mirror of
https://github.com/yarrick/iodine.git
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99 lines
2.3 KiB
Plaintext
99 lines
2.3 KiB
Plaintext
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Detailed specification of protocol in version 00000403
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======================================================
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This protocol varies a lot from earlier ones and will
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hopefully give cleaner code and enable more features.
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Common header:
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7654 3210
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+----+----+
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|CCCC|UUUU|
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+----+----+
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CCCC = Command
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UUUU = User id
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Commands:
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0: Version
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1: Login
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2: Case check
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3: Codec switch
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4: Data
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5: Ping
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6: -
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7: -
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8: -
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9: -
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A: -Reserved- (So header byte will never encode to a v)
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B: -
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C: -
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D: -
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E: -
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F: -
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CMC = 2 byte Cache Miss Counter, increased every time it is used
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Version:
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Client sends:
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Command = 0x0, User = 0xF
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Data is 4 bytes big endian protocol version
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Ends with CMC
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Server replies:
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Command = 0x0, User = userid
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Then 4 chars, followed by big endian int:
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VACK (version ok), followed by login challenge
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VNAK (version differs), followed by server protocol version
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VFUL (server has no free slots), followed by max users
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Login:
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Command = 0x1, User = userid from version reply
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Client sends:
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16 bytes MD5 hash of: (first 32 bytes of password) xor (8 repetitions of login challenge)
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Ends with CMC
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Server replies:
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4 chars, then maybe three ints
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LACK serverip clientip mtu means login accepted
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LNAK means not accepted
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Case check:
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Command = 0x2, User = userid from version reply
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Client sends:
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Lots of data that should not be decoded
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Server replies:
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The requested domain copied raw
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Switch codec:
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Command = 0x03, User = userid
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Client sends:
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One byte, with value 5 or 6, representing number of bits per byte in encoding
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Server sends:
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Name of codec if accepted. After this all upstream packets must be encoded with the new codec.
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BADCODEC if not accepted. Client must then revert to Base64
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Data:
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Command = 0x04, User = userid
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Data header:
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76543210 7 6 543210
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+--------+-+-+------+
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|SSSSSSSS|L|C|FFFFFF|
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+--------+-+-+------+
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SSSSSSSS = Packet sequence number
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L = Last fragment in packet flag
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C = Compression used flag
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FFFFFF = Fragment index in packet
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The data header is used both by the server and the client, followed by a fragment.
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Packet and fragment numbers are used to detect retransmits by dns relay.
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When a fragment arrives with L bit set, the packet should be pushed to the tun device.
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If the C bit is set, it should be decompressed before sent to tun device.
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Ping:
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Command = 0x04, User = userid
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Client sends:
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Only a CMC
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Server replies:
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With a Data packet or 0 bytes.
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