ip.c

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/*
 * ip.c
 *
 * Copyright (c) 2001 Dug Song <dugsong@monkey.org>
 *
 * $Id: ip.c,v 1.10 2002/02/08 07:43:53 dugsong Exp $
 */

#include "config.h"

#include <sys/types.h>

#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include "dnet.h"
#include "aton.h"
#include "mod.h"

void
ip_usage(void)
{
        fprintf(stderr, "Usage: dnet ip [tos|id|off|ttl|proto|src|dst "
            "<value>] ... \n");
        exit(1);
}

int
ip_main(int argc, char *argv[])
{
        struct ip_hdr *ip;
        struct addr addr;
        u_char *p, buf[IP_LEN_MAX];     /* XXX */
        char *name, *value;
        int c, len;
        
        srand(time(NULL));

        ip = (struct ip_hdr *)buf;
        ip->ip_hl = 5;
        ip->ip_v = 4;
        ip->ip_tos = 0;
        ip->ip_id = rand() & 0xffff;
        ip->ip_off = 0;
        ip->ip_ttl = IP_TTL_MAX;
        ip->ip_p = rand() & 0xff;
        ip->ip_sum = 0;
        ip->ip_src = rand();
        ip->ip_dst = rand();

        for (c = 1; c + 1 < argc; c += 2) {
                name = argv[c];
                value = argv[c + 1];
                
                if (strcmp(name, "tos") == 0)
                        ip->ip_tos = atoi(value);
                else if (strcmp(name, "id") == 0)
                        ip->ip_id = ntohs(atoi(value));
                else if (strcmp(name, "off") == 0) {
                        if (off_aton(value, &ip->ip_off) < 0)
                                ip_usage();
                } else if (strcmp(name, "ttl") == 0)
                        ip->ip_ttl = atoi(value);
                else if (strcmp(name, "proto") == 0) {
                        if (proto_aton(value, &ip->ip_p) < 0)
                                ip_usage();
                } else if (strcmp(name, "src") == 0) {
                        if (addr_aton(value, &addr) < 0)
                                ip_usage();
                        ip->ip_src = addr.addr_ip;
                } else if (strcmp(name, "dst") == 0) {
                        if (addr_aton(value, &addr) < 0)
                                ip_usage();
                        ip->ip_dst = addr.addr_ip;
                } else
                        ip_usage();
        }
        argc -= c;
        argv += c;
        
        if (argc != 0)
                ip_usage();
        
        if (isatty(STDIN_FILENO))
                errx(1, "can't read IP payload from tty");
        
        p = buf + IP_HDR_LEN;
        len = sizeof(buf) - (p - buf);
        
        while ((c = read(STDIN_FILENO, p, len)) > 0) {
                p += c;
                len -= c;
        }
        len = p - buf;
        
        ip->ip_len = htons(len);
        
        ip_checksum(buf, len);
        
        if (write(STDOUT_FILENO, buf, len) != len)
                err(1, "write");

        return (0);
}

struct mod mod_ip = {
        "ip",
        MOD_TYPE_ENCAP,
        ip_main
};

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