tchain.c - mixmaster - mixmaster 3.0 patched for libressl
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tchain.c (11809B)
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1 /* Mixmaster version 3.0 -- (C) 1999 - 2006 Anonymizer Inc. and others.
2
3 Mixmaster may be redistributed and modified under certain conditions.
4 This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF
5 ANY KIND, either express or implied. See the file COPYRIGHT for
6 details.
7
8 Prepare messages for remailer chain
9 $Id: chain.c 934 2006-06-24 13:40:39Z rabbi $ */
10
11
12 #include "mix3.h"
13 #include <string.h>
14 #include <ctype.h>
15 #include <assert.h>
16 #include <stdlib.h>
17
18 void clienterr(BUFFER *msgbuf, char *err)
19 {
20 if (msgbuf) {
21 buf_sets(msgbuf, "Error: ");
22 buf_appends(msgbuf, err);
23 } else
24 errlog(ERRORMSG, "%s\n", err);
25 }
26
27 void parse_badchains(int badchains[MAXREM][MAXREM], char *file, char *startindicator, REMAILER *remailer, int maxrem) {
28 int i,j;
29 FILE *list;
30 char line[LINELEN];
31
32 if (!badchains)
33 return;
34
35 for (i = 0; i < maxrem; i++ )
36 for (j = 0; j < maxrem; j++ )
37 badchains[i][j] = 0;
38 list = mix_openfile(TYPE2REL, "r");
39 if (list != NULL) {
40 while (fgets(line, sizeof(line), list) != NULL &&
41 !strleft(line, startindicator)) ;
42 while (fgets(line, sizeof(line), list) != NULL &&
43 strleft(line, "(")) {
44 char *left, *right, *tmp;
45 int lefti, righti;
46
47 left = line + 1;
48 while (*left == ' ')
49 left ++;
50
51 tmp = left + 1;
52 while (*tmp != ' ' && *tmp != '\0' && *tmp != ')')
53 tmp ++;
54 if (*tmp == '\0' || *tmp == ')')
55 /* parsing this line failed */
56 continue;
57 *tmp = '\0';
58
59 right = tmp+1;
60 while (*right == ' ')
61 right ++;
62 tmp = right + 1;
63 while (*tmp != ' ' && *tmp != '\0' && *tmp != ')')
64 tmp ++;
65 if (*tmp == '\0')
66 /* parsing this line failed */
67 continue;
68 *tmp = '\0';
69
70 lefti = -1;
71 righti = -1;
72 for (i = 1; i < maxrem; i++) {
73 if (strcmp(remailer[i].name, left) == 0)
74 lefti = i;
75 if (strcmp(remailer[i].name, right) == 0)
76 righti = i;
77 }
78 if (strcmp(left, "*") == 0)
79 lefti = 0;
80 if (strcmp(right, "*") == 0)
81 righti = 0;
82
83 if (lefti == -1 || righti == -1)
84 /* we don't know about one or both remailers */
85 continue;
86 badchains[lefti][righti] = 1;
87 }
88 fclose(list);
89 /* If some broken chain includes all remailers (*) mark it broken for
90 * every single remailer - this simplifies handling in other places */
91 for (i=1; i < maxrem; i++ ) {
92 if (badchains[0][i])
93 for (j=1; j < maxrem; j++ )
94 badchains[j][i] = 1;
95 if (badchains[i][0])
96 for (j=1; j < maxrem; j++ )
97 badchains[i][j] = 1;
98 }
99 }
100 }
101
102
103 int chain_select(int hop[], char *chainstr, int maxrem, REMAILER *remailer,
104 int type, BUFFER *feedback)
105 {
106 int len = 0;
107 int i, j, k;
108 BUFFER *chain, *selected, *addr;
109 chain = buf_new();
110 selected = buf_new();
111 addr = buf_new();
112
113 if (chainstr == NULL || chainstr[0] == '\0')
114 buf_sets(chain, CHAIN);
115 else
116 buf_sets(chain, chainstr);
117
118 /* put the chain backwards: final hop is in hop[0] */
119
120 for (i = chain->length; i >= 0; i--)
121 if (i == 0 || chain->data[i - 1] == ','
122 || chain->data[i - 1] == ';' || chain->data[i - 1] == ':') {
123 for (j = i; isspace(chain->data[j]);) /* ignore whitespace */
124 j++;
125 if (chain->data[j] == '\0')
126 break;
127
128 if (chain->data[j] == '*')
129 k = 0;
130 #if 0
131 else if (isdigit(chain->data[j]))
132 k = atoi(chain->data + j);
133 #endif /* 0 */
134 else {
135 buf_sets(selected, chain->data + j);
136 rfc822_addr(selected, addr);
137 buf_clear(selected);
138 buf_getline(addr, selected);
139 if (!selected->length)
140 buf_sets(selected, chain->data + j);
141
142 for (k = 0; k < maxrem; k++)
143 if (((remailer[k].flags.mix && type == 0) ||
144 (remailer[k].flags.cpunk && type == 1) ||
145 (remailer[k].flags.newnym && type == 2)) &&
146 (streq(remailer[k].name, selected->data) ||
147 strieq(remailer[k].addr, selected->data) ||
148 (selected->data[0] == '@' && strifind(remailer[k].addr,
149 selected->data))))
150 break;
151 }
152 if (k < 0 || k >= maxrem) {
153 if (feedback != NULL) {
154 buf_appendf(feedback, "No such remailer: %b", selected);
155 buf_nl(feedback);
156 }
157 #if 0
158 k = 0;
159 #else /* end of 0 */
160 len = -1;
161 goto end;
162 #endif /* else not 0 */
163 }
164 hop[len++] = k;
165 if (len >= 20) { /* array passed in is has length 20 */
166 if (feedback != NULL) {
167 buf_appends(feedback, "Chain too long.\n");
168 }
169 break;
170 }
171 if (i > 0)
172 chain->data[i - 1] = '\0';
173 }
174 end:
175 buf_free(chain);
176 buf_free(selected);
177 buf_free(addr);
178 return len;
179 }
180
181 int chain_randfinal(int type, REMAILER *remailer, int badchains[MAXREM][MAXREM], int maxrem, int rtype, int chain[], int chainlen, int ignore_constraints_if_necessary)
182 {
183 int randavail;
184 int i;
185 int t;
186 int select[MAXREM];
187 int secondtolasthop = (chainlen <= 1 ? -1 : chain[1]);
188 int constraints_ignored = 0;
189
190 t = rtype;
191 if (rtype == 2)
192 t = 1;
193
194 start:
195 randavail = 0;
196 /* select a random final hop */
197 for (i = 1; i < maxrem; i++) {
198 select[i] =
199 ((remailer[i].flags.mix && rtype == 0) || /* remailer supports type */
200 (remailer[i].flags.pgp && remailer[i].flags.ek && rtype == 1) ||
201 (remailer[i].flags.newnym && rtype == 2)) &&
202 (remailer[i].info[t].reliability >= 100 * RELFINAL || constraints_ignored ) && /* remailer has sufficient reliability */
203 (remailer[i].info[t].latency <= MAXLAT || constraints_ignored ) && /* remailer has low enough latency */
204 (remailer[i].info[t].latency >= MINLAT || constraints_ignored ) && /* remailer has high enough latency */
205 (type == MSG_NULL || !remailer[i].flags.middle) && /* remailer is not middleman */
206 !remailer[i].flags.star_ex && /* remailer is not excluded from random selection */
207 (remailer[i].flags.post || type != MSG_POST) && /* remailer supports post when this is a post */
208 ((secondtolasthop == -1) || !badchains[secondtolasthop][i]);
209 /* we only have hop or the previous one can send to this (may be random) */
210 randavail += select[i];
211 }
212
213 for (i = 1; i <= DISTANCE; i++)
214 if (i < chainlen && select[chain[i]] && chain[i]) {
215 select[chain[i]] = 0;
216 randavail--;
217 }
218
219 assert(randavail >= 0);
220 if (randavail == 0) {
221 if (ignore_constraints_if_necessary && !constraints_ignored) {
222 errlog(WARNING, "No reliable remailers. Ignoring for randhop\n");
223 constraints_ignored = 1;
224 goto start;
225 };
226 i = -1;
227 } else {
228 do
229 i = rnd_number(maxrem - 1) + 1;
230 while (!select[i]);
231 }
232 return (i);
233 }
234
235 int chain_rand(REMAILER *remailer, int badchains[MAXREM][MAXREM], int maxrem,
236 int thischain[], int chainlen, int t, int ignore_constraints_if_necessary)
237 /* set random chain. returns 0 if not random, 1 if random, -1 on error */
238 /* t... 0 for mixmaster Type II
239 * 1 for cypherpunk Type I
240 */
241 {
242 int hop;
243 int err = 0;
244 int constraints_ignored = 0;
245
246 assert(t == 0 || t == 1);
247
248 start:
249 for (hop = 0; hop < chainlen; hop++)
250 if (thischain[hop] == 0) {
251 int select[MAXREM];
252 int randavail = 0;
253 int i;
254
255 err = 1;
256 if (hop > 0)
257 assert(thischain[hop-1]); /* we already should have chosen a remailer after this one */
258 for (i = 1; i < maxrem; i++) {
259 select[i] = ((remailer[i].flags.mix && t == 0) || /* remailer supports type */
260 (remailer[i].flags.pgp && remailer[i].flags.ek && t == 1)) &&
261 (remailer[i].info[t].reliability >= 100 * MINREL || constraints_ignored ) && /* remailer has sufficient reliability */
262 (remailer[i].info[t].latency <= MAXLAT || constraints_ignored ) && /* remailer has low enough latency */
263 (remailer[i].info[t].latency >= MINLAT || constraints_ignored ) && /* remailer has high enough latency */
264 !remailer[i].flags.star_ex && /* remailer is not excluded from random selection */
265 !badchains[i][0] && !badchains[i][thischain[hop-1]] && /* remailer can send to the next one */
266 (hop == chainlen-1 || !badchains[thischain[hop+1]][i]);
267 /* we are at the first hop or the previous one can send to this (may be random) */
268 randavail += select[i];
269 }
270
271 for (i = hop - DISTANCE; i <= hop + DISTANCE; i++)
272 if (i >= 0 && i < chainlen && select[thischain[i]] && thischain[i]) {
273 select[thischain[i]] = 0;
274 randavail--;
275 }
276
277
278 assert(randavail >= 0);
279 if (randavail < 1) {
280 if (ignore_constraints_if_necessary && !constraints_ignored) {
281 errlog(WARNING, "No reliable remailers. Ignoring for randhop\n");
282 constraints_ignored = 1;
283 goto start;
284 };
285 err = -1;
286 goto end;
287 }
288 do
289 thischain[hop] = rnd_number(maxrem - 1) + 1;
290 while (!select[thischain[hop]]);
291 }
292 end:
293 return (err);
294 }
295
296 int mix_encrypt(int type, BUFFER *message, char *chainstr, int numcopies,
297 BUFFER *chainlist)
298 {
299 return (mix2_encrypt(type, message, chainstr, numcopies, 0, chainlist));
300 }
301
302 /* float chain_reliablity(char *chain, int chaintype,
303 char *reliability_string);
304 *
305 * Compute reliablity of a chain.
306 *
307 * We get the reliablity of the chain by multiplying the reliablity of
308 * every remailer in the chain. The return value is the reliablity of
309 * the chain, or a negative number if the reliablity can not be
310 * calculated. There are two reasons why may not be able to calculated
311 * the reliablity: A remailer in the chain is selected randomly, or we
312 * don't have statistics about one of the remailers in the chain.
313 * remailer_type indicates the remailer type:
314 * 0 = Mixmaster, 1 = Cypherpunk
315 *
316 * If reliability_string is non-NULL, the reliability is also returned
317 * as a string in this variable. The size of the string must be at
318 * least 9 characters!
319 *
320 * This function has been added by Gerd Beuster. (gb@uni-koblenz.de)
321 *--------------------------------------------------------------------*/
322
323 float chain_reliability(char *chain, int chaintype,
324 char *reliability_string){
325
326 float acc_reliability = 1; /* Accumulated reliablity */
327 char *name_start, *name_end; /* temporary pointers used
328 in string scanning */
329 char remailer_name[20]; /* The length of the array is taken from mix3.h. */
330 int error = 0;
331 int maxrem;
332 int i;
333 int previous = -1;
334 REMAILER remailer[MAXREM];
335 int badchains[MAXREM][MAXREM];
336
337 /* chaintype 0=mix 1=ek 2=newnym */
338 assert((chaintype == 0) || (chaintype == 1));
339 maxrem = (chaintype == 0 ? mix2_rlist(remailer, badchains) : t1_rlist(remailer, badchains));
340
341 /* Dissect chain */
342 name_start = chain;
343 name_end = chain;
344 while(*name_end != '\0'){ /* While string not scanned completely */
345 do /* Get next remailer */
346 name_end+=sizeof(char);
347 while( (*name_end != ',') && (*name_end != '\0'));
348 strncpy(remailer_name, name_start,
349 (name_end - name_start) / sizeof(char) + 1*sizeof(char));
350 remailer_name[name_end-name_start]='\0';
351 /* Lookup reliablity for remailer remailer_name */
352 for(i=0;
353 (i < maxrem) && (strcmp(remailer[i].name, remailer_name) != 0);
354 i++);
355 if(!strcmp(remailer[i].name, remailer_name)) { /* Found it! */
356 acc_reliability *=
357 ((float) remailer[i].info[chaintype].reliability) / 10000;
358 if (previous != -1) {
359 if (badchains[previous][i] || badchains[0][i])
360 acc_reliability = 0;
361 }
362 previous = i;
363 } else
364 error = 1; /* Did not find this remailer. We can't calculate
365 the reliablity for the whole chain. */
366 name_start = name_end+sizeof(char);
367 }
368
369 if(error || (name_start==name_end))
370 acc_reliability = -1;
371
372 /* Convert reliability into string, if appropriate */
373 if(reliability_string){
374 if(acc_reliability < 0)
375 sprintf(reliability_string, " n/a ");
376 else{
377 sprintf(reliability_string, "%6.2f", acc_reliability*100);
378 *(reliability_string+6*sizeof(char)) = '%';
379 }
380 }
381
382 return acc_reliability;
383 }
384