Name

SSL_accept — waits for a TLS/SSL client to initiate the TLS/SSL handshake

Library

libssl.lib

Synopsis

#include <openssl/ssl.h>

int SSL_accept(SSL *ssl);

Detailed Description

SSL_accept() waits for a TLS/SSL client to initiate the TLS/SSL handshake. The communication channel must already have been set and assigned to the ssl by setting an underlying BIO.

Notes

The behaviour of SSL_accept() depends on the underlying BIO.

If the underlying BIO is blocking, SSL_accept() will only return once the handshake has been finished or an error occurred, except for SGC (Server Gated Cryptography). For SGC, SSL_accept() may return with -1, but SSL_get_error() will yield SSL_ERROR_WANT_READ/WRITE and SSL_accept() should be called again.

If the underlying BIO is non-blocking, SSL_accept() will also return when the underlying BIO could not satisfy the needs of SSL_accept() to continue the handshake, indicating the problem by the return value -1. In this case a call to SSL_get_error() with the return value of SSL_accept() will yield SSL_ERROR_WANT_READ or SSL_ERROR_WANT_WRITE. The calling process then must repeat the call after taking appropriate action to satisfy the needs of SSL_accept(). The action depends on the underlying BIO. When using a non-blocking socket, nothing is to be done, but select() can be used to check for the required condition. When using a buffering BIO, like a BIO pair, data must be written into or retrieved out of the BIO before being able to continue.

Return Values

The following return values can occur:

<0

The TLS/SSL handshake was not successful because a fatal error occurred either at the protocol level or a connection failure occurred. The shutdown was not clean. It can also occur of action is need to continue the operation for non-blocking BIOs. Call SSL_get_error() with the return value ret to find out the reason.

See Also

SSL_get_error(), SSL_connect(), SSL_shutdown(), ssl(), bio(), SSL_set_connect_state(), SSL_do_handshake(), SSL_CTX_new()

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