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// Copyright 2019 Google LLC. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package submission
import (
"bytes"
"fmt"
"net/http"
"sync"
"time"
"github.com/google/certificate-transparency-go/loglist3"
"github.com/google/certificate-transparency-go/x509util"
)
const (
// HttpClientTimeout timeout for Log list reader http client.
httpClientTimeout = 10 * time.Second
)
// LogListData wraps info on external LogList, keeping its JSON source and time
// of download.
type LogListData struct {
JSON []byte
List *loglist3.LogList
DownloadTime time.Time
}
// LogListRefresher is interface for Log List updates watcher.
type LogListRefresher interface {
Refresh() (*LogListData, error)
LastJSON() []byte
Source() string
}
// logListRefresherImpl regularly reads Log-list and emits notifications when
// updates/errors observed. Implements LogListRefresher interface.
type logListRefresherImpl struct {
// updateMu limits LogListRefresherImpl to a single Refresh() at a time.
updateMu sync.RWMutex
lastJSON []byte
path string
client *http.Client
}
// NewCustomLogListRefresher creates and inits a LogListRefresherImpl instance.
func NewCustomLogListRefresher(client *http.Client, llPath string) LogListRefresher {
return &logListRefresherImpl{
path: llPath,
client: client,
}
}
// NewLogListRefresher creates and inits a LogListRefresherImpl instance using
// default http.Client
func NewLogListRefresher(llPath string) LogListRefresher {
return NewCustomLogListRefresher(&http.Client{Timeout: httpClientTimeout}, llPath)
}
// Refresh fetches the log list and returns its source, formed LogList and
// timestamp if source has changed compared to previous Refresh.
func (llr *logListRefresherImpl) Refresh() (*LogListData, error) {
llr.updateMu.Lock()
defer llr.updateMu.Unlock()
t := time.Now()
json, err := x509util.ReadFileOrURL(llr.path, llr.client)
if err != nil {
return nil, fmt.Errorf("failed to read %q: %v", llr.path, err)
}
if bytes.Equal(json, llr.lastJSON) {
return nil, nil
}
ll, err := loglist3.NewFromJSON(json)
if err != nil {
return nil, fmt.Errorf("failed to parse %q: %v", llr.path, err)
}
llr.lastJSON = json
return &LogListData{JSON: json, List: ll, DownloadTime: t}, nil
}
// LastJSON returns last version of Log list in JSON.
func (llr *logListRefresherImpl) LastJSON() []byte {
llr.updateMu.Lock()
defer llr.updateMu.Unlock()
if llr.lastJSON == nil {
return []byte{}
}
return llr.lastJSON
}
// Source exposes internal Log list path.
func (llr *logListRefresherImpl) Source() string {
return llr.path
}
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