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         sendto_server(NULL, NULL,
  63                 NOCAPS, CAP_TS6, ":%s ENCAP * CHGHOST %s :%s",
  64                 me.name, client->name, client->host);
  65         if (irccmp(client->host, client->orighost))
  66                 SetDynSpoof(client);
  67         else
  68                 ClearDynSpoof(client);
  69 }
  70
  71 #define Nval 0x8c3a48ac
  72 #define HOSTLEN 63
  73 #define INITDATA "98fwqefnoiqefv03f423t34gbv3vb89tg432t3b8" /* change this */
  74
  75 static inline unsigned int
  76 get_string_entropy(const char *inbuf)
  77 {
  78         unsigned int accum = 1;
  79
  80         while(*inbuf != '\0')
  81                 accum += *inbuf++;
  82
  83         return accum;
  84 }
  85
  86 /* calls get_string_entropy() and toasts it against INITDATA */
  87 static inline unsigned int
  88 get_string_weighted_entropy(const char *inbuf)
  89 {
  90         static int base_entropy = 0;
  91         unsigned int accum = get_string_entropy(inbuf);
  92
  93         /* initialize the algorithm if it is not yet ready */
  94         if (base_entropy == 0)
  95                 base_entropy = get_string_entropy(INITDATA);
  96
  97         return (Nval * accum) ^ base_entropy;
  98 }
  99
 100 static void
 101 do_host_cloak_ip(const char *inbuf, char *outbuf)
 102 {
 103         char *tptr;
 104         unsigned int accum = get_string_weighted_entropy(inbuf);
 105         char buf[HOSTLEN];
 106
 107         strncpy(buf, inbuf, HOSTLEN);
 108         tptr = strrchr(buf, '.');
 109
 110         if (tptr == NULL)
 111         {
 112                 strncpy(outbuf, inbuf, HOSTLEN);
 113                 return;
 114         }
 115
 116         *tptr++ = '\0';
 117
 118         snprintf(outbuf, HOSTLEN, "%s.%x", buf, accum);
 119 }
 120
 121 static void
 122 do_host_cloak_host(const char *inbuf, char *outbuf)
 123 {
 124         char b26_alphabet[] = "abcdefghijklmnopqrstuvwxyz";
 125         char *tptr;
 126         unsigned int accum = get_string_weighted_entropy(inbuf);
 127
 128         strncpy(outbuf, inbuf, HOSTLEN);
 129
 130         /* pass 1: scramble first section of hostname using base26
 131          * alphabet toasted against the weighted entropy of the string.
 132          *
 133          * numbers are not changed at this time, only letters.
 134          */
 135         for (tptr = outbuf; *tptr != '\0'; tptr++)
 136         {
 137                 if (*tptr == '.')
 138                         break;
 139
 140                 if (isdigit(*tptr) || *tptr == '-')
 141                         continue;
 142
 143                 *tptr = b26_alphabet[(*tptr * accum) % 26];
 144         }
 145
 146         /* pass 2: scramble each number in the address */
 147         for (tptr = outbuf; *tptr != '\0'; tptr++)
 148         {
 149                 if (isdigit(*tptr))
 150                 {
 151                         *tptr = 48 + ((*tptr * accum) % 10);
 152                 }
 153         }
 154 }
 155
 156 static void
 157 check_umode_change(void *vdata)
 158 {
 159         hook_data_umode_changed *data = (hook_data_umode_changed *)vdata;
 160         struct Client *source_p = data->client;
 161
 162         if (!MyClient(source_p))
 163                 return;
 164
 165         /* didn't change +h umode, we don't need to do anything */
 166         if (!((data->oldumodes ^ source_p->umodes) & user_modes['h']))
 167                 return;
 168
 169         if (source_p->umodes & user_modes['h'])
 170         {
 171                 if (IsIPSpoof(source_p) || source_p->localClient->mangledhost == NULL || (IsDynSpoof(source_p) && strcmp(source_p->host, source_p->localClient->mangledhost)))
 172                 {
 173                         source_p->umodes &= ~user_modes['h'];
 174                         return;
 175                 }
 176                 if (strcmp(source_p->host, source_p->localClient->mangledhost))
 177                 {
 178                         rb_strlcpy(source_p->host, source_p->localClient->mangledhost, HOSTLEN);
 179                         distribute_hostchange(source_p);
 180                 }
 181                 else /* not really nice, but we need to send this numeric here */
 182                         sendto_one_numeric(source_p, RPL_HOSTHIDDEN, "%s :is now your hidden host",
 183                                 source_p->host);
 184         }
 185         else if (!(source_p->umodes & user_modes['h']))
 186         {
 187                 if (source_p->localClient->mangledhost != NULL &&
 188                                 !strcmp(source_p->host, source_p->localClient->mangledhost))
 189                 {
 190                         rb_strlcpy(source_p->host, source_p->orighost, HOSTLEN);
 191                         distribute_hostchange(source_p);
 192                 }
 193         }
 194 }
 195
 196 static void
 197 check_new_user(void *vdata)
 198 {
 199         struct Client *source_p = (void *)vdata;
 200
 201         if (IsIPSpoof(source_p))
 202         {
 203                 source_p->umodes &= ~user_modes['h'];
 204                 return;
 205         }
 206         source_p->localClient->mangledhost = rb_malloc(HOSTLEN);
 207         if (!irccmp(source_p->orighost, source_p->sockhost))
 208                 do_host_cloak_ip(source_p->orighost, source_p->localClient->mangledhost);
 209         else
 210                 do_host_cloak_host(source_p->orighost, source_p->localClient->mangledhost);
 211         if (IsDynSpoof(source_p))
 212                 source_p->umodes &= ~user_modes['h'];
 213         if (source_p->umodes & user_modes['h'])
 214         {
 215                 rb_strlcpy(source_p->host, source_p->localClient->mangledhost, sizeof(source_p->host));
 216                 if (irccmp(source_p->host, source_p->orighost))
 217                         SetDynSpoof(source_p);
 218         }
 219 }