NAME

SSL_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:

>0The peek operation was successful; the return value is the number of bytes actually copied from the TLS/SSL connection. 

0The 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 connection 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 initiated by the peer or by something else. 

<0The 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)