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p2p: Explain getdata msg incrementing ban score. #2632

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Merged
jrick merged 1 commit into from
Apr 22, 2026
+17 −5
Merged

p2p: Explain getdata msg incrementing ban score. #2632

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22 changes: 17 additions & 5 deletions p2p/peering.go
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
// Copyright (c) 2018-2025 The Decred developers
// Copyright (c) 2018-2026 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.

Expand Down Expand Up @@ -1300,12 +1300,24 @@ func (rp *RemotePeer) receivedMixMsg(ctx context.Context, msg mixing.Message) {
}

func (rp *RemotePeer) receivedGetData(ctx context.Context, msg *wire.MsgGetData) {
if rp.banScore.Increase(0, uint32(len(msg.InvList))*banThreshold/wire.MaxInvPerMsg) > banThreshold {
// A decaying ban score increase is applied to prevent exhausting resources
// with unusually large inventory queries.
//
// Requesting more than the maximum inventory vector length within a short
// period of time yields a score above the default ban threshold. Sustained
// bursts of small requests are not penalized as that would potentially ban
// peers performing the inintial chain sync.
//
// This incremental score decays each minute to half of its value.
delta := uint32(len(msg.InvList) * banThreshold / wire.MaxInvPerMsg)
newBanScore := rp.banScore.Increase(0, delta)
if newBanScore > banThreshold {
log.Warnf("%v: ban score reached threshold", rp.RemoteAddr())
rp.Disconnect(errors.E(errors.Protocol, "ban score reached"))
return
}

// Ignore if the user is not interested in getdata messages.
if rp.lp.messageIsMasked(MaskGetData) {
rp.lp.receivedGetData <- newInMsg(rp, msg)
}
Expand Down Expand Up @@ -2142,8 +2154,8 @@ func (rp *RemotePeer) sendMessageAck(ctx context.Context, msg wire.Message) erro
func (rp *RemotePeer) ReceivedOrphanHeader() error {
// Allow up to 10 orphan header chain announcements.
delta := uint32(banThreshold / 10)
bs := rp.banScore.Increase(0, delta)
if bs > banThreshold {
newBanScore := rp.banScore.Increase(0, delta)
if newBanScore > banThreshold {
return errors.E(errors.Protocol, "ban score reached due to orphan header")
}
return nil
Expand Down Expand Up @@ -2223,7 +2235,7 @@ func (rp *RemotePeer) receivedInv(ctx context.Context, inv *wire.MsgInv) {
return
}

// Ignore if the user is not interested in invs.
// Ignore if the user is not interested in inv messages.
if !rp.lp.messageIsMasked(MaskInv) {
return
}
Expand Down
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