static USHORT Unpack_Track(UCHAR *b1, UCHAR *b2, USHORT pklen2, USHORT unpklen, UCHAR cmode, UCHAR flags, USHORT number, USHORT pklen1, USHORT usum1, int enc)
{
USHORT r, err = NO_PROBLEM;
static USHORT pass;
int maybeencrypted;
int pwrounds;
UCHAR *tmp;
USHORT prevpass = 0;
if (passfound) {
if (number != 80)
dms_decrypt(b1, pklen1, b1);
r = Unpack_Track_2(b1, b2, pklen2, unpklen, cmode, flags);
if (r == NO_PROBLEM) {
if (usum1 == dms_Calc_CheckSum(b2,(ULONG)unpklen))
return NO_PROBLEM;
}
log_error(number);
if (passretries <= 0)
return ERR_CSUM;
}
passretries--;
pwrounds = 0;
maybeencrypted = 0;
tmp = (unsigned char*)malloc (pklen1);
memcpy (tmp, b1, pklen1);
memset(b2, 0, unpklen);
for (;;) {
r = Unpack_Track_2(b1, b2, pklen2, unpklen, cmode, flags);
if (r == NO_PROBLEM) {
if (usum1 == dms_Calc_CheckSum(b2,(ULONG)unpklen)) {
passfound = maybeencrypted;
if (passfound)
write_log (L"DMS: decryption key = 0x%04X\n", prevpass);
err = NO_PROBLEM;
pass = prevpass;
break;
}
}
if (number == 80 || !enc) {
err = ERR_CSUM;
break;
}
maybeencrypted = 1;
prevpass = pass;
PWDCRC = pass;
pass++;
dms_decrypt(b1, pklen1, tmp);
pwrounds++;
if (pwrounds == 65536) {
err = ERR_CSUM;
passfound = 0;
break;
}
}
free (tmp);
return err;
}
static USHORT Process_Track(struct zfile *fi, struct zfile *fo, UCHAR *b1, UCHAR *b2, USHORT cmd, USHORT opt, USHORT pwd){
USHORT hcrc, dcrc, usum, number, pklen1, pklen2, unpklen, l, r;
UCHAR cmode, flags;
l = (USHORT)zfile_fread(b1,1,THLEN,fi);
if (l != THLEN) {
if (l==0)
return DMS_FILE_END;
else
return ERR_SREAD;
}
/* "TR" identifies a Track Header */
if ((b1[0] != 'T')||(b1[1] != 'R')) return ERR_NOTTRACK;
/* Track Header CRC */
hcrc = (USHORT)((b1[THLEN-2] << 8) | b1[THLEN-1]);
if (CreateCRC(b1,(ULONG)(THLEN-2)) != hcrc) return ERR_THCRC;
number = (USHORT)((b1[2] << 8) | b1[3]); /* Number of track */
pklen1 = (USHORT)((b1[6] << 8) | b1[7]); /* Length of packed track data as in archive */
pklen2 = (USHORT)((b1[8] << 8) | b1[9]); /* Length of data after first unpacking */
unpklen = (USHORT)((b1[10] << 8) | b1[11]); /* Length of data after subsequent rle unpacking */
flags = b1[12]; /* control flags */
cmode = b1[13]; /* compression mode used */
usum = (USHORT)((b1[14] << 8) | b1[15]); /* Track Data CheckSum AFTER unpacking */
dcrc = (USHORT)((b1[16] << 8) | b1[17]); /* Track Data CRC BEFORE unpacking */
if (cmd == CMD_VIEWFULL) {
if (number==80)
write_log (" FileID ");
else if (number==0xffff)
write_log (" Banner ");
else if ((number==0) && (unpklen==1024))
write_log (" FakeBB ");
else
write_log (" %2d ",(short)number);
write_log ("%5d %5d %s %04X %04X %04X %0d\n", pklen1, unpklen, modes[cmode], usum, hcrc, dcrc, flags);
}
if ((pklen1 > TRACK_BUFFER_LEN) || (pklen2 >TRACK_BUFFER_LEN) || (unpklen > TRACK_BUFFER_LEN)) return ERR_BIGTRACK;
if (zfile_fread(b1,1,(size_t)pklen1,fi) != pklen1) return ERR_SREAD;
if (CreateCRC(b1,(ULONG)pklen1) != dcrc) return ERR_TDCRC;
/* track 80 is FILEID.DIZ, track 0xffff (-1) is Banner */
/* and track 0 with 1024 bytes only is a fake boot block with more advertising */
/* FILE_ID.DIZ is never encrypted */
if (pwd && (number!=80)) dms_decrypt(b1,pklen1);
if ((cmd == CMD_UNPACK) && (number<80) && (unpklen>2048)) {
r = Unpack_Track(b1, b2, pklen2, unpklen, cmode, flags);
if (r != NO_PROBLEM)
if (pwd)
return ERR_BADPASSWD;
else
return r;
if (usum != Calc_CheckSum(b2,(ULONG)unpklen))
if (pwd)
return ERR_BADPASSWD;
else
return ERR_CSUM;
if (zfile_fwrite(b2,1,(size_t)unpklen,fo) != unpklen) return ERR_CANTWRITE;
}
if ((cmd == CMD_SHOWBANNER) && (number == 0xffff)){
r = Unpack_Track(b1, b2, pklen2, unpklen, cmode, flags);
if (r != NO_PROBLEM)
if (pwd)
return ERR_BADPASSWD;
else
return r;
if (usum != Calc_CheckSum(b2,(ULONG)unpklen))
if (pwd)
return ERR_BADPASSWD;
else
return ERR_CSUM;
printbandiz(b2,unpklen);
}
if ((cmd == CMD_SHOWDIZ) && (number == 80)) {
r = Unpack_Track(b1, b2, pklen2, unpklen, cmode, flags);
if (r != NO_PROBLEM) return r;
if (usum != Calc_CheckSum(b2,(ULONG)unpklen)) return ERR_CSUM;
printbandiz(b2,unpklen);
}
return NO_PROBLEM;
}
