decode_aim.c

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/*
 * decode_aim.c
 *
 * AOL Instant Messenger (and ICQ2000).
 * 
 * Copyright (c) 2000 Dug Song <dugsong@monkey.org>
 *
 * $Id: decode_aim.c,v 1.5 2001/03/15 08:32:59 dugsong Exp $
 */
 
#include "config.h"
 
#include <sys/types.h>
 
#include <stdio.h>
#include <string.h>
 
#include "hex.h"
#include "buf.h"
#include "decode.h"
 
struct flap {
    u_char  start;
    u_char  channel;
    u_short seqnum;
    u_short datalen;
};
 
static char *aim_xor1 = "Tic/Toc";
 
static u_char aim_xor2[] = {
    0xf3, 0x26, 0x81, 0xc4, 0x39, 0x86, 0xdb, 0x92,
    0x71, 0xa3, 0xb9, 0xe6, 0x53, 0x7a, 0x95, 0x7c
};
 
int
decode_aim(u_char *buf, int len, u_char *obuf, int olen)
{
    struct buf *msg, inbuf, outbuf;
    struct flap *flap;
    u_char c, *p;
    int i, j;
 
    buf_init(&inbuf, buf, len);
    buf_init(&outbuf, obuf, olen);
 
    if (buf_cmp(&inbuf, "FLAPON\r\n\r\n", 10) == 0)
        buf_skip(&inbuf, 10);
 
    while (buf_len(&inbuf) > sizeof(*flap)) {
        flap = (struct flap *)buf_ptr(&inbuf);
        flap->datalen = ntohs(flap->datalen);
 
        i = sizeof(*flap) + flap->datalen;
 
        if ((msg = buf_tok(&inbuf, NULL, i)) == NULL)
            break;
 
        buf_skip(msg, sizeof(*flap));
 
        if (buf_cmp(msg, "toc_signon ", 11) == 0) {
            msg->base[msg->end - 1] = '\0';
            p = buf_ptr(msg);
            
            for (i = 0; i < 4; i++) {
                if ((j = strcspn(p, " ")) > 0)
                    p += (j + 1);
            }
            if (strtok(p, " ") == NULL)
                continue;
 
            buf_putf(&outbuf, "%s ", buf_ptr(msg));
            
            i = strlen(p);
            j = hex_decode(p, i, p, i);
 
            for (i = 0; i < j; i++)
                p[i] = p[i] ^ aim_xor1[i % 7];
            p[i] = '\0';
 
            buf_putf(&outbuf, "[%s]\n", p);
        }
        else if (flap->start == 0x2a && flap->channel == 0x01 &&
             buf_cmp(msg, "\x00\x00\x00\x01", 4) == 0) {
            buf_skip(msg, 7);
            
            buf_get(msg, &c, 1);
            p = buf_ptr(msg);
 
            if (c == 0 || buf_skip(msg, c + 3) < 0)
                continue;
 
            p[c] = '\0';
            
            buf_get(msg, &c, 1);
 
            if (buf_len(msg) < c + 1)
                continue;
 
            buf_putf(&outbuf, "%s\n", p);
            
            p = buf_ptr(msg);
 
            for (i = 0; i < c; i++) {
                p[i] = p[i] ^ aim_xor2[i % sizeof(aim_xor2)];
            }
            p[i] = '\0';
            
            buf_putf(&outbuf, "%s\n", p);
            
            break;
        }       
    }
    buf_end(&outbuf);
    
    return (buf_len(&outbuf));
}