NAME

       SSL_want, SSL_want_nothing, SSL_want_read, SSL_want_write, SSL_want_x509_lookup,
       SSL_want_retry_verify, SSL_want_async, SSL_want_async_job, SSL_want_client_hello_cb -
       obtain state information TLS/SSL I/O operation

SYNOPSIS

        #include <openssl/ssl.h>

        int SSL_want(const SSL *ssl);
        int SSL_want_nothing(const SSL *ssl);
        int SSL_want_read(const SSL *ssl);
        int SSL_want_write(const SSL *ssl);
        int SSL_want_x509_lookup(const SSL *ssl);
        int SSL_want_retry_verify(const SSL *ssl);
        int SSL_want_async(const SSL *ssl);
        int SSL_want_async_job(const SSL *ssl);
        int SSL_want_client_hello_cb(const SSL *ssl);

DESCRIPTION

       SSL_want() returns state information for the SSL object ssl.

       The other SSL_want_*() calls are shortcuts for the possible states returned by SSL_want().

NOTES

       SSL_want() examines the internal state information of the SSL object. Its return values
       are similar to that of SSL_get_error(3).  Unlike SSL_get_error(3), which also evaluates
       the error queue, the results are obtained by examining an internal state flag only. The
       information must therefore only be used for normal operation under nonblocking I/O. Error
       conditions are not handled and must be treated using SSL_get_error(3).

       The result returned by SSL_want() should always be consistent with the result of
       SSL_get_error(3).

RETURN VALUES

       The following return values can currently occur for SSL_want():

       SSL_NOTHING
           There is no data to be written or to be read.

       SSL_WRITING
           There are data in the SSL buffer that must be written to the underlying BIO layer in
           order to complete the actual SSL_*() operation.  A call to SSL_get_error(3) should
           return SSL_ERROR_WANT_WRITE.

       SSL_READING
           More data must be read from the underlying BIO layer in order to complete the actual
           SSL_*() operation.  A call to SSL_get_error(3) should return SSL_ERROR_WANT_READ.

       SSL_X509_LOOKUP
           The operation did not complete because an application callback set by
           SSL_CTX_set_client_cert_cb() has asked to be called again.  A call to SSL_get_error(3)
           should return SSL_ERROR_WANT_X509_LOOKUP.

       SSL_RETRY_VERIFY
           The operation did not complete because a certificate verification callback has asked
           to be called again via SSL_set_retry_verify(3).  A call to SSL_get_error(3) should
           return SSL_ERROR_WANT_RETRY_VERIFY.

       SSL_ASYNC_PAUSED
           An asynchronous operation partially completed and was then paused. See
           SSL_get_all_async_fds(3). A call to SSL_get_error(3) should return
           SSL_ERROR_WANT_ASYNC.

       SSL_ASYNC_NO_JOBS
           The asynchronous job could not be started because there were no async jobs available
           in the pool (see ASYNC_init_thread(3)). A call to SSL_get_error(3) should return
           SSL_ERROR_WANT_ASYNC_JOB.

       SSL_CLIENT_HELLO_CB
           The operation did not complete because an application callback set by
           SSL_CTX_set_client_hello_cb() has asked to be called again.  A call to
           SSL_get_error(3) should return SSL_ERROR_WANT_CLIENT_HELLO_CB.

       SSL_want_nothing(), SSL_want_read(), SSL_want_write(), SSL_want_x509_lookup(),
       SSL_want_retry_verify(), SSL_want_async(), SSL_want_async_job(), and
       SSL_want_client_hello_cb() return 1 when the corresponding condition is true or 0
       otherwise.

SEE ALSO

       ssl(7), SSL_get_error(3)

HISTORY

       The SSL_want_client_hello_cb() function and the SSL_CLIENT_HELLO_CB return value were
       added in OpenSSL 1.1.1.

COPYRIGHT

       Copyright 2001-2022 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (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>.