+++ /dev/null
-=pod
-
-=head1 NAME
-
-SSL_extension_supported,
-SSL_CTX_add_client_custom_ext, SSL_CTX_add_server_custom_ext
-- custom TLS extension handling
-
-=head1 SYNOPSIS
-
- #include <openssl/ssl.h>
-
- int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
- custom_ext_add_cb add_cb,
- custom_ext_free_cb free_cb, void *add_arg,
- custom_ext_parse_cb parse_cb,
- void *parse_arg);
-
- int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
- custom_ext_add_cb add_cb,
- custom_ext_free_cb free_cb, void *add_arg,
- custom_ext_parse_cb parse_cb,
- void *parse_arg);
-
- int SSL_extension_supported(unsigned int ext_type);
-
- typedef int (*custom_ext_add_cb)(SSL *s, unsigned int ext_type,
- const unsigned char **out,
- size_t *outlen, int *al,
- void *add_arg);
-
- typedef void (*custom_ext_free_cb)(SSL *s, unsigned int ext_type,
- const unsigned char *out,
- void *add_arg);
-
- typedef int (*custom_ext_parse_cb)(SSL *s, unsigned int ext_type,
- const unsigned char *in,
- size_t inlen, int *al,
- void *parse_arg);
-
-
-=head1 DESCRIPTION
-
-SSL_CTX_add_client_custom_ext() adds a custom extension for a TLS client
-with extension type B<ext_type> and callbacks B<add_cb>, B<free_cb> and
-B<parse_cb>.
-
-SSL_CTX_add_server_custom_ext() adds a custom extension for a TLS server
-with extension type B<ext_type> and callbacks B<add_cb>, B<free_cb> and
-B<parse_cb>.
-
-In both cases the extension type must not be handled by OpenSSL internally
-or an error occurs.
-
-SSL_extension_supported() returns 1 if the extension B<ext_type> is handled
-internally by OpenSSL and 0 otherwise.
-
-=head1 EXTENSION CALLBACKS
-
-The callback B<add_cb> is called to send custom extension data to be
-included in ClientHello for TLS clients or ServerHello for servers. The
-B<ext_type> parameter is set to the extension type which will be added and
-B<add_arg> to the value set when the extension handler was added.
-
-If the application wishes to include the extension B<ext_type> it should
-set B<*out> to the extension data, set B<*outlen> to the length of the
-extension data and return 1.
-
-If the B<add_cb> does not wish to include the extension it must return 0.
-
-If B<add_cb> returns -1 a fatal handshake error occurs using the TLS
-alert value specified in B<*al>.
-
-For clients (but not servers) if B<add_cb> is set to NULL a zero length
-extension is added for B<ext_type>.
-
-For clients every registered B<add_cb> is always called to see if the
-application wishes to add an extension to ClientHello.
-
-For servers every registered B<add_cb> is called once if and only if the
-corresponding extension was received in ClientHello to see if the application
-wishes to add the extension to ServerHello. That is, if no corresponding extension
-was received in ClientHello then B<add_cb> will not be called.
-
-If an extension is added (that is B<add_cb> returns 1) B<free_cb> is called
-(if it is set) with the value of B<out> set by the add callback. It can be
-used to free up any dynamic extension data set by B<add_cb>. Since B<out> is
-constant (to permit use of constant data in B<add_cb>) applications may need to
-cast away const to free the data.
-
-The callback B<parse_cb> receives data for TLS extensions. For TLS clients
-the extension data will come from ServerHello and for TLS servers it will
-come from ClientHello.
-
-The extension data consists of B<inlen> bytes in the buffer B<in> for the
-extension B<extension_type>.
-
-If the B<parse_cb> considers the extension data acceptable it must return
-1. If it returns 0 or a negative value a fatal handshake error occurs
-using the TLS alert value specified in B<*al>.
-
-The buffer B<in> is a temporary internal buffer which will not be valid after
-the callback returns.
-
-=head1 NOTES
-
-The B<add_arg> and B<parse_arg> parameters can be set to arbitrary values
-which will be passed to the corresponding callbacks. They can, for example,
-be used to store the extension data received in a convenient structure or
-pass the extension data to be added or freed when adding extensions.
-
-The B<ext_type> parameter corresponds to the B<extension_type> field of
-RFC5246 et al. It is B<not> a NID.
-
-If the same custom extension type is received multiple times a fatal
-B<decode_error> alert is sent and the handshake aborts. If a custom extension
-is received in ServerHello which was not sent in ClientHello a fatal
-B<unsupported_extension> alert is sent and the handshake is aborted. The
-ServerHello B<add_cb> callback is only called if the corresponding extension
-was received in ClientHello. This is compliant with the TLS specifications.
-This behaviour ensures that each callback is called at most once and that
-an application can never send unsolicited extensions.
-
-=head1 RETURN VALUES
-
-SSL_CTX_add_client_custom_ext() and SSL_CTX_add_server_custom_ext() return 1 for
-success and 0 for failure. A failure can occur if an attempt is made to
-add the same B<ext_type> more than once, if an attempt is made to use an
-extension type handled internally by OpenSSL or if an internal error occurs
-(for example a memory allocation failure).
-
-SSL_extension_supported() returns 1 if the extension B<ext_type> is handled
-internally by OpenSSL and 0 otherwise.
-
-=head1 COPYRIGHT
-
-Copyright 2014-2016 The OpenSSL Project Authors. All Rights Reserved.
-
-Licensed under the OpenSSL license (the "License"). You may not use
-this file except in compliance with the License. You can obtain a copy
-in the file LICENSE in the source distribution or at
-L<https://www.openssl.org/source/license.html>.
-
-=cut
projects / openssl.git / blobdiff