s3_pkt.c

/* ssl/s3_pkt.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).
 *
 */

#include <stdio.h>
#include <limits.h>
#include <errno.h>
#define USE_SOCKETS
#include "ssl_locl.h"
#include <openssl/evp.h>
#include <openssl/buffer.h>
#include <openssl/rand.h>

#ifndef  EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK
# define EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK 0
#endif

#if	defined(OPENSSL_SMALL_FOOTPRINT) || \
	!(	defined(AES_ASM) &&	( \
		defined(__x86_64)	|| defined(__x86_64__)	|| \
		defined(_M_AMD64)	|| defined(_M_X64)	|| \
		defined(__INTEL__)	) \
	)
# undef EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK
# define EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK 0
#endif

static int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
			 unsigned int len, int create_empty_fragment);
static int ssl3_get_record(SSL *s);

int ssl3_read_n(SSL *s, int n, int max, int extend)
	{
	/* If extend == 0, obtain new n-byte packet; if extend == 1, increase
	 * packet by another n bytes.
	 * The packet will be in the sub-array of s->s3->rbuf.buf specified
	 * by s->packet and s->packet_length.
	 * (If s->read_ahead is set, 'max' bytes may be stored in rbuf
	 * [plus s->packet_length bytes if extend == 1].)
	 */
	int i,len,left;
	long align=0;
	unsigned char *pkt;
	SSL3_BUFFER *rb;

	if (n <= 0) return n;

	rb    = &(s->s3->rbuf);
	if (rb->buf == NULL)
		if (!ssl3_setup_read_buffer(s))
			return -1;

	left  = rb->left;
#if defined(SSL3_ALIGN_PAYLOAD) && SSL3_ALIGN_PAYLOAD!=0
	align = (long)rb->buf + SSL3_RT_HEADER_LENGTH;
	align = (-align)&(SSL3_ALIGN_PAYLOAD-1);
#endif

	if (!extend)
		{
		/* start with empty packet ... */
		if (left == 0)
			rb->offset = align;
		else if (align != 0 && left >= SSL3_RT_HEADER_LENGTH)
			{
			/* check if next packet length is large
			 * enough to justify payload alignment... */
			pkt = rb->buf + rb->offset;
			if (pkt[0] == SSL3_RT_APPLICATION_DATA
			    && (pkt[3]<<8|pkt[4]) >= 128)
				{
				/* Note that even if packet is corrupted
				 * and its length field is insane, we can
				 * only be led to wrong decision about
				 * whether memmove will occur or not.
				 * Header values has no effect on memmove
				 * arguments and therefore no buffer
				 * overrun can be triggered. */
				memmove (rb->buf+align,pkt,left);
				rb->offset = align;
				}
			}
		s->packet = rb->buf + rb->offset;
		s->packet_length = 0;
		/* ... now we can act as if 'extend' was set */
		}

	/* For DTLS/UDP reads should not span multiple packets
	 * because the read operation returns the whole packet
	 * at once (as long as it fits into the buffer). */
	if (SSL_IS_DTLS(s))
		{
		if (left > 0 && n > left)
			n = left;
		}

	/* if there is enough in the buffer from a previous read, take some */
	if (left >= n)
		{
		s->packet_length+=n;
		rb->left=left-n;
		rb->offset+=n;
		return(n);
		}

	/* else we need to read more data */

	len = s->packet_length;
	pkt = rb->buf+align;
	/* Move any available bytes to front of buffer:
	 * 'len' bytes already pointed to by 'packet',
	 * 'left' extra ones at the end */
	if (s->packet != pkt) /* len > 0 */
		{
		memmove(pkt, s->packet, len+left);
		s->packet = pkt;
		rb->offset = len + align;
		}

	if (n > (int)(rb->len - rb->offset)) /* does not happen */
		{
		SSLerr(SSL_F_SSL3_READ_N,ERR_R_INTERNAL_ERROR);
		return -1;
		}

	if (!s->read_ahead)
		/* ignore max parameter */
		max = n;
	else
		{
		if (max < n)
			max = n;
		if (max > (int)(rb->len - rb->offset))
			max = rb->len - rb->offset;
		}

	while (left < n)
		{
		/* Now we have len+left bytes at the front of s->s3->rbuf.buf
		 * and need to read in more until we have len+n (up to
		 * len+max if possible) */

		clear_sys_error();
		if (s->rbio != NULL)
			{
			s->rwstate=SSL_READING;
			i=BIO_read(s->rbio,pkt+len+left, max-left);
			}
		else
			{
			SSLerr(SSL_F_SSL3_READ_N,SSL_R_READ_BIO_NOT_SET);
			i = -1;
			}

		if (i <= 0)
			{
			rb->left = left;
			if (s->mode & SSL_MODE_RELEASE_BUFFERS &&
				!SSL_IS_DTLS(s))
				if (len+left == 0)
					ssl3_release_read_buffer(s);
			return(i);
			}
		left+=i;
		/* reads should *never* span multiple packets for DTLS because
		 * the underlying transport protocol is message oriented as opposed
		 * to byte oriented as in the TLS case. */
		if (SSL_IS_DTLS(s))
			{
			if (n > left)
				n = left; /* makes the while condition false */
			}
		}

	/* done reading, now the book-keeping */
	rb->offset += n;
	rb->left = left - n;
	s->packet_length += n;
	s->rwstate=SSL_NOTHING;
	return(n);
	}

/* MAX_EMPTY_RECORDS defines the number of consecutive, empty records that will
 * be processed per call to ssl3_get_record. Without this limit an attacker
 * could send empty records at a faster rate than we can process and cause
 * ssl3_get_record to loop forever. */
#define MAX_EMPTY_RECORDS 32

/* Call this to get a new input record.
 * It will return <= 0 if more data is needed, normally due to an error
 * or non-blocking IO.
 * When it finishes, one packet has been decoded and can be found in
 * ssl->s3->rrec.type    - is the type of record
 * ssl->s3->rrec.data, 	 - data
 * ssl->s3->rrec.length, - number of bytes
 */
/* used only by ssl3_read_bytes */
static int ssl3_get_record(SSL *s)
	{
	int ssl_major,ssl_minor,al;
	int enc_err,n,i,ret= -1;
	SSL3_RECORD *rr;
	SSL_SESSION *sess;
	unsigned char *p;
	unsigned char md[EVP_MAX_MD_SIZE];
	short version;
	unsigned mac_size;
	size_t extra;
	unsigned empty_record_count = 0;

	rr= &(s->s3->rrec);
	sess=s->session;

	if (s->options & SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER)
		extra=SSL3_RT_MAX_EXTRA;
	else
		extra=0;
	if (extra && !s->s3->init_extra)
		{
		/* An application error: SLS_OP_MICROSOFT_BIG_SSLV3_BUFFER
		 * set after ssl3_setup_buffers() was done */
		SSLerr(SSL_F_SSL3_GET_RECORD, ERR_R_INTERNAL_ERROR);
		return -1;
		}

again:
	/* check if we have the header */
	if (	(s->rstate != SSL_ST_READ_BODY) ||
		(s->packet_length < SSL3_RT_HEADER_LENGTH)) 
		{
		n=ssl3_read_n(s, SSL3_RT_HEADER_LENGTH, s->s3->rbuf.len, 0);
		if (n <= 0) return(n); /* error or non-blocking */
		s->rstate=SSL_ST_READ_BODY;

		p=s->packet;
		if (s->msg_callback)
			s->msg_callback(0, 0, SSL3_RT_HEADER, p, 5, s, s->msg_callback_arg);

		/* Pull apart the header into the SSL3_RECORD */
		rr->type= *(p++);
		ssl_major= *(p++);
		ssl_minor= *(p++);
		version=(ssl_major<<8)|ssl_minor;
		n2s(p,rr->length);
#if 0
fprintf(stderr, "Record type=%d, Length=%d\n", rr->type, rr->length);
#endif

		/* Lets check version */
		if (!s->first_packet)
			{
			if (version != s->version)
				{
				SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_WRONG_VERSION_NUMBER);
                                if ((s->version & 0xFF00) == (version & 0xFF00) && !s->enc_write_ctx && !s->write_hash)
                                	/* Send back error using their minor version number :-) */
					s->version = (unsigned short)version;
				al=SSL_AD_PROTOCOL_VERSION;
				goto f_err;
				}
			}

		if ((version>>8) != SSL3_VERSION_MAJOR)
			{
			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_WRONG_VERSION_NUMBER);
			goto err;
			}

		if (rr->length > s->s3->rbuf.len - SSL3_RT_HEADER_LENGTH)
			{
			al=SSL_AD_RECORD_OVERFLOW;
			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_PACKET_LENGTH_TOO_LONG);
			goto f_err;
			}

		/* now s->rstate == SSL_ST_READ_BODY */
		}

	/* s->rstate == SSL_ST_READ_BODY, get and decode the data */

	if (rr->length > s->packet_length-SSL3_RT_HEADER_LENGTH)
		{
		/* now s->packet_length == SSL3_RT_HEADER_LENGTH */
		i=rr->length;
		n=ssl3_read_n(s,i,i,1);
		if (n <= 0) return(n); /* error or non-blocking io */
		/* now n == rr->length,
		 * and s->packet_length == SSL3_RT_HEADER_LENGTH + rr->length */
		}

	s->rstate=SSL_ST_READ_HEADER; /* set state for later operations */

	/* At this point, s->packet_length == SSL3_RT_HEADER_LNGTH + rr->length,
	 * and we have that many bytes in s->packet
	 */
	rr->input= &(s->packet[SSL3_RT_HEADER_LENGTH]);

	/* ok, we can now read from 's->packet' data into 'rr'
	 * rr->input points at rr->length bytes, which
	 * need to be copied into rr->data by either
	 * the decryption or by the decompression
	 * When the data is 'copied' into the rr->data buffer,
	 * rr->input will be pointed at the new buffer */ 

	/* We now have - encrypted [ MAC [ compressed [ plain ] ] ]
	 * rr->length bytes of encrypted compressed stuff. */

	/* check is not needed I believe */
	if (rr->length > SSL3_RT_MAX_ENCRYPTED_LENGTH+extra)
		{
		al=SSL_AD_RECORD_OVERFLOW;
		SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_ENCRYPTED_LENGTH_TOO_LONG);
		goto f_err;
		}

	/* decrypt in place in 'rr->input' */
	rr->data=rr->input;
	rr->orig_len=rr->length;
	/* If in encrypt-then-mac mode calculate mac from encrypted record.
	 * All the details below are public so no timing details can leak.
	 */
	if (SSL_USE_ETM(s) && s->read_hash)
		{
		unsigned char *mac;
		mac_size=EVP_MD_CTX_size(s->read_hash);
		OPENSSL_assert(mac_size <= EVP_MAX_MD_SIZE);
		if (rr->length < mac_size)
			{
			al=SSL_AD_DECODE_ERROR;
			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_LENGTH_TOO_SHORT);
			goto f_err;
			}
		rr->length -= mac_size;
		mac = rr->data + rr->length;
		i=s->method->ssl3_enc->mac(s,md,0 /* not send */);
		if (i < 0 || CRYPTO_memcmp(md, mac, (size_t)mac_size) != 0)
			{
			al=SSL_AD_BAD_RECORD_MAC;
			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC);
			goto f_err;
			}
		}

	enc_err = s->method->ssl3_enc->enc(s,0);
	/* enc_err is:
	 *    0: (in non-constant time) if the record is publically invalid.
	 *    1: if the padding is valid
	 *    -1: if the padding is invalid */
	if (enc_err == 0)
		{
		al=SSL_AD_DECRYPTION_FAILED;
		SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_BLOCK_CIPHER_PAD_IS_WRONG);
		goto f_err;
		}

#ifdef TLS_DEBUG
printf("dec %d\n",rr->length);
{ unsigned int z; for (z=0; z<rr->length; z++) printf("%02X%c",rr->data[z],((z+1)%16)?' ':'\n'); }
printf("\n");
#endif

	/* r->length is now the compressed data plus mac */
	if ((sess != NULL) &&
	    (s->enc_read_ctx != NULL) &&
	    (EVP_MD_CTX_md(s->read_hash) != NULL) && !SSL_USE_ETM(s))
		{
		/* s->read_hash != NULL => mac_size != -1 */
		unsigned char *mac = NULL;
		unsigned char mac_tmp[EVP_MAX_MD_SIZE];
		mac_size=EVP_MD_CTX_size(s->read_hash);
		OPENSSL_assert(mac_size <= EVP_MAX_MD_SIZE);

		/* orig_len is the length of the record before any padding was
		 * removed. This is public information, as is the MAC in use,
		 * therefore we can safely process the record in a different
		 * amount of time if it's too short to possibly contain a MAC.
		 */
		if (rr->orig_len < mac_size ||
		    /* CBC records must have a padding length byte too. */
		    (EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE &&
		     rr->orig_len < mac_size+1))
			{
			al=SSL_AD_DECODE_ERROR;
			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_LENGTH_TOO_SHORT);
			goto f_err;
			}

		if (EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE)
			{
			/* We update the length so that the TLS header bytes
			 * can be constructed correctly but we need to extract
			 * the MAC in constant time from within the record,
			 * without leaking the contents of the padding bytes.
			 * */
			mac = mac_tmp;
			ssl3_cbc_copy_mac(mac_tmp, rr, mac_size);
			rr->length -= mac_size;
			}
		else
			{
			/* In this case there's no padding, so |rec->orig_len|
			 * equals |rec->length| and we checked that there's
			 * enough bytes for |mac_size| above. */
			rr->length -= mac_size;
			mac = &rr->data[rr->length];
			}

		i=s->method->ssl3_enc->mac(s,md,0 /* not send */);
		if (i < 0 || mac == NULL || CRYPTO_memcmp(md, mac, (size_t)mac_size) != 0)
			enc_err = -1;
		if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH+extra+mac_size)
			enc_err = -1;
		}

	if (enc_err < 0)
		{
		/* A separate 'decryption_failed' alert was introduced with TLS 1.0,
		 * SSL 3.0 only has 'bad_record_mac'.  But unless a decryption
		 * failure is directly visible from the ciphertext anyway,
		 * we should not reveal which kind of error occurred -- this
		 * might become visible to an attacker (e.g. via a logfile) */
		al=SSL_AD_BAD_RECORD_MAC;
		SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC);
		goto f_err;
		}

	/* r->length is now just compressed */
	if (s->expand != NULL)
		{
		if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH+extra)
			{
			al=SSL_AD_RECORD_OVERFLOW;
			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_COMPRESSED_LENGTH_TOO_LONG);
			goto f_err;
			}
		if (!ssl3_do_uncompress(s))
			{
			al=SSL_AD_DECOMPRESSION_FAILURE;
			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_BAD_DECOMPRESSION);
			goto f_err;
			}
		}

	if (rr->length > SSL3_RT_MAX_PLAIN_LENGTH+extra)
		{
		al=SSL_AD_RECORD_OVERFLOW;
		SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_DATA_LENGTH_TOO_LONG);
		goto f_err;
		}

	rr->off=0;
	/* So at this point the following is true
	 * ssl->s3->rrec.type 	is the type of record
	 * ssl->s3->rrec.length	== number of bytes in record
	 * ssl->s3->rrec.off	== offset to first valid byte
	 * ssl->s3->rrec.data	== where to take bytes from, increment
	 *			   after use :-).
	 */

	/* we have pulled in a full packet so zero things */
	s->packet_length=0;

	/* just read a 0 length packet */
	if (rr->length == 0)
		{
		empty_record_count++;
		if (empty_record_count > MAX_EMPTY_RECORDS)
			{
			al=SSL_AD_UNEXPECTED_MESSAGE;
			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_RECORD_TOO_SMALL);
			goto f_err;
			}
		goto again;
		}

#if 0
fprintf(stderr, "Ultimate Record type=%d, Length=%d\n", rr->type, rr->length);
#endif

	return(1);

f_err:
	ssl3_send_alert(s,SSL3_AL_FATAL,al);
err:
	return(ret);
	}

int ssl3_do_uncompress(SSL *ssl)
	{
#ifndef OPENSSL_NO_COMP
	int i;
	SSL3_RECORD *rr;

	rr= &(ssl->s3->rrec);
	i=COMP_expand_block(ssl->expand,rr->comp,
		SSL3_RT_MAX_PLAIN_LENGTH,rr->data,(int)rr->length);
	if (i < 0)
		return(0);
	else
		rr->length=i;
	rr->data=rr->comp;
#endif
	return(1);
	}

int ssl3_do_compress(SSL *ssl)
	{
#ifndef OPENSSL_NO_COMP
	int i;
	SSL3_RECORD *wr;

	wr= &(ssl->s3->wrec);
	i=COMP_compress_block(ssl->compress,wr->data,
		SSL3_RT_MAX_COMPRESSED_LENGTH,
		wr->input,(int)wr->length);
	if (i < 0)
		return(0);
	else
		wr->length=i;

	wr->input=wr->data;
#endif
	return(1);
	}

/* Call this to write data in records of type 'type'
 * It will return <= 0 if not all data has been sent or non-blocking IO.
 */
int ssl3_write_bytes(SSL *s, int type, const void *buf_, int len)
	{
	const unsigned char *buf=buf_;
	int tot;
	unsigned int n,nw;
#if !defined(OPENSSL_NO_MULTIBLOCK) && EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK
	unsigned int max_send_fragment;
#endif
	SSL3_BUFFER *wb=&(s->s3->wbuf);
	int i;
	unsigned int u_len = (unsigned int)len;

	if (len < 0)
		{
		SSLerr(SSL_F_SSL3_WRITE_BYTES,SSL_R_SSL_NEGATIVE_LENGTH);
		return -1;
		}

	s->rwstate=SSL_NOTHING;
	OPENSSL_assert(s->s3->wnum <= INT_MAX);
	tot=s->s3->wnum;
	s->s3->wnum=0;

	if (SSL_in_init(s) && !s->in_handshake)
		{
		i=s->handshake_func(s);
		if (i < 0) return(i);
		if (i == 0)
			{
			SSLerr(SSL_F_SSL3_WRITE_BYTES,SSL_R_SSL_HANDSHAKE_FAILURE);
			return -1;
			}
		}

	/* ensure that if we end up with a smaller value of data to write 
	 * out than the the original len from a write which didn't complete 
	 * for non-blocking I/O and also somehow ended up avoiding 
	 * the check for this in ssl3_write_pending/SSL_R_BAD_WRITE_RETRY as
	 * it must never be possible to end up with (len-tot) as a large
	 * number that will then promptly send beyond the end of the users
	 * buffer ... so we trap and report the error in a way the user
	 * will notice
	 */
	if (len < tot)
		{
		SSLerr(SSL_F_SSL3_WRITE_BYTES,SSL_R_BAD_LENGTH);
		return(-1);
		}

	/* first check if there is a SSL3_BUFFER still being written
	 * out.  This will happen with non blocking IO */
	if (wb->left != 0)
		{
		i = ssl3_write_pending(s,type,&buf[tot],s->s3->wpend_tot);
		if (i<=0)
			{
			/* XXX should we ssl3_release_write_buffer if i<0? */
			s->s3->wnum=tot;
			return i;
			}
		tot += i;	/* this might be last fragment */
		}

#if !defined(OPENSSL_NO_MULTIBLOCK) && EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK
	/*
	 * Depending on platform multi-block can deliver several *times*
	 * better performance. Downside is that it has to allocate
	 * jumbo buffer to accomodate up to 8 records, but the
	 * compromise is considered worthy.
	 */
	if (type==SSL3_RT_APPLICATION_DATA &&
	    u_len >= 4*(max_send_fragment=s->max_send_fragment) &&
	    s->compress==NULL && s->msg_callback==NULL &&
	    !SSL_USE_ETM(s) && SSL_USE_EXPLICIT_IV(s) &&
	    EVP_CIPHER_flags(s->enc_write_ctx->cipher)&EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK)
		{
		unsigned char aad[13];
		EVP_CTRL_TLS1_1_MULTIBLOCK_PARAM mb_param;
		int packlen;

		/* minimize address aliasing conflicts */
		if ((max_send_fragment&0xfff) == 0)
			max_send_fragment -= 512;

		if (tot==0 || wb->buf==NULL)	/* allocate jumbo buffer */
			{
			ssl3_release_write_buffer(s);

			packlen = EVP_CIPHER_CTX_ctrl(s->enc_write_ctx,
					EVP_CTRL_TLS1_1_MULTIBLOCK_MAX_BUFSIZE,
					max_send_fragment,NULL);

			if (u_len >= 8*max_send_fragment)	packlen *= 8;
			else				packlen *= 4;

			wb->buf=OPENSSL_malloc(packlen);
			wb->len=packlen;
			}
		else if (tot==len)		/* done? */
			{
			OPENSSL_free(wb->buf);	/* free jumbo buffer */
			wb->buf = NULL;
			return tot;
			}

		n=(len-tot);
		for (;;)
			{
			if (n < 4*max_send_fragment)
				{
				OPENSSL_free(wb->buf);	/* free jumbo buffer */
				wb->buf = NULL;
				break;
				}

			if (s->s3->alert_dispatch)
				{
				i=s->method->ssl_dispatch_alert(s);
				if (i <= 0)
					{
					s->s3->wnum=tot;
					return i;
					}
				}

			if (n >= 8*max_send_fragment)
				nw = max_send_fragment*(mb_param.interleave=8);
			else
				nw = max_send_fragment*(mb_param.interleave=4);

			memcpy(aad,s->s3->write_sequence,8);
			aad[8]=type;
			aad[9]=(unsigned char)(s->version>>8);
			aad[10]=(unsigned char)(s->version);
			aad[11]=0;
			aad[12]=0;
			mb_param.out = NULL;
			mb_param.inp = aad;
			mb_param.len = nw;

			packlen = EVP_CIPHER_CTX_ctrl(s->enc_write_ctx,
					EVP_CTRL_TLS1_1_MULTIBLOCK_AAD,
					sizeof(mb_param),&mb_param);

			if (packlen<=0 || packlen>(int)wb->len)	/* never happens */
				{
				OPENSSL_free(wb->buf);	/* free jumbo buffer */
				wb->buf = NULL;
				break;
				}

			mb_param.out = wb->buf;
			mb_param.inp = &buf[tot];
			mb_param.len = nw;

			if (EVP_CIPHER_CTX_ctrl(s->enc_write_ctx,
					EVP_CTRL_TLS1_1_MULTIBLOCK_ENCRYPT,
					sizeof(mb_param),&mb_param)<=0)
				return -1;

			s->s3->write_sequence[7] += mb_param.interleave;
			if (s->s3->write_sequence[7] < mb_param.interleave)
				{
				int j=6;
				while (j>=0 && (++s->s3->write_sequence[j--])==0) ;
				}

			wb->offset = 0;
			wb->left = packlen;

			s->s3->wpend_tot = nw;
			s->s3->wpend_buf = &buf[tot];
			s->s3->wpend_type= type;
			s->s3->wpend_ret = nw;

			i = ssl3_write_pending(s,type,&buf[tot],nw);
			if (i<=0)
				{
				if (i<0)
					{
					OPENSSL_free(wb->buf);
					wb->buf = NULL;
					}
				s->s3->wnum=tot;
				return i;
				}
			if (i==(int)n)
				{
				OPENSSL_free(wb->buf);	/* free jumbo buffer */
				wb->buf = NULL;
				return tot+i;
				}
			n-=i;
			tot+=i;
			}
		}
	else
#endif
	if (tot==len)		/* done? */
		{
		if (s->mode & SSL_MODE_RELEASE_BUFFERS &&
			!SSL_IS_DTLS(s))
			ssl3_release_write_buffer(s);

		return tot;
		}


	n=(len-tot);
	for (;;)
		{
		if (n > s->max_send_fragment)
			nw=s->max_send_fragment;
		else
			nw=n;

		i=do_ssl3_write(s, type, &(buf[tot]), nw, 0);
		if (i <= 0)
			{
			/* XXX should we ssl3_release_write_buffer if i<0? */
			s->s3->wnum=tot;
			return i;
			}

		if ((i == (int)n) ||
			(type == SSL3_RT_APPLICATION_DATA &&
			 (s->mode & SSL_MODE_ENABLE_PARTIAL_WRITE)))
			{
			/* next chunk of data should get another prepended empty fragment
			 * in ciphersuites with known-IV weakness: */
			s->s3->empty_fragment_done = 0;

			if ((i==(int)n) && s->mode & SSL_MODE_RELEASE_BUFFERS &&
				!SSL_IS_DTLS(s))
				ssl3_release_write_buffer(s);

			return tot+i;
			}

		n-=i;
		tot+=i;
		}
	}

static int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
			 unsigned int len, int create_empty_fragment)
	{
	unsigned char *p,*plen;
	int i,mac_size,clear=0;
	int prefix_len=0;
	int eivlen;
	long align=0;
	SSL3_RECORD *wr;
	SSL3_BUFFER *wb=&(s->s3->wbuf);
	SSL_SESSION *sess;


	/* first check if there is a SSL3_BUFFER still being written
	 * out.  This will happen with non blocking IO */
	if (wb->left != 0)
		return(ssl3_write_pending(s,type,buf,len));

	/* If we have an alert to send, lets send it */
	if (s->s3->alert_dispatch)
		{
		i=s->method->ssl_dispatch_alert(s);
		if (i <= 0)
			return(i);
		/* if it went, fall through and send more stuff */
		}

 	if (wb->buf == NULL)
		if (!ssl3_setup_write_buffer(s))
			return -1;

	if (len == 0 && !create_empty_fragment)
		return 0;

	wr= &(s->s3->wrec);
	sess=s->session;

	if (	(sess == NULL) ||
		(s->enc_write_ctx == NULL) ||
		(EVP_MD_CTX_md(s->write_hash) == NULL))
		{
#if 1
		clear=s->enc_write_ctx?0:1;	/* must be AEAD cipher */
#else
		clear=1;
#endif
		mac_size=0;
		}
	else
		{
		mac_size=EVP_MD_CTX_size(s->write_hash);
		if (mac_size < 0)
			goto err;
		}

#if 0 && !defined(OPENSSL_NO_MULTIBLOCK) && EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK
	if (type==SSL3_RT_APPLICATION_DATA && s->compress==NULL &&
	    !SSL_USE_ETM(s) && SSL_USE_EXPLICIT_IV(s) && /*!SSL_IS_DTLS(s) &&*/
	    EVP_CIPHER_flags(s->enc_write_ctx->cipher)&EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK)
		do {
		unsigned char aad[13];
		EVP_CTRL_TLS1_1_MULTIBLOCK_PARAM mb_param = {NULL,aad,sizeof(aad),0};
		int packlen;

		memcpy(aad,s->s3->write_sequence,8);
		aad[8]=type;
		aad[9]=(unsigned char)(s->version>>8);
		aad[10]=(unsigned char)(s->version);
		aad[11]=(unsigned char)(len>>8);
		aad[12]=(unsigned char)len;
		packlen = EVP_CIPHER_CTX_ctrl(s->enc_write_ctx,
				EVP_CTRL_TLS1_1_MULTIBLOCK_AAD,
				sizeof(mb_param),&mb_param);

		if (packlen==0 || packlen > wb->len) break;

		mb_param.out = wb->buf;
		mb_param.inp = buf;
		mb_param.len = len;
		EVP_CIPHER_CTX_ctrl(s->enc_write_ctx,
				EVP_CTRL_TLS1_1_MULTIBLOCK_ENCRYPT,
				sizeof(mb_param),&mb_param);

		s->s3->write_sequence[7] += mb_param.interleave;
		if (s->s3->write_sequence[7] < mb_param.interleave)
			{
			int j=6;
			while (j>=0 && (++s->s3->write_sequence[j--])==0) ;
			}

		wb->offset=0;
		wb->left = packlen;

		/* memorize arguments so that ssl3_write_pending can detect bad write retries later */
		s->s3->wpend_tot=len;
		s->s3->wpend_buf=buf;
		s->s3->wpend_type=type;
		s->s3->wpend_ret=len;

		/* we now just need to write the buffer */
		return ssl3_write_pending(s,type,buf,len);
		} while (0);
#endif

	/* 'create_empty_fragment' is true only when this function calls itself */
	if (!clear && !create_empty_fragment && !s->s3->empty_fragment_done)
		{
		/* countermeasure against known-IV weakness in CBC ciphersuites
		 * (see http://www.openssl.org/~bodo/tls-cbc.txt) */

		if (s->s3->need_empty_fragments && type == SSL3_RT_APPLICATION_DATA)
			{
			/* recursive function call with 'create_empty_fragment' set;
			 * this prepares and buffers the data for an empty fragment
			 * (these 'prefix_len' bytes are sent out later
			 * together with the actual payload) */
			prefix_len = do_ssl3_write(s, type, buf, 0, 1);
			if (prefix_len <= 0)
				goto err;

			if (prefix_len >
		(SSL3_RT_HEADER_LENGTH + SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD))
				{
				/* insufficient space */
				SSLerr(SSL_F_DO_SSL3_WRITE, ERR_R_INTERNAL_ERROR);
				goto err;
				}
			}
		
		s->s3->empty_fragment_done = 1;
		}

	if (create_empty_fragment)
		{
#if defined(SSL3_ALIGN_PAYLOAD) && SSL3_ALIGN_PAYLOAD!=0
		/* extra fragment would be couple of cipher blocks,
		 * which would be multiple of SSL3_ALIGN_PAYLOAD, so
		 * if we want to align the real payload, then we can
		 * just pretent we simply have two headers. */
		align = (long)wb->buf + 2*SSL3_RT_HEADER_LENGTH;
		align = (-align)&(SSL3_ALIGN_PAYLOAD-1);
#endif
		p = wb->buf + align;
		wb->offset  = align;
		}
	else if (prefix_len)
		{
		p = wb->buf + wb->offset + prefix_len;
		}
	else
		{
#if defined(SSL3_ALIGN_PAYLOAD) && SSL3_ALIGN_PAYLOAD!=0
		align = (long)wb->buf + SSL3_RT_HEADER_LENGTH;
		align = (-align)&(SSL3_ALIGN_PAYLOAD-1);
#endif
		p = wb->buf + align;
		wb->offset  = align;
		}

	/* write the header */

	*(p++)=type&0xff;
	wr->type=type;

	*(p++)=(s->version>>8);
	/* Some servers hang if iniatial client hello is larger than 256
	 * bytes and record version number > TLS 1.0
	 */
	if (s->state == SSL3_ST_CW_CLNT_HELLO_B
				&& !s->renegotiate
				&& TLS1_get_version(s) > TLS1_VERSION)
		*(p++) = 0x1;
	else
		*(p++)=s->version&0xff;

	/* field where we are to write out packet length */
	plen=p; 
	p+=2;
	/* Explicit IV length, block ciphers appropriate version flag */
	if (s->enc_write_ctx && SSL_USE_EXPLICIT_IV(s))
		{
		int mode = EVP_CIPHER_CTX_mode(s->enc_write_ctx);
		if (mode == EVP_CIPH_CBC_MODE)
			{
			eivlen = EVP_CIPHER_CTX_iv_length(s->enc_write_ctx);
			if (eivlen <= 1)
				eivlen = 0;
			}
		/* Need explicit part of IV for GCM mode */
		else if (mode == EVP_CIPH_GCM_MODE)
			eivlen = EVP_GCM_TLS_EXPLICIT_IV_LEN;
		else
			eivlen = 0;
		}
	else 
		eivlen = 0;

	/* lets setup the record stuff. */
	wr->data=p + eivlen;
	wr->length=(int)len;
	wr->input=(unsigned char *)buf;

	/* we now 'read' from wr->input, wr->length bytes into
	 * wr->data */

	/* first we compress */
	if (s->compress != NULL)
		{
		if (!ssl3_do_compress(s))
			{
			SSLerr(SSL_F_DO_SSL3_WRITE,SSL_R_COMPRESSION_FAILURE);
			goto err;
			}
		}
	else
		{
		memcpy(wr->data,wr->input,wr->length);
		wr->input=wr->data;
		}

	/* we should still have the output to wr->data and the input
	 * from wr->input.  Length should be wr->length.
	 * wr->data still points in the wb->buf */

	if (!SSL_USE_ETM(s) && mac_size != 0)
		{
		if (s->method->ssl3_enc->mac(s,&(p[wr->length + eivlen]),1) < 0)
			goto err;
		wr->length+=mac_size;
		}

	wr->input=p;
	wr->data=p;

	if (eivlen)
		{
	/*	if (RAND_pseudo_bytes(p, eivlen) <= 0)
			goto err; */
		wr->length += eivlen;
		}

	/* ssl3_enc can only have an error on read */
	s->method->ssl3_enc->enc(s,1);

	if (SSL_USE_ETM(s) && mac_size != 0)
		{
		if (s->method->ssl3_enc->mac(s,p + wr->length,1) < 0)
			goto err;
		wr->length+=mac_size;
		}

	/* record length after mac and block padding */
	s2n(wr->length,plen);

	if (s->msg_callback)
		s->msg_callback(1, 0, SSL3_RT_HEADER, plen - 5, 5, s, s->msg_callback_arg);

	/* we should now have
	 * wr->data pointing to the encrypted data, which is
	 * wr->length long */
	wr->type=type; /* not needed but helps for debugging */
	wr->length+=SSL3_RT_HEADER_LENGTH;

	if (create_empty_fragment)
		{
		/* we are in a recursive call;
		 * just return the length, don't write out anything here
		 */
		return wr->length;
		}

	/* now let's set up wb */
	wb->left = prefix_len + wr->length;

	/* memorize arguments so that ssl3_write_pending can detect bad write retries later */
	s->s3->wpend_tot=len;
	s->s3->wpend_buf=buf;
	s->s3->wpend_type=type;
	s->s3->wpend_ret=len;

	/* we now just need to write the buffer */
	return ssl3_write_pending(s,type,buf,len);
err:
	return -1;
	}

/* if s->s3->wbuf.left != 0, we need to call this */
int ssl3_write_pending(SSL *s, int type, const unsigned char *buf,
	unsigned int len)
	{
	int i;
	SSL3_BUFFER *wb=&(s->s3->wbuf);

/* XXXX */
	if ((s->s3->wpend_tot > (int)len)
		|| ((s->s3->wpend_buf != buf) &&
			!(s->mode & SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER))
		|| (s->s3->wpend_type != type))
		{
		SSLerr(SSL_F_SSL3_WRITE_PENDING,SSL_R_BAD_WRITE_RETRY);
		return(-1);
		}

	for (;;)
		{
		clear_sys_error();
		if (s->wbio != NULL)
			{
			s->rwstate=SSL_WRITING;
			i=BIO_write(s->wbio,
				(char *)&(wb->buf[wb->offset]),
				(unsigned int)wb->left);
			}
		else
			{
			SSLerr(SSL_F_SSL3_WRITE_PENDING,SSL_R_BIO_NOT_SET);
			i= -1;
			}
		if (i == wb->left)
			{
			wb->left=0;
			wb->offset+=i;
			s->rwstate=SSL_NOTHING;
			return(s->s3->wpend_ret);
			}
		else if (i <= 0) {
			if (s->version == DTLS1_VERSION ||
			    s->version == DTLS1_BAD_VER) {
				/* For DTLS, just drop it. That's kind of the whole
				   point in using a datagram service */
				wb->left = 0;
			}
			return(i);
		}
		wb->offset+=i;
		wb->left-=i;
		}
	}

/* Return up to 'len' payload bytes received in 'type' records.
 * 'type' is one of the following:
 *
 *   -  SSL3_RT_HANDSHAKE (when ssl3_get_message calls us)
 *   -  SSL3_RT_APPLICATION_DATA (when ssl3_read calls us)
 *   -  0 (during a shutdown, no data has to be returned)
 *
 * If we don't have stored data to work from, read a SSL/TLS record first
 * (possibly multiple records if we still don't have anything to return).
 *
 * This function must handle any surprises the peer may have for us, such as
 * Alert records (e.g. close_notify), ChangeCipherSpec records (not really
 * a surprise, but handled as if it were), or renegotiation requests.
 * Also if record payloads contain fragments too small to process, we store
 * them until there is enough for the respective protocol (the record protocol
 * may use arbitrary fragmentation and even interleaving):
 *     Change cipher spec protocol
 *             just 1 byte needed, no need for keeping anything stored
 *     Alert protocol
 *             2 bytes needed (AlertLevel, AlertDescription)
 *     Handshake protocol
 *             4 bytes needed (HandshakeType, uint24 length) -- we just have
 *             to detect unexpected Client Hello and Hello Request messages
 *             here, anything else is handled by higher layers
 *     Application data protocol
 *             none of our business
 */
int ssl3_read_bytes(SSL *s, int type, unsigned char *buf, int len, int peek)
	{
	int al,i,j,ret;
	unsigned int n;
	SSL3_RECORD *rr;
	void (*cb)(const SSL *ssl,int type2,int val)=NULL;

	if (s->s3->rbuf.buf == NULL) /* Not initialized yet */
		if (!ssl3_setup_read_buffer(s))
			return(-1);

	if ((type && (type != SSL3_RT_APPLICATION_DATA) && (type != SSL3_RT_HANDSHAKE)) ||
	    (peek && (type != SSL3_RT_APPLICATION_DATA)))
		{
		SSLerr(SSL_F_SSL3_READ_BYTES, ERR_R_INTERNAL_ERROR);
		return -1;
		}

	if ((type == SSL3_RT_HANDSHAKE) && (s->s3->handshake_fragment_len > 0))
		/* (partially) satisfy request from storage */
		{
		unsigned char *src = s->s3->handshake_fragment;
		unsigned char *dst = buf;
		unsigned int k;

		/* peek == 0 */
		n = 0;
		while ((len > 0) && (s->s3->handshake_fragment_len > 0))
			{
			*dst++ = *src++;
			len--; s->s3->handshake_fragment_len--;
			n++;
			}
		/* move any remaining fragment bytes: */
		for (k = 0; k < s->s3->handshake_fragment_len; k++)
			s->s3->handshake_fragment[k] = *src++;
		return n;
	}

	/* Now s->s3->handshake_fragment_len == 0 if type == SSL3_RT_HANDSHAKE. */

	if (!s->in_handshake && SSL_in_init(s))
		{
		/* type == SSL3_RT_APPLICATION_DATA */
		i=s->handshake_func(s);
		if (i < 0) return(i);
		if (i == 0)
			{
			SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_SSL_HANDSHAKE_FAILURE);
			return(-1);
			}
		}
start:
	s->rwstate=SSL_NOTHING;

	/* s->s3->rrec.type	    - is the type of record
	 * s->s3->rrec.data,    - data
	 * s->s3->rrec.off,     - offset into 'data' for next read
	 * s->s3->rrec.length,  - number of bytes. */
	rr = &(s->s3->rrec);

	/* get new packet if necessary */
	if ((rr->length == 0) || (s->rstate == SSL_ST_READ_BODY))
		{
		ret=ssl3_get_record(s);
		if (ret <= 0) return(ret);
		}

	/* we now have a packet which can be read and processed */

	if (s->s3->change_cipher_spec /* set when we receive ChangeCipherSpec,
	                               * reset by ssl3_get_finished */
		&& (rr->type != SSL3_RT_HANDSHAKE))
		{
		al=SSL_AD_UNEXPECTED_MESSAGE;
		SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_DATA_BETWEEN_CCS_AND_FINISHED);
		goto f_err;
		}

	/* If the other end has shut down, throw anything we read away
	 * (even in 'peek' mode) */
	if (s->shutdown & SSL_RECEIVED_SHUTDOWN)
		{
		rr->length=0;
		s->rwstate=SSL_NOTHING;
		return(0);
		}


	if (type == rr->type) /* SSL3_RT_APPLICATION_DATA or SSL3_RT_HANDSHAKE */
		{
		/* make sure that we are not getting application data when we
		 * are doing a handshake for the first time */
		if (SSL_in_init(s) && (type == SSL3_RT_APPLICATION_DATA) &&
			(s->enc_read_ctx == NULL))
			{
			al=SSL_AD_UNEXPECTED_MESSAGE;
			SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_APP_DATA_IN_HANDSHAKE);
			goto f_err;
			}

		if (len <= 0) return(len);

		if ((unsigned int)len > rr->length)
			n = rr->length;
		else
			n = (unsigned int)len;

		memcpy(buf,&(rr->data[rr->off]),n);
		if (!peek)
			{
			rr->length-=n;
			rr->off+=n;
			if (rr->length == 0)
				{
				s->rstate=SSL_ST_READ_HEADER;
				rr->off=0;
				if (s->mode & SSL_MODE_RELEASE_BUFFERS && s->s3->rbuf.left == 0)
					ssl3_release_read_buffer(s);
				}
			}
		return(n);
		}


	/* If we get here, then type != rr->type; if we have a handshake
	 * message, then it was unexpected (Hello Request or Client Hello). */

	/* In case of record types for which we have 'fragment' storage,
	 * fill that so that we can process the data at a fixed place.
	 */
		{
		unsigned int dest_maxlen = 0;
		unsigned char *dest = NULL;
		unsigned int *dest_len = NULL;

		if (rr->type == SSL3_RT_HANDSHAKE)
			{
			dest_maxlen = sizeof s->s3->handshake_fragment;
			dest = s->s3->handshake_fragment;
			dest_len = &s->s3->handshake_fragment_len;
			}
		else if (rr->type == SSL3_RT_ALERT)
			{
			dest_maxlen = sizeof s->s3->alert_fragment;
			dest = s->s3->alert_fragment;
			dest_len = &s->s3->alert_fragment_len;
			}
#ifndef OPENSSL_NO_HEARTBEATS
		else if (rr->type == TLS1_RT_HEARTBEAT)
			{
			tls1_process_heartbeat(s);

			/* Exit and notify application to read again */
			rr->length = 0;
			s->rwstate=SSL_READING;
			BIO_clear_retry_flags(SSL_get_rbio(s));
			BIO_set_retry_read(SSL_get_rbio(s));
			return(-1);
			}
#endif

		if (dest_maxlen > 0)
			{
			n = dest_maxlen - *dest_len; /* available space in 'dest' */
			if (rr->length < n)
				n = rr->length; /* available bytes */

			/* now move 'n' bytes: */
			while (n-- > 0)
				{
				dest[(*dest_len)++] = rr->data[rr->off++];
				rr->length--;
				}

			if (*dest_len < dest_maxlen)
				goto start; /* fragment was too small */
			}
		}

	/* s->s3->handshake_fragment_len == 4  iff  rr->type == SSL3_RT_HANDSHAKE;
	 * s->s3->alert_fragment_len == 2      iff  rr->type == SSL3_RT_ALERT.
	 * (Possibly rr is 'empty' now, i.e. rr->length may be 0.) */

	/* If we are a client, check for an incoming 'Hello Request': */
	if ((!s->server) &&
		(s->s3->handshake_fragment_len >= 4) &&
		(s->s3->handshake_fragment[0] == SSL3_MT_HELLO_REQUEST) &&
		(s->session != NULL) && (s->session->cipher != NULL))
		{
		s->s3->handshake_fragment_len = 0;

		if ((s->s3->handshake_fragment[1] != 0) ||
			(s->s3->handshake_fragment[2] != 0) ||
			(s->s3->handshake_fragment[3] != 0))
			{
			al=SSL_AD_DECODE_ERROR;
			SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_BAD_HELLO_REQUEST);
			goto f_err;
			}

		if (s->msg_callback)
			s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, s->s3->handshake_fragment, 4, s, s->msg_callback_arg);

		if (SSL_is_init_finished(s) &&
			!(s->s3->flags & SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS) &&
			!s->s3->renegotiate)
			{
			ssl3_renegotiate(s);
			if (ssl3_renegotiate_check(s))
				{
				i=s->handshake_func(s);
				if (i < 0) return(i);
				if (i == 0)
					{
					SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_SSL_HANDSHAKE_FAILURE);
					return(-1);
					}

				if (!(s->mode & SSL_MODE_AUTO_RETRY))
					{
					if (s->s3->rbuf.left == 0) /* no read-ahead left? */
						{
						BIO *bio;
						/* In the case where we try to read application data,
						 * but we trigger an SSL handshake, we return -1 with
						 * the retry option set.  Otherwise renegotiation may
						 * cause nasty problems in the blocking world */
						s->rwstate=SSL_READING;
						bio=SSL_get_rbio(s);
						BIO_clear_retry_flags(bio);
						BIO_set_retry_read(bio);
						return(-1);
						}
					}
				}
			}
		/* we either finished a handshake or ignored the request,
		 * now try again to obtain the (application) data we were asked for */
		goto start;
		}
	/* If we are a server and get a client hello when renegotiation isn't
	 * allowed send back a no renegotiation alert and carry on.
	 * WARNING: experimental code, needs reviewing (steve)
	 */
	if (s->server &&
		SSL_is_init_finished(s) &&
    		!s->s3->send_connection_binding &&
		(s->version > SSL3_VERSION) &&
		(s->s3->handshake_fragment_len >= 4) &&
		(s->s3->handshake_fragment[0] == SSL3_MT_CLIENT_HELLO) &&
		(s->session != NULL) && (s->session->cipher != NULL) &&
		!(s->ctx->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION))
		
		{
		/*s->s3->handshake_fragment_len = 0;*/
		rr->length = 0;
		ssl3_send_alert(s,SSL3_AL_WARNING, SSL_AD_NO_RENEGOTIATION);
		goto start;
		}
	if (s->s3->alert_fragment_len >= 2)
		{
		int alert_level = s->s3->alert_fragment[0];
		int alert_descr = s->s3->alert_fragment[1];

		s->s3->alert_fragment_len = 0;

		if (s->msg_callback)
			s->msg_callback(0, s->version, SSL3_RT_ALERT, s->s3->alert_fragment, 2, s, s->msg_callback_arg);

		if (s->info_callback != NULL)
			cb=s->info_callback;
		else if (s->ctx->info_callback != NULL)
			cb=s->ctx->info_callback;

		if (cb != NULL)
			{
			j = (alert_level << 8) | alert_descr;
			cb(s, SSL_CB_READ_ALERT, j);
			}

		if (alert_level == 1) /* warning */
			{
			s->s3->warn_alert = alert_descr;
			if (alert_descr == SSL_AD_CLOSE_NOTIFY)
				{
				s->shutdown |= SSL_RECEIVED_SHUTDOWN;
				return(0);
				}
			/* This is a warning but we receive it if we requested
			 * renegotiation and the peer denied it. Terminate with
			 * a fatal alert because if application tried to
			 * renegotiatie it presumably had a good reason and
			 * expects it to succeed.
			 *
			 * In future we might have a renegotiation where we
			 * don't care if the peer refused it where we carry on.
			 */
			else if (alert_descr == SSL_AD_NO_RENEGOTIATION)
				{
				al = SSL_AD_HANDSHAKE_FAILURE;
				SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_NO_RENEGOTIATION);
				goto f_err;
				}
#ifdef SSL_AD_MISSING_SRP_USERNAME
			else if (alert_descr == SSL_AD_MISSING_SRP_USERNAME)
				return(0);
#endif
			}
		else if (alert_level == 2) /* fatal */
			{
			char tmp[16];

			s->rwstate=SSL_NOTHING;
			s->s3->fatal_alert = alert_descr;
			SSLerr(SSL_F_SSL3_READ_BYTES, SSL_AD_REASON_OFFSET + alert_descr);
			BIO_snprintf(tmp,sizeof tmp,"%d",alert_descr);
			ERR_add_error_data(2,"SSL alert number ",tmp);
			s->shutdown|=SSL_RECEIVED_SHUTDOWN;
			SSL_CTX_remove_session(s->ctx,s->session);
			return(0);
			}
		else
			{
			al=SSL_AD_ILLEGAL_PARAMETER;
			SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_UNKNOWN_ALERT_TYPE);
			goto f_err;
			}

		goto start;
		}

	if (s->shutdown & SSL_SENT_SHUTDOWN) /* but we have not received a shutdown */
		{
		s->rwstate=SSL_NOTHING;
		rr->length=0;
		return(0);
		}

	if (rr->type == SSL3_RT_CHANGE_CIPHER_SPEC)
		{
		/* 'Change Cipher Spec' is just a single byte, so we know
		 * exactly what the record payload has to look like */
		if (	(rr->length != 1) || (rr->off != 0) ||
			(rr->data[0] != SSL3_MT_CCS))
			{
			al=SSL_AD_ILLEGAL_PARAMETER;
			SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_BAD_CHANGE_CIPHER_SPEC);
			goto f_err;
			}

		/* Check we have a cipher to change to */
		if (s->s3->tmp.new_cipher == NULL)
			{
			al=SSL_AD_UNEXPECTED_MESSAGE;
			SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_CCS_RECEIVED_EARLY);
			goto f_err;
			}

		if (!(s->s3->flags & SSL3_FLAGS_CCS_OK))
			{
			al=SSL_AD_UNEXPECTED_MESSAGE;
			SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_CCS_RECEIVED_EARLY);
			goto f_err;
			}

		s->s3->flags &= ~SSL3_FLAGS_CCS_OK;

		rr->length=0;

		if (s->msg_callback)
			s->msg_callback(0, s->version, SSL3_RT_CHANGE_CIPHER_SPEC, rr->data, 1, s, s->msg_callback_arg);

		s->s3->change_cipher_spec=1;
		if (!ssl3_do_change_cipher_spec(s))
			goto err;
		else
			goto start;
		}

	/* Unexpected handshake message (Client Hello, or protocol violation) */
	if ((s->s3->handshake_fragment_len >= 4) &&	!s->in_handshake)
		{
		if (((s->state&SSL_ST_MASK) == SSL_ST_OK) &&
			!(s->s3->flags & SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS))
			{
#if 0 /* worked only because C operator preferences are not as expected (and
       * because this is not really needed for clients except for detecting
       * protocol violations): */
			s->state=SSL_ST_BEFORE|(s->server)
				?SSL_ST_ACCEPT
				:SSL_ST_CONNECT;
#else
			s->state = s->server ? SSL_ST_ACCEPT : SSL_ST_CONNECT;
#endif
			s->renegotiate=1;
			s->new_session=1;
			}
		i=s->handshake_func(s);
		if (i < 0) return(i);
		if (i == 0)
			{
			SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_SSL_HANDSHAKE_FAILURE);
			return(-1);
			}

		if (!(s->mode & SSL_MODE_AUTO_RETRY))
			{
			if (s->s3->rbuf.left == 0) /* no read-ahead left? */
				{
				BIO *bio;
				/* In the case where we try to read application data,
				 * but we trigger an SSL handshake, we return -1 with
				 * the retry option set.  Otherwise renegotiation may
				 * cause nasty problems in the blocking world */
				s->rwstate=SSL_READING;
				bio=SSL_get_rbio(s);
				BIO_clear_retry_flags(bio);
				BIO_set_retry_read(bio);
				return(-1);
				}
			}
		goto start;
		}

	switch (rr->type)
		{
	default:
#ifndef OPENSSL_NO_TLS
		/* TLS up to v1.1 just ignores unknown message types:
		 * TLS v1.2 give an unexpected message alert.
		 */
		if (s->version >= TLS1_VERSION && s->version <= TLS1_1_VERSION)
			{
			rr->length = 0;
			goto start;
			}
#endif
		al=SSL_AD_UNEXPECTED_MESSAGE;
		SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_UNEXPECTED_RECORD);
		goto f_err;
	case SSL3_RT_CHANGE_CIPHER_SPEC:
	case SSL3_RT_ALERT:
	case SSL3_RT_HANDSHAKE:
		/* we already handled all of these, with the possible exception
		 * of SSL3_RT_HANDSHAKE when s->in_handshake is set, but that
		 * should not happen when type != rr->type */
		al=SSL_AD_UNEXPECTED_MESSAGE;
		SSLerr(SSL_F_SSL3_READ_BYTES,ERR_R_INTERNAL_ERROR);
		goto f_err;
	case SSL3_RT_APPLICATION_DATA:
		/* At this point, we were expecting handshake data,
		 * but have application data.  If the library was
		 * running inside ssl3_read() (i.e. in_read_app_data
		 * is set) and it makes sense to read application data
		 * at this point (session renegotiation not yet started),
		 * we will indulge it.
		 */
		if (s->s3->in_read_app_data &&
			(s->s3->total_renegotiations != 0) &&
			((
				(s->state & SSL_ST_CONNECT) &&
				(s->state >= SSL3_ST_CW_CLNT_HELLO_A) &&
				(s->state <= SSL3_ST_CR_SRVR_HELLO_A)
				) || (
					(s->state & SSL_ST_ACCEPT) &&
					(s->state <= SSL3_ST_SW_HELLO_REQ_A) &&
					(s->state >= SSL3_ST_SR_CLNT_HELLO_A)
					)
				))
			{
			s->s3->in_read_app_data=2;
			return(-1);
			}
		else
			{
			al=SSL_AD_UNEXPECTED_MESSAGE;
			SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_UNEXPECTED_RECORD);
			goto f_err;
			}
		}
	/* not reached */

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

int ssl3_do_change_cipher_spec(SSL *s)
	{
	int i;
	const char *sender;
	int slen;

	if (s->state & SSL_ST_ACCEPT)
		i=SSL3_CHANGE_CIPHER_SERVER_READ;
	else
		i=SSL3_CHANGE_CIPHER_CLIENT_READ;

	if (s->s3->tmp.key_block == NULL)
		{
		if (s->session == NULL || s->session->master_key_length == 0)
			{
			/* might happen if dtls1_read_bytes() calls this */
			SSLerr(SSL_F_SSL3_DO_CHANGE_CIPHER_SPEC,SSL_R_CCS_RECEIVED_EARLY);
			return (0);
			}

		s->session->cipher=s->s3->tmp.new_cipher;
		if (!s->method->ssl3_enc->setup_key_block(s)) return(0);
		}

	if (!s->method->ssl3_enc->change_cipher_state(s,i))
		return(0);

	/* we have to record the message digest at
	 * this point so we can get it before we read
	 * the finished message */
	if (s->state & SSL_ST_CONNECT)
		{
		sender=s->method->ssl3_enc->server_finished_label;
		slen=s->method->ssl3_enc->server_finished_label_len;
		}
	else
		{
		sender=s->method->ssl3_enc->client_finished_label;
		slen=s->method->ssl3_enc->client_finished_label_len;
		}

	i = s->method->ssl3_enc->final_finish_mac(s,
		sender,slen,s->s3->tmp.peer_finish_md);
	if (i == 0)
		{
		SSLerr(SSL_F_SSL3_DO_CHANGE_CIPHER_SPEC, ERR_R_INTERNAL_ERROR);
		return 0;
		}
	s->s3->tmp.peer_finish_md_len = i;

	return(1);
	}

int ssl3_send_alert(SSL *s, int level, int desc)
	{
	/* Map tls/ssl alert value to correct one */
	desc=s->method->ssl3_enc->alert_value(desc);
	if (s->version == SSL3_VERSION && desc == SSL_AD_PROTOCOL_VERSION)
		desc = SSL_AD_HANDSHAKE_FAILURE; /* SSL 3.0 does not have protocol_version alerts */
	if (desc < 0) return -1;
	/* If a fatal one, remove from cache */
	if ((level == SSL3_AL_FATAL) && (s->session != NULL))
		SSL_CTX_remove_session(s->ctx,s->session);

	s->s3->alert_dispatch=1;
	s->s3->send_alert[0]=level;
	s->s3->send_alert[1]=desc;
	if (s->s3->wbuf.left == 0) /* data still being written out? */
		return s->method->ssl_dispatch_alert(s);
	/* else data is still being written out, we will get written
	 * some time in the future */
	return -1;
	}

int ssl3_dispatch_alert(SSL *s)
	{
	int i,j;
	void (*cb)(const SSL *ssl,int type,int val)=NULL;

	s->s3->alert_dispatch=0;
	i = do_ssl3_write(s, SSL3_RT_ALERT, &s->s3->send_alert[0], 2, 0);
	if (i <= 0)
		{
		s->s3->alert_dispatch=1;
		}
	else
		{
		/* Alert sent to BIO.  If it is important, flush it now.
		 * If the message does not get sent due to non-blocking IO,
		 * we will not worry too much. */
		if (s->s3->send_alert[0] == SSL3_AL_FATAL)
			(void)BIO_flush(s->wbio);

		if (s->msg_callback)
			s->msg_callback(1, s->version, SSL3_RT_ALERT, s->s3->send_alert, 2, s, s->msg_callback_arg);

		if (s->info_callback != NULL)
			cb=s->info_callback;
		else if (s->ctx->info_callback != NULL)
			cb=s->ctx->info_callback;

		if (cb != NULL)
			{
			j=(s->s3->send_alert[0]<<8)|s->s3->send_alert[1];
			cb(s,SSL_CB_WRITE_ALERT,j);
			}
		}
	return(i);
	}