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:
The TLS/SSL handshake was successfully completed, a TLS/SSL
connection has been established.
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.
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.
