File: binhex.c

package info (click to toggle)
clamav 0.98.7+dfsg-0+deb6u2
  • links: PTS, VCS
  • area: main
  • in suites: squeeze-lts
  • size: 60,204 kB
  • ctags: 49,129
  • sloc: cpp: 267,090; ansic: 152,211; sh: 35,196; python: 2,630; makefile: 2,220; perl: 1,690; pascal: 1,218; lisp: 184; csh: 117; xml: 38; asm: 32; exp: 4
file content (265 lines) | stat: -rw-r--r-- 7,943 bytes parent folder | download | duplicates (2)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
/*
 *  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"
#include "binhex.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;
    const uint8_t *encoded;
    uint8_t 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;
    }

    memset(decoded, 0, 24);

    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++;
		    if (lseek(datafd, 0, SEEK_SET) == -1) {
                cli_dbgmsg("cli_binhex: call to lseek() has failed\n");
                ret = CL_ESEEK;
                break;
            }
		    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) {
		    if (lseek(resfd, 0, SEEK_SET) == -1) {
                cli_dbgmsg("cli_binhex: call to lseek() has failed\n");
                ret = CL_ESEEK;
                break;
            }
		    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");
		    if (lseek(datafd, 0, SEEK_SET) == -1) {
                cli_dbgmsg("cli_binhex: call to lseek() has failed\n");
                ret = CL_ESEEK;
                break;
            }
		    ret = cli_magic_scandesc(datafd, ctx);
		} else if(write_phase == IN_RES) {
		    cli_dbgmsg("cli_binhex: scanning partially extracted resource fork\n");
		    if (lseek(resfd, 0, SEEK_SET) == -1) {
                cli_dbgmsg("cli_binhex: call to lseek() has failed\n");
                ret = CL_ESEEK;
                break;
            }
		    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;
}