1 files changed, 96 insertions, 0 deletions
diff --git a/AEpy/AESession.py b/AEpy/AESession.py
new file mode 100644
index 0000000..145fff7
--- /dev/null
+++ b/AEpy/AESession.py
@@ -0,0 +1,96 @@
+import binascii
+import serial
+import struct
+
+
+class AESession:
+    def __init__(self, link):
+        self.link = link
+        self.seq = 1
+        self.sendInit()
+        self.packetsize = 512
+
+
+    def recvMsg(self):
+        rawHeader = self.link.recv(12)
+        if len(rawHeader) != 12:
+            print('recvMsg: len(rawHeader) == ' + str(len(rawHeader)) + ' data: ' + binascii.hexlify(rawHeader))
+        #assert len(rawHeader) == 12
+
+        (type, datalen, seq, crc) = struct.unpack('!HHLL', rawHeader)
+        assert crc == (binascii.crc32(rawHeader[0:8]) & 0xffffffff)
+        # TODO: Send PkRs if CRC mismatches
+
+        data = b''
+
+        if datalen > 0:
+            data = self.link.recv(datalen)
+            assert len(data) == datalen
+
+            # Note: Python calculates signed CRCs.
+            #       Thus, we parse the incoming CRC as signed.
+            datacrc = self.link.recv(4)
+            assert len(datacrc) == 4
+            (datacrc,) = struct.unpack('!L', datacrc)
+
+            assert datacrc == (binascii.crc32(data) & 0xffffffff)
+            # TODO: Send PkRs if CRC mismatches
+
+        self.link.send(b'PkOk')
+
+        # seq is currently ignored when receiving
+        return (type, data)
+
+
+    def sendMsg(self, type, data):
+        stream = struct.pack('!HHL', type, len(data), self.seq)
+        stream += struct.pack('!L', binascii.crc32(stream) & 0xffffffff)
+
+        if len(data) > 0:
+            stream += data
+            stream += struct.pack('!L', binascii.crc32(data) & 0xffffffff)
+
+        self.link.send(stream)
+
+        # TODO: Re-send on 'PkRs'
+        assert self.link.recv(4) == b'PkOk'
+
+        self.seq += 1;
+
+
+
+    def sendInit(self):
+        self.sendMsg(2, b'Cloanto(r)')
+        # TBD: Password support.
+        #      It is CRC32'd and the CRC is appended to the string above.
+
+        # TODO: Recover from desynced state
+        #if not self.isAcked():
+        #    self.sendAck()
+        #    return self.sendInit()
+
+        (type, data) = self.recvMsg()
+        assert type == 2
+        assert data.startswith(b'Cloanto')
+
+
+    def sendClose(self):
+        print('sendClose')
+
+        self.sendMsg(0x6d, b'')
+
+        (type, data) = self.recvMsg()
+        assert type == 0x0a
+        if data != b'\0\0\0\0\0':
+            print('sendClose: data == ' + binascii.hexlify(data))
+        # Format of data returned:
+        # Byte 0: ?
+        # Byte 1: ?
+        # Byte 2: ?
+        # Byte 3: 00 - No error
+        #         06 - File no longer exists
+        #         1c - Timed out waiting for host to request next read block
+        # Byte 4: Path in case of error 06.
+        #         Empty (null-terminated) otherwise?
+        #         Null-terminated string.
+        #assert data == b'\0\0\0\0\0'