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/*

 *              IP_MASQ_FTP CUSeeMe masquerading module

 *

 *

 * Version:     @(#)$Id: ip_masq_cuseeme.c,v 1.1 2005-12-20 10:41:09 jcastillo Exp $

 *

 * Author:      Richard Lynch

 *

 *

 * Fixes:

 *      Richard Lynch           :       Updated patch to conform to new module

 *                                      specifications

 *      Nigel Metheringham      :       Multiple port support

 *      Michael Owings          :       Fixed broken init code

 *                                      Added code to update inbound

 *                                      packets with correct local addresses.

 *                                      Fixes audio and "chat" problems

 *                                      Thanx to the CU-SeeMe Consortium for

 *                                      technical docs

 *

 *

 *

 *      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

 *      2 of the License, or (at your option) any later version.

 *

 * Multiple Port Support

 *      The helper can be made to handle up to MAX_MASQ_APP_PORTS (normally 12)

 *      with the port numbers being defined at module load time.  The module

 *      uses the symbol "ports" to define a list of monitored ports, which can

 *      be specified on the insmod command line as

 *              ports=x1,x2,x3...

 *      where x[n] are integer port numbers.  This option can be put into

 *      /etc/conf.modules (or /etc/modules.conf depending on your config)

 *      where modload will pick it up should you use modload to load your

 *      modules.

 *

 */

#include <linux/module.h>

#include <asm/system.h>

#include <linux/types.h>

#include <linux/kernel.h>

#include <linux/skbuff.h>

#include <linux/in.h>

#include <linux/ip.h>

#include <net/protocol.h>

#include <net/udp.h>

#include <net/ip_masq.h>

#ifndef DEBUG_CONFIG_IP_MASQ_CUSEEME

#define DEBUG_CONFIG_IP_MASQ_CUSEEME 0

#endif

#pragma pack(1)

/* CU-SeeMe Data Header */

typedef struct {

        u_short         dest_family;

        u_short         dest_port;

        u_long          dest_addr;

        short           family;

        u_short         port;

        u_long          addr;

        u_long          seq;

        u_short         msg;

        u_short         data_type;

        u_short         packet_len;

} cu_header;

/* Open Continue Header */

typedef struct  {

        cu_header       cu_head;

        u_short         client_count; /* Number of client info structs */

        u_long          seq_no;

        char            user_name[20];

        char            stuff[4]; /* flags,  version stuff,  etc */

}oc_header;

/* client info structures */

typedef struct {

        u_long          address; /* Client address */

        char            stuff[8]; /* Flags, pruning bitfield,  packet counts etc */

} client_info;

#pragma pack()

#ifdef MODULE

#define STATIC

#else

#define STATIC  static

#endif

/*

 * List of ports (up to MAX_MASQ_APP_PORTS) to be handled by helper

 * First port is set to the default port.

 */

STATIC int ports[MAX_MASQ_APP_PORTS] = {7648}; /* I rely on the trailing items being set to zero */

struct ip_masq_app *masq_incarnations[MAX_MASQ_APP_PORTS];

static int

masq_cuseeme_init_1 (struct ip_masq_app *mapp, struct ip_masq *ms)

{

        MOD_INC_USE_COUNT;

        return 0;

}

static int

masq_cuseeme_done_1 (struct ip_masq_app *mapp, struct ip_masq *ms)

{

        MOD_DEC_USE_COUNT;

        return 0;

}

int

masq_cuseeme_out (struct ip_masq_app *mapp, struct ip_masq *ms, struct sk_buff **skb_p, struct device *dev)

{

        struct sk_buff *skb = *skb_p;

        struct iphdr *iph = skb->h.iph;

        struct udphdr *uh = (struct udphdr *)&(((char *)iph)[iph->ihl*4]);

        cu_header *cu_head;

        char *data=(char *)&uh[1];

        if (skb->len - ((unsigned char *) data - skb->h.raw) >= sizeof(cu_header))

        {

                cu_head         = (cu_header *) data;

                /* cu_head->port   = ms->mport; */

                if( cu_head->addr )

                cu_head->addr = (u_long) dev->pa_addr;

#if DEBUG_CONFIG_IP_MASQ_CUSEEME          

                if(ntohs(cu_head->data_type) == 257)

                   printk(KERN_INFO "Sending talk packet!\n");

#endif    

        }

        return 0;

}

int

masq_cuseeme_in (struct ip_masq_app *mapp, struct ip_masq *ms, struct sk_buff **skb_p, struct device *dev)

{

        struct sk_buff *skb = *skb_p;

        struct iphdr *iph = skb->h.iph;

        struct udphdr *uh = (struct udphdr *)&(((char *)iph)[iph->ihl*4]);

        cu_header *cu_head;

        oc_header       *oc;

        client_info     *ci;

        char *data=(char *)&uh[1];

        u_short len = skb->len - ((unsigned char *) data - skb->h.raw);

        int             i, off;

        if (len >= sizeof(cu_header))

        {

                cu_head         = (cu_header *) data;

                if(cu_head->dest_addr) /* Correct destination address */

                        cu_head->dest_addr = (u_long) ms->saddr;

                if(ntohs(cu_head->data_type)==101 && len > sizeof(oc_header))

                {

                        oc = (oc_header * ) data;

                        /* Spin (grovel) thru client_info structs till we find our own */

                        off=sizeof(oc_header);

                        for(i=0;

                            (i < oc->client_count && off+sizeof(client_info) <= len);

                            i++)

                        {

                                ci=(client_info *)(data+off);

                                if(ci->address==(u_long) dev->pa_addr)

                                {

                                        /* Update w/ our real ip address and exit */

                                        ci->address = (u_long) ms->saddr;

                                        break;

                                }

                                else

                                   off+=sizeof(client_info);

                        }

                }

        }

        return 0;

}

struct ip_masq_app ip_masq_cuseeme = {

        NULL,                   /* next */

        "cuseeme",

        0,                      /* type */

        0,                      /* n_attach */

        masq_cuseeme_init_1,    /* ip_masq_init_1 */

        masq_cuseeme_done_1,    /* ip_masq_done_1 */

        masq_cuseeme_out,       /* pkt_out */

        masq_cuseeme_in         /* pkt_in */

};

/*

 *      ip_masq_cuseeme initialization

 */

int ip_masq_cuseeme_init(void)

{

        int i, j;

        for (i=0; (i<MAX_MASQ_APP_PORTS); i++) {

                if (ports[i]) {

                        if ((masq_incarnations[i] = kmalloc(sizeof(struct ip_masq_app),

                                                            GFP_KERNEL)) == NULL)

                                return -ENOMEM;

                        memcpy(masq_incarnations[i], &ip_masq_cuseeme, sizeof(struct ip_masq_app));

                        if ((j = register_ip_masq_app(masq_incarnations[i],

                                                      IPPROTO_UDP,

                                                      ports[i]))) {

                                return j;

                        }

#if DEBUG_CONFIG_IP_MASQ_CUSEEME

                        printk(KERN_INFO "CuSeeMe: loaded support on port[%d] = %d\n",

                               i, ports[i]);

#endif

                } else {

                        /* To be safe, force the incarnation table entry to NULL */

                        masq_incarnations[i] = NULL;

                }

        }

        return 0;

}

/*

 *      ip_masq_cuseeme fin.

 */

int ip_masq_cuseeme_done(void)

{

        int i, j, k;

        k=0;

        for (i=0; (i<MAX_MASQ_APP_PORTS); i++) {

                if (masq_incarnations[i]) {

                        if ((j = unregister_ip_masq_app(masq_incarnations[i]))) {

                                k = j;

                        } else {

                                kfree(masq_incarnations[i]);

                                masq_incarnations[i] = NULL;

#if DEBUG_CONFIG_IP_MASQ_CUSEEME

                                printk(KERN_INFO "CuSeeMe: unloaded support on port[%d] = %d\n",

                                       i, ports[i]);

#endif

                        }

                }

        }

        return k;

}

#ifdef MODULE

int init_module(void)

{

        if (ip_masq_cuseeme_init() != 0)

                return -EIO;

        register_symtab(0);

        return 0;

}

void cleanup_module(void)

{

        if (ip_masq_cuseeme_done() != 0)

                printk(KERN_INFO "ip_masq_cuseeme: can't remove module");

}

#endif /* MODULE */