NAME
UI_new,
UI_new_method, UI_free,
UI_add_input_string,
UI_dup_input_string,
UI_add_verify_string,
UI_dup_verify_string,
UI_add_input_boolean,
UI_dup_input_boolean,
UI_add_info_string,
UI_dup_info_string,
UI_add_error_string,
UI_dup_error_string,
UI_construct_prompt,
UI_add_user_data,
UI_get0_user_data,
UI_get0_result, UI_process,
UI_ctrl,
UI_set_default_method,
UI_get_default_method,
UI_get_method,
UI_set_method, UI_OpenSSL
— New User Interface
SYNOPSIS
#include
<openssl/ui.h>
UI *
UI_new(void);
UI *
UI_new_method(const UI_METHOD
*method);
void
UI_free(UI *ui);
int
UI_add_input_string(UI *ui,
const char *prompt, int flags,
char *result_buf, int minsize,
int maxsize);
int
UI_dup_input_string(UI *ui,
const char *prompt, int flags,
char *result_buf, int minsize,
int maxsize);
int
UI_add_verify_string(UI *ui,
const char *prompt, int flags,
char *result_buf, int minsize,
int maxsize, const char
*test_buf);
int
UI_dup_verify_string(UI *ui,
const char *prompt, int flags,
char *result_buf, int minsize,
int maxsize, const char
*test_buf);
int
UI_add_input_boolean(UI *ui,
const char *prompt, const char
*action_desc, const char *ok_chars,
const char *cancel_chars, int
flags, char *result_buf);
int
UI_dup_input_boolean(UI *ui,
const char *prompt, const char
*action_desc, const char *ok_chars,
const char *cancel_chars, int
flags, char *result_buf);
int
UI_add_info_string(UI *ui,
const char *text);
int
UI_dup_info_string(UI *ui,
const char *text);
int
UI_add_error_string(UI *ui,
const char *text);
int
UI_dup_error_string(UI *ui,
const char *text);
/* These are the possible flags. They can be
OR'ed together. */
#define UI_INPUT_FLAG_ECHO 0x01
#define UI_INPUT_FLAG_DEFAULT_PWD 0x02
char *
UI_construct_prompt(UI
*ui_method, const char *object_desc,
const char *object_name);
void *
UI_add_user_data(UI *ui,
void *user_data);
void *
UI_get0_user_data(UI *ui);
const char *
UI_get0_result(UI *ui,
int i);
int
UI_process(UI *ui);
int
UI_ctrl(UI *ui,
int cmd, long i,
void *p, void (*f)());
#define UI_CTRL_PRINT_ERRORS 1
#define UI_CTRL_IS_REDOABLE 2
void
UI_set_default_method(const UI_METHOD
*meth);
const UI_METHOD *
UI_get_default_method(void);
const UI_METHOD *
UI_get_method(UI *ui);
const UI_METHOD *
UI_set_method(UI *ui,
const UI_METHOD *meth);
UI_METHOD *
UI_OpenSSL(void);
DESCRIPTION
UI stands for User Interface, and is a general purpose set of routines to prompt the user for text-based information. Through user-written methods (see UI_create_method(3)), prompting can be done in any way imaginable, be it plain text prompting, through dialog boxes or from a cell phone.
All the functions work through a context of the type UI. This context contains all the information needed to prompt correctly as well as a reference to a UI_METHOD, which is an ordered vector of functions that carry out the actual prompting.
The first thing to do is to create a
UI with
UI_new() or
UI_new_method(), then add information to it with the
UI_add_*() or UI_dup_*()
functions. Also, user-defined random data can be passed down to the
underlying method through calls to
UI_add_user_data(). The default UI method doesn't
care about these data, but other methods might. Finally, use
UI_process() to actually perform the prompting and
UI_get0_result() to find the result to the
prompt.
A UI can contain more than one
prompt, which are performed in the given sequence. Each prompt gets an index
number which is returned by the
UI_add_*()
and
UI_dup_*()
functions, and has to be used to get the corresponding result with
UI_get0_result().
The functions are as follows:
UI_new()
creates a new UI using the default UI method. When
done with this UI, it should be freed using
UI_free().
UI_new_method()
creates a new UI using the given UI method. When done
with this UI, it should be freed using
UI_free().
UI_OpenSSL()
returns the built-in UI method (note: not necessarily the default one, since
the default can be changed. See further on). This method is the most
machine/OS dependent part of OpenSSL and normally generates the most
problems when porting.
UI_free()
removes ui from memory, along with all other pieces of
memory that are connected to it, like duplicated input strings, results and
others. If ui is a NULL
pointer, no action occurs.
UI_add_input_string()
and
UI_add_verify_string()
add a prompt to ui, as well as flags and a result
buffer and the desired minimum and maximum sizes of the result, not counting
the final NUL character. The given information is used to prompt for
information, for example a password, and to verify a password (i.e. having
the user enter it twice and check that the same string was entered twice).
UI_add_verify_string() takes an extra argument that
should be a pointer to the result buffer of the input string that it's
supposed to verify, or verification will fail.
UI_add_input_boolean()
adds a prompt to ui that's supposed to be answered in
a boolean way, with a single character for yes and a different character for
no. A set of characters that can be used to cancel the prompt is given as
well. The prompt itself is really divided in two, one part being the
descriptive text (given through the prompt argument)
and one describing the possible answers (given through the
action_desc argument).
UI_add_info_string()
and
UI_add_error_string()
add strings that are shown at the same time as the prompt for extra
information or to show an error string. The difference between the two is
only conceptual. With the builtin method, there's no technical difference
between them. Other methods may make a difference between them, however.
The flags currently supported are
UI_INPUT_FLAG_ECHO, which is relevant for
UI_add_input_string()
and will have the users response be echoed (when prompting for a password,
this flag should obviously not be used), and
UI_INPUT_FLAG_DEFAULT_PWD, which means that a
default password of some sort will be used (completely depending on the
application and the UI method).
UI_dup_input_string(),
UI_dup_verify_string(),
UI_dup_input_boolean(),
UI_dup_info_string(),
and
UI_dup_error_string()
are basically the same as their UI_add_*()
counterparts, except that they make their own copies of all strings.
UI_construct_prompt()
is a helper function that can be used to create a prompt from two pieces of
information: a description and a name. The default constructor (if there is
none provided by the method used) creates a string "Enter
description
for
name:".
With the description "pass phrase" and the file name
"foo.key", that becomes "Enter pass phrase for
foo.key:". Other methods may create whatever string and may include
encodings that will be processed by the other method functions.
UI_add_user_data()
adds a user data pointer for the method to use at any time. The builtin UI
method doesn't care about this info. Note that several calls to this
function doesn't add data - the previous blob is replaced with the one given
as argument.
UI_get0_user_data()
retrieves the data that has last been given to the ui
with UI_add_user_data().
UI_get0_result()
returns a pointer to the result buffer associated with the information
indexed by i.
UI_process()
goes through the information given so far, does all the printing and
prompting and returns the final status, which is -2 on out-of-band events
(Interrupt, Cancel, ...), -1 on error, or 0 on success.
UI_ctrl()
adds extra control for the application author. For now, it understands two
commands: UI_CTRL_PRINT_ERRORS, which makes
UI_process() print the OpenSSL error stack as part
of processing the ui, and
UI_CTRL_IS_REDOABLE, which returns a flag saying if
the used ui can be used again or not.
UI_set_default_method()
changes the default UI method to the one given. This function is not
thread-safe and should not be called at the same time as other OpenSSL
functions.
UI_get_default_method()
returns a pointer to the current default UI method.
UI_get_method()
returns the UI method associated with a given ui.
UI_set_method()
changes the UI method associated with a given ui.
RETURN VALUES
UI_new() and
UI_new_method() return a valid
UI structure or NULL if an
error occurred.
UI_add_input_string(),
UI_dup_input_string(),
UI_add_verify_string(),
UI_dup_verify_string(),
UI_add_input_boolean(),
UI_dup_input_boolean(),
UI_add_info_string(),
UI_dup_info_string(),
UI_add_error_string(), and
UI_dup_error_string() return a positive number on
success or a number less than or equal to zero otherwise.
UI_construct_prompt() and
UI_get0_result() return a string or
NULL if an error occurred.
UI_add_user_data() and
UI_get0_user_data() return a pointer to the user
data that was contained in ui before the call. In
particular, NULL is a valid return value.
UI_process() returns 0 on success or a
negative value on error.
UI_ctrl() returns a mask on success or -1
on error.
UI_get_default_method() and
UI_OpenSSL() always return a pointer to a valid
UI_METHOD structure.
UI_get_method() and
UI_set_method() return a pointer to the
UI_METHOD structure that is installed in
ui after the call. The OpenSSL documentation says that
they can fail and return NULL, but currently, this
can only happen when and after UI_set_method() is
called with an explicit NULL argument.
SEE ALSO
crypto(3), UI_create_method(3), UI_get_string_type(3), UI_UTIL_read_pw(3)
HISTORY
These functions first appeared in OpenSSL 0.9.7 and have been available since OpenBSD 3.2.
AUTHORS
Richard Levitte <richard@levitte.org> for the OpenSSL project.