2001-08-17 22:32:38 +08:00
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=pod
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=head1 NAME
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2021-01-17 03:43:00 +08:00
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SSL_want, SSL_want_nothing, SSL_want_read, SSL_want_write,
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SSL_want_x509_lookup, SSL_want_retry_verify, SSL_want_async, SSL_want_async_job,
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SSL_want_client_hello_cb - obtain state information TLS/SSL I/O operation
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2001-08-17 22:32:38 +08:00
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=head1 SYNOPSIS
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#include <openssl/ssl.h>
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2005-03-30 19:50:14 +08:00
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int SSL_want(const SSL *ssl);
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int SSL_want_nothing(const SSL *ssl);
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int SSL_want_read(const SSL *ssl);
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int SSL_want_write(const SSL *ssl);
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int SSL_want_x509_lookup(const SSL *ssl);
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2021-01-17 03:43:00 +08:00
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int SSL_want_retry_verify(const SSL *ssl);
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2016-05-04 00:55:00 +08:00
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int SSL_want_async(const SSL *ssl);
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int SSL_want_async_job(const SSL *ssl);
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2017-09-08 06:39:40 +08:00
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int SSL_want_client_hello_cb(const SSL *ssl);
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2001-08-17 22:32:38 +08:00
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=head1 DESCRIPTION
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SSL_want() returns state information for the SSL object B<ssl>.
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The other SSL_want_*() calls are shortcuts for the possible states returned
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by SSL_want().
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=head1 NOTES
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SSL_want() examines the internal state information of the SSL object. Its
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2015-08-18 03:21:33 +08:00
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return values are similar to that of L<SSL_get_error(3)>.
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Unlike L<SSL_get_error(3)>, which also evaluates the
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2001-08-17 22:32:38 +08:00
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error queue, the results are obtained by examining an internal state flag
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only. The information must therefore only be used for normal operation under
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2020-07-17 18:31:26 +08:00
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nonblocking I/O. Error conditions are not handled and must be treated
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2015-08-18 03:21:33 +08:00
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using L<SSL_get_error(3)>.
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2001-08-17 22:32:38 +08:00
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The result returned by SSL_want() should always be consistent with
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2015-08-18 03:21:33 +08:00
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the result of L<SSL_get_error(3)>.
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2001-08-17 22:32:38 +08:00
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=head1 RETURN VALUES
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The following return values can currently occur for SSL_want():
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=over 4
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=item SSL_NOTHING
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There is no data to be written or to be read.
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=item SSL_WRITING
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There are data in the SSL buffer that must be written to the underlying
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B<BIO> layer in order to complete the actual SSL_*() operation.
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2021-01-17 03:43:00 +08:00
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A call to L<SSL_get_error(3)> should return B<SSL_ERROR_WANT_WRITE>.
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2001-08-17 22:32:38 +08:00
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=item SSL_READING
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More data must be read from the underlying B<BIO> layer in order to
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complete the actual SSL_*() operation.
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2021-01-17 03:43:00 +08:00
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A call to L<SSL_get_error(3)> should return B<SSL_ERROR_WANT_READ>.
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2001-08-17 22:32:38 +08:00
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=item SSL_X509_LOOKUP
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The operation did not complete because an application callback set by
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SSL_CTX_set_client_cert_cb() has asked to be called again.
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2021-01-17 03:43:00 +08:00
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A call to L<SSL_get_error(3)> should return B<SSL_ERROR_WANT_X509_LOOKUP>.
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=item SSL_RETRY_VERIFY
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2022-03-07 22:46:58 +08:00
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The operation did not complete because a certificate verification callback
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has asked to be called again via L<SSL_set_retry_verify(3)>.
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2021-01-17 03:43:00 +08:00
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A call to L<SSL_get_error(3)> should return B<SSL_ERROR_WANT_RETRY_VERIFY>.
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2001-08-17 22:32:38 +08:00
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2016-05-04 00:55:00 +08:00
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=item SSL_ASYNC_PAUSED
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An asynchronous operation partially completed and was then paused. See
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L<SSL_get_all_async_fds(3)>. A call to L<SSL_get_error(3)> should return
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2021-01-17 03:43:00 +08:00
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B<SSL_ERROR_WANT_ASYNC>.
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2016-05-04 00:55:00 +08:00
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=item SSL_ASYNC_NO_JOBS
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The asynchronous job could not be started because there were no async jobs
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available in the pool (see ASYNC_init_thread(3)). A call to L<SSL_get_error(3)>
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2021-01-17 03:43:00 +08:00
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should return B<SSL_ERROR_WANT_ASYNC_JOB>.
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2016-05-04 00:55:00 +08:00
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2017-09-08 06:39:40 +08:00
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=item SSL_CLIENT_HELLO_CB
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Add SSL_CTX early callback
Provide a callback interface that gives the application the ability
to adjust the nascent SSL object at the earliest stage of ClientHello
processing, immediately after extensions have been collected but
before they have been processed.
This is akin to BoringSSL's "select_certificate_cb" (though it is not
API compatible), and as the name indicates, one major use is to examine
the supplied server name indication and select what certificate to
present to the client. However, it can also be used to make more
sweeping configuration changes to the SSL object according to the
selected server identity and configuration. That may include adjusting
the permitted TLS versions, swapping out the SSL_CTX object (as is
traditionally done in a tlsext_servername_callback), changing the
server's cipher list, and more.
We also wish to allow an early callback to indicate that it needs to perform
additional work asynchronously and resume processing later. To that effect,
refactor the second half of tls_process_client_hello() into a subroutine to be
called at the post-processing stage (including the early callback itself), to
allow the callback to result in remaining in the same work stage for a later
call to succeed. This requires allocating for and storing the CLIENTHELLO_MSG
in the SSL object to be preserved across such calls, but the storage is
reclaimed after ClientHello processing finishes.
Information about the CliehtHello is available to the callback by means of
accessor functions that can only be used from the early callback. This allows
extensions to make use of the existing internal parsing machinery without
exposing structure internals (e.g., of PACKET), so that applications do not
have to write fragile parsing code.
Applications are encouraged to utilize an early callback and not use
a servername_callback, in order to avoid unexpected behavior that
occurs due to the relative order of processing between things like
session resumption and the historical servername callback.
Also tidy up nearby style by removing unnecessary braces around one-line
conditional bodies.
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2279)
2017-01-24 07:03:16 +08:00
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The operation did not complete because an application callback set by
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2017-09-08 06:39:40 +08:00
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SSL_CTX_set_client_hello_cb() has asked to be called again.
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2021-01-17 03:43:00 +08:00
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A call to L<SSL_get_error(3)> should return B<SSL_ERROR_WANT_CLIENT_HELLO_CB>.
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Add SSL_CTX early callback
Provide a callback interface that gives the application the ability
to adjust the nascent SSL object at the earliest stage of ClientHello
processing, immediately after extensions have been collected but
before they have been processed.
This is akin to BoringSSL's "select_certificate_cb" (though it is not
API compatible), and as the name indicates, one major use is to examine
the supplied server name indication and select what certificate to
present to the client. However, it can also be used to make more
sweeping configuration changes to the SSL object according to the
selected server identity and configuration. That may include adjusting
the permitted TLS versions, swapping out the SSL_CTX object (as is
traditionally done in a tlsext_servername_callback), changing the
server's cipher list, and more.
We also wish to allow an early callback to indicate that it needs to perform
additional work asynchronously and resume processing later. To that effect,
refactor the second half of tls_process_client_hello() into a subroutine to be
called at the post-processing stage (including the early callback itself), to
allow the callback to result in remaining in the same work stage for a later
call to succeed. This requires allocating for and storing the CLIENTHELLO_MSG
in the SSL object to be preserved across such calls, but the storage is
reclaimed after ClientHello processing finishes.
Information about the CliehtHello is available to the callback by means of
accessor functions that can only be used from the early callback. This allows
extensions to make use of the existing internal parsing machinery without
exposing structure internals (e.g., of PACKET), so that applications do not
have to write fragile parsing code.
Applications are encouraged to utilize an early callback and not use
a servername_callback, in order to avoid unexpected behavior that
occurs due to the relative order of processing between things like
session resumption and the historical servername callback.
Also tidy up nearby style by removing unnecessary braces around one-line
conditional bodies.
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2279)
2017-01-24 07:03:16 +08:00
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2001-08-17 22:32:38 +08:00
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=back
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2021-01-17 03:43:00 +08:00
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SSL_want_nothing(), SSL_want_read(), SSL_want_write(),
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SSL_want_x509_lookup(), SSL_want_retry_verify(),
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SSL_want_async(), SSL_want_async_job(), and SSL_want_client_hello_cb()
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return 1 when the corresponding condition is true or 0 otherwise.
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2001-08-17 22:32:38 +08:00
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=head1 SEE ALSO
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2017-03-02 23:07:21 +08:00
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L<ssl(7)>, L<SSL_get_error(3)>
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2001-08-17 22:32:38 +08:00
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Add SSL_CTX early callback
Provide a callback interface that gives the application the ability
to adjust the nascent SSL object at the earliest stage of ClientHello
processing, immediately after extensions have been collected but
before they have been processed.
This is akin to BoringSSL's "select_certificate_cb" (though it is not
API compatible), and as the name indicates, one major use is to examine
the supplied server name indication and select what certificate to
present to the client. However, it can also be used to make more
sweeping configuration changes to the SSL object according to the
selected server identity and configuration. That may include adjusting
the permitted TLS versions, swapping out the SSL_CTX object (as is
traditionally done in a tlsext_servername_callback), changing the
server's cipher list, and more.
We also wish to allow an early callback to indicate that it needs to perform
additional work asynchronously and resume processing later. To that effect,
refactor the second half of tls_process_client_hello() into a subroutine to be
called at the post-processing stage (including the early callback itself), to
allow the callback to result in remaining in the same work stage for a later
call to succeed. This requires allocating for and storing the CLIENTHELLO_MSG
in the SSL object to be preserved across such calls, but the storage is
reclaimed after ClientHello processing finishes.
Information about the CliehtHello is available to the callback by means of
accessor functions that can only be used from the early callback. This allows
extensions to make use of the existing internal parsing machinery without
exposing structure internals (e.g., of PACKET), so that applications do not
have to write fragile parsing code.
Applications are encouraged to utilize an early callback and not use
a servername_callback, in order to avoid unexpected behavior that
occurs due to the relative order of processing between things like
session resumption and the historical servername callback.
Also tidy up nearby style by removing unnecessary braces around one-line
conditional bodies.
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2279)
2017-01-24 07:03:16 +08:00
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=head1 HISTORY
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2018-12-09 08:02:36 +08:00
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The SSL_want_client_hello_cb() function and the SSL_CLIENT_HELLO_CB return value
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were added in OpenSSL 1.1.1.
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Add SSL_CTX early callback
Provide a callback interface that gives the application the ability
to adjust the nascent SSL object at the earliest stage of ClientHello
processing, immediately after extensions have been collected but
before they have been processed.
This is akin to BoringSSL's "select_certificate_cb" (though it is not
API compatible), and as the name indicates, one major use is to examine
the supplied server name indication and select what certificate to
present to the client. However, it can also be used to make more
sweeping configuration changes to the SSL object according to the
selected server identity and configuration. That may include adjusting
the permitted TLS versions, swapping out the SSL_CTX object (as is
traditionally done in a tlsext_servername_callback), changing the
server's cipher list, and more.
We also wish to allow an early callback to indicate that it needs to perform
additional work asynchronously and resume processing later. To that effect,
refactor the second half of tls_process_client_hello() into a subroutine to be
called at the post-processing stage (including the early callback itself), to
allow the callback to result in remaining in the same work stage for a later
call to succeed. This requires allocating for and storing the CLIENTHELLO_MSG
in the SSL object to be preserved across such calls, but the storage is
reclaimed after ClientHello processing finishes.
Information about the CliehtHello is available to the callback by means of
accessor functions that can only be used from the early callback. This allows
extensions to make use of the existing internal parsing machinery without
exposing structure internals (e.g., of PACKET), so that applications do not
have to write fragile parsing code.
Applications are encouraged to utilize an early callback and not use
a servername_callback, in order to avoid unexpected behavior that
occurs due to the relative order of processing between things like
session resumption and the historical servername callback.
Also tidy up nearby style by removing unnecessary braces around one-line
conditional bodies.
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2279)
2017-01-24 07:03:16 +08:00
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2016-05-18 23:44:05 +08:00
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=head1 COPYRIGHT
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2022-05-03 18:52:38 +08:00
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Copyright 2001-2022 The OpenSSL Project Authors. All Rights Reserved.
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2016-05-18 23:44:05 +08:00
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2018-12-06 21:04:44 +08:00
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Licensed under the Apache License 2.0 (the "License"). You may not use
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2016-05-18 23:44:05 +08:00
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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