SSL_peek(3)SSL_peek(3)NAMESSL_peek - Copy the data in the SSL buffer into the buffer passed to
this API
SYNOPSIS
#include <openssl/ssl.h>
int SSL_peek(
SSL *s,
void *buf,
int num );
DESCRIPTION
The SSL_peek() function copies num bytes from the specified ssl into
the buffer buf. In constrast to the SSL_read() function, the data in
the SSL buffer is unmodified after the SSL_peek() operation.
RETURN VALUES
The following return values can occur: The peek operation was success‐
ful; the return value is the number of bytes actually copied from the
TLS/SSL connection. The peek operation was not successful; the SSL
connection was closed by the peer by sending a ``close notify'' alert.
The SSL_RECEIVED_SHUTDOWN flag in the ssl shutdown state is set. (See
SSL_shutdown(), SSL_set_shutdown(). Call SSL_get_error() with the
return value ret to determine whether an error occurred or the connec‐
tion was shut down cleanly (SSL_ERROR_ZERO_RETURN).
SSLv2 (deprecated) does not support a shutdown alert protocol,
so it can only be detected, whether the underlying connection
was closed. It cannot be checked, whether the closure was initi‐
ated by the peer or by something else. The peek operation was
not successful, because either an error occurred or action must
be taken by the calling process. Call SSL_get_error() with the
return value ret to find out the reason.
SEE ALSO
Functions: SSL_read(3)SSL_peek(3)
