/*

  *  Copyright (C) 2013-2019 Cisco Systems, Inc. and/or its affiliates. All rights reserved.

  *  Copyright (C) 2007-2013 Sourcefire, Inc.

  *
  *  Authors: Alberto Wu

  *
  *  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.
  */
 
 /* FIXME: get a clue about masked stuff */
 
 #if HAVE_CONFIG_H
 #include "clamav-config.h"
 #endif
 
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
 #if HAVE_STRING_H
 #include <string.h>
 #endif
 #include <stdlib.h>
 #include <stdio.h>
 
 #include <zlib.h>
 #include "inflate64.h"
 #if HAVE_BZLIB_H
 #include <bzlib.h>
 #endif
 

 #include "explode.h"

 #include "others.h"
 #include "clamav.h"
 #include "scanners.h"
 #include "matcher.h"

 #include "fmap.h"

 #include "json_api.h"

 
 #define UNZIP_PRIVATE
 #include "unzip.h"
 

 // clang-format off
 #define ZIP_MAGIC_CENTRAL_DIRECTORY_RECORD_BEGIN    (0x02014b50)
 #define ZIP_MAGIC_CENTRAL_DIRECTORY_RECORD_END      (0x06054b50)
 #define ZIP_MAGIC_LOCAL_FILE_HEADER                 (0x04034b50)
 #define ZIP_MAGIC_FILE_BEGIN_SPLIT_OR_SPANNED       (0x08074b50)
 // clang-format on
 

 #define ZIP_MAX_NUM_OVERLAPPING_FILES 5
 

 #define ZIP_CRC32(r, c, b, l) \
     do {                      \
         r = crc32(~c, b, l);  \
         r = ~r;               \
     } while (0)

 static int wrap_inflateinit2(void *a, int b)
 {
     return inflateInit2(a, b);

 }
 

 /**
  * @brief uncompress file from zip
  *

  * @param src                           pointer to compressed data
  * @param csize                         size of compressed data
  * @param usize                         expected size of uncompressed data
  * @param method                        compression method
  * @param flags                         local header flags
  * @param[in,out] num_files_unzipped    current number of files that have been unzipped
  * @param[in,out] ctx                   scan context
  * @param tmpd                          temp directory path name
  * @param zcb                           callback function to invoke after extraction (default: scan)
  * @return cl_error_t                   CL_EPARSE = could not apply a password

  */
 static cl_error_t unz(
     const uint8_t *src,
     uint32_t csize,
     uint32_t usize,
     uint16_t method,
     uint16_t flags,
     unsigned int *num_files_unzipped,
     cli_ctx *ctx,
     char *tmpd,
     zip_cb zcb)

 {
     char name[1024], obuf[BUFSIZ];
     char *tempfile = name;

     int out_file, ret = CL_CLEAN;

     int res        = 1;
     size_t written = 0;

 
     if (tmpd) {

         snprintf(name, sizeof(name), "%s" PATHSEP "zip.%03u", tmpd, *num_files_unzipped);

         name[sizeof(name) - 1] = '\0';

     } else {

         if (!(tempfile = cli_gentemp(ctx->engine->tmpdir))) return CL_EMEM;
     }

     if ((out_file = open(tempfile, O_RDWR | O_CREAT | O_TRUNC | O_BINARY, S_IRUSR | S_IWUSR)) == -1) {

         cli_warnmsg("cli_unzip: failed to create temporary file %s\n", tempfile);
         if (!tmpd) free(tempfile);
         return CL_ETMPFILE;
     }
     switch (method) {
         case ALG_STORED:
             if (csize < usize) {

                 unsigned int fake = *num_files_unzipped + 1;

                 cli_dbgmsg("cli_unzip: attempting to inflate stored file with inconsistent size\n");
                 if ((ret = unz(src, csize, usize, ALG_DEFLATE, 0, &fake, ctx, tmpd, zcb)) == CL_CLEAN) {

                     (*num_files_unzipped)++;
                     res = fake - (*num_files_unzipped);

                 } else
                     break;
             }
             if (res == 1) {
                 if (ctx->engine->maxfilesize && csize > ctx->engine->maxfilesize) {
                     cli_dbgmsg("cli_unzip: trimming output size to maxfilesize (%lu)\n", (long unsigned int)ctx->engine->maxfilesize);
                     csize = ctx->engine->maxfilesize;
                 }

                 if (cli_writen(out_file, src, csize) != csize)

                     ret = CL_EWRITE;
                 else
                     res = 0;
             }
             break;
 
         case ALG_DEFLATE:
         case ALG_DEFLATE64: {
             union {
                 z_stream64 strm64;
                 z_stream strm;
             } strm;
             typedef int (*unz_init_)(void *, int);
             typedef int (*unz_unz_)(void *, int);
             typedef int (*unz_end_)(void *);
             unz_init_ unz_init;
             unz_unz_ unz_unz;
             unz_end_ unz_end;
             int wbits;
             void **next_in;
             void **next_out;
             unsigned int *avail_in;
             unsigned int *avail_out;
 
             if (method == ALG_DEFLATE64) {
                 unz_init  = (unz_init_)inflate64Init2;
                 unz_unz   = (unz_unz_)inflate64;
                 unz_end   = (unz_end_)inflate64End;
                 next_in   = (void *)&strm.strm64.next_in;
                 next_out  = (void *)&strm.strm64.next_out;
                 avail_in  = &strm.strm64.avail_in;
                 avail_out = &strm.strm64.avail_out;
                 wbits     = MAX_WBITS64;
             } else {
                 unz_init  = (unz_init_)wrap_inflateinit2;
                 unz_unz   = (unz_unz_)inflate;
                 unz_end   = (unz_end_)inflateEnd;
                 next_in   = (void *)&strm.strm.next_in;
                 next_out  = (void *)&strm.strm.next_out;
                 avail_in  = &strm.strm.avail_in;
                 avail_out = &strm.strm.avail_out;
                 wbits     = MAX_WBITS;
             }

             memset(&strm, 0, sizeof(strm));
 
             *next_in   = (void *)src;
             *next_out  = obuf;
             *avail_in  = csize;
             *avail_out = sizeof(obuf);
             if (unz_init(&strm, -wbits) != Z_OK) {
                 cli_dbgmsg("cli_unzip: zinit failed\n");
                 break;
             }
             while (1) {
                 while ((res = unz_unz(&strm, Z_NO_FLUSH)) == Z_OK) {
                 };
                 if (*avail_out != sizeof(obuf)) {
                     written += sizeof(obuf) - (*avail_out);
                     if (ctx->engine->maxfilesize && written > ctx->engine->maxfilesize) {
                         cli_dbgmsg("cli_unzip: trimming output size to maxfilesize (%lu)\n", (long unsigned int)ctx->engine->maxfilesize);
                         res = Z_STREAM_END;
                         break;
                     }

                     if (cli_writen(out_file, obuf, sizeof(obuf) - (*avail_out)) != (size_t)(sizeof(obuf) - (*avail_out))) {

                         cli_warnmsg("cli_unzip: falied to write %lu inflated bytes\n", (unsigned long int)sizeof(obuf) - (*avail_out));
                         ret = CL_EWRITE;
                         res = 100;
                         break;
                     }
                     *next_out  = obuf;
                     *avail_out = sizeof(obuf);
                     continue;
                 }
                 break;
             }
             unz_end(&strm);
             if ((res == Z_STREAM_END) | (res == Z_BUF_ERROR)) res = 0;
             break;
         }

 
 #if HAVE_BZLIB_H

 #ifdef NOBZ2PREFIX

 #define BZ2_bzDecompress bzDecompress
 #define BZ2_bzDecompressEnd bzDecompressEnd
 #define BZ2_bzDecompressInit bzDecompressInit

 #endif
 

         case ALG_BZIP2: {
             bz_stream strm;
             memset(&strm, 0, sizeof(strm));
             strm.next_in   = (char *)src;
             strm.next_out  = obuf;
             strm.avail_in  = csize;
             strm.avail_out = sizeof(obuf);
             if (BZ2_bzDecompressInit(&strm, 0, 0) != BZ_OK) {
                 cli_dbgmsg("cli_unzip: bzinit failed\n");
                 break;
             }
             while ((res = BZ2_bzDecompress(&strm)) == BZ_OK || res == BZ_STREAM_END) {
                 if (strm.avail_out != sizeof(obuf)) {
                     written += sizeof(obuf) - strm.avail_out;
                     if (ctx->engine->maxfilesize && written > ctx->engine->maxfilesize) {
                         cli_dbgmsg("cli_unzip: trimming output size to maxfilesize (%lu)\n", (unsigned long int)ctx->engine->maxfilesize);
                         res = BZ_STREAM_END;
                         break;
                     }

                     if (cli_writen(out_file, obuf, sizeof(obuf) - strm.avail_out) != (size_t)(sizeof(obuf) - strm.avail_out)) {

                         cli_warnmsg("cli_unzip: falied to write %lu bunzipped bytes\n", (long unsigned int)sizeof(obuf) - strm.avail_out);
                         ret = CL_EWRITE;
                         res = 100;
                         break;
                     }
                     strm.next_out  = obuf;
                     strm.avail_out = sizeof(obuf);
                     if (res == BZ_OK) continue; /* after returning BZ_STREAM_END once, decompress returns an error */
                 }
                 break;
             }
             BZ2_bzDecompressEnd(&strm);
             if (res == BZ_STREAM_END) res = 0;
             break;
         }

 #endif /* HAVE_BZLIB_H */
 

         case ALG_IMPLODE: {
             struct xplstate strm;
             strm.next_in   = (void *)src;
             strm.next_out  = (uint8_t *)obuf;
             strm.avail_in  = csize;
             strm.avail_out = sizeof(obuf);
             if (explode_init(&strm, flags) != EXPLODE_OK) {
                 cli_dbgmsg("cli_unzip: explode_init() failed\n");
                 break;
             }
             while ((res = explode(&strm)) == EXPLODE_OK) {
                 if (strm.avail_out != sizeof(obuf)) {
                     written += sizeof(obuf) - strm.avail_out;
                     if (ctx->engine->maxfilesize && written > ctx->engine->maxfilesize) {
                         cli_dbgmsg("cli_unzip: trimming output size to maxfilesize (%lu)\n", (unsigned long int)ctx->engine->maxfilesize);
                         res = 0;
                         break;
                     }

                     if (cli_writen(out_file, obuf, sizeof(obuf) - strm.avail_out) != (size_t)(sizeof(obuf) - strm.avail_out)) {

                         cli_warnmsg("cli_unzip: falied to write %lu exploded bytes\n", (unsigned long int)sizeof(obuf) - strm.avail_out);
                         ret = CL_EWRITE;
                         res = 100;
                         break;
                     }
                     strm.next_out  = (uint8_t *)obuf;
                     strm.avail_out = sizeof(obuf);
                     continue;
                 }
                 break;
             }
             break;
         }

         case ALG_LZMA:
             /* easy but there's not a single sample in the zoo */

 
 #if !HAVE_BZLIB_H

         case ALG_BZIP2:

 #endif

         case ALG_SHRUNK:
         case ALG_REDUCE1:
         case ALG_REDUCE2:
         case ALG_REDUCE3:
         case ALG_REDUCE4:
         case ALG_TOKENZD:
         case ALG_OLDTERSE:
         case ALG_RSVD1:
         case ALG_RSVD2:
         case ALG_RSVD3:
         case ALG_RSVD4:
         case ALG_RSVD5:
         case ALG_NEWTERSE:
         case ALG_LZ77:
         case ALG_WAVPACK:
         case ALG_PPMD:
             cli_dbgmsg("cli_unzip: unsupported method (%d)\n", method);
             break;
         default:
             cli_dbgmsg("cli_unzip: unknown method (%d)\n", method);
             break;
     }
 
     if (!res) {

         (*num_files_unzipped)++;

         cli_dbgmsg("cli_unzip: extracted to %s\n", tempfile);

         if (lseek(out_file, 0, SEEK_SET) == -1) {

             cli_dbgmsg("cli_unzip: call to lseek() failed\n");
             if (!(tmpd))
                 free(tempfile);

             close(out_file);

             return CL_ESEEK;
         }

         ret = zcb(out_file, tempfile, ctx);
         close(out_file);

         if (!ctx->engine->keeptmp)
             if (cli_unlink(tempfile)) ret = CL_EUNLINK;
         if (!tmpd) free(tempfile);
         return ret;

     }

     close(out_file);

     if (!ctx->engine->keeptmp)
         if (cli_unlink(tempfile)) ret = CL_EUNLINK;
     if (!tmpd) free(tempfile);
     cli_dbgmsg("cli_unzip: extraction failed\n");

     return ret;
 }
 

 /* zip update keys, taken from zip specification */
 static inline void zupdatekey(uint32_t key[3], unsigned char input)
 {
     unsigned char tmp[1];
 
     tmp[0] = input;
     ZIP_CRC32(key[0], key[0], tmp, 1);
 
     key[1] = key[1] + (key[0] & 0xff);
     key[1] = key[1] * 134775813 + 1;
 
     tmp[0] = key[1] >> 24;
     ZIP_CRC32(key[2], key[2], tmp, 1);
 }
 
 /* zip init keys */

 static inline void zinitkey(uint32_t key[3], struct cli_pwdb *password)

 {
     int i;
 

     /* initialize keys, these are specified but the zip specification */

     key[0] = 305419896L;
     key[1] = 591751049L;
     key[2] = 878082192L;
 
     /* update keys with password  */
     for (i = 0; i < password->length; i++)

         zupdatekey(key, password->passwd[i]);

 }
 
 /* zip decrypt byte */
 static inline unsigned char zdecryptbyte(uint32_t key[3])
 {
     unsigned short temp;
     temp = key[2] | 2;
     return ((temp * (temp ^ 1)) >> 8);
 }
 

 /**
  * @brief zip decrypt.
  *
  * TODO - search for strong encryption header (0x0017) and handle them
  *
  * @param src

  * @param csize                         size of compressed data; includes the decryption header
  * @param usize                         expected size of uncompressed data

  * @param local_header

  * @param[in,out] num_files_unzipped    current number of files that have been unzipped
  * @param[in,out] ctx                   scan context
  * @param tmpd                          temp directory path name
  * @param zcb                           callback function to invoke after extraction (default: scan)
  * @return cl_error_t                   CL_EPARSE = could not apply a password

  */
 static inline cl_error_t zdecrypt(
     const uint8_t *src,
     uint32_t csize,
     uint32_t usize,
     const uint8_t *local_header,
     unsigned int *num_files_unzipped,
     cli_ctx *ctx,
     char *tmpd,
     zip_cb zcb)

 {

     cl_error_t ret;
     int v = 0;
     uint32_t i;

     uint32_t key[3];

     uint8_t encryption_header[12]; /* encryption header buffer */

     struct cli_pwdb *password, *pass_any, *pass_zip;

 
     if (!ctx || !ctx->engine)

         return CL_ENULLARG;

     /* dconf */
     if (ctx->dconf && !(ctx->dconf->archive & ARCH_CONF_PASSWD)) {

         cli_dbgmsg("cli_unzip: decrypt - skipping encrypted file\n");
         return CL_SUCCESS;

     }

     pass_any = ctx->engine->pwdbs[CLI_PWDB_ANY];
     pass_zip = ctx->engine->pwdbs[CLI_PWDB_ZIP];

     while (pass_any || pass_zip) {

         password = pass_zip ? pass_zip : pass_any;
 
         zinitkey(key, password);
 
         /* decrypting the encryption header */

         memcpy(encryption_header, src, SIZEOF_ENCRYPTION_HEADER);

         for (i = 0; i < SIZEOF_ENCRYPTION_HEADER; i++) {
             encryption_header[i] ^= zdecryptbyte(key);
             zupdatekey(key, encryption_header[i]);

         }
 
         /* verify that the password is correct */

         if (LOCAL_HEADER_version > 20) { /* higher than 2.0 */
             uint16_t a = encryption_header[SIZEOF_ENCRYPTION_HEADER - 1];

             if (LOCAL_HEADER_flags & F_USEDD) {
                 cli_dbgmsg("cli_unzip: decrypt - (v%u) >> 0x%02x 0x%x (moddate)\n", LOCAL_HEADER_version, a, LOCAL_HEADER_mtime);
                 if (a == ((LOCAL_HEADER_mtime >> 8) & 0xff))

                     v = 1;
             } else {

                 cli_dbgmsg("cli_unzip: decrypt - (v%u) >> 0x%02x 0x%x (crc32)\n", LOCAL_HEADER_version, a, LOCAL_HEADER_crc32);
                 if (a == ((LOCAL_HEADER_crc32 >> 24) & 0xff))

                     v = 1;
             }
         } else {

             uint16_t a = encryption_header[SIZEOF_ENCRYPTION_HEADER - 1], b = encryption_header[SIZEOF_ENCRYPTION_HEADER - 2];

             if (LOCAL_HEADER_flags & F_USEDD) {
                 cli_dbgmsg("cli_unzip: decrypt - (v%u) >> 0x0000%02x%02x 0x%x (moddate)\n", LOCAL_HEADER_version, a, b, LOCAL_HEADER_mtime);
                 if ((b | (a << 8)) == (LOCAL_HEADER_mtime & 0xffff))

                     v = 1;
             } else {

                 cli_dbgmsg("cli_unzip: decrypt - (v%u) >> 0x0000%02x%02x 0x%x (crc32)\n", LOCAL_HEADER_version, encryption_header[SIZEOF_ENCRYPTION_HEADER - 1], encryption_header[SIZEOF_ENCRYPTION_HEADER - 2], LOCAL_HEADER_crc32);
                 if ((b | (a << 8)) == ((LOCAL_HEADER_crc32 >> 16) & 0xffff))

                     v = 1;
             }
         }
 
         if (v) {
             char name[1024], obuf[BUFSIZ];

             char *tempfile = name;
             size_t written = 0, total = 0;

             fmap_t *dcypt_map;
             const uint8_t *dcypt_zip;

             int out_file;

 
             cli_dbgmsg("cli_unzip: decrypt - password [%s] matches\n", password->name);
 
             /* output decrypted data to tempfile */
             if (tmpd) {

                 snprintf(name, sizeof(name), "%s" PATHSEP "zip.decrypt.%03u", tmpd, *num_files_unzipped);

                 name[sizeof(name) - 1] = '\0';
             } else {
                 if (!(tempfile = cli_gentemp(ctx->engine->tmpdir))) return CL_EMEM;
             }

             if ((out_file = open(tempfile, O_RDWR | O_CREAT | O_TRUNC | O_BINARY, S_IRUSR | S_IWUSR)) == -1) {

                 cli_warnmsg("cli_unzip: decrypt - failed to create temporary file %s\n", tempfile);
                 if (!tmpd) free(tempfile);
                 return CL_ETMPFILE;
             }
 
             for (i = 12; i < csize; i++) {
                 obuf[written] = src[i] ^ zdecryptbyte(key);
                 zupdatekey(key, obuf[written]);
 
                 written++;
                 if (written >= BUFSIZ) {

                     if (cli_writen(out_file, obuf, written) != written) {

                         ret = CL_EWRITE;
                         goto zd_clean;
                     }
                     total += written;
                     written = 0;
                 }
             }
             if (written) {

                 if (cli_writen(out_file, obuf, written) != written) {

                     ret = CL_EWRITE;
                     goto zd_clean;
                 }
                 total += written;
                 written = 0;
             }
 

             cli_dbgmsg("cli_unzip: decrypt - decrypted %zu bytes to %s\n", total, tempfile);

 
             /* decrypt data to new fmap -> buffer */

             if (!(dcypt_map = fmap(out_file, 0, total))) {

                 cli_warnmsg("cli_unzip: decrypt - failed to create fmap on decrypted file %s\n", tempfile);
                 ret = CL_EMAP;
                 goto zd_clean;
             }
 
             if (!(dcypt_zip = fmap_need_off_once(dcypt_map, 0, total))) {
                 cli_warnmsg("cli_unzip: decrypt - failed to acquire buffer on decrypted file %s\n", tempfile);
                 funmap(dcypt_map);
                 ret = CL_EREAD;
                 goto zd_clean;
             }
 
             /* call unz on decrypted output */

             ret = unz(dcypt_zip, csize - SIZEOF_ENCRYPTION_HEADER, usize, LOCAL_HEADER_method, LOCAL_HEADER_flags, num_files_unzipped, ctx, tmpd, zcb);

 
             /* clean-up and return */
             funmap(dcypt_map);
         zd_clean:

             close(out_file);

             if (!ctx->engine->keeptmp)

                 if (cli_unlink(tempfile)) {

                     if (!tmpd) free(tempfile);
                     return CL_EUNLINK;
                 }

             if (!tmpd) free(tempfile);

             return ret;
         }

         if (pass_zip)
             pass_zip = pass_zip->next;
         else
             pass_any = pass_any->next;

     }
 

     cli_dbgmsg("cli_unzip: decrypt - skipping encrypted file, no valid passwords\n");

     return CL_SUCCESS;
 }
 

 /**
  * @brief Parse, extract, and scan a file using the local file header.
  *

  * @param map                           fmap for the file
  * @param loff                          offset of the local file header
  * @param zsize                         size of the zip file
  * @param[in,out] num_files_unzipped    current number of files that have been unzipped
  * @param file_count                    current number of files that have been discovered
  * @param central_header                offset of central directory header
  * @param[out] ret                      The status code
  * @param[in,out] ctx                   scan context
  * @param tmpd                          temp directory path name
  * @param detect_encrypted              bool: if encrypted files should raise heuristic alert
  * @param zcb                           callback function to invoke after extraction (default: scan)
  * @param[out] file_local_header_size   (optional) size of the local file header
  * @param[out] file_local_data_size     (optional) size of the compressed local file data
  * @return unsigned int                 returns the size of the file header + file data, so zip file can be indexed without the central directory

  */
 static unsigned int parse_local_file_header(
     fmap_t *map,
     uint32_t loff,
     uint32_t zsize,
     unsigned int *num_files_unzipped,
     unsigned int file_count,
     const uint8_t *central_header, /* pointer to central header. */
     cl_error_t *ret,
     cli_ctx *ctx,
     char *tmpd,
     int detect_encrypted,

     zip_cb zcb,
     uint32_t *file_local_header_size,
     uint32_t *file_local_data_size)

 {

     const uint8_t *local_header, *zip;

     char name[256];
     uint32_t csize, usize;
     int virus_found = 0;
 

     if (!(local_header = fmap_need_off(map, loff, SIZEOF_LOCAL_HEADER))) {
         cli_dbgmsg("cli_unzip: local header - out of file\n");

         return 0;
     }

     if (LOCAL_HEADER_magic != ZIP_MAGIC_LOCAL_FILE_HEADER) {
         if (!central_header)
             cli_dbgmsg("cli_unzip: local header - wrkcomplete\n");

         else

             cli_dbgmsg("cli_unzip: local header - bad magic\n");
         fmap_unneed_off(map, loff, SIZEOF_LOCAL_HEADER);

         return 0;
     }
 

     zip = local_header + SIZEOF_LOCAL_HEADER;
     zsize -= SIZEOF_LOCAL_HEADER;

     if (zsize <= LOCAL_HEADER_flen) {
         cli_dbgmsg("cli_unzip: local header - fname out of file\n");
         fmap_unneed_off(map, loff, SIZEOF_LOCAL_HEADER);

         return 0;
     }
     if (ctx->engine->cdb || cli_debug_flag) {

         uint32_t nsize = (LOCAL_HEADER_flen >= sizeof(name)) ? sizeof(name) - 1 : LOCAL_HEADER_flen;

         const char *src;
         if (nsize && (src = fmap_need_ptr_once(map, zip, nsize))) {
             memcpy(name, zip, nsize);
             name[nsize] = '\0';
         } else
             name[0] = '\0';
     }

     zip += LOCAL_HEADER_flen;
     zsize -= LOCAL_HEADER_flen;

     cli_dbgmsg("cli_unzip: local header - ZMDNAME:%d:%s:%u:%u:%x:%u:%u:%u\n",
                ((LOCAL_HEADER_flags & F_ENCR) != 0), name, LOCAL_HEADER_usize, LOCAL_HEADER_csize, LOCAL_HEADER_crc32, LOCAL_HEADER_method, file_count, ctx->recursion);

     /* ZMDfmt virname:encrypted(0-1):filename(exact|*):usize(exact|*):csize(exact|*):crc32(exact|*):method(exact|*):fileno(exact|*):maxdepth(exact|*) */
 

     /* Scan file header metadata. */
     if (cli_matchmeta(ctx, name, LOCAL_HEADER_csize, LOCAL_HEADER_usize, (LOCAL_HEADER_flags & F_ENCR) != 0, file_count, LOCAL_HEADER_crc32, NULL) == CL_VIRUS) {

         *ret = CL_VIRUS;
         if (!SCAN_ALLMATCHES)
             return 0;
         virus_found = 1;
     }
 

     if (LOCAL_HEADER_flags & F_MSKED) {
         cli_dbgmsg("cli_unzip: local header - header has got unusable masked data\n");

         /* FIXME: need to find/craft a sample */

         fmap_unneed_off(map, loff, SIZEOF_LOCAL_HEADER);

         return 0;
     }
 

     if (detect_encrypted && (LOCAL_HEADER_flags & F_ENCR) && SCAN_HEURISTIC_ENCRYPTED_ARCHIVE) {

         cli_dbgmsg("cli_unzip: Encrypted files found in archive.\n");
         *ret = cli_append_virus(ctx, "Heuristics.Encrypted.Zip");
         if ((*ret == CL_VIRUS && !SCAN_ALLMATCHES) || *ret != CL_CLEAN) {

             fmap_unneed_off(map, loff, SIZEOF_LOCAL_HEADER);

             return 0;
         }
         virus_found = 1;
     }
 

     if (LOCAL_HEADER_flags & F_USEDD) {
         cli_dbgmsg("cli_unzip: local header - has data desc\n");
         if (!central_header) {
             fmap_unneed_off(map, loff, SIZEOF_LOCAL_HEADER);

             return 0;
         } else {

             usize = CENTRAL_HEADER_usize;
             csize = CENTRAL_HEADER_csize;

         }
     } else {

         usize = LOCAL_HEADER_usize;
         csize = LOCAL_HEADER_csize;

     }
 

     if (zsize <= LOCAL_HEADER_elen) {
         cli_dbgmsg("cli_unzip: local header - extra out of file\n");
         fmap_unneed_off(map, loff, SIZEOF_LOCAL_HEADER);

         return 0;
     }

     zip += LOCAL_HEADER_elen;
     zsize -= LOCAL_HEADER_elen;

     if (NULL != file_local_header_size)
         *file_local_header_size = zip - local_header;
     if (NULL != file_local_data_size)
         *file_local_data_size = csize;
 

     if (!csize) { /* FIXME: what's used for method0 files? csize or usize? Nothing in the specs, needs testing */

         cli_dbgmsg("cli_unzip: local header - skipping empty file\n");

     } else {
         if (zsize < csize) {

             cli_dbgmsg("cli_unzip: local header - stream out of file\n");
             fmap_unneed_off(map, loff, SIZEOF_LOCAL_HEADER);

             return 0;
         }

         if (LOCAL_HEADER_flags & F_ENCR) {

             if (fmap_need_ptr_once(map, zip, csize))

                 *ret = zdecrypt(zip, csize, usize, local_header, num_files_unzipped, ctx, tmpd, zcb);

         } else {
             if (fmap_need_ptr_once(map, zip, csize))

                 *ret = unz(zip, csize, usize, LOCAL_HEADER_method, LOCAL_HEADER_flags, num_files_unzipped, ctx, tmpd, zcb);

         }
         zip += csize;
         zsize -= csize;
     }
 
     if (virus_found != 0)
         *ret = CL_VIRUS;
 

     fmap_unneed_off(map, loff, SIZEOF_LOCAL_HEADER); /* unneed now. block is guaranteed to exists till the next need */
     if (LOCAL_HEADER_flags & F_USEDD) {

         if (zsize < 12) {

             cli_dbgmsg("cli_unzip: local header - data desc out of file\n");

             return 0;
         }
         zsize -= 12;
         if (fmap_need_ptr_once(map, zip, 4)) {

             if (cli_readint32(zip) == ZIP_MAGIC_FILE_BEGIN_SPLIT_OR_SPANNED) {

                 if (zsize < 4) {

                     cli_dbgmsg("cli_unzip: local header - data desc out of file\n");

                     return 0;
                 }
                 zip += 4;
             }
         }
         zip += 12;
     }

     return zip - local_header;

 }
 

 /**
  * @brief Parse, extract, and scan a file by iterating the central directory.
  *

  * @param map                           fmap for the file
  * @param coff                          offset of the file header in the central directory
  * @param zsize                         size of the zip file
  * @param[in,out] num_files_unzipped    current number of files that have been unzipped
  * @param file_count                    current number of files that have been discovered
  * @param[out] ret                      The status code
  * @param[in,out] ctx                   scan context
  * @param tmpd                          temp directory path name
  * @param requests                      (optional) structure use to search the zip for files by name
  * @return unsigned int                 returns the size of the file header in the central directory, or 0 if no more files
  * @param[out] file_local_offset        (optional) offset of the local file header
  * @param[out] file_local_header_size   (optional) size of the local file header
  * @param[out] file_local_data_size     (optional) size of the compressed local file data
  * @return unsigned int

  */
 static unsigned int parse_central_directory_file_header(
     fmap_t *map,
     uint32_t coff,
     uint32_t zsize,
     unsigned int *num_files_unzipped,
     unsigned int file_count,
     cl_error_t *ret,
     cli_ctx *ctx,
     char *tmpd,

     struct zip_requests *requests,
     uint32_t *file_local_offset,
     uint32_t *file_local_header_size,
     uint32_t *file_local_data_size)

 {
     char name[256];
     int last = 0;

     const uint8_t *central_header;

     int virus_found = 0;
 

     if (NULL != file_local_offset)
         *file_local_offset = 0;
     if (NULL != file_local_header_size)
         *file_local_header_size = 0;
     if (NULL != file_local_data_size)
         *file_local_data_size = 0;
 

     if (!(central_header = fmap_need_off(map, coff, SIZEOF_CENTRAL_HEADER)) || CENTRAL_HEADER_magic != ZIP_MAGIC_CENTRAL_DIRECTORY_RECORD_BEGIN) {
         if (central_header) fmap_unneed_ptr(map, central_header, SIZEOF_CENTRAL_HEADER);
         cli_dbgmsg("cli_unzip: central header - wrkcomplete\n");

         return 0;
     }

     coff += SIZEOF_CENTRAL_HEADER;

     cli_dbgmsg("cli_unzip: central header - flags %x - method %x - csize %x - usize %x - flen %x - elen %x - clen %x - disk %x - off %x\n",
                CENTRAL_HEADER_flags, CENTRAL_HEADER_method, CENTRAL_HEADER_csize, CENTRAL_HEADER_usize, CENTRAL_HEADER_flen, CENTRAL_HEADER_extra_len, CENTRAL_HEADER_comment_len, CENTRAL_HEADER_disk_num, CENTRAL_HEADER_off);

     if (zsize - coff <= CENTRAL_HEADER_flen) {
         cli_dbgmsg("cli_unzip: central header - fname out of file\n");

         last = 1;
     }
 
     name[0] = '\0';
     if (!last) {

         unsigned int size = (CENTRAL_HEADER_flen >= sizeof(name)) ? sizeof(name) - 1 : CENTRAL_HEADER_flen;

         const char *src   = fmap_need_off_once(map, coff, size);
         if (src) {
             memcpy(name, src, size);
             name[size] = '\0';

             cli_dbgmsg("cli_unzip: central header - fname: %s\n", name);

         }
     }

     coff += CENTRAL_HEADER_flen;

 
     /* requests do not supply a ctx; also prevent multiple scans */

     if (ctx && cli_matchmeta(ctx, name, CENTRAL_HEADER_csize, CENTRAL_HEADER_usize, (CENTRAL_HEADER_flags & F_ENCR) != 0, file_count, CENTRAL_HEADER_crc32, NULL) == CL_VIRUS)

         virus_found = 1;
 

     if (zsize - coff <= CENTRAL_HEADER_extra_len && !last) {
         cli_dbgmsg("cli_unzip: central header - extra out of file\n");

         last = 1;
     }

     coff += CENTRAL_HEADER_extra_len;

     if (zsize - coff < CENTRAL_HEADER_comment_len && !last) {
         cli_dbgmsg("cli_unzip: central header - comment out of file\n");

         last = 1;
     }

     coff += CENTRAL_HEADER_comment_len;

 
     if (!requests) {

         if (CENTRAL_HEADER_off < zsize - SIZEOF_LOCAL_HEADER) {

             if (NULL != file_local_offset)
                 *file_local_offset = CENTRAL_HEADER_off;
             parse_local_file_header(map,
                                     CENTRAL_HEADER_off,
                                     zsize - CENTRAL_HEADER_off,
                                     num_files_unzipped,
                                     file_count,
                                     central_header,
                                     ret,
                                     ctx,
                                     tmpd,
                                     1,
                                     zip_scan_cb,
                                     file_local_header_size,
                                     file_local_data_size);
         } else {

             cli_dbgmsg("cli_unzip: central header - local hdr out of file\n");

         }

     } else {
         int i;
         size_t len;
 
         if (!last) {
             for (i = 0; i < requests->namecnt; ++i) {

                 cli_dbgmsg("cli_unzip: central header - checking for %i: %s\n", i, requests->names[i]);

 
                 len = MIN(sizeof(name) - 1, requests->namelens[i]);
                 if (!strncmp(requests->names[i], name, len)) {
                     requests->match = 1;
                     requests->found = i;

                     requests->loff  = CENTRAL_HEADER_off;

                 }
             }
         }
     }
 
     if (virus_found == 1)
         *ret = CL_VIRUS;

     fmap_unneed_ptr(map, central_header, SIZEOF_CENTRAL_HEADER);

     return (last ? 0 : coff);

 }
 

 cl_error_t cli_unzip(cli_ctx *ctx)

 {

     unsigned int file_count = 0, num_files_unzipped = 0;
     cl_error_t ret = CL_CLEAN;

     uint32_t fsize, lhoff = 0, coff = 0;
     fmap_t *map = *ctx->fmap;
     char *tmpd;
     const char *ptr;
     int virus_found = 0;

 #if HAVE_JSON

     int toval = 0;

 #endif

     int bZipBombDetected                 = 0;
     uint32_t cur_file_local_offset       = 0;
     uint32_t cur_file_local_header_size  = 0;
     uint32_t cur_file_local_data_size    = 0;
     uint32_t prev_file_local_offset      = 0;
     uint32_t prev_file_local_header_size = 0;
     uint32_t prev_file_local_data_size   = 0;

     cli_dbgmsg("in cli_unzip\n");
     fsize = (uint32_t)map->len;
     if (sizeof(off_t) != sizeof(uint32_t) && (size_t)fsize != map->len) {
         cli_dbgmsg("cli_unzip: file too big\n");
         return CL_CLEAN;
     }

     if (fsize < SIZEOF_CENTRAL_HEADER) {

         cli_dbgmsg("cli_unzip: file too short\n");
         return CL_CLEAN;
     }
     if (!(tmpd = cli_gentemp(ctx->engine->tmpdir))) {
         return CL_ETMPDIR;
     }
     if (mkdir(tmpd, 0700)) {
         cli_dbgmsg("cli_unzip: Can't create temporary directory %s\n", tmpd);
         free(tmpd);
         return CL_ETMPDIR;
     }
 
     for (coff = fsize - 22; coff > 0; coff--) { /* sizeof(EOC)==22 */
         if (!(ptr = fmap_need_off_once(map, coff, 20)))
             continue;

         if (cli_readint32(ptr) == ZIP_MAGIC_CENTRAL_DIRECTORY_RECORD_END) {

             uint32_t chptr = cli_readint32(&ptr[16]);

             if (!CLI_ISCONTAINED(0, fsize, chptr, SIZEOF_CENTRAL_HEADER)) continue;

             coff = chptr;
             break;
         }
     }
 
     if (coff) {

         uint32_t nOverlappingFiles = 0;
 

         cli_dbgmsg("cli_unzip: central directory header offset: @%x\n", coff);

         while ((coff = parse_central_directory_file_header(map,
                                                            coff,
                                                            fsize,
                                                            &num_files_unzipped,
                                                            file_count + 1,
                                                            &ret,
                                                            ctx,
                                                            tmpd,
                                                            NULL,
                                                            &cur_file_local_offset,
                                                            &cur_file_local_header_size,
                                                            &cur_file_local_data_size))) {

             file_count++;
             if (ctx->engine->maxfiles && num_files_unzipped >= ctx->engine->maxfiles) {

                 cli_dbgmsg("cli_unzip: Files limit reached (max: %u)\n", ctx->engine->maxfiles);
                 ret = CL_EMAXFILES;
             }

 
             /*
              * Detect overlapping files and zip bombs.
              */
             if ((((cur_file_local_offset > prev_file_local_offset) && (cur_file_local_offset < prev_file_local_offset + prev_file_local_header_size + prev_file_local_data_size)) ||
                  ((prev_file_local_offset > cur_file_local_offset) && (prev_file_local_offset < cur_file_local_offset + cur_file_local_header_size + cur_file_local_data_size))) &&
                 (cur_file_local_header_size + cur_file_local_data_size > 0)) {
                 /* Overlapping file detected */
                 nOverlappingFiles++;
 
                 cli_dbgmsg("cli_unzip: Overlapping files detected.\n");
                 cli_dbgmsg("    previous file end:  %u\n", prev_file_local_offset + prev_file_local_header_size + prev_file_local_data_size);
                 cli_dbgmsg("    current file start: %u\n", cur_file_local_offset);
 
                 if (ZIP_MAX_NUM_OVERLAPPING_FILES < nOverlappingFiles) {
                     if (SCAN_HEURISTICS) {
                         ret         = cli_append_virus(ctx, "Heuristics.Zip.OverlappingFiles");
                         virus_found = 1;
                     } else {
                         ret = CL_EFORMAT;
                     }
                     bZipBombDetected = 1;
                 }
             }
             prev_file_local_offset      = cur_file_local_offset;
             prev_file_local_header_size = cur_file_local_header_size;
             prev_file_local_data_size   = cur_file_local_data_size;
 

 #if HAVE_JSON

             if (cli_json_timeout_cycle_check(ctx, &toval) != CL_SUCCESS) {
                 ret = CL_ETIMEOUT;
             }

 #endif

             if (ret != CL_CLEAN) {

                 if (ret == CL_VIRUS && SCAN_ALLMATCHES && !bZipBombDetected) {

                     ret         = CL_CLEAN;
                     virus_found = 1;
                 } else
                     break;
             }
         }
     } else
         cli_dbgmsg("cli_unzip: central not found, using localhdrs\n");
     if (virus_found == 1)
         ret = CL_VIRUS;

     if (num_files_unzipped <= (file_count / 4)) { /* FIXME: make up a sane ratio or remove the whole logic */
         file_count = 0;
         while ((ret == CL_CLEAN) &&
                (lhoff < fsize) &&

                (0 != (coff = parse_local_file_header(map,
                                                      lhoff,
                                                      fsize - lhoff,
                                                      &num_files_unzipped,
                                                      file_count + 1,
                                                      NULL,
                                                      &ret,
                                                      ctx,
                                                      tmpd,
                                                      1,
                                                      zip_scan_cb,
                                                      NULL,
                                                      NULL)))) {

             file_count++;

             lhoff += coff;
             if (SCAN_ALLMATCHES && ret == CL_VIRUS) {
                 ret         = CL_CLEAN;
                 virus_found = 1;
             }

             if (ctx->engine->maxfiles && num_files_unzipped >= ctx->engine->maxfiles) {

                 cli_dbgmsg("cli_unzip: Files limit reached (max: %u)\n", ctx->engine->maxfiles);
                 ret = CL_EMAXFILES;
             }

 #if HAVE_JSON

             if (cli_json_timeout_cycle_check(ctx, &toval) != CL_SUCCESS) {
                 ret = CL_ETIMEOUT;
             }

 #endif

         }

     }
 

     if (!ctx->engine->keeptmp) cli_rmdirs(tmpd);
     free(tmpd);

     if (ret == CL_CLEAN && virus_found)
         ret = CL_VIRUS;

     return ret;

 }
 

 cl_error_t unzip_single_internal(cli_ctx *ctx, off_t local_header_offset, zip_cb zcb)

 {

     cl_error_t ret = CL_CLEAN;
 
     unsigned int num_files_unzipped = 0;

     uint32_t fsize;
     fmap_t *map = *ctx->fmap;
 
     cli_dbgmsg("in cli_unzip_single\n");

     fsize = (uint32_t)(map->len - local_header_offset);
     if ((local_header_offset < 0) ||
         ((size_t)local_header_offset > map->len) ||
         ((sizeof(off_t) != sizeof(uint32_t)) && ((size_t)fsize != map->len - local_header_offset))) {
 

         cli_dbgmsg("cli_unzip: bad offset\n");
         return CL_CLEAN;
     }

     if (fsize < SIZEOF_LOCAL_HEADER) {

         cli_dbgmsg("cli_unzip: file too short\n");
         return CL_CLEAN;
     }
 

     parse_local_file_header(map,
                             local_header_offset,
                             fsize,
                             &num_files_unzipped,
                             0,
                             NULL,
                             &ret,
                             ctx,
                             NULL,
                             0,
                             zcb,
                             NULL,
                             NULL);

 
     return ret;

 }

 cl_error_t cli_unzip_single(cli_ctx *ctx, off_t local_header_offset)

 {

     return unzip_single_internal(ctx, local_header_offset, zip_scan_cb);

 }
 

 cl_error_t unzip_search_add(struct zip_requests *requests, const char *name, size_t nlen)

 {
     cli_dbgmsg("in unzip_search_add\n");
 
     if (requests->namecnt >= MAX_ZIP_REQUESTS) {
         cli_dbgmsg("DEBUGGING MESSAGE GOES HERE!\n");
         return CL_BREAK;
     }
 
     cli_dbgmsg("unzip_search_add: adding %s (len %llu)\n", name, (long long unsigned)nlen);
 

     requests->names[requests->namecnt]    = name;

     requests->namelens[requests->namecnt] = nlen;
     requests->namecnt++;
 
     return CL_SUCCESS;
 }
 

 cl_error_t unzip_search(cli_ctx *ctx, fmap_t *map, struct zip_requests *requests)

 {

     unsigned int file_count = 0;
     fmap_t *zmap            = map;

     size_t fsize;
     uint32_t coff = 0;
     const char *ptr;

     cl_error_t ret = CL_CLEAN;

 #if HAVE_JSON
     uint32_t toval = 0;
 #endif

     cli_dbgmsg("in unzip_search\n");

 
     if ((!ctx && !map) || !requests) {

         return CL_ENULLARG;
     }
 

     /* get priority to given map over *ctx->fmap */
     if (ctx && !map)
         zmap = *ctx->fmap;
     fsize = zmap->len;

     if (sizeof(off_t) != sizeof(uint32_t) && fsize != zmap->len) {

         cli_dbgmsg("unzip_search: file too big\n");
         return CL_CLEAN;
     }

     if (fsize < SIZEOF_CENTRAL_HEADER) {

         cli_dbgmsg("unzip_search: file too short\n");
         return CL_CLEAN;
     }
 

     for (coff = fsize - 22; coff > 0; coff--) { /* sizeof(EOC)==22 */
         if (!(ptr = fmap_need_off_once(zmap, coff, 20)))

             continue;

         if (cli_readint32(ptr) == ZIP_MAGIC_CENTRAL_DIRECTORY_RECORD_END) {

             uint32_t chptr = cli_readint32(&ptr[16]);

             if (!CLI_ISCONTAINED(0, fsize, chptr, SIZEOF_CENTRAL_HEADER)) continue;

             coff = chptr;

             break;
         }
     }
 

     if (coff) {

         cli_dbgmsg("unzip_search: central directory header offset: @%x\n", coff);

         while (ret == CL_CLEAN && (coff = parse_central_directory_file_header(zmap,
                                                                               coff,
                                                                               fsize,
                                                                               NULL,
                                                                               file_count + 1,
                                                                               &ret,
                                                                               ctx,
                                                                               NULL,
                                                                               requests,
                                                                               NULL,
                                                                               NULL,
                                                                               NULL))) {

             if (requests->match) {

                 ret = CL_VIRUS;

             }
 

             file_count++;
             if (ctx && ctx->engine->maxfiles && file_count >= ctx->engine->maxfiles) {

                 cli_dbgmsg("cli_unzip: Files limit reached (max: %u)\n", ctx->engine->maxfiles);

                 ret = CL_EMAXFILES;

             }

 #if HAVE_JSON

             if (ctx && cli_json_timeout_cycle_check(ctx, (int *)(&toval)) != CL_SUCCESS) {

                 ret = CL_ETIMEOUT;

             }
 #endif

         }
     } else {
         cli_dbgmsg("unzip_search: cannot locate central directory\n");
     }
 
     return ret;
 }
 

 cl_error_t unzip_search_single(cli_ctx *ctx, const char *name, size_t nlen, uint32_t *loff)

 {
     struct zip_requests requests;

     cl_error_t ret;

 
     cli_dbgmsg("in unzip_search_single\n");
     if (!ctx) {
         return CL_ENULLARG;
     }
 
     memset(&requests, 0, sizeof(struct zip_requests));
 
     if ((ret = unzip_search_add(&requests, name, nlen)) != CL_SUCCESS) {
         return ret;
     }
 
     if ((ret = unzip_search(ctx, NULL, &requests)) == CL_VIRUS) {
         *loff = requests.loff;
     }
 
     return ret;
 }