73 lines
1.2 KiB
Go
73 lines
1.2 KiB
Go
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package main
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import (
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"crypto/rand"
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"encoding/base64"
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"errors"
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"io"
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"sync"
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"time"
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"golang.org/x/net/context"
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)
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var (
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gcInterval = time.Minute
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expiresIn = time.Minute * 10
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)
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type memNonceSource struct {
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mu sync.Mutex
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nonces map[string]time.Time
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}
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func newNonceSource(ctx context.Context) *memNonceSource {
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s := &memNonceSource{nonces: make(map[string]time.Time)}
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go s.garbageCollect(ctx)
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return s
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}
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func (s *memNonceSource) Nonce() (string, error) {
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buff := make([]byte, 32)
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if _, err := io.ReadFull(rand.Reader, buff); err != nil {
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return "", err
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}
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nonce := base64.RawURLEncoding.EncodeToString(buff)
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s.mu.Lock()
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defer s.mu.Unlock()
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s.nonces[nonce] = time.Now().Add(expiresIn)
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return nonce, nil
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}
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func (s *memNonceSource) ClaimNonce(nonce string) error {
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s.mu.Lock()
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defer s.mu.Unlock()
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if _, ok := s.nonces[nonce]; ok {
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delete(s.nonces, nonce)
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return nil
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}
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return errors.New("invalid nonce")
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}
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func (s *memNonceSource) garbageCollect(ctx context.Context) {
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for {
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select {
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case <-ctx.Done():
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case <-time.After(gcInterval):
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s.mu.Lock()
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now := time.Now()
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for nonce, exp := range s.nonces {
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if now.After(exp) {
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delete(s.nonces, nonce)
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}
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}
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s.mu.Unlock()
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}
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}
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}
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