CONF_modules_load_file.pod revision 296341 
1=pod
2
3=head1 NAME
4
5 CONF_modules_load_file, CONF_modules_load - OpenSSL configuration functions
6
7=head1 SYNOPSIS
8
9 #include <openssl/conf.h>
10
11 int CONF_modules_load_file(const char *filename, const char *appname,
12			                unsigned long flags);
13 int CONF_modules_load(const CONF *cnf, const char *appname,
14		               unsigned long flags);
15
16=head1 DESCRIPTION
17
18The function CONF_modules_load_file() configures OpenSSL using file
19B<filename> and application name B<appname>. If B<filename> is NULL
20the standard OpenSSL configuration file is used. If B<appname> is
21NULL the standard OpenSSL application name B<openssl_conf> is used.
22The behaviour can be cutomized using B<flags>.
23
24CONF_modules_load() is idential to CONF_modules_load_file() except it
25reads configuration information from B<cnf>.
26
27=head1 NOTES
28
29The following B<flags> are currently recognized:
30
31B<CONF_MFLAGS_IGNORE_ERRORS> if set errors returned by individual
32configuration modules are ignored. If not set the first module error is
33considered fatal and no further modules are loaded.
34
35Normally any modules errors will add error information to the error queue. If
36B<CONF_MFLAGS_SILENT> is set no error information is added.
37
38If B<CONF_MFLAGS_NO_DSO> is set configuration module loading from DSOs is
39disabled.
40
41B<CONF_MFLAGS_IGNORE_MISSING_FILE> if set will make CONF_load_modules_file()
42ignore missing configuration files. Normally a missing configuration file
43return an error.
44
45B<CONF_MFLAGS_DEFAULT_SECTION> if set and B<appname> is not NULL will use the
46default section pointed to by B<openssl_conf> if B<appname> does not exist.
47
48Applications should call these functions after loading builtin modules using
49OPENSSL_load_builtin_modules(), any ENGINEs for example using
50ENGINE_load_builtin_engines(), any algorithms for example
51OPENSSL_add_all_algorithms() and (if the application uses libssl)
52SSL_library_init().
53
54By using CONF_modules_load_file() with appropriate flags an application can
55customise application configuration to best suit its needs. In some cases the
56use of a configuration file is optional and its absence is not an error: in
57this case B<CONF_MFLAGS_IGNORE_MISSING_FILE> would be set.
58
59Errors during configuration may also be handled differently by different
60applications. For example in some cases an error may simply print out a warning
61message and the application continue. In other cases an application might
62consider a configuration file error as fatal and exit immediately.
63
64Applications can use the CONF_modules_load() function if they wish to load a
65configuration file themselves and have finer control over how errors are
66treated.
67
68=head1 EXAMPLES
69
70Load a configuration file and print out any errors and exit (missing file
71considered fatal):
72
73 if (CONF_modules_load_file(NULL, NULL, 0) <= 0) {
74    fprintf(stderr, "FATAL: error loading configuration file\n");
75    ERR_print_errors_fp(stderr);
76    exit(1);
77 }
78
79Load default configuration file using the section indicated by "myapp",
80tolerate missing files, but exit on other errors:
81
82 if (CONF_modules_load_file(NULL, "myapp",
83                            CONF_MFLAGS_IGNORE_MISSING_FILE) <= 0) {
84    fprintf(stderr, "FATAL: error loading configuration file\n");
85    ERR_print_errors_fp(stderr);
86    exit(1);
87 }
88
89Load custom configuration file and section, only print warnings on error,
90missing configuration file ignored:
91
92 if (CONF_modules_load_file("/something/app.cnf", "myapp",
93                            CONF_MFLAGS_IGNORE_MISSING_FILE) <= 0) {
94    fprintf(stderr, "WARNING: error loading configuration file\n");
95    ERR_print_errors_fp(stderr);
96 }
97
98Load and parse configuration file manually, custom error handling:
99
100 FILE *fp;
101 CONF *cnf = NULL;
102 long eline;
103 fp = fopen("/somepath/app.cnf", "r");
104 if (fp == NULL) {
105    fprintf(stderr, "Error opening configuration file\n");
106    /* Other missing configuration file behaviour */
107 } else {
108    cnf = NCONF_new(NULL);
109    if (NCONF_load_fp(cnf, fp, &eline) == 0) {
110        fprintf(stderr, "Error on line %ld of configuration file\n", eline);
111        ERR_print_errors_fp(stderr);
112        /* Other malformed configuration file behaviour */
113    } else if (CONF_modules_load(cnf, "appname", 0) <= 0) {
114      fprintf(stderr, "Error configuring application\n");
115      ERR_print_errors_fp(stderr);
116      /* Other configuration error behaviour */
117    }
118    fclose(fp);
119    NCONF_free(cnf);
120  }
121
122=head1 RETURN VALUES
123
124These functions return 1 for success and a zero or negative value for
125failure. If module errors are not ignored the return code will reflect the
126return value of the failing module (this will always be zero or negative).
127
128=head1 SEE ALSO
129
130L<conf(5)|conf(5)>, L<OPENSSL_config(3)|OPENSSL_config(3)>,
131L<CONF_free(3)|CONF_free(3)>, L<err(3)|err(3)>
132
133=head1 HISTORY
134
135CONF_modules_load_file and CONF_modules_load first appeared in OpenSSL 0.9.7.
136
137=cut
138