1SSL_connect(3) OpenSSL SSL_connect(3)
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6 SSL_connect - initiate the TLS/SSL handshake with an TLS/SSL server
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9 #include <openssl/ssl.h>
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11 int SSL_connect(SSL *ssl);
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14 SSL_connect() initiates the TLS/SSL handshake with a server. The
15 communication channel must already have been set and assigned to the
16 ssl by setting an underlying BIO.
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19 The behaviour of SSL_connect() depends on the underlying BIO.
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21 If the underlying BIO is blocking, SSL_connect() will only return once
22 the handshake has been finished or an error occurred.
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24 If the underlying BIO is non-blocking, SSL_connect() will also return
25 when the underlying BIO could not satisfy the needs of SSL_connect() to
26 continue the handshake, indicating the problem by the return value -1.
27 In this case a call to SSL_get_error() with the return value of
28 SSL_connect() will yield SSL_ERROR_WANT_READ or SSL_ERROR_WANT_WRITE.
29 The calling process then must repeat the call after taking appropriate
30 action to satisfy the needs of SSL_connect(). The action depends on
31 the underlying BIO. When using a non-blocking socket, nothing is to be
32 done, but select() can be used to check for the required condition.
33 When using a buffering BIO, like a BIO pair, data must be written into
34 or retrieved out of the BIO before being able to continue.
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37 The following return values can occur:
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39 0 The TLS/SSL handshake was not successful but was shut down
40 controlled and by the specifications of the TLS/SSL protocol. Call
41 SSL_get_error() with the return value ret to find out the reason.
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43 1 The TLS/SSL handshake was successfully completed, a TLS/SSL
44 connection has been established.
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46 <0 The TLS/SSL handshake was not successful, because a fatal error
47 occurred either at the protocol level or a connection failure
48 occurred. The shutdown was not clean. It can also occur of action
49 is need to continue the operation for non-blocking BIOs. Call
50 SSL_get_error() with the return value ret to find out the reason.
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53 SSL_get_error(3), SSL_accept(3), SSL_shutdown(3), ssl(3), bio(3),
54 SSL_set_connect_state(3), SSL_do_handshake(3), SSL_CTX_new(3)
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581.0.2k 2017-01-26 SSL_connect(3)