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soypat
31 lines
1.6 KiB
Go
31 lines
1.6 KiB
Go
package tcp
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// TransmitUnlimited size returned by [Policy.PreTx] to signal no new data transmit limit (no congestion control).
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const TransmitUnlimited = ^Size(0)
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// Policy observes segment traffic and steers transmit behaviour: RTO,
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// congestion control and the like (discussion #157). The tcp package holds no
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// clock, so a Policy needing time carries its own (issue #140).
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// Introspection stays off the interface; put it on the concrete type.
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type Policy interface {
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// Reset returns the Policy to its pre-connection state. Called on every
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// (re)open and Abort. Must preserve configuration such as a clock.
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Reset()
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// PreTx is called before writing to a frame.
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// The outgoing frame options can be set by the Policy and will be respected if Frame offset >5.
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// rtxFrom is ignored unless within [snd.UNA, snd.NXT] and returned retransmit==true.
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// newTransmitLimit sets the maximum number of new bytes to send over the wire (congestion control).
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// If not implementing congestion control then newTransmitLimit=[TransmitUnlimited].
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PreTx(h *Handler, outgoingOpts Frame) (newTransmitLimit Size, rtxFrom Value, retransmit bool)
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// PostTx called on leaving the transmit path with the fully written frame.
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PostTx(h *Handler, outgoing Frame)
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// PreRx is called by [Handler] on every incoming segment.
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// PreRx can choose to drop segment if it returns keep=false.
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PreRx(h *Handler, incoming Frame) (keep bool)
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// PostRx is called by [Handler] after accepting an incoming segment.
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// TODO: congestion control will also want the pre-Recv snd.UNA here.
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PostRx(h *Handler, prevState State, accepted Frame)
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}
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