Error handling for OpenSSL

Skilled use of error functions is particularly important for the correct use of open source libraries.

Here is a simple example of an application:

Include header file: Openssl/err.h

Loading error messages
Err_load_err_strings ();
Err_load_crypto_strings ();
Get error number
unsigned long ulerr = Err_get_error ();
Char szerrmsg[1024] = {0};
char *ptmp = NULL;
Format: Error:errid: library: function: Reason
Ptmp = err_error_string (ulerr,szerrmsg);

Other information needs to use the rich functions in the OpenSSL library, and here are 28 functions that you can apply yourself against the instructions.

1) Err_add_error_data

Add descriptive information to the err_data element of this layer error. This function is typically called by individual modules, for example, it can be used to indicate what operation caused the error.

2) Err_clear_error

Clears all error messages. If you do not know all the error messages, there may be other unrelated errors left in the Err_state table.

3) Err_error_string/err_error_string_n

Obtain specific error information based on the error code, including the library where the error occurred, the function that failed, and the cause of the error.

4) Err_free_strings

Releases the error message hash table, usually at the last call.

5) err_func_error_string

Gets the function information of the error based on the fault number.

6) err_get_err_state_table

Gets the hash table that holds the error.

7) Err_get_error

Gets the first error number.

8) Err_get_error_line

Gets the line number of the error, based on the error number.

9) Err_get_error_line_data

Gets an error message based on the error number.

) err_get_implementation

Gets the error handler associated with the hash table operation.

One) err_get_state

Gets the Err_state table.

err_lib_error_string)

Based on the error number, gets the library error.

Err_load_strings)

Loading error messages, called by each module.

Err_load_asn1_strings)

Err_load_bio_strings

Err_load_bn_strings

Err_load_buf_strings

Err_load_comp_strings

Err_load_conf_strings

Err_load_crypto_strings

Err_load_crypto_strings

Err_load_dh_strings

Err_load_dsa_strings

Err_load_dso_strings

Err_load_ec_strings

Err_load_engine_strings

Err_load_err_strings

Err_load_evp_strings

Err_load_obj_strings

Err_load_ocsp_strings

Err_load_pem_strings

Err_load_pkcs12_strings

Err_load_pkcs7_strings

Err_load_rand_strings

Err_load_rsa_strings

Err_load_ui_strings

Err_load_x509_strings

Err_load_x509v3_strings

Each module is implemented to load its own error message.

Err_peek_error)

Gets the first error number.

Err_peek_error_line)

Gets the error line for the first error.

Err_peek_error_line_data)

Gets the number of rows and error messages for the first error.

) Err_peek_last_error

Gets the last error number.

Err_peek_last_error_line)

Gets the line number of the last error.

Err_peek_last_error_line_data)

Gets the line number and error information for the last error.

) err_print_errors

Output the error message to the bio.

ERR_PRINT_ERRORS_CB)

The error message is printed according to the callback function set by the user.

ERR_PRINT_ERRORS_FP)

Prints the error to file.

) Err_put_error

The error message is stored in the error stack specified by top of the Err_state table (the last error).

err_reason_error_string)

Get the cause of the error based on the error number.

Err_remove_state)

Removes thread-related error messages.

Err_set_error_data)

The error message is stored in the error stack specified by top of the Err_state table (the last error).

Err_unload_strings)

Removes the relevant information from the Error hash table.

Error handling for OpenSSL