LinuxSecurity.com: Marsh Ray and Steve Dispensa discovered a flaw in the TLS and SSLv3protocols. If an attacker could perform a man in the middle attack at thestart of a TLS connection, the attacker could inject arbitrary content atthe beginning of the user's session. This update adds backported supportfor the new RFC5746 renegotiation extension and will use it when both the [More...]
SSL_do_handshake(3openssl) OpenSSL SSL_do_handshake(3openssl)NAME
SSL_do_handshake - perform a TLS/SSL handshake
SYNOPSIS
#include <openssl/ssl.h>
int SSL_do_handshake(SSL *ssl);
DESCRIPTION
SSL_do_handshake() will wait for a SSL/TLS handshake to take place. If the connection is in client mode, the handshake will be started. The
handshake routines may have to be explicitly set in advance using either SSL_set_connect_state(3) or SSL_set_accept_state(3).
NOTES
The behaviour of SSL_do_handshake() depends on the underlying BIO.
If the underlying BIO is blocking, SSL_do_handshake() will only return once the handshake has been finished or an error occurred, except
for SGC (Server Gated Cryptography). For SGC, SSL_do_handshake() may return with -1, but SSL_get_error() will yield
SSL_ERROR_WANT_READ/WRITE and SSL_do_handshake() should be called again.
If the underlying BIO is non-blocking, SSL_do_handshake() will also return when the underlying BIO could not satisfy the needs of
SSL_do_handshake() to continue the handshake. In this case a call to SSL_get_error() with the return value of SSL_do_handshake() will yield
SSL_ERROR_WANT_READ or SSL_ERROR_WANT_WRITE. The calling process then must repeat the call after taking appropriate action to satisfy the
needs of SSL_do_handshake(). The action depends on the underlying BIO. When using a non-blocking socket, nothing is to be done, but
select() can be used to check for the required condition. When using a buffering BIO, like a BIO pair, data must be written into or
retrieved out of the BIO before being able to continue.
RETURN VALUES
The following return values can occur:
1 The TLS/SSL handshake was successfully completed, a TLS/SSL connection has been established.
0 The TLS/SSL handshake was not successful but was shut down controlled and by the specifications of the TLS/SSL protocol. Call
SSL_get_error() with the return value ret to find out the reason.
<0 The TLS/SSL handshake was not successful because a fatal error occurred either at the protocol level or a connection failure occurred.
The shutdown was not clean. It can also occur of action is need to continue the operation for non-blocking BIOs. Call SSL_get_error()
with the return value ret to find out the reason.
SEE ALSO SSL_get_error(3), SSL_connect(3), SSL_accept(3), ssl(3), bio(3), SSL_set_connect_state(3)OpenSSL-0.9.8 Oct 11 2005 SSL_do_handshake(3openssl)