BIO_SOCKET_WAIT(3ossl)

💖 NAME 💖

Okay bestie, gather ’round: this is the BIO_SOCKET_WAIT(3ossl) manual page, and the stars are BIO_socket_wait, BIO_wait, and BIO_do_connect_retry — literally the BIO connection utility functions. Iconic little trio. 🫶

🛠️ SYNOPSIS 🛠️

#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);

🌸 DESCRIPTION 🌸

• BIO_socket_wait() — It 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() — It 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 with 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() — It 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(). 🔥

🎀 RETURN VALUES 🎀

BIO_socket_wait(), BIO_wait(), and BIO_do_connect_retry() return -1 on error, 0 on timeout, and 1 on success. That’s the whole vibe check. 💅

👑 SEE ALSO 👑

• BIO_do_connect(3)
• BIO_read(3)

🧚 HISTORY 🧚

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

📜 COPYRIGHT 📜

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>.

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That’s the page, bestie 💖 — OpenSSL 3.5.6, dated 2026-04-07, signing off from the 3ossl manual. Slay responsibly. 🧚