first code/readme/license commit

src/yggdrasil/signature.go

@@ -0,0 +1,58 @@
+package yggdrasil
+
+// This is where we record which signatures we've previously checked
+// It's so we can avoid needlessly checking them again
+
+import "sync"
+import "time"
+
+type sigManager struct {
+  mutex sync.RWMutex
+  checked map[sigBytes]knownSig
+  lastCleaned time.Time
+}
+
+type knownSig struct {
+  bs []byte
+  time time.Time
+}
+
+func (m *sigManager) init() {
+  m.checked = make(map[sigBytes]knownSig)
+}
+
+func (m *sigManager) check(key *sigPubKey, sig *sigBytes, bs []byte) bool {
+  if m.isChecked(sig, bs) { return true }
+  verified := verify(key, bs, sig)
+  if verified { m.putChecked(sig, bs) }
+  return verified
+}
+
+func (m *sigManager) isChecked(sig *sigBytes, bs []byte) bool {
+  m.mutex.RLock()
+  defer m.mutex.RUnlock()
+  k, isIn := m.checked[*sig]
+  if !isIn { return false }
+  if len(bs) != len(k.bs) { return false }
+  for idx := 0 ; idx < len(bs) ; idx++ {
+    if bs[idx] != k.bs[idx] { return false }
+  }
+  k.time = time.Now()
+  return true
+}
+
+func (m *sigManager) putChecked(newsig *sigBytes, bs []byte) {
+  m.mutex.Lock()
+  defer m.mutex.Unlock()
+  now := time.Now()
+  if time.Since(m.lastCleaned) > 60*time.Second {
+    // Since we have the write lock anyway, do some cleanup
+    for s, k := range m.checked {
+      if time.Since(k.time) > 60*time.Second { delete(m.checked, s) }
+    }
+    m.lastCleaned = now
+  }
+  k := knownSig{bs: bs, time: now}
+  m.checked[*newsig] = k
+}
+