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@@ -289,6 +289,7 @@ see tor-design.pdf.
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6 -- CREATED_FAST (Circuit created, no PK) (See Sec 5.1)
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7 -- VERSIONS (Negotiate proto version) (See Sec 4)
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8 -- NETINFO (Time and address info) (See Sec 4)
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+ 9 -- RELAY_EARLY (End-to-end data; limited) (See sec 5.6)
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The interpretation of 'Payload' depends on the type of the cell.
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PADDING: Payload is unused.
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@@ -623,9 +624,9 @@ see tor-design.pdf.
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5.5. Routing relay cells
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- When an OR receives a RELAY cell, it checks the cell's circID and
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- determines whether it has a corresponding circuit along that
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- connection. If not, the OR drops the RELAY cell.
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+ When an OR receives a RELAY or RELAY_EARLY cell, it checks the cell's
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+ circID and determines whether it has a corresponding circuit along that
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+ connection. If not, the OR drops the cell.
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Otherwise, if the OR is not at the OP edge of the circuit (that is,
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either an 'exit node' or a non-edge node), it de/encrypts the payload
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@@ -653,6 +654,24 @@ see tor-design.pdf.
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For more information, see section 6 below.
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+5.6. Handling relay_early cells
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+
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+ A RELAY_EARLY cell is designed to limit the length any circuit can reach.
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+ When an OR receives a RELAY_EARLY cell, and the next node in the circuit
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+ is speaking v2 of the link protocol or later, the OR relays the cell as a
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+ RELAY_EARLY cell. Otherwise, it relays it as a RELAY cell.
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+
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+ If a node ever receives more than 8 RELAY_EARLY cells on a given circuit,
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+ it SHOULD close the circuit.
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+
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+ When speaking v2 of the link protocol or later, clients MUST only send
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+ EXTEND cells inside RELAY_EARLY cells. Clients SHOULD send the first ~8
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+ RELAY cells that are not targeted at the first hop of any circuit as
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+ RELAY_EARLY cells too, in order to partially conceal the circuit length.
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+
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+ [In a future version of Tor, servers will reject any EXTEND cell not
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+ received in a RELAY_EARLY cell. See proposal 110.]
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+
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6. Application connections and stream management
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6.1. Relay cells
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