=pod

=head1 NAME

BIO_s_socket, BIO_new_socket, BIO_set_send_flags - socket BIO

=head1 SYNOPSIS

 #include <openssl/bio.h>

 const BIO_METHOD *BIO_s_socket(void);

 BIO *BIO_new_socket(int sock, int close_flag);

 long BIO_set_send_flags(BIO *b, int flags);

=head1 DESCRIPTION

BIO_s_socket() returns the socket BIO method. This is a wrapper
round the platform's socket routines.

BIO_read_ex() and BIO_write_ex() read or write the underlying socket.
BIO_puts() is supported but BIO_gets() is not.

If the close flag is set then the socket is shut down and closed
when the BIO is freed.

BIO_new_socket() returns a socket BIO using B<sock> and B<close_flag>.

BIO_set_send_flags() sets flags passed to send(), sendto() and sendmsg().
The set of available flags is platform-dependent. The main intention is to
allow setting the MSG_NOSIGNAL flag to avoid a crash on receiving the SIGPIPE
signal.

=head1 NOTES

Socket BIOs also support any relevant functionality of file descriptor
BIOs.

The reason for having separate file descriptor and socket BIOs is that on some
platforms sockets are not file descriptors and use distinct I/O routines,
Windows is one such platform. Any code mixing the two will not work on
all platforms.

=head1 RETURN VALUES

BIO_s_socket() returns the socket BIO method.

BIO_new_socket() returns the newly allocated BIO or NULL is an error
occurred.

BIO_set_send_flags() returns 1 on success, 0 on errors.

=head1 HISTORY

BIO_set_send_flags() was added in OpenSSL 4.0.

=head1 COPYRIGHT

Copyright 2000-2026 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
L<https://www.openssl.org/source/license.html>.

=cut
