#include <openssl/ssl.h> int SSL_do_handshake(SSL *ssl);
If the underlying BIO is blocking, SSL_do_handshake() will only return once the handshake has been finished or an error occurred.
If the underlying BIO is nonblocking, 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 nonblocking 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.
- 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 successfully completed, a TLS/SSL connection has been established.
- 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 if action is needed to continue the operation for nonblocking BIOs. Call SSL_get_error() with the return value ret to find out the reason.
Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at https://www.openssl.org/source/license.html.