Becareful when using this function to check errors, as it seems to read from a buffer of errors, which could include errors from another script or process that was using openssl functions. (I was surprised to find it returing error messages before I had called any openssl_* functions)
To clear the errors, you can do:
while ($err = openssl_error_string());
before using openssl functions. I'm not totally sure of the effect this will have on other threads though, maybe someone can clairify.
(PHP 4 >= 4.0.6, PHP 5)
openssl_error_string — Return openSSL error message
openssl_error_string() returns the last error from the openSSL library. Error messages are stacked, so this function should be called multiple times to collect all of the information.
Returns an error message string, or FALSE if there are no more error messages to return.
Example #1 openssl_error_string() example
// lets assume you just called an openssl function that failed
while ($msg = openssl_error_string())
echo $msg . "<br />\n";