151 lines
4.4 KiB
Go
151 lines
4.4 KiB
Go
// Copyright 2023 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package light
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import (
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"errors"
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"sync"
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"time"
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"github.com/ethereum/go-ethereum/beacon/types"
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"github.com/ethereum/go-ethereum/log"
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)
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// HeadTracker keeps track of the latest validated head and the "prefetch" head
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// which is the (not necessarily validated) head announced by the majority of
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// servers.
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type HeadTracker struct {
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lock sync.RWMutex
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committeeChain *CommitteeChain
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minSignerCount int
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signedHead types.SignedHeader
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hasSignedHead bool
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finalityUpdate types.FinalityUpdate
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hasFinalityUpdate bool
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prefetchHead types.HeadInfo
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changeCounter uint64
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}
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// NewHeadTracker creates a new HeadTracker.
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func NewHeadTracker(committeeChain *CommitteeChain, minSignerCount int) *HeadTracker {
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return &HeadTracker{
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committeeChain: committeeChain,
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minSignerCount: minSignerCount,
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}
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}
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// ValidatedHead returns the latest validated head.
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func (h *HeadTracker) ValidatedHead() (types.SignedHeader, bool) {
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h.lock.RLock()
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defer h.lock.RUnlock()
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return h.signedHead, h.hasSignedHead
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}
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// ValidatedFinality returns the latest validated finality.
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func (h *HeadTracker) ValidatedFinality() (types.FinalityUpdate, bool) {
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h.lock.RLock()
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defer h.lock.RUnlock()
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return h.finalityUpdate, h.hasFinalityUpdate
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}
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// ValidateHead validates the given signed head. If the head is successfully validated
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// and it is better than the old validated head (higher slot or same slot and more
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// signers) then ValidatedHead is updated. The boolean return flag signals if
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// ValidatedHead has been changed.
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func (h *HeadTracker) ValidateHead(head types.SignedHeader) (bool, error) {
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h.lock.Lock()
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defer h.lock.Unlock()
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replace, err := h.validate(head, h.signedHead)
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if replace {
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h.signedHead, h.hasSignedHead = head, true
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h.changeCounter++
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}
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return replace, err
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}
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func (h *HeadTracker) ValidateFinality(update types.FinalityUpdate) (bool, error) {
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h.lock.Lock()
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defer h.lock.Unlock()
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replace, err := h.validate(update.SignedHeader(), h.finalityUpdate.SignedHeader())
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if replace {
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h.finalityUpdate, h.hasFinalityUpdate = update, true
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h.changeCounter++
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}
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return replace, err
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}
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func (h *HeadTracker) validate(head, oldHead types.SignedHeader) (bool, error) {
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signerCount := head.Signature.SignerCount()
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if signerCount < h.minSignerCount {
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return false, errors.New("low signer count")
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}
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if head.Header.Slot < oldHead.Header.Slot || (head.Header.Slot == oldHead.Header.Slot && signerCount <= oldHead.Signature.SignerCount()) {
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return false, nil
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}
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sigOk, age, err := h.committeeChain.VerifySignedHeader(head)
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if err != nil {
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return false, err
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}
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if age < 0 {
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log.Warn("Future signed head received", "age", age)
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}
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if age > time.Minute*2 {
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log.Warn("Old signed head received", "age", age)
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}
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if !sigOk {
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return false, errors.New("invalid header signature")
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}
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return true, nil
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}
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// PrefetchHead returns the latest known prefetch head's head info.
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// This head can be used to start fetching related data hoping that it will be
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// validated soon.
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// Note that the prefetch head cannot be validated cryptographically so it should
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// only be used as a performance optimization hint.
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func (h *HeadTracker) PrefetchHead() types.HeadInfo {
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h.lock.RLock()
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defer h.lock.RUnlock()
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return h.prefetchHead
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}
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// SetPrefetchHead sets the prefetch head info.
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// Note that HeadTracker does not verify the prefetch head, just acts as a thread
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// safe bulletin board.
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func (h *HeadTracker) SetPrefetchHead(head types.HeadInfo) {
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h.lock.Lock()
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defer h.lock.Unlock()
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if head == h.prefetchHead {
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return
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}
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h.prefetchHead = head
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h.changeCounter++
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}
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func (h *HeadTracker) ChangeCounter() uint64 {
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h.lock.RLock()
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defer h.lock.RUnlock()
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return h.changeCounter
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}
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