Updated: 2022/Sep/29

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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_retry_verify, 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_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>.



3.0.12                            2023-05-07                       SSL_want(3)