src/mod-blacklist.c

   1 /* Blacklist module for srvx 1.x
   2  * Copyright 2007 Michael Poole <mdpoole@troilus.org>
   3  *
   4  * This file is part of srvx.
   5  *
   6  * srvx is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with srvx; if not, write to the Free Software Foundation,
  18  * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
  19  */
  20
  21 #include "conf.h"
  22 #include "gline.h"
  23 #include "modcmd.h"
  24 #include "proto.h"
  25 #include "sar.h"
  26
  27 const char *blacklist_module_deps[] = { NULL };
  28
  29 struct dnsbl_zone {
  30     struct string_list reasons;
  31     const char *description;
  32     const char *reason;
  33     unsigned int duration;
  34     unsigned int mask;
  35     unsigned int debug : 1;
  36     char zone[1];
  37 };
  38
  39 struct dnsbl_data {
  40     char client_ip[IRC_NTOP_MAX_SIZE];
  41     char zone_name[1];
  42 };
  43
  44 static struct log_type *bl_log;
  45 static dict_t blacklist_zones; /* contains struct dnsbl_zone */
  46 static dict_t blacklist_hosts; /* maps IPs or hostnames to reasons from blacklist_reasons */
  47 static dict_t blacklist_reasons; /* maps strings to themselves (poor man's data sharing) */
  48
  49 static struct {
  50     struct userNode *debug_bot;
  51     struct chanNode *debug_channel;
  52     unsigned long gline_duration;
  53 } conf;
  54
  55 #if defined(GCC_VARMACROS)
  56 # define blacklist_debug(ARGS...) do { if (conf.debug_bot && conf.debug_channel) send_channel_notice(conf.debug_channel, conf.debug_bot, ARGS); } while (0)
  57 #elif defined(C99_VARMACROS)
  58 # define blacklist_debug(...) do { if (conf.debug_bot && conf.debug_channel) send_channel_notice(conf.debug_channel, conf.debug_bot, __VA_ARGS__); } while (0)
  59 #endif
  60
  61 static void
  62 do_expandos(char *output, unsigned int out_len, const char *input, ...)
  63 {
  64     va_list args;
  65     const char *key;
  66     const char *datum;
  67     char *found;
  68     unsigned int klen;
  69     unsigned int dlen;
  70     unsigned int rlen;
  71
  72     safestrncpy(output, input, out_len);
  73     va_start(args, input);
  74     while ((key = va_arg(args, const char*)) != NULL) {
  75         datum = va_arg(args, const char *);
  76         klen = strlen(key);
  77         dlen = strlen(datum);
  78         for (found = output; (found = strstr(output, key)) != NULL; found += dlen) {
  79             rlen = strlen(found + klen);
  80             if ((dlen > klen) && ((unsigned)(found + dlen + rlen - output) > out_len))
  81                 rlen = output + out_len - found - dlen;
  82             memmove(found + dlen, found + klen, rlen);
  83             memcpy(found, datum, dlen + 1);
  84         }
  85     }
  86     va_end(args);
  87 }
  88
  89 static void
  90 dnsbl_hit(struct sar_request *req, struct dns_header *hdr, struct dns_rr *rr, unsigned char *raw, unsigned int raw_size)
  91 {
  92     struct dnsbl_data *data;
  93     struct dnsbl_zone *zone;
  94     const char *message;
  95     char *txt;
  96     unsigned int mask;
  97     unsigned int pos;
  98     unsigned int len;
  99     unsigned int ii;
 100     char reason[MAXLEN];
 101     char target[IRC_NTOP_MAX_SIZE + 2];
 102
 103     /* Get the DNSBL zone (to make sure it has not disappeared in a rehash). */
 104     data = (struct dnsbl_data*)(req + 1);
 105     zone = dict_find(blacklist_zones, data->zone_name, NULL);
 106     if (!zone)
 107         return;
 108
 109     /* Scan the results. */
 110     for (mask = 0, ii = 0, txt = NULL; ii < hdr->ancount; ++ii) {
 111         pos = rr[ii].rd_start;
 112         switch (rr[ii].type) {
 113         case REQ_TYPE_A:
 114             if (rr[ii].rdlength != 4)
 115                 break;
 116             if (pos + 3 < raw_size)
 117                 mask |= (1 << raw[pos + 3]);
 118             break;
 119         case REQ_TYPE_TXT:
 120             len = raw[pos];
 121             txt = malloc(len + 1);
 122             memcpy(txt, raw + pos + 1, len);
 123             txt[len] = '\0';
 124             break;
 125         }
 126     }
 127
 128     /* Do we care about one of the masks we found? */
 129     if (mask & zone->mask) {
 130         /* See if a per-result message was provided. */
 131         for (ii = 0, message = NULL; mask && (ii < zone->reasons.used); ++ii, mask >>= 1) {
 132             if (0 == (mask & 1))
 133                 continue;
 134             if (NULL != (message = zone->reasons.list[ii]))
 135                 break;
 136         }
 137
 138         /* If not, use a standard fallback. */
 139         if (message == NULL) {
 140             message = zone->reason;
 141             if (message == NULL)
 142                 message = "client is blacklisted";
 143         }
 144
 145         /* Expand elements of the message as necessary. */
 146         do_expandos(reason, sizeof(reason), message, "%txt%", (txt ? txt : "(no-txt)"), "%ip%", data->client_ip, NULL);
 147
 148         if (zone->debug) {
 149             blacklist_debug("DNSBL match: [%s] %s (%s)", zone->zone, data->client_ip, reason);
 150         } else {
 151             /* Now generate the G-line. */
 152             target[0] = '*';
 153             target[1] = '@';
 154             strcpy(target + 2, data->client_ip);
 155             gline_add(self->name, target, zone->duration, reason, now, 1, 0);
 156         }
 157     }
 158     free(txt);
 159 }
 160
 161 static int
 162 blacklist_check_user(struct userNode *user)
 163 {
 164     static const char *hexdigits = "0123456789abcdef";
 165     dict_iterator_t it;
 166     const char *reason;
 167     const char *host;
 168     unsigned int dnsbl_len;
 169     unsigned int ii;
 170     char ip[IRC_NTOP_MAX_SIZE];
 171     char dnsbl_target[128];
 172
 173     /* Users added during burst should not be checked. */
 174     if (user->uplink->burst)
 175         return 0;
 176
 177     /* Users with bogus IPs are probably service bots. */
 178     if (!irc_in_addr_is_valid(user->ip))
 179         return 0;
 180
 181     /* Check local file-based blacklist. */
 182     irc_ntop(ip, sizeof(ip), &user->ip);
 183     reason = dict_find(blacklist_hosts, host = ip, NULL);
 184     if (reason == NULL) {
 185         reason = dict_find(blacklist_hosts, host = user->hostname, NULL);
 186     }
 187     if (reason != NULL) {
 188         char *target;
 189         target = alloca(strlen(host) + 3);
 190         target[0] = '*';
 191         target[1] = '@';
 192         strcpy(target + 2, host);
 193         gline_add(self->name, target, conf.gline_duration, reason, now, 1, 0);
 194     }
 195
 196     /* Figure out the base part of a DNS blacklist hostname. */
 197     if (irc_in_addr_is_ipv4(user->ip)) {
 198         dnsbl_len = snprintf(dnsbl_target, sizeof(dnsbl_target), "%d.%d.%d.%d.", user->ip.in6_8[15], user->ip.in6_8[14], user->ip.in6_8[13], user->ip.in6_8[12]);
 199     } else if (irc_in_addr_is_ipv6(user->ip)) {
 200         for (ii = 0; ii < 16; ++ii) {
 201             dnsbl_target[ii * 4 + 0] = hexdigits[user->ip.in6_8[15 - ii] & 15];
 202             dnsbl_target[ii * 4 + 1] = '.';
 203             dnsbl_target[ii * 4 + 2] = hexdigits[user->ip.in6_8[15 - ii] >> 4];
 204             dnsbl_target[ii * 4 + 3] = '.';
 205         }
 206         dnsbl_len = 48;
 207     } else {
 208         return 0;
 209     }
 210
 211     /* Start a lookup for the appropriate hostname in each DNSBL. */
 212     for (it = dict_first(blacklist_zones); it; it = iter_next(it)) {
 213         struct dnsbl_data *data;
 214         struct sar_request *req;
 215         const char *zone;
 216
 217         zone = iter_key(it);
 218         safestrncpy(dnsbl_target + dnsbl_len, zone, sizeof(dnsbl_target) - dnsbl_len);
 219         req = sar_request_simple(sizeof(*data) + strlen(zone), dnsbl_hit, NULL, dnsbl_target, REQ_QTYPE_ALL, NULL);
 220         if (req) {
 221             data = (struct dnsbl_data*)(req + 1);
 222             strcpy(data->client_ip, ip);
 223             strcpy(data->zone_name, zone);
 224         }
 225     }
 226
 227     return 0;
 228 }
 229
 230 static void
 231 blacklist_load_file(const char *filename, const char *default_reason)
 232 {
 233     FILE *file;
 234     const char *reason;
 235     char *mapped_reason;
 236     char *sep;
 237     size_t len;
 238     char linebuf[MAXLEN];
 239
 240     if (!filename)
 241         return;
 242     if (!default_reason)
 243         default_reason = "client is blacklisted";
 244     file = fopen(filename, "r");
 245     if (!file) {
 246         log_module(bl_log, LOG_ERROR, "Unable to open %s for reading: %s", filename, strerror(errno));
 247         return;
 248     }
 249     log_module(bl_log, LOG_DEBUG, "Loading blacklist from %s.", filename);
 250     while (fgets(linebuf, sizeof(linebuf), file)) {
 251         /* Trim whitespace from end of line. */
 252         len = strlen(linebuf);
 253         while (isspace(linebuf[len-1]))
 254             linebuf[--len] = '\0';
 255
 256         /* Figure out which reason string we should use. */
 257         reason = default_reason;
 258         sep = strchr(linebuf, ' ');
 259         if (sep) {
 260             *sep++ = '\0';
 261             while (isspace(*sep))
 262                 sep++;
 263             if (*sep != '\0')
 264                 reason = sep;
 265         }
 266
 267         /* See if the reason string is already known. */
 268         mapped_reason = dict_find(blacklist_reasons, reason, NULL);
 269         if (!mapped_reason) {
 270             mapped_reason = strdup(reason);
 271             dict_insert(blacklist_reasons, mapped_reason, (char*)mapped_reason);
 272         }
 273
 274         /* Store the blacklist entry. */
 275         dict_insert(blacklist_hosts, strdup(linebuf), mapped_reason);
 276     }
 277     fclose(file);
 278 }
 279
 280 static void
 281 dnsbl_zone_free(void *pointer)
 282 {
 283     struct dnsbl_zone *zone;
 284     zone = pointer;
 285     free(zone->reasons.list);
 286     free(zone);
 287 }
 288
 289 static void
 290 blacklist_conf_read(void)
 291 {
 292     dict_t node;
 293     dict_t subnode;
 294     const char *str1;
 295     const char *str2;
 296
 297     dict_delete(blacklist_zones);
 298     blacklist_zones = dict_new();
 299     dict_set_free_data(blacklist_zones, dnsbl_zone_free);
 300
 301     dict_delete(blacklist_hosts);
 302     blacklist_hosts = dict_new();
 303     dict_set_free_keys(blacklist_hosts, free);
 304
 305     dict_delete(blacklist_reasons);
 306     blacklist_reasons = dict_new();
 307     dict_set_free_keys(blacklist_reasons, free);
 308
 309     node = conf_get_data("modules/blacklist", RECDB_OBJECT);
 310     if (node == NULL)
 311         return;
 312
 313     str1 = database_get_data(node, "debug_bot", RECDB_QSTRING);
 314     if (str1)
 315         conf.debug_bot = GetUserH(str1);
 316
 317     str1 = database_get_data(node, "debug_channel", RECDB_QSTRING);
 318     if (conf.debug_bot && str1) {
 319         str2 = database_get_data(node, "debug_channel_modes", RECDB_QSTRING);
 320         if (!str2)
 321             str2 = "+tinms";
 322         conf.debug_channel = AddChannel(str1, now, str2, NULL, NULL);
 323         AddChannelUser(conf.debug_bot, conf.debug_channel)->modes |= MODE_CHANOP;
 324     } else {
 325         conf.debug_channel = NULL;
 326     }
 327
 328     str1 = database_get_data(node, "file", RECDB_QSTRING);
 329     str2 = database_get_data(node, "file_reason", RECDB_QSTRING);
 330     blacklist_load_file(str1, str2);
 331
 332     str1 = database_get_data(node, "gline_duration", RECDB_QSTRING);
 333     if (str1 == NULL)
 334         str1 = "1h";
 335     conf.gline_duration = ParseInterval(str1);
 336
 337     subnode = database_get_data(node, "dnsbl", RECDB_OBJECT);
 338     if (subnode) {
 339         static const char *reason_prefix = "reason_";
 340         static const unsigned int max_id = 255;
 341         struct dnsbl_zone *zone;
 342         dict_iterator_t it;
 343         dict_iterator_t it2;
 344         dict_t dnsbl;
 345         unsigned int id;
 346
 347         for (it = dict_first(subnode); it; it = iter_next(it)) {
 348             dnsbl = GET_RECORD_OBJECT((struct record_data*)iter_data(it));
 349             if (!dnsbl)
 350                 continue;
 351
 352             zone = malloc(sizeof(*zone) + strlen(iter_key(it)));
 353             strcpy(zone->zone, iter_key(it));
 354             zone->description = database_get_data(dnsbl, "description", RECDB_QSTRING);
 355             zone->reason = database_get_data(dnsbl, "reason", RECDB_QSTRING);
 356             str1 = database_get_data(dnsbl, "duration", RECDB_QSTRING);
 357             zone->duration = str1 ? ParseInterval(str1) : 3600;
 358             str1 = database_get_data(dnsbl, "mask", RECDB_QSTRING);
 359             zone->mask = str1 ? strtoul(str1, NULL, 0) : ~0u;
 360             str1 = database_get_data(dnsbl, "debug", RECDB_QSTRING);
 361             zone->debug = str1 ? enabled_string(str1) : 0;
 362             zone->reasons.used = 0;
 363             zone->reasons.size = 0;
 364             zone->reasons.list = NULL;
 365             dict_insert(blacklist_zones, zone->zone, zone);
 366
 367             for (it2 = dict_first(dnsbl); it2; it2 = iter_next(it2)) {
 368                 str1 = GET_RECORD_QSTRING((struct record_data*)(iter_data(it2)));
 369                 if (!str1 || memcmp(iter_key(it2), reason_prefix, strlen(reason_prefix)))
 370                     continue;
 371                 id = strtoul(iter_key(it2) + strlen(reason_prefix), NULL, 0);
 372                 if (id > max_id) {
 373                     log_module(bl_log, LOG_ERROR, "Invalid code for DNSBL %s %s -- only %d responses supported.", iter_key(it), iter_key(it2), max_id);
 374                     continue;
 375                 }
 376                 if (zone->reasons.size < id + 1) {
 377                     zone->reasons.size = id + 1;
 378                     zone->reasons.list = realloc(zone->reasons.list, zone->reasons.size * sizeof(zone->reasons.list[0]));
 379                 }
 380                 zone->reasons.list[id] = (char*)str1;
 381                 if (zone->reasons.used < id + 1)
 382                     zone->reasons.used = id + 1;
 383             }
 384         }
 385     }
 386 }
 387
 388 static void
 389 blacklist_cleanup(void)
 390 {
 391     dict_delete(blacklist_zones);
 392     dict_delete(blacklist_hosts);
 393     dict_delete(blacklist_reasons);
 394 }
 395
 396 int
 397 blacklist_init(void)
 398 {
 399     bl_log = log_register_type("blacklist", "file:blacklist.log");
 400     conf_register_reload(blacklist_conf_read);
 401     reg_new_user_func(blacklist_check_user);
 402     reg_exit_func(blacklist_cleanup);
 403     return 1;
 404 }
 405
 406 int
 407 blacklist_finalize(void)
 408 {
 409     return 1;
 410 }