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/*
* Copyright (C) 2007-2012 Free Software Foundation, Inc.
*
* Author: Simon Josefsson
*
* This file is part of GnuTLS.
*
* The GnuTLS is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>
*
*/
/* This file contains support functions for 'TLS Handshake Message for
* Supplemental Data' (RFC 4680).
*
* The idea here is simple. gnutls_handshake() in gnuts_handshake.c
* will call _gnutls_gen_supplemental and _gnutls_parse_supplemental
* when some extension requested that supplemental data be sent or
* received. Extension request this by setting the flags
* do_recv_supplemental or do_send_supplemental in the session.
*
* The functions in this file iterate through the _gnutls_supplemental
* array, and calls the send/recv functions for each respective data
* type.
*
* The receive function of each data type is responsible for decoding
* its own data. If the extension did not expect to receive
* supplemental data, it should return GNUTLS_E_UNEXPECTED_PACKET.
* Otherwise, it just parse the data as normal.
*
* The send function needs to append the 2-byte data format type, and
* append the 2-byte length of its data, and the data. If it doesn't
* want to send any data, it is fine to return without doing anything.
*/
#include "gnutls_int.h"
#include "gnutls_supplemental.h"
#include "gnutls_errors.h"
#include "gnutls_num.h"
typedef int (*supp_recv_func) (gnutls_session_t session,
const uint8_t * data, size_t data_size);
typedef int (*supp_send_func) (gnutls_session_t session,
gnutls_buffer_st * buf);
typedef struct
{
const char *name;
gnutls_supplemental_data_format_type_t type;
supp_recv_func supp_recv_func;
supp_send_func supp_send_func;
} gnutls_supplemental_entry;
gnutls_supplemental_entry _gnutls_supplemental[] = {
{0, 0, 0, 0}
};
/**
* gnutls_supplemental_get_name:
* @type: is a supplemental data format type
*
* Convert a #gnutls_supplemental_data_format_type_t value to a
* string.
*
* Returns: a string that contains the name of the specified
* supplemental data format type, or %NULL for unknown types.
**/
const char *
gnutls_supplemental_get_name (gnutls_supplemental_data_format_type_t type)
{
gnutls_supplemental_entry *p;
for (p = _gnutls_supplemental; p->name != NULL; p++)
if (p->type == type)
return p->name;
return NULL;
}
static supp_recv_func
get_supp_func_recv (gnutls_supplemental_data_format_type_t type)
{
gnutls_supplemental_entry *p;
for (p = _gnutls_supplemental; p->name != NULL; p++)
if (p->type == type)
return p->supp_recv_func;
return NULL;
}
int
_gnutls_gen_supplemental (gnutls_session_t session, gnutls_buffer_st * buf)
{
gnutls_supplemental_entry *p;
int ret;
/* Make room for 3 byte length field. */
ret = _gnutls_buffer_append_data (buf, "\0\0\0", 3);
if (ret < 0)
{
gnutls_assert ();
return ret;
}
for (p = _gnutls_supplemental; p->name; p++)
{
supp_send_func supp_send = p->supp_send_func;
size_t sizepos = buf->length;
/* Make room for supplement type and length byte length field. */
ret = _gnutls_buffer_append_data (buf, "\0\0\0\0", 4);
if (ret < 0)
{
gnutls_assert ();
return ret;
}
ret = supp_send (session, buf);
if (ret < 0)
{
gnutls_assert ();
return ret;
}
/* If data were added, store type+length, otherwise reset. */
if (buf->length > sizepos + 4)
{
buf->data[sizepos] = 0;
buf->data[sizepos + 1] = p->type;
buf->data[sizepos + 2] = ((buf->length - sizepos - 4) >> 8) & 0xFF;
buf->data[sizepos + 3] = (buf->length - sizepos - 4) & 0xFF;
}
else
buf->length -= 4;
}
buf->data[0] = ((buf->length - 3) >> 16) & 0xFF;
buf->data[1] = ((buf->length - 3) >> 8) & 0xFF;
buf->data[2] = (buf->length - 3) & 0xFF;
_gnutls_debug_log ("EXT[%p]: Sending %d bytes of supplemental data\n",
session, (int) buf->length);
return buf->length;
}
int
_gnutls_parse_supplemental (gnutls_session_t session,
const uint8_t * data, int datalen)
{
const uint8_t *p = data;
ssize_t dsize = datalen;
size_t total_size;
DECR_LEN (dsize, 3);
total_size = _gnutls_read_uint24 (p);
p += 3;
if (dsize != (ssize_t) total_size)
{
gnutls_assert ();
return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
}
do
{
uint16_t supp_data_type;
uint16_t supp_data_length;
supp_recv_func recv_func;
DECR_LEN (dsize, 2);
supp_data_type = _gnutls_read_uint16 (p);
p += 2;
DECR_LEN (dsize, 2);
supp_data_length = _gnutls_read_uint16 (p);
p += 2;
_gnutls_debug_log ("EXT[%p]: Got supplemental type=%02x length=%d\n",
session, supp_data_type, supp_data_length);
recv_func = get_supp_func_recv (supp_data_type);
if (recv_func)
{
int ret = recv_func (session, p, supp_data_length);
if (ret < 0)
{
gnutls_assert ();
return ret;
}
}
else
{
gnutls_assert ();
return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
}
DECR_LEN (dsize, supp_data_length);
p += supp_data_length;
}
while (dsize > 0);
return 0;
}
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