BIO_socket_wait, BIO_wait, BIO_do_connect_retry - BIO connection utility functions

       Copyright 2019-2020 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (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>.

3.5.0                                              2025-06-04                              BIO_SOCKET_WAIT(3SSL)

BIO_socket_wait() waits on the socket fd for reading if for_read is not 0, else for writing, at most
       until max_time.  It succeeds immediately if max_time == 0 (which means no timeout given).

       BIO_wait() waits at most until max_time on the given (typically socket-based) bio, for reading if bio is
       supposed to read, else for writing.  It is used by BIO_do_connect_retry() and can be used together
       BIO_read(3).  It succeeds immediately if max_time == 0 (which means no timeout given).  If sockets are
       not available it supports polling by succeeding after sleeping at most the given nap_milliseconds in
       order to avoid a tight busy loop.  Via nap_milliseconds the caller determines the polling granularity.

       BIO_do_connect_retry() connects via the given bio.  It retries BIO_do_connect() as far as needed to reach
       a definite outcome, i.e., connection succeeded, timeout has been reached, or an error occurred.  For
       nonblocking and potentially even non-socket BIOs it polls every nap_milliseconds and sleeps in between
       using BIO_wait().  If nap_milliseconds is < 0 then a default value of 100 ms is used.  If the timeout
       parameter is > 0 this indicates the maximum number of seconds to wait until the connection is established
       or a definite error occurred.  A value of 0 enables waiting indefinitely (i.e, no timeout), while a value
       < 0 means that BIO_do_connect() is tried only once.  The function may, directly or indirectly, invoke
       ERR_clear_error().

BIO_socket_wait(), BIO_wait(), and BIO_do_connect_retry() were added in OpenSSL 3.0.

       BIO_socket_wait, BIO_wait, BIO_do_connect_retry - BIO connection utility functions

BIO_socket_wait(), BIO_wait(), and BIO_do_connect_retry() return -1 on error, 0 on timeout, and 1 on
       success.

BIO_do_connect(3), BIO_read(3)

        #include <openssl/bio.h>

        #ifndef OPENSSL_NO_SOCK
        int BIO_socket_wait(int fd, int for_read, time_t max_time);
        #endif
        int BIO_wait(BIO *bio, time_t max_time, unsigned int nap_milliseconds);
        int BIO_do_connect_retry(BIO *bio, int timeout, int nap_milliseconds);