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network: don't leak our exact time skew in handshakes.

This commit is contained in:
Henry de Valence 2020-09-01 11:30:08 -07:00
parent 1b5a824584
commit a5b6f39850
1 changed files with 22 additions and 2 deletions
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24
zebra-network/src/peer/handshake.rs
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@ -7,7 +7,7 @@ use std::{
task::{Context, Poll},
};
use chrono::Utc;
use chrono::{TimeZone, Utc};
use futures::{
channel::{mpsc, oneshot},
prelude::*,
@ -233,10 +233,30 @@ where
.expect("mutex should be unpoisoned")
.insert(local_nonce);
// Don't leak our exact clock skew to our peers. On the other hand,
// we can't deviate too much, or zcashd will get confused.
// Inspection of the zcashd source code reveals that the timestamp
// is only ever used at the end of parsing the version message, in
//
// pfrom->nTimeOffset = timeWarning.AddTimeData(pfrom->addr, nTime, GetTime());
//
// AddTimeData is defined in src/timedata.cpp and is a no-op as long
// as the difference between the specified timestamp and the
// zcashd's local time is less than TIMEDATA_WARNING_THRESHOLD, set
// to 10 * 60 seconds (10 minutes).
//
// nTimeOffset is peer metadata that is never used, except for
// statistics.
//
// To try to stay within the range where zcashd will ignore our clock skew,
// truncate the timestamp to the nearest 5 minutes.
let now = Utc::now().timestamp();
let timestamp = Utc.timestamp(now - now.rem_euclid(5 * 60), 0);
let version = Message::Version {
version: constants::CURRENT_VERSION,
services: our_services,
timestamp: Utc::now(),
timestamp,
address_recv: (PeerServices::NODE_NETWORK, addr),
address_from: (our_services, our_addr),
nonce: local_nonce,