mirror of
https://github.com/tailscale/tailscale.git
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120 lines
2.8 KiB
Go
120 lines
2.8 KiB
Go
// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package ipn
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import (
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"encoding/json"
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"errors"
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"io/ioutil"
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"os"
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"sync"
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"tailscale.com/atomicfile"
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)
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// ErrStateNotExist is returned by StateStore.ReadState when the
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// requested state ID doesn't exist.
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var ErrStateNotExist = errors.New("no state with given ID")
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// StateStore persists state, and produces it back on request.
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type StateStore interface {
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// ReadState returns the bytes associated with ID. Returns (nil,
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// ErrStateNotExist) if the ID doesn't have associated state.
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ReadState(id StateKey) ([]byte, error)
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// WriteState saves bs as the state associated with ID.
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WriteState(id StateKey, bs []byte) error
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}
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// MemoryStore is a store that keeps state in memory only.
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type MemoryStore struct {
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mu sync.Mutex
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cache map[StateKey][]byte
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}
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// ReadState implements the StateStore interface.
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func (s *MemoryStore) ReadState(id StateKey) ([]byte, error) {
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s.mu.Lock()
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defer s.mu.Unlock()
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if s.cache == nil {
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s.cache = map[StateKey][]byte{}
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}
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bs, ok := s.cache[id]
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if !ok {
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return nil, ErrStateNotExist
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}
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return bs, nil
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}
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// WriteState implements the StateStore interface.
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func (s *MemoryStore) WriteState(id StateKey, bs []byte) error {
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s.mu.Lock()
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defer s.mu.Unlock()
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if s.cache == nil {
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s.cache = map[StateKey][]byte{}
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}
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s.cache[id] = append([]byte(nil), bs...)
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return nil
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}
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// FileStore is a StateStore that uses a JSON file for persistence.
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type FileStore struct {
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path string
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mu sync.RWMutex
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cache map[StateKey][]byte
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}
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// NewFileStore returns a new file store that persists to path.
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func NewFileStore(path string) (*FileStore, error) {
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bs, err := ioutil.ReadFile(path)
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if err != nil {
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if os.IsNotExist(err) {
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// Write out an initial file, to verify that we can write
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// to the path.
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if err = atomicfile.WriteFile(path, []byte("{}"), 0600); err != nil {
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return nil, err
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}
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return &FileStore{
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path: path,
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cache: map[StateKey][]byte{},
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}, nil
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}
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return nil, err
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}
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ret := &FileStore{
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path: path,
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cache: map[StateKey][]byte{},
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}
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if err := json.Unmarshal(bs, &ret.cache); err != nil {
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return nil, err
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}
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return ret, nil
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}
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// ReadState implements the StateStore interface.
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func (s *FileStore) ReadState(id StateKey) ([]byte, error) {
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s.mu.RLock()
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defer s.mu.RUnlock()
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bs, ok := s.cache[id]
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if !ok {
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return nil, ErrStateNotExist
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}
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return bs, nil
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}
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// WriteState implements the StateStore interface.
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func (s *FileStore) WriteState(id StateKey, bs []byte) error {
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s.mu.Lock()
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defer s.mu.Unlock()
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s.cache[id] = append([]byte(nil), bs...)
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bs, err := json.MarshalIndent(s.cache, "", " ")
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if err != nil {
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return err
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}
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return atomicfile.WriteFile(s.path, bs, 0600)
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}
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