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