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

static int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
			 unsigned int len, int create_empty_fragment);
static int ssl3_write_pending(SSL *s, int type, const unsigned char *buf,
			      unsigned int len);
static int ssl3_get_record(SSL *s);
static int do_compress(SSL *ssl);
static int do_uncompress(SSL *ssl);
static int do_change_cipher_spec(SSL *ssl);

/* used only by ssl3_get_record */
static 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,off,newb;

	if (!extend)
		{
		/* start with empty packet ... */
		if (s->s3->rbuf.left == 0)
			s->s3->rbuf.offset = 0;
		s->packet = s->s3->rbuf.buf + s->s3->rbuf.offset;
		s->packet_length = 0;
		/* ... now we can act as if 'extend' was set */
		}

	/* if there is enough in the buffer from a previous read, take some */
	if (s->s3->rbuf.left >= (int)n)
		{
		s->packet_length+=n;
		s->s3->rbuf.left-=n;
		s->s3->rbuf.offset+=n;
		return(n);
		}

	/* else we need to read more data */
	if (!s->read_ahead)
		max=n;

	{
		/* avoid buffer overflow */
		int max_max = s->s3->rbuf.len - s->packet_length;
		if (max > max_max)
			max = max_max;
	}
	if (n > max) /* does not happen */
		{
		SSLerr(SSL_F_SSL3_READ_N,ERR_R_INTERNAL_ERROR);
		return -1;
		}

	off = s->packet_length;
	newb = s->s3->rbuf.left;
	/* Move any available bytes to front of buffer:
	 * 'off' bytes already pointed to by 'packet',
	 * 'newb' extra ones at the end */
	if (s->packet != s->s3->rbuf.buf)
		{
		/*  off > 0 */
		memmove(s->s3->rbuf.buf, s->packet, off+newb);
		s->packet = s->s3->rbuf.buf;
		}

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

		clear_sys_error();
		if (s->rbio != NULL)
			{
			s->rwstate=SSL_READING;
			i=BIO_read(s->rbio,	&(s->s3->rbuf.buf[off+newb]), max-newb);
			}
		else
			{
			SSLerr(SSL_F_SSL3_READ_N,SSL_R_READ_BIO_NOT_SET);
			i = -1;
			}

		if (i <= 0)
			{
			s->s3->rbuf.left = newb;
			return(i);
			}
		newb+=i;
		}

	/* done reading, now the book-keeping */
	s->s3->rbuf.offset = off + n;
	s->s3->rbuf.left = newb - n;
	s->packet_length += n;
	s->rwstate=SSL_NOTHING;
	return(n);
	}

/* 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 int mac_size;
	int clear=0;
	size_t extra;
	int decryption_failed_or_bad_record_mac = 0;
	unsigned char *mac = NULL;

	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->rbuf.len - SSL3_RT_MAX_PACKET_SIZE)
		{
		/* actually likely 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;

		/* 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);

		/* Lets check version */
		if (s->first_packet)
			{
			s->first_packet=0;
			}
		else
			{
			if (version != s->version)
				{
				SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_WRONG_VERSION_NUMBER);
				/* Send back error using their
				 * version number :-) */
				s->version=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 > SSL3_RT_MAX_ENCRYPTED_LENGTH+extra)
			{
			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;

	enc_err = s->method->ssl3_enc->enc(s,0);
	if (enc_err <= 0)
		{
		if (enc_err == 0)
			/* SSLerr() and ssl3_send_alert() have been called */
			goto err;

		/* Otherwise enc_err == -1, which indicates bad padding
		 * (rec->length has not been changed in this case).
		 * To minimize information leaked via timing, we will perform
		 * the MAC computation anyway. */
		decryption_failed_or_bad_record_mac = 1;
		}

#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) ||
		(s->read_hash == NULL))
		clear=1;

	if (!clear)
		{
		mac_size=EVP_MD_size(s->read_hash);

		if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH+extra+mac_size)
			{
#if 0 /* OK only for stream ciphers (then rr->length is visible from ciphertext anyway) */
			al=SSL_AD_RECORD_OVERFLOW;
			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_PRE_MAC_LENGTH_TOO_LONG);
			goto f_err;
#else
			decryption_failed_or_bad_record_mac = 1;
#endif			
			}
		/* check the MAC for rr->input (it's in mac_size bytes at the tail) */
		if (rr->length >= mac_size)
			{
			rr->length -= mac_size;
			mac = &rr->data[rr->length];
			}
		else
			{
			/* record (minus padding) is too short to contain a MAC */
#if 0 /* OK only for stream ciphers */
			al=SSL_AD_DECODE_ERROR;
			SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_LENGTH_TOO_SHORT);
			goto f_err;
#else
			decryption_failed_or_bad_record_mac = 1;
			rr->length = 0;
#endif
			}
		i=s->method->ssl3_enc->mac(s,md,0);
		if (mac == NULL || memcmp(md, mac, mac_size) != 0)
			{
			decryption_failed_or_bad_record_mac = 1;
			}
		}

	if (decryption_failed_or_bad_record_mac)
		{
		/* 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 occured -- 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 (!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) goto again;

	return(1);

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

static int do_uncompress(SSL *ssl)
	{
	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;

	return(1);
	}

static int do_compress(SSL *ssl)
	{
	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;
	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_;
	unsigned int tot,n,nw;
	int i;

	s->rwstate=SSL_NOTHING;
	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;
			}
		}

	n=(len-tot);
	for (;;)
		{
		if (n > SSL3_RT_MAX_PLAIN_LENGTH)
			nw=SSL3_RT_MAX_PLAIN_LENGTH;
		else
			nw=n;

		i=do_ssl3_write(s, type, &(buf[tot]), nw, 0);
		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;
			
			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;
	SSL3_RECORD *wr;
	SSL3_BUFFER *wb;
	SSL_SESSION *sess;

	/* first check if there is a SSL3_BUFFER still being written
	 * out.  This will happen with non blocking IO */
	if (s->s3->wbuf.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=ssl3_dispatch_alert(s);
		if (i <= 0)
			return(i);
		/* if it went, fall through and send more stuff */
		}

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

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

	if (	(sess == NULL) ||
		(s->enc_write_ctx == NULL) ||
		(s->write_hash == NULL))
		clear=1;

	if (clear)
		mac_size=0;
	else
		mac_size=EVP_MD_size(s->write_hash);

	/* '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 (s->s3->wbuf.len < (size_t)prefix_len + SSL3_RT_MAX_PACKET_SIZE)
				{
				/* insufficient space */
				SSLerr(SSL_F_DO_SSL3_WRITE, ERR_R_INTERNAL_ERROR);
				goto err;
				}
			}
		
		s->s3->empty_fragment_done = 1;
		}

	p = wb->buf + prefix_len;

	/* write the header */

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

	*(p++)=(s->version>>8);
	*(p++)=s->version&0xff;

	/* field where we are to write out packet length */
	plen=p; 
	p+=2;

	/* lets setup the record stuff. */
	wr->data=p;
	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 (!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 (mac_size != 0)
		{
		s->method->ssl3_enc->mac(s,&(p[wr->length]),1);
		wr->length+=mac_size;
		wr->input=p;
		wr->data=p;
		}

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

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

	/* 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;
	wb->offset = 0;

	/* 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 */
static int ssl3_write_pending(SSL *s, int type, const unsigned char *buf,
			      unsigned int len)
	{
	int i;

/* 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 *)&(s->s3->wbuf.buf[s->s3->wbuf.offset]),
				(unsigned int)s->s3->wbuf.left);
			}
		else
			{
			SSLerr(SSL_F_SSL3_WRITE_PENDING,SSL_R_BIO_NOT_SET);
			i= -1;
			}
		if (i == s->s3->wbuf.left)
			{
			s->s3->wbuf.left=0;
			s->rwstate=SSL_NOTHING;
			return(s->s3->wpend_ret);
			}
		else if (i <= 0)
			return(i);
		s->s3->wbuf.offset+=i;
		s->s3->wbuf.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_buffers(s))
			return(-1);

	if ((type && (type != SSL3_RT_APPLICATION_DATA) && (type != SSL3_RT_HANDSHAKE) && type) ||
	    (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 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;
				}
			}
		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;
			}

		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 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 (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);
				}
			}
		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))
			{
			i=SSL_AD_ILLEGAL_PARAMETER;
			SSLerr(SSL_F_SSL3_READ_BYTES,SSL_R_BAD_CHANGE_CIPHER_SPEC);
			goto err;
			}

		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 (!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->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 just ignores unknown message types */
		if (s->version == TLS1_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);
	}

static int 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)
		{
		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;
		}

	s->s3->tmp.peer_finish_md_len = s->method->ssl3_enc->final_finish_mac(s,
		&(s->s3->finish_dgst1),
		&(s->s3->finish_dgst2),
		sender,slen,s->s3->tmp.peer_finish_md);

	return(1);
	}

void 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;
	/* If a fatal one, remove from cache */
	if ((level == 2) && (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? */
		ssl3_dispatch_alert(s);
	/* else data is still being written out, we will get written
	 * some time in the future */
	}

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);
	}