in your own code.

What’s new in Ulfius 2.0?

Ulfius 2.0 brings several changes that make the library incompatible with Ulfius 1.0.x branch. The goal of making Ulfius 2.0 is to make a spring cleaning of some functions, remove what is apparently useless, and should bring bugs and memory loss. The main new features are multiple callback functions and websockets implementation.

Multiple callback functions

Instead of having an authentication callback function, then a main callback function, you can now have as much callback functions as you want for the same endpoint. A priority number has been added in the struct _u_endpoint and the auth_callback function and its dependencies have been removed.

For example, let’s say you have the following endpoints defined:

Then if the client calls the url GET /api/potato/myPotato, the following callback functions will be called in that order:

Warning: In this example, the url parameter myPotato will be availabe only in the potato_get_callback function, because the other endpoints did not defined a url parameter after /potato.

If you need to communicate between callback functions for any purpose, you can use the new parameter struct _u_response.shared_data. This is a void * pointer initialized to NULL. If you use it, remember to free it after use, because the framework won’t.

Keep only binary_body in struct _u_request and struct _u_response

the values string_body and json_body have been removed from the structures struct _u_request and struct _u_response. This may be painless in the response if you used only the functions ulfius_set_xxx_body_response. Otherwise, you should make small arrangements to your code.

Websocket service

Ulfius now allows websockets communication between the client and the server. Check the API.md file for implementation details.

Using websocket requires libgnutls. It also requires a recent version of Libmicrohttpd, at least 0.9.53.

If you dont need or can’t use this feature, you can disable it by adding the option WEBSOCKETFLAG=-DU_DISABLE_WEBSOCKET to the make command when you build Ulfius:

$ make WEBSOCKETFLAG=-DU_DISABLE_WEBSOCKET

Remove libjansson and libcurl hard dependency

In Ulfius 1.0, libjansson and libcurl were mandatory to build the library, but their usage was not in the core of the framework. Although they can be very useful, so the dependency is now optional.

They are enabled by default, but if you don’t need them, you can disable them when you build Ulfius library.

libjansson dependency

This dependency allows to use the following functions:

/**
 * ulfius_get_json_body_request
 * Get JSON structure from the request body if the request is valid
 */
json_t * ulfius_get_json_body_request(const struct _u_request * request, json_error_t * json_error);

/**
 * ulfius_set_json_body_request
 * Add a json_t body to a request
 * return U_OK on success
 */
int ulfius_set_json_body_request(struct _u_request * request, json_t * body);

/**
 * ulfius_set_json_body_response
 * Add a json_t body to a response
 * return U_OK on success
 */
int ulfius_set_json_body_response(struct _u_response * response, const uint status, const json_t * body);

/**
 * ulfius_get_json_body_response
 * Get JSON structure from the response body if the request is valid
 */
json_t * ulfius_get_json_body_response(struct _u_response * response, json_error_t * json_error);

If you want to disable these functions, append JANSSONFLAG=-DU_DISABLE_JANSSON when you build Ulfius library.

$ git clone https://github.com/babelouest/ulfius.git
$ cd ulfius/
$ git submodule update --init
$ make JANSSONFLAG=-DU_DISABLE_JANSSON
$ sudo make install

libcurl dependency

This dependency allows to use the following functions:

/**
 * ulfius_send_http_request
 * Send a HTTP request and store the result into a _u_response
 * return U_OK on success
 */
int ulfius_send_http_request(const struct _u_request * request, struct _u_response * response);

/**
 * ulfius_send_http_streaming_request
 * Send a HTTP request and store the result into a _u_response
 * Except for the body which will be available using write_body_function in the write_body_data
 * return U_OK on success
 */
int ulfius_send_http_streaming_request(const struct _u_request * request, struct _u_response * response, size_t (* write_body_function)(void * contents, size_t size, size_t nmemb, void * user_data), void * write_body_data);

/**
 * ulfius_send_smtp_email
 * Send an email using libcurl
 * email is plain/text and UTF8 charset
 * host: smtp server host name
 * port: tcp port number (optional, 0 for default)
 * use_tls: true if the connection is tls secured
 * verify_certificate: true if you want to disable the certificate verification on a tls server
 * user: connection user name (optional, NULL: no user name)
 * password: connection password (optional, NULL: no password)
 * from: from address (mandatory)
 * to: to recipient address (mandatory)
 * cc: cc recipient address (optional, NULL: no cc)
 * bcc: bcc recipient address (optional, NULL: no bcc)
 * subject: email subject (mandatory)
 * mail_body: email body (mandatory)
 * return U_OK on success
 */
int ulfius_send_smtp_email(const char * host, 
                            const int port, 
                            const int use_tls, 
                            const int verify_certificate, 
                            const char * user, 
                            const char * password, 
                            const char * from, 
                            const char * to, 
                            const char * cc, 
                            const char * bcc, 
                            const char * subject, 
                            const char * mail_body);

If you want to disable these functions, append CURLFLAG=-DU_DISABLE_CURL when you build Ulfius library.

$ git clone https://github.com/babelouest/ulfius.git
$ cd ulfius/
$ git submodule update --init
$ make CURLFLAG=-DU_DISABLE_CURL
$ sudo make install

If you wan to disable libjansson and libcurl, you can append both parameters.

$ git clone https://github.com/babelouest/ulfius.git
$ cd ulfius/
$ git submodule update --init
$ make CURLFLAG=-DU_DISABLE_CURL JANSSONFLAG=-DU_DISABLE_JANSSON
$ sudo make install

Ready-to-use callback functions

You can find some ready-to-use callback functions in the folder example_callbacks.

Update existing programs from Ulfius 2.0 to 2.1

Update existing programs from Ulfius 1.x to 2.0

If you already have programs that use Ulfius 1.x and want to update them to the brand new fresh Ulfius 2.0, it may require the following minor changes.

Endpoints definitions

Endpoints structure have changed, ulfius_add_endpoint_by_val now requires only one callback function, but requires a priority number.

If you don’t use authentication callback functions, you can simply remove the NULL, NULL, NULL parameters corresponding to the former authentication callback function pointer, the authentication callback user data, and the realm value. Then add any number as a priority, 0 for example.

If you use authentication callback functions, split your ulfius_add_endpoint_by_val call in 2 separate calls, one for the authentication function, one for the main callback function. For example:

// An Ulfius 1.x call
ulfius_add_endpoint_by_val(&instance, "GET", "/", NULL, &auth_callback, my_auth_data, "my realm", &main_callback, my_main_data);

// The same behaviour with Ulfius 2.0
ulfius_add_endpoint_by_val(&instance, "GET", "/", NULL, 0, &auth_callback, my_auth_data);
ulfius_add_endpoint_by_val(&instance, "GET", "/", NULL, 1, &main_callback, my_main_data);
// In this case, the realm value "my realm" must be specified in the response

Callback return value

The return value for the callback functions must be adapted, instead of U_OK, U_ERROR or U_ERROR_UNAUTHORIZED, you must use one of the following:

#define U_CALLBACK_CONTINUE     0 // Will replace U_OK
#define U_CALLBACK_COMPLETE     1
#define U_CALLBACK_UNAUTHORIZED 2 // Will replace U_ERROR_UNAUTHORIZED
#define U_CALLBACK_ERROR        3 // Will replace U_ERROR

If you want more details on the multiple callback functions, check the documentation.

Other functions may have change their name or signature, check the documentation for more information.