/*
 * Copyright (c) 2005 William Pitcock <nenolod -at- nenolod.net>
 * and Jilles Tjoelker <jilles -at- stack.nl>
 * All rights reserved.
 *
 * Redistribution in both source and binary forms are permitted
 * provided that the above copyright notice remains unchanged.
 *
 * m_chghost.c: A module for handling spoofing dynamically.
 */

#include "stdinc.h"
#include "send.h"
#include "channel.h"
#include "client.h"
#include "common.h"
#include "config.h"
#include "ircd.h"
#include "numeric.h"
#include "s_conf.h"
#include "s_newconf.h"
#include "s_serv.h"
#include "s_user.h"
#include "hash.h"
#include "msg.h"
#include "parse.h"
#include "modules.h"
#include "whowas.h"
#include "monitor.h"

static int me_realhost(struct Client *, struct Client *, int, const char **);
static int ms_chghost(struct Client *, struct Client *, int, const char **);
static int me_chghost(struct Client *, struct Client *, int, const char **);
static int mo_chghost(struct Client *, struct Client *, int, const char **);

struct Message realhost_msgtab = {
    "REALHOST", 0, 0, 0, MFLG_SLOW,
    {mg_ignore, mg_ignore, mg_ignore, mg_ignore, {me_realhost, 2}, mg_ignore}
};

struct Message chghost_msgtab = {
    "CHGHOST", 0, 0, 0, MFLG_SLOW,
    {mg_ignore, mg_not_oper, {ms_chghost, 3}, {ms_chghost, 3}, {me_chghost, 3}, {mo_chghost, 3}}
};

mapi_clist_av1 chghost_clist[] = { &chghost_msgtab, &realhost_msgtab, NULL };

DECLARE_MODULE_AV1(chghost, NULL, NULL, chghost_clist, NULL, NULL, "$Revision: 3424 $");

/* clean_host()
 *
 * input	- host to check
 * output	- 0 if erroneous, else 0
 * side effects -
 */
static int
clean_host(const char *host)
{
    int len = 0;
    const char *last_slash = 0;

    if (*host == '\0' || *host == ':')
        return 0;

    for(; *host; host++) {
        len++;

        if(!IsHostChar(*host))
            return 0;
        if(*host == '/')
            last_slash = host;
    }

    if(len > HOSTLEN)
        return 0;

    if(last_slash && IsDigit(last_slash[1]))
        return 0;

    return 1;
}

/*
 * me_realhost
 * parv[1] = real host
 *
 * Yes this contains a little race condition if someone does a whois
 * in between the UID and REALHOST and use_whois_actually is enabled.
 * I don't think that's a big problem as the whole thing is a
 * race condition.
 */
static int
me_realhost(struct Client *client_p, struct Client *source_p,
            int parc, const char *parv[])
{
    if (!IsPerson(source_p))
        return 0;

    del_from_hostname_hash(source_p->orighost, source_p);
    rb_strlcpy(source_p->orighost, parv[1], sizeof source_p->orighost);
    if (irccmp(source_p->host, source_p->orighost))
        SetDynSpoof(source_p);
    else
        ClearDynSpoof(source_p);
    add_to_hostname_hash(source_p->orighost, source_p);
    return 0;
}

static int
do_chghost(struct Client *source_p, struct Client *target_p,
           const char *newhost, int is_encap)
{
    if (!clean_host(newhost)) {
        sendto_realops_snomask(SNO_GENERAL, is_encap ? L_ALL : L_NETWIDE, "%s attempted to change hostname for %s to %s (invalid)",
                               IsServer(source_p) ? source_p->name : get_oper_name(source_p),
                               target_p->name, newhost);
        /* sending this remotely may disclose important
         * routing information -- jilles */
        if (is_encap ? MyClient(target_p) : !ConfigServerHide.flatten_links)
            sendto_one_notice(target_p, ":*** Notice -- %s attempted to change your hostname to %s (invalid)",
                              source_p->name, newhost);
        return 0;
    }
    change_nick_user_host(target_p, target_p->name, target_p->username, newhost, 0, "Changing host");
    if (irccmp(target_p->host, target_p->orighost)) {
        SetDynSpoof(target_p);
        if (MyClient(target_p))
            sendto_one_numeric(target_p, RPL_HOSTHIDDEN, "%s :is now your hidden host (set by %s)", target_p->host, source_p->name);
    } else {
        ClearDynSpoof(target_p);
        if (MyClient(target_p))
            sendto_one_numeric(target_p, RPL_HOSTHIDDEN, "%s :hostname reset by %s", target_p->host, source_p->name);
    }
    if (MyClient(source_p))
        sendto_one_notice(source_p, ":Changed hostname for %s to %s", target_p->name, target_p->host);
    if (!IsServer(source_p) && !IsService(source_p))
        sendto_realops_snomask(SNO_GENERAL, L_ALL, "%s changed hostname for %s to %s", get_oper_name(source_p), target_p->name, target_p->host);
    return 1;
}

/*
 * ms_chghost
 * parv[1] = target
 * parv[2] = host
 */
static int
ms_chghost(struct Client *client_p, struct Client *source_p,
           int parc, const char *parv[])
{
    struct Client *target_p;

    if (!(target_p = find_person(parv[1])))
        return -1;

    if (do_chghost(source_p, target_p, parv[2], 0)) {
        sendto_server(client_p, NULL,
                      CAP_EUID | CAP_TS6, NOCAPS, ":%s CHGHOST %s %s",
                      use_id(source_p), use_id(target_p), parv[2]);
        sendto_server(client_p, NULL,
                      CAP_TS6, CAP_EUID, ":%s ENCAP * CHGHOST %s :%s",
                      use_id(source_p), use_id(target_p), parv[2]);
    }

    return 0;
}

/*
 * me_chghost
 * parv[1] = target
 * parv[2] = host
 */
static int
me_chghost(struct Client *client_p, struct Client *source_p,
           int parc, const char *parv[])
{
    struct Client *target_p;

    if (!(target_p = find_person(parv[1])))
        return -1;

    do_chghost(source_p, target_p, parv[2], 1);

    return 0;
}

/*
 * mo_chghost
 * parv[1] = target
 * parv[2] = host
 */
/* Disable this because of the abuse potential -- jilles
 * No, make it toggleable via ./configure. --nenolod
 */
static int
mo_chghost(struct Client *client_p, struct Client *source_p,
           int parc, const char *parv[])
{
#ifdef ENABLE_OPER_CHGHOST
    struct Client *target_p;

    if(!IsOperAdmin(source_p)) {
        sendto_one(source_p, form_str(ERR_NOPRIVS),
                   me.name, source_p->name, "admin");
        return 0;
    }

    if (!(target_p = find_named_person(parv[1]))) {
        sendto_one_numeric(source_p, ERR_NOSUCHNICK,
                           form_str(ERR_NOSUCHNICK), parv[1]);
        return 0;
    }

    if (!clean_host(parv[2])) {
        sendto_one_notice(source_p, ":Hostname %s is invalid", parv[2]);
        return 0;
    }

    do_chghost(source_p, target_p, parv[2], 0);

    sendto_server(NULL, NULL,
                  CAP_EUID | CAP_TS6, NOCAPS, ":%s CHGHOST %s %s",
                  use_id(source_p), use_id(target_p), parv[2]);
    sendto_server(NULL, NULL,
                  CAP_TS6, CAP_EUID, ":%s ENCAP * CHGHOST %s :%s",
                  use_id(source_p), use_id(target_p), parv[2]);
#else
    sendto_one_numeric(source_p, ERR_DISABLED, form_str(ERR_DISABLED),
                       "CHGHOST");
#endif

    return 0;
}