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 "des_locl.h"
62
63 /* This has some uglies in it but it works - even over sockets. */
64 /*extern int errno;*/
65 int des_rw_mode=DES_PCBC_MODE;
66
67
68 /*
69 * WARNINGS:
70 *
71 * - The data format used by des_enc_write() and des_enc_read()
72 * has a cryptographic weakness: When asked to write more
73 * than MAXWRITE bytes, des_enc_write will split the data
74 * into several chunks that are all encrypted
75 * using the same IV. So don't use these functions unless you
76 * are sure you know what you do (in which case you might
77 * not want to use them anyway).
78 *
79 * - This code cannot handle non-blocking sockets.
80 *
81 * - This function uses an internal state and thus cannot be
82 * used on multiple files.
83 */
84
85
des_enc_read(int fd,void * buf,int len,des_key_schedule sched,des_cblock * iv)86 int des_enc_read(int fd, void *buf, int len, des_key_schedule sched,
87 des_cblock *iv)
88 {
89 /* data to be unencrypted */
90 int net_num=0;
91 static unsigned char *net=NULL;
92 /* extra unencrypted data
93 * for when a block of 100 comes in but is des_read one byte at
94 * a time. */
95 static unsigned char *unnet=NULL;
96 static int unnet_start=0;
97 static int unnet_left=0;
98 static unsigned char *tmpbuf=NULL;
99 int i;
100 long num=0,rnum;
101 unsigned char *p;
102
103 if (tmpbuf == NULL)
104 {
105 tmpbuf=OPENSSL_malloc(BSIZE);
106 if (tmpbuf == NULL) return(-1);
107 }
108 if (net == NULL)
109 {
110 net=OPENSSL_malloc(BSIZE);
111 if (net == NULL) return(-1);
112 }
113 if (unnet == NULL)
114 {
115 unnet=OPENSSL_malloc(BSIZE);
116 if (unnet == NULL) return(-1);
117 }
118 /* left over data from last decrypt */
119 if (unnet_left != 0)
120 {
121 if (unnet_left < len)
122 {
123 /* we still still need more data but will return
124 * with the number of bytes we have - should always
125 * check the return value */
126 memcpy(buf,&(unnet[unnet_start]),
127 unnet_left);
128 /* eay 26/08/92 I had the next 2 lines
129 * reversed :-( */
130 i=unnet_left;
131 unnet_start=unnet_left=0;
132 }
133 else
134 {
135 memcpy(buf,&(unnet[unnet_start]),len);
136 unnet_start+=len;
137 unnet_left-=len;
138 i=len;
139 }
140 return(i);
141 }
142
143 /* We need to get more data. */
144 if (len > MAXWRITE) len=MAXWRITE;
145
146 /* first - get the length */
147 while (net_num < HDRSIZE)
148 {
149 i=read(fd,(void *)&(net[net_num]),HDRSIZE-net_num);
150 #ifdef EINTR
151 if ((i == -1) && (errno == EINTR)) continue;
152 #endif
153 if (i <= 0) return(0);
154 net_num+=i;
155 }
156
157 /* we now have at net_num bytes in net */
158 p=net;
159 /* num=0; */
160 n2l(p,num);
161 /* num should be rounded up to the next group of eight
162 * we make sure that we have read a multiple of 8 bytes from the net.
163 */
164 if ((num > MAXWRITE) || (num < 0)) /* error */
165 return(-1);
166 rnum=(num < 8)?8:((num+7)/8*8);
167
168 net_num=0;
169 while (net_num < rnum)
170 {
171 i=read(fd,(void *)&(net[net_num]),rnum-net_num);
172 #ifdef EINTR
173 if ((i == -1) && (errno == EINTR)) continue;
174 #endif
175 if (i <= 0) return(0);
176 net_num+=i;
177 }
178
179 /* Check if there will be data left over. */
180 if (len < num)
181 {
182 if (des_rw_mode & DES_PCBC_MODE)
183 des_pcbc_encrypt(net,unnet,num,sched,iv,DES_DECRYPT);
184 else
185 des_cbc_encrypt(net,unnet,num,sched,iv,DES_DECRYPT);
186 memcpy(buf,unnet,len);
187 unnet_start=len;
188 unnet_left=num-len;
189
190 /* The following line is done because we return num
191 * as the number of bytes read. */
192 num=len;
193 }
194 else
195 {
196 /* >output is a multiple of 8 byes, if len < rnum
197 * >we must be careful. The user must be aware that this
198 * >routine will write more bytes than he asked for.
199 * >The length of the buffer must be correct.
200 * FIXED - Should be ok now 18-9-90 - eay */
201 if (len < rnum)
202 {
203
204 if (des_rw_mode & DES_PCBC_MODE)
205 des_pcbc_encrypt(net,tmpbuf,num,sched,iv,
206 DES_DECRYPT);
207 else
208 des_cbc_encrypt(net,tmpbuf,num,sched,iv,
209 DES_DECRYPT);
210
211 /* eay 26/08/92 fix a bug that returned more
212 * bytes than you asked for (returned len bytes :-( */
213 memcpy(buf,tmpbuf,num);
214 }
215 else
216 {
217 if (des_rw_mode & DES_PCBC_MODE)
218 des_pcbc_encrypt(net,buf,num,sched,iv,
219 DES_DECRYPT);
220 else
221 des_cbc_encrypt(net,buf,num,sched,iv,
222 DES_DECRYPT);
223 }
224 }
225 return num;
226 }
227
228