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/* Mixmaster version 3 -- (C) 1999 Anonymizer Inc.
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Mixmaster may be redistributed and modified under certain conditions.
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This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF
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ANY KIND, either express or implied. See the file COPYRIGHT for
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details.
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Prepare messages for remailer chain
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$Id: chain.c,v 1.15 2003/05/22 14:44:55 weaselp Exp $ */
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#include "mix3.h"
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#include <string.h>
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#include <ctype.h>
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#include <assert.h>
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#include <stdlib.h>
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void clienterr(BUFFER *msgbuf, char *err)
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{
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if (msgbuf) {
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buf_sets(msgbuf, "Error: ");
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buf_appends(msgbuf, err);
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} else
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errlog(ERRORMSG, "%s\n", err);
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}
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void parse_badchains(int badchains[MAXREM][MAXREM], char *file, char *startindicator, REMAILER *remailer, int maxrem) {
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int i,j;
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FILE *list;
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char line[LINELEN];
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if (!badchains)
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return;
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for (i = 0; i < maxrem; i++ )
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for (j = 0; j < maxrem; j++ )
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badchains[i][j] = 0;
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list = mix_openfile(TYPE2REL, "r");
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if (list != NULL) {
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while (fgets(line, sizeof(line), list) != NULL &&
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!strleft(line, startindicator)) ;
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while (fgets(line, sizeof(line), list) != NULL &&
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strleft(line, "(")) {
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char *left, *right, *tmp;
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int lefti, righti;
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left = line + 1;
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while (*left == ' ')
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left ++;
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tmp = left + 1;
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while (*tmp != ' ' && *tmp != '\0' && *tmp != ')')
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tmp ++;
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if (*tmp == '\0' || *tmp == ')')
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/* parsing this line failed */
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continue;
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*tmp = '\0';
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right = tmp+1;
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while (*right == ' ')
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right ++;
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tmp = right + 1;
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while (*tmp != ' ' && *tmp != '\0' && *tmp != ')')
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tmp ++;
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if (*tmp == '\0')
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/* parsing this line failed */
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continue;
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*tmp = '\0';
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lefti = -1;
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righti = -1;
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for (i = 1; i < maxrem; i++) {
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if (strcmp(remailer[i].name, left) == 0)
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lefti = i;
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if (strcmp(remailer[i].name, right) == 0)
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righti = i;
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}
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if (strcmp(left, "*") == 0)
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lefti = 0;
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if (strcmp(right, "*") == 0)
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righti = 0;
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if (lefti == -1 || righti == -1)
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/* we don't know about one or both remailers */
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continue;
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badchains[lefti][righti] = 1;
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}
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fclose(list);
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/* If some broken chain includes all remailers (*) mark it broken for
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* every single remailer - this simplifies handling in other places */
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for (i=1; i < maxrem; i++ ) {
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if (badchains[0][i])
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for (j=1; j < maxrem; j++ )
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badchains[j][i] = 1;
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if (badchains[i][0])
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for (j=1; j < maxrem; j++ )
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badchains[i][j] = 1;
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}
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}
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}
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int chain_select(int hop[], char *chainstr, int maxrem, REMAILER *remailer,
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int type, BUFFER *feedback)
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{
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int len = 0;
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int i, j, k;
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BUFFER *chain, *selected, *addr;
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chain = buf_new();
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selected = buf_new();
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addr = buf_new();
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if (chainstr == NULL || chainstr[0] == '\0')
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buf_sets(chain, CHAIN);
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else
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buf_sets(chain, chainstr);
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/* put the chain backwards: final hop is in hop[0] */
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for (i = chain->length; i >= 0; i--)
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if (i == 0 || chain->data[i - 1] <= ' ' || chain->data[i - 1] == ','
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|| chain->data[i - 1] == ';' || chain->data[i - 1] == ':') {
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for (j = i; isspace(chain->data[j]);) /* ignore whitespace */
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j++;
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if (chain->data[j] == '\0')
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break;
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if (chain->data[j] == '*')
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k = 0;
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#if 0
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else if (isdigit(chain->data[j]))
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k = atoi(chain->data + j);
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#endif /* 0 */
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else {
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buf_sets(selected, chain->data + j);
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rfc822_addr(selected, addr);
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buf_clear(selected);
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buf_getline(addr, selected);
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if (!selected->length)
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buf_sets(selected, chain->data + j);
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for (k = 0; k < maxrem; k++)
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if (((remailer[k].flags.mix && type == 0) ||
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(remailer[k].flags.cpunk && type == 1) ||
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(remailer[k].flags.newnym && type == 2)) &&
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(streq(remailer[k].name, selected->data) ||
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strieq(remailer[k].addr, selected->data) ||
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(selected->data[0] == '@' && strifind(remailer[k].addr,
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selected->data))))
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break;
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}
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if (k < 0 || k >= maxrem) {
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if (feedback != NULL) {
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buf_appendf(feedback, "No such remailer: %b", selected);
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buf_nl(feedback);
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}
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#if 0
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k = 0;
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#else /* end of 0 */
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len = -1;
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goto end;
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#endif /* else not 0 */
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}
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hop[len++] = k;
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if (len >= 20) { /* array passed in is has length 20 */
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if (feedback != NULL) {
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buf_appends(feedback, "Chain too long.\n");
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}
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break;
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}
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if (i > 0)
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chain->data[i - 1] = '\0';
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}
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end:
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buf_free(chain);
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buf_free(selected);
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buf_free(addr);
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return len;
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}
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int chain_randfinal(int type, REMAILER *remailer, int badchains[MAXREM][MAXREM], int maxrem, int rtype, int chain[], int chainlen)
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{
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int randavail = 0;
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int i;
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int t;
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int select[MAXREM];
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int secondtolasthop = (chainlen <= 1 ? -1 : chain[1]);
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t = rtype;
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if (rtype == 2)
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t = 1;
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/* select a random final hop */
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for (i = 1; i < maxrem; i++) {
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select[i] =
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((remailer[i].flags.mix && rtype == 0) || /* remailer supports type */
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(remailer[i].flags.pgp && remailer[i].flags.ek && rtype == 1) ||
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(remailer[i].flags.newnym && rtype == 2)) &&
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remailer[i].info[t].reliability >= 100 * RELFINAL && /* remailer has sufficient reliability */
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remailer[i].info[t].latency <= MAXLAT && /* remailer has small enough latency */
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(type == MSG_NULL || !remailer[i].flags.middle) && /* remailer is not middleman */
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!remailer[i].flags.star_ex && /* remailer is not excluded from random selection */
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(remailer[i].flags.post || type != MSG_POST) && /* remailer supports post when this is a post */
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((secondtolasthop == -1) || !badchains[secondtolasthop][i]);
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/* we only have hop or the previous one can send to this (may be random) */
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randavail += select[i];
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}
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for (i = 1; i <= DISTANCE; i++)
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if (i < chainlen && select[chain[i]] && chain[i]) {
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select[chain[i]] = 0;
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randavail--;
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}
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assert(randavail >= 0);
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if (randavail == 0)
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i = -1;
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else {
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do
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i = rnd_number(maxrem - 1) + 1;
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while (!select[i]);
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}
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return (i);
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}
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int chain_rand(REMAILER *remailer, int badchains[MAXREM][MAXREM], int maxrem,
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int thischain[], int chainlen, int t)
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/* set random chain. returns 0 if not random, 1 if random, -1 on error */
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/* t... 0 for mixmaster Type II
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* 1 for cypherpunk Type I
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*/
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{
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int hop;
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int err = 0;
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assert(t == 0 || t == 1);
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for (hop = 0; hop < chainlen; hop++)
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if (thischain[hop] == 0) {
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int select[MAXREM];
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int randavail = 0;
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int i;
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err = 1;
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if (hop > 0)
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assert(thischain[hop-1]); /* we already should have chosen a remailer after this one */
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for (i = 1; i < maxrem; i++) {
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select[i] = ((remailer[i].flags.mix && t == 0) || /* remailer supports type */
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(remailer[i].flags.pgp && remailer[i].flags.ek && t == 1))
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&& remailer[i].info[t].reliability >= 100 * MINREL && /* remailer has sufficient reliability */
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!remailer[i].flags.star_ex && /* remailer is not excluded from random selection */
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remailer[i].info[t].latency <= MAXLAT && /* remailer has small enough latency */
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!badchains[i][0] && !badchains[i][thischain[hop-1]] && /* remailer can send to the next one */
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(hop == chainlen-1 || !badchains[thischain[hop+1]][i]);
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/* we are at the first hop or the previous one can send to this (may be random) */
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randavail += select[i];
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}
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for (i = hop - DISTANCE; i <= hop + DISTANCE; i++)
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if (i >= 0 && i < chainlen && select[thischain[i]] && thischain[i]) {
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select[thischain[i]] = 0;
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randavail--;
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}
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assert(randavail >= 0);
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if (randavail < 1) {
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err = -1;
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goto end;
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}
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do
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thischain[hop] = rnd_number(maxrem - 1) + 1;
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while (!select[thischain[hop]]);
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}
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end:
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return (err);
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}
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int mix_encrypt(int type, BUFFER *message, char *chainstr, int numcopies,
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BUFFER *chainlist)
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{
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return (mix2_encrypt(type, message, chainstr, numcopies, chainlist));
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}
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/* float chain_reliablity(char *chain, int chaintype,
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char *reliability_string);
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*
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* Compute reliablity of a chain.
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*
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* We get the reliablity of the chain by multiplying the reliablity of
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* every remailer in the chain. The return value is the reliablity of
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* the chain, or a negative number if the reliablity can not be
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* calculated. There are two reasons why may not be able to calculated
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* the reliablity: A remailer in the chain is selected randomly, or we
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* don't have statistics about one of the remailers in the chain.
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* remailer_type indicates the remailer type:
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* 0 = Mixmaster, 1 = Cypherpunk
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*
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* If reliability_string is non-NULL, the reliability is also returned
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* as a string in this variable. The size of the string must be at
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* least 9 characters!
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*
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* This function has been added by Gerd Beuster. (gb@uni-koblenz.de)
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*--------------------------------------------------------------------*/
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float chain_reliability(char *chain, int chaintype,
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char *reliability_string){
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float acc_reliability = 1; /* Accumulated reliablity */
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char *name_start, *name_end; /* temporary pointers used
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in string scanning */
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char remailer_name[20]; /* The length of the array is taken from mix3.h. */
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int error = 0;
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int maxrem;
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int i;
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int previous = -1;
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REMAILER remailer[MAXREM];
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int badchains[MAXREM][MAXREM];
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/* chaintype 0=mix 1=ek 2=newnym */
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assert((chaintype == 0) || (chaintype == 1));
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maxrem = (chaintype == 0 ? mix2_rlist(remailer, badchains) : t1_rlist(remailer, badchains));
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/* Dissect chain */
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name_start = chain;
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name_end = chain;
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while(*name_end != '\0'){ /* While string not scanned completely */
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do /* Get next remailer */
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name_end+=sizeof(char);
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while( (*name_end != ',') && (*name_end != '\0'));
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strncpy(remailer_name, name_start,
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(name_end - name_start) / sizeof(char) + 1*sizeof(char));
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remailer_name[name_end-name_start]='\0';
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/* Lookup reliablity for remailer remailer_name */
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for(i=0;
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(i < maxrem) && (strcmp(remailer[i].name, remailer_name) != 0);
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i++);
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if(!strcmp(remailer[i].name, remailer_name)) { /* Found it! */
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acc_reliability *=
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((float) remailer[i].info[chaintype].reliability) / 10000;
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if (previous != -1) {
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if (badchains[previous][i] || badchains[0][i])
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acc_reliability = 0;
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}
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previous = i;
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} else
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error = 1; /* Did not find this remailer. We can't calculate
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the reliablity for the whole chain. */
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name_start = name_end+sizeof(char);
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}
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if(error || (name_start==name_end))
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acc_reliability = -1;
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/* Convert reliability into string, if appropriate */
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if(reliability_string){
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if(acc_reliability < 0)
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sprintf(reliability_string, " n/a ");
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else{
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sprintf(reliability_string, "%6.2f", acc_reliability*100);
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*(reliability_string+6*sizeof(char)) = '%';
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}
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}
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return acc_reliability;
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}
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