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;*/
66 OPENSSL_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
DES_enc_read(int fd,void * buf,int len,DES_key_schedule * sched,DES_cblock * iv)87 int 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