1 /* $NetBSD: cnmagic.c,v 1.14 2017/05/04 11:01:16 kamil Exp $ */
2
3 /*
4 * Copyright (c) 2000 Eduardo Horvath
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28 #include <sys/cdefs.h>
29 __KERNEL_RCSID(0, "$NetBSD: cnmagic.c,v 1.14 2017/05/04 11:01:16 kamil Exp $");
30
31 #include <sys/param.h>
32 #include <sys/systm.h>
33 #include <sys/kernel.h>
34
35 #define ENCODE_STATE(c, n) (short)(((c)&0x1ff)|(((n)&0x7f)<<9))
36
37 static unsigned short cn_magic[CNS_LEN];
38
39 /*
40 * Initialize a cnm_state_t.
41 */
42 void
cn_init_magic(cnm_state_t * cnm)43 cn_init_magic(cnm_state_t *cnm)
44 {
45 cnm->cnm_state = 0;
46 cnm->cnm_magic = cn_magic;
47 }
48
49 /*
50 * Destroy a cnm_state_t.
51 */
52 void
cn_destroy_magic(cnm_state_t * cnm)53 cn_destroy_magic(cnm_state_t *cnm)
54 {
55 cnm->cnm_state = 0;
56 cnm->cnm_magic = NULL;
57 }
58
59 /*
60 * Translate a magic string to a state
61 * machine table.
62 */
63 int
cn_set_magic(const char * smagic)64 cn_set_magic(const char *smagic)
65 {
66 const unsigned char *magic = (const unsigned char *)smagic;
67 unsigned short i, c, n;
68 unsigned short m[CNS_LEN];
69
70 for (i = 0; i < CNS_LEN; i++) {
71 c = *magic++;
72 switch (c) {
73 case 0:
74 /* End of string */
75 if (i == 0) {
76 /* empty string? */
77 #ifdef DEBUG
78 printf("cn_set_magic(): empty!\n");
79 #endif
80 }
81 cn_magic[i] = 0;
82 while (i--)
83 cn_magic[i] = m[i];
84 return 0;
85 case 0x27:
86 /* Escape sequence */
87 c = *magic++;
88 switch (c) {
89 case 0x27:
90 break;
91 case 0x01:
92 /* BREAK */
93 c = CNC_BREAK;
94 break;
95 case 0x02:
96 /* NUL */
97 c = 0;
98 break;
99 }
100 /* FALLTHROUGH */
101 default:
102 /* Transition to the next state. */
103 n = *magic ? i + 1 : CNS_TERM;
104 #ifdef DEBUG
105 if (!cold)
106 aprint_normal("mag %d %x:%x\n", i, c, n);
107 #endif
108 m[i] = ENCODE_STATE(c, n);
109 break;
110 }
111 }
112 return EINVAL;
113 }
114
115 /*
116 * Translate a state machine table back to
117 * a magic string.
118 */
119 int
cn_get_magic(char * magic,size_t maglen)120 cn_get_magic(char *magic, size_t maglen)
121 {
122 size_t i, n = 0;
123
124 #define ADD_CHAR(x) \
125 do \
126 if (n < maglen) \
127 magic[n++] = (x); \
128 else \
129 goto error; \
130 while (/*CONSTCOND*/0)
131
132 for (i = 0; i < CNS_LEN; /* empty */) {
133 unsigned short c = cn_magic[i];
134 i = CNS_MAGIC_NEXT(c);
135 if (i == 0)
136 goto finish;
137
138 /* Translate a character */
139 switch (CNS_MAGIC_VAL(c)) {
140 case CNC_BREAK:
141 ADD_CHAR(0x27);
142 ADD_CHAR(0x01);
143 break;
144 case 0:
145 ADD_CHAR(0x27);
146 ADD_CHAR(0x02);
147 break;
148 case 0x27:
149 ADD_CHAR(0x27);
150 ADD_CHAR(0x27);
151 break;
152 default:
153 ADD_CHAR(c);
154 break;
155 }
156 /* Now go to the next state */
157 if (i == CNS_TERM)
158 goto finish;
159 }
160
161 error:
162 return EINVAL;
163
164 finish:
165 /* Either termination state or empty machine */
166 ADD_CHAR('\0');
167 return 0;
168 }
169