/* 
 * Copyright (C) 2001,2004 Igor Sysoev, http://sysoev.ru/en/
 *
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 /

/*
MODULE-DEFINITION-START
Name: realip_module
ConfigStart
ConfigEnd
MODULE-DEFINITION-END
*/

#include "httpd.h"
#include "http_config.h"


#define MOD_REALIP_VER   "mod_realip/2.0"


#define REALIP_ON    1
#define REALIP_OFF   2
#define REALIP_XFWD  4

typedef struct {
    int            realip;
    array_header  *hosts;
} server_conf;


module realip_module;


static void set_real_remote_ip(request_rec *r, server_conf *conf)
{
    int              i, found;
    char            *x_real_ip, *token, *last_ip;
    const char      *x_fwd_for;
    struct in_addr  *addr, raddr;

    if (conf->hosts->nelts) {
        found = 0;
        addr = (struct in_addr *) conf->hosts->elts;
        raddr = r->connection->remote_addr.sin_addr;

        for (i = 0; i < conf->hosts->nelts; i++) {
            if (addr[i].s_addr == raddr.s_addr) {
                found = 1;
                break;
            }
        }

        if (!found) {
            return;
        }
    }

    if (conf->realip & REALIP_XFWD) {
        if (x_fwd_for = ap_table_get(r->headers_in, "X-Forwarded-For")) {
            while (*x_fwd_for
                   && (token = ap_get_token(r->pool, &x_fwd_for, 0)))
            {
                /* ap_get_token() bug */
                if (*x_fwd_for == ',' || *x_fwd_for == ';')
                    x_fwd_for++;

                last_ip = token;
            }

            r->connection->remote_ip = last_ip;
        }

    } else {
        if (x_real_ip = (char *)ap_table_get(r->headers_in, "X-Real-IP")) {
            r->connection->remote_ip = x_real_ip;
        }
    }

    r->connection->remote_addr.sin_addr.s_addr =
                                        ap_inet_addr(r->connection->remote_ip);
}


static int realip_postread(request_rec *r)
{
    server_conf *conf;

    conf = (server_conf *)
             ap_get_module_config(r->server->module_config, &realip_module);

    if (conf->realip & REALIP_OFF) {
        return DECLINED;
    }

    if (conf->realip & REALIP_ON || conf->hosts->nelts) {
        set_real_remote_ip(r, conf);
    }

    return DECLINED;
}


static void *realip_config(pool *p, server_rec *s)
{
    server_conf     *conf;

    conf = ap_palloc(p, sizeof(server_conf));

    conf->realip = 0;
    conf->hosts = ap_make_array(p, 3, sizeof(struct in_addr));

    return (void *)conf;
}


static void *realip_merge(pool *p, void *base, void *new)
{
    server_conf *parent = (server_conf *) base;
    server_conf *child = (server_conf *) new;

    server_conf *merged;

    merged = ap_pcalloc(p, sizeof(server_conf));

    merged->realip = child->realip ? child->realip : parent->realip;
    merged->hosts = child->hosts->nelts ? child->hosts : parent->hosts;

    return (void *)merged;
}


static const char *set_realip(cmd_parms *cmd, void *dummy, char *host)
{
    struct hostent  *h;
    struct in_addr  *addr;
    server_conf     *conf;
    
    conf = (server_conf *)
             ap_get_module_config(cmd->server->module_config, &realip_module);

    if (strcmp(host, "on") == 0) {
        conf->realip |= REALIP_ON;
        return NULL;
    }

    if (strcmp(host, "off") == 0) {
        conf->realip |= REALIP_OFF;
        return NULL;
    }

    if (strcmp(host, "xfwd") == 0) {
        conf->realip |= REALIP_XFWD;
        return NULL;
    }

    addr = ap_push_array(conf->hosts);

    if ((addr->s_addr = ap_inet_addr(host)) == INADDR_NONE) {
        if ((h = ap_pgethostbyname(cmd->pool, host)) != NULL
             && h->h_addr_list[0] != NULL)
        {
            *addr = *(struct in_addr *)(h->h_addr_list[0]);

        } else {
            return ap_psprintf(cmd->pool, "Can not resolve host %s", host);
        }
    }

    return NULL;
}


static const command_rec realip_cmds[] =
{
    {"RealIP", set_realip, NULL, RSRC_CONF, ITERATE,
     "set hosts that can override a real remote ip"},

    {NULL}
};


module realip_module =
{
    STANDARD_MODULE_STUFF,
    NULL,                             /* module initializer */
    NULL,                             /* per-directory config creator */
    NULL,                             /* dir config merger */
    realip_config,                    /* server config creator */
    realip_merge,                     /* server config merger */
    realip_cmds,                      /* command table */
    NULL,                             /* [9] list of handlers */
    NULL,                             /* [2] filename-to-URI translation */
    NULL,                             /* [5] check/validate user_id */
    NULL,                             /* [6] check user_id is valid *here* */
    NULL,                             /* [4] check access by host address */
    NULL,                             /* [7] MIME type checker/setter */
    NULL,                             /* [8] fixups */
    NULL,                             /* [10] logger */
    NULL,                             /* [3] header parser */
    NULL,                             /* process initializer */
    NULL,                             /* process exit/cleanup */   
    realip_postread,                  /* [1] post read_request handling */
};