Prohibit same +A and +U pass; fix IAuth crash (#1193808), invite

[ircu2.10.12-pk.git] / ircd / channel.c

/*
 * IRC - Internet Relay Chat, ircd/channel.c
 * Copyright (C) 1990 Jarkko Oikarinen and
 *                    University of Oulu, Co Center
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 1, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * 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.
 */
/** @file
 * @brief Channel management and maintenance
 * @version $Id$
 */
#include "config.h"

#include "channel.h"
#include "client.h"
#include "destruct_event.h"
#include "hash.h"
#include "ircd.h"
#include "ircd_alloc.h"
#include "ircd_chattr.h"
#include "ircd_defs.h"
#include "ircd_features.h"
#include "ircd_log.h"
#include "ircd_reply.h"
#include "ircd_snprintf.h"
#include "ircd_string.h"
#include "list.h"
#include "match.h"
#include "msg.h"
#include "msgq.h"
#include "numeric.h"
#include "numnicks.h"
#include "querycmds.h"
#include "s_bsd.h"
#include "s_conf.h"
#include "s_debug.h"
#include "s_misc.h"
#include "s_user.h"
#include "send.h"
#include "struct.h"
#include "sys.h"
#include "whowas.h"

/* #include <assert.h> -- Now using assert in ircd_log.h */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/** Linked list containing the full list of all channels */
struct Channel* GlobalChannelList = 0;

/** Number of struct Membership*'s allocated */
static unsigned int membershipAllocCount;
/** Freelist for struct Membership*'s */
static struct Membership* membershipFreeList;
/** Freelist for struct Ban*'s */
static struct Ban* free_bans;

#if !defined(NDEBUG)
/** return the length (>=0) of a chain of links.
 * @param lp    pointer to the start of the linked list
 * @return the number of items in the list
 */
static int list_length(struct SLink *lp)
{
  int count = 0;

  for (; lp; lp = lp->next)
    ++count;
  return count;
}
#endif

/** Set the mask for a ban, checking for IP masks.
 * @param[in,out] ban Ban structure to modify.
 * @param[in] banstr Mask to ban.
 */
static void
set_ban_mask(struct Ban *ban, const char *banstr)
{
  char *sep;
  MyFree(ban->banstr);
  if (!banstr)
    return;
  DupString(ban->banstr, banstr);
  sep = strrchr(banstr, '@');
  if (sep) {
    ban->nu_len = sep - banstr;
    if (ipmask_parse(sep + 1, &ban->address, &ban->addrbits))
      ban->flags |= BAN_IPMASK;
  }
}

/** Allocate a new Ban structure.
 * @param[in] banstr Ban mask to use.
 * @return Newly allocated ban.
 */
struct Ban *
make_ban(const char *banstr)
{
  struct Ban *ban;
  if (free_bans) {
    ban = free_bans;
    free_bans = free_bans->next;
  }
  else if (!(ban = MyMalloc(sizeof(*ban))))
    return NULL;
  memset(ban, 0, sizeof(*ban));
  set_ban_mask(ban, banstr);
  return ban;
}

/** Deallocate a ban structure.
 * @param[in] ban Ban to deallocate.
 */
void
free_ban(struct Ban *ban)
{
  MyFree(ban->who);
  MyFree(ban->banstr);
  ban->next = free_bans;
  free_bans = ban;
}

/** return the struct Membership* that represents a client on a channel
 * This function finds a struct Membership* which holds the state about
 * a client on a specific channel.  The code is smart enough to iterate
 * over the channels a user is in, or the users in a channel to find the
 * user depending on which is likely to be more efficient.
 *
 * @param chptr pointer to the channel struct
 * @param cptr pointer to the client struct
 *
 * @returns pointer to the struct Membership representing this client on 
 *          this channel.  Returns NULL if the client is not on the channel.
 *          Returns NULL if the client is actually a server.
 * @see find_channel_member()
 */
struct Membership* find_member_link(struct Channel* chptr, const struct Client* cptr)
{
  struct Membership *m;
  assert(0 != cptr);
  assert(0 != chptr);
  
  /* Servers don't have member links */
  if (IsServer(cptr)||IsMe(cptr))
     return 0;
  
  /* +k users are typically on a LOT of channels.  So we iterate over who
   * is in the channel.  X/W are +k and are in about 5800 channels each.
   * however there are typically no more than 1000 people in a channel
   * at a time.
   */
  if (IsChannelService(cptr)) {
    m = chptr->members;
    while (m) {
      assert(m->channel == chptr);
      if (m->user == cptr)
        return m;
      m = m->next_member;
    }
  }
  /* Users on the other hand aren't allowed on more than 15 channels.  50%
   * of users that are on channels are on 2 or less, 95% are on 7 or less,
   * and 99% are on 10 or less.
   */
  else {
   m = (cli_user(cptr))->channel;
   while (m) {
     assert(m->user == cptr);
     if (m->channel == chptr)
       return m;
     m = m->next_channel;
   }
  }
  return 0;
}

/** Find the client structure for a nick name (user) 
 * Find the client structure for a nick name (user)
 * using history mechanism if necessary. If the client is not found, an error
 * message (NO SUCH NICK) is generated. If the client was found
 * through the history, chasing will be 1 and otherwise 0.
 *
 * This function was used extensively in the P09 days, and since we now have
 * numeric nicks is no longer quite as important.
 *
 * @param sptr  Pointer to the client that has requested the search
 * @param user  a string representing the client to be found
 * @param chasing a variable set to 0 if the user was found directly, 
 *              1 otherwise
 * @returns a pointer the client, or NULL if the client wasn't found.
 */
struct Client* find_chasing(struct Client* sptr, const char* user, int* chasing)
{
  struct Client* who = FindClient(user);

  if (chasing)
    *chasing = 0;
  if (who)
    return who;

  if (!(who = get_history(user, feature_int(FEAT_KILLCHASETIMELIMIT)))) {
    send_reply(sptr, ERR_NOSUCHNICK, user);
    return 0;
  }
  if (chasing)
    *chasing = 1;
  return who;
}

/** Decrement the count of users, and free if empty.
 * Subtract one user from channel i (and free channel * block, if channel 
 * became empty).
 *
 * @param chptr The channel to subtract one from.
 *
 * @returns true  (1) if channel still has members.
 *          false (0) if the channel is now empty.
 */
int sub1_from_channel(struct Channel* chptr)
{
  if (chptr->users > 1)         /* Can be 0, called for an empty channel too */
  {
    assert(0 != chptr->members);
    --chptr->users;
    return 1;
  }

  chptr->users = 0;

  /*
   * Also channels without Apass set need to be kept alive,
   * otherwise Bad Guys(tm) would be able to takeover
   * existing channels too easily, and then set an Apass!
   * However, if a channel without Apass becomes empty
   * then we try to be kind to them and remove possible
   * limiting modes.
   */
  chptr->mode.mode &= ~MODE_INVITEONLY;
  chptr->mode.limit = 0;
  /*
   * We do NOT reset a possible key or bans because when
   * the 'channel owners' can't get in because of a key
   * or ban then apparently there was a fight/takeover
   * on the channel and we want them to contact IRC opers
   * who then will educate them on the use of Apass/upass.
   */

  if (!chptr->mode.apass[0])         /* If no Apass, destroy now. */
    destruct_channel(chptr);
  else if (TStime() - chptr->creationtime < 172800)     /* Channel younger than 48 hours? */
    schedule_destruct_event_1m(chptr);          /* Get rid of it in approximately 4-5 minutes */
  else
    schedule_destruct_event_48h(chptr);         /* Get rid of it in approximately 48 hours */

  return 0;
}

/** Destroy an empty channel
 * This function destroys an empty channel, removing it from hashtables,
 * and removing any resources it may have consumed.
 *
 * @param chptr The channel to destroy
 *
 * @returns 0 (success)
 *
 * FIXME: Change to return void, this function never fails.
 */
int destruct_channel(struct Channel* chptr)
{
  struct Ban *ban, *next;

  assert(0 == chptr->members);

  /*
   * Now, find all invite links from channel structure
   */
  while (chptr->invites)
    del_invite(chptr->invites->value.cptr, chptr);

  for (ban = chptr->banlist; ban; ban = next)
  {
    next = ban->next;
    free_ban(ban);
  }
  if (chptr->prev)
    chptr->prev->next = chptr->next;
  else
    GlobalChannelList = chptr->next;
  if (chptr->next)
    chptr->next->prev = chptr->prev;
  hRemChannel(chptr);
  --UserStats.channels;
  /*
   * make sure that channel actually got removed from hash table
   */
  assert(chptr->hnext == chptr);
  MyFree(chptr);
  return 0;
}

/** returns Membership * if a person is joined and not a zombie
 * @param cptr Client
 * @param chptr Channel
 * @returns pointer to the client's struct Membership * on the channel if that
 *          user is a full member of the channel, or NULL otherwise.
 *
 * @see find_member_link()
 */
struct Membership* find_channel_member(struct Client* cptr, struct Channel* chptr)
{
  struct Membership* member;
  assert(0 != chptr);

  member = find_member_link(chptr, cptr);
  return (member && !IsZombie(member)) ? member : 0;
}

/** Searches for a ban from a ban list that matches a user.
 * @param[in] cptr The client to test.
 * @param[in] banlist The list of bans to test.
 * @return Pointer to a matching ban, or NULL if none exit.
 */
struct Ban *find_ban(struct Client *cptr, struct Ban *banlist)
{
  char        nu[NICKLEN + USERLEN + 2];
  char        tmphost[HOSTLEN + 1];
  char       *sr;
  struct Ban *found;

  /* Build nick!user and alternate host names. */
  ircd_snprintf(0, nu, sizeof(nu), "%s!%s",
                cli_name(cptr), cli_user(cptr)->username);
  if (!IsAccount(cptr))
    sr = NULL;
  else if (HasHiddenHost(cptr))
    sr = cli_user(cptr)->realhost;
  else
  {
    ircd_snprintf(0, tmphost, HOSTLEN, "%s.%s",
                  cli_user(cptr)->account, feature_str(FEAT_HIDDEN_HOST));
    sr = tmphost;
  }

  /* Walk through ban list. */
  for (found = NULL; banlist; banlist = banlist->next) {
    int res;
    /* If we have found a positive ban already, only consider exceptions. */
    if (found && !(banlist->flags & BAN_EXCEPTION))
      continue;
    /* Compare nick!user portion of ban. */
    banlist->banstr[banlist->nu_len] = '\0';
    res = match(banlist->banstr, nu);
    banlist->banstr[banlist->nu_len] = '@';
    if (res)
      continue;
    /* Compare host portion of ban. */
    if (!((banlist->flags & BAN_IPMASK)
         && ipmask_check(&cli_ip(cptr), &banlist->address, banlist->addrbits))
        && match(banlist->banstr + banlist->nu_len + 1, cli_user(cptr)->host)
        && !(sr && match(banlist->banstr + banlist->nu_len + 1, sr) == 0))
      continue;
    /* If an exception matches, no ban can match. */
    if (banlist->flags & BAN_EXCEPTION)
      return NULL;
    /* Otherwise, remember this ban but keep searching for an exception. */
    found = banlist;
  }
  return found;
}

/**
 * This function returns true if the user is banned on the said channel.
 * This function will check the ban cache if applicable, otherwise will
 * do the comparisons and cache the result.
 *
 * @param[in] member The Membership to test for banned-ness.
 * @return Non-zero if the member is banned, zero if not.
 */
static int is_banned(struct Membership* member)
{
  if (IsBanValid(member))
    return IsBanned(member);

  SetBanValid(member);
  if (find_ban(member->user, member->channel->banlist)) {
    SetBanned(member);
    return 1;
  } else {
    ClearBanned(member);
    return 0;
  }
}

/** add a user to a channel.
 * adds a user to a channel by adding another link to the channels member
 * chain.
 *
 * @param chptr The channel to add to.
 * @param who   The user to add.
 * @param flags The flags the user gets initially.
 * @param oplevel The oplevel the user starts with.
 */
void add_user_to_channel(struct Channel* chptr, struct Client* who,
                                unsigned int flags, int oplevel)
{
  assert(0 != chptr);
  assert(0 != who);

  if (cli_user(who)) {
   
    struct Membership* member = membershipFreeList;
    if (member)
      membershipFreeList = member->next_member;
    else {
      member = (struct Membership*) MyMalloc(sizeof(struct Membership));
      ++membershipAllocCount;
    }

    assert(0 != member);
    member->user         = who;
    member->channel      = chptr;
    member->status       = flags;
    member->oplevel      = oplevel;

    member->next_member  = chptr->members;
    if (member->next_member)
      member->next_member->prev_member = member;
    member->prev_member  = 0; 
    chptr->members       = member;

    member->next_channel = (cli_user(who))->channel;
    if (member->next_channel)
      member->next_channel->prev_channel = member;
    member->prev_channel = 0;
    (cli_user(who))->channel = member;

    if (chptr->destruct_event)
      remove_destruct_event(chptr);
    ++chptr->users;
    ++((cli_user(who))->joined);
  }
}

/** Remove a person from a channel, given their Membership*
 *
 * @param member A member of a channel.
 *
 * @returns true if there are more people in the channel.
 */
static int remove_member_from_channel(struct Membership* member)
{
  struct Channel* chptr;
  assert(0 != member);
  chptr = member->channel;
  /*
   * unlink channel member list
   */
  if (member->next_member)
    member->next_member->prev_member = member->prev_member;
  if (member->prev_member)
    member->prev_member->next_member = member->next_member;
  else
    member->channel->members = member->next_member; 

  /*
   * If this is the last delayed-join user, may have to clear WASDELJOINS.
   */
  if (IsDelayedJoin(member))
    CheckDelayedJoins(chptr);

  /*
   * unlink client channel list
   */
  if (member->next_channel)
    member->next_channel->prev_channel = member->prev_channel;
  if (member->prev_channel)
    member->prev_channel->next_channel = member->next_channel;
  else
    (cli_user(member->user))->channel = member->next_channel;

  --(cli_user(member->user))->joined;

  member->next_member = membershipFreeList;
  membershipFreeList = member;

  return sub1_from_channel(chptr);
}

/** Check if all the remaining members on the channel are zombies
 *
 * @returns False if the channel has any non zombie members, True otherwise.
 * @see \ref zombie
 */
static int channel_all_zombies(struct Channel* chptr)
{
  struct Membership* member;

  for (member = chptr->members; member; member = member->next_member) {
    if (!IsZombie(member))
      return 0;
  }
  return 1;
}
      

/** Remove a user from a channel
 * This is the generic entry point for removing a user from a channel, this
 * function will remove the client from the channel, and destroy the channel
 * if there are no more normal users left.
 *
 * @param cptr          The client
 * @param chptr         The channel
 */
void remove_user_from_channel(struct Client* cptr, struct Channel* chptr)
{
  
  struct Membership* member;
  assert(0 != chptr);

  if ((member = find_member_link(chptr, cptr))) {
    if (remove_member_from_channel(member)) {
      if (channel_all_zombies(chptr)) {
        /*
         * XXX - this looks dangerous but isn't if we got the referential
         * integrity right for channels
         */
        while (remove_member_from_channel(chptr->members))
          ;
      }
    }
  }
}

/** Remove a user from all channels they are on.
 *
 * This function removes a user from all channels they are on.
 *
 * @param cptr  The client to remove.
 */
void remove_user_from_all_channels(struct Client* cptr)
{
  struct Membership* chan;
  assert(0 != cptr);
  assert(0 != cli_user(cptr));

  while ((chan = (cli_user(cptr))->channel))
    remove_user_from_channel(cptr, chan->channel);
}

/** Check if this user is a legitimate chanop
 *
 * @param cptr  Client to check
 * @param chptr Channel to check
 *
 * @returns True if the user is a chanop (And not a zombie), False otherwise.
 * @see \ref zombie
 */
int is_chan_op(struct Client *cptr, struct Channel *chptr)
{
  struct Membership* member;
  assert(chptr);
  if ((member = find_member_link(chptr, cptr)))
    return (!IsZombie(member) && IsChanOp(member));

  return 0;
}

/** Check if a user is a Zombie on a specific channel.
 *
 * @param cptr          The client to check.
 * @param chptr         The channel to check.
 *
 * @returns True if the client (cptr) is a zombie on the channel (chptr),
 *          False otherwise.
 *
 * @see \ref zombie
 */
int is_zombie(struct Client *cptr, struct Channel *chptr)
{
  struct Membership* member;

  assert(0 != chptr);

  if ((member = find_member_link(chptr, cptr)))
      return IsZombie(member);
  return 0;
}

/** Returns if a user has voice on a channel.
 *
 * @param cptr  The client
 * @param chptr The channel
 *
 * @returns True if the client (cptr) is voiced on (chptr) and is not a zombie.
 * @see \ref zombie
 */
int has_voice(struct Client* cptr, struct Channel* chptr)
{
  struct Membership* member;

  assert(0 != chptr);
  if ((member = find_member_link(chptr, cptr)))
    return (!IsZombie(member) && HasVoice(member));

  return 0;
}

/** Can this member send to a channel
 *
 * A user can speak on a channel iff:
 * <ol>
 *  <li> They didn't use the Apass to gain ops.
 *  <li> They are op'd or voice'd.
 *  <li> You aren't banned.
 *  <li> The channel isn't +m
 *  <li> The channel isn't +n or you are on the channel.
 * </ol>
 *
 * This function will optionally reveal a user on a delayed join channel if
 * they are allowed to send to the channel.
 *
 * @param member        The membership of the user
 * @param reveal        If true, the user will be "revealed" on a delayed
 *                      joined channel. 
 *
 * @returns True if the client can speak on the channel.
 */
int member_can_send_to_channel(struct Membership* member, int reveal)
{
  assert(0 != member);

  /* Discourage using the Apass to get op.  They should use the upass. */
  if (IsChannelManager(member) && *member->channel->mode.upass)
    return 0;

  if (IsVoicedOrOpped(member))
    return 1;
  /*
   * If it's moderated, and you aren't a privileged user, you can't
   * speak.  
   */
  if (member->channel->mode.mode & MODE_MODERATED)
    return 0;
  /*
   * If you're banned then you can't speak either.
   * but because of the amount of CPU time that is_banned chews
   * we only check it for our clients.
   */
  if (MyUser(member->user) && is_banned(member))
    return 0;

  if (IsDelayedJoin(member) && reveal)
    RevealDelayedJoin(member);

  return 1;
}

/** Check if a client can send to a channel.
 *
 * Has the added check over member_can_send_to_channel() of servers can
 * always speak.
 *
 * @param cptr  The client to check
 * @param chptr The channel to check
 * @param reveal If the user should be revealed (see 
 *              member_can_send_to_channel())
 *
 * @returns true if the client is allowed to speak on the channel, false 
 *              otherwise
 *
 * @see member_can_send_to_channel()
 */
int client_can_send_to_channel(struct Client *cptr, struct Channel *chptr, int reveal)
{
  struct Membership *member;
  assert(0 != cptr); 
  /*
   * Servers can always speak on channels.
   */
  if (IsServer(cptr))
    return 1;

  member = find_channel_member(cptr, chptr);

  /*
   * You can't speak if you're off channel, and it is +n (no external messages)
   * or +m (moderated).
   */
  if (!member) {
    if ((chptr->mode.mode & (MODE_NOPRIVMSGS|MODE_MODERATED)) ||
        ((chptr->mode.mode & MODE_REGONLY) && !IsAccount(cptr)))
      return 0;
    else
      return !find_ban(cptr, chptr->banlist);
  }
  return member_can_send_to_channel(member, reveal);
}

/** Returns the name of a channel that prevents the user from changing nick.
 * if a member and not (opped or voiced) and (banned or moderated), return
 * the name of the first channel banned on.
 *
 * @param cptr  The client
 *
 * @returns the name of the first channel banned on, or NULL if the user
 *          can change nicks.
 */
const char* find_no_nickchange_channel(struct Client* cptr)
{
  if (MyUser(cptr)) {
    struct Membership* member;
    for (member = (cli_user(cptr))->channel; member;
         member = member->next_channel) {
        if (!IsVoicedOrOpped(member) &&
            (is_banned(member) ||
             (member->channel->mode.mode & MODE_MODERATED)))
        return member->channel->chname;
    }
  }
  return 0;
}


/** Fill mbuf/pbuf with modes from chptr
 * write the "simple" list of channel modes for channel chptr onto buffer mbuf
 * with the parameters in pbuf as visible by cptr.
 *
 * This function will hide keys from non-op'd, non-server clients.
 *
 * @param cptr  The client to generate the mode for.
 * @param mbuf  The buffer to write the modes into.
 * @param pbuf  The buffer to write the mode parameters into.
 * @param buflen The length of the buffers.
 * @param chptr The channel to get the modes from.
 * @param member The membership of this client on this channel (or NULL
 *              if this client isn't on this channel)
 *
 */
void channel_modes(struct Client *cptr, char *mbuf, char *pbuf, int buflen,
                          struct Channel *chptr, struct Membership *member)
{
  int previous_parameter = 0;

  assert(0 != mbuf);
  assert(0 != pbuf);
  assert(0 != chptr);

  *mbuf++ = '+';
  if (chptr->mode.mode & MODE_SECRET)
    *mbuf++ = 's';
  else if (chptr->mode.mode & MODE_PRIVATE)
    *mbuf++ = 'p';
  if (chptr->mode.mode & MODE_MODERATED)
    *mbuf++ = 'm';
  if (chptr->mode.mode & MODE_TOPICLIMIT)
    *mbuf++ = 't';
  if (chptr->mode.mode & MODE_INVITEONLY)
    *mbuf++ = 'i';
  if (chptr->mode.mode & MODE_NOPRIVMSGS)
    *mbuf++ = 'n';
  if (chptr->mode.mode & MODE_REGONLY)
    *mbuf++ = 'r';
  if (chptr->mode.mode & MODE_DELJOINS)
    *mbuf++ = 'D';
  else if (MyUser(cptr) && (chptr->mode.mode & MODE_WASDELJOINS))
    *mbuf++ = 'd';
  if (chptr->mode.limit) {
    *mbuf++ = 'l';
    ircd_snprintf(0, pbuf, buflen, "%u", chptr->mode.limit);
    previous_parameter = 1;
  }

  if (*chptr->mode.key) {
    *mbuf++ = 'k';
    if (previous_parameter)
      strcat(pbuf, " ");
    if (is_chan_op(cptr, chptr) || IsServer(cptr)) {
      strcat(pbuf, chptr->mode.key);
    } else
      strcat(pbuf, "*");
    previous_parameter = 1;
  }
  if (*chptr->mode.apass) {
    *mbuf++ = 'A';
    if (previous_parameter)
      strcat(pbuf, " ");
    if (IsServer(cptr)) {
      strcat(pbuf, chptr->mode.apass);
    } else
      strcat(pbuf, "*");
    previous_parameter = 1;
  }
  if (*chptr->mode.upass) {
    *mbuf++ = 'U';
    if (previous_parameter)
      strcat(pbuf, " ");
    if (IsServer(cptr) || (member && IsChanOp(member) && OpLevel(member) == 0)) {
      strcat(pbuf, chptr->mode.upass);
    } else
      strcat(pbuf, "*");
  }
  *mbuf = '\0';
}

/** Compare two members oplevel
 *
 * @param mp1   Pointer to a pointer to a membership
 * @param mp2   Pointer to a pointer to a membership
 *
 * @returns 0 if equal, -1 if mp1 is lower, +1 otherwise.
 *
 * Used for qsort(3).
 */
int compare_member_oplevel(const void *mp1, const void *mp2)
{
  struct Membership const* member1 = *(struct Membership const**)mp1;
  struct Membership const* member2 = *(struct Membership const**)mp2;
  if (member1->oplevel == member2->oplevel)
    return 0;
  return (member1->oplevel < member2->oplevel) ? -1 : 1;
}

/* send "cptr" a full list of the modes for channel chptr.
 *
 * Sends a BURST line to cptr, bursting all the modes for the channel.
 *
 * @param cptr  Client pointer
 * @param chptr Channel pointer
 */
void send_channel_modes(struct Client *cptr, struct Channel *chptr)
{
  /* The order in which modes are generated is now mandatory */
  static unsigned int current_flags[4] =
      { 0, CHFL_VOICE, CHFL_CHANOP, CHFL_CHANOP | CHFL_VOICE };
  int                first = 1;
  int                full  = 1;
  int                flag_cnt = 0;
  int                new_mode = 0;
  size_t             len;
  struct Membership* member;
  struct Ban*        lp2;
  char modebuf[MODEBUFLEN];
  char parabuf[MODEBUFLEN];
  struct MsgBuf *mb;
  int                 number_of_ops = 0;
  int                 opped_members_index = 0;
  struct Membership** opped_members = NULL;
  int                 last_oplevel = 0;
  int                 feat_oplevels = (chptr->mode.apass[0]) != '\0';

  assert(0 != cptr);
  assert(0 != chptr); 

  if (IsLocalChannel(chptr->chname))
    return;

  member = chptr->members;
  lp2 = chptr->banlist;

  *modebuf = *parabuf = '\0';
  channel_modes(cptr, modebuf, parabuf, sizeof(parabuf), chptr, 0);

  for (first = 1; full; first = 0)      /* Loop for multiple messages */
  {
    full = 0;                   /* Assume by default we get it
                                 all in one message */

    /* (Continued) prefix: "<Y> B <channel> <TS>" */
    /* is there any better way we can do this? */
    mb = msgq_make(&me, "%C " TOK_BURST " %H %Tu", &me, chptr,
                   chptr->creationtime);

    if (first && modebuf[1])    /* Add simple modes (Aiklmnpstu)
                                 if first message */
    {
      /* prefix: "<Y> B <channel> <TS>[ <modes>[ <params>]]" */
      msgq_append(&me, mb, " %s", modebuf);

      if (*parabuf)
        msgq_append(&me, mb, " %s", parabuf);
    }

    /*
     * Attach nicks, comma separated " nick[:modes],nick[:modes],..."
     *
     * First find all opless members.
     * Run 2 times over all members, to group the members with
     * and without voice together.
     * Then run 2 times over all opped members (which are ordered
     * by op-level) to also group voice and non-voice together.
     */
    for (first = 1; flag_cnt < 4; new_mode = 1, ++flag_cnt)
    {
      while (member)
      {
        if (flag_cnt < 2 && IsChanOp(member))
        {
          /*
           * The first loop (to find all non-voice/op), we count the ops.
           * The second loop (to find all voiced non-ops), store the ops
           * in a dynamic array.
           */
          if (flag_cnt == 0)
            ++number_of_ops;
          else
            opped_members[opped_members_index++] = member;
        }
        /* Only handle the members with the flags that we are interested in. */
        if ((member->status & CHFL_VOICED_OR_OPPED) == current_flags[flag_cnt])
        {
          if (msgq_bufleft(mb) < NUMNICKLEN + 3 + MAXOPLEVELDIGITS)
            /* The 3 + MAXOPLEVELDIGITS is a possible ",:v999". */
          {
            full = 1;           /* Make sure we continue after
                                   sending it so far */
            /* Ensure the new BURST line contains the current
             * ":mode", except when there is no mode yet. */
            new_mode = (flag_cnt > 0) ? 1 : 0;
            break;              /* Do not add this member to this message */
          }
          msgq_append(&me, mb, "%c%C", first ? ' ' : ',', member->user);
          first = 0;              /* From now on, use commas to add new nicks */

          /*
           * Do we have a nick with a new mode ?
           * Or are we starting a new BURST line?
           */
          if (new_mode)
          {
            /*
             * This means we are at the _first_ member that has only
             * voice, or the first member that has only ops, or the
             * first member that has voice and ops (so we get here
             * at most three times, plus once for every start of
             * a continued BURST line where only these modes is current.
             * In the two cases where the current mode includes ops,
             * we need to add the _absolute_ value of the oplevel to the mode.
             */
            char tbuf[3 + MAXOPLEVELDIGITS] = ":";
            int loc = 1;

            if (HasVoice(member))       /* flag_cnt == 1 or 3 */
              tbuf[loc++] = 'v';
            if (IsChanOp(member))       /* flag_cnt == 2 or 3 */
            {
              /* append the absolute value of the oplevel */
              if (feat_oplevels)
                loc += ircd_snprintf(0, tbuf + loc, sizeof(tbuf) - loc, "%u", last_oplevel = member->oplevel);
              else
                tbuf[loc++] = 'o';
            }
            tbuf[loc] = '\0';
            msgq_append(&me, mb, tbuf);
            new_mode = 0;
          }
          else if (feat_oplevels && flag_cnt > 1 && last_oplevel != member->oplevel)
          {
            /*
             * This can't be the first member of a (continued) BURST
             * message because then either flag_cnt == 0 or new_mode == 1
             * Now we need to append the incremental value of the oplevel.
             */
            char tbuf[2 + MAXOPLEVELDIGITS];
            ircd_snprintf(0, tbuf, sizeof(tbuf), ":%u", member->oplevel - last_oplevel);
            last_oplevel = member->oplevel;
            msgq_append(&me, mb, tbuf);
          }
        }
        /* Go to the next `member'. */
        if (flag_cnt < 2)
          member = member->next_member;
        else
          member = opped_members[++opped_members_index];
      }
      if (full)
        break;

      /* Point `member' at the start of the list again. */
      if (flag_cnt == 0)
      {
        member = chptr->members;
        /* Now, after one loop, we know the number of ops and can
         * allocate the dynamic array with pointer to the ops. */
        opped_members = (struct Membership**)
          MyMalloc((number_of_ops + 1) * sizeof(struct Membership*));
        opped_members[number_of_ops] = NULL;    /* Needed for loop termination */
      }
      else
      {
        /* At the end of the second loop, sort the opped members with
         * increasing op-level, so that we will output them in the
         * correct order (and all op-level increments stay positive) */
        if (flag_cnt == 1)
          qsort(opped_members, number_of_ops,
                sizeof(struct Membership*), compare_member_oplevel);
        /* The third and fourth loop run only over the opped members. */
        member = opped_members[(opped_members_index = 0)];
      }

    } /* loop over 0,+v,+o,+ov */

    if (!full)
    {
      /* Attach all bans, space separated " :%ban ban ..." */
      for (first = 2; lp2; lp2 = lp2->next)
      {
        len = strlen(lp2->banstr);
        if (msgq_bufleft(mb) < len + 1 + first)
          /* The +1 stands for the added ' '.
           * The +first stands for the added ":%".
           */
        {
          full = 1;
          break;
        }
        msgq_append(&me, mb, " %s%s", first ? ":%" : "",
                    lp2->banstr);
        first = 0;
      }
    }

    send_buffer(cptr, mb, 0);  /* Send this message */
    msgq_clean(mb);
  }                             /* Continue when there was something
                                 that didn't fit (full==1) */
  if (opped_members)
    MyFree(opped_members);
  if (feature_bool(FEAT_TOPIC_BURST) && (chptr->topic[0] != '\0'))
      sendcmdto_one(&me, CMD_TOPIC, cptr, "%H %Tu %Tu :%s", chptr,
                    chptr->creationtime, chptr->topic_time, chptr->topic);
}

/** Canonify a mask.
 * pretty_mask
 *
 * @author Carlo Wood (Run), 
 * 05 Oct 1998.
 *
 * When the nick is longer then NICKLEN, it is cut off (its an error of course).
 * When the user name or host name are too long (USERLEN and HOSTLEN
 * respectively) then they are cut off at the start with a '*'.
 *
 * The following transformations are made:
 *
 * 1)   xxx             -> nick!*@*
 * 2)   xxx.xxx         -> *!*\@host
 * 3)   xxx\!yyy         -> nick!user\@*
 * 4)   xxx\@yyy         -> *!user\@host
 * 5)   xxx!yyy\@zzz     -> nick!user\@host
 *
 * @param mask  The uncanonified mask.
 * @returns The updated mask in a static buffer.
 */
char *pretty_mask(char *mask)
{
  static char star[2] = { '*', 0 };
  static char retmask[NICKLEN + USERLEN + HOSTLEN + 3];
  char *last_dot = NULL;
  char *ptr;

  /* Case 1: default */
  char *nick = mask;
  char *user = star;
  char *host = star;

  /* Do a _single_ pass through the characters of the mask: */
  for (ptr = mask; *ptr; ++ptr)
  {
    if (*ptr == '!')
    {
      /* Case 3 or 5: Found first '!' (without finding a '@' yet) */
      user = ++ptr;
      host = star;
    }
    else if (*ptr == '@')
    {
      /* Case 4: Found last '@' (without finding a '!' yet) */
      nick = star;
      user = mask;
      host = ++ptr;
    }
    else if (*ptr == '.')
    {
      /* Case 2: Found last '.' (without finding a '!' or '@' yet) */
      last_dot = ptr;
      continue;
    }
    else
      continue;
    for (; *ptr; ++ptr)
    {
      if (*ptr == '@')
      {
        /* Case 4 or 5: Found last '@' */
        host = ptr + 1;
      }
    }
    break;
  }
  if (user == star && last_dot)
  {
    /* Case 2: */
    nick = star;
    user = star;
    host = mask;
  }
  /* Check lengths */
  if (nick != star)
  {
    char *nick_end = (user != star) ? user - 1 : ptr;
    if (nick_end - nick > NICKLEN)
      nick[NICKLEN] = 0;
    *nick_end = 0;
  }
  if (user != star)
  {
    char *user_end = (host != star) ? host - 1 : ptr;
    if (user_end - user > USERLEN)
    {
      user = user_end - USERLEN;
      *user = '*';
    }
    *user_end = 0;
  }
  if (host != star && ptr - host > HOSTLEN)
  {
    host = ptr - HOSTLEN;
    *host = '*';
  }
  ircd_snprintf(0, retmask, sizeof(retmask), "%s!%s@%s", nick, user, host);
  return retmask;
}

/** send a banlist to a client for a channel
 *
 * @param cptr  Client to send the banlist to.
 * @param chptr Channel whose banlist to send.
 */
static void send_ban_list(struct Client* cptr, struct Channel* chptr)
{
  struct Ban* lp;

  assert(0 != cptr);
  assert(0 != chptr);

  for (lp = chptr->banlist; lp; lp = lp->next)
    send_reply(cptr, RPL_BANLIST, chptr->chname, lp->banstr,
               lp->who, lp->when);

  send_reply(cptr, RPL_ENDOFBANLIST, chptr->chname);
}

/** Check a key against a keyring.
 * We are now treating the key part of /join channellist key as a key
 * ring; that is, we try one key against the actual channel key, and if that
 * doesn't work, we try the next one, and so on. -Kev -Texaco
 * Returns: 0 on match, 1 otherwise
 * This version contributed by SeKs \<intru@info.polymtl.ca\>
 *
 * @param key           Key to check
 * @param keyring       Comma separated list of keys
 *
 * @returns True if the key was found and matches, false otherwise.
 */
static int compall(char *key, char *keyring)
{
  char *p1;

top:
  p1 = key;                     /* point to the key... */
  while (*p1 && *p1 == *keyring)
  {                             /* step through the key and ring until they
                                   don't match... */
    p1++;
    keyring++;
  }

  if (!*p1 && (!*keyring || *keyring == ','))
    /* ok, if we're at the end of the and also at the end of one of the keys
       in the keyring, we have a match */
    return 0;

  if (!*keyring)                /* if we're at the end of the key ring, there
                                   weren't any matches, so we return 1 */
    return 1;

  /* Not at the end of the key ring, so step
     through to the next key in the ring: */
  while (*keyring && *(keyring++) != ',');

  goto top;                     /* and check it against the key */
}

/** Returns if a user can join a channel with a specific key.
 *
 * @param sptr  The client trying to join
 * @param chptr The channel to join
 * @param key   The key to use
 *
 * @returns any error that occurred bit-wise OR'd with MAGIC_OPER_OVERRIDE
 *          if the oper used the magic key, 0 if no error occurred.
 */
int can_join(struct Client *sptr, struct Channel *chptr, char *key)
{
  int overrideJoin = 0;  
  
  /*
   * Now a banned user CAN join if invited -- Nemesi
   * Now a user CAN escape channel limit if invited -- bfriendly
   * Now a user CAN escape anything if invited -- Isomer
   */

  if (IsInvited(sptr, chptr))
    return 0;
  
  /* An oper can force a join on a local channel using "OVERRIDE" as the key. 
     a HACK(4) notice will be sent if he would not have been supposed
     to join normally. */ 
  if (IsLocalChannel(chptr->chname) && HasPriv(sptr, PRIV_WALK_LCHAN) &&
      !BadPtr(key) && compall("OVERRIDE",chptr->mode.key) != 0 &&
      compall("OVERRIDE",key) == 0)
    overrideJoin = MAGIC_OPER_OVERRIDE;

  if (chptr->mode.mode & MODE_INVITEONLY)
        return overrideJoin + ERR_INVITEONLYCHAN;
        
  if (chptr->mode.limit && chptr->users >= chptr->mode.limit)
        return overrideJoin + ERR_CHANNELISFULL;

  if ((chptr->mode.mode & MODE_REGONLY) && !IsAccount(sptr))
        return overrideJoin + ERR_NEEDREGGEDNICK;
        
  if (find_ban(sptr, chptr->banlist))
        return overrideJoin + ERR_BANNEDFROMCHAN;
  
  /*
   * now using compall (above) to test against a whole key ring -Kev
   */
  if (*chptr->mode.key && (EmptyString(key) || compall(chptr->mode.key, key)))
    return overrideJoin + ERR_BADCHANNELKEY;

  if (overrideJoin)     
        return ERR_DONTCHEAT;
        
  return 0;
}

/** Remove bells and commas from channel name
 *
 * @param cn    Channel name to clean, modified in place.
 */
void clean_channelname(char *cn)
{
  int i;

  for (i = 0; cn[i]; i++) {
    if (i >= CHANNELLEN || !IsChannelChar(cn[i])) {
      cn[i] = '\0';
      return;
    }
    if (IsChannelLower(cn[i])) {
      cn[i] = ToLower(cn[i]);
#ifndef FIXME
      /*
       * Remove for .08+
       * toupper(0xd0)
       */
      if ((unsigned char)(cn[i]) == 0xd0)
        cn[i] = (char) 0xf0;
#endif
    }
  }
}

/** Get a channel block, creating if necessary.
 *  Get Channel block for chname (and allocate a new channel
 *  block, if it didn't exists before).
 *
 * @param cptr          Client joining the channel.
 * @param chname        The name of the channel to join.
 * @param flag          set to CGT_CREATE to create the channel if it doesn't 
 *                      exist
 *
 * @returns NULL if the channel is invalid, doesn't exist and CGT_CREATE 
 *      wasn't specified or a pointer to the channel structure
 */
struct Channel *get_channel(struct Client *cptr, char *chname, ChannelGetType flag)
{
  struct Channel *chptr;
  int len;

  if (EmptyString(chname))
    return NULL;

  len = strlen(chname);
  if (MyUser(cptr) && len > CHANNELLEN)
  {
    len = CHANNELLEN;
    *(chname + CHANNELLEN) = '\0';
  }
  if ((chptr = FindChannel(chname)))
    return (chptr);
  if (flag == CGT_CREATE)
  {
    chptr = (struct Channel*) MyMalloc(sizeof(struct Channel) + len);
    assert(0 != chptr);
    ++UserStats.channels;
    memset(chptr, 0, sizeof(struct Channel));
    strcpy(chptr->chname, chname);
    if (GlobalChannelList)
      GlobalChannelList->prev = chptr;
    chptr->prev = NULL;
    chptr->next = GlobalChannelList;
    chptr->creationtime = MyUser(cptr) ? TStime() : (time_t) 0;
    GlobalChannelList = chptr;
    hAddChannel(chptr);
  }
  return chptr;
}

/** invite a user to a channel.
 *
 * Adds an invite for a user to a channel.  Limits the number of invites
 * to FEAT_MAXCHANNELSPERUSER.  Does not sent notification to the user.
 *
 * @param cptr  The client to be invited.
 * @param chptr The channel to be invited to.
 */
void add_invite(struct Client *cptr, struct Channel *chptr)
{
  struct SLink *inv, **tmp;

  del_invite(cptr, chptr);
  /*
   * Delete last link in chain if the list is max length
   */
  assert(list_length((cli_user(cptr))->invited) == (cli_user(cptr))->invites);
  if ((cli_user(cptr))->invites >= feature_int(FEAT_MAXCHANNELSPERUSER))
    del_invite(cptr, (cli_user(cptr))->invited->value.chptr);
  /*
   * Add client to channel invite list
   */
  inv = make_link();
  inv->value.cptr = cptr;
  inv->next = chptr->invites;
  chptr->invites = inv;
  /*
   * Add channel to the end of the client invite list
   */
  for (tmp = &((cli_user(cptr))->invited); *tmp; tmp = &((*tmp)->next));
  inv = make_link();
  inv->value.chptr = chptr;
  inv->next = NULL;
  (*tmp) = inv;
  (cli_user(cptr))->invites++;
}

/** Delete an invite
 * Delete Invite block from channel invite list and client invite list
 *
 * @param cptr  Client pointer
 * @param chptr Channel pointer
 */
void del_invite(struct Client *cptr, struct Channel *chptr)
{
  struct SLink **inv, *tmp;

  for (inv = &(chptr->invites); (tmp = *inv); inv = &tmp->next)
    if (tmp->value.cptr == cptr)
    {
      *inv = tmp->next;
      free_link(tmp);
      tmp = 0;
      (cli_user(cptr))->invites--;
      break;
    }

  for (inv = &((cli_user(cptr))->invited); (tmp = *inv); inv = &tmp->next)
    if (tmp->value.chptr == chptr)
    {
      *inv = tmp->next;
      free_link(tmp);
      tmp = 0;
      break;
    }
}

/** @page zombie Explanation of Zombies
 *
 * Synopsis:
 *
 * A channel member is turned into a zombie when he is kicked from a
 * channel but his server has not acknowledged the kick.  Servers that
 * see the member as a zombie can accept actions he performed before
 * being kicked, without allowing chanop operations from outsiders or
 * desyncing the network.
 *
 * Consider:
 * <pre>
 *                     client
 *                       |
 *                       c
 *                       |
 *     X --a--> A --b--> B --d--> D
 *                       |
 *                      who
 * </pre>
 *
 * Where `who' is being KICK-ed by a "KICK" message received by server 'A'
 * via 'a', or on server 'B' via either 'b' or 'c', or on server D via 'd'.
 *
 * a) On server A : set CHFL_ZOMBIE for `who' (lp) and pass on the KICK.
 *    Remove the user immediately when no users are left on the channel.
 * b) On server B : remove the user (who/lp) from the channel, send a
 *    PART upstream (to A) and pass on the KICK.
 * c) KICKed by `client'; On server B : remove the user (who/lp) from the
 *    channel, and pass on the KICK.
 * d) On server D : remove the user (who/lp) from the channel, and pass on
 *    the KICK.
 *
 * Note:
 * - Setting the ZOMBIE flag never hurts, we either remove the
 *   client after that or we don't.
 * - The KICK message was already passed on, as should be in all cases.
 * - `who' is removed in all cases except case a) when users are left.
 * - A PART is only sent upstream in case b).
 *
 * 2 aug 97:
 * <pre>
 *              6
 *              |
 *  1 --- 2 --- 3 --- 4 --- 5
 *        |           |
 *      kicker       who
 * </pre>
 *
 * We also need to turn 'who' into a zombie on servers 1 and 6,
 * because a KICK from 'who' (kicking someone else in that direction)
 * can arrive there afterward - which should not be bounced itself.
 * Therefore case a) also applies for servers 1 and 6.
 *
 * --Run
 */

/** Turn a user on a channel into a zombie
 * This function turns a user into a zombie (see \ref zombie)
 *
 * @param member  The structure representing this user on this channel.
 * @param who     The client that is being kicked.
 * @param cptr    The connection the kick came from.
 * @param sptr    The client that is doing the kicking.
 * @param chptr   The channel the user is being kicked from.
 */
void make_zombie(struct Membership* member, struct Client* who, 
                struct Client* cptr, struct Client* sptr, struct Channel* chptr)
{
  assert(0 != member);
  assert(0 != who);
  assert(0 != cptr);
  assert(0 != chptr);

  /* Default for case a): */
  SetZombie(member);

  /* Case b) or c) ?: */
  if (MyUser(who))      /* server 4 */
  {
    if (IsServer(cptr)) /* Case b) ? */
      sendcmdto_one(who, CMD_PART, cptr, "%H", chptr);
    remove_user_from_channel(who, chptr);
    return;
  }
  if (cli_from(who) == cptr)        /* True on servers 1, 5 and 6 */
  {
    struct Client *acptr = IsServer(sptr) ? sptr : (cli_user(sptr))->server;
    for (; acptr != &me; acptr = (cli_serv(acptr))->up)
      if (acptr == (cli_user(who))->server)   /* Case d) (server 5) */
      {
        remove_user_from_channel(who, chptr);
        return;
      }
  }

  /* Case a) (servers 1, 2, 3 and 6) */
  if (channel_all_zombies(chptr))
    remove_user_from_channel(who, chptr);

  /* XXX Can't actually call Debug here; if the channel is all zombies,
   * chptr will no longer exist when we get here.
  Debug((DEBUG_INFO, "%s is now a zombie on %s", who->name, chptr->chname));
  */
}

/** returns the number of zombies on a channel
 * @param chptr Channel to count zombies in.
 *
 * @returns The number of zombies on the channel.
 */
int number_of_zombies(struct Channel *chptr)
{
  struct Membership* member;
  int                count = 0;

  assert(0 != chptr);
  for (member = chptr->members; member; member = member->next_member) {
    if (IsZombie(member))
      ++count;
  }
  return count;
}

/** Concatenate some strings together.
 * This helper function builds an argument string in strptr, consisting
 * of the original string, a space, and str1 and str2 concatenated (if,
 * of course, str2 is not NULL)
 *
 * @param strptr        The buffer to concatenate into
 * @param strptr_i      modified offset to the position to modify
 * @param str1          The string to concatenate from.
 * @param str2          The second string to contatenate from.
 * @param c             Charactor to separate the string from str1 and str2.
 */
static void
build_string(char *strptr, int *strptr_i, const char *str1,
             const char *str2, char c)
{
  if (c)
    strptr[(*strptr_i)++] = c;

  while (*str1)
    strptr[(*strptr_i)++] = *(str1++);

  if (str2)
    while (*str2)
      strptr[(*strptr_i)++] = *(str2++);

  strptr[(*strptr_i)] = '\0';
}

/** Flush out the modes
 * This is the workhorse of our ModeBuf suite; this actually generates the
 * output MODE commands, HACK notices, or whatever.  It's pretty complicated.
 *
 * @param mbuf  The mode buffer to flush
 * @param all   If true, flush all modes, otherwise leave partial modes in the
 *              buffer.
 *
 * @returns 0
 */
static int
modebuf_flush_int(struct ModeBuf *mbuf, int all)
{
  /* we only need the flags that don't take args right now */
  static int flags[] = {
/*  MODE_CHANOP,        'o', */
/*  MODE_VOICE,         'v', */
    MODE_PRIVATE,       'p',
    MODE_SECRET,        's',
    MODE_MODERATED,     'm',
    MODE_TOPICLIMIT,    't',
    MODE_INVITEONLY,    'i',
    MODE_NOPRIVMSGS,    'n',
    MODE_REGONLY,       'r',
    MODE_DELJOINS,      'D',
    MODE_WASDELJOINS,   'd',
/*  MODE_KEY,           'k', */
/*  MODE_BAN,           'b', */
    MODE_LIMIT,         'l',
/*  MODE_APASS,         'A', */
/*  MODE_UPASS,         'U', */
    0x0, 0x0
  };
  int i;
  int *flag_p;

  struct Client *app_source; /* where the MODE appears to come from */

  char addbuf[20]; /* accumulates +psmtin, etc. */
  int addbuf_i = 0;
  char rembuf[20]; /* accumulates -psmtin, etc. */
  int rembuf_i = 0;
  char *bufptr; /* we make use of indirection to simplify the code */
  int *bufptr_i;

  char addstr[BUFSIZE]; /* accumulates MODE parameters to add */
  int addstr_i;
  char remstr[BUFSIZE]; /* accumulates MODE parameters to remove */
  int remstr_i;
  char *strptr; /* more indirection to simplify the code */
  int *strptr_i;

  int totalbuflen = BUFSIZE - 200; /* fuzz factor -- don't overrun buffer! */
  int tmp;

  char limitbuf[20]; /* convert limits to strings */

  unsigned int limitdel = MODE_LIMIT;

  assert(0 != mbuf);

  /* If the ModeBuf is empty, we have nothing to do */
  if (mbuf->mb_add == 0 && mbuf->mb_rem == 0 && mbuf->mb_count == 0)
    return 0;

  /* Ok, if we were given the OPMODE flag, or its a server, hide the source.
   */
  if (mbuf->mb_dest & MODEBUF_DEST_OPMODE || IsServer(mbuf->mb_source))
    app_source = &me;
  else
    app_source = mbuf->mb_source;

  /*
   * Account for user we're bouncing; we have to get it in on the first
   * bounced MODE, or we could have problems
   */
  if (mbuf->mb_dest & MODEBUF_DEST_DEOP)
    totalbuflen -= 6; /* numeric nick == 5, plus one space */

  /* Calculate the simple flags */
  for (flag_p = flags; flag_p[0]; flag_p += 2) {
    if (*flag_p & mbuf->mb_add)
      addbuf[addbuf_i++] = flag_p[1];
    else if (*flag_p & mbuf->mb_rem)
      rembuf[rembuf_i++] = flag_p[1];
  }

  /* Now go through the modes with arguments... */
  for (i = 0; i < mbuf->mb_count; i++) {
    if (MB_TYPE(mbuf, i) & MODE_ADD) { /* adding or removing? */
      bufptr = addbuf;
      bufptr_i = &addbuf_i;
    } else {
      bufptr = rembuf;
      bufptr_i = &rembuf_i;
    }

    if (MB_TYPE(mbuf, i) & (MODE_CHANOP | MODE_VOICE)) {
      tmp = strlen(cli_name(MB_CLIENT(mbuf, i)));

      if ((totalbuflen - IRCD_MAX(5, tmp)) <= 0) /* don't overflow buffer */
        MB_TYPE(mbuf, i) |= MODE_SAVE; /* save for later */
      else {
        bufptr[(*bufptr_i)++] = MB_TYPE(mbuf, i) & MODE_CHANOP ? 'o' : 'v';
        totalbuflen -= IRCD_MAX(5, tmp) + 1;
      }
    } else if (MB_TYPE(mbuf, i) & (MODE_BAN | MODE_APASS | MODE_UPASS)) {
      tmp = strlen(MB_STRING(mbuf, i));

      if ((totalbuflen - tmp) <= 0) /* don't overflow buffer */
        MB_TYPE(mbuf, i) |= MODE_SAVE; /* save for later */
      else {
        char mode_char;
        switch(MB_TYPE(mbuf, i) & (MODE_BAN | MODE_APASS | MODE_UPASS))
        {
          case MODE_APASS:
            mode_char = 'A';
            break;
          case MODE_UPASS:
            mode_char = 'U';
            break;
          default:
            mode_char = 'b';
            break;
        }
        bufptr[(*bufptr_i)++] = mode_char;
        totalbuflen -= tmp + 1;
      }
    } else if (MB_TYPE(mbuf, i) & MODE_KEY) {
      tmp = (mbuf->mb_dest & MODEBUF_DEST_NOKEY ? 1 :
             strlen(MB_STRING(mbuf, i)));

      if ((totalbuflen - tmp) <= 0) /* don't overflow buffer */
        MB_TYPE(mbuf, i) |= MODE_SAVE; /* save for later */
      else {
        bufptr[(*bufptr_i)++] = 'k';
        totalbuflen -= tmp + 1;
      }
    } else if (MB_TYPE(mbuf, i) & MODE_LIMIT) {
      /* if it's a limit, we also format the number */
      ircd_snprintf(0, limitbuf, sizeof(limitbuf), "%u", MB_UINT(mbuf, i));

      tmp = strlen(limitbuf);

      if ((totalbuflen - tmp) <= 0) /* don't overflow buffer */
        MB_TYPE(mbuf, i) |= MODE_SAVE; /* save for later */
      else {
        bufptr[(*bufptr_i)++] = 'l';
        totalbuflen -= tmp + 1;
      }
    }
  }

  /* terminate the mode strings */
  addbuf[addbuf_i] = '\0';
  rembuf[rembuf_i] = '\0';

  /* If we're building a user visible MODE or HACK... */
  if (mbuf->mb_dest & (MODEBUF_DEST_CHANNEL | MODEBUF_DEST_HACK2 |
                       MODEBUF_DEST_HACK3   | MODEBUF_DEST_HACK4 |
                       MODEBUF_DEST_LOG)) {
    /* Set up the parameter strings */
    addstr[0] = '\0';
    addstr_i = 0;
    remstr[0] = '\0';
    remstr_i = 0;

    for (i = 0; i < mbuf->mb_count; i++) {
      if (MB_TYPE(mbuf, i) & MODE_SAVE)
        continue;

      if (MB_TYPE(mbuf, i) & MODE_ADD) { /* adding or removing? */
        strptr = addstr;
        strptr_i = &addstr_i;
      } else {
        strptr = remstr;
        strptr_i = &remstr_i;
      }

      /* deal with clients... */
      if (MB_TYPE(mbuf, i) & (MODE_CHANOP | MODE_VOICE))
        build_string(strptr, strptr_i, cli_name(MB_CLIENT(mbuf, i)), 0, ' ');

      /* deal with bans... */
      else if (MB_TYPE(mbuf, i) & MODE_BAN)
        build_string(strptr, strptr_i, MB_STRING(mbuf, i), 0, ' ');

      /* deal with keys... */
      else if (MB_TYPE(mbuf, i) & MODE_KEY)
        build_string(strptr, strptr_i, mbuf->mb_dest & MODEBUF_DEST_NOKEY ?
                     "*" : MB_STRING(mbuf, i), 0, ' ');

      /* deal with invisible passwords */
      else if (MB_TYPE(mbuf, i) & (MODE_APASS | MODE_UPASS))
        build_string(strptr, strptr_i, "*", 0, ' ');

      /*
       * deal with limit; note we cannot include the limit parameter if we're
       * removing it
       */
      else if ((MB_TYPE(mbuf, i) & (MODE_ADD | MODE_LIMIT)) ==
               (MODE_ADD | MODE_LIMIT))
        build_string(strptr, strptr_i, limitbuf, 0, ' ');
    }

    /* send the messages off to their destination */
    if (mbuf->mb_dest & MODEBUF_DEST_HACK2)
      sendto_opmask_butone(0, SNO_HACK2, "HACK(2): %s MODE %s %s%s%s%s%s%s "
                           "[%Tu]",
                           cli_name(feature_bool(FEAT_HIS_SNOTICES) ?
                                    mbuf->mb_source : app_source),
                           mbuf->mb_channel->chname,
                           rembuf_i ? "-" : "", rembuf, addbuf_i ? "+" : "",
                           addbuf, remstr, addstr,
                           mbuf->mb_channel->creationtime);

    if (mbuf->mb_dest & MODEBUF_DEST_HACK3)
      sendto_opmask_butone(0, SNO_HACK3, "BOUNCE or HACK(3): %s MODE %s "
                           "%s%s%s%s%s%s [%Tu]",
                           cli_name(feature_bool(FEAT_HIS_SNOTICES) ? 
                                    mbuf->mb_source : app_source),
                           mbuf->mb_channel->chname, rembuf_i ? "-" : "",
                           rembuf, addbuf_i ? "+" : "", addbuf, remstr, addstr,
                           mbuf->mb_channel->creationtime);

    if (mbuf->mb_dest & MODEBUF_DEST_HACK4)
      sendto_opmask_butone(0, SNO_HACK4, "HACK(4): %s MODE %s %s%s%s%s%s%s "
                           "[%Tu]",
                           cli_name(feature_bool(FEAT_HIS_SNOTICES) ?
                                    mbuf->mb_source : app_source),
                           mbuf->mb_channel->chname,
                           rembuf_i ? "-" : "", rembuf, addbuf_i ? "+" : "",
                           addbuf, remstr, addstr,
                           mbuf->mb_channel->creationtime);

    if (mbuf->mb_dest & MODEBUF_DEST_LOG)
      log_write(LS_OPERMODE, L_INFO, LOG_NOSNOTICE,
                "%#C OPMODE %H %s%s%s%s%s%s", mbuf->mb_source,
                mbuf->mb_channel, rembuf_i ? "-" : "", rembuf,
                addbuf_i ? "+" : "", addbuf, remstr, addstr);

    if (mbuf->mb_dest & MODEBUF_DEST_CHANNEL)
      sendcmdto_channel_butserv_butone(app_source, CMD_MODE, mbuf->mb_channel, NULL, 0,
                                "%H %s%s%s%s%s%s", mbuf->mb_channel,
                                rembuf_i ? "-" : "", rembuf,
                                addbuf_i ? "+" : "", addbuf, remstr, addstr);
  }

  /* Now are we supposed to propagate to other servers? */
  if (mbuf->mb_dest & MODEBUF_DEST_SERVER) {
    /* set up parameter string */
    addstr[0] = '\0';
    addstr_i = 0;
    remstr[0] = '\0';
    remstr_i = 0;

    /*
     * limit is supressed if we're removing it; we have to figure out which
     * direction is the direction for it to be removed, though...
     */
    limitdel |= (mbuf->mb_dest & MODEBUF_DEST_HACK2) ? MODE_DEL : MODE_ADD;

    for (i = 0; i < mbuf->mb_count; i++) {
      if (MB_TYPE(mbuf, i) & MODE_SAVE)
        continue;

      if (MB_TYPE(mbuf, i) & MODE_ADD) { /* adding or removing? */
        strptr = addstr;
        strptr_i = &addstr_i;
      } else {
        strptr = remstr;
        strptr_i = &remstr_i;
      }

      /* deal with modes that take clients */
      if (MB_TYPE(mbuf, i) & (MODE_CHANOP | MODE_VOICE))
        build_string(strptr, strptr_i, NumNick(MB_CLIENT(mbuf, i)), ' ');

      /* deal with modes that take strings */
      else if (MB_TYPE(mbuf, i) & (MODE_KEY | MODE_BAN | MODE_APASS | MODE_UPASS))
        build_string(strptr, strptr_i, MB_STRING(mbuf, i), 0, ' ');

      /*
       * deal with the limit.  Logic here is complicated; if HACK2 is set,
       * we're bouncing the mode, so sense is reversed, and we have to
       * include the original limit if it looks like it's being removed
       */
      else if ((MB_TYPE(mbuf, i) & limitdel) == limitdel)
        build_string(strptr, strptr_i, limitbuf, 0, ' ');
    }

    /* we were told to deop the source */
    if (mbuf->mb_dest & MODEBUF_DEST_DEOP) {
      addbuf[addbuf_i++] = 'o'; /* remember, sense is reversed */
      addbuf[addbuf_i] = '\0'; /* terminate the string... */
      build_string(addstr, &addstr_i, NumNick(mbuf->mb_source), ' ');

      /* mark that we've done this, so we don't do it again */
      mbuf->mb_dest &= ~MODEBUF_DEST_DEOP;
    }

    if (mbuf->mb_dest & MODEBUF_DEST_OPMODE) {
      /* If OPMODE was set, we're propagating the mode as an OPMODE message */
      sendcmdto_serv_butone(mbuf->mb_source, CMD_OPMODE, mbuf->mb_connect,
                            "%H %s%s%s%s%s%s", mbuf->mb_channel,
                            rembuf_i ? "-" : "", rembuf, addbuf_i ? "+" : "",
                            addbuf, remstr, addstr);
    } else if (mbuf->mb_dest & MODEBUF_DEST_BOUNCE) {
      /*
       * If HACK2 was set, we're bouncing; we send the MODE back to the
       * connection we got it from with the senses reversed and a TS of 0;
       * origin is us
       */
      sendcmdto_one(&me, CMD_MODE, mbuf->mb_connect, "%H %s%s%s%s%s%s %Tu",
                    mbuf->mb_channel, addbuf_i ? "-" : "", addbuf,
                    rembuf_i ? "+" : "", rembuf, addstr, remstr,
                    mbuf->mb_channel->creationtime);
    } else {
      /*
       * We're propagating a normal MODE command to the rest of the network;
       * we send the actual channel TS unless this is a HACK3 or a HACK4
       */
      if (IsServer(mbuf->mb_source))
        sendcmdto_serv_butone(mbuf->mb_source, CMD_MODE, mbuf->mb_connect,
                              "%H %s%s%s%s%s%s %Tu", mbuf->mb_channel,
                              rembuf_i ? "-" : "", rembuf, addbuf_i ? "+" : "",
                              addbuf, remstr, addstr,
                              (mbuf->mb_dest & MODEBUF_DEST_HACK4) ? 0 :
                              mbuf->mb_channel->creationtime);
      else
        sendcmdto_serv_butone(mbuf->mb_source, CMD_MODE, mbuf->mb_connect,
                              "%H %s%s%s%s%s%s", mbuf->mb_channel,
                              rembuf_i ? "-" : "", rembuf, addbuf_i ? "+" : "",
                              addbuf, remstr, addstr);
    }
  }

  /* We've drained the ModeBuf... */
  mbuf->mb_add = 0;
  mbuf->mb_rem = 0;
  mbuf->mb_count = 0;

  /* reinitialize the mode-with-arg slots */
  for (i = 0; i < MAXMODEPARAMS; i++) {
    /* If we saved any, pack them down */
    if (MB_TYPE(mbuf, i) & MODE_SAVE) {
      mbuf->mb_modeargs[mbuf->mb_count] = mbuf->mb_modeargs[i];
      MB_TYPE(mbuf, mbuf->mb_count) &= ~MODE_SAVE; /* don't save anymore */

      if (mbuf->mb_count++ == i) /* don't overwrite our hard work */
        continue;
    } else if (MB_TYPE(mbuf, i) & MODE_FREE)
      MyFree(MB_STRING(mbuf, i)); /* free string if needed */

    MB_TYPE(mbuf, i) = 0;
    MB_UINT(mbuf, i) = 0;
  }

  /* If we're supposed to flush it all, do so--all hail tail recursion */
  if (all && mbuf->mb_count)
    return modebuf_flush_int(mbuf, 1);

  return 0;
}

/** Initialise a modebuf
 * This routine just initializes a ModeBuf structure with the information
 * needed and the options given.
 *
 * @param mbuf          The mode buffer to initialise.
 * @param source        The client that is performing the mode.
 * @param connect       ?
 * @param chan          The channel that the mode is being performed upon.
 * @param dest          ?
 */
void
modebuf_init(struct ModeBuf *mbuf, struct Client *source,
             struct Client *connect, struct Channel *chan, unsigned int dest)
{
  int i;

  assert(0 != mbuf);
  assert(0 != source);
  assert(0 != chan);
  assert(0 != dest);

  if (IsLocalChannel(chan->chname)) dest &= ~MODEBUF_DEST_SERVER;

  mbuf->mb_add = 0;
  mbuf->mb_rem = 0;
  mbuf->mb_source = source;
  mbuf->mb_connect = connect;
  mbuf->mb_channel = chan;
  mbuf->mb_dest = dest;
  mbuf->mb_count = 0;

  /* clear each mode-with-parameter slot */
  for (i = 0; i < MAXMODEPARAMS; i++) {
    MB_TYPE(mbuf, i) = 0;
    MB_UINT(mbuf, i) = 0;
  }
}

/** Append a new mode to a modebuf
 * This routine simply adds modes to be added or deleted; do a binary OR
 * with either MODE_ADD or MODE_DEL
 *
 * @param mbuf          Mode buffer
 * @param mode          MODE_ADD or MODE_DEL OR'd with MODE_PRIVATE etc.
 */
void
modebuf_mode(struct ModeBuf *mbuf, unsigned int mode)
{
  assert(0 != mbuf);
  assert(0 != (mode & (MODE_ADD | MODE_DEL)));

  mode &= (MODE_ADD | MODE_DEL | MODE_PRIVATE | MODE_SECRET | MODE_MODERATED |
           MODE_TOPICLIMIT | MODE_INVITEONLY | MODE_NOPRIVMSGS | MODE_REGONLY |
           MODE_DELJOINS | MODE_WASDELJOINS);

  if (!(mode & ~(MODE_ADD | MODE_DEL))) /* don't add empty modes... */
    return;

  if (mode & MODE_ADD) {
    mbuf->mb_rem &= ~mode;
    mbuf->mb_add |= mode;
  } else {
    mbuf->mb_add &= ~mode;
    mbuf->mb_rem |= mode;
  }
}

/** Append a mode that takes an int argument to the modebuf
 *
 * This routine adds a mode to be added or deleted that takes a unsigned
 * int parameter; mode may *only* be the relevant mode flag ORed with one
 * of MODE_ADD or MODE_DEL
 *
 * @param mbuf          The mode buffer to append to.
 * @param mode          The mode to append.
 * @param uint          The argument to the mode.
 */
void
modebuf_mode_uint(struct ModeBuf *mbuf, unsigned int mode, unsigned int uint)
{
  assert(0 != mbuf);
  assert(0 != (mode & (MODE_ADD | MODE_DEL)));

  if (mode == (MODE_LIMIT | MODE_DEL)) {
      mbuf->mb_rem |= mode;
      return;
  }
  MB_TYPE(mbuf, mbuf->mb_count) = mode;
  MB_UINT(mbuf, mbuf->mb_count) = uint;

  /* when we've reached the maximal count, flush the buffer */
  if (++mbuf->mb_count >=
      (MAXMODEPARAMS - (mbuf->mb_dest & MODEBUF_DEST_DEOP ? 1 : 0)))
    modebuf_flush_int(mbuf, 0);
}

/** append a string mode
 * This routine adds a mode to be added or deleted that takes a string
 * parameter; mode may *only* be the relevant mode flag ORed with one of
 * MODE_ADD or MODE_DEL
 *
 * @param mbuf          The mode buffer to append to.
 * @param mode          The mode to append.
 * @param string        The string parameter to append.
 * @param free          If the string should be free'd later.
 */
void
modebuf_mode_string(struct ModeBuf *mbuf, unsigned int mode, char *string,
                    int free)
{
  assert(0 != mbuf);
  assert(0 != (mode & (MODE_ADD | MODE_DEL)));

  MB_TYPE(mbuf, mbuf->mb_count) = mode | (free ? MODE_FREE : 0);
  MB_STRING(mbuf, mbuf->mb_count) = string;

  /* when we've reached the maximal count, flush the buffer */
  if (++mbuf->mb_count >=
      (MAXMODEPARAMS - (mbuf->mb_dest & MODEBUF_DEST_DEOP ? 1 : 0)))
    modebuf_flush_int(mbuf, 0);
}

/** Append a mode on a client to a modebuf.
 * This routine adds a mode to be added or deleted that takes a client
 * parameter; mode may *only* be the relevant mode flag ORed with one of
 * MODE_ADD or MODE_DEL
 *
 * @param mbuf          The modebuf to append the mode to.
 * @param mode          The mode to append.
 * @param client        The client argument to append.
 */
void
modebuf_mode_client(struct ModeBuf *mbuf, unsigned int mode,
                    struct Client *client)
{
  assert(0 != mbuf);
  assert(0 != (mode & (MODE_ADD | MODE_DEL)));

  MB_TYPE(mbuf, mbuf->mb_count) = mode;
  MB_CLIENT(mbuf, mbuf->mb_count) = client;

  /* when we've reached the maximal count, flush the buffer */
  if (++mbuf->mb_count >=
      (MAXMODEPARAMS - (mbuf->mb_dest & MODEBUF_DEST_DEOP ? 1 : 0)))
    modebuf_flush_int(mbuf, 0);
}

/** The exported binding for modebuf_flush()
 *
 * @param mbuf  The mode buffer to flush.
 * 
 * @see modebuf_flush_int()
 */
int
modebuf_flush(struct ModeBuf *mbuf)
{
  struct Membership *memb;

  /* Check if MODE_WASDELJOINS should be set */
  if (!(mbuf->mb_channel->mode.mode & (MODE_DELJOINS | MODE_WASDELJOINS))
      && (mbuf->mb_rem & MODE_DELJOINS)) {
    for (memb = mbuf->mb_channel->members; memb; memb = memb->next_member) {
      if (IsDelayedJoin(memb)) {
          mbuf->mb_channel->mode.mode |= MODE_WASDELJOINS;
          mbuf->mb_add |= MODE_WASDELJOINS;
          mbuf->mb_rem &= ~MODE_WASDELJOINS;
          break;
      }
    }
  }

  return modebuf_flush_int(mbuf, 1);
}

/* This extracts the simple modes contained in mbuf
 *
 * @param mbuf          The mode buffer to extract the modes from.
 * @param buf           The string buffer to write the modes into.
 */
void
modebuf_extract(struct ModeBuf *mbuf, char *buf)
{
  static int flags[] = {
/*  MODE_CHANOP,        'o', */
/*  MODE_VOICE,         'v', */
    MODE_PRIVATE,       'p',
    MODE_SECRET,        's',
    MODE_MODERATED,     'm',
    MODE_TOPICLIMIT,    't',
    MODE_INVITEONLY,    'i',
    MODE_NOPRIVMSGS,    'n',
    MODE_KEY,           'k',
    MODE_APASS,         'A',
    MODE_UPASS,         'U',
/*  MODE_BAN,           'b', */
    MODE_LIMIT,         'l',
    MODE_REGONLY,       'r',
    MODE_DELJOINS,      'D',
    0x0, 0x0
  };
  unsigned int add;
  int i, bufpos = 0, len;
  int *flag_p;
  char *key = 0, limitbuf[20];
  char *apass = 0, *upass = 0;

  assert(0 != mbuf);
  assert(0 != buf);

  buf[0] = '\0';

  add = mbuf->mb_add;

  for (i = 0; i < mbuf->mb_count; i++) { /* find keys and limits */
    if (MB_TYPE(mbuf, i) & MODE_ADD) {
      add |= MB_TYPE(mbuf, i) & (MODE_KEY | MODE_LIMIT | MODE_APASS | MODE_UPASS);

      if (MB_TYPE(mbuf, i) & MODE_KEY) /* keep strings */
        key = MB_STRING(mbuf, i);
      else if (MB_TYPE(mbuf, i) & MODE_LIMIT)
        ircd_snprintf(0, limitbuf, sizeof(limitbuf), "%u", MB_UINT(mbuf, i));
      else if (MB_TYPE(mbuf, i) & MODE_UPASS)
        upass = MB_STRING(mbuf, i);
      else if (MB_TYPE(mbuf, i) & MODE_APASS)
        apass = MB_STRING(mbuf, i);
    }
  }

  if (!add)
    return;

  buf[bufpos++] = '+'; /* start building buffer */

  for (flag_p = flags; flag_p[0]; flag_p += 2)
    if (*flag_p & add)
      buf[bufpos++] = flag_p[1];

  for (i = 0, len = bufpos; i < len; i++) {
    if (buf[i] == 'k')
      build_string(buf, &bufpos, key, 0, ' ');
    else if (buf[i] == 'l')
      build_string(buf, &bufpos, limitbuf, 0, ' ');
    else if (buf[i] == 'U')
      build_string(buf, &bufpos, upass, 0, ' ');
    else if (buf[i] == 'A')
      build_string(buf, &bufpos, apass, 0, ' ');
  }

  buf[bufpos] = '\0';

  return;
}

/** Simple function to invalidate bans
 *
 * This function sets all bans as being valid.
 *
 * @param chan  The channel to operate on.
 */
void
mode_ban_invalidate(struct Channel *chan)
{
  struct Membership *member;

  for (member = chan->members; member; member = member->next_member)
    ClearBanValid(member);
}

/** Simple function to drop invite structures
 *
 * Remove all the invites on the channel.
 *
 * @param chan          Channel to remove invites from.
 *
 */
void
mode_invite_clear(struct Channel *chan)
{
  while (chan->invites)
    del_invite(chan->invites->value.cptr, chan);
}

/* What we've done for mode_parse so far... */
#define DONE_LIMIT      0x01    /**< We've set the limit */
#define DONE_KEY        0x02    /**< We've set the key */
#define DONE_BANLIST    0x04    /**< We've sent the ban list */
#define DONE_NOTOPER    0x08    /**< We've sent a "Not oper" error */
#define DONE_BANCLEAN   0x10    /**< We've cleaned bans... */
#define DONE_UPASS      0x20    /**< We've set user pass */
#define DONE_APASS      0x40    /**< We've set admin pass */

struct ParseState {
  struct ModeBuf *mbuf;
  struct Client *cptr;
  struct Client *sptr;
  struct Channel *chptr;
  struct Membership *member;
  int parc;
  char **parv;
  unsigned int flags;
  unsigned int dir;
  unsigned int done;
  unsigned int add;
  unsigned int del;
  int args_used;
  int max_args;
  int numbans;
  struct Ban banlist[MAXPARA];
  struct {
    unsigned int flag;
    struct Client *client;
  } cli_change[MAXPARA];
};

/** Helper function to send "Not oper" or "Not member" messages
 * Here's a helper function to deal with sending along "Not oper" or
 * "Not member" messages
 *
 * @param state         Parsing State object
 */
static void
send_notoper(struct ParseState *state)
{
  if (state->done & DONE_NOTOPER)
    return;

  send_reply(state->sptr, (state->flags & MODE_PARSE_NOTOPER) ?
             ERR_CHANOPRIVSNEEDED : ERR_NOTONCHANNEL, state->chptr->chname);

  state->done |= DONE_NOTOPER;
}

/** Parse a limit
 * Helper function to convert limits
 *
 * @param state         Parsing state object.
 * @param flag_p        ?
 */
static void
mode_parse_limit(struct ParseState *state, int *flag_p)
{
  unsigned int t_limit;

  if (state->dir == MODE_ADD) { /* convert arg only if adding limit */
    if (MyUser(state->sptr) && state->max_args <= 0) /* too many args? */
      return;

    if (state->parc <= 0) { /* warn if not enough args */
      if (MyUser(state->sptr))
        need_more_params(state->sptr, "MODE +l");
      return;
    }

    t_limit = strtoul(state->parv[state->args_used++], 0, 10); /* grab arg */
    state->parc--;
    state->max_args--;

    if ((int)t_limit<0) /* don't permit a negative limit */
      return;

    if (!(state->flags & MODE_PARSE_WIPEOUT) &&
        (!t_limit || t_limit == state->chptr->mode.limit))
      return;
  } else
    t_limit = state->chptr->mode.limit;

  /* If they're not an oper, they can't change modes */
  if (state->flags & (MODE_PARSE_NOTOPER | MODE_PARSE_NOTMEMBER)) {
    send_notoper(state);
    return;
  }

  /* Can't remove a limit that's not there */
  if (state->dir == MODE_DEL && !state->chptr->mode.limit)
    return;
    
  /* Skip if this is a burst and a lower limit than this is set already */
  if ((state->flags & MODE_PARSE_BURST) &&
      (state->chptr->mode.mode & flag_p[0]) &&
      (state->chptr->mode.limit < t_limit))
    return;

  if (state->done & DONE_LIMIT) /* allow limit to be set only once */
    return;
  state->done |= DONE_LIMIT;

  if (!state->mbuf)
    return;

  modebuf_mode_uint(state->mbuf, state->dir | flag_p[0], t_limit);

  if (state->flags & MODE_PARSE_SET) { /* set the limit */
    if (state->dir & MODE_ADD) {
      state->chptr->mode.mode |= flag_p[0];
      state->chptr->mode.limit = t_limit;
    } else {
      state->chptr->mode.mode &= ~flag_p[0];
      state->chptr->mode.limit = 0;
    }
  }
}

/*
 * Helper function to convert keys
 */
static void
mode_parse_key(struct ParseState *state, int *flag_p)
{
  char *t_str, *s;
  int t_len;

  if (MyUser(state->sptr) && state->max_args <= 0) /* drop if too many args */
    return;

  if (state->parc <= 0) { /* warn if not enough args */
    if (MyUser(state->sptr))
      need_more_params(state->sptr, state->dir == MODE_ADD ? "MODE +k" :
                       "MODE -k");
    return;
  }

  t_str = state->parv[state->args_used++]; /* grab arg */
  state->parc--;
  state->max_args--;

  /* If they're not an oper, they can't change modes */
  if (state->flags & (MODE_PARSE_NOTOPER | MODE_PARSE_NOTMEMBER)) {
    send_notoper(state);
    return;
  }

  if (state->done & DONE_KEY) /* allow key to be set only once */
    return;
  state->done |= DONE_KEY;

  t_len = KEYLEN;

  /* clean up the key string */
  s = t_str;
  while (*s > ' ' && *s != ':' && *s != ',' && t_len--)
    s++;
  *s = '\0';

  if (!*t_str) { /* warn if empty */
    if (MyUser(state->sptr))
      need_more_params(state->sptr, state->dir == MODE_ADD ? "MODE +k" :
                       "MODE -k");
    return;
  }

  if (!state->mbuf)
    return;

  /* Skip if this is a burst, we have a key already and the new key is 
   * after the old one alphabetically */
  if ((state->flags & MODE_PARSE_BURST) &&
      *(state->chptr->mode.key) &&
      ircd_strcmp(state->chptr->mode.key, t_str) <= 0)
    return;

  /* can't add a key if one is set, nor can one remove the wrong key */
  if (!(state->flags & MODE_PARSE_FORCE))
    if ((state->dir == MODE_ADD && *state->chptr->mode.key) ||
        (state->dir == MODE_DEL &&
         ircd_strcmp(state->chptr->mode.key, t_str))) {
      send_reply(state->sptr, ERR_KEYSET, state->chptr->chname);
      return;
    }

  if (!(state->flags & MODE_PARSE_WIPEOUT) && state->dir == MODE_ADD &&
      !ircd_strcmp(state->chptr->mode.key, t_str))
    return; /* no key change */

  if (state->flags & MODE_PARSE_BOUNCE) {
    if (*state->chptr->mode.key) /* reset old key */
      modebuf_mode_string(state->mbuf, MODE_DEL | flag_p[0],
                          state->chptr->mode.key, 0);
    else /* remove new bogus key */
      modebuf_mode_string(state->mbuf, MODE_ADD | flag_p[0], t_str, 0);
  } else /* send new key */
    modebuf_mode_string(state->mbuf, state->dir | flag_p[0], t_str, 0);

  if (state->flags & MODE_PARSE_SET) {
    if (state->dir == MODE_ADD) /* set the new key */
      ircd_strncpy(state->chptr->mode.key, t_str, KEYLEN);
    else /* remove the old key */
      *state->chptr->mode.key = '\0';
  }
}

/*
 * Helper function to convert user passes
 */
static void
mode_parse_upass(struct ParseState *state, int *flag_p)
{
  char *t_str, *s;
  int t_len;

  if (MyUser(state->sptr) && state->max_args <= 0) /* drop if too many args */
    return;

  if (state->parc <= 0) { /* warn if not enough args */
    if (MyUser(state->sptr))
      need_more_params(state->sptr, state->dir == MODE_ADD ? "MODE +U" :
                       "MODE -U");
    return;
  }

  t_str = state->parv[state->args_used++]; /* grab arg */
  state->parc--;
  state->max_args--;

  /* If they're not an oper, they can't change modes */
  if (state->flags & (MODE_PARSE_NOTOPER | MODE_PARSE_NOTMEMBER)) {
    send_notoper(state);
    return;
  }

  /* If a non-service user is trying to force it, refuse. */
  if (state->flags & MODE_PARSE_FORCE && MyUser(state->sptr)
      && !HasPriv(state->sptr, PRIV_APASS_OPMODE)) {
    send_reply(state->sptr, ERR_NOTMANAGER, state->chptr->chname,
               state->chptr->chname);
    return;
  }

  /* If they are not the channel manager, they are not allowed to change it */
  if (MyUser(state->sptr) && !(state->flags & MODE_PARSE_FORCE || IsChannelManager(state->member))) {
    if (*state->chptr->mode.apass) {
      send_reply(state->sptr, ERR_NOTMANAGER, state->chptr->chname,
                 state->chptr->chname);
    } else if (TStime() - state->chptr->creationtime >= 171000) {
      send_reply(state->sptr, ERR_NOMANAGER_LONG, state->chptr->chname);
    } else {
      send_reply(state->sptr, ERR_NOMANAGER_SHORT, state->chptr->chname);
    }
    return;
  }

  if (state->done & DONE_UPASS) /* allow upass to be set only once */
    return;
  state->done |= DONE_UPASS;

  t_len = PASSLEN + 1;

  /* clean up the upass string */
  s = t_str;
  while (*++s > ' ' && *s != ':' && --t_len)
    ;
  *s = '\0';

  if (!*t_str) { /* warn if empty */
    if (MyUser(state->sptr))
      need_more_params(state->sptr, state->dir == MODE_ADD ? "MODE +U" :
                       "MODE -U");
    return;
  }

  if (!state->mbuf)
    return;

  if (!(state->flags & MODE_PARSE_FORCE)) {
    /* can't add the upass while apass is not set */
    if (state->dir == MODE_ADD && !*state->chptr->mode.apass) {
      send_reply(state->sptr, ERR_UPASSNOTSET, state->chptr->chname, state->chptr->chname);
      return;
    }
    /* cannot set a +U password that is the same as +A */
    if (state->dir == MODE_ADD && !ircd_strcmp(state->chptr->mode.apass, t_str)) {
      send_reply(state->sptr, ERR_UPASS_SAME_APASS, state->chptr->chname);
      return;
    }
    /* can't add a upass if one is set, nor can one remove the wrong upass */
    if ((state->dir == MODE_ADD && *state->chptr->mode.upass) ||
        (state->dir == MODE_DEL &&
         ircd_strcmp(state->chptr->mode.upass, t_str))) {
      send_reply(state->sptr, ERR_KEYSET, state->chptr->chname);
      return;
    }
  }

  if (!(state->flags & MODE_PARSE_WIPEOUT) && state->dir == MODE_ADD &&
      !ircd_strcmp(state->chptr->mode.upass, t_str))
    return; /* no upass change */

  if (state->flags & MODE_PARSE_BOUNCE) {
    if (*state->chptr->mode.upass) /* reset old upass */
      modebuf_mode_string(state->mbuf, MODE_DEL | flag_p[0],
                          state->chptr->mode.upass, 0);
    else /* remove new bogus upass */
      modebuf_mode_string(state->mbuf, MODE_ADD | flag_p[0], t_str, 0);
  } else /* send new upass */
    modebuf_mode_string(state->mbuf, state->dir | flag_p[0], t_str, 0);

  if (state->flags & MODE_PARSE_SET) {
    if (state->dir == MODE_ADD) /* set the new upass */
      ircd_strncpy(state->chptr->mode.upass, t_str, PASSLEN);
    else /* remove the old upass */
      *state->chptr->mode.upass = '\0';
  }
}

/*
 * Helper function to convert admin passes
 */
static void
mode_parse_apass(struct ParseState *state, int *flag_p)
{
  char *t_str, *s;
  int t_len;

  if (MyUser(state->sptr) && state->max_args <= 0) /* drop if too many args */
    return;

  if (state->parc <= 0) { /* warn if not enough args */
    if (MyUser(state->sptr))
      need_more_params(state->sptr, state->dir == MODE_ADD ? "MODE +A" :
                       "MODE -A");
    return;
  }

  t_str = state->parv[state->args_used++]; /* grab arg */
  state->parc--;
  state->max_args--;

  /* If they're not an oper, they can't change modes */
  if (state->flags & (MODE_PARSE_NOTOPER | MODE_PARSE_NOTMEMBER)) {
    send_notoper(state);
    return;
  }

  /* If a non-service user is trying to force it, refuse. */
  if (state->flags & MODE_PARSE_FORCE && MyUser(state->sptr)
      && !HasPriv(state->sptr, PRIV_APASS_OPMODE)) {
    send_reply(state->sptr, ERR_NOTMANAGER, state->chptr->chname,
               state->chptr->chname);
    return;
  }

  /* Don't allow to change the Apass if the channel is older than 48 hours. */
  if (TStime() - state->chptr->creationtime >= 172800 && !IsAnOper(state->sptr)) {
    send_reply(state->sptr, ERR_CHANSECURED, state->chptr->chname);
    return;
  }

  /* If they are not the channel manager, they are not allowed to change it */
  if (MyUser(state->sptr) && !(state->flags & MODE_PARSE_FORCE || IsChannelManager(state->member))) {
    if (*state->chptr->mode.apass) {
      send_reply(state->sptr, ERR_NOTMANAGER, state->chptr->chname,
                 state->chptr->chname);
    } else if (TStime() - state->chptr->creationtime >= 171000) {
      send_reply(state->sptr, ERR_NOMANAGER_LONG, state->chptr->chname);
    } else {
      send_reply(state->sptr, ERR_NOMANAGER_SHORT, state->chptr->chname);
    }
    return;
  }

  if (state->done & DONE_APASS) /* allow apass to be set only once */
    return;
  state->done |= DONE_APASS;

  t_len = PASSLEN + 1;

  /* clean up the apass string */
  s = t_str;
  while (*++s > ' ' && *s != ':' && --t_len)
    ;
  *s = '\0';

  if (!*t_str) { /* warn if empty */
    if (MyUser(state->sptr))
      need_more_params(state->sptr, state->dir == MODE_ADD ? "MODE +A" :
                       "MODE -A");
    return;
  }

  if (!state->mbuf)
    return;

  if (!(state->flags & MODE_PARSE_FORCE)) {
    /* can't remove the apass while upass is still set */
    if (state->dir == MODE_DEL && *state->chptr->mode.upass) {
      send_reply(state->sptr, ERR_UPASSSET, state->chptr->chname, state->chptr->chname);
      return;
    }
    /* can't add an apass if one is set, nor can one remove the wrong apass */
    if ((state->dir == MODE_ADD && *state->chptr->mode.apass) ||
        (state->dir == MODE_DEL && ircd_strcmp(state->chptr->mode.apass, t_str))) {
      send_reply(state->sptr, ERR_KEYSET, state->chptr->chname);
      return;
    }
  }

  if (!(state->flags & MODE_PARSE_WIPEOUT) && state->dir == MODE_ADD &&
      !ircd_strcmp(state->chptr->mode.apass, t_str))
    return; /* no apass change */

  if (state->flags & MODE_PARSE_BOUNCE) {
    if (*state->chptr->mode.apass) /* reset old apass */
      modebuf_mode_string(state->mbuf, MODE_DEL | flag_p[0],
                          state->chptr->mode.apass, 0);
    else /* remove new bogus apass */
      modebuf_mode_string(state->mbuf, MODE_ADD | flag_p[0], t_str, 0);
  } else /* send new apass */
    modebuf_mode_string(state->mbuf, state->dir | flag_p[0], t_str, 0);

  if (state->flags & MODE_PARSE_SET) {
    if (state->dir == MODE_ADD) { /* set the new apass */
      /* Make it VERY clear to the user that this is a one-time password */
      ircd_strncpy(state->chptr->mode.apass, t_str, PASSLEN);
      if (MyUser(state->sptr)) {
        send_reply(state->sptr, RPL_APASSWARN_SET, state->chptr->mode.apass);
        send_reply(state->sptr, RPL_APASSWARN_SECRET, state->chptr->chname,
                   state->chptr->mode.apass);
      }
    } else { /* remove the old apass */
      *state->chptr->mode.apass = '\0';
      if (MyUser(state->sptr))
        send_reply(state->sptr, RPL_APASSWARN_CLEAR);
    }
  }
}

/** Compare one ban's extent to another.
 * This works very similarly to mmatch() but it knows about CIDR masks
 * and ban exceptions.  If both bans are CIDR-based, compare their
 * address bits; otherwise, use mmatch().
 * @param[in] old_ban One ban.
 * @param[in] new_ban Another ban.
 * @return Zero if \a old_ban is a superset of \a new_ban, non-zero otherwise.
 */
static int
bmatch(struct Ban *old_ban, struct Ban *new_ban)
{
  int res;
  assert(old_ban != NULL);
  assert(new_ban != NULL);
  /* A ban is never treated as a superset of an exception. */
  if (!(old_ban->flags & BAN_EXCEPTION)
      && (new_ban->flags & BAN_EXCEPTION))
    return 1;
  /* If either is not an address mask, match the text masks. */
  if ((old_ban->flags & new_ban->flags & BAN_IPMASK) == 0)
    return mmatch(old_ban->banstr, new_ban->banstr);
  /* If the old ban has a longer prefix than new, it cannot be a superset. */
  if (old_ban->addrbits > new_ban->addrbits)
    return 1;
  /* Compare the masks before the hostname part.  */
  old_ban->banstr[old_ban->nu_len] = new_ban->banstr[new_ban->nu_len] = '\0';
  res = mmatch(old_ban->banstr, new_ban->banstr);
  old_ban->banstr[old_ban->nu_len] = new_ban->banstr[new_ban->nu_len] = '@';
  if (res)
    return res;
  /* Compare the addresses. */
  return !ipmask_check(&new_ban->address, &old_ban->address, old_ban->addrbits);
}

/** Add a ban from a ban list and mark bans that should be removed
 * because they overlap.
 *
 * There are three invariants for a ban list.  First, no ban may be
 * more specific than another ban.  Second, no exception may be more
 * specific than another exception.  Finally, no ban may be more
 * specific than any exception.
 *
 * @param[in,out] banlist Pointer to head of list.
 * @param[in] newban Ban (or exception) to add (or remove).
 * @param[in] do_free If non-zero, free \a newban on failure.
 * @return Zero if \a newban could be applied, non-zero if not.
 */
int apply_ban(struct Ban **banlist, struct Ban *newban, int do_free)
{
  struct Ban *ban;
  size_t count = 0;

  assert(newban->flags & (BAN_ADD|BAN_DEL));
  if (newban->flags & BAN_ADD) {
    size_t totlen = 0;
    /* If a less specific entry is found, fail.  */
    for (ban = *banlist; ban; ban = ban->next) {
      if (!bmatch(ban, newban)) {
        if (do_free)
          free_ban(newban);
        else
          MyFree(newban->banstr);
        return 1;
      }
      if (!(ban->flags & (BAN_OVERLAPPED|BAN_DEL))) {
        count++;
        totlen += strlen(ban->banstr);
      }
    }
    /* Mark more specific entries and add this one to the end of the list. */
    while ((ban = *banlist) != NULL) {
      if (!bmatch(newban, ban)) {
        ban->flags |= BAN_OVERLAPPED | BAN_DEL;
      }
      banlist = &ban->next;
    }
    *banlist = newban;
    return 0;
  } else if (newban->flags & BAN_DEL) {
    size_t remove_count = 0;
    /* Mark more specific entries. */
    for (ban = *banlist; ban; ban = ban->next) {
      if (!bmatch(newban, ban)) {
        ban->flags |= BAN_OVERLAPPED | BAN_DEL;
        remove_count++;
      }
    }
    if (remove_count)
        return 0;
    /* If no matches were found, fail. */
    if (do_free)
      free_ban(newban);
    else
      MyFree(newban->banstr);
    return 3;
  }
  if (do_free)
    free_ban(newban);
  else
    MyFree(newban->banstr);
  return 4;
}

/*
 * Helper function to convert bans
 */
static void
mode_parse_ban(struct ParseState *state, int *flag_p)
{
  char *t_str, *s;
  struct Ban *ban, *newban;

  if (state->parc <= 0) { /* Not enough args, send ban list */
    if (MyUser(state->sptr) && !(state->done & DONE_BANLIST)) {
      send_ban_list(state->sptr, state->chptr);
      state->done |= DONE_BANLIST;
    }

    return;
  }

  if (MyUser(state->sptr) && state->max_args <= 0) /* drop if too many args */
    return;

  t_str = state->parv[state->args_used++]; /* grab arg */
  state->parc--;
  state->max_args--;

  /* If they're not an oper, they can't change modes */
  if (state->flags & (MODE_PARSE_NOTOPER | MODE_PARSE_NOTMEMBER)) {
    send_notoper(state);
    return;
  }

  if ((s = strchr(t_str, ' ')))
    *s = '\0';

  if (!*t_str || *t_str == ':') { /* warn if empty */
    if (MyUser(state->sptr))
      need_more_params(state->sptr, state->dir == MODE_ADD ? "MODE +b" :
                       "MODE -b");
    return;
  }

  /* Clear all ADD/DEL/OVERLAPPED flags from ban list. */
  if (!(state->done & DONE_BANCLEAN)) {
    for (ban = state->chptr->banlist; ban; ban = ban->next)
      ban->flags &= ~(BAN_ADD | BAN_DEL | BAN_OVERLAPPED);
    state->done |= DONE_BANCLEAN;
  }

  /* remember the ban for the moment... */
  newban = state->banlist + (state->numbans++);
  newban->next = 0;
  newban->flags = ((state->dir == MODE_ADD) ? BAN_ADD : BAN_DEL)
      | (*flag_p == MODE_BAN ? 0 : BAN_EXCEPTION);
  newban->banstr = NULL;
  set_ban_mask(newban, collapse(pretty_mask(t_str)));
  newban->who = cli_name(state->sptr);
  newban->when = TStime();
  apply_ban(&state->chptr->banlist, newban, 0);
}

/*
 * This is the bottom half of the ban processor
 */
static void
mode_process_bans(struct ParseState *state)
{
  struct Ban *ban, *newban, *prevban, *nextban;
  int count = 0;
  int len = 0;
  int banlen;
  int changed = 0;

  for (prevban = 0, ban = state->chptr->banlist; ban; ban = nextban) {
    count++;
    banlen = strlen(ban->banstr);
    len += banlen;
    nextban = ban->next;

    if ((ban->flags & (BAN_DEL | BAN_ADD)) == (BAN_DEL | BAN_ADD)) {
      if (prevban)
        prevban->next = 0; /* Break the list; ban isn't a real ban */
      else
        state->chptr->banlist = 0;

      count--;
      len -= banlen;

      MyFree(ban->banstr);

      continue;
    } else if (ban->flags & BAN_DEL) { /* Deleted a ban? */
      modebuf_mode_string(state->mbuf, MODE_DEL | MODE_BAN,
                          ban->banstr, 1);

      if (state->flags & MODE_PARSE_SET) { /* Ok, make it take effect */
        if (prevban) /* clip it out of the list... */
          prevban->next = ban->next;
        else
          state->chptr->banlist = ban->next;

        count--;
        len -= banlen;

        ban->banstr = NULL; /* modebuf_mode_string() gave ownership of
                             * the ban string to state->mbuf */
        free_ban(ban);

        changed++;
        continue; /* next ban; keep prevban like it is */
      } else
        ban->flags &= BAN_IPMASK; /* unset other flags */
    } else if (ban->flags & BAN_ADD) { /* adding a ban? */
      if (prevban)
        prevban->next = 0; /* Break the list; ban isn't a real ban */
      else
        state->chptr->banlist = 0;

      /* If we're supposed to ignore it, do so. */
      if (ban->flags & BAN_OVERLAPPED &&
          !(state->flags & MODE_PARSE_BOUNCE)) {
        count--;
        len -= banlen;
        MyFree(ban->banstr);
      } else {
        if (state->flags & MODE_PARSE_SET && MyUser(state->sptr) &&
            (len > (feature_int(FEAT_AVBANLEN) * feature_int(FEAT_MAXBANS)) ||
             count > feature_int(FEAT_MAXBANS))) {
          send_reply(state->sptr, ERR_BANLISTFULL, state->chptr->chname,
                     ban->banstr);
          count--;
          len -= banlen;
          MyFree(ban->banstr);
        } else {
          /* add the ban to the buffer */
          modebuf_mode_string(state->mbuf, MODE_ADD | MODE_BAN,
                              ban->banstr, 1);

          if (state->flags & MODE_PARSE_SET) { /* create a new ban */
            newban = make_ban(ban->banstr);
            DupString(newban->who, ban->who);
            newban->when = ban->when;
            newban->flags = ban->flags & BAN_IPMASK;

            newban->next = state->chptr->banlist; /* and link it in */
            state->chptr->banlist = newban;

            changed++;
          }
        }
      }
    }

    prevban = ban;
  } /* for (prevban = 0, ban = state->chptr->banlist; ban; ban = nextban) { */

  /* Release all masks of removed bans */
  for (count = 0; count < state->numbans; ++count) {
    ban = state->banlist + count;
    if (ban->flags & BAN_DEL)
      MyFree(ban->banstr);
  }

  if (changed) /* if we changed the ban list, we must invalidate the bans */
    mode_ban_invalidate(state->chptr);
}

/*
 * Helper function to process client changes
 */
static void
mode_parse_client(struct ParseState *state, int *flag_p)
{
  char *t_str;
  struct Client *acptr;
  int i;

  if (MyUser(state->sptr) && state->max_args <= 0) /* drop if too many args */
    return;

  if (state->parc <= 0) /* return if not enough args */
    return;

  t_str = state->parv[state->args_used++]; /* grab arg */
  state->parc--;
  state->max_args--;

  /* If they're not an oper, they can't change modes */
  if (state->flags & (MODE_PARSE_NOTOPER | MODE_PARSE_NOTMEMBER)) {
    send_notoper(state);
    return;
  }

  if (MyUser(state->sptr)) /* find client we're manipulating */
    acptr = find_chasing(state->sptr, t_str, NULL);
  else
    acptr = findNUser(t_str);

  if (!acptr)
    return; /* find_chasing() already reported an error to the user */

  for (i = 0; i < MAXPARA; i++) /* find an element to stick them in */
    if (!state->cli_change[i].flag || (state->cli_change[i].client == acptr &&
                                       state->cli_change[i].flag & flag_p[0]))
      break; /* found a slot */

  /* Store what we're doing to them */
  state->cli_change[i].flag = state->dir | flag_p[0];
  state->cli_change[i].client = acptr;
}

/*
 * Helper function to process the changed client list
 */
static void
mode_process_clients(struct ParseState *state)
{
  int i;
  struct Membership *member;

  for (i = 0; state->cli_change[i].flag; i++) {
    assert(0 != state->cli_change[i].client);

    /* look up member link */
    if (!(member = find_member_link(state->chptr,
                                    state->cli_change[i].client)) ||
        (MyUser(state->sptr) && IsZombie(member))) {
      if (MyUser(state->sptr))
        send_reply(state->sptr, ERR_USERNOTINCHANNEL,
                   cli_name(state->cli_change[i].client),
                   state->chptr->chname);
      continue;
    }

    if ((state->cli_change[i].flag & MODE_ADD &&
         (state->cli_change[i].flag & member->status)) ||
        (state->cli_change[i].flag & MODE_DEL &&
         !(state->cli_change[i].flag & member->status)))
      continue; /* no change made, don't do anything */

    /* see if the deop is allowed */
    if ((state->cli_change[i].flag & (MODE_DEL | MODE_CHANOP)) ==
        (MODE_DEL | MODE_CHANOP)) {
      /* prevent +k users from being deopped */
      if (IsChannelService(state->cli_change[i].client)) {
        if (state->flags & MODE_PARSE_FORCE) /* it was forced */
          sendto_opmask_butone(0, SNO_HACK4, "Deop of +k user on %H by %s",
                               state->chptr,
                               (IsServer(state->sptr) ? cli_name(state->sptr) :
                                cli_name((cli_user(state->sptr))->server)));

        else if (MyUser(state->sptr) && state->flags & MODE_PARSE_SET) {
          send_reply(state->sptr, ERR_ISCHANSERVICE,
                     cli_name(state->cli_change[i].client),
                     state->chptr->chname);
          continue;
        }
      }

      /* check deop for local user */
      if (MyUser(state->sptr)) {

        /* don't allow local opers to be deopped on local channels */
        if (state->cli_change[i].client != state->sptr &&
            IsLocalChannel(state->chptr->chname) &&
            HasPriv(state->cli_change[i].client, PRIV_DEOP_LCHAN)) {
          send_reply(state->sptr, ERR_ISOPERLCHAN,
                     cli_name(state->cli_change[i].client),
                     state->chptr->chname);
          continue;
        }

        /* don't allow to deop members with an op level that is <= our own level */
        if (state->sptr != state->cli_change[i].client          /* but allow to deop oneself */
            && state->chptr->mode.apass[0]
            && state->member
            && OpLevel(member) <= OpLevel(state->member)) {
            int equal = (OpLevel(member) == OpLevel(state->member));
            send_reply(state->sptr, ERR_NOTLOWEROPLEVEL,
                       cli_name(state->cli_change[i].client),
                       state->chptr->chname,
                       OpLevel(state->member), OpLevel(member),
                       "deop", equal ? "the same" : "a higher");
          continue;
        }
    }
    }

    /* set op-level of member being opped */
    if ((state->cli_change[i].flag & (MODE_ADD | MODE_CHANOP)) ==
        (MODE_ADD | MODE_CHANOP)) {
      /* If being opped by an outsider, get oplevel 0 for an apass
       *   channel, else MAXOPLEVEL.
       * Otherwise, if not an apass channel, or state->member has
       *   MAXOPLEVEL, get oplevel MAXOPLEVEL.
       * Otherwise, get state->member's oplevel+1.
       */
      if (!state->member)
        SetOpLevel(member, state->chptr->mode.apass[0] ? 0 : MAXOPLEVEL);
      else if (!state->chptr->mode.apass[0] || OpLevel(state->member) == MAXOPLEVEL)
        SetOpLevel(member, MAXOPLEVEL);
      else
        SetOpLevel(member, OpLevel(state->member) + 1);
    }

    /* actually effect the change */
    if (state->flags & MODE_PARSE_SET) {
      if (state->cli_change[i].flag & MODE_ADD) {
        if (IsDelayedJoin(member))
          RevealDelayedJoin(member);
        member->status |= (state->cli_change[i].flag &
                           (MODE_CHANOP | MODE_VOICE));
        if (state->cli_change[i].flag & MODE_CHANOP)
          ClearDeopped(member);
      } else
        member->status &= ~(state->cli_change[i].flag &
                            (MODE_CHANOP | MODE_VOICE));
    }

    /* accumulate the change */
    modebuf_mode_client(state->mbuf, state->cli_change[i].flag,
                        state->cli_change[i].client);
  } /* for (i = 0; state->cli_change[i].flags; i++) */
}

/*
 * Helper function to process the simple modes
 */
static void
mode_parse_mode(struct ParseState *state, int *flag_p)
{
  /* If they're not an oper, they can't change modes */
  if (state->flags & (MODE_PARSE_NOTOPER | MODE_PARSE_NOTMEMBER)) {
    send_notoper(state);
    return;
  }

  if (!state->mbuf)
    return;

  if (state->dir == MODE_ADD) {
    state->add |= flag_p[0];
    state->del &= ~flag_p[0];

    if (flag_p[0] & MODE_SECRET) {
      state->add &= ~MODE_PRIVATE;
      state->del |= MODE_PRIVATE;
    } else if (flag_p[0] & MODE_PRIVATE) {
      state->add &= ~MODE_SECRET;
      state->del |= MODE_SECRET;
    }
    if (flag_p[0] & MODE_DELJOINS) {
      state->add &= ~MODE_WASDELJOINS;
      state->del |= MODE_WASDELJOINS;
    }
  } else {
    state->add &= ~flag_p[0];
    state->del |= flag_p[0];
  }

  assert(0 == (state->add & state->del));
  assert((MODE_SECRET | MODE_PRIVATE) !=
         (state->add & (MODE_SECRET | MODE_PRIVATE)));
}

/*
 * This routine is intended to parse MODE or OPMODE commands and effect the
 * changes (or just build the bounce buffer).  We pass the starting offset
 * as a 
 */
int
mode_parse(struct ModeBuf *mbuf, struct Client *cptr, struct Client *sptr,
           struct Channel *chptr, int parc, char *parv[], unsigned int flags,
           struct Membership* member)
{
  static int chan_flags[] = {
    MODE_CHANOP,        'o',
    MODE_VOICE,         'v',
    MODE_PRIVATE,       'p',
    MODE_SECRET,        's',
    MODE_MODERATED,     'm',
    MODE_TOPICLIMIT,    't',
    MODE_INVITEONLY,    'i',
    MODE_NOPRIVMSGS,    'n',
    MODE_KEY,           'k',
    MODE_APASS,         'A',
    MODE_UPASS,         'U',
    MODE_BAN,           'b',
    MODE_LIMIT,         'l',
    MODE_REGONLY,       'r',
    MODE_DELJOINS,      'D',
    MODE_ADD,           '+',
    MODE_DEL,           '-',
    0x0, 0x0
  };
  int i;
  int *flag_p;
  unsigned int t_mode;
  char *modestr;
  struct ParseState state;

  assert(0 != cptr);
  assert(0 != sptr);
  assert(0 != chptr);
  assert(0 != parc);
  assert(0 != parv);

  state.mbuf = mbuf;
  state.cptr = cptr;
  state.sptr = sptr;
  state.chptr = chptr;
  state.member = member;
  state.parc = parc;
  state.parv = parv;
  state.flags = flags;
  state.dir = MODE_ADD;
  state.done = 0;
  state.add = 0;
  state.del = 0;
  state.args_used = 0;
  state.max_args = MAXMODEPARAMS;
  state.numbans = 0;

  for (i = 0; i < MAXPARA; i++) { /* initialize ops/voices arrays */
    state.banlist[i].next = 0;
    state.banlist[i].who = 0;
    state.banlist[i].when = 0;
    state.banlist[i].flags = 0;
    state.cli_change[i].flag = 0;
    state.cli_change[i].client = 0;
  }

  modestr = state.parv[state.args_used++];
  state.parc--;

  while (*modestr) {
    for (; *modestr; modestr++) {
      for (flag_p = chan_flags; flag_p[0]; flag_p += 2) /* look up flag */
        if (flag_p[1] == *modestr)
          break;

      if (!flag_p[0]) { /* didn't find it?  complain and continue */
        if (MyUser(state.sptr))
          send_reply(state.sptr, ERR_UNKNOWNMODE, *modestr);
        continue;
      }

      switch (*modestr) {
      case '+': /* switch direction to MODE_ADD */
      case '-': /* switch direction to MODE_DEL */
        state.dir = flag_p[0];
        break;

      case 'l': /* deal with limits */
        mode_parse_limit(&state, flag_p);
        break;

      case 'k': /* deal with keys */
        mode_parse_key(&state, flag_p);
        break;

      case 'A': /* deal with Admin passes */
        if (feature_bool(FEAT_OPLEVELS))
        mode_parse_apass(&state, flag_p);
        break;

      case 'U': /* deal with user passes */
        if (feature_bool(FEAT_OPLEVELS))
        mode_parse_upass(&state, flag_p);
        break;

      case 'b': /* deal with bans */
        mode_parse_ban(&state, flag_p);
        break;

      case 'o': /* deal with ops/voice */
      case 'v':
        mode_parse_client(&state, flag_p);
        break;

      default: /* deal with other modes */
        mode_parse_mode(&state, flag_p);
        break;
      } /* switch (*modestr) */
    } /* for (; *modestr; modestr++) */

    if (state.flags & MODE_PARSE_BURST)
      break; /* don't interpret any more arguments */

    if (state.parc > 0) { /* process next argument in string */
      modestr = state.parv[state.args_used++];
      state.parc--;

      /* is it a TS? */
      if (IsServer(state.sptr) && !state.parc && IsDigit(*modestr)) {
        time_t recv_ts;

        if (!(state.flags & MODE_PARSE_SET))      /* don't set earlier TS if */
          break;                     /* we're then going to bounce the mode! */

        recv_ts = atoi(modestr);

        if (recv_ts && recv_ts < state.chptr->creationtime)
          state.chptr->creationtime = recv_ts; /* respect earlier TS */

        break; /* break out of while loop */
      } else if (state.flags & MODE_PARSE_STRICT ||
                 (MyUser(state.sptr) && state.max_args <= 0)) {
        state.parc++; /* we didn't actually gobble the argument */
        state.args_used--;
        break; /* break out of while loop */
      }
    }
  } /* while (*modestr) */

  /*
   * the rest of the function finishes building resultant MODEs; if the
   * origin isn't a member or an oper, skip it.
   */
  if (!state.mbuf || state.flags & (MODE_PARSE_NOTOPER | MODE_PARSE_NOTMEMBER))
    return state.args_used; /* tell our parent how many args we gobbled */

  t_mode = state.chptr->mode.mode;

  if (state.del & t_mode) { /* delete any modes to be deleted... */
    modebuf_mode(state.mbuf, MODE_DEL | (state.del & t_mode));

    t_mode &= ~state.del;
  }
  if (state.add & ~t_mode) { /* add any modes to be added... */
    modebuf_mode(state.mbuf, MODE_ADD | (state.add & ~t_mode));

    t_mode |= state.add;
  }

  if (state.flags & MODE_PARSE_SET) { /* set the channel modes */
    if ((state.chptr->mode.mode & MODE_INVITEONLY) &&
        !(t_mode & MODE_INVITEONLY))
      mode_invite_clear(state.chptr);

    state.chptr->mode.mode = t_mode;
  }

  if (state.flags & MODE_PARSE_WIPEOUT) {
    if (state.chptr->mode.limit && !(state.done & DONE_LIMIT))
      modebuf_mode_uint(state.mbuf, MODE_DEL | MODE_LIMIT,
                        state.chptr->mode.limit);
    if (*state.chptr->mode.key && !(state.done & DONE_KEY))
      modebuf_mode_string(state.mbuf, MODE_DEL | MODE_KEY,
                          state.chptr->mode.key, 0);
    if (*state.chptr->mode.upass && !(state.done & DONE_UPASS))
      modebuf_mode_string(state.mbuf, MODE_DEL | MODE_UPASS,
                          state.chptr->mode.upass, 0);
    if (*state.chptr->mode.apass && !(state.done & DONE_APASS))
      modebuf_mode_string(state.mbuf, MODE_DEL | MODE_APASS,
                          state.chptr->mode.apass, 0);
  }

  if (state.done & DONE_BANCLEAN) /* process bans */
    mode_process_bans(&state);

  /* process client changes */
  if (state.cli_change[0].flag)
    mode_process_clients(&state);

  return state.args_used; /* tell our parent how many args we gobbled */
}

/*
 * Initialize a join buffer
 */
void
joinbuf_init(struct JoinBuf *jbuf, struct Client *source,
             struct Client *connect, unsigned int type, char *comment,
             time_t create)
{
  int i;

  assert(0 != jbuf);
  assert(0 != source);
  assert(0 != connect);

  jbuf->jb_source = source; /* just initialize struct JoinBuf */
  jbuf->jb_connect = connect;
  jbuf->jb_type = type;
  jbuf->jb_comment = comment;
  jbuf->jb_create = create;
  jbuf->jb_count = 0;
  jbuf->jb_strlen = (((type == JOINBUF_TYPE_JOIN ||
                       type == JOINBUF_TYPE_PART ||
                       type == JOINBUF_TYPE_PARTALL) ?
                      STARTJOINLEN : STARTCREATELEN) +
                     (comment ? strlen(comment) + 2 : 0));

  for (i = 0; i < MAXJOINARGS; i++)
    jbuf->jb_channels[i] = 0;
}

/*
 * Add a channel to the join buffer
 */
void
joinbuf_join(struct JoinBuf *jbuf, struct Channel *chan, unsigned int flags)
{
  unsigned int len;
  int is_local;

  assert(0 != jbuf);

  if (!chan) {
    if (jbuf->jb_type == JOINBUF_TYPE_JOIN)
      sendcmdto_serv_butone(jbuf->jb_source, CMD_JOIN, jbuf->jb_connect, "0");

    return;
  }

  is_local = IsLocalChannel(chan->chname);

  if (jbuf->jb_type == JOINBUF_TYPE_PART ||
      jbuf->jb_type == JOINBUF_TYPE_PARTALL) {
    struct Membership *member = find_member_link(chan, jbuf->jb_source);
    if (IsUserParting(member))
      return;
    SetUserParting(member);

    /* Send notification to channel */
    if (!(flags & (CHFL_ZOMBIE | CHFL_DELAYED)))
      sendcmdto_channel_butserv_butone(jbuf->jb_source, CMD_PART, chan, NULL, 0,
                                (flags & CHFL_BANNED || !jbuf->jb_comment) ?
                                ":%H" : "%H :%s", chan, jbuf->jb_comment);
    else if (MyUser(jbuf->jb_source))
      sendcmdto_one(jbuf->jb_source, CMD_PART, jbuf->jb_source,
                    (flags & CHFL_BANNED || !jbuf->jb_comment) ?
                    ":%H" : "%H :%s", chan, jbuf->jb_comment);
    /* XXX: Shouldn't we send a PART here anyway? */
    /* to users on the channel?  Why?  From their POV, the user isn't on
     * the channel anymore anyway.  We don't send to servers until below,
     * when we gang all the channel parts together.  Note that this is
     * exactly the same logic, albeit somewhat more concise, as was in
     * the original m_part.c */

    if (jbuf->jb_type == JOINBUF_TYPE_PARTALL ||
        is_local) /* got to remove user here */
      remove_user_from_channel(jbuf->jb_source, chan);
  } else {
    int oplevel = chan->mode.apass[0] ? 0 : MAXOPLEVEL;
    /* Add user to channel */
    if ((chan->mode.mode & MODE_DELJOINS) && !(flags & CHFL_VOICED_OR_OPPED))
      add_user_to_channel(chan, jbuf->jb_source, flags | CHFL_DELAYED, oplevel);
    else
      add_user_to_channel(chan, jbuf->jb_source, flags, oplevel);

    /* send notification to all servers */
    if (jbuf->jb_type != JOINBUF_TYPE_CREATE && !is_local)
      sendcmdto_serv_butone(jbuf->jb_source, CMD_JOIN, jbuf->jb_connect,
                            "%H %Tu", chan, chan->creationtime);

    if (!((chan->mode.mode & MODE_DELJOINS) && !(flags & CHFL_VOICED_OR_OPPED))) {
      /* Send the notification to the channel */
      sendcmdto_channel_butserv_butone(jbuf->jb_source, CMD_JOIN, chan, NULL, 0, "%H", chan);

      /* send an op, too, if needed */
      if (!MyUser(jbuf->jb_source) && jbuf->jb_type == JOINBUF_TYPE_CREATE)
        sendcmdto_channel_butserv_butone(jbuf->jb_source, CMD_MODE, chan, NULL, 0, "%H +o %C",
                                         chan, jbuf->jb_source);
    } else if (MyUser(jbuf->jb_source))
      sendcmdto_one(jbuf->jb_source, CMD_JOIN, jbuf->jb_source, ":%H", chan);
  }

  if (jbuf->jb_type == JOINBUF_TYPE_PARTALL ||
      jbuf->jb_type == JOINBUF_TYPE_JOIN || is_local)
    return; /* don't send to remote */

  /* figure out if channel name will cause buffer to be overflowed */
  len = chan ? strlen(chan->chname) + 1 : 2;
  if (jbuf->jb_strlen + len > BUFSIZE)
    joinbuf_flush(jbuf);

  /* add channel to list of channels to send and update counts */
  jbuf->jb_channels[jbuf->jb_count++] = chan;
  jbuf->jb_strlen += len;

  /* if we've used up all slots, flush */
  if (jbuf->jb_count >= MAXJOINARGS)
    joinbuf_flush(jbuf);
}

/*
 * Flush the channel list to remote servers
 */
int
joinbuf_flush(struct JoinBuf *jbuf)
{
  char chanlist[BUFSIZE];
  int chanlist_i = 0;
  int i;

  if (!jbuf->jb_count || jbuf->jb_type == JOINBUF_TYPE_PARTALL ||
      jbuf->jb_type == JOINBUF_TYPE_JOIN)
    return 0; /* no joins to process */

  for (i = 0; i < jbuf->jb_count; i++) { /* build channel list */
    build_string(chanlist, &chanlist_i,
                 jbuf->jb_channels[i] ? jbuf->jb_channels[i]->chname : "0", 0,
                 i == 0 ? '\0' : ',');
    if (JOINBUF_TYPE_PART == jbuf->jb_type)
      /* Remove user from channel */
      remove_user_from_channel(jbuf->jb_source, jbuf->jb_channels[i]);

    jbuf->jb_channels[i] = 0; /* mark slot empty */
  }

  jbuf->jb_count = 0; /* reset base counters */
  jbuf->jb_strlen = ((jbuf->jb_type == JOINBUF_TYPE_PART ?
                      STARTJOINLEN : STARTCREATELEN) +
                     (jbuf->jb_comment ? strlen(jbuf->jb_comment) + 2 : 0));

  /* and send the appropriate command */
  switch (jbuf->jb_type) {
  case JOINBUF_TYPE_CREATE:
    sendcmdto_serv_butone(jbuf->jb_source, CMD_CREATE, jbuf->jb_connect,
                          "%s %Tu", chanlist, jbuf->jb_create);
    break;

  case JOINBUF_TYPE_PART:
    sendcmdto_serv_butone(jbuf->jb_source, CMD_PART, jbuf->jb_connect,
                          jbuf->jb_comment ? "%s :%s" : "%s", chanlist,
                          jbuf->jb_comment);
    break;
  }

  return 0;
}

/* Returns TRUE (1) if client is invited, FALSE (0) if not */
int IsInvited(struct Client* cptr, const void* chptr)
{
  struct SLink *lp;

  for (lp = (cli_user(cptr))->invited; lp; lp = lp->next)
    if (lp->value.chptr == chptr)
      return 1;
  return 0;
}

/* RevealDelayedJoin: sends a join for a hidden user */

void RevealDelayedJoin(struct Membership *member) {
  ClearDelayedJoin(member);
  sendcmdto_channel_butserv_butone(member->user, CMD_JOIN, member->channel, member->user, 0, ":%H",
                                   member->channel);
  CheckDelayedJoins(member->channel);
}

/* CheckDelayedJoins: checks and clear +d if necessary */

void CheckDelayedJoins(struct Channel *chan) {
  struct Membership *memb2;
  
  if (chan->mode.mode & MODE_WASDELJOINS) {
    for (memb2=chan->members;memb2;memb2=memb2->next_member)
      if (IsDelayedJoin(memb2))
        break;
    
    if (!memb2) {
      /* clear +d */
      chan->mode.mode &= ~MODE_WASDELJOINS;
      sendcmdto_channel_butserv_butone(&me, CMD_MODE, chan, NULL, 0,
                                       "%H -d", chan);
    }
  }
}