extensions/ip_cloaking.c

   1 /* $Id: ip_cloaking.c 3526 2007-07-06 07:56:14Z nenolod $ */
   2
   3 #include "stdinc.h"
   4 #include "modules.h"
   5 #include "hook.h"
   6 #include "client.h"
   7 #include "ircd.h"
   8 #include "send.h"
   9 #include "s_conf.h"
  10 #include "s_user.h"
  11 #include "s_serv.h"
  12 #include "numeric.h"
  13
  14 /* if you're modifying this module, you'll probably to change this */
  15 #define KEY 0x13748cfa
  16
  17 static int
  18 _modinit(void)
  19 {
  20         /* add the usermode to the available slot */
  21         user_modes['h'] = find_umode_slot();
  22         construct_umodebuf();
  23
  24         return 0;
  25 }
  26
  27 static void
  28 _moddeinit(void)
  29 {
  30         /* disable the umode and remove it from the available list */
  31         user_modes['h'] = 0;
  32         construct_umodebuf();
  33 }
  34
  35 static void check_umode_change(void *data);
  36 static void check_new_user(void *data);
  37 mapi_hfn_list_av1 ip_cloaking_hfnlist[] = {
  38         { "umode_changed", (hookfn) check_umode_change },
  39         { "new_local_user", (hookfn) check_new_user },
  40         { NULL, NULL }
  41 };
  42
  43 DECLARE_MODULE_AV1(ip_cloaking, _modinit, _moddeinit, NULL, NULL,
  44                         ip_cloaking_hfnlist, "$Revision: 3526 $");
  45
  46 static void
  47 distribute_hostchange(struct Client *client)
  48 {
  49         if (irccmp(client->host, client->orighost))
  50                 sendto_one_numeric(client, RPL_HOSTHIDDEN, "%s :is now your hidden host",
  51                         client->host);
  52         else
  53                 sendto_one_numeric(client, RPL_HOSTHIDDEN, "%s :hostname reset",
  54                         client->host);
  55
  56         sendto_server(NULL, NULL,
  57                 CAP_EUID | CAP_TS6, NOCAPS, ":%s CHGHOST %s :%s",
  58                 use_id(&me), use_id(client), client->host);
  59         sendto_server(NULL, NULL,
  60                 CAP_TS6, CAP_EUID, ":%s ENCAP * CHGHOST %s :%s",
  61                 use_id(&me), use_id(client), client->host);
  62         if (irccmp(client->host, client->orighost))
  63                 SetDynSpoof(client);
  64         else
  65                 ClearDynSpoof(client);
  66 }
  67
  68 #define Nval 0x8c3a48ac
  69 #define HOSTLEN 63
  70 #define INITDATA "98fwqefnoiqefv03f423t34gbv3vb89tg432t3b8" /* change this */
  71
  72 static inline unsigned int
  73 get_string_entropy(const char *inbuf)
  74 {
  75         unsigned int accum = 1;
  76
  77         while(*inbuf != '\0')
  78                 accum += *inbuf++;
  79
  80         return accum;
  81 }
  82
  83 /* calls get_string_entropy() and toasts it against INITDATA */
  84 static inline unsigned int
  85 get_string_weighted_entropy(const char *inbuf)
  86 {
  87         static int base_entropy = 0;
  88         unsigned int accum = get_string_entropy(inbuf);
  89
  90         /* initialize the algorithm if it is not yet ready */
  91         if (base_entropy == 0)
  92                 base_entropy = get_string_entropy(INITDATA);
  93
  94         return (Nval * accum) ^ base_entropy;
  95 }
  96
  97 static void
  98 do_host_cloak_ip(const char *inbuf, char *outbuf)
  99 {
 100         char *tptr;
 101         unsigned int accum = get_string_weighted_entropy(inbuf);
 102         char buf[HOSTLEN];
 103
 104         strncpy(buf, inbuf, HOSTLEN);
 105         tptr = strrchr(buf, '.');
 106
 107         if (tptr == NULL)
 108         {
 109                 strncpy(outbuf, inbuf, HOSTLEN);
 110                 return;
 111         }
 112
 113         *tptr++ = '\0';
 114
 115         snprintf(outbuf, HOSTLEN, "%s.%x", buf, accum);
 116 }
 117
 118 static void
 119 do_host_cloak_host(const char *inbuf, char *outbuf)
 120 {
 121         char b26_alphabet[] = "abcdefghijklmnopqrstuvwxyz";
 122         char *tptr;
 123         unsigned int accum = get_string_weighted_entropy(inbuf);
 124
 125         strncpy(outbuf, inbuf, HOSTLEN);
 126
 127         /* pass 1: scramble first section of hostname using base26
 128          * alphabet toasted against the weighted entropy of the string.
 129          *
 130          * numbers are not changed at this time, only letters.
 131          */
 132         for (tptr = outbuf; *tptr != '\0'; tptr++)
 133         {
 134                 if (*tptr == '.')
 135                         break;
 136
 137                 if (isdigit(*tptr) || *tptr == '-')
 138                         continue;
 139
 140                 *tptr = b26_alphabet[(*tptr * accum) % 26];
 141         }
 142
 143         /* pass 2: scramble each number in the address */
 144         for (tptr = outbuf; *tptr != '\0'; tptr++)
 145         {
 146                 if (isdigit(*tptr))
 147                 {
 148                         *tptr = 48 + ((*tptr * accum) % 10);
 149                 }
 150         }
 151 }
 152
 153 static void
 154 check_umode_change(void *vdata)
 155 {
 156         hook_data_umode_changed *data = (hook_data_umode_changed *)vdata;
 157         struct Client *source_p = data->client;
 158
 159         if (!MyClient(source_p))
 160                 return;
 161
 162         /* didn't change +h umode, we don't need to do anything */
 163         if (!((data->oldumodes ^ source_p->umodes) & user_modes['h']))
 164                 return;
 165
 166         if (source_p->umodes & user_modes['h'])
 167         {
 168                 if (IsIPSpoof(source_p) || source_p->localClient->mangledhost == NULL || (IsDynSpoof(source_p) && strcmp(source_p->host, source_p->localClient->mangledhost)))
 169                 {
 170                         source_p->umodes &= ~user_modes['h'];
 171                         return;
 172                 }
 173                 if (strcmp(source_p->host, source_p->localClient->mangledhost))
 174                 {
 175                         rb_strlcpy(source_p->host, source_p->localClient->mangledhost, HOSTLEN);
 176                         distribute_hostchange(source_p);
 177                 }
 178                 else /* not really nice, but we need to send this numeric here */
 179                         sendto_one_numeric(source_p, RPL_HOSTHIDDEN, "%s :is now your hidden host",
 180                                 source_p->host);
 181         }
 182         else if (!(source_p->umodes & user_modes['h']))
 183         {
 184                 if (source_p->localClient->mangledhost != NULL &&
 185                                 !strcmp(source_p->host, source_p->localClient->mangledhost))
 186                 {
 187                         rb_strlcpy(source_p->host, source_p->orighost, HOSTLEN);
 188                         distribute_hostchange(source_p);
 189                 }
 190         }
 191 }
 192
 193 static void
 194 check_new_user(void *vdata)
 195 {
 196         struct Client *source_p = (void *)vdata;
 197
 198         if (IsIPSpoof(source_p))
 199         {
 200                 source_p->umodes &= ~user_modes['h'];
 201                 return;
 202         }
 203         source_p->localClient->mangledhost = rb_malloc(HOSTLEN);
 204         if (!irccmp(source_p->orighost, source_p->sockhost))
 205                 do_host_cloak_ip(source_p->orighost, source_p->localClient->mangledhost);
 206         else
 207                 do_host_cloak_host(source_p->orighost, source_p->localClient->mangledhost);
 208         if (IsDynSpoof(source_p))
 209                 source_p->umodes &= ~user_modes['h'];
 210         if (source_p->umodes & user_modes['h'])
 211         {
 212                 rb_strlcpy(source_p->host, source_p->localClient->mangledhost, sizeof(source_p->host));
 213                 if (irccmp(source_p->host, source_p->orighost))
 214                         SetDynSpoof(source_p);
 215         }
 216 }