Common Gateway Interface library (libcgi)#

The libcgi library provides a set of functionalities for handling Common Gateway Interface (CGI) operations in C.

Contents#

General information
Request Method
Authentication Modes
libcgi interface
- Data Structures
- Parameters Management
Using libcgi

General information#

The libcgi library is a helper library designed to facilitate CGI. It provides functions for retrieving request methods, query strings, printing headers, managing URL and multipart parameters, and handling authentication.

Request Method#

The library defines an enumeration for various HTTP request methods:

LIBCGI_METHOD_POST: Indicates a POST request method.
LIBCGI_METHOD_POST_MULTIPART: Indicates a POST request with multipart data.
LIBCGI_METHOD_GET: Indicates a GET request method.
LIBCGI_METHOD_DELETE: Indicates a DELETE request method.
LIBCGI_METHOD_ERROR: Used to indicate an error in determining the request method.

Authentication Modes#

The library also defines an enumeration for authentication modes, currently including:

LIBCGI_AUTH_COOKIE_FILE: Indicates authentication via a cookie file.

libcgi interface#

libcgi_getRequestMethod - Returns the request method used for the current CGI call.

int libcgi_getRequestMethod(void)

libcgi_getQueryString - Returns the query string from the current CGI call.

char *libcgi_getQueryString(void)

libcgi_printCode - Prints the HTTP status code and status message as part of the response header.

void libcgi_printCode(unsigned code, char *status)

libcgi_printHeaders - Prints the HTTP response headers including content type, content disposition, and any additional raw headers.

void libcgi_printHeaders(char *content_type, char *content_disposition, char *filename, char *raw_headers)

libcgi_isLogged - A customizable function to determine if a user is logged in. It can take multiple arguments for validation.

int libcgi_isLogged(int argc, ...)

Data Structures#

libcgi_param_t - Represents a parameter, which could be a part of the URL query string or a part of multipart form data.

typedef struct _libcgi_param {
	struct _libcgi_param *next; //  Pointer to the next parameter in the list
	enum { LIBCGI_PARAM_DEFAULT, LIBCGI_PARAM_FILE } type; // The type of the parameter
	union { // Key of the parameter or filename if the parameter is a file.
		char *key;
		char *filename;
	};
	union { // Value of the parameter or file stream if the parameter is a file.
		char *value;
		FILE *stream;
	};
} libcgi_param_t;

Parameters Management#

libcgi_getUrlParams - Retrieves a linked list of URL parameters.

libcgi_param_t *libcgi_getUrlParams(void)

libcgi_freeUrlParams - Frees the memory allocated for URL parameters.

void libcgi_freeUrlParams(libcgi_param_t *params_head)

libcgi_getMultipartParams - Retrieves a linked list of parameters from a multipart/form-data request. The store_path parameter specifies where to store uploaded files

libcgi_param_t *libcgi_getMultipartParams(char *store_path)

libcgi_freeMultipartParams - Frees the memory allocated for multipart parameters.

void libcgi_freeMultipartParams(libcgi_param_t *params_head)

Using libcgi#

To use functions provided by libcgi please add the library to the LIBS variable in Makefile and include the required header file.