/*
* IP_MASQ_IRC irc masquerading module
*
*
* Version: @(#)ip_masq_irc.c 0.01 03/20/96
*
* Author: Juan Jose Ciarlante
*
*
* Fixes:
* - set NO_DADDR flag in ip_masq_new().
* - Added multiple port support (Nigel Metheringham)
*
* FIXME:
* - detect also previous "PRIVMSG" string ?.
*
* 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 <linux/types.h>
#include <linux/kernel.h>
#include <asm/system.h>
#include <linux/skbuff.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <net/protocol.h>
#include <net/tcp.h>
#include <net/ip_masq.h>
#ifndef DEBUG_CONFIG_IP_MASQ_IRC
#define DEBUG_CONFIG_IP_MASQ_IRC 0
#endif
/*
* List of ports (up to MAX_MASQ_APP_PORTS) to be handled by helper
* First port is set to the default port.
*/
int ports[MAX_MASQ_APP_PORTS] = {6667}; /* I rely on the trailing items being set to zero */
struct ip_masq_app *masq_incarnations[MAX_MASQ_APP_PORTS];
static int
masq_irc_init_1 (struct ip_masq_app *mapp, struct ip_masq *ms)
{
MOD_INC_USE_COUNT;
return 0;
}
static int
masq_irc_done_1 (struct ip_masq_app *mapp, struct ip_masq *ms)
{
MOD_DEC_USE_COUNT;
return 0;
}
int
masq_irc_out (struct ip_masq_app *mapp, struct ip_masq *ms, struct sk_buff **skb_p, struct device *dev)
{
struct sk_buff *skb;
struct iphdr *iph;
struct tcphdr *th;
char *data, *data_limit;
__u32 s_addr;
__u16 s_port;
struct ip_masq *n_ms;
char buf[20]; /* "m_addr m_port" (dec base)*/
unsigned buf_len;
int diff;
int xtra_args = 0; /* extra int args wanted after addr */
char *dcc_p, *addr_beg_p, *addr_end_p;
skb = *skb_p;
iph = skb->h.iph;
th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]);
data = (char *)&th[1];
/*
* Hunt irc DCC string, the _shortest_:
*
* strlen("DCC CHAT chat AAAAAAAA P\x01\n")=26
* strlen("DCC SEND F AAAAAAAA P S\x01\n")=25
* AAAAAAAAA: bound addr (1.0.0.0==16777216, min 8 digits)
* P: bound port (min 1 d )
* F: filename (min 1 d )
* S: size (min 1 d )
* 0x01, \n: terminators
*/
data_limit = skb->h.raw + skb->len;
while (data < (data_limit - 25) )
{
if (memcmp(data,"DCC ",4)) {
data ++;
continue;
}
dcc_p = data;
data += 4; /* point to DCC cmd */
if (memcmp(data, "CHAT ", 5) == 0 ||
memcmp(data, "SEND ", 5) == 0)
{
/*
* extra arg (file_size) req. for "SEND"
*/
if (*data == 'S') xtra_args++;
data += 5;
}
else
continue;
/*
* skip next string.
*/
while( *data++ != ' ')
/*
* must still parse, at least, "AAAAAAAA P\x01\n",
* 12 bytes left.
*/
if (data > (data_limit-12)) return 0;
addr_beg_p = data;
/*
* client bound address in dec base
*/
s_addr = simple_strtoul(data,&data,10);
if (*data++ !=' ')
continue;
/*
* client bound port in dec base
*/
s_port = simple_strtoul(data,&data,10);
addr_end_p = data;
/*
* should check args consistency?
*/
while(xtra_args) {
if (*data != ' ')
break;
data++;
simple_strtoul(data,&data,10);
xtra_args--;
}
if (xtra_args != 0) continue;
/*
* terminators.
*/
if (data[0] != 0x01)
continue;
if (data[1]!='\r' && data[1]!='\n')
continue;
/*
* Now create an masquerade entry for it
* must set NO_DPORT and NO_DADDR because
* connection is requested by another client.
*/
n_ms = ip_masq_new(dev, IPPROTO_TCP,
htonl(s_addr),htons(s_port),
0, 0,
IP_MASQ_F_NO_DPORT|IP_MASQ_F_NO_DADDR
);
if (n_ms==NULL)
return 0;
ip_masq_set_expire(n_ms, ip_masq_expire->tcp_fin_timeout);
/*
* Replace the old "address port" with the new one
*/
buf_len = sprintf(buf,"%lu %u",
ntohl(n_ms->maddr),ntohs(n_ms->mport));
/*
* Calculate required delta-offset to keep TCP happy
*/
diff = buf_len - (addr_end_p-addr_beg_p);
#if DEBUG_CONFIG_IP_MASQ_IRC
*addr_beg_p = '\0';
printk("masq_irc_out(): '%s' %X:%X detected (diff=%d)\n", dcc_p, s_addr,s_port, diff);
#endif
/*
* No shift.
*/
if (diff==0)
{
/*
* simple case, just copy.
*/
memcpy(addr_beg_p,buf,buf_len);
return 0;
}
*skb_p = ip_masq_skb_replace(skb, GFP_ATOMIC,
addr_beg_p, addr_end_p-addr_beg_p,
buf, buf_len);
return diff;
}
return 0;
}
/*
* Main irc object
* You need 1 object per port in case you need
* to offer also other used irc ports (6665,6666,etc),
* they will share methods but they need own space for
* data.
*/
struct ip_masq_app ip_masq_irc = {
NULL, /* next */
"irc", /* name */
0, /* type */
0, /* n_attach */
masq_irc_init_1, /* init_1 */
masq_irc_done_1, /* done_1 */
masq_irc_out, /* pkt_out */
NULL /* pkt_in */
};
/*
* ip_masq_irc initialization
*/
int ip_masq_irc_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_irc, sizeof(struct ip_masq_app));
if ((j = register_ip_masq_app(masq_incarnations[i],
IPPROTO_TCP,
ports[i]))) {
return j;
}
#if DEBUG_CONFIG_IP_MASQ_IRC
printk("Irc: 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_irc fin.
*/
int ip_masq_irc_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_IRC
printk("Irc: unloaded support on port[%d] = %d\n",
i, ports[i]);
#endif
}
}
}
return k;
}
#ifdef MODULE
int init_module(void)
{
if (ip_masq_irc_init() != 0)
return -EIO;
register_symtab(NULL);
return 0;
}
void cleanup_module(void)
{
if (ip_masq_irc_done() != 0)
printk("ip_masq_irc: can't remove module");
}
#endif /* MODULE */
