/usr/man2/cat.3/CONF_modules_load_file.3.Z

NAME

        CONF_modules_load_file, CONF_modules_load - OpenSSL configuration functions

SYNOPSIS

        #include <openssl/conf.h>

        int CONF_modules_load_file(const char *filename, const char *appname,
                                               unsigned long flags);
        int CONF_modules_load(const CONF *cnf, const char *appname,
                                      unsigned long flags);

DESCRIPTION

       The function CONF_modules_load_file() configures OpenSSL using file
       filename and application name appname. If filename is NULL the standard
       OpenSSL configuration file is used. If appname is NULL the standard
       OpenSSL application name openssl_conf is used.  The behaviour can be
       cutomized using flags.

       CONF_modules_load() is idential to CONF_modules_load_file() except it
       reads configuration information from cnf.

NOTES

       The following flags are currently recognized:

       CONF_MFLAGS_IGNORE_ERRORS if set errors returned by individual configu-
       ration modules are ignored. If not set the first module error is con-
       sidered fatal and no further modules are loaded.

       Normally any modules errors will add error information to the error
       queue. If CONF_MFLAGS_SILENT is set no error information is added.

       If CONF_MFLAGS_NO_DSO is set configuration module loading from DSOs is
       disabled.

       CONF_MFLAGS_IGNORE_MISSING_FILE if set will make CONF_load_mod-
       ules_file() ignore missing configuration files. Normally a missing con-
       figuration file return an error.

       CONF_MFLAGS_DEFAULT_SECTION if set and appname is not NULL will use the
       default section pointed to by openssl_conf if appname does not exist.

       Applications should call these functions after loading builtin modules
       using OPENSSL_load_builtin_modules(), any ENGINEs for example using
       ENGINE_load_builtin_engines(), any algorithms for example
       OPENSSL_add_all_algorithms() and (if the application uses libssl)
       SSL_library_init().

       By using CONF_modules_load_file() with appropriate flags an application
       can customise application configuration to best suit its needs. In some
       cases the use of a configuration file is optional and its absence is
       not an error: in this case CONF_MFLAGS_IGNORE_MISSING_FILE would be
       set.

       Errors during configuration may also be handled differently by differ-
       ent applications. For example in some cases an error may simply print
       out a warning message and the application continue. In other cases an
       application might consider a configuration file error as fatal and exit
       immediately.

       Applications can use the CONF_modules_load() function if they wish to
       load a configuration file themselves and have finer control over how
       errors are treated.

EXAMPLES

       Load a configuration file and print out any errors and exit (missing
       file considered fatal):

        if (CONF_modules_load_file(NULL, NULL, 0) <= 0) {
           fprintf(stderr, "FATAL: error loading configuration file\n");
           ERR_print_errors_fp(stderr);
           exit(1);
        }

       Load default configuration file using the section indicated by "myapp",
       tolerate missing files, but exit on other errors:

        if (CONF_modules_load_file(NULL, "myapp",
                                   CONF_MFLAGS_IGNORE_MISSING_FILE) <= 0) {
           fprintf(stderr, "FATAL: error loading configuration file\n");
           ERR_print_errors_fp(stderr);
           exit(1);
        }

       Load custom configuration file and section, only print warnings on
       error, missing configuration file ignored:

        if (CONF_modules_load_file("/something/app.cnf", "myapp",
                                   CONF_MFLAGS_IGNORE_MISSING_FILE) <= 0) {
           fprintf(stderr, "WARNING: error loading configuration file\n");
           ERR_print_errors_fp(stderr);
        }

       Load and parse configuration file manually, custom error handling:

        FILE *fp;
        CONF *cnf = NULL;
        long eline;
        fp = fopen("/somepath/app.cnf", "r");
        if (fp == NULL) {
           fprintf(stderr, "Error opening configuration file\n");
           /* Other missing configuration file behaviour */
        } else {
           cnf = NCONF_new(NULL);
           if (NCONF_load_fp(cnf, fp, &eline) == 0) {
               fprintf(stderr, "Error on line %ld of configuration file\n", eline);
               ERR_print_errors_fp(stderr);
               /* Other malformed configuration file behaviour */
           } else if (CONF_modules_load(cnf, "appname", 0) <= 0) {
             fprintf(stderr, "Error configuring application\n");
             ERR_print_errors_fp(stderr);
             /* Other configuration error behaviour */
           }
           fclose(fp);
           NCONF_free(cnf);
         }

RETURN VALUES

       These functions return 1 for success and a zero or negative value for
       failure. If module errors are not ignored the return code will reflect
       the return value of the failing module (this will always be zero or
       negative).

SEE ALSO

       conf(5), OPENSSL_config(3), CONF_free(3), err(3)

HISTORY

       CONF_modules_load_file and CONF_modules_load first appeared in OpenSSL
       0.9.7.

1.0.2t                            2019-09-10         CONF_modules_load_file(3)
See also CONF_modules_load(3)