106 lines
2.8 KiB
Go
106 lines
2.8 KiB
Go
// Package errors implements an HTTP error handling middleware.
|
|
package errors
|
|
|
|
import (
|
|
"fmt"
|
|
"log"
|
|
"runtime"
|
|
"strings"
|
|
"time"
|
|
|
|
"github.com/miekg/coredns/middleware"
|
|
|
|
"github.com/miekg/dns"
|
|
"golang.org/x/net/context"
|
|
)
|
|
|
|
// ErrorHandler handles DNS errors (and errors from other middleware).
|
|
type ErrorHandler struct {
|
|
Next middleware.Handler
|
|
LogFile string
|
|
Log *log.Logger
|
|
LogRoller *middleware.LogRoller
|
|
Debug bool // if true, errors are written out to client rather than to a log
|
|
}
|
|
|
|
func (h ErrorHandler) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
|
|
defer h.recovery(ctx, w, r)
|
|
|
|
rcode, err := h.Next.ServeDNS(ctx, w, r)
|
|
|
|
if err != nil {
|
|
state := middleware.State{W: w, Req: r}
|
|
errMsg := fmt.Sprintf("%s [ERROR %d %s %s] %v", time.Now().Format(timeFormat), rcode, state.Name(), state.Type(), err)
|
|
|
|
if h.Debug {
|
|
// Write error to response as a txt message instead of to log
|
|
answer := debugMsg(rcode, r)
|
|
txt, _ := dns.NewRR(". IN 0 TXT " + errMsg)
|
|
answer.Answer = append(answer.Answer, txt)
|
|
state.SizeAndDo(answer)
|
|
w.WriteMsg(answer)
|
|
return 0, err
|
|
}
|
|
h.Log.Println(errMsg)
|
|
}
|
|
|
|
return rcode, err
|
|
}
|
|
|
|
func (h ErrorHandler) recovery(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) {
|
|
rec := recover()
|
|
if rec == nil {
|
|
return
|
|
}
|
|
|
|
state := middleware.State{W: w, Req: r}
|
|
// Obtain source of panic
|
|
// From: https://gist.github.com/swdunlop/9629168
|
|
var name, file string // function name, file name
|
|
var line int
|
|
var pc [16]uintptr
|
|
n := runtime.Callers(3, pc[:])
|
|
for _, pc := range pc[:n] {
|
|
fn := runtime.FuncForPC(pc)
|
|
if fn == nil {
|
|
continue
|
|
}
|
|
file, line = fn.FileLine(pc)
|
|
name = fn.Name()
|
|
if !strings.HasPrefix(name, "runtime.") {
|
|
break
|
|
}
|
|
}
|
|
|
|
// Trim file path
|
|
delim := "/coredns/"
|
|
pkgPathPos := strings.Index(file, delim)
|
|
if pkgPathPos > -1 && len(file) > pkgPathPos+len(delim) {
|
|
file = file[pkgPathPos+len(delim):]
|
|
}
|
|
|
|
panicMsg := fmt.Sprintf("%s [PANIC %s %s] %s:%d - %v", time.Now().Format(timeFormat), r.Question[0].Name, dns.Type(r.Question[0].Qtype), file, line, rec)
|
|
if h.Debug {
|
|
// Write error and stack trace to the response rather than to a log
|
|
var stackBuf [4096]byte
|
|
stack := stackBuf[:runtime.Stack(stackBuf[:], false)]
|
|
answer := debugMsg(dns.RcodeServerFailure, r)
|
|
// add stack buf in TXT, limited to 255 chars for now.
|
|
txt, _ := dns.NewRR(". IN 0 TXT " + string(stack[:255]))
|
|
answer.Answer = append(answer.Answer, txt)
|
|
state.SizeAndDo(answer)
|
|
w.WriteMsg(answer)
|
|
} else {
|
|
// Currently we don't use the function name, since file:line is more conventional
|
|
h.Log.Printf(panicMsg)
|
|
}
|
|
}
|
|
|
|
// debugMsg creates a debug message that gets send back to the client.
|
|
func debugMsg(rcode int, r *dns.Msg) *dns.Msg {
|
|
answer := new(dns.Msg)
|
|
answer.SetRcode(r, rcode)
|
|
return answer
|
|
}
|
|
|
|
const timeFormat = "02/Jan/2006:15:04:05 -0700"
|