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authorRasmus Dahlberg <rasmus.dahlberg@kau.se>2021-06-07 00:19:40 +0200
committerRasmus Dahlberg <rasmus.dahlberg@kau.se>2021-06-07 00:19:40 +0200
commit932d29fd08c8ff401e471b4f764537493ccbd483 (patch)
treee840a4c62db92e84201fe9ceaa0594d99176792c /pkg/state/state_manager.go
parentbdf7a53d61cf044e526cc9123ca296615f838288 (diff)
parent345fe658fa8a4306caa74f72a618e499343675c2 (diff)
Merge branch 'design' into main
Diffstat (limited to 'pkg/state/state_manager.go')
-rw-r--r--pkg/state/state_manager.go154
1 files changed, 154 insertions, 0 deletions
diff --git a/pkg/state/state_manager.go b/pkg/state/state_manager.go
new file mode 100644
index 0000000..dfa73f4
--- /dev/null
+++ b/pkg/state/state_manager.go
@@ -0,0 +1,154 @@
+package state
+
+import (
+ "context"
+ "crypto"
+ "fmt"
+ "reflect"
+ "sync"
+ "time"
+
+ "github.com/golang/glog"
+ "github.com/google/certificate-transparency-go/schedule"
+ "github.com/system-transparency/stfe/pkg/trillian"
+ "github.com/system-transparency/stfe/pkg/types"
+)
+
+// StateManager coordinates access to the log's tree heads and (co)signatures
+type StateManager interface {
+ Latest(context.Context) (*types.SignedTreeHead, error)
+ ToSign(context.Context) (*types.SignedTreeHead, error)
+ Cosigned(context.Context) (*types.SignedTreeHead, error)
+ AddCosignature(context.Context, *[types.VerificationKeySize]byte, *[types.SignatureSize]byte) error
+ Run(context.Context)
+}
+
+// StateManagerSingle implements the StateManager interface. It is assumed that
+// the log server is running on a single-instance machine. So, no coordination.
+type StateManagerSingle struct {
+ client trillian.Client
+ signer crypto.Signer
+ interval time.Duration
+ deadline time.Duration
+ sync.RWMutex
+
+ // cosigned is the current cosigned tree head that is being served
+ cosigned types.SignedTreeHead
+
+ // tosign is the current tree head that is being cosigned by witnesses
+ tosign types.SignedTreeHead
+
+ // cosignature keeps track of all cosignatures for the tosign tree head
+ cosignature map[[types.HashSize]byte]*types.SigIdent
+}
+
+func NewStateManagerSingle(client trillian.Client, signer crypto.Signer, interval, deadline time.Duration) (*StateManagerSingle, error) {
+ sm := &StateManagerSingle{
+ client: client,
+ signer: signer,
+ interval: interval,
+ deadline: deadline,
+ }
+
+ ctx, _ := context.WithTimeout(context.Background(), sm.deadline)
+ sth, err := sm.Latest(ctx)
+ if err != nil {
+ return nil, fmt.Errorf("Latest: %v", err)
+ }
+
+ sm.cosigned = *sth
+ sm.tosign = *sth
+ sm.cosignature = map[[types.HashSize]byte]*types.SigIdent{
+ *sth.SigIdent[0].KeyHash: sth.SigIdent[0], // log signature
+ }
+ return sm, nil
+}
+
+func (sm *StateManagerSingle) Run(ctx context.Context) {
+ schedule.Every(ctx, sm.interval, func(ctx context.Context) {
+ ictx, _ := context.WithTimeout(ctx, sm.deadline)
+ nextTreeHead, err := sm.Latest(ictx)
+ if err != nil {
+ glog.Warningf("rotate failed: Latest: %v", err)
+ return
+ }
+
+ sm.Lock()
+ defer sm.Unlock()
+ sm.rotate(nextTreeHead)
+ })
+}
+
+func (sm *StateManagerSingle) Latest(ctx context.Context) (*types.SignedTreeHead, error) {
+ th, err := sm.client.GetTreeHead(ctx)
+ if err != nil {
+ return nil, fmt.Errorf("LatestTreeHead: %v", err)
+ }
+ sth, err := th.Sign(sm.signer)
+ if err != nil {
+ return nil, fmt.Errorf("sign: %v", err)
+ }
+ return sth, nil
+}
+
+func (sm *StateManagerSingle) ToSign(_ context.Context) (*types.SignedTreeHead, error) {
+ sm.RLock()
+ defer sm.RUnlock()
+ return &sm.tosign, nil
+}
+
+func (sm *StateManagerSingle) Cosigned(_ context.Context) (*types.SignedTreeHead, error) {
+ sm.RLock()
+ defer sm.RUnlock()
+ return &sm.cosigned, nil
+}
+
+func (sm *StateManagerSingle) AddCosignature(_ context.Context, vk *[types.VerificationKeySize]byte, sig *[types.SignatureSize]byte) error {
+ sm.Lock()
+ defer sm.Unlock()
+
+ if err := sm.tosign.TreeHead.Verify(vk, sig); err != nil {
+ return fmt.Errorf("Verify: %v", err)
+ }
+ witness := types.Hash(vk[:])
+ if _, ok := sm.cosignature[*witness]; ok {
+ return fmt.Errorf("signature-signer pair is a duplicate")
+ }
+ sm.cosignature[*witness] = &types.SigIdent{
+ Signature: sig,
+ KeyHash: witness,
+ }
+
+ glog.V(3).Infof("accepted new cosignature from witness: %x", *witness)
+ return nil
+}
+
+// rotate rotates the log's cosigned and stable STH. The caller must aquire the
+// source's read-write lock if there are concurrent reads and/or writes.
+func (sm *StateManagerSingle) rotate(next *types.SignedTreeHead) {
+ if reflect.DeepEqual(sm.cosigned.TreeHead, sm.tosign.TreeHead) {
+ // cosigned and tosign are the same. So, we need to merge all
+ // cosignatures that we already had with the new collected ones.
+ for _, sigident := range sm.cosigned.SigIdent {
+ if _, ok := sm.cosignature[*sigident.KeyHash]; !ok {
+ sm.cosignature[*sigident.KeyHash] = sigident
+ }
+ }
+ glog.V(3).Infof("cosigned tree head repeated, merged signatures")
+ }
+ var cosignatures []*types.SigIdent
+ for _, sigident := range sm.cosignature {
+ cosignatures = append(cosignatures, sigident)
+ }
+
+ // Update cosigned tree head
+ sm.cosigned.TreeHead = sm.tosign.TreeHead
+ sm.cosigned.SigIdent = cosignatures
+
+ // Update to-sign tree head
+ sm.tosign = *next
+ sm.cosignature = map[[types.HashSize]byte]*types.SigIdent{
+ *next.SigIdent[0].KeyHash: next.SigIdent[0], // log signature
+ }
+ glog.V(3).Infof("rotated tree heads")
+}