tcp.c

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/*
 * tcp.c
 *
 * Copyright (c) 2001 Dug Song <dugsong@monkey.org>
 *
 * $Id: tcp.c,v 1.8 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
tcp_usage(void)
{
        fprintf(stderr, "Usage: dnet tcp [sport|dport|flags|seq|ack|"
            "win|urp <value>] ...\n");
        exit(1);
}

int
tcp_main(int argc, char *argv[])
{
        struct tcp_hdr *tcp;
        u_char *p, buf[IP_LEN_MAX];     /* XXX */
        char *name, *value;
        int c, len;
        
        srand(time(NULL));
        
        tcp = (struct tcp_hdr *)buf;
        
        memset(tcp, 0, sizeof(*tcp));
        tcp->th_sport = rand() & 0xffff;
        tcp->th_dport = rand() & 0xffff;
        tcp->th_seq = rand();
        tcp->th_ack = 0;
        tcp->th_off = 5;
        tcp->th_flags = TH_SYN;
        tcp->th_win = TCP_WIN_MAX;
        tcp->th_urp = 0;

        for (c = 1; c + 1 < argc; c += 2) {
                name = argv[c];
                value = argv[c + 1];
                
                if (strcmp(name, "sport") == 0) {
                        if (port_aton(value, &tcp->th_sport) < 0)
                                tcp_usage();
                } else if (strcmp(name, "dport") == 0) {
                        if (port_aton(value, &tcp->th_dport) < 0)
                                tcp_usage();
                } else if (strcmp(name, "flags") == 0) {
                        if (flags_aton(value, &tcp->th_flags) < 0)
                                tcp_usage();
                } else if (strcmp(name, "seq") == 0) {
                        if (seq_aton(value, &tcp->th_seq) < 0)
                                tcp_usage();
                } else if (strcmp(name, "ack") == 0) {
                        if (seq_aton(value, &tcp->th_ack) < 0)
                                tcp_usage();
                } else if (strcmp(name, "win") == 0) {
                        if (port_aton(value, &tcp->th_win) < 0)
                                tcp_usage();
                } else if (strcmp(name, "urp") == 0) {
                        if (port_aton(value, &tcp->th_urp) < 0)
                                tcp_usage();
                } else
                        tcp_usage();
        }
        argc -= c;
        argv += c;
        
        if (argc != 0)
                tcp_usage();

        p = buf + TCP_HDR_LEN;
        
        if (!isatty(STDIN_FILENO)) {
                len = sizeof(buf) - (p - buf);
                while ((c = read(STDIN_FILENO, p, len)) > 0) {
                        p += c;
                        len -= c;
                }
        }
        len = p - buf;
        
        if (write(STDOUT_FILENO, buf, len) != len)
                err(1, "write");

        return (0);
}

struct mod mod_tcp = {
        "tcp",
        MOD_TYPE_ENCAP,
        &tcp_main
};

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