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c4ab98c6e3
This checks if the next middleware to be called is nil, and if so returns ServerFailure and an error. This makes the next calling more robust and saves some lines of code. Also prefix the error with the name of the middleware to aid in debugging.
63 lines
1.6 KiB
Go
63 lines
1.6 KiB
Go
// Package chaos implements a middleware that answer to 'CH version.bind TXT' type queries.
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package chaos
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import (
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"os"
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"github.com/miekg/coredns/middleware"
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"github.com/miekg/coredns/request"
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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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// Chaos allows CoreDNS to reply to CH TXT queries and return author or
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// version information.
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type Chaos struct {
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Next middleware.Handler
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Version string
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Authors map[string]bool
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}
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// ServeDNS implements the middleware.Handler interface.
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func (c Chaos) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
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state := request.Request{W: w, Req: r}
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if state.QClass() != dns.ClassCHAOS || state.QType() != dns.TypeTXT {
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return middleware.NextOrFailure(c.Name(), c.Next, ctx, w, r)
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}
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m := new(dns.Msg)
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m.SetReply(r)
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hdr := dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeTXT, Class: dns.ClassCHAOS, Ttl: 0}
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switch state.Name() {
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default:
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return c.Next.ServeDNS(ctx, w, r)
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case "authors.bind.":
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for a := range c.Authors {
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m.Answer = append(m.Answer, &dns.TXT{Hdr: hdr, Txt: []string{trim(a)}})
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}
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case "version.bind.", "version.server.":
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m.Answer = []dns.RR{&dns.TXT{Hdr: hdr, Txt: []string{trim(c.Version)}}}
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case "hostname.bind.", "id.server.":
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hostname, err := os.Hostname()
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if err != nil {
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hostname = "localhost"
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}
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m.Answer = []dns.RR{&dns.TXT{Hdr: hdr, Txt: []string{trim(hostname)}}}
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}
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state.SizeAndDo(m)
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w.WriteMsg(m)
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return 0, nil
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}
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// Name implements the Handler interface.
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func (c Chaos) Name() string { return "chaos" }
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func trim(s string) string {
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if len(s) < 256 {
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return s
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}
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return s[:255]
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}
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