s2_pkt.c

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/* ssl/s2_pkt.c */
/* Copyright (C) 1995-1998 Eric Young ([e-mail])
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young ([e-mail]).
 * 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 ([e-mail]).
 * 
 * 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 ([e-mail])"
 *    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 ([e-mail])"
 * 
 * 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.]
 */

#include "ssl_locl.h"
#ifndef NO_SSL2
#include <stdio.h>
#include <errno.h>
#define USE_SOCKETS

static int read_n(SSL *s,unsigned int n,unsigned int max,unsigned int extend);
static int do_ssl_write(SSL *s, const unsigned char *buf, unsigned int len);
static int write_pending(SSL *s, const unsigned char *buf, unsigned int len);
static int ssl_mt_error(int n);
int ssl2_peek(SSL *s, char *buf, int len)
	{
	int ret;

	ret=ssl2_read(s,buf,len);
	if (ret > 0)
	        {
		s->s2->ract_data_length+=ret;
		s->s2->ract_data-=ret;
		}
	return(ret);
	}

/* SSL_read -
 * This routine will return 0 to len bytes, decrypted etc if required.
 */
int ssl2_read(SSL *s, void *buf, int len)
	{
	int n;
	unsigned char mac[MAX_MAC_SIZE];
	unsigned char *p;
	int i;
	unsigned int mac_size=0;

ssl2_read_again:
	if (SSL_in_init(s) && !s->in_handshake)
		{
		n=s->handshake_func(s);
		if (n < 0) return(n);
		if (n == 0)
			{
			SSLerr(SSL_F_SSL2_READ,SSL_R_SSL_HANDSHAKE_FAILURE);
			return(-1);
			}
		}

	clear_sys_error();
	s->rwstate=SSL_NOTHING;
	if (len <= 0) return(len);

	if (s->s2->ract_data_length != 0) /* read from buffer */
		{
		if (len > s->s2->ract_data_length)
			n=s->s2->ract_data_length;
		else
			n=len;

		memcpy(buf,s->s2->ract_data,(unsigned int)n);
		s->s2->ract_data_length-=n;
		s->s2->ract_data+=n;
		if (s->s2->ract_data_length == 0)
			s->rstate=SSL_ST_READ_HEADER;
		return(n);
		}

	if (s->rstate == SSL_ST_READ_HEADER)
		{
		if (s->first_packet)
			{
			n=read_n(s,5,SSL2_MAX_RECORD_LENGTH_2_BYTE_HEADER+2,0);
			if (n <= 0) return(n); /* error or non-blocking */
			s->first_packet=0;
			p=s->packet;
			if (!((p[0] & 0x80) && (
				(p[2] == SSL2_MT_CLIENT_HELLO) ||
				(p[2] == SSL2_MT_SERVER_HELLO))))
				{
				SSLerr(SSL_F_SSL2_READ,SSL_R_NON_SSLV2_INITIAL_PACKET);
				return(-1);
				}
			}
		else
			{
			n=read_n(s,2,SSL2_MAX_RECORD_LENGTH_2_BYTE_HEADER+2,0);
			if (n <= 0) return(n); /* error or non-blocking */
			}
		/* part read stuff */

		s->rstate=SSL_ST_READ_BODY;
		p=s->packet;
		/* Do header */
		/*s->s2->padding=0;*/
		s->s2->escape=0;
		s->s2->rlength=(((unsigned int)p[0])<<8)|((unsigned int)p[1]);
		if ((p[0] & TWO_BYTE_BIT))		/* Two byte header? */
			{
			s->s2->three_byte_header=0;
			s->s2->rlength&=TWO_BYTE_MASK;	
			}
		else
			{
			s->s2->three_byte_header=1;
			s->s2->rlength&=THREE_BYTE_MASK;

			/* security >s2->escape */
			s->s2->escape=((p[0] & SEC_ESC_BIT))?1:0;
			}
		}

	if (s->rstate == SSL_ST_READ_BODY)
		{
		n=s->s2->rlength+2+s->s2->three_byte_header;
		if (n > (int)s->packet_length)
			{
			n-=s->packet_length;
			i=read_n(s,(unsigned int)n,(unsigned int)n,1);
			if (i <= 0) return(i); /* ERROR */
			}

		p= &(s->packet[2]);
		s->rstate=SSL_ST_READ_HEADER;
		if (s->s2->three_byte_header)
			s->s2->padding= *(p++);
		else	s->s2->padding=0;

		/* Data portion */
		if (s->s2->clear_text)
			{
			s->s2->mac_data=p;
			s->s2->ract_data=p;
			s->s2->pad_data=NULL;
			}
		else
			{
			mac_size=EVP_MD_size(s->read_hash);
			s->s2->mac_data=p;
			s->s2->ract_data= &p[mac_size];
			s->s2->pad_data= &p[mac_size+
				s->s2->rlength-s->s2->padding];
			}

		s->s2->ract_data_length=s->s2->rlength;
		/* added a check for length > max_size in case
		 * encryption was not turned on yet due to an error */
		if ((!s->s2->clear_text) &&
			(s->s2->rlength >= mac_size))
			{
			ssl2_enc(s,0);
			s->s2->ract_data_length-=mac_size;
			ssl2_mac(s,mac,0);
			s->s2->ract_data_length-=s->s2->padding;
			if (	(memcmp(mac,s->s2->mac_data,
				(unsigned int)mac_size) != 0) ||
				(s->s2->rlength%EVP_CIPHER_CTX_block_size(s->enc_read_ctx) != 0))
				{
				SSLerr(SSL_F_SSL2_READ,SSL_R_BAD_MAC_DECODE);
				return(-1);
				}
			}
		INC32(s->s2->read_sequence); /* expect next number */
		/* s->s2->ract_data is now available for processing */

#if 1
		/* How should we react when a packet containing 0
		 * bytes is received?  (Note that SSLeay/OpenSSL itself
		 * never sends such packets; see ssl2_write.)
		 * Returning 0 would be interpreted by the caller as
		 * indicating EOF, so it's not a good idea.
		 * Instead, we just continue reading.  Note that using
		 * select() for blocking sockets *never* guarantees
		 * that the next SSL_read will not block -- the available
		 * data may contain incomplete packets, and except for SSL 2
		 * renegotiation can confuse things even more. */

		goto ssl2_read_again; /* This should really be
				       * "return ssl2_read(s,buf,len)",
				       * but that would allow for
				       * denial-of-service attacks if a
				       * C compiler is used that does not
				       * recognize end-recursion. */
#else
		/* If a 0 byte packet was sent, return 0, otherwise
		 * we play havoc with people using select with
		 * blocking sockets.  Let them handle a packet at a time,
		 * they should really be using non-blocking sockets. */
		if (s->s2->ract_data_length == 0)
			return(0);
		return(ssl2_read(s,buf,len));
#endif
		}
	else
		{
		SSLerr(SSL_F_SSL2_READ,SSL_R_BAD_STATE);
			return(-1);
		}
	}

static int read_n(SSL *s, unsigned int n, unsigned int max,
	     unsigned int extend)
	{
	int i,off,newb;

	/* if there is stuff still in the buffer from a previous read,
	 * and there is more than we want, take some. */
	if (s->s2->rbuf_left >= (int)n)
		{
		if (extend)
			s->packet_length+=n;
		else
			{
			s->packet= &(s->s2->rbuf[s->s2->rbuf_offs]);
			s->packet_length=n;
			}
		s->s2->rbuf_left-=n;
		s->s2->rbuf_offs+=n;
		return(n);
		}

	if (!s->read_ahead) max=n;
	if (max > (unsigned int)(SSL2_MAX_RECORD_LENGTH_2_BYTE_HEADER+2))
		max=SSL2_MAX_RECORD_LENGTH_2_BYTE_HEADER+2;
	

	/* Else we want more than we have.
	 * First, if there is some left or we want to extend */
	off=0;
	if ((s->s2->rbuf_left != 0) || ((s->packet_length != 0) && extend))
		{
		newb=s->s2->rbuf_left;
		if (extend)
			{
			off=s->packet_length;
			if (s->packet != s->s2->rbuf)
				memcpy(s->s2->rbuf,s->packet,
					(unsigned int)newb+off);
			}
		else if (s->s2->rbuf_offs != 0)
			{
			memcpy(s->s2->rbuf,&(s->s2->rbuf[s->s2->rbuf_offs]),
				(unsigned int)newb);
			s->s2->rbuf_offs=0;
			}
		s->s2->rbuf_left=0;
		}
	else
		newb=0;

	/* off is the offset to start writing too.
	 * r->s2->rbuf_offs is the 'unread data', now 0. 
	 * newb is the number of new bytes so far
	 */
	s->packet=s->s2->rbuf;
	while (newb < (int)n)
		{
		clear_sys_error();
		if (s->rbio != NULL)
			{
			s->rwstate=SSL_READING;
			i=BIO_read(s->rbio,(char *)&(s->s2->rbuf[off+newb]),
				max-newb);
			}
		else
			{
			SSLerr(SSL_F_READ_N,SSL_R_READ_BIO_NOT_SET);
			i= -1;
			}
#ifdef PKT_DEBUG