decode_hex.c

一个网络工具包,可以嗅探email和http等数据包中的密码等信息.注意要先把libnet-1.0.2a.tar.gz和 libnids-1.16.tar.gz装上,不然会因为缺少库函数而无法编译和安

/*
  decode_hex.c

  Hex dump, for debugging.
  
  Copyright (c) 2000 Dug Song <[e-mail]>
  
  $Id: decode_hex.c,v 1.4 2000/11/09 22:29:39 dugsong Exp $
*/

#include "config.h"

#include <sys/param.h>
#include <sys/types.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include "buf.h"
#include "decode.h"

/* adapted from OpenBSD tcpdump: dump the buffer in emacs-hexl format */

int
decode_hex(u_char *buf, int len, u_char *obuf, int olen)
{
	struct buf inbuf, outbuf;
	u_int i, j, k;
	u_char c;

	buf_init(&inbuf, buf, len);
	buf_init(&outbuf, obuf, olen);
	
	while ((i = buf_len(&inbuf)) > 0) {
		i = i < 16 ? i : 16;
		k = buf_tell(&inbuf);
		
		buf_putf(&outbuf, "  %04x: ", k);
		
		for (j = 0; j < i; j++) {
			buf_get(&inbuf, &c, 1);
			buf_putf(&outbuf, "%02x", (u_int)c);
			if ((j % 2) == 1)
				buf_put(&outbuf, " ", 1);
		}
		for (; j < 16; j++) {
			buf_put(&outbuf, "   ", (j % 2) + 2);
		}
		buf_put(&outbuf, " ", 1);

		buf_seek(&inbuf, k, SEEK_SET);
		
		for (j = 0; j < i; j++) {
			buf_get(&inbuf, &c, 1);
			c = isprint(c) ? c : '.';
			buf_putf(&outbuf, "%c", c);
		}
		buf_put(&outbuf, "\n", 1);
	}
	buf_end(&outbuf);
	
	return (buf_len(&outbuf));
}