eth.c

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/*
 * eth.c
 *
 * Copyright (c) 2001 Dug Song <dugsong@monkey.org>
 *
 * $Id: eth.c,v 1.6 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 <unistd.h>

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

void
eth_usage(void)
{
        fprintf(stderr, "Usage: dnet eth [type|src|dst <value>] ... \n");
        exit(1);
}

int
eth_main(int argc, char *argv[])
{
        struct eth_hdr *eth;
        struct addr addr;
        u_char *p, buf[ETH_LEN_MAX];    /* XXX */
        char *name, *value;
        int c, len;

        eth = (struct eth_hdr *)buf;
        memset(eth, 0, sizeof(*eth));
        eth->eth_type = htons(ETH_TYPE_IP);

        for (c = 1; c + 1 < argc; c += 2) {
                name = argv[c];
                value = argv[c + 1];

                if (strcmp(name, "type") == 0) {
                        if (type_aton(value, &eth->eth_type) < 0)
                                eth_usage();
                } else if (strcmp(name, "src") == 0) {
                        if (addr_aton(value, &addr) < 0)
                                eth_usage();
                        memcpy(&eth->eth_src, &addr.addr_eth, ETH_ADDR_LEN);
                } else if (strcmp(name, "dst") == 0) {
                        if (addr_aton(value, &addr) < 0)
                                eth_usage();
                        memcpy(&eth->eth_dst, &addr.addr_eth, ETH_ADDR_LEN);
                } else
                        eth_usage();
        }
        argc -= c;
        argv += c;

        if (argc != 0)
                eth_usage();
        
        if (isatty(STDIN_FILENO))
                errx(1, "can't read Ethernet payload from tty");
        
        p = buf + ETH_HDR_LEN;
        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_eth = {
        "eth",
        MOD_TYPE_ENCAP,
        eth_main
};

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