Peter Kurfer
49e58ac2e4
- move to Gitlab - make code better testable - create app abstraction for server - cleanup
101 lines
2.3 KiB
Go
101 lines
2.3 KiB
Go
package dns_mock
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import (
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"github.com/miekg/dns"
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"github.com/prometheus/client_golang/prometheus"
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"gitlab.com/inetmock/inetmock/pkg/logging"
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"go.uber.org/zap"
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)
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type regexHandler struct {
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handlerName string
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routes []resolverRule
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fallback ResolverFallback
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logger logging.Logger
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}
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func (rh *regexHandler) AddRule(rule resolverRule) {
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rh.routes = append(rh.routes, rule)
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}
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func (rh regexHandler) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
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timer := prometheus.NewTimer(requestDurationHistogram.WithLabelValues(rh.handlerName))
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defer func() {
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timer.ObserveDuration()
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}()
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m := new(dns.Msg)
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m.Compress = false
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m.SetReply(r)
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switch r.Opcode {
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case dns.OpcodeQuery:
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rh.handleQuery(m)
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}
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if err := w.WriteMsg(m); err != nil {
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rh.logger.Error(
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"Failed to write DNS response message",
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zap.Error(err),
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)
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}
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}
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func (rh regexHandler) handleQuery(m *dns.Msg) {
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for _, q := range m.Question {
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rh.logger.Info(
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"handling question",
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zap.String("question", q.Name),
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)
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switch q.Qtype {
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case dns.TypeA:
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totalHandledRequestsCounter.WithLabelValues(rh.handlerName).Inc()
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for _, rule := range rh.routes {
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if rule.pattern.MatchString(q.Name) {
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m.Authoritative = true
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answer := &dns.A{
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Hdr: dns.RR_Header{
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Name: q.Name,
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Rrtype: dns.TypeA,
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Class: dns.ClassINET,
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Ttl: 60,
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},
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A: rule.response,
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}
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m.Answer = append(m.Answer, answer)
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rh.logger.Info(
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"matched DNS rule",
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zap.String("pattern", rule.pattern.String()),
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zap.String("response", rule.response.String()),
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)
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return
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}
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}
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rh.handleFallbackForMessage(m, q)
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default:
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unhandledRequestsCounter.WithLabelValues(rh.handlerName).Inc()
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rh.logger.Warn(
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"Unhandled DNS question type - no response will be sent",
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zap.Uint16("question_type", q.Qtype),
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)
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}
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}
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}
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func (rh regexHandler) handleFallbackForMessage(m *dns.Msg, q dns.Question) {
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fallbackIP := rh.fallback.GetIP()
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answer := &dns.A{
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Hdr: dns.RR_Header{
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Name: q.Name,
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Rrtype: dns.TypeA,
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Class: dns.ClassINET,
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Ttl: 60,
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},
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A: fallbackIP,
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}
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rh.logger.Info(
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"Falling back to generated IP",
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zap.String("response", fallbackIP.String()),
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)
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m.Authoritative = true
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m.Answer = append(m.Answer, answer)
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}
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