extensions/ip_cloaking_4.0.c

   1 /*
   2  * Charybdis: an advanced ircd
   3  * ip_cloaking.c: provide user hostname cloaking
   4  *
   5  * Written originally by nenolod, altered to use FNV by Elizabeth in 2008
   6  */
   7
   8 #include "stdinc.h"
   9 #include "modules.h"
  10 #include "hook.h"
  11 #include "client.h"
  12 #include "ircd.h"
  13 #include "send.h"
  14 #include "hash.h"
  15 #include "s_conf.h"
  16 #include "s_user.h"
  17 #include "s_serv.h"
  18 #include "numeric.h"
  19
  20 static int
  21 _modinit(void)
  22 {
  23         /* add the usermode to the available slot */
  24         user_modes['x'] = find_umode_slot();
  25         construct_umodebuf();
  26
  27         return 0;
  28 }
  29
  30 static void
  31 _moddeinit(void)
  32 {
  33         /* disable the umode and remove it from the available list */
  34         user_modes['x'] = 0;
  35         construct_umodebuf();
  36 }
  37
  38 static void check_umode_change(void *data);
  39 static void check_new_user(void *data);
  40 mapi_hfn_list_av1 ip_cloaking_hfnlist[] = {
  41         { "umode_changed", (hookfn) check_umode_change },
  42         { "new_local_user", (hookfn) check_new_user },
  43         { NULL, NULL }
  44 };
  45
  46 DECLARE_MODULE_AV1(ip_cloaking, _modinit, _moddeinit, NULL, NULL,
  47                         ip_cloaking_hfnlist, "$Revision: 3526 $");
  48
  49 static void
  50 distribute_hostchange(struct Client *client)
  51 {
  52         if (irccmp(client->host, client->orighost))
  53                 sendto_one_numeric(client, RPL_HOSTHIDDEN, "%s :is now your hidden host",
  54                         client->host);
  55         else
  56                 sendto_one_numeric(client, RPL_HOSTHIDDEN, "%s :hostname reset",
  57                         client->host);
  58
  59         sendto_server(NULL, NULL,
  60                 CAP_EUID | CAP_TS6, NOCAPS, ":%s CHGHOST %s :%s",
  61                 use_id(&me), use_id(client), client->host);
  62         sendto_server(NULL, NULL,
  63                 CAP_TS6, CAP_EUID, ":%s ENCAP * CHGHOST %s :%s",
  64                 use_id(&me), use_id(client), client->host);
  65         if (irccmp(client->host, client->orighost))
  66                 SetDynSpoof(client);
  67         else
  68                 ClearDynSpoof(client);
  69 }
  70
  71 static void
  72 do_host_cloak_ip(const char *inbuf, char *outbuf)
  73 {
  74         /* None of the characters in this table can be valid in an IP */
  75         char chartable[] = "ghijklmnopqrstuvwxyz";
  76         char *tptr;
  77         uint32_t accum = fnv_hash((const unsigned char*) inbuf, 32);
  78         int sepcount = 0;
  79         int totalcount = 0;
  80         int ipv6 = 0;
  81
  82         rb_strlcpy(outbuf, inbuf, HOSTLEN + 1);
  83
  84         if (strchr(outbuf, ':'))
  85         {
  86                 ipv6 = 1;
  87
  88                 /* Damn you IPv6...
  89                  * We count the number of colons so we can calculate how much
  90                  * of the host to cloak. This is because some hostmasks may not
  91                  * have as many octets as we'd like.
  92                  *
  93                  * We have to do this ahead of time because doing this during
  94                  * the actual cloaking would get ugly
  95                  */
  96                 for (tptr = outbuf; *tptr != '\0'; tptr++)
  97                         if (*tptr == ':')
  98                                 totalcount++;
  99         }
 100         else if (!strchr(outbuf, '.'))
 101                 return;
 102
 103         for (tptr = outbuf; *tptr != '\0'; tptr++)
 104         {
 105                 if (*tptr == ':' || *tptr == '.')
 106                 {
 107                         sepcount++;
 108                         continue;
 109                 }
 110
 111                 if (ipv6 && sepcount < totalcount / 2)
 112                         continue;
 113
 114                 if (!ipv6 && sepcount < 2)
 115                         continue;
 116
 117                 *tptr = chartable[(*tptr + accum) % 20];
 118                 accum = (accum << 1) | (accum >> 31);
 119         }
 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         uint32_t accum = fnv_hash((const unsigned char*) inbuf, 32);
 128
 129         rb_strlcpy(outbuf, inbuf, HOSTLEN + 1);
 130
 131         /* pass 1: scramble first section of hostname using base26
 132          * alphabet toasted against the FNV hash 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                 /* Rotate one bit to avoid all digits being turned odd or even */
 147                 accum = (accum << 1) | (accum >> 31);
 148         }
 149
 150         /* pass 2: scramble each number in the address */
 151         for (tptr = outbuf; *tptr != '\0'; tptr++)
 152         {
 153                 if (isdigit(*tptr))
 154                         *tptr = '0' + (*tptr + accum) % 10;
 155
 156                 accum = (accum << 1) | (accum >> 31);
 157         }
 158 }
 159
 160 static void
 161 check_umode_change(void *vdata)
 162 {
 163         hook_data_umode_changed *data = (hook_data_umode_changed *)vdata;
 164         struct Client *source_p = data->client;
 165
 166         if (!MyClient(source_p))
 167                 return;
 168
 169         /* didn't change +h umode, we don't need to do anything */
 170         if (!((data->oldumodes ^ source_p->umodes) & user_modes['x']))
 171                 return;
 172
 173         if (source_p->umodes & user_modes['x'])
 174         {
 175                 if (IsIPSpoof(source_p) || source_p->localClient->mangledhost == NULL || (IsDynSpoof(source_p) && strcmp(source_p->host, source_p->localClient->mangledhost)))
 176                 {
 177                         source_p->umodes &= ~user_modes['x'];
 178                         return;
 179                 }
 180                 if (strcmp(source_p->host, source_p->localClient->mangledhost))
 181                 {
 182                         rb_strlcpy(source_p->host, source_p->localClient->mangledhost, HOSTLEN + 1);
 183                         distribute_hostchange(source_p);
 184                 }
 185                 else /* not really nice, but we need to send this numeric here */
 186                         sendto_one_numeric(source_p, RPL_HOSTHIDDEN, "%s :is now your hidden host",
 187                                 source_p->host);
 188         }
 189         else if (!(source_p->umodes & user_modes['x']))
 190         {
 191                 if (source_p->localClient->mangledhost != NULL &&
 192                                 !strcmp(source_p->host, source_p->localClient->mangledhost))
 193                 {
 194                         rb_strlcpy(source_p->host, source_p->orighost, HOSTLEN + 1);
 195                         distribute_hostchange(source_p);
 196                 }
 197         }
 198 }
 199
 200 static void
 201 check_new_user(void *vdata)
 202 {
 203         struct Client *source_p = (void *)vdata;
 204
 205         if (IsIPSpoof(source_p))
 206         {
 207                 source_p->umodes &= ~user_modes['x'];
 208                 return;
 209         }
 210         source_p->localClient->mangledhost = rb_malloc(HOSTLEN + 1);
 211         if (!irccmp(source_p->orighost, source_p->sockhost))
 212                 do_host_cloak_ip(source_p->orighost, source_p->localClient->mangledhost);
 213         else
 214                 do_host_cloak_host(source_p->orighost, source_p->localClient->mangledhost);
 215         if (IsDynSpoof(source_p))
 216                 source_p->umodes &= ~user_modes['x'];
 217         if (source_p->umodes & user_modes['x'])
 218         {
 219                 rb_strlcpy(source_p->host, source_p->localClient->mangledhost, sizeof(source_p->host));
 220                 if (irccmp(source_p->host, source_p->orighost))
 221                         SetDynSpoof(source_p);
 222         }
 223 }
 224