NAME¶
SSL_connect - initiate the TLS/SSL handshake with an TLS/SSL server
SYNOPSIS¶
#include <openssl/ssl.h>
int SSL_connect(SSL *ssl);
DESCRIPTION¶
SSL_connect() initiates the TLS/SSL handshake with a server. The
communication channel must already have been set and assigned to the
ssl by setting an underlying
BIO.
NOTES¶
The behaviour of
SSL_connect() depends on the underlying BIO.
If the underlying BIO is
blocking,
SSL_connect() will only return
once the handshake has been finished or an error occurred.
If the underlying BIO is
non-blocking,
SSL_connect() will also
return when the underlying BIO could not satisfy the needs of
SSL_connect() to continue the handshake, indicating the problem by the
return value -1. In this case a call to
SSL_get_error() with the return
value of
SSL_connect() 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_connect().
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:
- 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.
- 1
- The TLS/SSL handshake was successfully completed, a TLS/SSL connection has
been established.
- <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_accept(3),
SSL_shutdown(3),
ssl(3),
bio(3),
SSL_set_connect_state(3),
SSL_do_handshake(3),
SSL_CTX_new(3)