SSL_METHOD *SSLv23_server_method(void); /* SSLv3 but can rollback to v2 */
SSL_METHOD *SSLv23_client_method(void); /* SSLv3 but can rollback to v2 */
在程序中究竟采用哪一种协议(TLSv1/SSLv2/SSLv3),就看调哪一组构造函数了.
memset (&sa, '\0', sizeof(sa));
sa.sin_family = AF_INET;
sa.sin_addr.s_addr = inet_addr (SERVER_ADDR); /* Server IP */
sa.sin_port = htons (PORT); /* Server Port number */