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75 lines
2.5 KiB
75 lines
2.5 KiB
=pod |
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=head1 NAME |
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SSL_do_handshake - perform a TLS/SSL handshake |
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=head1 SYNOPSIS |
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#include <openssl/ssl.h> |
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int SSL_do_handshake(SSL *ssl); |
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=head1 DESCRIPTION |
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SSL_do_handshake() will wait for a SSL/TLS handshake to take place. If the |
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connection is in client mode, the handshake will be started. The handshake |
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routines may have to be explicitly set in advance using either |
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L<SSL_set_connect_state(3)|SSL_set_connect_state(3)> or |
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L<SSL_set_accept_state(3)|SSL_set_accept_state(3)>. |
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=head1 NOTES |
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The behaviour of SSL_do_handshake() depends on the underlying BIO. |
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If the underlying BIO is B<blocking>, SSL_do_handshake() will only return |
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once the handshake has been finished or an error occurred, except for SGC |
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(Server Gated Cryptography). For SGC, SSL_do_handshake() may return with -1, |
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but SSL_get_error() will yield B<SSL_ERROR_WANT_READ/WRITE> and |
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SSL_do_handshake() should be called again. |
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If the underlying BIO is B<non-blocking>, SSL_do_handshake() will also return |
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when the underlying BIO could not satisfy the needs of SSL_do_handshake() |
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to continue the handshake. In this case a call to SSL_get_error() with the |
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return value of SSL_do_handshake() will yield B<SSL_ERROR_WANT_READ> or |
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B<SSL_ERROR_WANT_WRITE>. The calling process then must repeat the call after |
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taking appropriate action to satisfy the needs of SSL_do_handshake(). |
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The action depends on the underlying BIO. When using a non-blocking socket, |
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nothing is to be done, but select() can be used to check for the required |
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condition. When using a buffering BIO, like a BIO pair, data must be written |
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into or retrieved out of the BIO before being able to continue. |
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=head1 RETURN VALUES |
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The following return values can occur: |
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=over 4 |
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=item Z<>0 |
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The TLS/SSL handshake was not successful but was shut down controlled and |
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by the specifications of the TLS/SSL protocol. Call SSL_get_error() with the |
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return value B<ret> to find out the reason. |
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=item Z<>1 |
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The TLS/SSL handshake was successfully completed, a TLS/SSL connection has been |
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established. |
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=item E<lt>0 |
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The TLS/SSL handshake was not successful because a fatal error occurred either |
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at the protocol level or a connection failure occurred. The shutdown was |
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not clean. It can also occur of action is need to continue the operation |
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for non-blocking BIOs. Call SSL_get_error() with the return value B<ret> |
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to find out the reason. |
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=back |
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=head1 SEE ALSO |
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L<SSL_get_error(3)|SSL_get_error(3)>, L<SSL_connect(3)|SSL_connect(3)>, |
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L<SSL_accept(3)|SSL_accept(3)>, L<ssl(3)|ssl(3)>, L<bio(3)|bio(3)>, |
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L<SSL_set_connect_state(3)|SSL_set_connect_state(3)> |
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=cut
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