1 /* ----------------------------------------------------------------------------
2 * checksum.c --- Checksum generator functions
3 * nca-073-9
4 *
5 * Copyright (c) 1996-2000 by Netcetera AG.
6 * Copyright (c) 2001 by Apache Software Foundation.
7 * All rights reserved.
8 *
9 * See the file "license.terms" for information on usage and
10 * redistribution of this file, and for a DISCLAIMER OF ALL WARRANTIES.
11 *
12 * @(#) $Id: checksum.c 814683 2009-09-14 15:11:40Z ronnie $
13 * ------------------------------------------------------------------------- */
14 #include <tcl.h>
15 #include "checksum.h"
16
17 unsigned short crc_lut[256] = {
18 0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
19 0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
20 0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
21 0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
22 0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
23 0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
24 0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
25 0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
26 0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
27 0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
28 0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
29 0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
30 0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
31 0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
32 0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
33 0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
34 0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
35 0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
36 0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
37 0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
38 0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
39 0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
40 0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
41 0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
42 0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
43 0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
44 0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
45 0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
46 0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
47 0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
48 0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
49 0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
50 };
51
52 /* ----------------------------------------------------------------------------
53 * crcCalc -- from Tcl_Obj, calculate CRC
54 * ------------------------------------------------------------------------- */
crcCalc(Tcl_Obj * in)55 unsigned short crcCalc(Tcl_Obj * in)
56 {
57
58 unsigned char *bytes = NULL;
59 int bytesLen = -1;
60 unsigned short word = 0;
61 int i = 0;
62 volatile unsigned char idx = 0;
63
64 if (in == NULL)
65 return 0;
66
67 bytes = Tcl_GetByteArrayFromObj(in, &bytesLen);
68 word = (1 | (1 << 8));
69
70 for (i = 0; i < bytesLen; i++) {
71 idx = (unsigned char) (bytes[i] ^ WEB_HIG_BYTE(word));
72 word = (crc_lut[idx]) ^ (WEB_LOW_BYTE(word) << 8);
73 }
74
75 return word;
76 }
77
78 /* ----------------------------------------------------------------------------
79 * crcAsciify -- generate ASCII rep of 2 bytes
80 * ------------------------------------------------------------------------- */
crcAsciify(unsigned short crc)81 Tcl_Obj *crcAsciify(unsigned short crc)
82 {
83
84 Tcl_Obj *tmp = NULL;
85 char tmpc1 = 0;
86 char tmpc2 = 0;
87 unsigned char byte = 0;
88
89 tmp = Tcl_NewObj();
90 Tcl_IncrRefCount(tmp);
91
92 byte = WEB_HIG_BYTE(crc);
93
94 tmpc1 = (byte / 16) + 'A';
95 tmpc2 = (byte % 16) + 'A';
96
97 Tcl_AppendToObj(tmp, &tmpc1, 1);
98 Tcl_AppendToObj(tmp, &tmpc2, 1);
99
100 byte = WEB_LOW_BYTE(crc);
101
102 tmpc1 = (byte / 16) + 'A';
103 tmpc2 = (byte % 16) + 'A';
104
105 Tcl_AppendToObj(tmp, &tmpc1, 1);
106 Tcl_AppendToObj(tmp, &tmpc2, 1);
107
108 return tmp;
109 }
110
111 /* ----------------------------------------------------------------------------
112 * crcDeAsciify -- from ASII rep back to 2 bytes
113 * ------------------------------------------------------------------------- */
crcDeAsciify(Tcl_Obj * in)114 unsigned short crcDeAsciify(Tcl_Obj * in)
115 {
116
117 unsigned char lowByte = 0;
118 unsigned char higByte = 0;
119 char *str = NULL;
120 int len = 0;
121 unsigned short crc = 0;
122
123 if (in == NULL)
124 return 0;
125
126 str = Tcl_GetStringFromObj(in, &len);
127
128 if (len != 4)
129 return 0;
130
131 higByte = ((str[0] - 'A') << 4) | ((str[1] - 'A'));
132 lowByte = ((str[2] - 'A') << 4) | ((str[3] - 'A'));
133
134 crc = (higByte << 8) | lowByte;
135
136 return crc;
137 }
138
139 /* ----------------------------------------------------------------------------
140 * crcCheck -- check if crc at end of string is valid for string
141 * ------------------------------------------------------------------------- */
crcCheck(Tcl_Obj * in)142 Tcl_Obj *crcCheck(Tcl_Obj * in)
143 {
144
145 Tcl_Obj *crcObj = NULL;
146 int len;
147 int crc1;
148 int crc2;
149
150 if (in == NULL)
151 return NULL;
152
153 len = Tcl_GetCharLength(in);
154
155 if (len < 4)
156 return NULL;
157
158 crcObj = Tcl_GetRange(in, len - 4, len - 1);
159 Tcl_IncrRefCount(crcObj);
160
161 crc1 = crcDeAsciify(crcObj);
162
163 Tcl_DecrRefCount(crcObj);
164
165 crcObj = Tcl_GetRange(in, 0, len - 5);
166 Tcl_IncrRefCount(crcObj);
167
168 crc2 = crcCalc(crcObj);
169
170 if (crc2 == crc1) {
171
172 return crcObj;
173 }
174
175 Tcl_DecrRefCount(crcObj);
176
177 return NULL;
178 }
179
180 /* ----------------------------------------------------------------------------
181 * crcAdd -- append crc to string
182 * ------------------------------------------------------------------------- */
crcAdd(Tcl_Obj * in)183 int crcAdd(Tcl_Obj * in)
184 {
185
186 unsigned short crc = 0;
187 Tcl_Obj *tmp2 = NULL;
188
189 if (in == NULL)
190 return TCL_ERROR;
191
192 crc = crcCalc(in);
193 tmp2 = crcAsciify(crc);
194
195 if (tmp2 == NULL)
196 return TCL_ERROR;
197
198 Tcl_AppendObjToObj(in, tmp2);
199
200 Tcl_DecrRefCount(tmp2);
201
202 return TCL_OK;
203 }
204