Add dns feature

README.md

@@ -132,6 +132,64 @@ wait4x tcp 127.0.0.1:9090
 ```
 This command waits until the TCP port `9090` on `127.0.0.1` is available.
 
+### DNS
+
+```shell
+# Check A records existence
+wait4x dns A wait4x.dev
+
+# Check A records with expected ips
+wait4x dns A wait4x.dev --expected-ip 172.67.154.180
+
+# Check A records by defined nameserver
+wait4x dns A wait4x.dev --expected-ip 172.67.154.180 -n gordon.ns.cloudflare.com
+
+# Check AAAA records existence
+wait4x dns AAAA wait4x.dev
+
+# Check AAAA records with expected ips
+wait4x dns AAAA wait4x.dev --expected-ip '2606:4700:3033::ac43:9ab4'
+
+# Check AAAA records by defined nameserver
+wait4x dns AAAA wait4x.dev --expected-ip '2606:4700:3033::ac43:9ab4' -n gordon.ns.cloudflare.com
+
+# Check CNAME record existence
+wait4x dns CNAME 172.67.154.180
+
+# Check CNAME records with expected ips
+wait4x dns CNAME 172.67.154.180 --expected-domain wait4x.dev
+
+# Check CNAME record by defined nameserver
+wait4x dns CNAME 172.67.154.180 --expected-domain wait4x.dev -n gordon.ns.cloudflare.com
+
+# Check MX records existence
+wait4x dns MX wait4x.dev
+
+# Check MX records with expected domains
+wait4x dns MX wait4x.dev --expected-domain 'route1.mx.cloudflare.net'
+
+# Check MX records by defined nameserver
+wait4x dns MX wait4x.dev --expected-domain 'route1.mx.cloudflare.net.' -n gordon.ns.cloudflare.com
+
+# Check NS records existence
+wait4x dns NS wait4x.dev
+
+# Check NS records with expected nameservers
+wait4x dns NS wait4x.dev --expected-nameserver 'emma.ns.cloudflare.com'
+
+# Check NS records by defined nameserver
+wait4x dns NS wait4x.dev --expected-nameserver 'emma.ns.cloudflare.com' -n gordon.ns.cloudflare.com
+
+# Check TXT records existence
+wait4x dns TXT wait4x.dev
+
+# Check TXT records with expected values
+wait4x dns TXT wait4x.dev --expected-value 'include:_spf.mx.cloudflare.net'
+
+# Check TXT records by defined nameserver
+wait4x dns TXT wait4x.dev --expected-value 'include:_spf.mx.cloudflare.net' -n gordon.ns.cloudflare.com
+```
+
 ### HTTP
 
 Check HTTP connection and expect a specific status code:
@@ -361,4 +419,4 @@ distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
-```
+```

checker/dns/a/a.go

@@ -0,0 +1,101 @@
+// Copyright 2023 The Wait4X Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package a
+
+import (
+	"context"
+	"net"
+
+	"wait4x.dev/v2/checker"
+)
+
+// Option configures an DNS A records
+type Option func(d *A)
+
+// A represents DNS A data structure
+type A struct {
+	nameserver  string
+	address     string
+	expectedIPs []string
+	resolver    *net.Resolver
+}
+
+// New creates the DNS A checker
+func New(address string, opts ...Option) checker.Checker {
+	d := &A{
+		address:  address,
+		resolver: net.DefaultResolver,
+	}
+
+	// apply the list of options to A
+	for _, opt := range opts {
+		opt(d)
+	}
+
+	// Nameserver settings.
+	if d.nameserver != "" {
+		d.resolver = &net.Resolver{
+			Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
+				dialer := net.Dialer{}
+				return dialer.DialContext(ctx, network, d.nameserver)
+			},
+		}
+	}
+
+	return d
+}
+
+// WithNameServer overrides the default nameserver
+func WithNameServer(nameserver string) Option {
+	return func(d *A) {
+		d.nameserver = nameserver
+	}
+}
+
+// WithExpectedIPV4s sets expected IPv4s
+func WithExpectedIPV4s(ips []string) Option {
+	return func(d *A) {
+		d.expectedIPs = ips
+	}
+}
+
+// Identity returns the identity of the checker
+func (d *A) Identity() (string, error) {
+	return d.address, nil
+}
+
+// Check checks A DNS records
+func (d *A) Check(ctx context.Context) (err error) {
+	ips, err := d.resolver.LookupIP(ctx, "ip4", d.address)
+	if err != nil {
+		return err
+	}
+
+	for _, ip := range ips {
+		if len(d.expectedIPs) == 0 {
+			return nil
+		}
+		for _, expectedIP := range d.expectedIPs {
+			if expectedIP == ip.String() {
+				return nil
+			}
+		}
+	}
+
+	return checker.NewExpectedError(
+		"the A record value doesn't expect", nil,
+		"actual", ips, "expect", d.expectedIPs,
+	)
+}

checker/dns/a/a_test.go

@@ -0,0 +1,32 @@
+package a
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"wait4x.dev/v2/checker"
+)
+
+const server = "wait4x.dev"
+
+func TestCheckExistenceA(t *testing.T) {
+	d := New(server)
+	assert.Nil(t, d.Check(context.Background()))
+}
+
+func TestCorrectA(t *testing.T) {
+	d := New(server, WithExpectedIPV4s([]string{"172.67.154.180", "127.0.0.1"}))
+	assert.Nil(t, d.Check(context.Background()))
+}
+
+func TestIncorrectA(t *testing.T) {
+	var expectedError *checker.ExpectedError
+	d := New(server, WithExpectedIPV4s([]string{"127.0.0.1"}))
+	assert.ErrorAs(t, d.Check(context.Background()), &expectedError)
+}
+
+func TestCustomNSCorrectA(t *testing.T) {
+	d := New(server, WithNameServer("8.8.8.8:53"), WithExpectedIPV4s([]string{"172.67.154.180"}))
+	assert.Nil(t, d.Check(context.Background()))
+}

checker/dns/aaaa/aaaa.go

@@ -0,0 +1,101 @@
+// Copyright 2023 The Wait4X Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package aaaa
+
+import (
+	"context"
+	"net"
+
+	"wait4x.dev/v2/checker"
+)
+
+// Option configures an DNS AAAA records
+type Option func(d *AAAA)
+
+// AAAA represents DNS AAAA data structure
+type AAAA struct {
+	nameserver  string
+	address     string
+	expectedIPs []string
+	resolver    *net.Resolver
+}
+
+// New creates the DNS AAAA checker
+func New(address string, opts ...Option) checker.Checker {
+	d := &AAAA{
+		address:  address,
+		resolver: net.DefaultResolver,
+	}
+
+	// apply the list of options to AAAA
+	for _, opt := range opts {
+		opt(d)
+	}
+
+	// Nameserver settings.
+	if d.nameserver != "" {
+		d.resolver = &net.Resolver{
+			Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
+				dialer := net.Dialer{}
+				return dialer.DialContext(ctx, network, d.nameserver)
+			},
+		}
+	}
+
+	return d
+}
+
+// WithNameServer overrides the default nameserver
+func WithNameServer(nameserver string) Option {
+	return func(d *AAAA) {
+		d.nameserver = nameserver
+	}
+}
+
+// WithExpectedIPV6s sets expected IPv6s
+func WithExpectedIPV6s(ips []string) Option {
+	return func(d *AAAA) {
+		d.expectedIPs = ips
+	}
+}
+
+// Identity returns the identity of the checker
+func (d *AAAA) Identity() (string, error) {
+	return d.address, nil
+}
+
+// Check checks DNS records
+func (d *AAAA) Check(ctx context.Context) (err error) {
+	values, err := d.resolver.LookupIP(ctx, "ip6", d.address)
+	if err != nil {
+		return err
+	}
+
+	for _, ip := range values {
+		if len(d.expectedIPs) == 0 {
+			return nil
+		}
+		for _, expectedIP := range d.expectedIPs {
+			if expectedIP == ip.String() {
+				return nil
+			}
+		}
+	}
+
+	return checker.NewExpectedError(
+		"the AAAA record value doesn't expect", nil,
+		"actual", values, "expect", d.expectedIPs,
+	)
+}

checker/dns/aaaa/aaaa_test.go

@@ -0,0 +1,32 @@
+package aaaa
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"wait4x.dev/v2/checker"
+)
+
+const server = "wait4x.dev"
+
+func TestCheckExistenceAAAA(t *testing.T) {
+	d := New(server)
+	assert.Nil(t, d.Check(context.Background()))
+}
+
+func TestCorrectAAAA(t *testing.T) {
+	d := New(server, WithExpectedIPV6s([]string{"2606:4700:3034::6815:591"}))
+	assert.Nil(t, d.Check(context.Background()))
+}
+
+func TestIncorrectAAAA(t *testing.T) {
+	var expectedError *checker.ExpectedError
+	d := New(server, WithExpectedIPV6s([]string{"127.0.0.1"}))
+	assert.ErrorAs(t, d.Check(context.Background()), &expectedError)
+}
+
+func TestCustomNSCorrectAAAA(t *testing.T) {
+	d := New(server, WithNameServer("8.8.8.8:53"), WithExpectedIPV6s([]string{"2606:4700:3034::6815:591"}))
+	assert.Nil(t, d.Check(context.Background()))
+}