/* ssl/t1_ext.c */
/* ====================================================================
 * Copyright (c) 2014 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    openssl-core@openssl.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

/* Custom extension utility functions */

#include "ssl_locl.h"

#ifndef OPENSSL_NO_TLSEXT

/* Find a custom extension from the list. */
static custom_ext_method *custom_ext_find(custom_ext_methods *exts,
					  unsigned int ext_type)
	{
	size_t i;
	custom_ext_method *meth = exts->meths;
	for (i = 0; i < exts->meths_count; i++, meth++)
		{
		if (ext_type == meth->ext_type)
			return meth;
		}
	return NULL;
	}
/* Initialise custom extensions flags to indicate neither sent nor
 * received.
 */
void custom_ext_init(custom_ext_methods *exts)
	{
	size_t i;
	custom_ext_method *meth = exts->meths;
	for (i = 0; i < exts->meths_count; i++, meth++)
		meth->ext_flags = 0;
	}

/* Pass received custom extension data to the application for parsing. */
int custom_ext_parse(SSL *s, int server,
		     unsigned int ext_type,
		     const unsigned char *ext_data, 
		     size_t ext_size,
		     int *al)
	{
	custom_ext_methods *exts = server ? &s->cert->srv_ext : &s->cert->cli_ext;
	custom_ext_method *meth;
	meth = custom_ext_find(exts, ext_type);
	/* If not found return success */
	if (!meth)
		return 1;
	if (!server)
		{
		/* If it's ServerHello we can't have any extensions not 
		 * sent in ClientHello.
		 */
		if (!(meth->ext_flags & SSL_EXT_FLAG_SENT))
			{
			*al = TLS1_AD_UNSUPPORTED_EXTENSION;
			return 0;
			}
		}
	/* If already present it's a duplicate */
	if (meth->ext_flags & SSL_EXT_FLAG_RECEIVED)
		{
		*al = TLS1_AD_DECODE_ERROR;
		return 0;
		}
	meth->ext_flags |= SSL_EXT_FLAG_RECEIVED;
	/* If no parse function set return success */
	if (!meth->parse_cb)
		return 1;

	return meth->parse_cb(s, ext_type, ext_data, ext_size, al, meth->parse_arg);
	}

/* Request custom extension data from the application and add to the
 * return buffer.
 */
int custom_ext_add(SSL *s, int server,
		   unsigned char **pret,
		   unsigned char *limit,
		   int *al)
	{
	custom_ext_methods *exts = server ? &s->cert->srv_ext : &s->cert->cli_ext;
	custom_ext_method *meth;
	unsigned char *ret = *pret;
	size_t i;

	for (i = 0; i < exts->meths_count; i++)
		{
		const unsigned char *out = NULL;
		size_t outlen = 0;
		meth = exts->meths + i;

		if (server)
			{
			/* For ServerHello only send extensions present
			 * in ClientHello.
			 */
			if (!(meth->ext_flags & SSL_EXT_FLAG_RECEIVED))
				continue;
			/* If callback absent for server skip it */
			if (!meth->add_cb)
				continue;
			}
		if (meth->add_cb)
			{
			int cb_retval = 0;
			cb_retval = meth->add_cb(s, meth->ext_type,
							&out, &outlen, al,
							meth->add_arg);
			if (cb_retval < 0)
				return 0; /* error */
			if (cb_retval == 0)
					continue; /* skip this extension */
			}
		if (4 > limit - ret || outlen > (size_t)(limit - ret - 4))
			return 0;
		s2n(meth->ext_type, ret);
		s2n(outlen, ret);
		if (outlen)
			{
			memcpy(ret, out, outlen);
			ret += outlen;
			}
		/* We can't send duplicates: code logic should prevent this. */
		OPENSSL_assert(!(meth->ext_flags & SSL_EXT_FLAG_SENT));
		/* Indicate extension has been sent: this is both a sanity
		 * check to ensure we don't send duplicate extensions
		 * and indicates that it is not an error if the extension
		 * is present in ServerHello.
		 */
		meth->ext_flags |= SSL_EXT_FLAG_SENT;
		if (meth->free_cb)
			meth->free_cb(s, meth->ext_type, out, meth->add_arg);
		}
	*pret = ret;
	return 1;
	}

/* Copy table of custom extensions */
int custom_exts_copy(custom_ext_methods *dst, const custom_ext_methods *src)
	{
	if (src->meths_count)
		{
		dst->meths = BUF_memdup(src->meths, sizeof(custom_ext_method) * src->meths_count);
		if (dst->meths == NULL)
			return 0;
		dst->meths_count = src->meths_count;
		}
	return 1;
	}

void custom_exts_free(custom_ext_methods *exts)
	{
	if (exts->meths)
		OPENSSL_free(exts->meths);
	}

/* Set callbacks for a custom extension. */
static int custom_ext_meth_add(custom_ext_methods *exts,
			       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)
	{
	custom_ext_method *meth;
	/* Check application error: if add_cb is not set free_cb will never
	 * be called.
	 */
	if (!add_cb && free_cb)
		return 0;
	/* Don't add if extension supported internally. */
	if (SSL_extension_supported(ext_type))
		return 0;
	/* Extension type must fit in 16 bits */
	if (ext_type > 0xffff)
		return 0;
	/* Search for duplicate */
	if (custom_ext_find(exts, ext_type))
		return 0;
	exts->meths = OPENSSL_realloc(exts->meths,
				      (exts->meths_count + 1) * sizeof(custom_ext_method));

	if (!exts->meths)
		{
		exts->meths_count = 0;
		return 0;
		}

	meth = exts->meths + exts->meths_count;
	memset(meth, 0, sizeof(custom_ext_method));
	meth->parse_cb = parse_cb;
	meth->add_cb = add_cb;
	meth->free_cb = free_cb;
	meth->ext_type = ext_type;
	meth->add_arg = add_arg;
	meth->parse_arg = parse_arg;
	exts->meths_count++;
	return 1;
	}

/* Application level functions to add custom extension callbacks */
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)

	{
	return custom_ext_meth_add(&ctx->cert->cli_ext, ext_type,
				   add_cb, free_cb, add_arg,
				   parse_cb, 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)
	{
	return custom_ext_meth_add(&ctx->cert->srv_ext, ext_type,
				   add_cb, free_cb, add_arg,
				   parse_cb, parse_arg);
	}

int SSL_extension_supported(unsigned int ext_type)
	{
	switch(ext_type)
		{
	/* Internally supported extensions. */
	case TLSEXT_TYPE_application_layer_protocol_negotiation:
	case TLSEXT_TYPE_ec_point_formats:
	case TLSEXT_TYPE_elliptic_curves:
	case TLSEXT_TYPE_heartbeat:
	case TLSEXT_TYPE_next_proto_neg:
	case TLSEXT_TYPE_padding:
	case TLSEXT_TYPE_renegotiate:
	case TLSEXT_TYPE_server_name:
	case TLSEXT_TYPE_session_ticket:
	case TLSEXT_TYPE_signature_algorithms:
	case TLSEXT_TYPE_srp:
	case TLSEXT_TYPE_status_request:
	case TLSEXT_TYPE_use_srtp:
#ifdef TLSEXT_TYPE_opaque_prf_input
	case TLSEXT_TYPE_opaque_prf_input:
#endif
#ifdef TLSEXT_TYPE_encrypt_then_mac
	case TLSEXT_TYPE_encrypt_then_mac:
#endif
		return 1;
	default:
		return 0;
		}
	}
#endif
