SSL_ALLOC_BUFFERS(3SSL) OpenSSL SSL_ALLOC_BUFFERS(3SSL)
NAME
SSL_free_buffers, SSL_alloc_buffers - manage SSL structure buffers
SYNOPSIS
#include <openssl/ssl.h>
int SSL_free_buffers(SSL *ssl);
int SSL_alloc_buffers(SSL *ssl);
DESCRIPTION
SSL_free_buffers() frees the read and write buffers of the given ssl.
SSL_alloc_buffers() allocates the read and write buffers of the given
ssl.
The SSL_MODE_RELEASE_BUFFERS mode releases read or write buffers
whenever the buffers have been drained. These functions allow
applications to manually control when buffers are freed and allocated.
After freeing the buffers, the buffers are automatically reallocated
upon a new read or write. The SSL_alloc_buffers() does not need to be
called, but can be used to make sure the buffers are preallocated. This
can be used to avoid allocation during data processing or with
CRYPTO_set_mem_functions() to control where and how buffers are
allocated.
These functions are no-ops when used with QUIC SSL objects. For QUIC,
SSL_free_buffers() always fails, and SSL_alloc_buffers() always
succeeds.
RETURN VALUES
The following return values can occur:
0 (Failure)
The SSL_free_buffers() function returns 0 when there is pending data
to be read or written. The SSL_alloc_buffers() function returns 0
when there is an allocation failure.
1 (Success)
The SSL_free_buffers() function returns 1 if the buffers have been
freed. This value is also returned if the buffers had been freed
before calling SSL_free_buffers(). The SSL_alloc_buffers() function
returns 1 if the buffers have been allocated. This value is also
returned if the buffers had been allocated before calling
SSL_alloc_buffers().
SEE ALSO
ssl(7), SSL_free(3), SSL_clear(3), SSL_new(3), SSL_CTX_set_mode(3),
CRYPTO_set_mem_functions(3)
COPYRIGHT
Copyright 2017-2023 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>.
3.5.7 2026-06-09 SSL_ALLOC_BUFFERS(3SSL)
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