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https://github.com/SSLMate/certspotter.git
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4fbbc5818e
Instead of writing log errors to stderr, write them to a file in the state directory. When reporting a health check failure, include the path to the file and the last several lines. Log files are named by date, and the last 7 days are kept. Closes #106
118 lines
2.8 KiB
Go
118 lines
2.8 KiB
Go
// Copyright (C) 2017, 2023 Opsmate, Inc.
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//
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// This Source Code Form is subject to the terms of the Mozilla
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// Public License, v. 2.0. If a copy of the MPL was not distributed
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// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
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//
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// This software is distributed WITHOUT A WARRANTY OF ANY KIND.
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// See the Mozilla Public License for details.
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package monitor
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import (
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"crypto/rand"
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"encoding/hex"
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"encoding/json"
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"fmt"
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"io"
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"os"
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"slices"
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)
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func randomFileSuffix() string {
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var randomBytes [12]byte
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if _, err := rand.Read(randomBytes[:]); err != nil {
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panic(err)
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}
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return hex.EncodeToString(randomBytes[:])
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}
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func writeSyncFile(filename string, data []byte, perm os.FileMode) error {
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f, err := os.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, perm)
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if err != nil {
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return err
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}
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_, err = f.Write(data)
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if err2 := f.Sync(); err2 != nil && err == nil {
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err = err2
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}
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if err2 := f.Close(); err2 != nil && err == nil {
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err = err2
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}
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return err
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}
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func writeFile(filename string, data []byte, perm os.FileMode) error {
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tempname := filename + ".tmp." + randomFileSuffix()
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if err := writeSyncFile(tempname, data, perm); err != nil {
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return fmt.Errorf("error writing %s: %w", filename, err)
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}
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if err := os.Rename(tempname, filename); err != nil {
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os.Remove(tempname)
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return fmt.Errorf("error writing %s: %w", filename, err)
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}
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return nil
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}
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func writeTextFile(filename string, fileText string, perm os.FileMode) error {
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return writeFile(filename, []byte(fileText), perm)
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}
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func writeJSONFile(filename string, data any, perm os.FileMode) error {
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fileBytes, err := json.Marshal(data)
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if err != nil {
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return err
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}
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fileBytes = append(fileBytes, '\n')
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return writeFile(filename, fileBytes, perm)
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}
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func fileExists(filename string) bool {
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_, err := os.Lstat(filename)
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return err == nil
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}
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func tailFile(filename string, linesWanted int) ([]byte, int, error) {
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file, err := os.Open(filename)
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if err != nil {
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return nil, 0, err
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}
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defer file.Close()
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return tail(file, linesWanted, 4096)
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}
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func tail(r io.ReadSeeker, linesWanted int, chunkSize int) ([]byte, int, error) {
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var buf []byte
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linesGot := 0
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offset, err := r.Seek(0, io.SeekEnd)
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if err != nil {
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return nil, 0, err
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}
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for offset > 0 {
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readSize := chunkSize
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if offset < int64(readSize) {
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readSize = int(offset)
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}
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offset -= int64(readSize)
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if _, err := r.Seek(offset, io.SeekStart); err != nil {
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return nil, 0, err
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}
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buf = slices.Grow(buf, readSize)
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copy(buf[readSize:len(buf)+readSize], buf)
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buf = buf[:len(buf)+readSize]
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if _, err := io.ReadFull(r, buf[:readSize]); err != nil {
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return nil, 0, err
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}
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for i := readSize; i > 0; i-- {
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if buf[i-1] == '\n' {
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if linesGot == linesWanted {
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return buf[i:], linesGot, nil
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}
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linesGot++
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}
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}
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}
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return buf, linesGot, nil
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}
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