X-Git-Url: http://git.pk910.de/?a=blobdiff_plain;f=ircd%2FIPcheck.c;h=67b34851cb8fe0bbe4ce905040c4ff1179e81c83;hb=refs%2Fheads%2Fupstream;hp=f867f745d9a86b1cdc24f2e1433deb38eb06e574;hpb=5713fadcc7efab3a4170a465040f6003a8c0f6cc;p=ircu2.10.12-pk.git

diff --git a/ircd/IPcheck.c b/ircd/IPcheck.c
index f867f74..67b3485 100644
--- a/ircd/IPcheck.c
+++ b/ircd/IPcheck.c
@@ -15,140 +15,139 @@
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
- *
- * $Id$
- *
  */
+/** @file
+ * @brief Code to count users connected from particular IP addresses.
+ * @version $Id$
+ */
+#include "config.h"
+
 #include "IPcheck.h"
 #include "client.h"
 #include "ircd.h"
-#include "numnicks.h"
-#include "ircd_alloc.h"
+#include "match.h"
 #include "msg.h"
-#include "s_bsd.h"
-#include "s_debug.h"
-#include "s_user.h"
+#include "ircd_alloc.h"
+#include "ircd_events.h"
+#include "ircd_features.h"
+#include "ircd_log.h"
+#include "ircd_string.h"    /* ircd_ntoa */
+#include "s_debug.h"        /* Debug */
+#include "s_user.h"         /* TARGET_DELAY */
 #include "send.h"
 
-#include <assert.h>
-#include <arpa/inet.h>
-#include <stdio.h>
+/* #include <assert.h> -- Now using assert in ircd_log.h */
 #include <string.h>
 
-#if 0
-#warning Nick collisions are horribly broken in
-#warning this version, and its known to core on
-#warning a whim.  If your even concidering
-#warning running this on something resembling a
-#warning production network, dont bother, its
-#warning not worth your time.  To those of you
-#warning who grabbed the latest CVS version to
-#warning bug test it, thanks, but I recommend
-#warning you stick to previous versions for the
-#warning time being.
-#error --- Broken code ---
-#endif
-
+/** Stores free target information for a particular user. */
 struct IPTargetEntry {
-  int           count;
-  unsigned char targets[MAXTARGETS];
+  unsigned int  count; /**< Number of free targets targets. */
+  unsigned char targets[MAXTARGETS]; /**< Array of recent targets. */
 };
 
+/** Stores recent information about a particular IP address. */
 struct IPRegistryEntry {
-  struct IPRegistryEntry *next;
-  struct IPTargetEntry   *target;
-  unsigned int             addr;
-  time_t                  last_connect;
-  unsigned char            connected;
-  unsigned char            attempts;
+  struct IPRegistryEntry*  next;   /**< Next entry in the hash chain. */
+  struct IPTargetEntry*    target; /**< Recent targets, if any. */
+  struct irc_in_addr       addr;   /**< IP address for this user. */
+  int		           last_connect; /**< Last connection attempt timestamp. */
+  unsigned short           connected; /**< Number of currently connected clients. */
+  unsigned char            attempts; /**< Number of recent connection attempts. */
 };
 
-
-/*
- * Hash table for IPv4 address registry
- *
- * Hash table size must be a power of 2
- * Use 64K hash table to conserve memory
- */
-/*----------------------------------------------------------------------------
- * Compile-time Configuration
- *--------------------------------------------------------------------------*/
+/** Size of hash table (must be a power of two). */
 #define IP_REGISTRY_TABLE_SIZE 0x10000
-#define MASK_16                0xffff
-
-/* We allow 6 connections in 60 seconds */
-#define IPCHECK_CLONE_LIMIT 6
-#define IPCHECK_CLONE_PERIOD 60
-#define IPCHECK_CLONE_DELAY  600
-
-
-/*----------------------------------------------------------------------------
- * Handy Macros
- *--------------------------------------------------------------------------*/
-#define NOW (CurrentTime)
-#define CONNECTED_SINCE(x) (NOW - (x->last_connect))
-
-
-/*----------------------------------------------------------------------------
- * Global Data (ugly!)
- *--------------------------------------------------------------------------*/
-static struct IPRegistryEntry *hashTable[IP_REGISTRY_TABLE_SIZE];
-static struct IPRegistryEntry *freeList = 0;
-
-
-/*----------------------------------------------------------------------------
- * ip_registry_hash:  Create a hash key for an IP registry entry and return
- *                    the value.  (Is unsigned int really a good type to give
- *                    to the IP argument?  Ugly.  This should probably be a
- *                    struct in_addr.  This is asking for trouble.  --ZS)
- *--------------------------------------------------------------------------*/
-static unsigned int ip_registry_hash(unsigned int ip)
+/** Report current time for tracking in IPRegistryEntry::last_connect. */
+#define NOW ((unsigned short)(CurrentTime & 0xffff))
+/** Time from \a x until now, in seconds. */
+#define CONNECTED_SINCE(x) (NOW - (x))
+
+/** Macro for easy access to configured IPcheck clone limit. */
+#define IPCHECK_CLONE_LIMIT feature_int(FEAT_IPCHECK_CLONE_LIMIT)
+/** Macro for easy access to configured IPcheck clone period. */
+#define IPCHECK_CLONE_PERIOD feature_int(FEAT_IPCHECK_CLONE_PERIOD)
+/** Macro for easy access to configured IPcheck clone delay. */
+#define IPCHECK_CLONE_DELAY feature_int(FEAT_IPCHECK_CLONE_DELAY)
+
+/** Hash table for storing IPRegistryEntry entries. */
+static struct IPRegistryEntry* hashTable[IP_REGISTRY_TABLE_SIZE];
+/** List of allocated but unused IPRegistryEntry structs. */
+static struct IPRegistryEntry* freeList;
+/** Periodic timer to look for too-old registry entries. */
+static struct Timer expireTimer;
+
+/** Convert IP addresses to canonical form for comparison.  IPv4
+ * addresses are translated into 6to4 form; IPv6 addresses are left
+ * alone.
+ * @param[out] out Receives canonical format for address.
+ * @param[in] in IP address to canonicalize.
+ */
+static void ip_registry_canonicalize(struct irc_in_addr *out, const struct irc_in_addr *in)
 {
-  return ((ip >> 16) ^ ip) & (IP_REGISTRY_TABLE_SIZE - 1);
+    if (irc_in_addr_is_ipv4(in)) {
+        out->in6_16[0] = htons(0x2002);
+        out->in6_16[1] = in->in6_16[6];
+        out->in6_16[2] = in->in6_16[7];
+        out->in6_16[3] = out->in6_16[4] = out->in6_16[5] = 0;
+        out->in6_16[6] = out->in6_16[7] = 0;
+    } else
+        memcpy(out, in, sizeof(*out));
 }
 
-
-/*----------------------------------------------------------------------------
- * ip_registry_find:  Find a given IP registry entry and return it.
- *--------------------------------------------------------------------------*/
-static struct IPRegistryEntry *ip_registry_find(unsigned int ip) 
+/** Calculate hash value for an IP address.
+ * @param[in] ip Address to hash; must be in canonical form.
+ * @return Hash value for address.
+ */
+static unsigned int ip_registry_hash(const struct irc_in_addr *ip)
 {
-  struct IPRegistryEntry *entry = 0;
+  unsigned int res;
+  /* Only use the first 64 bits of address, since the last 64 bits
+   * tend to be under user control. */
+  res = ip->in6_16[0] ^ ip->in6_16[1] ^ ip->in6_16[2] ^ ip->in6_16[3];
+  return res & (IP_REGISTRY_TABLE_SIZE - 1);
+}
 
-  for (entry = hashTable[ip_registry_hash(ip)]; entry; entry = entry->next) {
-    if (entry->addr == ip)
-      return entry;
+/** Find an IP registry entry if one exists for the IP address.
+ * If \a ip looks like an IPv6 address, only consider the first 64 bits
+ * of the address. Otherwise, only consider the final 32 bits.
+ * @param[in] ip IP address to search for.
+ * @return Matching registry entry, or NULL if none exists.
+ */
+static struct IPRegistryEntry* ip_registry_find(const struct irc_in_addr *ip)
+{
+  struct irc_in_addr canon;
+  struct IPRegistryEntry* entry;
+  ip_registry_canonicalize(&canon, ip);
+  entry = hashTable[ip_registry_hash(&canon)];
+  for ( ; entry; entry = entry->next) {
+    int bits = (canon.in6_16[0] == htons(0x2002)) ? 48 : 64;
+    if (ipmask_check(&canon, &entry->addr, bits))
+      break;
   }
-
-  return NULL;
+  return entry;
 }
 
-
-/*----------------------------------------------------------------------------
- * ip_registry_add:  Add an entry to the IP registry
- *--------------------------------------------------------------------------*/
-static void ip_registry_add(struct IPRegistryEntry *entry) 
+/** Add an IP registry entry to the hash table.
+ * @param[in] entry Registry entry to add.
+ */
+static void ip_registry_add(struct IPRegistryEntry* entry)
 {
-  unsigned int bucket = ip_registry_hash(entry->addr);
-
+  unsigned int bucket = ip_registry_hash(&entry->addr);
   entry->next = hashTable[bucket];
   hashTable[bucket] = entry;
 }
-  
 
-/*----------------------------------------------------------------------------
- * ip_registry_remove:  Remove an entry from the IP registry
- *--------------------------------------------------------------------------*/
-static void ip_registry_remove(struct IPRegistryEntry* entry) 
+/** Remove an IP registry entry from the hash table.
+ * @param[in] entry Registry entry to add.
+ */
+static void ip_registry_remove(struct IPRegistryEntry* entry)
 {
-  unsigned int bucket = ip_registry_hash(entry->addr);
-
+  unsigned int bucket = ip_registry_hash(&entry->addr);
   if (hashTable[bucket] == entry)
     hashTable[bucket] = entry->next;
   else {
-    struct IPRegistryEntry *prev;
-
-    for (prev = hashTable[bucket]; prev; prev = prev->next) {
+    struct IPRegistryEntry* prev = hashTable[bucket];
+    for ( ; prev; prev = prev->next) {
       if (prev->next == entry) {
         prev->next = entry->next;
         break;
@@ -156,109 +155,94 @@ static void ip_registry_remove(struct IPRegistryEntry* entry)
     }
   }
 }
- 
 
-/*----------------------------------------------------------------------------
- * ip_registry_new_entry():  Creates and initializes an IP Registry entry.
- *                           NOW ALSO ADDS IT TO THE LIST! --ZS
- *--------------------------------------------------------------------------*/
-static struct IPRegistryEntry *ip_registry_new_entry(unsigned int addr, int attempt)
+/** Allocate a new IP registry entry.
+ * For members that have a sensible default value, that is used.
+ * @return Newly allocated registry entry.
+ */
+static struct IPRegistryEntry* ip_registry_new_entry(void)
 {
   struct IPRegistryEntry* entry = freeList;
-
   if (entry)
     freeList = entry->next;
   else
-    entry = (struct IPRegistryEntry *)MyMalloc(sizeof(struct IPRegistryEntry));
+    entry = (struct IPRegistryEntry*) MyMalloc(sizeof(struct IPRegistryEntry));
 
   assert(0 != entry);
-
   memset(entry, 0, sizeof(struct IPRegistryEntry));
   entry->last_connect = NOW;     /* Seconds since last connect attempt */
   entry->connected    = 1;       /* connected clients for this IP */
-  entry->attempts     = attempt; /* Number attempts for this IP        */
-  entry->addr         = addr;    /* Entry's IP Address                 */
-
-  ip_registry_add(entry);
-
+  entry->attempts     = 1;       /* Number attempts for this IP */
   return entry;
 }
 
-
-/*----------------------------------------------------------------------------
- * ip_registry_delete_entry:  Frees an entry and adds the structure to a list
- *                            of free structures.  (We should probably reclaim
- *                            the freelist every once in a while!  This is
- *                            potentially a way to DoS the server...  -ZS)
- *--------------------------------------------------------------------------*/
-static void ip_registry_delete_entry(struct IPRegistryEntry *entry)
+/** Deallocate memory for \a entry.
+ * The entry itself is prepended to #freeList.
+ * @param[in] entry IP registry entry to release.
+ */
+static void ip_registry_delete_entry(struct IPRegistryEntry* entry)
 {
   if (entry->target)
     MyFree(entry->target);
-
   entry->next = freeList;
   freeList = entry;
 }
 
-
-/*----------------------------------------------------------------------------
- * ip_registry_update_free_targets:  
- *--------------------------------------------------------------------------*/
-static unsigned int ip_registry_update_free_targets(struct IPRegistryEntry  *entry)
+/** Update free target count for \a entry.
+ * @param[in,out] entry IP registry entry to update.
+ */
+static unsigned int ip_registry_update_free_targets(struct IPRegistryEntry* entry)
 {
   unsigned int free_targets = STARTTARGETS;
 
   if (entry->target) {
-    free_targets = (entry->target->count +
-		    (CONNECTED_SINCE(entry) / TARGET_DELAY));
-
+    free_targets = entry->target->count + (CONNECTED_SINCE(entry->last_connect) / TARGET_DELAY);
     if (free_targets > STARTTARGETS)
       free_targets = STARTTARGETS;
-
     entry->target->count = free_targets;
   }
-
   return free_targets;
 }
 
-
-/*----------------------------------------------------------------------------
- * ip_registry_expire_entry:  expire an IP entry if it needs to be.  If an
- *                            entry isn't expired, then also check the target
- *                            list to see if it needs to be expired.
- *--------------------------------------------------------------------------*/
-static void ip_registry_expire_entry(struct IPRegistryEntry *entry)
+/** Check whether all or part of \a entry needs to be expired.
+ * If the entry is at least 600 seconds stale, free the entire thing.
+ * If it is at least 120 seconds stale, expire its free targets list.
+ * @param[in] entry Registry entry to check for expiration.
+ */
+static void ip_registry_expire_entry(struct IPRegistryEntry* entry)
 {
   /*
    * Don't touch this number, it has statistical significance
    * XXX - blah blah blah
-   * ZS - Just -what- statistical significance does it -have-?
-   * Iso - Noone knows, we've just been told not to touch it.
    */
-  if (CONNECTED_SINCE(entry) > 120 && 0 != entry->target) {
-    MyFree(entry->target);
-    entry->target = 0;
-  }
-  if (CONNECTED_SINCE(entry) > 600) {
+  if (CONNECTED_SINCE(entry->last_connect) > 600) {
+    /*
+     * expired
+     */
+    Debug((DEBUG_DNS, "IPcheck expiring registry for %s (no clients connected).", ircd_ntoa(&entry->addr)));
     ip_registry_remove(entry);
     ip_registry_delete_entry(entry);
   }
+  else if (CONNECTED_SINCE(entry->last_connect) > 120 && 0 != entry->target) {
+    /*
+     * Expire storage of targets
+     */
+    MyFree(entry->target);
+    entry->target = 0;
+  }
 }
 
-
-/*----------------------------------------------------------------------------
- * ip_registry_expire:  Expire all of the needed entries in the hash table
- *--------------------------------------------------------------------------*/
-void ip_registry_expire(void)
+/** Periodic timer callback to check for expired registry entries.
+ * @param[in] ev Timer event (ignored).
+ */
+static void ip_registry_expire(struct Event* ev)
 {
-  struct IPRegistryEntry *entry;
-  struct IPRegistryEntry *entry_next;
-  static time_t   next_expire = 0;
   int i;
+  struct IPRegistryEntry* entry;
+  struct IPRegistryEntry* entry_next;
 
-  /* Only do this if we're ready to */
-  if (next_expire >= CurrentTime)
-    return;
+  assert(ET_EXPIRE == ev_type(ev));
+  assert(0 != ev_timer(ev));
 
   for (i = 0; i < IP_REGISTRY_TABLE_SIZE; ++i) {
     for (entry = hashTable[i]; entry; entry = entry_next) {
@@ -267,331 +251,322 @@ void ip_registry_expire(void)
         ip_registry_expire_entry(entry);
     }
   }
-
-  next_expire = CurrentTime + 60;
 }
 
+/** Initialize the IPcheck subsystem. */
+void IPcheck_init(void)
+{
+  timer_add(timer_init(&expireTimer), ip_registry_expire, 0, TT_PERIODIC, 60);
+}
 
-/*----------------------------------------------------------------------------
- *
- * Event:
- *   A new connection was accept()-ed with IP number `cptr->ip.s_addr'.
- *
- * Action:
- *   Update the IPcheck registry.
- *   Return:
- *     1 : You're allowed to connect.
- *     0 : You're not allowed to connect.
- *
- * Throttling:
- *
- * A connection should be rejected when a connection from the same IP
- * number was received IPCHECK_CLONE_LIMIT times before this connect
- * attempt, with reconnect intervals of IPCHECK_CLONE_PERIOD seconds
- * or less.
- *
- * Free target inheritance:
- *
- * When the client is accepted, then the number of Free Targets
- * of the cptr is set to the value stored in the found IPregistry
- * structure, or left at STARTTARGETS.  This can be done by changing
- * cptr->nexttarget to be `now - (TARGET_DELAY * (FREE_TARGETS - 1))',
- * where FREE_TARGETS may range from 0 till STARTTARGETS.
- *--------------------------------------------------------------------------*/
-int ip_registry_check_local(unsigned int addr, time_t *next_target_out)
+/** Check whether a new connection from a local client should be allowed.
+ * A connection is rejected if someone from the "same" address (see
+ * ip_registry_find()) connects IPCHECK_CLONE_LIMIT times, each time
+ * separated by no more than IPCHECK_CLONE_PERIOD seconds.
+ * @param[in] addr Address of client.
+ * @param[out] next_target_out Receives time to grant another free target.
+ * @return Non-zero if the connection is permitted, zero if denied.
+ */
+int ip_registry_check_local(const struct irc_in_addr *addr, time_t* next_target_out)
 {
-  struct IPRegistryEntry *entry        = ip_registry_find(addr);
+  struct IPRegistryEntry* entry = ip_registry_find(addr);
   unsigned int free_targets = STARTTARGETS;
- 
-  assert(0 != next_target_out);
 
-  /* If they've never connected before, let them on */
   if (0 == entry) {
-    Debug((DEBUG_DEBUG,"IPcheck: Local user allowed - unseen"));
-    entry = ip_registry_new_entry(addr, 1);
+    entry       = ip_registry_new_entry();
+    ip_registry_canonicalize(&entry->addr, addr);
+    ip_registry_add(entry);
+    Debug((DEBUG_DNS, "IPcheck added new registry for local connection from %s.", ircd_ntoa(&entry->addr)));
     return 1;
   }
-  
-  /* Keep track of how many people have connected */
-  entry->connected++;
-
-  /* Do not allow more than 250 connects from a single IP, EVER. */
-  if (250 <= entry->connected) {
-    Debug((DEBUG_DEBUG,"IPcheck: Local user disallowed - Too many connections"));
+  /* Note that this also counts server connects.
+   * It is hard and not interesting, to change that.
+   * Refuse connection if it would overflow the counter.
+   */
+  if (0 == ++entry->connected)
+  {
     entry->connected--;
+    Debug((DEBUG_DNS, "IPcheck refusing local connection from %s: counter overflow.", ircd_ntoa(&entry->addr)));
     return 0;
   }
 
-  /* If our threshhold has elapsed, reset the counter so we don't throttle,
-   * IPCHECK_CLONE_LIMIT connections every IPCHECK_CLONE_PERIOD
-   */
-  if (CONNECTED_SINCE(entry) > IPCHECK_CLONE_PERIOD) {
+  if (CONNECTED_SINCE(entry->last_connect) > IPCHECK_CLONE_PERIOD)
     entry->attempts = 0;
-    entry->last_connect = NOW;
-  }
-
-  /* Count the number of recent attempts */ 
-  entry->attempts++;
-  
-  if (250 <= entry->attempts)
-    --entry->attempts;  /* Disallow overflow */
-
 
   free_targets = ip_registry_update_free_targets(entry);
+  entry->last_connect = NOW;
 
-  /* Have they connected less than IPCHECK_CLONE_LIMIT times && next_target_out */
-  if (entry->attempts < IPCHECK_CLONE_LIMIT && next_target_out) {
+  if (0 == ++entry->attempts)   /* Check for overflow */
+    --entry->attempts;
+
+  if (entry->attempts < IPCHECK_CLONE_LIMIT) {
+    if (next_target_out)
       *next_target_out = CurrentTime - (TARGET_DELAY * free_targets - 1);
-      entry->last_connect = NOW;
-      Debug((DEBUG_DEBUG,"IPcheck: Local user allowed"));
-      return 1;
   }
-  
-  /* If the server is younger than IPCHECK_CLONE_DELAY then the person
-   * is allowed on.
-   */
-  if ((CurrentTime - me.since) < IPCHECK_CLONE_DELAY) {
-    Debug((DEBUG_DEBUG,"IPcheck: Local user allowed during server startup"));
-    return 1;
+  else if ((CurrentTime - cli_since(&me)) > IPCHECK_CLONE_DELAY) {
+    /*
+     * Don't refuse connection when we just rebooted the server
+     */
+#ifndef NOTHROTTLE
+    assert(entry->connected > 0);
+    --entry->connected;
+    Debug((DEBUG_DNS, "IPcheck refusing local connection from %s: too fast.", ircd_ntoa(&entry->addr)));
+    return 0;
+#endif
   }
-  
-  /* Otherwise they're throttled */
-  entry->connected--;
-  Debug((DEBUG_DEBUG,"IPcheck: Throttling local user"));
-  return 0;
+  Debug((DEBUG_DNS, "IPcheck accepting local connection from %s.", ircd_ntoa(&entry->addr)));
+  return 1;
 }
 
-/*
- * Add someone to the ip registry without throttling them.
- * This is used for server connections.
+/** Check whether a connection from a remote client should be allowed.
+ * This is much more relaxed than ip_registry_check_local(): The only
+ * cause for rejection is when the IPRegistryEntry::connected counter
+ * would overflow.
+ * @param[in] cptr Client that has connected.
+ * @param[in] is_burst Non-zero if client was introduced during a burst.
+ * @return Non-zero if the client should be accepted, zero if they must be killed.
  */
-void ip_registry_add_local(unsigned int addr)
+int ip_registry_check_remote(struct Client* cptr, int is_burst)
 {
-  struct IPRegistryEntry *entry        = ip_registry_find(addr);
- 
-  /* If they've never connected before, let them on */
-  if (0 == entry) {
-    Debug((DEBUG_DEBUG,"IPcheck: Local user allowed - unseen"));
-    entry = ip_registry_new_entry(addr, 1);
-    return;
-  }
-  
-  /* Keep track of how many people have connected */
-  entry->connected++;
-
-  assert(250 <= entry->connected);
-
-  return;
-}
-
-/*----------------------------------------------------------------------------
- * ip_registry_remote_connect
- *
- * Does anything that needs to be done once we actually have a client
- * structure to play with on a remote connection.
- * returns:
- *  1 - allowed to connect
- *  0 - disallowed.
- *--------------------------------------------------------------------------*/
-int ip_registry_remote_connect(struct Client *cptr)
-{
-  struct IPRegistryEntry *entry        = ip_registry_find(cptr->ip.s_addr);
-  assert(0 != cptr);
+  struct IPRegistryEntry* entry;
 
-  /* If they've never connected before, let them on */
+  /*
+   * Mark that we did add/update an IPregistry entry
+   */
+  SetIPChecked(cptr);
+  if (!irc_in_addr_valid(&cli_ip(cptr))) {
+    Debug((DEBUG_DNS, "IPcheck accepting remote connection from invalid %s.", ircd_ntoa(&cli_ip(cptr))));
+    return 1;
+  }
+  entry = ip_registry_find(&cli_ip(cptr));
   if (0 == entry) {
-    entry = ip_registry_new_entry(cptr->ip.s_addr, 1);
-    SetIPChecked(cptr);
-    Debug((DEBUG_DEBUG,"IPcheck: First remote connection.  connected=%i",entry->connected));
+    entry = ip_registry_new_entry();
+    ip_registry_canonicalize(&entry->addr, &cli_ip(cptr));
+    if (is_burst)
+      entry->attempts = 0;
+    ip_registry_add(entry);
+    Debug((DEBUG_DNS, "IPcheck added new registry for remote connection from %s.", ircd_ntoa(&entry->addr)));
     return 1;
   }
-  
-  /* Keep track of how many people have connected */
-  entry->connected++;
-  SetIPChecked(cptr);
-
-  /* Do not allow more than 250 connections from one IP.
-   * This can happen by having 128 clients on one server, and 128 on another
-   * and then the servers joining after a netsplit
-   */ 
-  if (250 <= entry->connected) {
-    sendto_ops("IPcheck Ghost! [%s]",inet_ntoa(cptr->ip));
-    Debug((DEBUG_DEBUG,"IPcheck: Too many connected from IP: %i",entry->connected));
+  /* Avoid overflowing the connection counter. */
+  if (0 == ++entry->connected) {
+    Debug((DEBUG_DNS, "IPcheck refusing remote connection from %s: counter overflow.", ircd_ntoa(&entry->addr)));
     return 0;
   }
-  
-  Debug((DEBUG_DEBUG,"IPcheck: %i people connected",entry->connected));
-  
-  /* They are allowed to connect */
+  if (CONNECTED_SINCE(entry->last_connect) > IPCHECK_CLONE_PERIOD)
+    entry->attempts = 0;
+  if (!is_burst) {
+    if (0 == ++entry->attempts) {
+      /*
+       * Check for overflow
+       */
+      --entry->attempts;
+    }
+    ip_registry_update_free_targets(entry);
+    entry->last_connect = NOW;
+  }
+  Debug((DEBUG_DNS, "IPcheck counting remote connection from %s.", ircd_ntoa(&entry->addr)));
   return 1;
 }
 
-/*----------------------------------------------------------------------------
- * IPcheck_connect_succeeded
- *
- * Event:
- *   A client succeeded to finish the registration.
- *
- * Finish IPcheck registration of a successfully, locally connected client.
- *--------------------------------------------------------------------------*/
+/** Handle a client being rejected during connection through no fault
+ * of their own.  This "undoes" the effect of ip_registry_check_local()
+ * so the client's address is not penalized for the failure.
+ * @param[in] addr Address of rejected client.
+ * @param[in] disconnect If true, also count the client as disconnecting.
+ */
+void ip_registry_connect_fail(const struct irc_in_addr *addr, int disconnect)
+{
+  struct IPRegistryEntry* entry = ip_registry_find(addr);
+  if (entry) {
+    if (0 == --entry->attempts) {
+      Debug((DEBUG_DNS, "IPcheck noting local connection failure for %s.", ircd_ntoa(&entry->addr)));
+      ++entry->attempts;
+    }
+    if (disconnect) {
+      assert(entry->connected > 0);
+      entry->connected--;
+    }
+  }
+}
+
+/** Handle a client that has successfully connected.
+ * This copies free target information to \a cptr from his address's
+ * registry entry and sends him a NOTICE describing the parameters for
+ * the entry.
+ * @param[in,out] cptr Client that has successfully connected.
+ */
 void ip_registry_connect_succeeded(struct Client *cptr)
 {
+  const char*             tr    = "";
   unsigned int free_targets     = STARTTARGETS;
-  struct IPRegistryEntry *entry;
-
-  assert(cptr);
-
-  entry = ip_registry_find(cptr->ip.s_addr);
-
+  struct IPRegistryEntry* entry = ip_registry_find(&cli_ip(cptr));
 
   assert(entry);
-
   if (entry->target) {
-    memcpy(cptr->targets, entry->target->targets, MAXTARGETS);
+    memcpy(cli_targets(cptr), entry->target->targets, MAXTARGETS);
     free_targets = entry->target->count;
+    tr = " tr";
   }
-
-  sendcmdto_one(&me, CMD_NOTICE, cptr, "%C :connected %u attempts %u/%u free targets %u/%u%s"
-  		" IPcheck: %s",
+  Debug((DEBUG_DNS, "IPcheck noting local connection success for %s.", ircd_ntoa(&entry->addr)));
+  sendcmdto_one(&me, CMD_NOTICE, cptr, "%C :on %u ca %u(%u) ft %u(%u)%s",
 		cptr, entry->connected, entry->attempts, IPCHECK_CLONE_LIMIT,
-		free_targets, STARTTARGETS, 
-		((entry->target) ? " [Inherited Targets]" : ""), 
-		((CurrentTime - me.since) < IPCHECK_CLONE_DELAY) ? "Disabled" : "Enabled");
-		
-  SetIPChecked(cptr);
+		free_targets, STARTTARGETS, tr);
 }
 
-
-/*----------------------------------------------------------------------------
- * IPcheck_disconnect
- *
- * Event:
- *   A local client disconnected.
- *
- * Action:
- *   Update the IPcheck registry.
- *   Remove all expired IPregistry structures from the hash bucket
- *     that belongs to this clients IP number.
- *--------------------------------------------------------------------------*/
-void ip_registry_local_disconnect(struct Client *cptr)
+/** Handle a client that decided to disconnect (or was killed after
+ * completing his connection).  This updates the free target
+ * information for his IP registry entry.
+ * @param[in] cptr Client that has exited.
+ */
+void ip_registry_disconnect(struct Client *cptr)
 {
-  struct IPRegistryEntry *entry;
-  unsigned int free_targets;
-
-  assert(0 != cptr);
-
-  entry = ip_registry_find(cptr->ip.s_addr);
-
-  Debug((DEBUG_DEBUG,"IPcheck: Local Disconnect"));
-  	
-  assert(IsIPChecked(cptr));
-  
+  struct IPRegistryEntry* entry = ip_registry_find(&cli_ip(cptr));
+  if (!irc_in_addr_valid(&cli_ip(cptr))) {
+    Debug((DEBUG_DNS, "IPcheck noting dicconnect from invalid %s.", ircd_ntoa(&cli_ip(cptr))));
+    return;
+  }
   assert(entry);
-
   assert(entry->connected > 0);
-  
-  if (entry->connected > 0) {
-    entry->connected--;
-  }
-
+  Debug((DEBUG_DNS, "IPcheck noting disconnect from %s.", ircd_ntoa(&entry->addr)));
   /*
-   * If this was the last one, set `last_connect' to disconnect time
-   * (used for expiration)   Note that we reset attempts here as well if our
-   * threshhold hasn't been crossed.
+   * If this was the last one, set `last_connect' to disconnect time (used for expiration)
    */
-  if (0 == entry->connected) {
+  if (0 == --entry->connected) {
+    if (CONNECTED_SINCE(entry->last_connect) > IPCHECK_CLONE_LIMIT * IPCHECK_CLONE_PERIOD) {
+      /*
+       * Otherwise we'd penalize for this old value if the client reconnects within 20 seconds
+       */
+      entry->attempts = 0;
+    }
     ip_registry_update_free_targets(entry);
     entry->last_connect = NOW;
   }
-  
-  assert(MyConnect(cptr));
-
-  if (0 == entry->target) {
-    entry->target = (struct IPTargetEntry *)MyMalloc(sizeof(struct IPTargetEntry));
+  if (MyConnect(cptr)) {
+    unsigned int free_targets;
+    /*
+     * Copy the clients targets
+     */
+    if (0 == entry->target) {
+      entry->target = (struct IPTargetEntry*) MyMalloc(sizeof(struct IPTargetEntry));
+      entry->target->count = STARTTARGETS;
+    }
     assert(0 != entry->target);
-    entry->target->count = STARTTARGETS;
-  }
-  memcpy(entry->target->targets, cptr->targets, MAXTARGETS);
-
-  /*
-   * This calculation can be pretty unfair towards large multi-user hosts,
-   * but there is "nothing" we can do without also allowing spam bots to
-   * send more messages or by drastically increasing the ammount of memory
-   * used in the IPregistry.
-   *
-   * The problem is that when a client disconnects, leaving no free targets,
-   * then the next client from that IP number has to pay for it (getting no
-   * free targets).  But ALSO the next client, and the next client, and the
-   * next client etc - until another client disconnects that DOES leave free
-   * targets.  The reason for this is that if there are 10 SPAM bots, and
-   * they all disconnect at once, then they ALL should get no free targets
-   * when reconnecting.  We'd need to store an entry per client (instead of
-   * per IP number) to avoid this.  
-   */
-  if (cptr->nexttarget < CurrentTime)
-    free_targets = (CurrentTime - cptr->nexttarget) / TARGET_DELAY + 1;
-  else
-    free_targets = 0;
 
-  /* Add bonus, if you've been connected for more than 10 minutes you
-   * get a free target every TARGET_DELAY seconds.
-   * this is pretty fuzzy, but it will help in some cases. 
-   */
-  if ((CurrentTime - cptr->firsttime) > 600)
-    free_targets += (CurrentTime - cptr->firsttime - 600) / TARGET_DELAY;
+    memcpy(entry->target->targets, cli_targets(cptr), MAXTARGETS);
+    /*
+     * This calculation can be pretty unfair towards large multi-user hosts, but
+     * there is "nothing" we can do without also allowing spam bots to send more
+     * messages or by drastically increasing the amount of memory used in the IPregistry.
+     *
+     * The problem is that when a client disconnects, leaving no free targets, then
+     * the next client from that IP number has to pay for it (getting no free targets).
+     * But ALSO the next client, and the next client, and the next client etc - until
+     * another client disconnects that DOES leave free targets.  The reason for this
+     * is that if there are 10 SPAM bots, and they all disconnect at once, then they
+     * ALL should get no free targets when reconnecting.  We'd need to store an entry
+     * per client (instead of per IP number) to avoid this.
+     */
+    if (cli_nexttarget(cptr) < CurrentTime) {
+        /*
+         * Number of free targets
+         */
+      free_targets = (CurrentTime - cli_nexttarget(cptr)) / TARGET_DELAY + 1;
+    }
+    else
+      free_targets = 0;
+    /*
+     * Add bonus, this is pretty fuzzy, but it will help in some cases.
+     */
+    if ((CurrentTime - cli_firsttime(cptr)) > 600)
+      /*
+       * Was longer then 10 minutes online?
+       */
+      free_targets += (CurrentTime - cli_firsttime(cptr) - 600) / TARGET_DELAY;
+    /*
+     * Finally, store smallest value for Judgment Day
+     */
+    if (free_targets < entry->target->count)
+      entry->target->count = free_targets;
+  }
+}
 
-  /* Finally, store smallest value for Judgement Day */
-  if (free_targets < entry->target->count)
-    entry->target->count = free_targets;
-  
+/** Find number of clients from a particular IP address.
+ * @param[in] addr Address to look up.
+ * @return Number of clients known to be connected from that address.
+ */
+int ip_registry_count(const struct irc_in_addr *addr)
+{
+  struct IPRegistryEntry* entry = ip_registry_find(addr);
+  return (entry) ? entry->connected : 0;
 }
 
-/*----------------------------------------------------------------------------
- * ip_registry_remote_disconnect
- *
- * Event:
- *   A remote client disconnected.
- *
- * Action:
- *   Update the IPcheck registry.
- *   Remove all expired IPregistry structures from the hash bucket
- *     that belongs to this clients IP number.
- *--------------------------------------------------------------------------*/
-void ip_registry_remote_disconnect(struct Client *cptr)
+/** Check whether a client is allowed to connect locally.
+ * @param[in] a Address of client.
+ * @param[out] next_target_out Receives time to grant another free target.
+ * @return Non-zero if the connection is permitted, zero if denied.
+ */
+int IPcheck_local_connect(const struct irc_in_addr *a, time_t* next_target_out)
 {
-  struct IPRegistryEntry *entry;
+  assert(0 != next_target_out);
+  return ip_registry_check_local(a, next_target_out);
+}
 
+/** Check whether a client is allowed to connect remotely.
+ * @param[in] cptr Client that has connected.
+ * @param[in] is_burst Non-zero if client was introduced during a burst.
+ * @return Non-zero if the client should be accepted, zero if they must be killed.
+ */
+int IPcheck_remote_connect(struct Client *cptr, int is_burst)
+{
   assert(0 != cptr);
+  assert(!IsIPChecked(cptr));
+  return ip_registry_check_remote(cptr, is_burst);
+}
 
-  entry = ip_registry_find(cptr->ip.s_addr);
-  
-  assert(entry);
-  
-  assert(entry->connected > 0);
-  Debug((DEBUG_DEBUG,"IPcheck: Remote Disconnect"));
+/** Handle a client being rejected during connection through no fault
+ * of their own.  This "undoes" the effect of ip_registry_check_local()
+ * so the client's address is not penalized for the failure.
+ * @param[in] cptr Client who has been rejected.
+ * @param[in] disconnect If true, also count the client as disconnecting.
+ */
+void IPcheck_connect_fail(const struct Client *cptr, int disconnect)
+{
+  assert(IsIPChecked(cptr));
+  ip_registry_connect_fail(&cli_ip(cptr), disconnect);
+}
 
-  if (entry->connected > 0) {
-    entry->connected--;
-  }
+/** Handle a client that has successfully connected.
+ * This copies free target information to \a cptr from his address's
+ * registry entry and sends him a NOTICE describing the parameters for
+ * the entry.
+ * @param[in,out] cptr Client that has successfully connected.
+ */
+void IPcheck_connect_succeeded(struct Client *cptr)
+{
+  assert(0 != cptr);
+  assert(IsIPChecked(cptr));
+  ip_registry_connect_succeeded(cptr);
+}
 
-  /*
-   * If this was the last one, set `last_connect' to disconnect time
-   * (used for expiration)   Note that we reset attempts here as well if our
-   * threshhold hasn't been crossed.
-   */
-  if (0 == entry->connected) {
-    ip_registry_update_free_targets(entry);
-    entry->last_connect=NOW;
-  }
+/** Handle a client that decided to disconnect (or was killed after
+ * completing his connection).  This updates the free target
+ * information for his IP registry entry.
+ * @param[in] cptr Client that has exited.
+ */
+void IPcheck_disconnect(struct Client *cptr)
+{
+  assert(0 != cptr);
+  assert(IsIPChecked(cptr));
+  ip_registry_disconnect(cptr);
 }
 
-/*----------------------------------------------------------------------------
- * IPcheck_nr
- *
- * Returns number of clients with the same IP number
- *--------------------------------------------------------------------------*/
-int ip_registry_count(unsigned int addr)
+/** Find number of clones of a client.
+ * @param[in] cptr Client whose address to look up.
+ * @return Number of clients known to be connected from that address.
+ */
+unsigned short IPcheck_nr(struct Client *cptr)
 {
-  struct IPRegistryEntry *entry = ip_registry_find(addr);
-  return (entry) ? entry->connected : 0;
+  assert(0 != cptr);
+  return ip_registry_count(&cli_ip(cptr));
 }