telegraf/internal/internal.go

194 lines
4.7 KiB
Go

package internal
import (
"bufio"
"bytes"
"crypto/rand"
"crypto/tls"
"crypto/x509"
"errors"
"fmt"
"io/ioutil"
"log"
"os"
"os/exec"
"strings"
"time"
"unicode"
)
const alphanum string = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
var (
TimeoutErr = errors.New("Command timed out.")
NotImplementedError = errors.New("not implemented yet")
)
// Duration just wraps time.Duration
type Duration struct {
Duration time.Duration
}
// UnmarshalTOML parses the duration from the TOML config file
func (d *Duration) UnmarshalTOML(b []byte) error {
dur, err := time.ParseDuration(string(b[1 : len(b)-1]))
if err != nil {
return err
}
d.Duration = dur
return nil
}
// ReadLines reads contents from a file and splits them by new lines.
// A convenience wrapper to ReadLinesOffsetN(filename, 0, -1).
func ReadLines(filename string) ([]string, error) {
return ReadLinesOffsetN(filename, 0, -1)
}
// ReadLines reads contents from file and splits them by new line.
// The offset tells at which line number to start.
// The count determines the number of lines to read (starting from offset):
// n >= 0: at most n lines
// n < 0: whole file
func ReadLinesOffsetN(filename string, offset uint, n int) ([]string, error) {
f, err := os.Open(filename)
if err != nil {
return []string{""}, err
}
defer f.Close()
var ret []string
r := bufio.NewReader(f)
for i := 0; i < n+int(offset) || n < 0; i++ {
line, err := r.ReadString('\n')
if err != nil {
break
}
if i < int(offset) {
continue
}
ret = append(ret, strings.Trim(line, "\n"))
}
return ret, nil
}
// RandomString returns a random string of alpha-numeric characters
func RandomString(n int) string {
var bytes = make([]byte, n)
rand.Read(bytes)
for i, b := range bytes {
bytes[i] = alphanum[b%byte(len(alphanum))]
}
return string(bytes)
}
// GetTLSConfig gets a tls.Config object from the given certs, key, and CA files.
// you must give the full path to the files.
// If all files are blank and InsecureSkipVerify=false, returns a nil pointer.
func GetTLSConfig(
SSLCert, SSLKey, SSLCA string,
InsecureSkipVerify bool,
) (*tls.Config, error) {
if SSLCert == "" && SSLKey == "" && SSLCA == "" && !InsecureSkipVerify {
return nil, nil
}
t := &tls.Config{
InsecureSkipVerify: InsecureSkipVerify,
}
if SSLCA != "" {
caCert, err := ioutil.ReadFile(SSLCA)
if err != nil {
return nil, errors.New(fmt.Sprintf("Could not load TLS CA: %s",
err))
}
caCertPool := x509.NewCertPool()
caCertPool.AppendCertsFromPEM(caCert)
t.RootCAs = caCertPool
}
if SSLCert != "" && SSLKey != "" {
cert, err := tls.LoadX509KeyPair(SSLCert, SSLKey)
if err != nil {
return nil, errors.New(fmt.Sprintf(
"Could not load TLS client key/certificate: %s",
err))
}
t.Certificates = []tls.Certificate{cert}
t.BuildNameToCertificate()
}
// will be nil by default if nothing is provided
return t, nil
}
// SnakeCase converts the given string to snake case following the Golang format:
// acronyms are converted to lower-case and preceded by an underscore.
func SnakeCase(in string) string {
runes := []rune(in)
length := len(runes)
var out []rune
for i := 0; i < length; i++ {
if i > 0 && unicode.IsUpper(runes[i]) && ((i+1 < length && unicode.IsLower(runes[i+1])) || unicode.IsLower(runes[i-1])) {
out = append(out, '_')
}
out = append(out, unicode.ToLower(runes[i]))
}
return string(out)
}
// CombinedOutputTimeout runs the given command with the given timeout and
// returns the combined output of stdout and stderr.
// If the command times out, it attempts to kill the process.
func CombinedOutputTimeout(c *exec.Cmd, timeout time.Duration) ([]byte, error) {
var b bytes.Buffer
c.Stdout = &b
c.Stderr = &b
if err := c.Start(); err != nil {
return nil, err
}
err := WaitTimeout(c, timeout)
return b.Bytes(), err
}
// RunTimeout runs the given command with the given timeout.
// If the command times out, it attempts to kill the process.
func RunTimeout(c *exec.Cmd, timeout time.Duration) error {
if err := c.Start(); err != nil {
return err
}
return WaitTimeout(c, timeout)
}
// WaitTimeout waits for the given command to finish with a timeout.
// It assumes the command has already been started.
// If the command times out, it attempts to kill the process.
func WaitTimeout(c *exec.Cmd, timeout time.Duration) error {
timer := time.NewTimer(timeout)
done := make(chan error)
go func() { done <- c.Wait() }()
select {
case err := <-done:
timer.Stop()
return err
case <-timer.C:
if err := c.Process.Kill(); err != nil {
log.Printf("FATAL error killing process: %s", err)
return err
}
// wait for the command to return after killing it
<-done
return TimeoutErr
}
}