Mix/Src/chain.c

/* Mixmaster version 3  --  (C) 1999 Anonymizer Inc.

   Mixmaster may be redistributed and modified under certain conditions.
   This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF
   ANY KIND, either express or implied. See the file COPYRIGHT for
   details.

   Prepare messages for remailer chain
   $Id: chain.c,v 1.6 2003/04/02 13:14:13 weaselp Exp $ */


#include "mix3.h"
#include <string.h>
#include <ctype.h>
#include <assert.h>
#include <stdlib.h>

void clienterr(BUFFER *msgbuf, char *err)
{
  if (msgbuf) {
    buf_sets(msgbuf, "Error: ");
    buf_appends(msgbuf, err);
  } else
    errlog(ERRORMSG, "%s\n", err);
}

int chain_select(int hop[], char *chainstr, int maxrem, REMAILER *remailer,
                 int type, BUFFER *feedback)
{
  int len = 0;
  int i, j, k;
  BUFFER *chain, *selected, *addr;
  chain = buf_new();
  selected = buf_new();
  addr = buf_new();

  if (chainstr == NULL || chainstr[0] == '\0')
    buf_sets(chain, CHAIN);
  else
    buf_sets(chain, chainstr);

  /* put the chain backwards: final hop is in hop[0] */

  for (i = chain->length; i >= 0; i--)
    if (i == 0 || chain->data[i - 1] <= ' ' || chain->data[i - 1] == ','
        || chain->data[i - 1] == ';' || chain->data[i - 1] == ':') {
      for (j = i; isspace(chain->data[j]);)     /* ignore whitespace */
        j++;
      if (chain->data[j] == '\0')
        break;

      if (chain->data[j] == '*')
        k = 0;
#if 0
      else if (isdigit(chain->data[j]))
        k = atoi(chain->data + j);
#endif /* 0 */
      else {
        buf_sets(selected, chain->data + j);
        rfc822_addr(selected, addr);
        buf_clear(selected);
        buf_getline(addr, selected);
        if (!selected->length)
          buf_sets(selected, chain->data + j);

        for (k = 0; k < maxrem; k++)
          if (((remailer[k].flags.mix && type == 0) ||
               (remailer[k].flags.cpunk && type == 1) ||
               (remailer[k].flags.newnym && type == 2)) &&
              (streq(remailer[k].name, selected->data) ||
               strieq(remailer[k].addr, selected->data) ||
               (selected->data[0] == '@' && strifind(remailer[k].addr,
                                            selected->data))))
            break;
      }
      if (k < 0 || k >= maxrem) {
        if (feedback != NULL) {
                buf_appendf(feedback, "No such remailer: %b", selected);
                buf_nl(feedback);
        }
#if 0
        k = 0;
#else /* end of 0 */
        len = -1;
        goto end;
#endif /* else not 0 */
      }
      hop[len++] = k;
      if (len >= 20) {          /* array passed in is has length 20 */
        if (feedback != NULL) {
                buf_appends(feedback, "Chain too long.\n");
        }
        break;
      }
      if (i > 0)
        chain->data[i - 1] = '\0';
    }
end:
  buf_free(chain);
  buf_free(selected);
  buf_free(addr);
  return len;
}

int chain_randfinal(int type, REMAILER *remailer, int maxrem, int rtype)
{
  int num = 0;
  int i;
  int t;

  t = rtype;
  if (rtype == 2)
    t = 1;

  /* select a random final hop */
  for (i = 1; i < maxrem; i++) {
    if (((remailer[i].flags.mix && rtype == 0) ||
         (remailer[i].flags.pgp && remailer[i].flags.ek && rtype == 1) ||
         (remailer[i].flags.newnym && rtype == 2)) &&
        remailer[i].info[t].reliability >= 100 * RELFINAL &&
        remailer[i].info[t].latency <= MAXLAT &&
        (type == MSG_NULL || !remailer[i].flags.middle) &&
        !remailer[i].flags.star_ex &&
        (remailer[i].flags.post || type != MSG_POST))
      num++;
  }
  if (num == 0)
    i = -1;
  else {
    do
      i = rnd_number(maxrem) + 1;
    while (!(((remailer[i].flags.mix && rtype == 0) ||
              (remailer[i].flags.pgp && remailer[i].flags.ek && rtype == 1) ||
              (remailer[i].flags.newnym && rtype == 2)) &&
             remailer[i].info[t].reliability >= 100 * RELFINAL &&
             remailer[i].info[t].latency <= MAXLAT &&
             (type == MSG_NULL || !remailer[i].flags.middle) &&
             !remailer[i].flags.star_ex &&
             (remailer[i].flags.post || type != MSG_POST)));
  }
  return (i);
}

int chain_rand(REMAILER *remailer, int maxrem,
               int thischain[], int chainlen, int t)
     /* set random chain. returns 0 if not random, 1 if random, -1 on error */
{
  int hop;
  int err = 0;

  assert(t == 0 || t == 1);

  for (hop = 0; hop < chainlen; hop++)
    if (thischain[hop] == 0) {
      int select[MAXREM];
      int randavail = 0;
      int i;

      err = 1;
      for (i = 1; i < maxrem; i++)
        select[i] = ((remailer[i].flags.mix && t == 0) ||
                     (remailer[i].flags.pgp && remailer[i].flags.ek && t == 1))
          && remailer[i].info[t].reliability >= 100 * MINREL &&
          !remailer[i].flags.star_ex &&
          remailer[i].info[t].latency <= MAXLAT,
          randavail += select[i];

      for (i = hop - DISTANCE; i <= hop + DISTANCE; i++)
        if (i >= 0 && i < chainlen && select[thischain[i]])
          select[thischain[i]] = 0, randavail--;

      if (randavail < 1) {
        err = -1;
        goto end;
      }
      do
        thischain[hop] = rnd_number(maxrem - 1) + 1;
      while (!select[thischain[hop]]);
    }
end:
  return (err);
}

int mix_encrypt(int type, BUFFER *message, char *chainstr, int numcopies,
                BUFFER *chainlist)
{
  return (mix2_encrypt(type, message, chainstr, numcopies, chainlist));
}

/* float chain_reliablity(char *chain, int chaintype,
                          char *reliability_string);
 *
 * Compute reliablity of a chain.
 *
 * We get the reliablity of the chain by multiplying the reliablity of
 * every remailer in the chain. The return value is the reliablity of
 * the chain, or a negative number if the reliablity can not be
 * calculated. There are two reasons why may not be able to calculated
 * the reliablity: A remailer in the chain is selected randomly, or we
 * don't have statistics about one of the remailers in the chain.
 * remailer_type indicates the remailer type:
 * 0 = Mixmaster, 1 = Cypherpunk
 *
 * If reliability_string is non-NULL, the reliability is also returned
 * as a string in this variable. The size of the string must be at
 * least 9 characters!
 *
 * This function has been added by Gerd Beuster. (gb@uni-koblenz.de)
 *--------------------------------------------------------------------*/

float chain_reliability(char *chain, int chaintype,
                        char *reliability_string){

  float acc_reliability = 1; /* Accumulated reliablity */
  char *name_start, *name_end; /* temporary pointers used
                                 in string scanning */
  char remailer_name[20]; /* The length of the array is taken from mix3.h. */
  int error = 0;
  int maxrem;
  int i;
  REMAILER remailer[MAXREM];

  /* chaintype 0=mix 1=ek 2=newnym */
  assert((chaintype == 0) || (chaintype == 1));
  maxrem = (chaintype == 0 ? mix2_rlist(remailer) : t1_rlist(remailer));

  /* Dissect chain */
  name_start = chain;
  name_end = chain;
  while(*name_end != '\0'){ /* While string not scanned completely */
    do /* Get next remailer */
      name_end+=sizeof(char);
    while( (*name_end != ',') && (*name_end != '\0'));
    strncpy(remailer_name, name_start,
            (name_end - name_start) / sizeof(char) + 1*sizeof(char));
    remailer_name[name_end-name_start]='\0';
    /* Lookup reliablity for remailer remailer_name */
    for(i=0;
        (i < maxrem) && (strcmp(remailer[i].name, remailer_name) != 0);
        i++);
    if(!strcmp(remailer[i].name, remailer_name)) /* Found it! */
      acc_reliability *=
        ((float) remailer[i].info[chaintype].reliability) / 10000;
    else
      error = 1; /* Did not find this remailer. We can't calculate
                    the reliablity for the whole chain. */
    name_start = name_end+sizeof(char);
  }

  if(error || (name_start==name_end))
    acc_reliability = -1;

  /* Convert reliability into string, if appropriate */
  if(reliability_string){
    if(acc_reliability < 0)
      sprintf(reliability_string, "  n/a  ");
    else{
      sprintf(reliability_string, "%6.2f", acc_reliability*100);
      *(reliability_string+6*sizeof(char)) = '%';
    }
  }

  return acc_reliability;
}

1	rabbi	1	/* Mixmaster version 3 -- (C) 1999 Anonymizer Inc.
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	weaselp	493	$Id: chain.c,v 1.6 2003/04/02 13:14:13 weaselp Exp $ */
10	rabbi	1
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			int chain_select(int hop[], char chainstr, int maxrem, REMAILER remailer,
28			int type, BUFFER *feedback)
29			{
30			int len = 0;
31			int i, j, k;
32			BUFFER chain, selected, *addr;
33			chain = buf_new();
34			selected = buf_new();
35			addr = buf_new();
36
37			if (chainstr == NULL \|\| chainstr[0] == '\0')
38			buf_sets(chain, CHAIN);
39			else
40			buf_sets(chain, chainstr);
41
42			/* put the chain backwards: final hop is in hop[0] */
43
44			for (i = chain->length; i >= 0; i--)
45			if (i == 0 \|\| chain->data[i - 1] <= ' ' \|\| chain->data[i - 1] == ','
46			\|\| chain->data[i - 1] == ';' \|\| chain->data[i - 1] == ':') {
47			for (j = i; isspace(chain->data[j]);) /* ignore whitespace */
48			j++;
49			if (chain->data[j] == '\0')
50			break;
51
52			if (chain->data[j] == '*')
53			k = 0;
54	weaselp	332	#if 0
55	rabbi	1	else if (isdigit(chain->data[j]))
56			k = atoi(chain->data + j);
57	rabbi	262	#endif /* 0 */
58	rabbi	1	else {
59			buf_sets(selected, chain->data + j);
60			rfc822_addr(selected, addr);
61			buf_clear(selected);
62			buf_getline(addr, selected);
63			if (!selected->length)
64			buf_sets(selected, chain->data + j);
65
66			for (k = 0; k < maxrem; k++)
67			if (((remailer[k].flags.mix && type == 0) \|\|
68			(remailer[k].flags.cpunk && type == 1) \|\|
69			(remailer[k].flags.newnym && type == 2)) &&
70			(streq(remailer[k].name, selected->data) \|\|
71			strieq(remailer[k].addr, selected->data) \|\|
72			(selected->data[0] == '@' && strifind(remailer[k].addr,
73			selected->data))))
74			break;
75			}
76			if (k < 0 \|\| k >= maxrem) {
77	weaselp	493	if (feedback != NULL) {
78			buf_appendf(feedback, "No such remailer: %b", selected);
79			buf_nl(feedback);
80			}
81	weaselp	332	#if 0
82	rabbi	1	k = 0;
83	rabbi	262	#else /* end of 0 */
84	rabbi	1	len = -1;
85			goto end;
86	rabbi	262	#endif /* else not 0 */
87	rabbi	1	}
88			hop[len++] = k;
89	rabbi	26	if (len >= 20) { /* array passed in is has length 20 */
90	weaselp	493	if (feedback != NULL) {
91			buf_appends(feedback, "Chain too long.\n");
92			}
93	rabbi	1	break;
94			}
95			if (i > 0)
96			chain->data[i - 1] = '\0';
97			}
98			end:
99			buf_free(chain);
100			buf_free(selected);
101			buf_free(addr);
102			return len;
103			}
104
105			int chain_randfinal(int type, REMAILER *remailer, int maxrem, int rtype)
106			{
107			int num = 0;
108			int i;
109			int t;
110
111			t = rtype;
112			if (rtype == 2)
113			t = 1;
114
115			/* select a random final hop */
116			for (i = 1; i < maxrem; i++) {
117			if (((remailer[i].flags.mix && rtype == 0) \|\|
118			(remailer[i].flags.pgp && remailer[i].flags.ek && rtype == 1) \|\|
119			(remailer[i].flags.newnym && rtype == 2)) &&
120			remailer[i].info[t].reliability >= 100 * RELFINAL &&
121			remailer[i].info[t].latency <= MAXLAT &&
122			(type == MSG_NULL \|\| !remailer[i].flags.middle) &&
123	weaselp	387	!remailer[i].flags.star_ex &&
124	rabbi	1	(remailer[i].flags.post \|\| type != MSG_POST))
125			num++;
126			}
127			if (num == 0)
128			i = -1;
129			else {
130			do
131			i = rnd_number(maxrem) + 1;
132			while (!(((remailer[i].flags.mix && rtype == 0) \|\|
133			(remailer[i].flags.pgp && remailer[i].flags.ek && rtype == 1) \|\|
134			(remailer[i].flags.newnym && rtype == 2)) &&
135			remailer[i].info[t].reliability >= 100 * RELFINAL &&
136			remailer[i].info[t].latency <= MAXLAT &&
137			(type == MSG_NULL \|\| !remailer[i].flags.middle) &&
138	weaselp	387	!remailer[i].flags.star_ex &&
139	rabbi	1	(remailer[i].flags.post \|\| type != MSG_POST)));
140			}
141			return (i);
142			}
143
144			int chain_rand(REMAILER *remailer, int maxrem,
145			int thischain[], int chainlen, int t)
146			/* set random chain. returns 0 if not random, 1 if random, -1 on error */
147			{
148			int hop;
149			int err = 0;
150
151			assert(t == 0 \|\| t == 1);
152
153			for (hop = 0; hop < chainlen; hop++)
154			if (thischain[hop] == 0) {
155			int select[MAXREM];
156			int randavail = 0;
157			int i;
158
159			err = 1;
160			for (i = 1; i < maxrem; i++)
161			select[i] = ((remailer[i].flags.mix && t == 0) \|\|
162			(remailer[i].flags.pgp && remailer[i].flags.ek && t == 1))
163			&& remailer[i].info[t].reliability >= 100 * MINREL &&
164	weaselp	387	!remailer[i].flags.star_ex &&
165	rabbi	1	remailer[i].info[t].latency <= MAXLAT,
166			randavail += select[i];
167
168			for (i = hop - DISTANCE; i <= hop + DISTANCE; i++)
169			if (i >= 0 && i < chainlen && select[thischain[i]])
170			select[thischain[i]] = 0, randavail--;
171
172			if (randavail < 1) {
173			err = -1;
174			goto end;
175			}
176			do
177			thischain[hop] = rnd_number(maxrem - 1) + 1;
178			while (!select[thischain[hop]]);
179			}
180			end:
181			return (err);
182			}
183
184			int mix_encrypt(int type, BUFFER message, char chainstr, int numcopies,
185			BUFFER *chainlist)
186			{
187			return (mix2_encrypt(type, message, chainstr, numcopies, chainlist));
188			}
189
190			/* float chain_reliablity(char *chain, int chaintype,
191	weaselp	332	char *reliability_string);
192	rabbi	1	*
193			* Compute reliablity of a chain.
194			*
195			* We get the reliablity of the chain by multiplying the reliablity of
196			* every remailer in the chain. The return value is the reliablity of
197			* the chain, or a negative number if the reliablity can not be
198			* calculated. There are two reasons why may not be able to calculated
199			* the reliablity: A remailer in the chain is selected randomly, or we
200			* don't have statistics about one of the remailers in the chain.
201			* remailer_type indicates the remailer type:
202			* 0 = Mixmaster, 1 = Cypherpunk
203			*
204			* If reliability_string is non-NULL, the reliability is also returned
205			* as a string in this variable. The size of the string must be at
206			* least 9 characters!
207			*
208			* This function has been added by Gerd Beuster. (gb@uni-koblenz.de)
209			--------------------------------------------------------------------/
210
211			float chain_reliability(char *chain, int chaintype,
212			char *reliability_string){
213	weaselp	332
214	rabbi	1	float acc_reliability = 1; /* Accumulated reliablity */
215			char name_start, name_end; /* temporary pointers used
216			in string scanning */
217			char remailer_name[20]; /* The length of the array is taken from mix3.h. */
218			int error = 0;
219			int maxrem;
220			int i;
221			REMAILER remailer[MAXREM];
222
223			/* chaintype 0=mix 1=ek 2=newnym */
224			assert((chaintype == 0) \|\| (chaintype == 1));
225			maxrem = (chaintype == 0 ? mix2_rlist(remailer) : t1_rlist(remailer));
226
227			/* Dissect chain */
228			name_start = chain;
229			name_end = chain;
230			while(name_end != '\0'){ / While string not scanned completely */
231			do /* Get next remailer */
232			name_end+=sizeof(char);
233			while( (name_end != ',') && (name_end != '\0'));
234			strncpy(remailer_name, name_start,
235			(name_end - name_start) / sizeof(char) + 1*sizeof(char));
236			remailer_name[name_end-name_start]='\0';
237			/* Lookup reliablity for remailer remailer_name */
238			for(i=0;
239			(i < maxrem) && (strcmp(remailer[i].name, remailer_name) != 0);
240			i++);
241			if(!strcmp(remailer[i].name, remailer_name)) /* Found it! */
242			acc_reliability *=
243			((float) remailer[i].info[chaintype].reliability) / 10000;
244			else
245			error = 1; /* Did not find this remailer. We can't calculate
246			the reliablity for the whole chain. */
247			name_start = name_end+sizeof(char);
248			}
249
250			if(error \|\| (name_start==name_end))
251			acc_reliability = -1;
252
253			/* Convert reliability into string, if appropriate */
254			if(reliability_string){
255			if(acc_reliability < 0)
256			sprintf(reliability_string, " n/a ");
257			else{
258			sprintf(reliability_string, "%6.2f", acc_reliability*100);
259			(reliability_string+6sizeof(char)) = '%';
260			}
261			}
262	weaselp	332
263	rabbi	1	return acc_reliability;
264			}
265	weaselp	332