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_p, char *newhost)
  51 {
  52         if (newhost != client_p->orighost)
  53                 sendto_one_numeric(client_p, RPL_HOSTHIDDEN, "%s :is now your hidden host",
  54                         client_p->host);
  55         else
  56                 sendto_one_numeric(client_p, RPL_HOSTHIDDEN, "%s :hostname reset",
  57                         client_p->host);
  58
  59         sendto_server(NULL, NULL,
  60                 CAP_EUID | CAP_TS6, NOCAPS, ":%s CHGHOST %s :%s",
  61                 use_id(&me), use_id(client_p), client_p->host);
  62         sendto_server(NULL, NULL,
  63                 CAP_TS6, CAP_EUID, ":%s ENCAP * CHGHOST %s :%s",
  64                 use_id(&me), use_id(client_p), client_p->host);
  65
  66         change_nick_user_host(client_p, client_p->name, client_p->username, newhost, 0, "Changing host");
  67
  68         if (newhost != client_p->orighost)
  69                 SetDynSpoof(client_p);
  70         else
  71                 ClearDynSpoof(client_p);
  72 }
  73
  74 static void
  75 do_host_cloak_ip(const char *inbuf, char *outbuf)
  76 {
  77         /* None of the characters in this table can be valid in an IP */
  78         char chartable[] = "ghijklmnopqrstuvwxyz";
  79         char *tptr;
  80         uint32_t accum = fnv_hash((const unsigned char*) inbuf, 32);
  81         int sepcount = 0;
  82         int totalcount = 0;
  83         int ipv6 = 0;
  84
  85         rb_strlcpy(outbuf, inbuf, HOSTLEN + 1);
  86
  87         if (strchr(outbuf, ':'))
  88         {
  89                 ipv6 = 1;
  90
  91                 /* Damn you IPv6...
  92                  * We count the number of colons so we can calculate how much
  93                  * of the host to cloak. This is because some hostmasks may not
  94                  * have as many octets as we'd like.
  95                  *
  96                  * We have to do this ahead of time because doing this during
  97                  * the actual cloaking would get ugly
  98                  */
  99                 for (tptr = outbuf; *tptr != '\0'; tptr++)
 100                         if (*tptr == ':')
 101                                 totalcount++;
 102         }
 103         else if (!strchr(outbuf, '.'))
 104                 return;
 105
 106         for (tptr = outbuf; *tptr != '\0'; tptr++)
 107         {
 108                 if (*tptr == ':' || *tptr == '.')
 109                 {
 110                         sepcount++;
 111                         continue;
 112                 }
 113
 114                 if (ipv6 && sepcount < totalcount / 2)
 115                         continue;
 116
 117                 if (!ipv6 && sepcount < 2)
 118                         continue;
 119
 120                 *tptr = chartable[(*tptr + accum) % 20];
 121                 accum = (accum << 1) | (accum >> 31);
 122         }
 123 }
 124
 125 static void
 126 do_host_cloak_host(const char *inbuf, char *outbuf)
 127 {
 128         char b26_alphabet[] = "abcdefghijklmnopqrstuvwxyz";
 129         char *tptr;
 130         uint32_t accum = fnv_hash((const unsigned char*) inbuf, 32);
 131
 132         rb_strlcpy(outbuf, inbuf, HOSTLEN + 1);
 133
 134         /* pass 1: scramble first section of hostname using base26
 135          * alphabet toasted against the FNV hash of the string.
 136          *
 137          * numbers are not changed at this time, only letters.
 138          */
 139         for (tptr = outbuf; *tptr != '\0'; tptr++)
 140         {
 141                 if (*tptr == '.')
 142                         break;
 143
 144                 if (isdigit(*tptr) || *tptr == '-')
 145                         continue;
 146
 147                 *tptr = b26_alphabet[(*tptr + accum) % 26];
 148
 149                 /* Rotate one bit to avoid all digits being turned odd or even */
 150                 accum = (accum << 1) | (accum >> 31);
 151         }
 152
 153         /* pass 2: scramble each number in the address */
 154         for (tptr = outbuf; *tptr != '\0'; tptr++)
 155         {
 156                 if (isdigit(*tptr))
 157                         *tptr = '0' + (*tptr + accum) % 10;
 158
 159                 accum = (accum << 1) | (accum >> 31);
 160         }
 161 }
 162
 163 static void
 164 check_umode_change(void *vdata)
 165 {
 166         hook_data_umode_changed *data = (hook_data_umode_changed *)vdata;
 167         struct Client *source_p = data->client;
 168
 169         if (!MyClient(source_p))
 170                 return;
 171
 172         /* didn't change +h umode, we don't need to do anything */
 173         if (!((data->oldumodes ^ source_p->umodes) & user_modes['x']))
 174                 return;
 175
 176         if (source_p->umodes & user_modes['x'])
 177         {
 178                 if (IsIPSpoof(source_p) || source_p->localClient->mangledhost == NULL || (IsDynSpoof(source_p) && strcmp(source_p->host, source_p->localClient->mangledhost)))
 179                 {
 180                         source_p->umodes &= ~user_modes['x'];
 181                         return;
 182                 }
 183                 if (strcmp(source_p->host, source_p->localClient->mangledhost))
 184                 {
 185                         distribute_hostchange(source_p, source_p->localClient->mangledhost);
 186                 }
 187                 else /* not really nice, but we need to send this numeric here */
 188                         sendto_one_numeric(source_p, RPL_HOSTHIDDEN, "%s :is now your hidden host",
 189                                 source_p->host);
 190         }
 191         else if (!(source_p->umodes & user_modes['x']))
 192         {
 193                 if (source_p->localClient->mangledhost != NULL &&
 194                                 !strcmp(source_p->host, source_p->localClient->mangledhost))
 195                 {
 196                         distribute_hostchange(source_p, source_p->orighost);
 197                 }
 198         }
 199 }
 200
 201 static void
 202 check_new_user(void *vdata)
 203 {
 204         struct Client *source_p = (void *)vdata;
 205
 206         if (IsIPSpoof(source_p))
 207         {
 208                 source_p->umodes &= ~user_modes['x'];
 209                 return;
 210         }
 211         source_p->localClient->mangledhost = rb_malloc(HOSTLEN + 1);
 212         if (!irccmp(source_p->orighost, source_p->sockhost))
 213                 do_host_cloak_ip(source_p->orighost, source_p->localClient->mangledhost);
 214         else
 215                 do_host_cloak_host(source_p->orighost, source_p->localClient->mangledhost);
 216         if (IsDynSpoof(source_p))
 217                 source_p->umodes &= ~user_modes['x'];
 218         if (source_p->umodes & user_modes['x'])
 219         {
 220                 rb_strlcpy(source_p->host, source_p->localClient->mangledhost, sizeof(source_p->host));
 221                 if (irccmp(source_p->host, source_p->orighost))
 222                         SetDynSpoof(source_p);
 223         }
 224 }
 225