enc_read.c revision 296465 
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/*
66 * extern int errno;
67 */
68OPENSSL_IMPLEMENT_GLOBAL(int, DES_rw_mode) = DES_PCBC_MODE;
69
70/*-
71 * WARNINGS:
72 *
73 *  -  The data format used by DES_enc_write() and DES_enc_read()
74 *     has a cryptographic weakness: When asked to write more
75 *     than MAXWRITE bytes, DES_enc_write will split the data
76 *     into several chunks that are all encrypted
77 *     using the same IV.  So don't use these functions unless you
78 *     are sure you know what you do (in which case you might
79 *     not want to use them anyway).
80 *
81 *  -  This code cannot handle non-blocking sockets.
82 *
83 *  -  This function uses an internal state and thus cannot be
84 *     used on multiple files.
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    /*
94     * extra unencrypted data for when a block of 100 comes in but is
95     * des_read one byte at a time.
96     */
97    static unsigned char *unnet = NULL;
98    static int unnet_start = 0;
99    static int unnet_left = 0;
100    static unsigned char *tmpbuf = NULL;
101    int i;
102    long num = 0, rnum;
103    unsigned char *p;
104
105    if (tmpbuf == NULL) {
106        tmpbuf = OPENSSL_malloc(BSIZE);
107        if (tmpbuf == NULL)
108            return (-1);
109    }
110    if (net == NULL) {
111        net = OPENSSL_malloc(BSIZE);
112        if (net == NULL)
113            return (-1);
114    }
115    if (unnet == NULL) {
116        unnet = OPENSSL_malloc(BSIZE);
117        if (unnet == NULL)
118            return (-1);
119    }
120    /* left over data from last decrypt */
121    if (unnet_left != 0) {
122        if (unnet_left < len) {
123            /*
124             * we still still need more data but will return with the number
125             * of bytes we have - should always check the return value
126             */
127            memcpy(buf, &(unnet[unnet_start]), unnet_left);
128            /*
129             * eay 26/08/92 I had the next 2 lines reversed :-(
130             */
131            i = unnet_left;
132            unnet_start = unnet_left = 0;
133        } else {
134            memcpy(buf, &(unnet[unnet_start]), len);
135            unnet_start += len;
136            unnet_left -= len;
137            i = len;
138        }
139        return (i);
140    }
141
142    /* We need to get more data. */
143    if (len > MAXWRITE)
144        len = MAXWRITE;
145
146    /* first - get the length */
147    while (net_num < HDRSIZE) {
148#ifndef _WIN32
149        i = read(fd, (void *)&(net[net_num]), HDRSIZE - net_num);
150#else
151        i = _read(fd, (void *)&(net[net_num]), HDRSIZE - net_num);
152#endif
153#ifdef EINTR
154        if ((i == -1) && (errno == EINTR))
155            continue;
156#endif
157        if (i <= 0)
158            return (0);
159        net_num += i;
160    }
161
162    /* we now have at net_num bytes in net */
163    p = net;
164    /* num=0;  */
165    n2l(p, num);
166    /*
167     * num should be rounded up to the next group of eight we make sure that
168     * we have read a multiple of 8 bytes from the net.
169     */
170    if ((num > MAXWRITE) || (num < 0)) /* error */
171        return (-1);
172    rnum = (num < 8) ? 8 : ((num + 7) / 8 * 8);
173
174    net_num = 0;
175    while (net_num < rnum) {
176        i = read(fd, (void *)&(net[net_num]), rnum - net_num);
177#ifdef EINTR
178        if ((i == -1) && (errno == EINTR))
179            continue;
180#endif
181        if (i <= 0)
182            return (0);
183        net_num += i;
184    }
185
186    /* Check if there will be data left over. */
187    if (len < num) {
188        if (DES_rw_mode & DES_PCBC_MODE)
189            DES_pcbc_encrypt(net, unnet, num, sched, iv, DES_DECRYPT);
190        else
191            DES_cbc_encrypt(net, unnet, num, sched, iv, DES_DECRYPT);
192        memcpy(buf, unnet, len);
193        unnet_start = len;
194        unnet_left = num - len;
195
196        /*
197         * The following line is done because we return num as the number of
198         * bytes read.
199         */
200        num = len;
201    } else {
202        /*-
203         * >output is a multiple of 8 byes, if len < rnum
204         * >we must be careful.  The user must be aware that this
205         * >routine will write more bytes than he asked for.
206         * >The length of the buffer must be correct.
207         * FIXED - Should be ok now 18-9-90 - eay */
208        if (len < rnum) {
209
210            if (DES_rw_mode & DES_PCBC_MODE)
211                DES_pcbc_encrypt(net, tmpbuf, num, sched, iv, DES_DECRYPT);
212            else
213                DES_cbc_encrypt(net, tmpbuf, num, sched, iv, DES_DECRYPT);
214
215            /*
216             * eay 26/08/92 fix a bug that returned more bytes than you asked
217             * for (returned len bytes :-(
218             */
219            memcpy(buf, tmpbuf, num);
220        } else {
221            if (DES_rw_mode & DES_PCBC_MODE)
222                DES_pcbc_encrypt(net, buf, num, sched, iv, DES_DECRYPT);
223            else
224                DES_cbc_encrypt(net, buf, num, sched, iv, DES_DECRYPT);
225        }
226    }
227    return num;
228}
229