SSL_ACCEPT(3) OpenSSL SSL_ACCEPT(3)
SSL_accept - wait for a TLS/SSL client to initiate a TLS/SSL
handshake
#include <openssl/ssl.h>
int SSL_accept(SSL *ssl);
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 underly-
ing BIO.
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 cal-
ling 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.
The following return values can occur:
1 The TLS/SSL handshake was successfully completed, a
TLS/SSL connection has been established.
0 The TLS/SSL handshake was not successful but was shut
down controlled and by the specifications of the TLS/SSL
protocol. Call SSL_get_error() with the return value ret
to find out the reason.
<0 The TLS/SSL handshake was not successful because a fatal
error occurred either at the protocol level or a
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SSL_ACCEPT(3) OpenSSL SSL_ACCEPT(3)
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.
SSL_get_error(3), SSL_connect(3), SSL_shutdown(3), ssl(3),
bio(3), SSL_set_connect_state(3), SSL_do_handshake(3),
SSL_CTX_new(3)
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