Add rough parsing of IP packets

layer4.py

@@ -0,0 +1,34 @@
+# GNU General Public License Version 3
+
+def parseIPpackage(s, i):
+    version = s[i + 0] >> 4
+    headerlength = (s[i + 0] & 0xf) * 4
+    totallength = int.from_bytes([s[i + 2], s[i + 3]], 'big')
+    identification = int.from_bytes([s[i + 4], s[i + 5]], 'big')
+    protocol = s[i + 9]
+    sourceip = int.from_bytes([s[i + 12], s[i + 13], s[i + 14], s[i + 15]], 'big')
+    destinationip = int.from_bytes([s[i + 16], s[i + 17], s[i + 18], s[i + 19]], 'big')
+    print(str(version) + ' ' + str(headerlength) + ' ' + str(totallength) + ' ' + str(identification) + ' ' + str(protocol) + ' ' + hex(sourceip) + ' ' + hex(destinationip))
+    return (totallength, s[i + headerlength + 8:i + totallength - headerlength + 1])
+
+def parseIPpackages(stream):
+    stream = bytes(stream)
+    allcontent = bytearray()
+    num = 1
+    i = 0
+    while i < len(stream):
+        print(str(num) + '.: ' + str(i))
+        (length, content) = parseIPpackage(stream, i)
+        i += length
+        allcontent.extend(content)
+        num += 1
+    return allcontent
+
+
+if __name__ == '__main__':
+    import ascii85
+
+    payload = ascii85.loadpayload('layers/layer4.txt')
+    decoded = ascii85.decode(payload)
+    decoded = parseIPpackages(decoded)
+    print(decoded)