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SSL_WANT(3) Library Functions Manual SSL_WANT(3)

SSL_want, SSL_want_nothing, SSL_want_read, SSL_want_write, SSL_want_x509_lookup —
obtain state information TLS/SSL I/O operation

#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);

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().

SSL_want() examines the internal state information of the SSL object. Its return values are similar to those 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 non-blocking 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).

The following return values can currently occur for SSL_want():
There is no data to be written or to be read.
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.
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.
The operation did not complete because an application callback set by SSL_CTX_set_client_cert_cb(3) has asked to be called again. A call to SSL_get_error(3) should return SSL_ERROR_WANT_X509_LOOKUP.

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

err(3), ssl(3), SSL_get_error(3)

SSL_want(), SSL_want_nothing(), SSL_want_read(), and SSL_want_write() first appeared in SSLeay 0.5.2. SSL_want_x509_lookup() first appeared in SSLeay 0.6.0. These functions have been available since OpenBSD 2.4.
March 27, 2018 OpenBSD-current