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UI_NEW(3)                           OpenSSL                          UI_NEW(3)

NAME

UI, 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_dup_user_data, UI_get0_user_data, UI_get0_result, UI_get_result_length, UI_process, UI_ctrl, UI_set_default_method, UI_get_default_method, UI_get_method, UI_set_method, UI_OpenSSL, UI_null - user interface

SYNOPSIS

#include <openssl/ui.h> typedef struct ui_st UI; 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); 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); int UI_dup_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_get_result_length(UI *ui, int i); int UI_process(UI *ui); int UI_ctrl(UI *ui, int cmd, long i, void *p, void (*f)()); 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); const UI_METHOD *UI_null(void);

DESCRIPTION

UI stands for User Interface, and is 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() or UI_dup_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() and UI_get_result_length() to find the result to the prompt and its length. 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() and UI_get_result_length(). UI_process() can be called more than once on the same UI, thereby allowing a UI to have a long lifetime, but can just as well have a short lifetime. 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_null() returns a UI method that does nothing. Its use is to avoid getting internal defaults for passed UI_METHOD pointers. UI_free() removes a UI from memory, along with all other pieces of memory that's connected to it, like duplicated input strings, results and others. If ui is NULL nothing is done. UI_add_input_string() and UI_add_verify_string() add a prompt to the 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 and 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 the 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 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: an 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 filename "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, it replaces the previous blob with the one given as argument. UI_dup_user_data() duplicates the user data and works as an alternative to UI_add_user_data() when the user data needs to be preserved for a longer duration, perhaps even the lifetime of the application. The UI object takes ownership of this duplicate and will free it whenever it gets replaced or the UI is destroyed. UI_dup_user_data() returns 0 on success, or -1 on memory allocation failure or if the method doesn't have a duplicator function. UI_get0_user_data() retrieves the data that has last been given to the UI with UI_add_user_data() or UI_dup_user_data. UI_get0_result() returns a pointer to the result buffer associated with the information indexed by i. UI_get_result_length() returns the length of 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 and 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.

NOTES

The resulting strings that the built in method UI_OpenSSL() generate are assumed to be encoded according to the current locale or (for Windows) code page. For applications having different demands, these strings need to be converted appropriately by the caller. For Windows, if the OPENSSL_WIN32_UTF8 environment variable is set, the built-in method UI_OpenSSL() will produce UTF-8 encoded strings instead.

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 value which is less than or equal to 0 otherwise. UI_construct_prompt() returns a string or NULL if an error occurred. UI_dup_user_data() returns 0 on success or -1 on error. UI_get0_result() returns a string or NULL on error. UI_get_result_length() returns a positive integer or 0 on success; otherwise it returns -1 on error. 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(), UI_get_method(), UI_OpenSSL(), UI_null() and UI_set_method() return either a valid UI_METHOD structure or NULL respectively.

HISTORY

The UI_dup_user_data() function was added in OpenSSL 1.1.1.

COPYRIGHT

Copyright 2001-2020 The OpenSSL Project Authors. All Rights Reserved. Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>. 1.1.1q 2022-07-05 UI_NEW(3) UI_CREATE_METHOD(3) OpenSSL UI_CREATE_METHOD(3)

NAME

UI_METHOD, UI_create_method, UI_destroy_method, UI_method_set_opener, UI_method_set_writer, UI_method_set_flusher, UI_method_set_reader, UI_method_set_closer, UI_method_set_data_duplicator, UI_method_set_prompt_constructor, UI_method_set_ex_data, UI_method_get_opener, UI_method_get_writer, UI_method_get_flusher, UI_method_get_reader, UI_method_get_closer, UI_method_get_data_duplicator, UI_method_get_data_destructor, UI_method_get_prompt_constructor, UI_method_get_ex_data - user interface method creation and destruction

SYNOPSIS

#include <openssl/ui.h> typedef struct ui_method_st UI_METHOD; UI_METHOD *UI_create_method(const char *name); void UI_destroy_method(UI_METHOD *ui_method); int UI_method_set_opener(UI_METHOD *method, int (*opener) (UI *ui)); int UI_method_set_writer(UI_METHOD *method, int (*writer) (UI *ui, UI_STRING *uis)); int UI_method_set_flusher(UI_METHOD *method, int (*flusher) (UI *ui)); int UI_method_set_reader(UI_METHOD *method, int (*reader) (UI *ui, UI_STRING *uis)); int UI_method_set_closer(UI_METHOD *method, int (*closer) (UI *ui)); int UI_method_set_data_duplicator(UI_METHOD *method, void *(*duplicator) (UI *ui, void *ui_data), void (*destructor)(UI *ui, void *ui_data)); int UI_method_set_prompt_constructor(UI_METHOD *method, char *(*prompt_constructor) (UI *ui, const char *object_desc, const char *object_name)); int UI_method_set_ex_data(UI_METHOD *method, int idx, void *data); int (*UI_method_get_opener(const UI_METHOD *method)) (UI *); int (*UI_method_get_writer(const UI_METHOD *method)) (UI *, UI_STRING *); int (*UI_method_get_flusher(const UI_METHOD *method)) (UI *); int (*UI_method_get_reader(const UI_METHOD *method)) (UI *, UI_STRING *); int (*UI_method_get_closer(const UI_METHOD *method)) (UI *); char *(*UI_method_get_prompt_constructor(const UI_METHOD *method)) (UI *, const char *, const char *); void *(*UI_method_get_data_duplicator(const UI_METHOD *method)) (UI *, void *); void (*UI_method_get_data_destructor(const UI_METHOD *method)) (UI *, void *); const void *UI_method_get_ex_data(const UI_METHOD *method, int idx);

DESCRIPTION

A method contains a few functions that implement the low-level of the User Interface. These functions are: an opener This function takes a reference to a UI and starts a session, for example by opening a channel to a tty, or by creating a dialog box. a writer This function takes a reference to a UI and a UI String, and writes the string where appropriate, maybe to the tty, maybe added as a field label in a dialog box. Note that this gets fed all strings associated with a UI, one after the other, so care must be taken which ones it actually uses. a flusher This function takes a reference to a UI, and flushes everything that has been output so far. For example, if the method builds up a dialog box, this can be used to actually display it and accepting input ended with a pressed button. a reader This function takes a reference to a UI and a UI string and reads off the given prompt, maybe from the tty, maybe from a field in a dialog box. Note that this gets fed all strings associated with a UI, one after the other, so care must be taken which ones it actually uses. a closer This function takes a reference to a UI, and closes the session, maybe by closing the channel to the tty, maybe by destroying a dialog box. All of these functions are expected to return 0 on error, 1 on success, or -1 on out-off-band events, for example if some prompting has been cancelled (by pressing Ctrl-C, for example). Only the flusher or the reader are expected to return -1. If returned by another of the functions, it's treated as if 0 was returned. Regarding the writer and the reader, don't assume the former should only write and don't assume the latter should only read. This depends on the needs of the method. For example, a typical tty reader wouldn't write the prompts in the write, but would rather do so in the reader, because of the sequential nature of prompting on a tty. This is how the UI_OpenSSL() method does it. In contrast, a method that builds up a dialog box would add all prompt text in the writer, have all input read in the flusher and store the results in some temporary buffer, and finally have the reader just fetch those results. The central function that uses these method functions is UI_process(), and it does it in five steps: 1. Open the session using the opener function if that one's defined. If an error occurs, jump to 5. 2. For every UI String associated with the UI, call the writer function if that one's defined. If an error occurs, jump to 5. 3. Flush everything using the flusher function if that one's defined. If an error occurs, jump to 5. 4. For every UI String associated with the UI, call the reader function if that one's defined. If an error occurs, jump to 5. 5. Close the session using the closer function if that one's defined. UI_create_method() creates a new UI method with a given name. UI_destroy_method() destroys the given UI method ui_method. UI_method_set_opener(), UI_method_set_writer(), UI_method_set_flusher(), UI_method_set_reader() and UI_method_set_closer() set the five main method function to the given function pointer. UI_method_set_data_duplicator() sets the user data duplicator and destructor. See UI_dup_user_data(3). UI_method_set_prompt_constructor() sets the prompt constructor. See UI_construct_prompt(3). UI_method_set_ex_data() sets application specific data with a given EX_DATA index. See CRYPTO_get_ex_new_index(3) for general information on how to get that index. UI_method_get_opener(), UI_method_get_writer(), UI_method_get_flusher(), UI_method_get_reader(), UI_method_get_closer(), UI_method_get_data_duplicator(), UI_method_get_data_destructor() and UI_method_get_prompt_constructor() return the different method functions. UI_method_get_ex_data() returns the application data previously stored with UI_method_set_ex_data().

RETURN VALUES

UI_create_method() returns a UI_METHOD pointer on success, NULL on error. UI_method_set_opener(), UI_method_set_writer(), UI_method_set_flusher(), UI_method_set_reader(), UI_method_set_closer(), UI_method_set_data_duplicator() and UI_method_set_prompt_constructor() return 0 on success, -1 if the given method is NULL. UI_method_set_ex_data() returns 1 on success and 0 on error (because CRYPTO_set_ex_data() does so). UI_method_get_opener(), UI_method_get_writer(), UI_method_get_flusher(), UI_method_get_reader(), UI_method_get_closer(), UI_method_get_data_duplicator(), UI_method_get_data_destructor() and UI_method_get_prompt_constructor() return the requested function pointer if it's set in the method, otherwise NULL. UI_method_get_ex_data() returns a pointer to the application specific data associated with the method.

SEE ALSO

UI(3), CRYPTO_get_ex_data(3), UI_STRING(3)

HISTORY

The UI_method_set_data_duplicator(), UI_method_get_data_duplicator() and UI_method_get_data_destructor() functions were added in OpenSSL 1.1.1.

COPYRIGHT

Copyright 2001-2020 The OpenSSL Project Authors. All Rights Reserved. Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>. 1.1.1q 2022-07-05 UI_CREATE_METHOD(3)

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