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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: buf.c,v 1.3 2004/04/01 12:50:09 mdw Exp $ |
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4 | * |
5 | * Buffer handling |
6 | * |
7 | * (c) 2001 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Catacomb. |
13 | * |
14 | * Catacomb is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
19 | * Catacomb is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with Catacomb; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: buf.c,v $ |
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33 | * Revision 1.3 2004/04/01 12:50:09 mdw |
34 | * Add cyclic group abstraction, with test code. Separate off exponentation |
35 | * functions for better static linking. Fix a buttload of bugs on the way. |
36 | * Generally ensure that negative exponents do inversion correctly. Add |
37 | * table of standard prime-field subgroups. (Binary field subgroups are |
38 | * currently unimplemented but easy to add if anyone ever finds a good one.) |
39 | * |
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40 | * Revision 1.2 2003/11/10 22:18:30 mdw |
41 | * Build fixes. |
42 | * |
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43 | * Revision 1.1 2003/10/11 21:02:33 mdw |
44 | * Import buf stuff from tripe. |
45 | * |
46 | * Revision 1.4 2001/06/19 22:09:54 mdw |
47 | * Expose interface, for use in the proxy. |
48 | * |
49 | * Revision 1.3 2001/03/03 12:06:48 mdw |
50 | * Use 16-bit lengths on MPs, since there's a packet limit of 64K anyway. |
51 | * |
52 | * Revision 1.2 2001/02/16 21:23:20 mdw |
53 | * Various minor changes. Check that MPs are in canonical form when |
54 | * loading. |
55 | * |
56 | * Revision 1.1 2001/02/03 20:26:37 mdw |
57 | * Initial checkin. |
58 | * |
59 | */ |
60 | |
61 | /*----- Header files ------------------------------------------------------*/ |
62 | |
63 | #include <string.h> |
64 | |
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65 | #include "mp.h" |
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66 | #include "ec.h" |
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67 | #include "buf.h" |
68 | |
69 | /*----- Main code ---------------------------------------------------------*/ |
70 | |
71 | /* --- @buf_init@ --- * |
72 | * |
73 | * Arguments: @buf *b@ = pointer to a buffer block |
74 | * @void *p@ = pointer to a buffer |
75 | * @size_t sz@ = size of the buffer |
76 | * |
77 | * Returns: --- |
78 | * |
79 | * Use: Initializes the buffer block appropriately. |
80 | */ |
81 | |
82 | void buf_init(buf *b, void *p, size_t sz) |
83 | { |
84 | b->base = b->p = p; |
85 | b->limit = b->p + sz; |
86 | b->f = 0; |
87 | } |
88 | |
89 | /* --- @buf_break@ --- * |
90 | * |
91 | * Arguments: @buf *b@ = pointer to a buffer block |
92 | * |
93 | * Returns: Some negative value. |
94 | * |
95 | * Use: Marks a buffer as broken. |
96 | */ |
97 | |
98 | int buf_break(buf *b) { b->f |= BF_BROKEN; return (-1); } |
99 | |
100 | /* --- @buf_flip@ --- * |
101 | * |
102 | * Arguments: @buf *b@ = pointer to a buffer block |
103 | * |
104 | * Returns: --- |
105 | * |
106 | * Use: Flips a buffer so that if you've just been writing to it, |
107 | * you can now read from the bit you've written. |
108 | */ |
109 | |
110 | void buf_flip(buf *b) |
111 | { |
112 | b->limit = b->p; |
113 | b->p = b->base; |
114 | } |
115 | |
116 | /* --- @buf_ensure@ --- * |
117 | * |
118 | * Arguments: @buf *b@ = pointer to a buffer block |
119 | * @size_t sz@ = size of data wanted |
120 | * |
121 | * Returns: Zero if it worked, nonzero if there wasn't enough space. |
122 | * |
123 | * Use: Ensures that there are @sz@ bytes still in the buffer. |
124 | */ |
125 | |
126 | int buf_ensure(buf *b, size_t sz) { return (BENSURE(b, sz)); } |
127 | |
128 | /* --- @buf_get@ --- * |
129 | * |
130 | * Arguments: @buf *b@ = pointer to a buffer block |
131 | * @size_t sz@ = size of the buffer |
132 | * |
133 | * Returns: Pointer to the place in the buffer. |
134 | * |
135 | * Use: Reserves a space in the buffer of the requested size, and |
136 | * returns its start address. |
137 | */ |
138 | |
139 | void *buf_get(buf *b, size_t sz) |
140 | { |
141 | void *p; |
142 | if (BENSURE(b, sz)) |
143 | return (0); |
144 | p = BCUR(b); |
145 | BSTEP(b, sz); |
146 | return (p); |
147 | } |
148 | |
149 | /* --- @buf_put@ --- * |
150 | * |
151 | * Arguments: @buf *b@ = pointer to a buffer block |
152 | * @const void *p@ = pointer to a buffer |
153 | * @size_t sz@ = size of the buffer |
154 | * |
155 | * Returns: Zero if it worked, nonzero if there wasn't enough space. |
156 | * |
157 | * Use: Fetches data from some place and puts it in the buffer |
158 | */ |
159 | |
160 | int buf_put(buf *b, const void *p, size_t sz) |
161 | { |
162 | if (BENSURE(b, sz)) |
163 | return (-1); |
164 | memcpy(BCUR(b), p, sz); |
165 | BSTEP(b, sz); |
166 | return (0); |
167 | } |
168 | |
169 | /* --- @buf_getbyte@ --- * |
170 | * |
171 | * Arguments: @buf *b@ = pointer to a buffer block |
172 | * |
173 | * Returns: A byte, or less than zero if there wasn't a byte there. |
174 | * |
175 | * Use: Gets a single byte from a buffer. |
176 | */ |
177 | |
178 | int buf_getbyte(buf *b) |
179 | { |
180 | if (BENSURE(b, 1)) |
181 | return (-1); |
182 | return (*b->p++); |
183 | } |
184 | |
185 | /* --- @buf_putbyte@ --- * |
186 | * |
187 | * Arguments: @buf *b@ = pointer to a buffer block |
188 | * @int ch@ = byte to write |
189 | * |
190 | * Returns: Zero if OK, nonzero if there wasn't enough space. |
191 | * |
192 | * Use: Puts a single byte in a buffer. |
193 | */ |
194 | |
195 | int buf_putbyte(buf *b, int ch) |
196 | { |
197 | if (BENSURE(b, 1)) |
198 | return (-1); |
199 | *b->p++ = ch; |
200 | return (0); |
201 | } |
202 | |
203 | /* --- @buf_getu16@ --- * |
204 | * |
205 | * Arguments: @buf *b@ = pointer to a buffer block |
206 | * @uint16 *w@ = where to put the word |
207 | * |
208 | * Returns: Zero if OK, or nonzero if there wasn't a word there. |
209 | * |
210 | * Use: Gets a 16-bit word from a buffer. |
211 | */ |
212 | |
213 | int buf_getu16(buf *b, uint16 *w) |
214 | { |
215 | if (BENSURE(b, 2)) |
216 | return (-1); |
217 | *w = LOAD16(b->p); |
218 | BSTEP(b, 2); |
219 | return (0); |
220 | } |
221 | |
222 | /* --- @buf_putu16@ --- * |
223 | * |
224 | * Arguments: @buf *b@ = pointer to a buffer block |
225 | * @uint16 w@ = word to write |
226 | * |
227 | * Returns: Zero if OK, nonzero if there wasn't enough space. |
228 | * |
229 | * Use: Puts a 16-but word in a buffer. |
230 | */ |
231 | |
232 | int buf_putu16(buf *b, uint16 w) |
233 | { |
234 | if (BENSURE(b, 2)) |
235 | return (-1); |
236 | STORE16(b->p, w); |
237 | BSTEP(b, 2); |
238 | return (0); |
239 | } |
240 | |
241 | /* --- @buf_getu32@ --- * |
242 | * |
243 | * Arguments: @buf *b@ = pointer to a buffer block |
244 | * @uint32 *w@ = where to put the word |
245 | * |
246 | * Returns: Zero if OK, or nonzero if there wasn't a word there. |
247 | * |
248 | * Use: Gets a 32-bit word from a buffer. |
249 | */ |
250 | |
251 | int buf_getu32(buf *b, uint32 *w) |
252 | { |
253 | if (BENSURE(b, 4)) |
254 | return (-1); |
255 | *w = LOAD32(b->p); |
256 | BSTEP(b, 4); |
257 | return (0); |
258 | } |
259 | |
260 | /* --- @buf_putu32@ --- * |
261 | * |
262 | * Arguments: @buf *b@ = pointer to a buffer block |
263 | * @uint32 w@ = word to write |
264 | * |
265 | * Returns: Zero if OK, nonzero if there wasn't enough space. |
266 | * |
267 | * Use: Puts a 32-but word in a buffer. |
268 | */ |
269 | |
270 | int buf_putu32(buf *b, uint32 w) |
271 | { |
272 | if (BENSURE(b, 4)) |
273 | return (-1); |
274 | STORE32(b->p, w); |
275 | BSTEP(b, 4); |
276 | return (0); |
277 | } |
278 | |
279 | /* --- @buf_getmp@ --- * |
280 | * |
281 | * Arguments: @buf *b@ = pointer to a buffer block |
282 | * |
283 | * Returns: A multiprecision integer, or null if there wasn't one there. |
284 | * |
285 | * Use: Gets a multiprecision integer from a buffer. |
286 | */ |
287 | |
288 | mp *buf_getmp(buf *b) |
289 | { |
290 | uint16 sz; |
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291 | size_t n; |
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292 | mp *m; |
293 | if (buf_getu16(b, &sz) || buf_ensure(b, sz)) |
294 | return (0); |
295 | m = mp_loadb(MP_NEW, BCUR(b), sz); |
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296 | n = mp_octets(m); |
297 | if (n != sz && n != 0 && sz != 1) { |
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298 | mp_drop(m); |
299 | return (0); |
300 | } |
301 | BSTEP(b, sz); |
302 | return (m); |
303 | } |
304 | |
305 | /* --- @buf_putmp@ --- * |
306 | * |
307 | * Arguments: @buf *b@ = pointer to a buffer block |
308 | * @mp *m@ = a multiprecision integer |
309 | * |
310 | * Returns: Zero if it worked, nonzero if there wasn't enough space. |
311 | * |
312 | * Use: Puts a multiprecision integer to a buffer. |
313 | */ |
314 | |
315 | int buf_putmp(buf *b, mp *m) |
316 | { |
317 | size_t sz = mp_octets(m); |
318 | assert(sz < MASK16); |
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319 | if (!sz) sz = 1; |
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320 | if (buf_putu16(b, sz) || buf_ensure(b, sz)) |
321 | return (-1); |
322 | mp_storeb(m, BCUR(b), sz); |
323 | BSTEP(b, sz); |
324 | return (0); |
325 | } |
326 | |
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327 | /* --- @buf_getec@ --- * |
328 | * |
329 | * Arguments: @buf *b@ = pointer to a buffer block |
330 | * @ec *p@ = where to put the point |
331 | * |
332 | * Returns: Zero if it worked, nonzero if it failed. |
333 | * |
334 | * Use: Gets a multiprecision integer from a buffer. The point must |
335 | * be initialized. |
336 | */ |
337 | |
338 | int buf_getec(buf *b, ec *p) |
339 | { |
340 | mp *x = 0, *y = 0; |
341 | uint16 n; |
342 | if (buf_ensure(b, 2)) return (-1); |
343 | n = LOAD16(BCUR(b)); if (!n) { BSTEP(b, 2); EC_SETINF(p); return (0); } |
344 | if ((x = buf_getmp(b)) == 0 || (y = buf_getmp(b)) == 0) { |
345 | mp_drop(x); mp_drop(y); return (-1); |
346 | } |
347 | EC_DESTROY(p); p->x = x; p->y = y; p->z = 0; |
348 | return (0); |
349 | } |
350 | |
351 | /* --- @buf_putec@ --- * |
352 | * |
353 | * Arguments: @buf *b@ = pointer to a buffer block |
354 | * @ec *p@ = an elliptic curve point |
355 | * |
356 | * Returns: Zero if it worked, nonzero if there wasn't enough space. |
357 | * |
358 | * Use: Puts an elliptic curve point to a buffer. |
359 | */ |
360 | |
361 | int buf_putec(buf *b, ec *p) |
362 | { |
363 | if (EC_ATINF(p)) return (buf_putu16(b, 0)); |
364 | if (buf_putmp(b, p->x) || buf_putmp(b, p->y)) return (-1); |
365 | return (0); |
366 | } |
367 | |
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368 | /*----- That's all, folks -------------------------------------------------*/ |