SSL_WANT(3) | Library Functions Manual | SSL_WANT(3)

# NAME

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

# SYNOPSIS

library “libssl” libcrypto
`#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);

# 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`().

`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).

# 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(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.

# SEE ALSO

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

# HISTORY

`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.

June 8, 2025 | Debian