| yuezonghe | 824eb0c | 2024-06-27 02:32:26 -0700 | [diff] [blame] | 1 | =pod |
| 2 | |
| 3 | =head1 NAME |
| 4 | |
| 5 | SSL_accept - wait for a TLS/SSL client to initiate a TLS/SSL handshake |
| 6 | |
| 7 | =head1 SYNOPSIS |
| 8 | |
| 9 | #include <openssl/ssl.h> |
| 10 | |
| 11 | int SSL_accept(SSL *ssl); |
| 12 | |
| 13 | =head1 DESCRIPTION |
| 14 | |
| 15 | SSL_accept() waits for a TLS/SSL client to initiate the TLS/SSL handshake. |
| 16 | The communication channel must already have been set and assigned to the |
| 17 | B<ssl> by setting an underlying B<BIO>. |
| 18 | |
| 19 | =head1 NOTES |
| 20 | |
| 21 | The behaviour of SSL_accept() depends on the underlying BIO. |
| 22 | |
| 23 | If the underlying BIO is B<blocking>, SSL_accept() will only return once the |
| 24 | handshake has been finished or an error occurred. |
| 25 | |
| 26 | If the underlying BIO is B<nonblocking>, SSL_accept() will also return |
| 27 | when the underlying BIO could not satisfy the needs of SSL_accept() |
| 28 | to continue the handshake, indicating the problem by the return value -1. |
| 29 | In this case a call to SSL_get_error() with the |
| 30 | return value of SSL_accept() will yield B<SSL_ERROR_WANT_READ> or |
| 31 | B<SSL_ERROR_WANT_WRITE>. The calling process then must repeat the call after |
| 32 | taking appropriate action to satisfy the needs of SSL_accept(). |
| 33 | The action depends on the underlying BIO. When using a nonblocking socket, |
| 34 | nothing is to be done, but select() can be used to check for the required |
| 35 | condition. When using a buffering BIO, like a BIO pair, data must be written |
| 36 | into or retrieved out of the BIO before being able to continue. |
| 37 | |
| 38 | =head1 RETURN VALUES |
| 39 | |
| 40 | The following return values can occur: |
| 41 | |
| 42 | =over 4 |
| 43 | |
| 44 | =item Z<>0 |
| 45 | |
| 46 | The TLS/SSL handshake was not successful but was shut down controlled and |
| 47 | by the specifications of the TLS/SSL protocol. Call SSL_get_error() with the |
| 48 | return value B<ret> to find out the reason. |
| 49 | |
| 50 | =item Z<>1 |
| 51 | |
| 52 | The TLS/SSL handshake was successfully completed, a TLS/SSL connection has been |
| 53 | established. |
| 54 | |
| 55 | =item E<lt>0 |
| 56 | |
| 57 | The TLS/SSL handshake was not successful because a fatal error occurred either |
| 58 | at the protocol level or a connection failure occurred. The shutdown was |
| 59 | not clean. It can also occur if action is needed to continue the operation |
| 60 | for nonblocking BIOs. Call SSL_get_error() with the return value B<ret> |
| 61 | to find out the reason. |
| 62 | |
| 63 | =back |
| 64 | |
| 65 | =head1 SEE ALSO |
| 66 | |
| 67 | L<SSL_get_error(3)>, L<SSL_connect(3)>, |
| 68 | L<SSL_shutdown(3)>, L<ssl(7)>, L<bio(7)>, |
| 69 | L<SSL_set_connect_state(3)>, |
| 70 | L<SSL_do_handshake(3)>, |
| 71 | L<SSL_CTX_new(3)> |
| 72 | |
| 73 | =head1 COPYRIGHT |
| 74 | |
| 75 | Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved. |
| 76 | |
| 77 | Licensed under the OpenSSL license (the "License"). You may not use |
| 78 | this file except in compliance with the License. You can obtain a copy |
| 79 | in the file LICENSE in the source distribution or at |
| 80 | L<https://www.openssl.org/source/license.html>. |
| 81 | |
| 82 | =cut |