enc_read.c revision 656d9c7f52f88b3a3daccafa7655dec086c4756e 
1/* crypto/des/enc_read.c */
2/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
3 * All rights reserved.
4 *
5 * This package is an SSL implementation written
6 * by Eric Young (eay@cryptsoft.com).
7 * The implementation was written so as to conform with Netscapes SSL.
8 *
9 * This library is free for commercial and non-commercial use as long as
10 * the following conditions are aheared to.  The following conditions
11 * apply to all code found in this distribution, be it the RC4, RSA,
12 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
13 * included with this distribution is covered by the same copyright terms
14 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
15 *
16 * Copyright remains Eric Young's, and as such any Copyright notices in
17 * the code are not to be removed.
18 * If this package is used in a product, Eric Young should be given attribution
19 * as the author of the parts of the library used.
20 * This can be in the form of a textual message at program startup or
21 * in documentation (online or textual) provided with the package.
22 *
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
25 * are met:
26 * 1. Redistributions of source code must retain the copyright
27 *    notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 *    notice, this list of conditions and the following disclaimer in the
30 *    documentation and/or other materials provided with the distribution.
31 * 3. All advertising materials mentioning features or use of this software
32 *    must display the following acknowledgement:
33 *    "This product includes cryptographic software written by
34 *     Eric Young (eay@cryptsoft.com)"
35 *    The word 'cryptographic' can be left out if the rouines from the library
36 *    being used are not cryptographic related :-).
37 * 4. If you include any Windows specific code (or a derivative thereof) from
38 *    the apps directory (application code) you must include an acknowledgement:
39 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
40 *
41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
51 * SUCH DAMAGE.
52 *
53 * The licence and distribution terms for any publically available version or
54 * derivative of this code cannot be changed.  i.e. this code cannot simply be
55 * copied and put under another distribution licence
56 * [including the GNU Public Licence.]
57 */
58
59#include <stdio.h>
60#include <errno.h>
61#include "cryptlib.h"
62#include "des_locl.h"
63
64/* This has some uglies in it but it works - even over sockets. */
65/*extern int errno;*/
66OPENSSL_IMPLEMENT_GLOBAL(int,DES_rw_mode)=DES_PCBC_MODE;
67
68
69/*
70 * WARNINGS:
71 *
72 *  -  The data format used by DES_enc_write() and DES_enc_read()
73 *     has a cryptographic weakness: When asked to write more
74 *     than MAXWRITE bytes, DES_enc_write will split the data
75 *     into several chunks that are all encrypted
76 *     using the same IV.  So don't use these functions unless you
77 *     are sure you know what you do (in which case you might
78 *     not want to use them anyway).
79 *
80 *  -  This code cannot handle non-blocking sockets.
81 *
82 *  -  This function uses an internal state and thus cannot be
83 *     used on multiple files.
84 */
85
86
87int DES_enc_read(int fd, void *buf, int len, DES_key_schedule *sched,
88		 DES_cblock *iv)
89	{
90	/* data to be unencrypted */
91	int net_num=0;
92	static unsigned char *net=NULL;
93	/* extra unencrypted data
94	 * for when a block of 100 comes in but is des_read one byte at
95	 * a time. */
96	static unsigned char *unnet=NULL;
97	static int unnet_start=0;
98	static int unnet_left=0;
99	static unsigned char *tmpbuf=NULL;
100	int i;
101	long num=0,rnum;
102	unsigned char *p;
103
104	if (tmpbuf == NULL)
105		{
106		tmpbuf=OPENSSL_malloc(BSIZE);
107		if (tmpbuf == NULL) return(-1);
108		}
109	if (net == NULL)
110		{
111		net=OPENSSL_malloc(BSIZE);
112		if (net == NULL) return(-1);
113		}
114	if (unnet == NULL)
115		{
116		unnet=OPENSSL_malloc(BSIZE);
117		if (unnet == NULL) return(-1);
118		}
119	/* left over data from last decrypt */
120	if (unnet_left != 0)
121		{
122		if (unnet_left < len)
123			{
124			/* we still still need more data but will return
125			 * with the number of bytes we have - should always
126			 * check the return value */
127			memcpy(buf,&(unnet[unnet_start]),
128			       unnet_left);
129			/* eay 26/08/92 I had the next 2 lines
130			 * reversed :-( */
131			i=unnet_left;
132			unnet_start=unnet_left=0;
133			}
134		else
135			{
136			memcpy(buf,&(unnet[unnet_start]),len);
137			unnet_start+=len;
138			unnet_left-=len;
139			i=len;
140			}
141		return(i);
142		}
143
144	/* We need to get more data. */
145	if (len > MAXWRITE) len=MAXWRITE;
146
147	/* first - get the length */
148	while (net_num < HDRSIZE)
149		{
150		i=read(fd,(void *)&(net[net_num]),HDRSIZE-net_num);
151#ifdef EINTR
152		if ((i == -1) && (errno == EINTR)) continue;
153#endif
154		if (i <= 0) return(0);
155		net_num+=i;
156		}
157
158	/* we now have at net_num bytes in net */
159	p=net;
160	/* num=0;  */
161	n2l(p,num);
162	/* num should be rounded up to the next group of eight
163	 * we make sure that we have read a multiple of 8 bytes from the net.
164	 */
165	if ((num > MAXWRITE) || (num < 0)) /* error */
166		return(-1);
167	rnum=(num < 8)?8:((num+7)/8*8);
168
169	net_num=0;
170	while (net_num < rnum)
171		{
172		i=read(fd,(void *)&(net[net_num]),rnum-net_num);
173#ifdef EINTR
174		if ((i == -1) && (errno == EINTR)) continue;
175#endif
176		if (i <= 0) return(0);
177		net_num+=i;
178		}
179
180	/* Check if there will be data left over. */
181	if (len < num)
182		{
183		if (DES_rw_mode & DES_PCBC_MODE)
184			DES_pcbc_encrypt(net,unnet,num,sched,iv,DES_DECRYPT);
185		else
186			DES_cbc_encrypt(net,unnet,num,sched,iv,DES_DECRYPT);
187		memcpy(buf,unnet,len);
188		unnet_start=len;
189		unnet_left=num-len;
190
191		/* The following line is done because we return num
192		 * as the number of bytes read. */
193		num=len;
194		}
195	else
196		{
197		/* >output is a multiple of 8 byes, if len < rnum
198		 * >we must be careful.  The user must be aware that this
199		 * >routine will write more bytes than he asked for.
200		 * >The length of the buffer must be correct.
201		 * FIXED - Should be ok now 18-9-90 - eay */
202		if (len < rnum)
203			{
204
205			if (DES_rw_mode & DES_PCBC_MODE)
206				DES_pcbc_encrypt(net,tmpbuf,num,sched,iv,
207						 DES_DECRYPT);
208			else
209				DES_cbc_encrypt(net,tmpbuf,num,sched,iv,
210						DES_DECRYPT);
211
212			/* eay 26/08/92 fix a bug that returned more
213			 * bytes than you asked for (returned len bytes :-( */
214			memcpy(buf,tmpbuf,num);
215			}
216		else
217			{
218			if (DES_rw_mode & DES_PCBC_MODE)
219				DES_pcbc_encrypt(net,buf,num,sched,iv,
220						 DES_DECRYPT);
221			else
222				DES_cbc_encrypt(net,buf,num,sched,iv,
223						DES_DECRYPT);
224			}
225		}
226	return num;
227	}
228
229