400 lines
12 KiB
C
400 lines
12 KiB
C
/*
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* Copyright (C) 2013-2022 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
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* Copyright (C) 2007-2013 Sourcefire, Inc.
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*
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* Authors: Nigel Horne
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*
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* Acknowledgements: The algorithm was based on
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* kdepim/ktnef/lib/ktnefparser.cpp from KDE.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301, USA.
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*/
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#if HAVE_CONFIG_H
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#include "clamav-config.h"
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#endif
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#include <stdio.h>
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#include <fcntl.h>
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include "clamav.h"
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#include "others.h"
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#include "mbox.h"
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#include "tnef.h"
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static int tnef_message(fmap_t *map, off_t *pos, uint16_t type, uint16_t tag, int32_t length, off_t fsize);
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static int tnef_attachment(fmap_t *map, off_t *pos, uint16_t type, uint16_t tag, int32_t length, const char *dir, fileblob **fbref, off_t fsize);
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static int tnef_header(fmap_t *map, off_t *pos, uint8_t *part, uint16_t *type, uint16_t *tag, int32_t *length);
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#define TNEF_SIGNATURE 0x223E9f78
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#define LVL_MESSAGE 0x01
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#define LVL_ATTACHMENT 0x02
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#define attMSGCLASS 0x8008
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#define attBODY 0x800c
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#define attATTACHDATA 0x800f /* Attachment Data */
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#define attATTACHTITLE 0x8010 /* Attachment File Name */
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#define attDATEMODIFIED 0x8020
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#define attTNEFVERSION 0x9006
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#define attOEMCODEPAGE 0x9007
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#define host16(v) le16_to_host(v)
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#define host32(v) le32_to_host(v)
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/* a TNEF file must be at least this size */
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#define MIN_SIZE (sizeof(uint32_t) + sizeof(uint16_t))
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int cli_tnef(const char *dir, cli_ctx *ctx)
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{
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uint32_t i32;
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uint16_t i16;
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fileblob *fb;
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int ret, alldone;
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off_t fsize, pos = 0;
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fsize = ctx->fmap->len;
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if (fsize < (off_t)MIN_SIZE) {
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cli_dbgmsg("cli_tngs: file too small, ignoring\n");
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return CL_CLEAN;
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}
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if (fmap_readn(ctx->fmap, &i32, pos, sizeof(uint32_t)) != sizeof(uint32_t)) {
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/* The file is at least MIN_SIZE bytes, so it "can't" fail */
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return CL_EREAD;
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}
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pos += sizeof(uint32_t);
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if (host32(i32) != TNEF_SIGNATURE) {
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return CL_EFORMAT;
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}
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if (fmap_readn(ctx->fmap, &i16, pos, sizeof(uint16_t)) != sizeof(uint16_t)) {
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/* The file is at least MIN_SIZE bytes, so it "can't" fail */
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return CL_EREAD;
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}
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pos += sizeof(uint16_t);
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fb = NULL;
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ret = CL_CLEAN; /* we don't know if it's clean or not :-) */
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alldone = 0;
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do {
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uint8_t part = 0;
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uint16_t type = 0, tag = 0;
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int32_t length = 0;
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switch (tnef_header(ctx->fmap, &pos, &part, &type, &tag, &length)) {
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case 0:
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alldone = 1;
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break;
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case 1:
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break;
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default:
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/*
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* Assume truncation, not file I/O error
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*/
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cli_warnmsg("cli_tnef: file truncated, returning CLEAN\n");
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ret = CL_CLEAN;
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alldone = 1;
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break;
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}
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if (length == 0)
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continue;
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if (length < 0) {
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cli_warnmsg("Corrupt TNEF header detected - length %d\n",
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(int)length);
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ret = CL_EFORMAT;
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break;
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}
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if (alldone)
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break;
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switch (part) {
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case LVL_MESSAGE:
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cli_dbgmsg("TNEF - found message\n");
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if (fb != NULL) {
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fileblobDestroy(fb);
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fb = NULL;
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}
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fb = fileblobCreate();
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if (tnef_message(ctx->fmap, &pos, type, tag, length, fsize) != 0) {
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cli_dbgmsg("TNEF: Error reading TNEF message\n");
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ret = CL_EFORMAT;
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alldone = 1;
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}
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break;
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case LVL_ATTACHMENT:
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cli_dbgmsg("TNEF - found attachment\n");
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if (tnef_attachment(ctx->fmap, &pos, type, tag, length, dir, &fb, fsize) != 0) {
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cli_dbgmsg("TNEF: Error reading TNEF attachment\n");
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ret = CL_EFORMAT;
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alldone = 1;
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}
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break;
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case 0:
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break;
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default:
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cli_warnmsg("TNEF - unknown level %d tag 0x%x\n", (int)part, (int)tag);
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/*
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* Dump the file incase it was part of an
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* email that's about to be deleted
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*/
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if (cli_debug_flag) {
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int fout = -1;
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char *filename = cli_gentemp(ctx->sub_tmpdir);
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char buffer[BUFSIZ];
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if (filename)
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fout = open(filename, O_WRONLY | O_CREAT | O_EXCL | O_TRUNC | O_BINARY, 0600);
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if (fout >= 0) {
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size_t count;
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cli_warnmsg("Saving dump to %s: refer to https://docs.clamav.net/manual/Installing.html\n", filename);
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pos = 0;
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while ((count = fmap_readn(ctx->fmap, buffer, pos, sizeof(buffer))) != (size_t)-1) {
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pos += count;
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cli_writen(fout, buffer, count);
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}
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close(fout);
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}
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free(filename);
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}
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ret = CL_EFORMAT;
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alldone = 1;
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break;
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}
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} while (!alldone);
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if (fb) {
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cli_dbgmsg("cli_tnef: flushing final data\n");
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if (fileblobGetFilename(fb) == NULL) {
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cli_dbgmsg("Saving TNEF portion with an unknown name\n");
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fileblobSetFilename(fb, dir, "tnef");
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}
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fileblobDestroy(fb);
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fb = NULL;
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}
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cli_dbgmsg("cli_tnef: returning %d\n", ret);
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return ret;
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}
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static int
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tnef_message(fmap_t *map, off_t *pos, uint16_t type, uint16_t tag, int32_t length, off_t fsize)
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{
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off_t offset;
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#ifdef CL_DEBUG
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uint32_t i32;
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char *string;
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#else
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UNUSEDPARAM(map);
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#endif
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cli_dbgmsg("message tag 0x%x, type 0x%x, length %d\n", tag, type,
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(int)length);
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offset = *pos;
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/*
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* a lot of this stuff should be only discovered in debug mode...
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*/
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switch (tag) {
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case attBODY:
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cli_warnmsg("TNEF body not being scanned - if you believe this file contains a virus, submit it to www.clamav.net\n");
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break;
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#ifdef CL_DEBUG
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case attTNEFVERSION:
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/*assert(length == sizeof(uint32_t))*/
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if (fmap_readn(map, &i32, *pos, sizeof(uint32_t)) != sizeof(uint32_t))
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return -1;
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(*pos) += sizeof(uint32_t);
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i32 = host32(i32);
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cli_dbgmsg("TNEF version %d\n", i32);
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break;
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case attOEMCODEPAGE:
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/* 8 bytes, but just print the first 4 */
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/*assert(length == sizeof(uint32_t))*/
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if (fmap_readn(map, &i32, *pos, sizeof(uint32_t)) != sizeof(uint32_t))
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return -1;
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(*pos) += sizeof(uint32_t);
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i32 = host32(i32);
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cli_dbgmsg("TNEF codepage %d\n", i32);
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break;
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case attDATEMODIFIED:
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/* 14 bytes, long */
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break;
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case attMSGCLASS:
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if (length <= 0)
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return -1;
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string = cli_malloc(length + 1);
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if (string == NULL) {
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cli_errmsg("tnef_message: Unable to allocate memory for string\n");
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return -1;
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}
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if ((uint32_t)fmap_readn(map, string, *pos, (uint32_t)length) != (uint32_t)length) {
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free(string);
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return -1;
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}
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(*pos) += (uint32_t)length;
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string[length] = '\0';
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cli_dbgmsg("TNEF class %s\n", string);
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free(string);
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break;
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default:
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cli_dbgmsg("TNEF - unsupported message tag 0x%x type 0x%d length %d\n", tag, type, length);
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break;
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#endif
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}
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/*cli_dbgmsg("%lu %lu\n", (long)(offset + length), ftell(fp));*/
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if (!CLI_ISCONTAINED_2_0_TO(fsize, offset, length)) {
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cli_dbgmsg("TNEF: Incorrect length field in tnef_message\n");
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return -1;
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}
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(*pos) = offset + length;
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/* Checksum - TODO, verify */
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(*pos) += 2;
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return 0;
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}
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static int
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tnef_attachment(fmap_t *map, off_t *pos, uint16_t type, uint16_t tag, int32_t length, const char *dir, fileblob **fbref, off_t fsize)
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{
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uint32_t todo;
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off_t offset;
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char *string;
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cli_dbgmsg("attachment tag 0x%x, type 0x%x, length %d\n", tag, type,
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(int)length);
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offset = *pos;
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switch (tag) {
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case attATTACHTITLE:
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if (length <= 0)
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return -1;
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string = cli_malloc(length + 1);
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if (string == NULL) {
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cli_errmsg("tnef_attachment: Unable to allocate memory for string\n");
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return -1;
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}
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if ((uint32_t)fmap_readn(map, string, *pos, (uint32_t)length) != (uint32_t)length) {
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free(string);
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return -1;
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}
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(*pos) += (uint32_t)length;
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string[length] = '\0';
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cli_dbgmsg("TNEF filename %s\n", string);
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if (*fbref == NULL) {
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*fbref = fileblobCreate();
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if (*fbref == NULL) {
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free(string);
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return -1;
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}
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}
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fileblobSetFilename(*fbref, dir, string);
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free(string);
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break;
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case attATTACHDATA:
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if (*fbref == NULL) {
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*fbref = fileblobCreate();
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if (*fbref == NULL)
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return -1;
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}
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todo = length;
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while (todo) {
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unsigned char buf[BUFSIZ];
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size_t got = fmap_readn(map, buf, *pos, MIN(sizeof(buf), todo));
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if (got == 0 || got == (size_t)-1)
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break;
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(*pos) += (off_t)got;
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fileblobAddData(*fbref, buf, got);
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todo -= (uint32_t)got;
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}
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break;
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default:
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cli_dbgmsg("TNEF - unsupported attachment tag 0x%x type 0x%d length %d\n",
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tag, type, (int)length);
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break;
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}
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/*cli_dbgmsg("%lu %lu\n", (long)(offset + length), ftell(fp));*/
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if (!CLI_ISCONTAINED_2_0_TO(fsize, offset, length)) {
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cli_dbgmsg("TNEF: Incorrect length field in tnef_attachment\n");
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return -1;
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}
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(*pos) = offset + (off_t)length; /* shouldn't be needed */
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(*pos) += 2;
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return 0;
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}
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static int
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tnef_header(fmap_t *map, off_t *pos, uint8_t *part, uint16_t *type, uint16_t *tag, int32_t *length)
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{
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uint32_t i32;
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int rc;
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if (fmap_readn(map, part, *pos, 1) != 1)
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return 0;
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(*pos)++;
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if (*part == (uint8_t)0)
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return 0;
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rc = fmap_readn(map, &i32, *pos, sizeof(uint32_t));
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if (rc != sizeof(uint32_t)) {
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if (((*part == '\n') || (*part == '\r')) && (rc == 0)) {
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/*
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* trailing newline in the file, could be caused by
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* broken quoted-printable encoding in the source
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* message missing a final '='
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*/
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cli_dbgmsg("tnef_header: ignoring trailing newline\n");
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return 0;
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}
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return -1;
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}
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(*pos) += sizeof(uint32_t);
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i32 = host32(i32);
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*tag = (uint16_t)(i32 & 0xFFFF);
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*type = (uint16_t)((i32 & 0xFFFF0000) >> 16);
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if (fmap_readn(map, &i32, *pos, sizeof(uint32_t)) != sizeof(uint32_t))
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return -1;
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(*pos) += sizeof(uint32_t);
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*length = (int32_t)host32(i32);
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cli_dbgmsg("message tag 0x%x, type 0x%x, length %d\n",
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*tag, *type, (int)*length);
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return 1;
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}
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