Opened 9 months ago

Last modified 5 months ago

#29084 new defect

Ensure circuit padding RTT estimate handes var cells/wide creates

Reported by: asn Owned by:
Priority: Medium Milestone: Tor: unspecified
Component: Core Tor/Tor Version:
Severity: Normal Keywords: wtf-pad, tor-relay, tor-cell, padding
Cc: nickm Actual Points:
Parent ID: Points: 2
Reviewer: Sponsor: Sponsor2

Description (last modified by mikeperry)

The use_rtt_estimate field in the circuit padding machines lets machines offset the inter-packet delays by a middle-node estimated RTT value of packets that go from the middle to the exit/website.

We abort this measurement if we get two or more cells back-to-back in either direction, as this indicates that the half-duplex request/response circuit setup and RELAY_BEGIN sequence has finished.

However, if we switch to a multi-cell circuit handshake, then we will need to take that into account when measuring RTT.

If RELAY_EARLY is used only for the first cell of a multi-cell EXTEND2 payload,
then we can just count time between RELAY_EARLIES. But the proposal currently says MAY, but not MUST for this behavior.

Child Tickets

Change History (7)

comment:1 Changed 9 months ago by asn

Milestone: Tor: 0.4.0.x-finalTor: unspecified

comment:2 Changed 9 months ago by mikeperry

Keywords: 041-proposed added

comment:3 Changed 9 months ago by mikeperry

Points: 2

comment:4 Changed 9 months ago by nickm

Sponsor: Sponsor2

comment:5 Changed 8 months ago by mikeperry

Keywords: 041-proposed removed

Take some wtf-pad stuff out of 041-proposed

comment:6 Changed 5 months ago by mikeperry

Parent ID: #28632

comment:7 Changed 5 months ago by mikeperry

Description: modified (diff)
Summary: WTF-PAD: Test and improve circuit RTT measurementEnsure circuit padding RTT estimate handes var cells/wide creates
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