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Add control of recursion desired flag for DNS probes #859

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merged 2 commits into from
Jan 25, 2022
Merged

Add control of recursion desired flag for DNS probes #859

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Add control of recursion desired flag for DNS probes
dgl Jan 2, 2022
676b9ed
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dgl Jan 24, 2022
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2 changes: 2 additions & 0 deletions CONFIGURATION.md
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Original file line number Diff line number Diff line change
Expand Up @@ -189,6 +189,8 @@ query_name: <string>
[ query_type: <string> | default = "ANY" ]
[ query_class: <string> | default = "IN" ]

[ recursion_desired: <boolean> | default = true ]
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# List of valid response codes.
valid_rcodes:
[ - <string> ... | default = "NOERROR" ]
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6 changes: 4 additions & 2 deletions config/config.go
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Expand Up @@ -82,6 +82,7 @@ var (
// DefaultDNSProbe set default value for DNSProbe
DefaultDNSProbe = DNSProbe{
IPProtocolFallback: true,
RecursionDesired: true,
}
)

Expand Down Expand Up @@ -264,8 +265,9 @@ type DNSProbe struct {
TransportProtocol string `yaml:"transport_protocol,omitempty"`
QueryClass string `yaml:"query_class,omitempty"` // Defaults to IN.
QueryName string `yaml:"query_name,omitempty"`
QueryType string `yaml:"query_type,omitempty"` // Defaults to ANY.
ValidRcodes []string `yaml:"valid_rcodes,omitempty"` // Defaults to NOERROR.
QueryType string `yaml:"query_type,omitempty"` // Defaults to ANY.
RecursionDesired bool `yaml:"recursion_desired,omitempty"` // Defaults to true.
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ValidRcodes []string `yaml:"valid_rcodes,omitempty"` // Defaults to NOERROR.
ValidateAnswer DNSRRValidator `yaml:"validate_answer_rrs,omitempty"`
ValidateAuthority DNSRRValidator `yaml:"validate_authority_rrs,omitempty"`
ValidateAdditional DNSRRValidator `yaml:"validate_additional_rrs,omitempty"`
Expand Down
2 changes: 1 addition & 1 deletion prober/dns.go
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Expand Up @@ -250,7 +250,7 @@ func ProbeDNS(ctx context.Context, target string, module config.Module, registry

msg := new(dns.Msg)
msg.Id = dns.Id()
msg.RecursionDesired = true
msg.RecursionDesired = module.DNS.RecursionDesired
msg.Question = make([]dns.Question, 1)
msg.Question[0] = dns.Question{dns.Fqdn(module.DNS.QueryName), qt, qc}

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45 changes: 35 additions & 10 deletions prober/dns_test.go
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Expand Up @@ -69,16 +69,20 @@ func startDNSServer(protocol string, handler func(dns.ResponseWriter, *dns.Msg))
func recursiveDNSHandler(w dns.ResponseWriter, r *dns.Msg) {
m := new(dns.Msg)
m.SetReply(r)
answers := []string{
"example.com. 3600 IN A 127.0.0.1",
"example.com. 3600 IN A 127.0.0.2",
}
for _, rr := range answers {
a, err := dns.NewRR(rr)
if err != nil {
panic(err)
if !r.RecursionDesired {
m.Rcode = dns.RcodeRefused
} else {
answers := []string{
"example.com. 3600 IN A 127.0.0.1",
"example.com. 3600 IN A 127.0.0.2",
}
for _, rr := range answers {
a, err := dns.NewRR(rr)
if err != nil {
panic(err)
}
m.Answer = append(m.Answer, a)
}
m.Answer = append(m.Answer, a)
}
if err := w.WriteMsg(m); err != nil {
panic(err)
Expand All @@ -99,13 +103,15 @@ func TestRecursiveDNSResponse(t *testing.T) {
IPProtocol: "ip4",
IPProtocolFallback: true,
QueryName: "example.com",
RecursionDesired: true,
}, true,
},
{
config.DNSProbe{
IPProtocol: "ip4",
IPProtocolFallback: true,
QueryName: "example.com",
RecursionDesired: true,
ValidRcodes: []string{"SERVFAIL", "NXDOMAIN"},
}, false,
},
Expand All @@ -114,6 +120,7 @@ func TestRecursiveDNSResponse(t *testing.T) {
IPProtocol: "ip4",
IPProtocolFallback: true,
QueryName: "example.com",
RecursionDesired: true,
ValidateAnswer: config.DNSRRValidator{
FailIfMatchesRegexp: []string{".*7200.*"},
FailIfNotMatchesRegexp: []string{".*3600.*"},
Expand All @@ -125,6 +132,7 @@ func TestRecursiveDNSResponse(t *testing.T) {
IPProtocol: "ip4",
IPProtocolFallback: true,
QueryName: "example.com",
RecursionDesired: true,
ValidateAuthority: config.DNSRRValidator{
FailIfMatchesRegexp: []string{".*7200.*"},
},
Expand All @@ -135,11 +143,20 @@ func TestRecursiveDNSResponse(t *testing.T) {
IPProtocol: "ip4",
IPProtocolFallback: true,
QueryName: "example.com",
RecursionDesired: true,
ValidateAdditional: config.DNSRRValidator{
FailIfNotMatchesRegexp: []string{".*3600.*"},
},
}, false,
},
{
config.DNSProbe{
IPProtocol: "ip4",
IPProtocolFallback: true,
QueryName: "example.com",
RecursionDesired: false,
}, false,
},
}

for _, protocol := range PROTOCOLS {
Expand All @@ -166,6 +183,9 @@ func TestRecursiveDNSResponse(t *testing.T) {
"probe_dns_authority_rrs": 0,
"probe_dns_additional_rrs": 0,
}
if !test.Probe.RecursionDesired {
expectedResults["probe_dns_answer_rrs"] = 0
}
checkRegistryResults(expectedResults, mfs, t)
}
}
Expand Down Expand Up @@ -474,6 +494,7 @@ func TestDNSProtocol(t *testing.T) {
QueryName: "example.com",
TransportProtocol: protocol,
IPProtocol: "ip6",
RecursionDesired: true,
},
}
registry := prometheus.NewRegistry()
Expand All @@ -497,6 +518,7 @@ func TestDNSProtocol(t *testing.T) {
Timeout: time.Second,
DNS: config.DNSProbe{
QueryName: "example.com",
RecursionDesired: true,
TransportProtocol: protocol,
IPProtocol: "ip4",
},
Expand All @@ -523,6 +545,7 @@ func TestDNSProtocol(t *testing.T) {
Timeout: time.Second,
DNS: config.DNSProbe{
QueryName: "example.com",
RecursionDesired: true,
TransportProtocol: protocol,
},
}
Expand All @@ -547,7 +570,8 @@ func TestDNSProtocol(t *testing.T) {
module = config.Module{
Timeout: time.Second,
DNS: config.DNSProbe{
QueryName: "example.com",
QueryName: "example.com",
RecursionDesired: true,
},
}
registry = prometheus.NewRegistry()
Expand Down Expand Up @@ -590,6 +614,7 @@ func TestDNSMetrics(t *testing.T) {
IPProtocol: "ip4",
IPProtocolFallback: true,
QueryName: "example.com",
RecursionDesired: true,
},
}
registry := prometheus.NewRegistry()
Expand Down
2 changes: 1 addition & 1 deletion prober/utils_test.go
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Expand Up @@ -162,7 +162,7 @@ func TestChooseProtocol(t *testing.T) {
registry = prometheus.NewPedanticRegistry()

ip, _, err = chooseProtocol(ctx, "ip4", false, "ipv6.google.com", registry, logger)
if err != nil && err.Error() != "address ipv6.google.com: no suitable address found" {
if err != nil && err.Error() != "address ipv6.google.com: no suitable address found" && err.Error() != "lookup ipv6.google.com: no such host" {
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t.Error(err)
} else if err == nil {
t.Error("should set error")
Expand Down