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/*
* mod_example.c
* Example module for bscan.
*/
#include <bscan/bscan.h>
#include <bscan/module.h>
#include <stdio.h>
#ifndef MOD_NAME
#define MOD_NAME "mod_httpd"
#endif
#define HEADREQ "HEAD / HTTP/1.0\r\n\r\n"
static int isinit=0;
/*
* some variables from the binary-process
*/
extern int dlt_len;
extern u_char *align_buf;
extern unsigned short ip_options;
extern struct ip *ip;
extern struct Ether_header *eth;
extern u_int plen, pcaplen;
struct _mopt
{
unsigned short int dport; /* dport in NBO */
char *request; /* the http-request */
} static mopt;
/*
* static functions prototypes
*/
static int mdo_opt(int, char **, struct _opt *);
static void init_vars(struct _opt *);
static int process_rcv(struct _opt *);
/*
* print out usage informations
*/
void
musage()
{
printf ("\n"MOD_NAME"\n");
printf (" -p <port>, default 80\n");
printf (" -r <request>, default 'HEAD / HTTP/1.0'\n");
}
/*
* return 0 on success, != 0 on failure
*/
int
init(char **modname, int argc, char *argv[], struct _opt *opt)
{
#ifdef DEBUG
printf("MODULE INIT\n");
#endif
if (isinit)
return(-1);
*modname = MOD_NAME;
isinit = 1;
init_vars(opt);
if (mdo_opt(argc, argv, opt) != 0)
return(-1);
return(0);
}
/*
* fini-routine. called on cleanup
*/
int
fini()
{
#ifdef DEBUG
printf("MODULE FINI\n");
#endif
return(0);
}
/*
*
*/
int
callmdl(int entry, struct _opt *opt)
{
#ifdef DEBUG
printf("MODULE CALLMDL\n");
#endif
if (entry == MOD_FIRSTPKG)
return(RMOD_SKIP);
if (entry == MOD_RCV)
process_rcv(opt);
return(RMOD_OK);
}
/*
***********************************************************
* Our OWN/static functions for THIS module *
***********************************************************
*/
/*
* initialize all local variables.
* We use some 'unused' variables of the masterprogramm
*/
static void
init_vars(struct _opt *opt)
{
mopt.dport = htons(80);
mopt.request = HEADREQ;
}
/*
* LOCAL/STATIC function, only available in the module
* return 0 on success, != 0 on failure
*/
static int
mdo_opt(int argc, char *argv[], struct _opt *opt)
{
extern char *optarg;
/*extern int optind, opterr, optopt;*/
int c;
while ((c = getopt (argc, argv, "p:r:")) != -1)
{
switch (c)
{
case 'p':
mopt.dport = htons(strtoul (optarg, (char **) NULL, 10));
break;
case 'r':
mopt.request = optarg;
fprintf(stderr, MOD_NAME ": requesting \"%s\"\n", optarg);
break;
case ':':
fprintf(stderr, "missing parameter\n");
return(-1);
default:
return(-1);
}
}
return(0);
}
/*
* process incoming packets
* IP-packet is verified and variables valid (ip_options, *ip)
*/
static int
process_rcv(struct _opt *opt)
{
struct tcphdr *tcp;
unsigned short tcp_options = 0;
uint iphdr_len = 0;
if (ip->ip_p != IPPROTO_TCP)
return(0);
iphdr_len = sizeof(*ip) + ip_options;
tcp = (struct tcphdr *) (align_buf + iphdr_len);
if (vrfy_tcp(tcp, plen - dlt_len - iphdr_len, &tcp_options) != 0)
return(0);
if (tcp->th_sport != mopt.dport)
return(0);
if ((tcp->th_flags & (TH_SYN | TH_ACK)) == (TH_SYN | TH_ACK))
answer_tcp (opt->sox, ip, tcp, TH_ACK | TH_PUSH, mopt.request, strlen(mopt.request));
return(0);
}
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