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 1.3 2002/09/18 23:26:16 rabbi 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) {
        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 */
        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.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.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].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	rabbi	262	$Id: chain.c,v 1.3 2002/09/18 23:26:16 rabbi 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	rabbi	262	#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			buf_appendf(feedback, "No such remailer: %b", selected);
78			buf_nl(feedback);
79	rabbi	262	#if 0
80	rabbi	1	k = 0;
81	rabbi	262	#else /* end of 0 */
82	rabbi	1	len = -1;
83			goto end;
84	rabbi	262	#endif /* else not 0 */
85	rabbi	1	}
86			hop[len++] = k;
87	rabbi	26	if (len >= 20) { /* array passed in is has length 20 */
88	rabbi	1	buf_appends(feedback, "Chain too long.\n");
89			break;
90			}
91			if (i > 0)
92			chain->data[i - 1] = '\0';
93			}
94			end:
95			buf_free(chain);
96			buf_free(selected);
97			buf_free(addr);
98			return len;
99			}
100
101			int chain_randfinal(int type, REMAILER *remailer, int maxrem, int rtype)
102			{
103			int num = 0;
104			int i;
105			int t;
106
107			t = rtype;
108			if (rtype == 2)
109			t = 1;
110
111			/* select a random final hop */
112			for (i = 1; i < maxrem; i++) {
113			if (((remailer[i].flags.mix && rtype == 0) \|\|
114			(remailer[i].flags.pgp && remailer[i].flags.ek && rtype == 1) \|\|
115			(remailer[i].flags.newnym && rtype == 2)) &&
116			remailer[i].info[t].reliability >= 100 * RELFINAL &&
117			remailer[i].info[t].latency <= MAXLAT &&
118			(type == MSG_NULL \|\| !remailer[i].flags.middle) &&
119			(remailer[i].flags.post \|\| type != MSG_POST))
120			num++;
121			}
122			if (num == 0)
123			i = -1;
124			else {
125			do
126			i = rnd_number(maxrem) + 1;
127			while (!(((remailer[i].flags.mix && rtype == 0) \|\|
128			(remailer[i].flags.pgp && remailer[i].flags.ek && rtype == 1) \|\|
129			(remailer[i].flags.newnym && rtype == 2)) &&
130			remailer[i].info[t].reliability >= 100 * RELFINAL &&
131			remailer[i].info[t].latency <= MAXLAT &&
132			(type == MSG_NULL \|\| !remailer[i].flags.middle) &&
133			(remailer[i].flags.post \|\| type != MSG_POST)));
134			}
135			return (i);
136			}
137
138			int chain_rand(REMAILER *remailer, int maxrem,
139			int thischain[], int chainlen, int t)
140			/* set random chain. returns 0 if not random, 1 if random, -1 on error */
141			{
142			int hop;
143			int err = 0;
144
145			assert(t == 0 \|\| t == 1);
146
147			for (hop = 0; hop < chainlen; hop++)
148			if (thischain[hop] == 0) {
149			int select[MAXREM];
150			int randavail = 0;
151			int i;
152
153			err = 1;
154			for (i = 1; i < maxrem; i++)
155			select[i] = ((remailer[i].flags.mix && t == 0) \|\|
156			(remailer[i].flags.pgp && remailer[i].flags.ek && t == 1))
157			&& remailer[i].info[t].reliability >= 100 * MINREL &&
158			remailer[i].info[t].latency <= MAXLAT,
159			randavail += select[i];
160
161			for (i = hop - DISTANCE; i <= hop + DISTANCE; i++)
162			if (i >= 0 && i < chainlen && select[thischain[i]])
163			select[thischain[i]] = 0, randavail--;
164
165			if (randavail < 1) {
166			err = -1;
167			goto end;
168			}
169			do
170			thischain[hop] = rnd_number(maxrem - 1) + 1;
171			while (!select[thischain[hop]]);
172			}
173			end:
174			return (err);
175			}
176
177			int mix_encrypt(int type, BUFFER message, char chainstr, int numcopies,
178			BUFFER *chainlist)
179			{
180			return (mix2_encrypt(type, message, chainstr, numcopies, chainlist));
181			}
182
183			/* float chain_reliablity(char *chain, int chaintype,
184			char *reliability_string);
185			*
186			* Compute reliablity of a chain.
187			*
188			* We get the reliablity of the chain by multiplying the reliablity of
189			* every remailer in the chain. The return value is the reliablity of
190			* the chain, or a negative number if the reliablity can not be
191			* calculated. There are two reasons why may not be able to calculated
192			* the reliablity: A remailer in the chain is selected randomly, or we
193			* don't have statistics about one of the remailers in the chain.
194			* remailer_type indicates the remailer type:
195			* 0 = Mixmaster, 1 = Cypherpunk
196			*
197			* If reliability_string is non-NULL, the reliability is also returned
198			* as a string in this variable. The size of the string must be at
199			* least 9 characters!
200			*
201			* This function has been added by Gerd Beuster. (gb@uni-koblenz.de)
202			--------------------------------------------------------------------/
203
204			float chain_reliability(char *chain, int chaintype,
205			char *reliability_string){
206
207			float acc_reliability = 1; /* Accumulated reliablity */
208			char name_start, name_end; /* temporary pointers used
209			in string scanning */
210			char remailer_name[20]; /* The length of the array is taken from mix3.h. */
211			int error = 0;
212			int maxrem;
213			int i;
214			REMAILER remailer[MAXREM];
215
216			/* chaintype 0=mix 1=ek 2=newnym */
217			assert((chaintype == 0) \|\| (chaintype == 1));
218			maxrem = (chaintype == 0 ? mix2_rlist(remailer) : t1_rlist(remailer));
219
220			/* Dissect chain */
221			name_start = chain;
222			name_end = chain;
223			while(name_end != '\0'){ / While string not scanned completely */
224			do /* Get next remailer */
225			name_end+=sizeof(char);
226			while( (name_end != ',') && (name_end != '\0'));
227			strncpy(remailer_name, name_start,
228			(name_end - name_start) / sizeof(char) + 1*sizeof(char));
229			remailer_name[name_end-name_start]='\0';
230			/* Lookup reliablity for remailer remailer_name */
231			for(i=0;
232			(i < maxrem) && (strcmp(remailer[i].name, remailer_name) != 0);
233			i++);
234			if(!strcmp(remailer[i].name, remailer_name)) /* Found it! */
235			acc_reliability *=
236			((float) remailer[i].info[chaintype].reliability) / 10000;
237			else
238			error = 1; /* Did not find this remailer. We can't calculate
239			the reliablity for the whole chain. */
240			name_start = name_end+sizeof(char);
241			}
242
243			if(error \|\| (name_start==name_end))
244			acc_reliability = -1;
245
246			/* Convert reliability into string, if appropriate */
247			if(reliability_string){
248			if(acc_reliability < 0)
249			sprintf(reliability_string, " n/a ");
250			else{
251			sprintf(reliability_string, "%6.2f", acc_reliability*100);
252			(reliability_string+6sizeof(char)) = '%';
253			}
254			}
255
256			return acc_reliability;
257			}
258