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/*
* IP_MASQ_FTP CUSeeMe masquerading module
*
*
* Version: @(#)$Id: ip_masq_cuseeme.c,v 1.2 1997/11/28 15:32:18 alan 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
* Steven Clarke : Small changes for 2.1
*
*
*
* 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 <linux/init.h>
#include <net/protocol.h>
#include <net/udp.h>
/* #define IP_MASQ_NDEBUG */
#include <net/ip_masq.h>
#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()
/*
* 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];
/*
* Debug level
*/
static int debug=0;
MODULE_PARM(ports, "1-" __MODULE_STRING(MAX_MASQ_APP_PORTS) "i");
MODULE_PARM(debug, "i");
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, __u32 maddr)
{
struct sk_buff *skb = *skb_p;
struct iphdr *iph = skb->nh.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) maddr;
if(ntohs(cu_head->data_type) == 257)
IP_MASQ_DEBUG(1-debug, "Sending talk packet!\n");
}
return 0;
}
int
masq_cuseeme_in (struct ip_masq_app *mapp, struct ip_masq *ms, struct sk_buff **skb_p, __u32 maddr)
{
struct sk_buff *skb = *skb_p;
struct iphdr *iph = skb->nh.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) maddr)
{
/* 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
*/
__initfunc(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
IP_MASQ_DEBUG(1-debug, "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;
IP_MASQ_DEBUG(1-debug, "CuSeeMe: unloaded support on port[%d] = %d\n", i, ports[i]);
}
}
}
return k;
}
#ifdef MODULE
EXPORT_NO_SYMBOLS;
int init_module(void)
{
if (ip_masq_cuseeme_init() != 0)
return -EIO;
return 0;
}
void cleanup_module(void)
{
if (ip_masq_cuseeme_done() != 0)
IP_MASQ_DEBUG(1-debug, "ip_masq_cuseeme: can't remove module");
}
#endif /* MODULE */
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