Fix/crash corrupted iso (#154)

* check if SUSP is formatted correctly in order to prevent a crash

* update code style

* finish code refinement

XADISO9660Parser.m

@@ -643,15 +643,35 @@ case TypeID('A','S'):
 						break;
 
 						case TypeID('C','E'):
-						{
-							if(length!=28) break;
-							if(system[pos+3]!=1) break;
-
-							uint32_t block=CSUInt32LE(&system[pos+4]);
-							uint32_t offset=CSUInt32LE(&system[pos+12]);
-							nextoffset=block*2048+offset;
-
-							nextlength=CSUInt32LE(&system[pos+20]);
+                        {
+                            if (length != 28) break;
+                            if (system[pos+3] != 1) break;
+
+                            /**
+                             This region is a SUSP, define in SUSP IEEE P1281 section 5.1, which says that
+                             the next fields shall be recorded according to ISO 9660:1988 Format section 7.3.3.
+                             From ISO 9660:1988 7.3.3:
+                             "A numerical value represented by the hexadecimal representation (st uv wx yz)
+                             shall be recorded in an eight- byte field as (yz wx uv st st uv wx yz)."
+                             
+                             We can read the next fields in BigEndian and LittleEndian format
+                             and compare then in order to determine if the SUSP CE block is corrupted.
+                             */
+                            uint32_t blockLE = CSUInt32LE(&system[pos+4]);
+                            uint32_t blockBE = CSUInt32BE(&system[pos+8]);
+
+                            uint32_t offsetLE = CSUInt32LE(&system[pos+12]);
+                            uint32_t offsetBE = CSUInt32BE(&system[pos+16]);
+
+                            uint32_t lengthLE = CSUInt32LE(&system[pos+20]);
+                            uint32_t lengthBE = CSUInt32BE(&system[pos+24]);
+
+                            if (blockLE != blockBE || offsetLE != offsetBE || lengthLE != lengthBE) {
+                                break;
+                            }
+
+                            nextoffset = blockLE * 2048 + offsetLE;
+                            nextlength = lengthLE;
 						}
 						break;