1=pod 2 3=head1 NAME 4 5SSL_write - write bytes to a TLS/SSL connection. 6 7=head1 SYNOPSIS 8 9 #include <openssl/ssl.h> 10
| 1=pod 2 3=head1 NAME 4 5SSL_write - write bytes to a TLS/SSL connection. 6 7=head1 SYNOPSIS 8 9 #include <openssl/ssl.h> 10
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11 int SSL_write(SSL *ssl, char *buf, int num);
| 11 int SSL_write(SSL *ssl, const void *buf, int num);
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12 13=head1 DESCRIPTION 14 15SSL_write() writes B<num> bytes from the buffer B<buf> into the specified 16B<ssl> connection. 17 18=head1 NOTES 19 20If necessary, SSL_write() will negotiate a TLS/SSL session, if
| 12 13=head1 DESCRIPTION 14 15SSL_write() writes B<num> bytes from the buffer B<buf> into the specified 16B<ssl> connection. 17 18=head1 NOTES 19 20If necessary, SSL_write() will negotiate a TLS/SSL session, if
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21not already explicitly performed by SSL_connect() or SSL_accept(). If the
| 21not already explicitly performed by L<SSL_connect(3)|SSL_connect(3)> or 22L<SSL_accept(3)|SSL_accept(3)>. If the
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22peer requests a re-negotiation, it will be performed transparently during 23the SSL_write() operation. The behaviour of SSL_write() depends on the 24underlying BIO. 25
| 23peer requests a re-negotiation, it will be performed transparently during 24the SSL_write() operation. The behaviour of SSL_write() depends on the 25underlying BIO. 26
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| 27For the transparent negotiation to succeed, the B<ssl> must have been 28initialized to client or server mode. This is not the case if a generic 29method is being used (see L<SSL_CTX_new(3)|SSL_CTX_new(3)>, so that 30L<SSL_set_connect_state(3)|SSL_set_connect_state(3)> or SSL_set_accept_state() 31must be used before the first call to an L<SSL_read(3)|SSL_read(3)> 32or SSL_write() function. 33
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26If the underlying BIO is B<blocking>, SSL_write() will only return, once the
| 34If the underlying BIO is B<blocking>, SSL_write() will only return, once the
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27write operation has been finished or an error occurred.
| 35write operation has been finished or an error occurred, except when a 36renegotiation take place, in which case a SSL_ERROR_WANT_READ may occur. 37This behaviour can be controlled with the SSL_MODE_AUTO_RETRY flag of the 38L<SSL_CTX_set_mode(3)|SSL_CTX_set_mode(3)> call.
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28 29If the underlying BIO is B<non-blocking>, SSL_write() will also return, 30when the underlying BIO could not satisfy the needs of SSL_write()
| 39 40If the underlying BIO is B<non-blocking>, SSL_write() will also return, 41when the underlying BIO could not satisfy the needs of SSL_write()
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31to continue the operation. In this case a call to SSL_get_error() with the
| 42to continue the operation. In this case a call to 43L<SSL_get_error(3)|SSL_get_error(3)> with the
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32return value of SSL_write() will yield B<SSL_ERROR_WANT_READ> or 33B<SSL_ERROR_WANT_WRITE>. As at any time a re-negotiation is possible, a 34call to SSL_write() can also cause read operations! The calling process 35then must repeat the call after taking appropriate action to satisfy the 36needs of SSL_write(). The action depends on the underlying BIO. When using a 37non-blocking socket, nothing is to be done, but select() can be used to check 38for the required condition. When using a buffering BIO, like a BIO pair, data 39must be written into or retrieved out of the BIO before being able to continue. 40 41=head1 WARNING 42 43When an SSL_write() operation has to be repeated because of 44B<SSL_ERROR_WANT_READ> or B<SSL_ERROR_WANT_WRITE>, it must be repeated 45with the same arguments. 46 47=head1 RETURN VALUES 48 49The following return values can occur: 50 51=over 4 52 53=item E<gt>0 54 55The write operation was successful, the return value is the number of 56bytes actually written to the TLS/SSL connection. 57 58=item 0 59 60The write operation was not successful. Call SSL_get_error() with the return 61value B<ret> to find out, whether an error occurred. 62 63=item E<lt>0 64 65The write operation was not successful, because either an error occurred 66or action must be taken by the calling process. Call SSL_get_error() with the 67return value B<ret> to find out the reason. 68 69=back 70 71=head1 SEE ALSO 72 73L<SSL_get_error(3)|SSL_get_error(3)>, L<SSL_read(3)|SSL_read(3)>,
| 44return value of SSL_write() will yield B<SSL_ERROR_WANT_READ> or 45B<SSL_ERROR_WANT_WRITE>. As at any time a re-negotiation is possible, a 46call to SSL_write() can also cause read operations! The calling process 47then must repeat the call after taking appropriate action to satisfy the 48needs of SSL_write(). The action depends on the underlying BIO. When using a 49non-blocking socket, nothing is to be done, but select() can be used to check 50for the required condition. When using a buffering BIO, like a BIO pair, data 51must be written into or retrieved out of the BIO before being able to continue. 52 53=head1 WARNING 54 55When an SSL_write() operation has to be repeated because of 56B<SSL_ERROR_WANT_READ> or B<SSL_ERROR_WANT_WRITE>, it must be repeated 57with the same arguments. 58 59=head1 RETURN VALUES 60 61The following return values can occur: 62 63=over 4 64 65=item E<gt>0 66 67The write operation was successful, the return value is the number of 68bytes actually written to the TLS/SSL connection. 69 70=item 0 71 72The write operation was not successful. Call SSL_get_error() with the return 73value B<ret> to find out, whether an error occurred. 74 75=item E<lt>0 76 77The write operation was not successful, because either an error occurred 78or action must be taken by the calling process. Call SSL_get_error() with the 79return value B<ret> to find out the reason. 80 81=back 82 83=head1 SEE ALSO 84 85L<SSL_get_error(3)|SSL_get_error(3)>, L<SSL_read(3)|SSL_read(3)>,
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| 86L<SSL_CTX_set_mode(3)|SSL_CTX_set_mode(3)>, L<SSL_CTX_new(3)|SSL_CTX_new(3)>, 87L<SSL_connect(3)|SSL_connect(3)>, L<SSL_accept(3)|SSL_accept(3)> 88L<SSL_set_connect_state(3)|SSL_set_connect_state(3)>,
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74L<ssl(3)|ssl(3)>, L<bio(3)|bio(3)> 75 76=cut
| 89L<ssl(3)|ssl(3)>, L<bio(3)|bio(3)> 90 91=cut
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