yggdrasil-go/src/yggdrasil/signature.go

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
}