Linux Packet dropper -

Hi

I m trying a packet dropper program(KERNEL MODULE) in Linux 2.4 (I got
this from a site),

I m getting some unusal erros in the Linux Header files itself.

please help me in solving the erros.

The code goes like this:



/* packet_dropper.c
*
* This program provides an example of how to install a module into a
* slightly modified kernel that will randomly drop packets for a
specific
* (hard-coded) host.
* See linux/drivers/char/random.c for details of get_random_bytes().
* Usage (must be root to use):
* /sbin/insmod packet_dropper
* /sbin/rmmod packet_dropper
*/

#define MODULE
#define MAX_UNSIGNED_SHORT 65535

#include <linux/module.h>
#include <linux/skbuff.h> /* for struct sk_buff */
#include <linux/ip.h> /* for struct iphdr */

extern int (*test_function)(struct sk_buff *); /* calling
function */
extern void get_random_bytes(void *buf, int nbytes); /* random function
*/
unsigned short cutoff; /* drop cutoff */
float rate = 0.050; /* drop percentage
*/
__u32 target = 0x220010AC; /* 172.16.0.34 */

/************************************************************
packet_dropper
* this is what dev_queue_xmit will call while this module is installed
*/
int packet_dropper(struct sk_buff *skb) {
unsigned short t;
if (skb->nh.iph->daddr == target) {
get_random_bytes(&t,2);
if (t <= cutoff) return 1; /* drop this packet */
}
return 0; /* continue with normal routine */
} /* packet_dropper */

/***************************************************************
init_module
* this function replaces the null pointer with a real one */
int init_module() {
EXPORT_NO_SYMBOLS;
cutoff = rate * MAX_UNSIGNED_SHORT;
test_function = packet_dropper;
printk("<1> packet_dropper: now dropping packets\n");
return 0;
} /* init_module */

/************************************************************
cleanup_module
* this function resets the function pointer back to null */
void cleanup_module() {
test_function = 0;
printk("<1> packet_dropper: uninstalled\n");
} /* cleanup_module */




i m compiling it like this
gcc -D __KERNEL__ -D MODULE -O2 -Wall -Isystem/lib/modules/'uname
-r'/build/include -o packet_dropper.o -c packet_dropper.c
(there is no problem with the flags ..i checked it with a sample module
...its working fine)


STRANGE ERROS THAT I GOT:

[ROOT@LOCALHOST] #gcc -D __KERNEL__ -D MODULE -O2 -Wall
-Isystem/lib/modules/'uname -r'/build/include -o packet_dropper.o -c
packet_dropper.c
packet_dropper.c:14:1: warning: "MODULE" redefined
packet_dropper.c:1:1: warning: this is the location of the previous
definition
In file included from /usr/include/linux/fs.h:23,
from /usr/include/linux/capability.h:17,
from /usr/include/linux/binfmts.h:5,
from /usr/include/linux/sched.h:9,
from /usr/include/linux/skbuff.h:19,
from packet_dropper.c:18:
/usr/include/linux/string.h:8:2: warning: #warning Using kernel header
in userland!
In file included from /usr/include/linux/sched.h:14,
from /usr/include/linux/skbuff.h:19,
from packet_dropper.c:18:
/usr/include/linux/timex.h:173: field `time' has incomplete type
In file included from /usr/include/linux/bitops.h:69,
from /usr/include/asm/system.h:7,
from /usr/include/linux/sched.h:16,
from /usr/include/linux/skbuff.h:19,
from packet_dropper.c:18:
/usr/include/asm/bitops.h:327:2: warning: #warning This includefile is
not available on all architectures.
/usr/include/asm/bitops.h:328:2: warning: #warning Using kernel headers
in userspace: atomicity not guaranteed
In file included from /usr/include/linux/signal.h:4,
from /usr/include/linux/sched.h:25,
from /usr/include/linux/skbuff.h:19,
from packet_dropper.c:18:
/usr/include/asm/signal.h:107: parse error before "sigset_t"
/usr/include/asm/signal.h:110: parse error before '}' token
In file included from /usr/include/linux/sched.h:81,
from /usr/include/linux/skbuff.h:19,
from packet_dropper.c:18:
/usr/include/linux/timer.h:45: parse error before "spinlock_t"
/usr/include/linux/timer.h:53: parse error before '}' token
/usr/include/linux/timer.h:67: parse error before "tvec_base_t"
/usr/include/linux/timer.h:101: parse error before "tvec_bases"
/usr/include/linux/timer.h: In function `init_timer':
/usr/include/linux/timer.h:105: dereferencing pointer to incomplete
type
/usr/include/linux/timer.h:105: dereferencing pointer to incomplete
type
/usr/include/linux/timer.h:106: dereferencing pointer to incomplete
type
/usr/include/linux/timer.h: In function `timer_pending':
/usr/include/linux/timer.h:121: dereferencing pointer to incomplete
type
In file included from /usr/include/linux/highmem.h:5,
from /usr/include/linux/skbuff.h:26,
from packet_dropper.c:18:
/usr/include/asm/pgalloc.h:6:24: asm/fixmap.h: No such file or
directory
In file included from /usr/include/linux/highmem.h:5,
from /usr/include/linux/skbuff.h:26,
from packet_dropper.c:18:
/usr/include/asm/pgalloc.h: At top level:
/usr/include/asm/pgalloc.h:57: parse error before '*' token
/usr/include/asm/pgalloc.h: In function `get_pgd_slow':
/usr/include/asm/pgalloc.h:59: `pgd_t' undeclared (first use in this
function)
/usr/include/asm/pgalloc.h:59: (Each undeclared identifier is reported
only once
/usr/include/asm/pgalloc.h:59: for each function it appears in.)
/usr/include/asm/pgalloc.h:59: `pgd' undeclared (first use in this
function)
/usr/include/asm/pgalloc.h:59: parse error before ')' token
/usr/include/asm/pgalloc.h:62: `USER_PTRS_PER_PGD' undeclared (first
use in this function)
/usr/include/asm/pgalloc.h:63: `swapper_pg_dir' undeclared (first use
in this function)
/usr/include/asm/pgalloc.h:63: `PTRS_PER_PGD' undeclared (first use in
this function)
/usr/include/asm/pgalloc.h: At top level:
/usr/include/asm/pgalloc.h:70: parse error before '*' token
/usr/include/asm/pgalloc.h: In function `get_pgd_fast':
/usr/include/asm/pgalloc.h:80: `pgd_t' undeclared (first use in this
function)
/usr/include/asm/pgalloc.h:80: parse error before ')' token
/usr/include/asm/pgalloc.h: At top level:
/usr/include/asm/pgalloc.h:83: parse error before '*' token
/usr/include/asm/pgalloc.h: In function `free_pgd_fast':
/usr/include/asm/pgalloc.h:85: `pgd' undeclared (first use in this
function)
/usr/include/asm/pgalloc.h: At top level:
/usr/include/asm/pgalloc.h:90: parse error before '*' token
/usr/include/asm/pgalloc.h: In function `free_pgd_slow':
/usr/include/asm/pgalloc.h:99: `pgd' undeclared (first use in this
function)
/usr/include/asm/pgalloc.h: At top level:
/usr/include/asm/pgalloc.h:103: parse error before '*' token
/usr/include/asm/pgalloc.h: In function `pte_alloc_one':
/usr/include/asm/pgalloc.h:105: `pte_t' undeclared (first use in this
function)
/usr/include/asm/pgalloc.h:105: `pte' undeclared (first use in this
function)
/usr/include/asm/pgalloc.h:109: parse error before ')' token
/usr/include/asm/pgalloc.h: At top level:
/usr/include/asm/pgalloc.h:118: parse error before '*' token
/usr/include/asm/pgalloc.h: In function `pte_alloc_one_fast':
/usr/include/asm/pgalloc.h:127: `pte_t' undeclared (first use in this
function)
/usr/include/asm/pgalloc.h:127: parse error before ')' token
/usr/include/asm/pgalloc.h: At top level:
/usr/include/asm/pgalloc.h:130: parse error before '*' token
/usr/include/asm/pgalloc.h: In function `pte_free_fast':
/usr/include/asm/pgalloc.h:132: `pte' undeclared (first use in this
function)
/usr/include/asm/pgalloc.h: At top level:
/usr/include/asm/pgalloc.h:137: parse error before '*' token
/usr/include/asm/pgalloc.h: In function `pte_free_slow':
/usr/include/asm/pgalloc.h:139: `pte' undeclared (first use in this
function)
/usr/include/asm/pgalloc.h: In function `flush_tlb_mm':
/usr/include/asm/pgalloc.h:183: `current' undeclared (first use in this
function)
/usr/include/asm/pgalloc.h: In function `flush_tlb_page':
/usr/include/asm/pgalloc.h:190: dereferencing pointer to incomplete
type
/usr/include/asm/pgalloc.h:190: `current' undeclared (first use in this
function)
/usr/include/asm/pgalloc.h: In function `flush_tlb_range':
/usr/include/asm/pgalloc.h:197: `current' undeclared (first use in this
function)
In file included from packet_dropper.c:18:
/usr/include/linux/skbuff.h: At top level:
/usr/include/linux/skbuff.h:100: parse error before "spinlock_t"
/usr/include/linux/skbuff.h:120: parse error before "atomic_t"
/usr/include/linux/skbuff.h:124: parse error before '}' token
/usr/include/linux/skbuff.h:183: parse error before "atomic_t"
/usr/include/linux/skbuff.h:215: parse error before '}' token
packet_dropper.c: In function `packet_dropper':
packet_dropper.c:31: dereferencing pointer to incomplete type
packet_dropper.c: In function `init_module':
packet_dropper.c:44: warning: implicit declaration of function `printk'

I have given all the relevant info.
if you need any other info. do infom me.

Any help is appreciated.

Thanks,
SaranJothy.
Saranjothy (at) gmail (dot) com

.

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