decode_hex.c

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/*
 * decode_hex.c
 *
 * Hex dump, for debugging.
 *
 * Copyright (c) 2000 Dug Song <dugsong@monkey.org>
 *
 * $Id: decode_hex.c,v 1.5 2001/03/15 08:32:59 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));
}