openssl/ssl/s3_both.c

/* ssl/s3_both.c */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 * 
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 * 
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 * 
 * 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 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 acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from 
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 * 
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS 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 AUTHOR OR 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.
 * 
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */
/* ====================================================================
 * Copyright (c) 1998-2002 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).
 *
 */
/* ====================================================================
 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
 * ECC cipher suite support in OpenSSL originally developed by 
 * SUN MICROSYSTEMS, INC., and contributed to the OpenSSL project.
 */

#include <limits.h>
#include <string.h>
#include <stdio.h>
#include "ssl_locl.h"
#include <openssl/buffer.h>
#include <openssl/rand.h>
#include <openssl/objects.h>
#include <openssl/evp.h>
#include <openssl/x509.h>

/* send s->init_buf in records of type 'type' (SSL3_RT_HANDSHAKE or SSL3_RT_CHANGE_CIPHER_SPEC) */
int ssl3_do_write(SSL *s, int type)
	{
	int ret;

	ret=ssl3_write_bytes(s,type,&s->init_buf->data[s->init_off],
	                     s->init_num);
	if (ret < 0) return(-1);
	if (type == SSL3_RT_HANDSHAKE)
		/* should not be done for 'Hello Request's, but in that case
		 * we'll ignore the result anyway */
		ssl3_finish_mac(s,(unsigned char *)&s->init_buf->data[s->init_off],ret);
	
	if (ret == s->init_num)
		{
		if (s->msg_callback)
			s->msg_callback(1, s->version, type, s->init_buf->data, (size_t)(s->init_off + s->init_num), s, s->msg_callback_arg);
		return(1);
		}
	s->init_off+=ret;
	s->init_num-=ret;
	return(0);
	}

int ssl3_send_finished(SSL *s, int a, int b, const char *sender, int slen)
	{
	unsigned char *p,*d;
	int i;
	unsigned long l;

	if (s->state == a)
		{
		d=(unsigned char *)s->init_buf->data;
		p= &(d[4]);

		i=s->method->ssl3_enc->final_finish_mac(s,
			sender,slen,s->s3->tmp.finish_md);
		s->s3->tmp.finish_md_len = i;
		memcpy(p, s->s3->tmp.finish_md, i);
		p+=i;
		l=i;

                /* Copy the finished so we can use it for
                   renegotiation checks */
                if(s->type == SSL_ST_CONNECT)
                        {
                         OPENSSL_assert(i <= EVP_MAX_MD_SIZE);
                         memcpy(s->s3->previous_client_finished, 
                             s->s3->tmp.finish_md, i);
                         s->s3->previous_client_finished_len=i;
                        }
                else
                        {
                        OPENSSL_assert(i <= EVP_MAX_MD_SIZE);
                        memcpy(s->s3->previous_server_finished, 
                            s->s3->tmp.finish_md, i);
                        s->s3->previous_server_finished_len=i;
                        }

#ifdef OPENSSL_SYS_WIN16
		/* MSVC 1.5 does not clear the top bytes of the word unless
		 * I do this.
		 */
		l&=0xffff;
#endif

		*(d++)=SSL3_MT_FINISHED;
		l2n3(l,d);
		s->init_num=(int)l+4;
		s->init_off=0;

		s->state=b;
		}

	/* SSL3_ST_SEND_xxxxxx_HELLO_B */
	return(ssl3_do_write(s,SSL3_RT_HANDSHAKE));
	}

int ssl3_get_finished(SSL *s, int a, int b)
	{
	int al,i,ok;
	long n;
	unsigned char *p;

	/* the mac has already been generated when we received the
	 * change cipher spec message and is in s->s3->tmp.peer_finish_md
	 */ 

	n=s->method->ssl_get_message(s,
		a,
		b,
		SSL3_MT_FINISHED,
		64, /* should actually be 36+4 :-) */
		&ok);

	if (!ok) return((int)n);

	/* If this occurs, we have missed a message */
	if (!s->s3->change_cipher_spec)
		{
		al=SSL_AD_UNEXPECTED_MESSAGE;
		SSLerr(SSL_F_SSL3_GET_FINISHED,SSL_R_GOT_A_FIN_BEFORE_A_CCS);
		goto f_err;
		}
	s->s3->change_cipher_spec=0;

	p = (unsigned char *)s->init_msg;
	i = s->s3->tmp.peer_finish_md_len;

	if (i != n)
		{
		al=SSL_AD_DECODE_ERROR;
		SSLerr(SSL_F_SSL3_GET_FINISHED,SSL_R_BAD_DIGEST_LENGTH);
		goto f_err;
		}

	if (CRYPTO_memcmp(p, s->s3->tmp.peer_finish_md, i) != 0)
		{
		al=SSL_AD_DECRYPT_ERROR;
		SSLerr(SSL_F_SSL3_GET_FINISHED,SSL_R_DIGEST_CHECK_FAILED);
		goto f_err;
		}

        /* Copy the finished so we can use it for
           renegotiation checks */
        if(s->type == SSL_ST_ACCEPT)
                {
                OPENSSL_assert(i <= EVP_MAX_MD_SIZE);
                memcpy(s->s3->previous_client_finished, 
                    s->s3->tmp.peer_finish_md, i);
                s->s3->previous_client_finished_len=i;
                }
        else
                {
                OPENSSL_assert(i <= EVP_MAX_MD_SIZE);
                memcpy(s->s3->previous_server_finished, 
                    s->s3->tmp.peer_finish_md, i);
                s->s3->previous_server_finished_len=i;
                }

	return(1);
f_err:
	ssl3_send_alert(s,SSL3_AL_FATAL,al);
	return(0);
	}

/* for these 2 messages, we need to
 * ssl->enc_read_ctx			re-init
 * ssl->s3->read_sequence		zero
 * ssl->s3->read_mac_secret		re-init
 * ssl->session->read_sym_enc		assign
 * ssl->session->read_compression	assign
 * ssl->session->read_hash		assign
 */
int ssl3_send_change_cipher_spec(SSL *s, int a, int b)
	{ 
	unsigned char *p;

	if (s->state == a)
		{
		p=(unsigned char *)s->init_buf->data;
		*p=SSL3_MT_CCS;
		s->init_num=1;
		s->init_off=0;

		s->state=b;
		}

	/* SSL3_ST_CW_CHANGE_B */
	return(ssl3_do_write(s,SSL3_RT_CHANGE_CIPHER_SPEC));
	}

static int ssl3_add_cert_to_buf(BUF_MEM *buf, unsigned long *l, X509 *x)
	{
	int n;
	unsigned char *p;

	n=i2d_X509(x,NULL);
	if (!BUF_MEM_grow_clean(buf,(int)(n+(*l)+3)))
		{
		SSLerr(SSL_F_SSL3_ADD_CERT_TO_BUF,ERR_R_BUF_LIB);
		return(-1);
		}
	p=(unsigned char *)&(buf->data[*l]);
	l2n3(n,p);
	i2d_X509(x,&p);
	*l+=n+3;

	return(0);
	}

unsigned long ssl3_output_cert_chain(SSL *s, X509 *x)
	{
	unsigned char *p;
	int i;
	unsigned long l=7;
	BUF_MEM *buf;
	int no_chain;

	if ((s->mode & SSL_MODE_NO_AUTO_CHAIN) || s->ctx->extra_certs)
		no_chain = 1;
	else
		no_chain = 0;

	/* TLSv1 sends a chain with nothing in it, instead of an alert */
	buf=s->init_buf;
	if (!BUF_MEM_grow_clean(buf,10))
		{
		SSLerr(SSL_F_SSL3_OUTPUT_CERT_CHAIN,ERR_R_BUF_LIB);
		return(0);
		}
	if (x != NULL)
		{
		if (no_chain)
			{
			if (ssl3_add_cert_to_buf(buf, &l, x))
				return(0);
			}
		else
			{
			X509_STORE_CTX xs_ctx;

			if (!X509_STORE_CTX_init(&xs_ctx,s->ctx->cert_store,x,NULL))
				{
				SSLerr(SSL_F_SSL3_OUTPUT_CERT_CHAIN,ERR_R_X509_LIB);
				return(0);
				}
			X509_verify_cert(&xs_ctx);
			/* Don't leave errors in the queue */
			ERR_clear_error();
			for (i=0; i < sk_X509_num(xs_ctx.chain); i++)
				{
				x = sk_X509_value(xs_ctx.chain, i);

				if (ssl3_add_cert_to_buf(buf, &l, x))
					{
					X509_STORE_CTX_cleanup(&xs_ctx);
					return 0;
					}
				}
			X509_STORE_CTX_cleanup(&xs_ctx);
			}
		}
	/* Thawte special :-) */
	for (i=0; i<sk_X509_num(s->ctx->extra_certs); i++)
		{
		x=sk_X509_value(s->ctx->extra_certs,i);
		if (ssl3_add_cert_to_buf(buf, &l, x))
			return(0);
		}

	l-=7;
	p=(unsigned char *)&(buf->data[4]);
	l2n3(l,p);
	l+=3;
	p=(unsigned char *)&(buf->data[0]);
	*(p++)=SSL3_MT_CERTIFICATE;
	l2n3(l,p);
	l+=4;
	return(l);
	}

/* Obtain handshake message of message type 'mt' (any if mt == -1),
 * maximum acceptable body length 'max'.
 * The first four bytes (msg_type and length) are read in state 'st1',
 * the body is read in state 'stn'.
 */
long ssl3_get_message(SSL *s, int st1, int stn, int mt, long max, int *ok)
	{
	unsigned char *p;
	unsigned long l;
	long n;
	int i,al;

	if (s->s3->tmp.reuse_message)
		{
		s->s3->tmp.reuse_message=0;
		if ((mt >= 0) && (s->s3->tmp.message_type != mt))
			{
			al=SSL_AD_UNEXPECTED_MESSAGE;
			SSLerr(SSL_F_SSL3_GET_MESSAGE,SSL_R_UNEXPECTED_MESSAGE);
			goto f_err;
			}
		*ok=1;
		s->init_msg = s->init_buf->data + 4;
		s->init_num = (int)s->s3->tmp.message_size;
		return s->init_num;
		}

	p=(unsigned char *)s->init_buf->data;

	if (s->state == st1) /* s->init_num < 4 */
		{
		int skip_message;

		do
			{
			while (s->init_num < 4)
				{
				i=s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,
					&p[s->init_num],4 - s->init_num, 0);
				if (i <= 0)
					{
					s->rwstate=SSL_READING;
					*ok = 0;
					return i;
					}
				s->init_num+=i;
				}
			
			skip_message = 0;
			if (!s->server)
				if (p[0] == SSL3_MT_HELLO_REQUEST)
					/* The server may always send 'Hello Request' messages --
					 * we are doing a handshake anyway now, so ignore them
					 * if their format is correct. Does not count for
					 * 'Finished' MAC. */
					if (p[1] == 0 && p[2] == 0 &&p[3] == 0)
						{
						s->init_num = 0;
						skip_message = 1;

						if (s->msg_callback)
							s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, p, 4, s, s->msg_callback_arg);
						}
			}
		while (skip_message);

		/* s->init_num == 4 */

		if ((mt >= 0) && (*p != mt))
			{
			al=SSL_AD_UNEXPECTED_MESSAGE;
			SSLerr(SSL_F_SSL3_GET_MESSAGE,SSL_R_UNEXPECTED_MESSAGE);
			goto f_err;
			}
		if ((mt < 0) && (*p == SSL3_MT_CLIENT_HELLO) &&
					(st1 == SSL3_ST_SR_CERT_A) &&
					(stn == SSL3_ST_SR_CERT_B))
			{
			/* At this point we have got an MS SGC second client
			 * hello (maybe we should always allow the client to
			 * start a new handshake?). We need to restart the mac.
			 * Don't increment {num,total}_renegotiations because
			 * we have not completed the handshake. */
			ssl3_init_finished_mac(s);
			}

		s->s3->tmp.message_type= *(p++);

		n2l3(p,l);
		if (l > (unsigned long)max)
			{
			al=SSL_AD_ILLEGAL_PARAMETER;
			SSLerr(SSL_F_SSL3_GET_MESSAGE,SSL_R_EXCESSIVE_MESSAGE_SIZE);
			goto f_err;
			}
		if (l > (INT_MAX-4)) /* BUF_MEM_grow takes an 'int' parameter */
			{
			al=SSL_AD_ILLEGAL_PARAMETER;
			SSLerr(SSL_F_SSL3_GET_MESSAGE,SSL_R_EXCESSIVE_MESSAGE_SIZE);
			goto f_err;
			}
		if (l && !BUF_MEM_grow_clean(s->init_buf,(int)l+4))
			{
			SSLerr(SSL_F_SSL3_GET_MESSAGE,ERR_R_BUF_LIB);
			goto err;
			}
		s->s3->tmp.message_size=l;
		s->state=stn;

		s->init_msg = s->init_buf->data + 4;
		s->init_num = 0;
		}

	/* next state (stn) */
	p = s->init_msg;
	n = s->s3->tmp.message_size - s->init_num;
	while (n > 0)
		{
		i=s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,&p[s->init_num],n,0);
		if (i <= 0)
			{
			s->rwstate=SSL_READING;
			*ok = 0;
			return i;
			}
		s->init_num += i;
		n -= i;
		}
	ssl3_finish_mac(s, (unsigned char *)s->init_buf->data, s->init_num + 4);
	if (s->msg_callback)
		s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, s->init_buf->data, (size_t)s->init_num + 4, s, s->msg_callback_arg);
	*ok=1;
	return s->init_num;
f_err:
	ssl3_send_alert(s,SSL3_AL_FATAL,al);
err:
	*ok=0;
	return(-1);
	}

int ssl_cert_type(X509 *x, EVP_PKEY *pkey)
	{
	EVP_PKEY *pk;
	int ret= -1,i;

	if (pkey == NULL)
		pk=X509_get_pubkey(x);
	else
		pk=pkey;
	if (pk == NULL) goto err;

	i=pk->type;
	if (i == EVP_PKEY_RSA)
		{
		ret=SSL_PKEY_RSA_ENC;
		}
	else if (i == EVP_PKEY_DSA)
		{
		ret=SSL_PKEY_DSA_SIGN;
		}
#ifndef OPENSSL_NO_EC
	else if (i == EVP_PKEY_EC)
		{
		ret = SSL_PKEY_ECC;
		}	
#endif
	else if (i == NID_id_GostR3410_94 || i == NID_id_GostR3410_94_cc) 
		{
		ret = SSL_PKEY_GOST94;
		}
	else if (i == NID_id_GostR3410_2001 || i == NID_id_GostR3410_2001_cc) 
		{
		ret = SSL_PKEY_GOST01;
		}
err:
	if(!pkey) EVP_PKEY_free(pk);
	return(ret);
	}

int ssl_verify_alarm_type(long type)
	{
	int al;

	switch(type)
		{
	case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT:
	case X509_V_ERR_UNABLE_TO_GET_CRL:
	case X509_V_ERR_UNABLE_TO_GET_CRL_ISSUER:
		al=SSL_AD_UNKNOWN_CA;
		break;
	case X509_V_ERR_UNABLE_TO_DECRYPT_CERT_SIGNATURE:
	case X509_V_ERR_UNABLE_TO_DECRYPT_CRL_SIGNATURE:
	case X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY:
	case X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD:
	case X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD:
	case X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD:
	case X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD:
	case X509_V_ERR_CERT_NOT_YET_VALID:
	case X509_V_ERR_CRL_NOT_YET_VALID:
	case X509_V_ERR_CERT_UNTRUSTED:
	case X509_V_ERR_CERT_REJECTED:
		al=SSL_AD_BAD_CERTIFICATE;
		break;
	case X509_V_ERR_CERT_SIGNATURE_FAILURE:
	case X509_V_ERR_CRL_SIGNATURE_FAILURE:
		al=SSL_AD_DECRYPT_ERROR;
		break;
	case X509_V_ERR_CERT_HAS_EXPIRED:
	case X509_V_ERR_CRL_HAS_EXPIRED:
		al=SSL_AD_CERTIFICATE_EXPIRED;
		break;
	case X509_V_ERR_CERT_REVOKED:
		al=SSL_AD_CERTIFICATE_REVOKED;
		break;
	case X509_V_ERR_OUT_OF_MEM:
		al=SSL_AD_INTERNAL_ERROR;
		break;
	case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
	case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
	case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
	case X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE:
	case X509_V_ERR_CERT_CHAIN_TOO_LONG:
	case X509_V_ERR_PATH_LENGTH_EXCEEDED:
	case X509_V_ERR_INVALID_CA:
		al=SSL_AD_UNKNOWN_CA;
		break;
	case X509_V_ERR_APPLICATION_VERIFICATION:
		al=SSL_AD_HANDSHAKE_FAILURE;
		break;
	case X509_V_ERR_INVALID_PURPOSE:
		al=SSL_AD_UNSUPPORTED_CERTIFICATE;
		break;
	default:
		al=SSL_AD_CERTIFICATE_UNKNOWN;
		break;
		}
	return(al);
	}

#ifndef OPENSSL_NO_BUF_FREELISTS
/* On some platforms, malloc() performance is bad enough that you can't just
 * free() and malloc() buffers all the time, so we need to use freelists from
 * unused buffers.  Currently, each freelist holds memory chunks of only a
 * given size (list->chunklen); other sized chunks are freed and malloced.
 * This doesn't help much if you're using many different SSL option settings
 * with a given context.  (The options affecting buffer size are
 * max_send_fragment, read buffer vs write buffer,
 * SSL_OP_MICROSOFT_BIG_WRITE_BUFFER, SSL_OP_NO_COMPRESSION, and
 * SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS.)  Using a separate freelist for every
 * possible size is not an option, since max_send_fragment can take on many
 * different values.
 *
 * If you are on a platform with a slow malloc(), and you're using SSL
 * connections with many different settings for these options, and you need to
 * use the SSL_MOD_RELEASE_BUFFERS feature, you have a few options:
 *    - Link against a faster malloc implementation.
 *    - Use a separate SSL_CTX for each option set.
 *    - Improve this code.
 */
static void *
freelist_extract(SSL_CTX *ctx, int for_read, int sz)
	{
	SSL3_BUF_FREELIST *list;
	SSL3_BUF_FREELIST_ENTRY *ent = NULL;
	void *result = NULL;

	CRYPTO_w_lock(CRYPTO_LOCK_SSL_CTX);
	list = for_read ? ctx->rbuf_freelist : ctx->wbuf_freelist;
	if (list != NULL && sz == (int)list->chunklen)
		ent = list->head;
	if (ent != NULL)
		{
		list->head = ent->next;
		result = ent;
		if (--list->len == 0)
			list->chunklen = 0;
		}
	CRYPTO_w_unlock(CRYPTO_LOCK_SSL_CTX);
	if (!result)
		result = OPENSSL_malloc(sz);
	return result;
}

static void
freelist_insert(SSL_CTX *ctx, int for_read, size_t sz, void *mem)
	{
	SSL3_BUF_FREELIST *list;
	SSL3_BUF_FREELIST_ENTRY *ent;

	CRYPTO_w_lock(CRYPTO_LOCK_SSL_CTX);
	list = for_read ? ctx->rbuf_freelist : ctx->wbuf_freelist;
	if (list != NULL &&
	    (sz == list->chunklen || list->chunklen == 0) &&
	    list->len < ctx->freelist_max_len &&
	    sz >= sizeof(*ent))
		{
		list->chunklen = sz;
		ent = mem;
		ent->next = list->head;
		list->head = ent;
		++list->len;
		mem = NULL;
		}

	CRYPTO_w_unlock(CRYPTO_LOCK_SSL_CTX);
	if (mem)
		OPENSSL_free(mem);
	}
#else
#define freelist_extract(c,fr,sz) OPENSSL_malloc(sz)
#define freelist_insert(c,fr,sz,m) OPENSSL_free(m)
#endif

int ssl3_setup_read_buffer(SSL *s)
	{
	unsigned char *p;
	size_t len,align=0,headerlen;
	
	if (SSL_version(s) == DTLS1_VERSION || SSL_version(s) == DTLS1_BAD_VER)
		headerlen = DTLS1_RT_HEADER_LENGTH;
	else
		headerlen = SSL3_RT_HEADER_LENGTH;

#if defined(SSL3_ALIGN_PAYLOAD) && SSL3_ALIGN_PAYLOAD!=0
	align = (-SSL3_RT_HEADER_LENGTH)&(SSL3_ALIGN_PAYLOAD-1);
#endif

	if (s->s3->rbuf.buf == NULL)
		{
		len = SSL3_RT_MAX_PLAIN_LENGTH
			+ SSL3_RT_MAX_ENCRYPTED_OVERHEAD
			+ headerlen + align;
		if (s->options & SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER)
			{
			s->s3->init_extra = 1;
			len += SSL3_RT_MAX_EXTRA;
			}
#ifndef OPENSSL_NO_COMP
		if (!(s->options & SSL_OP_NO_COMPRESSION))
			len += SSL3_RT_MAX_COMPRESSED_OVERHEAD;
#endif
		if ((p=freelist_extract(s->ctx, 1, len)) == NULL)
			goto err;
		s->s3->rbuf.buf = p;
		s->s3->rbuf.len = len;
		}

	s->packet= &(s->s3->rbuf.buf[0]);
	return 1;

err:
	SSLerr(SSL_F_SSL3_SETUP_READ_BUFFER,ERR_R_MALLOC_FAILURE);
	return 0;
	}

int ssl3_setup_write_buffer(SSL *s)
	{
	unsigned char *p;
	size_t len,align=0,headerlen;

	if (SSL_version(s) == DTLS1_VERSION || SSL_version(s) == DTLS1_BAD_VER)
		headerlen = DTLS1_RT_HEADER_LENGTH + 1;
	else
		headerlen = SSL3_RT_HEADER_LENGTH;

#if defined(SSL3_ALIGN_PAYLOAD) && SSL3_ALIGN_PAYLOAD!=0
	align = (-SSL3_RT_HEADER_LENGTH)&(SSL3_ALIGN_PAYLOAD-1);
#endif

	if (s->s3->wbuf.buf == NULL)
		{
		len = s->max_send_fragment
			+ SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD
			+ headerlen + align;
#ifndef OPENSSL_NO_COMP
		if (!(s->options & SSL_OP_NO_COMPRESSION))
			len += SSL3_RT_MAX_COMPRESSED_OVERHEAD;
#endif
		if (!(s->options & SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS))
			len += headerlen + align
				+ SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD;

		if ((p=freelist_extract(s->ctx, 0, len)) == NULL)
			goto err;
		s->s3->wbuf.buf = p;
		s->s3->wbuf.len = len;
		}

	return 1;

err:
	SSLerr(SSL_F_SSL3_SETUP_WRITE_BUFFER,ERR_R_MALLOC_FAILURE);
	return 0;
	}


int ssl3_setup_buffers(SSL *s)
	{
	if (!ssl3_setup_read_buffer(s))
		return 0;
	if (!ssl3_setup_write_buffer(s))
		return 0;
	return 1;
	}

int ssl3_release_write_buffer(SSL *s)
	{
	if (s->s3->wbuf.buf != NULL)
		{
		freelist_insert(s->ctx, 0, s->s3->wbuf.len, s->s3->wbuf.buf);
		s->s3->wbuf.buf = NULL;
		}
	return 1;
	}

int ssl3_release_read_buffer(SSL *s)
	{
	if (s->s3->rbuf.buf != NULL)
		{
		freelist_insert(s->ctx, 1, s->s3->rbuf.len, s->s3->rbuf.buf);
		s->s3->rbuf.buf = NULL;
		}
	return 1;
	}