SSL_accept(3)

     NAME
          SSL_accept - wait for a TLS/SSL client to initiate a TLS/SSL
          handshake

     SYNOPSIS
           #include <openssl/ssl.h>

           int SSL_accept(SSL *ssl);


     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:

          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
              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(3), SSL_connect(3), SSL_shutdown(3), ssl(3),
          bio(3), SSL_set_connect_state(3), SSL_do_handshake(3),
          SSL_CTX_new(3)