SSL_do_handshake(3)

     SSL_do_handshake(3)    0.9.6h (2002-07-19)    SSL_do_handshake(3)

     NAME
          SSL_do_handshake - perform a TLS/SSL handshake

     SYNOPSIS
           #include <openssl/ssl.h>

           int SSL_do_handshake(SSL *ssl);

     DESCRIPTION
          SSL_do_handshake() will wait for a SSL/TLS handshake to take
          place. If the connection is in client mode, the handshake
          will be started. The handshake routines may have to be
          explicitly set in advance using either
          SSL_set_connect_state(3) or SSL_set_accept_state(3).

     NOTES
          The behaviour of SSL_do_handshake() depends on the
          underlying BIO.

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

          If the underlying BIO is non-blocking, SSL_do_handshake()
          will also return when the underlying BIO could not satisfy
          the needs of SSL_do_handshake() to continue the handshake.
          In this case a call to SSL_get_error() with the return value
          of SSL_do_handshake() 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_do_handshake().  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.

          o   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

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     SSL_do_handshake(3)    0.9.6h (2002-07-19)    SSL_do_handshake(3)

              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_accept(3), ssl(3),
          bio(3), SSL_set_connect_state(3)

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