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 "tools.h"
  13 #include "numeric.h"
  14
  15 /* if you're modifying this module, you'll probably to change this */
  16 #define KEY 0x13748cfa
  17
  18 static int
  19 _modinit(void)
  20 {
  21         /* add the usermode to the available slot */
  22         user_modes['h'] = find_umode_slot();
  23         construct_umodebuf();
  24
  25         return 0;
  26 }
  27
  28 static void
  29 _moddeinit(void)
  30 {
  31         /* disable the umode and remove it from the available list */
  32         user_modes['h'] = 0;
  33         construct_umodebuf();
  34 }
  35
  36 static void check_umode_change(void *data);
  37 static void check_new_user(void *data);
  38 mapi_hfn_list_av1 ip_cloaking_hfnlist[] = {
  39         { "umode_changed", (hookfn) check_umode_change },
  40         { "new_local_user", (hookfn) check_new_user },
  41         { NULL, NULL }
  42 };
  43
  44 DECLARE_MODULE_AV1(ip_cloaking, _modinit, _moddeinit, NULL, NULL,
  45                         ip_cloaking_hfnlist, "$Revision: 3526 $");
  46
  47 static void
  48 distribute_hostchange(struct Client *client)
  49 {
  50         if (irccmp(client->host, client->orighost))
  51                 sendto_one_numeric(client, RPL_HOSTHIDDEN, "%s :is now your hidden host",
  52                         client->host);
  53         else
  54                 sendto_one_numeric(client, RPL_HOSTHIDDEN, "%s :hostname reset",
  55                         client->host);
  56
  57         sendto_server(NULL, NULL,
  58                 CAP_EUID | CAP_TS6, NOCAPS, ":%s CHGHOST %s :%s",
  59                 use_id(&me), use_id(client), client->host);
  60         sendto_server(NULL, NULL,
  61                 CAP_TS6, CAP_EUID, ":%s ENCAP * CHGHOST %s :%s",
  62                 use_id(&me), use_id(client), client->host);
  63         sendto_server(NULL, NULL,
  64                 NOCAPS, CAP_TS6, ":%s ENCAP * CHGHOST %s :%s",
  65                 me.name, client->name, client->host);
  66         if (irccmp(client->host, client->orighost))
  67                 SetDynSpoof(client);
  68         else
  69                 ClearDynSpoof(client);
  70 }
  71
  72 #define Nval 0x8c3a48ac
  73 #define HOSTLEN 63
  74 #define INITDATA "98fwqefnoiqefv03f423t34gbv3vb89tg432t3b8" /* change this */
  75
  76 static inline unsigned int
  77 get_string_entropy(const char *inbuf)
  78 {
  79         unsigned int accum = 1;
  80
  81         while(*inbuf != '\0')
  82                 accum += *inbuf++;
  83
  84         return accum;
  85 }
  86
  87 /* calls get_string_entropy() and toasts it against INITDATA */
  88 static inline unsigned int
  89 get_string_weighted_entropy(const char *inbuf)
  90 {
  91         static int base_entropy = 0;
  92         unsigned int accum = get_string_entropy(inbuf);
  93
  94         /* initialize the algorithm if it is not yet ready */
  95         if (base_entropy == 0)
  96                 base_entropy = get_string_entropy(INITDATA);
  97
  98         return (Nval * accum) ^ base_entropy;
  99 }
 100
 101 static void
 102 do_host_cloak_ip(const char *inbuf, char *outbuf)
 103 {
 104         char *tptr;
 105         unsigned int accum = get_string_weighted_entropy(inbuf);
 106         char buf[HOSTLEN];
 107
 108         strncpy(buf, inbuf, HOSTLEN);
 109         tptr = strrchr(buf, '.');
 110
 111         if (tptr == NULL)
 112         {
 113                 strncpy(outbuf, inbuf, HOSTLEN);
 114                 return;
 115         }
 116
 117         *tptr++ = '\0';
 118
 119         snprintf(outbuf, HOSTLEN, "%s.%x", buf, accum);
 120 }
 121
 122 static void
 123 do_host_cloak_host(const char *inbuf, char *outbuf)
 124 {
 125         char b26_alphabet[] = "abcdefghijklmnopqrstuvwxyz";
 126         char *tptr;
 127         unsigned int accum = get_string_weighted_entropy(inbuf);
 128
 129         strncpy(outbuf, inbuf, HOSTLEN);
 130
 131         /* pass 1: scramble first section of hostname using base26
 132          * alphabet toasted against the weighted entropy of the string.
 133          *
 134          * numbers are not changed at this time, only letters.
 135          */
 136         for (tptr = outbuf; *tptr != '\0'; tptr++)
 137         {
 138                 if (*tptr == '.')
 139                         break;
 140
 141                 if (isdigit(*tptr) || *tptr == '-')
 142                         continue;
 143
 144                 *tptr = b26_alphabet[(*tptr * accum) % 26];
 145         }
 146
 147         /* pass 2: scramble each number in the address */
 148         for (tptr = outbuf; *tptr != '\0'; tptr++)
 149         {
 150                 if (isdigit(*tptr))
 151                 {
 152                         *tptr = 48 + ((*tptr * accum) % 10);
 153                 }
 154         }
 155 }
 156
 157 static void
 158 check_umode_change(void *vdata)
 159 {
 160         hook_data_umode_changed *data = (hook_data_umode_changed *)vdata;
 161         struct Client *source_p = data->client;
 162
 163         if (!MyClient(source_p))
 164                 return;
 165
 166         /* didn't change +h umode, we don't need to do anything */
 167         if (!((data->oldumodes ^ source_p->umodes) & user_modes['h']))
 168                 return;
 169
 170         if (source_p->umodes & user_modes['h'])
 171         {
 172                 if (IsIPSpoof(source_p) || source_p->localClient->mangledhost == NULL || (IsDynSpoof(source_p) && strcmp(source_p->host, source_p->localClient->mangledhost)))
 173                 {
 174                         source_p->umodes &= ~user_modes['h'];
 175                         return;
 176                 }
 177                 if (strcmp(source_p->host, source_p->localClient->mangledhost))
 178                 {
 179                         strlcpy(source_p->host, source_p->localClient->mangledhost, HOSTLEN);
 180                         distribute_hostchange(source_p);
 181                 }
 182                 else /* not really nice, but we need to send this numeric here */
 183                         sendto_one_numeric(source_p, RPL_HOSTHIDDEN, "%s :is now your hidden host",
 184                                 source_p->host);
 185         }
 186         else if (!(source_p->umodes & user_modes['h']))
 187         {
 188                 if (source_p->localClient->mangledhost != NULL &&
 189                                 !strcmp(source_p->host, source_p->localClient->mangledhost))
 190                 {
 191                         strlcpy(source_p->host, source_p->orighost, HOSTLEN);
 192                         distribute_hostchange(source_p);
 193                 }
 194         }
 195 }
 196
 197 static void
 198 check_new_user(void *vdata)
 199 {
 200         struct Client *source_p = (void *)vdata;
 201
 202         if (IsIPSpoof(source_p))
 203         {
 204                 source_p->umodes &= ~user_modes['h'];
 205                 return;
 206         }
 207         source_p->localClient->mangledhost = MyMalloc(HOSTLEN);
 208         if (!irccmp(source_p->orighost, source_p->sockhost))
 209                 do_host_cloak_ip(source_p->orighost, source_p->localClient->mangledhost);
 210         else
 211                 do_host_cloak_host(source_p->orighost, source_p->localClient->mangledhost);
 212         if (IsDynSpoof(source_p))
 213                 source_p->umodes &= ~user_modes['h'];
 214         if (source_p->umodes & user_modes['h'])
 215         {
 216                 strlcpy(source_p->host, source_p->localClient->mangledhost, sizeof(source_p->host));
 217                 if (irccmp(source_p->host, source_p->orighost))
 218                         SetDynSpoof(source_p);
 219         }
 220 }