SSL_CTX_SET_READ_AHEAD(3)  Library Functions Manual  SSL_CTX_SET_READ_AHEAD(3)

NAME
     SSL_CTX_set_read_ahead, SSL_CTX_get_read_ahead, SSL_set_read_ahead,
     SSL_get_read_ahead, SSL_CTX_get_default_read_ahead - manage whether to
     read as many input bytes as possible

SYNOPSIS
     #include <openssl/ssl.h>

     void
     SSL_CTX_set_read_ahead(SSL_CTX *ctx, int yes);

     long
     SSL_CTX_get_read_ahead(SSL_CTX *ctx);

     void
     SSL_set_read_ahead(SSL *s, int yes);

     long
     SSL_get_read_ahead(const SSL *s);

     long
     SSL_CTX_get_default_read_ahead(SSL_CTX *ctx);

DESCRIPTION
     SSL_CTX_set_read_ahead() and SSL_set_read_ahead() set whether as many
     input bytes as possible are read for non-blocking reads.  For example if
     x bytes are currently required by OpenSSL, but y bytes are available from
     the underlying BIO (where y > x), then OpenSSL will read all y bytes into
     its buffer (provided that the buffer is large enough) if reading ahead is
     on, or x bytes otherwise.  The parameter yes should be 0 to ensure
     reading ahead is off, or non zero otherwise.

     SSL_CTX_get_read_ahead() and SSL_get_read_ahead() indicate whether
     reading ahead is set or not.

     SSL_CTX_get_default_read_ahead() is identical to
     SSL_CTX_get_read_ahead().

     These functions are implemented as macros.

     These functions have no effect when used with DTLS.

RETURN VALUES
     SSL_CTX_get_read_ahead() and SSL_get_read_ahead() return 0 if reading
     ahead is off or non-zero otherwise, except that the return values are
     undefined for DTLS.

SEE ALSO
     ssl(3), SSL_pending(3)

HISTORY
     SSL_set_read_ahead() and SSL_get_read_ahead() appeared in SSLeay 0.4 or
     earlier and have been available since OpenBSD 2.4.

     SSL_CTX_set_read_ahead(), SSL_CTX_get_read_ahead(), and
     SSL_CTX_get_default_read_ahead() first appeared in OpenSSL 0.9.2b and
     have been available since OpenBSD 2.6.

CAVEATS
     Switching read ahead on can impact the behaviour of the SSL_pending(3)
     function.

Linux 6.8.7-arch1-1             March 27, 2018             Linux 6.8.7-arch1-1