diff options
Diffstat (limited to 'internal/state/single.go')
| -rw-r--r-- | internal/state/single.go | 35 |
1 files changed, 16 insertions, 19 deletions
diff --git a/internal/state/single.go b/internal/state/single.go index 2c6bb4b..6817531 100644 --- a/internal/state/single.go +++ b/internal/state/single.go @@ -155,7 +155,6 @@ func (sm *StateManagerSingle) chooseTree(ctx context.Context, proposedTreeHead * log.Error("secondary is ahead of us: %d > %d", secSTH.TreeSize, proposedTreeHead.TreeSize) return refreshTreeHead(sm.signedTreeHead.TreeHead) } - if secSTH.TreeSize == proposedTreeHead.TreeSize { if secSTH.RootHash != proposedTreeHead.RootHash { log.Error("secondary root hash doesn't match our root hash at tree size %d", secSTH.TreeSize) @@ -164,27 +163,26 @@ func (sm *StateManagerSingle) chooseTree(ctx context.Context, proposedTreeHead * log.Debug("secondary is up-to-date with matching tree head, using proposed tree, size %d", proposedTreeHead.TreeSize) return proposedTreeHead } - // - // Now we know that the proposed tree size is larger than the secondary's tree size. - // We also now that the secondary's minimum tree size is 0. - // This means that the proposed tree size is at least 1. - // - // Case 1: secondary tree size is 0, primary tree size is >0 --> return based on what we signed before - // Case 2: secondary tree size is 1, primary tree size is >1 --> fetch consistency proof, if ok -> - // 2a) secondary tree size is smaller than or equal to what we than signed before -> return whatever we signed before - // 2b) secondary tree size is larger than what we signed before -> return secondary tree head - // - // (If not ok in case 2, return based on what we signed before) - // + // We now know that + // * the proposed tree is ahead of the secondary (including them not being equal) + // * the minimal tree size is 0, so the proposed tree is at tree size 1 or greater + + // Consistency proofs can not be produced from a tree of size 0, so don't try when the secondary is at 0. if secSTH.TreeSize == 0 { + log.Debug("secondary tree size is zero, using latest published tree head: size %d", sm.signedTreeHead.TreeSize) return refreshTreeHead(sm.signedTreeHead.TreeHead) } - if err := sm.verifyConsistencyWithLatest(ctx, secSTH.TreeHead); err != nil { - log.Error("secondaries tree not consistent with ours: %v", err) + if err := sm.verifyConsistency(ctx, &secSTH.TreeHead, proposedTreeHead); err != nil { + log.Error("secondary tree not consistent with ours: %v", err) return refreshTreeHead(sm.signedTreeHead.TreeHead) } - if secSTH.TreeSize <= sm.signedTreeHead.TreeSize { - log.Warning("secondary is behind what primary already signed: %d <= %d", secSTH.TreeSize, sm.signedTreeHead.TreeSize) + // We now know that + // * we have two candidates: latest published and secondary's tree + // * secondary's tree is verified to be consistent with our proposed tree + + // Protect against going backwards by chosing the larger of secondary tree and latest published. + if sm.signedTreeHead.TreeSize > secSTH.TreeHead.TreeSize { + log.Debug("using latest published tree head: size %d", sm.signedTreeHead.TreeSize) return refreshTreeHead(sm.signedTreeHead.TreeHead) } @@ -192,8 +190,7 @@ func (sm *StateManagerSingle) chooseTree(ctx context.Context, proposedTreeHead * return refreshTreeHead(secSTH.TreeHead) } -func (sm *StateManagerSingle) verifyConsistencyWithLatest(ctx context.Context, to types.TreeHead) error { - from := sm.signedTreeHead.TreeHead +func (sm *StateManagerSingle) verifyConsistency(ctx context.Context, from, to *types.TreeHead) error { req := &requests.ConsistencyProof{ OldSize: from.TreeSize, NewSize: to.TreeSize, |