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a9c0d8beea
"Early callback" is a little ambiguous now that early data exists. Perhaps "ClientHello callback"? Reviewed-by: Rich Salz <rsalz@openssl.org> Reviewed-by: Ben Kaduk <kaduk@mit.edu> (Merged from https://github.com/openssl/openssl/pull/4349)
78 lines
2.8 KiB
Plaintext
78 lines
2.8 KiB
Plaintext
=pod
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=head1 NAME
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SSL_CTX_set_tlsext_servername_callback, SSL_CTX_set_tlsext_servername_arg,
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SSL_get_servername_type, SSL_get_servername,
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SSL_set_tlsext_host_name - handle server name indication (SNI)
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=head1 SYNOPSIS
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#include <openssl/ssl.h>
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long SSL_CTX_set_tlsext_servername_callback(SSL_CTX *ctx,
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int (*cb)(SSL *, int *, void *));
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long SSL_CTX_set_tlsext_servername_arg(SSL_CTX *ctx, void *arg);
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const char *SSL_get_servername(const SSL *s, const int type);
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int SSL_get_servername_type(const SSL *s);
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int SSL_set_tlsext_host_name(const SSL *s, const char *name);
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=head1 DESCRIPTION
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The functionality provided by the servername callback is superseded by the
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ClientHello callback, which can be set using SSL_CTX_set_client_hello_cb().
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The servername callback is retained for historical compatibility.
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SSL_CTX_set_tlsext_servername_callback() sets the application callback B<cb>
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used by a server to perform any actions or configuration required based on
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the servername extension received in the incoming connection. When B<cb>
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is NULL, SNI is not used. The B<arg> value is a pointer which is passed to
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the application callback.
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SSL_CTX_set_tlsext_servername_arg() sets a context-specific argument to be
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passed into the callback for this B<SSL_CTX>.
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SSL_get_servername() returns a servername extension value of the specified
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type if provided in the Client Hello or NULL.
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SSL_get_servername_type() returns the servername type or -1 if no servername
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is present. Currently the only supported type (defined in RFC3546) is
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B<TLSEXT_NAMETYPE_host_name>.
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SSL_set_tlsext_host_name() sets the server name indication ClientHello extension
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to contain the value B<name>. The type of server name indication extension is set
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to B<TLSEXT_NAMETYPE_host_name> (defined in RFC3546).
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=head1 NOTES
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Several callbacks are executed during ClientHello processing, including
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the ClientHello, ALPN, and servername callbacks. The ClientHello callback is
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executed first, then the servername callback, followed by the ALPN callback.
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The SSL_set_tlsext_host_name() function should only be called on SSL objects
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that will act as clients; otherwise the configured B<name> will be ignored.
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=head1 RETURN VALUES
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SSL_CTX_set_tlsext_servername_callback() and
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SSL_CTX_set_tlsext_servername_arg() both always return 1 indicating success.
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SSL_set_tlsext_host_name() returns 1 on success, 0 in case of error.
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=head1 SEE ALSO
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L<ssl(7)>, L<SSL_CTX_set_alpn_select_cb(3)>,
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L<SSL_get0_alpn_selected(3)>, L<SSL_CTX_set_client_hello_cb(3)>
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=head1 COPYRIGHT
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Copyright 2017 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the OpenSSL license (the "License"). You may not use
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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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