nect.html">SSL_connect(3)</a> function can return 1, 0 or less than 0. Only a return value of 1 is considered a success. For a simple blocking client we only need to concern ourselves with whether the call was successful or not. Anything else indicates that we have failed to connect to the server.</p>

<p>A common cause of failures at this stage is due to a problem verifying the server&#39;s certificate. For example if the certificate has expired, or it is not signed by a CA in our trusted certificate store