Updated: 2021/Apr/14


SSL_want(3)                         OpenSSL                        SSL_want(3)



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

LIBRARY
       libcrypto, -lcrypto

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_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_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_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 2001-2020 The OpenSSL Project Authors. All Rights Reserved.

       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>.



1.1.1i                            2020-12-10                       SSL_want(3)