trusty (3) SSL_connect.3ssl.gz

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)