There is no point in using BIO_free with a custom recursion
to free up stacked BIOs if there is already BIO_free_all.
Using it consistently avoids memory leaks due to stacked BIOs
not being recursively freed.
freerdp/winpr had the following issues:
* The non reentrant SSL_library_init() was called concurrently (crash)
* Missing code/api to set the eventually required OpenSSL static and dynamic locking callbacks
* Missing code/api to free the application-global or thread-local OpenSSL data and tables
This commit creates two new winpr functions:
BOOL winpr_InitializeSSL(DWORD flags):
Use the flag WINPR_SSL_INIT_ALREADY_INITIALIZED if you want to tell winpr that
your application has already initialized OpenSSL.
If required use the flag WINPR_SSL_INIT_ENABLE_LOCKING to tell winpr that it
should set the OpenSSL static and dynamic locking callbacks.
Otherwise just call it with the flag WINPR_SSL_INIT_DEFAULT.
The recommended way is that your application calls this function once before
any threads are created. However, in order to support lazy OpenSSL library
initialization winpr_InitializeSSL() can also safely be called multiple times
and concurrently because it uses the new InitOnceExecuteOnce() function to
guarantee that the initialization is only performed successfully once during
the life time of the calling process.
BOOL winpr_CleanupSSL(DWORD flags):
If you create a thread that uses SSL you should call this function before the
thread returns using the flag WINPR_SSL_CLEANUP_THREAD in order to clean up
the thread-local OpenSSL data and tables.
Call the function with the flag WINPR_SSL_CLEANUP_GLOBAL before terminating
your application.
Note: This commit only replaced the current occurences of the
SSL_load_error_strings(); SSL_library_init(); pairs in the freerdp source
with winpr_InitializeSSL(). None of the server or client applications has been
changed according to the recommended usage described above (TBDL).
