/*
* Copyright (C) 2010 Sourcefire, Inc.
*
* Authors: aCaB <acab@clamav.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*
*/
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#include <string.h>
#include "scanners.h"
#include "cltypes.h"
#include "others.h"
#include "clamav.h"
#include "fmap.h"
static const uint8_t hqxtbl[] = {
/* 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f */
/* 00-0f */ 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
/* 10-1f */ 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
/* 20-2f */ 0xff,0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0xff,0xff,
/* 30-3f */ 0x0d,0x0e,0x0f,0x10,0x11,0x12,0x13,0xff,0x14,0x15,0xff,0xff,0xff,0xff,0xff,0xff,
/* 40-4f */ 0x16,0x17,0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f,0x20,0x21,0x22,0x23,0x24,0xff,
/* 50-5f */ 0x25,0x26,0x27,0x28,0x29,0x2a,0x2b,0xff,0x2c,0x2d,0x2e,0x2f,0xff,0xff,0xff,0xff,
/* 60-6f */ 0x30,0x31,0x32,0x33,0x34,0x35,0x36,0xff,0x37,0x38,0x39,0x3a,0x3b,0x3c,0xff,0xff,
/* 70-7f */ 0x3d,0x3e,0x3f,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff
};
#define BH_FLUSH_SZ (BUFSIZ - 256)
int cli_binhex(cli_ctx *ctx) {
fmap_t *map = *ctx->fmap;
uint8_t *encoded, decoded[BUFSIZ], spare_bits, last_byte=0, this_byte, offset=0;
size_t enc_done=0, enc_todo=map->len;
unsigned int dec_done=0, chunksz = 0, chunkoff=0;
uint32_t datalen, reslen;
int in_data = 0, in_run = 0, datafd, resfd, ret = CL_CLEAN;
enum binhex_phase { IN_BANNER, IN_HEADER, IN_DATA, IN_LIMBO1, IN_LIMBO2, IN_RES } write_phase = IN_BANNER;
char *dname, *rname;
cli_dbgmsg("in cli_binhex\n");
if(!map->len) return CL_CLEAN;
if((ret = cli_gentempfd(ctx->engine->tmpdir, &dname, &datafd)) != CL_SUCCESS)
return ret;
if((ret = cli_gentempfd(ctx->engine->tmpdir, &rname, &resfd)) != CL_SUCCESS) {
close(datafd);
if(cli_unlink(dname)) ret = CL_EUNLINK;
free(dname);
return ret;
}
while(1) {
uint8_t b;
if(!enc_todo || dec_done >= BH_FLUSH_SZ) {
if(write_phase == IN_HEADER) {
uint32_t namelen = (uint32_t)decoded[0], hdrlen = 1 + namelen + 1 + 4 + 4 + 2;
if(!dec_done) {
cli_dbgmsg("cli_binhex: file is empty\n");
break;
}
datalen = (decoded[hdrlen]<<24) | (decoded[hdrlen+1]<<16) | (decoded[hdrlen+2]<<8) | decoded[hdrlen+3];
hdrlen += 4;
reslen = (decoded[hdrlen]<<24) | (decoded[hdrlen+1]<<16) | (decoded[hdrlen+2]<<8) | decoded[hdrlen+3];
hdrlen += 4 + 2;
decoded[namelen+1] = 0;
if(dec_done <= hdrlen) {
cli_dbgmsg("cli_binhex: file too short for header\n");
break;
}
if((ret = cli_checklimits("cli_binhex(data)", ctx, datalen, 0, 0)) != CL_CLEAN)
break;
if(cli_checklimits("cli_binhex(resources)", ctx, reslen, 0, 0) != CL_CLEAN)
reslen = 0;
cli_dbgmsg("cli_binhex: decoding '%s' - %u bytes of data to %s - %u bytes or resources to %s\n", decoded+1, datalen, dname, reslen, rname);
memmove(decoded, &decoded[hdrlen], dec_done - hdrlen);
dec_done -= hdrlen;
write_phase++;
}
if(dec_done && write_phase == IN_DATA) {
unsigned int todo = MIN(dec_done, datalen);
datalen -= todo;
dec_done -= todo;
if(cli_writen(datafd, decoded, todo)!=(int)todo) {
ret = CL_EWRITE;
break;
}
if(!datalen) {
write_phase++;
lseek(datafd, 0, SEEK_SET);
ret = cli_magic_scandesc(datafd, ctx);
if(ret == CL_VIRUS) break;
}
if(dec_done)
memmove(decoded, &decoded[todo], dec_done);
}
if(dec_done && write_phase == IN_LIMBO1) {
if(dec_done > 1) {
if(reslen<5) {
cli_dbgmsg("cli_binhex: skipping resources (too small)\n");
break;
}
dec_done-=2;
write_phase+=2;
if(dec_done)
memmove(decoded, &decoded[2], dec_done);
} else {
dec_done--;
write_phase++;
if(dec_done)
memmove(decoded, &decoded[1], dec_done);
}
}
if(dec_done && write_phase == IN_LIMBO2) {
if(reslen<5) {
cli_dbgmsg("cli_binhex: skipping resources (too small)\n");
break;
}
write_phase++;
if(--dec_done)
memmove(decoded, &decoded[1], dec_done);
}
if(dec_done && write_phase == IN_RES) {
unsigned int todo = MIN(dec_done, reslen);
reslen -= todo;
dec_done -= todo;
if(cli_writen(resfd, decoded, todo)!=(int)todo) {
ret = CL_EWRITE;
break;
}
if(!reslen) {
lseek(resfd, 0, SEEK_SET);
ret = cli_magic_scandesc(resfd, ctx);
break;
}
}
if(!enc_todo) {
if(write_phase == IN_DATA) {
cli_dbgmsg("cli_binhex: scanning partially extracted data fork\n");
lseek(datafd, 0, SEEK_SET);
ret = cli_magic_scandesc(datafd, ctx);
} else if(write_phase == IN_RES) {
cli_dbgmsg("cli_binhex: scanning partially extracted resource fork\n");
lseek(resfd, 0, SEEK_SET);
ret = cli_magic_scandesc(resfd, ctx);
}
break;
}
}
if(!chunksz) {
chunksz = MIN(enc_todo, map->pgsz);
encoded = fmap_need_off_once(map, enc_done, chunksz);
if(!encoded) {
ret = CL_EREAD;
break;
}
chunkoff = 0;
}
chunksz--;
b = encoded[chunkoff++];
enc_done++;
enc_todo--;
if((char)b == '\r' || (char)b == '\n') {
in_data = 1;
continue;
}
if(!in_data) continue;
if(write_phase == IN_BANNER) {
if((char)b != ':') {
cli_dbgmsg("cli_binhex: broken file (missing stream start identifier)\n");
break;
}
write_phase++;
}
if((char)b == ':')
continue;
if(b > 0x7f || (b = hqxtbl[b]) == 0xff) {
cli_dbgmsg("cli_binhex: Invalid character (%02x)\n", encoded[chunkoff-1]);
break;
}
switch((offset++) & 3) { /* 6 bits per char */
case 0: /* left-6h */
spare_bits = b<<2;
continue;
case 1: /* left-2l + middle-4h */
this_byte = spare_bits | (b>>4);
spare_bits = b<<4;
break;
case 2: /* middle-4l + right-2h */
this_byte = spare_bits | (b>>2);
spare_bits = b<<6;
break;
case 3: /* right-6l */
this_byte = spare_bits | b;
}
if(in_run) {
in_run = 0;
if(!this_byte)
this_byte = 0x90;
else {
while(--this_byte)
decoded[dec_done++] = last_byte;
continue;
}
} else if(this_byte == 0x90) {
in_run = 1;
continue;
}
decoded[dec_done++] = this_byte;
last_byte = this_byte;
}
close(datafd);
close(resfd);
if(!ctx->engine->keeptmp) {
if(cli_unlink(dname) && ret != CL_VIRUS) ret = CL_EUNLINK;
if(cli_unlink(rname) && ret != CL_VIRUS) ret = CL_EUNLINK;
}
free(dname);
free(rname);
return ret;
}