dns.go

Documentation: github.com/letsencrypt/boulder/observer/probers/dns

     1  package probers
     2  
     3  import (
     4  	"fmt"
     5  	"time"
     6  
     7  	"github.com/miekg/dns"
     8  )
     9  
    10  // DNSProbe is the exported 'Prober' object for monitors configured to
    11  // perform DNS requests.
    12  type DNSProbe struct {
    13  	proto   string
    14  	server  string
    15  	recurse bool
    16  	qname   string
    17  	qtype   uint16
    18  }
    19  
    20  // Name returns a string that uniquely identifies the monitor.
    21  func (p DNSProbe) Name() string {
    22  	recursion := func() string {
    23  		if p.recurse {
    24  			return "recurse"
    25  		}
    26  		return "no-recurse"
    27  	}()
    28  	return fmt.Sprintf(
    29  		"%s-%s-%s-%s-%s", p.server, p.proto, recursion, dns.TypeToString[p.qtype], p.qname)
    30  }
    31  
    32  // Kind returns a name that uniquely identifies the `Kind` of `Prober`.
    33  func (p DNSProbe) Kind() string {
    34  	return "DNS"
    35  }
    36  
    37  // Probe performs the configured DNS query.
    38  func (p DNSProbe) Probe(timeout time.Duration) (bool, time.Duration) {
    39  	m := new(dns.Msg)
    40  	m.SetQuestion(dns.Fqdn(p.qname), p.qtype)
    41  	m.RecursionDesired = p.recurse
    42  	c := dns.Client{Timeout: timeout, Net: p.proto}
    43  	start := time.Now()
    44  	r, _, err := c.Exchange(m, p.server)
    45  	if err != nil {
    46  		return false, time.Since(start)
    47  	}
    48  	if r == nil {
    49  		return false, time.Since(start)
    50  	}
    51  	if r.Rcode != dns.RcodeSuccess {
    52  		return false, time.Since(start)
    53  	}
    54  	return true, time.Since(start)
    55  }
    56
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