.gitea/workflows/check.yml

@@ -1,26 +0,0 @@
-name: Check
-
-on:
-  push:
-    branches: [main]
-  pull_request:
-    branches: [main]
-
-jobs:
-  check:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
-
-      - uses: actions/setup-go@40f1582b2485089dde7abd97c1529aa768e1baff # v5
-        with:
-          go-version-file: go.mod
-
-      - name: Install golangci-lint
-        run: go install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@5d1e709b7be35cb2025444e19de266b056b7b7ee # v2.10.1
-
-      - name: Install goimports
-        run: go install golang.org/x/tools/cmd/goimports@009367f5c17a8d4c45a961a3a509277190a9a6f0 # v0.42.0
-
-      - name: Run make check
-        run: make check

README.md

@@ -376,13 +376,6 @@ docker run -d \
 
 ---
 
-## Planned Future Features (Post-1.0)
-
-- **DNSSEC validation**: Validate the DNSSEC chain of trust during
-  iterative resolution and report DNSSEC failures as notifications.
-
----
-
 ## Project Structure
 
 Follows the conventions defined in `CONVENTIONS.md`, adapted from the

go.mod

@@ -7,24 +7,19 @@ require (
 	github.com/go-chi/chi/v5 v5.2.5
 	github.com/go-chi/cors v1.2.2
 	github.com/joho/godotenv v1.5.1
-	github.com/miekg/dns v1.1.72
 	github.com/prometheus/client_golang v1.23.2
 	github.com/spf13/viper v1.21.0
-	github.com/stretchr/testify v1.11.1
 	go.uber.org/fx v1.24.0
 	golang.org/x/net v0.50.0
-	golang.org/x/sync v0.19.0
 )
 
 require (
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
-	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/fsnotify/fsnotify v1.9.0 // indirect
 	github.com/go-viper/mapstructure/v2 v2.4.0 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
 	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
-	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/prometheus/client_model v0.6.2 // indirect
 	github.com/prometheus/common v0.66.1 // indirect
 	github.com/prometheus/procfs v0.16.1 // indirect
@@ -39,11 +34,7 @@ require (
 	go.uber.org/zap v1.26.0 // indirect
 	go.yaml.in/yaml/v2 v2.4.2 // indirect
 	go.yaml.in/yaml/v3 v3.0.4 // indirect
-	golang.org/x/mod v0.32.0 // indirect
-	golang.org/x/sync v0.19.0 // indirect
 	golang.org/x/sys v0.41.0 // indirect
 	golang.org/x/text v0.34.0 // indirect
-	golang.org/x/tools v0.41.0 // indirect
 	google.golang.org/protobuf v1.36.8 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -28,8 +28,6 @@ github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
 github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
-github.com/miekg/dns v1.1.72 h1:vhmr+TF2A3tuoGNkLDFK9zi36F2LS+hKTRW0Uf8kbzI=
-github.com/miekg/dns v1.1.72/go.mod h1:+EuEPhdHOsfk6Wk5TT2CzssZdqkmFhf8r+aVyDEToIs=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
 github.com/pelletier/go-toml/v2 v2.2.4 h1:mye9XuhQ6gvn5h28+VilKrrPoQVanw5PMw/TB0t5Ec4=
@@ -76,18 +74,12 @@ go.yaml.in/yaml/v2 v2.4.2 h1:DzmwEr2rDGHl7lsFgAHxmNz/1NlQ7xLIrlN2h5d1eGI=
 go.yaml.in/yaml/v2 v2.4.2/go.mod h1:081UH+NErpNdqlCXm3TtEran0rJZGxAYx9hb/ELlsPU=
 go.yaml.in/yaml/v3 v3.0.4 h1:tfq32ie2Jv2UxXFdLJdh3jXuOzWiL1fo0bu/FbuKpbc=
 go.yaml.in/yaml/v3 v3.0.4/go.mod h1:DhzuOOF2ATzADvBadXxruRBLzYTpT36CKvDb3+aBEFg=
-golang.org/x/mod v0.32.0 h1:9F4d3PHLljb6x//jOyokMv3eX+YDeepZSEo3mFJy93c=
-golang.org/x/mod v0.32.0/go.mod h1:SgipZ/3h2Ci89DlEtEXWUk/HteuRin+HHhN+WbNhguU=
 golang.org/x/net v0.50.0 h1:ucWh9eiCGyDR3vtzso0WMQinm2Dnt8cFMuQa9K33J60=
 golang.org/x/net v0.50.0/go.mod h1:UgoSli3F/pBgdJBHCTc+tp3gmrU4XswgGRgtnwWTfyM=
-golang.org/x/sync v0.19.0 h1:vV+1eWNmZ5geRlYjzm2adRgW2/mcpevXNg50YZtPCE4=
-golang.org/x/sync v0.19.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
 golang.org/x/sys v0.41.0 h1:Ivj+2Cp/ylzLiEU89QhWblYnOE9zerudt9Ftecq2C6k=
 golang.org/x/sys v0.41.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
 golang.org/x/text v0.34.0 h1:oL/Qq0Kdaqxa1KbNeMKwQq0reLCCaFtqu2eNuSeNHbk=
 golang.org/x/text v0.34.0/go.mod h1:homfLqTYRFyVYemLBFl5GgL/DWEiH5wcsQ5gSh1yziA=
-golang.org/x/tools v0.41.0 h1:a9b8iMweWG+S0OBnlU36rzLp20z1Rp10w+IY2czHTQc=
-golang.org/x/tools v0.41.0/go.mod h1:XSY6eDqxVNiYgezAVqqCeihT4j1U2CCsqvH3WhQpnlg=
 google.golang.org/protobuf v1.36.8 h1:xHScyCOEuuwZEc6UtSOvPbAT4zRh0xcNRYekJwfqyMc=
 google.golang.org/protobuf v1.36.8/go.mod h1:fuxRtAxBytpl4zzqUh6/eyUujkJdNiuEkXntxiD/uRU=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

internal/notify/notify.go

@@ -1,5 +1,4 @@
-// Package notify provides notification delivery to Slack,
+// Package notify provides notification delivery to Slack, Mattermost, and ntfy.
-// Mattermost, and ntfy.
 package notify
 
 import (
@@ -8,7 +7,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io"
 	"log/slog"
 	"net/http"
 	"net/url"
@@ -36,66 +34,8 @@ var (
 	ErrMattermostFailed = errors.New(
 		"mattermost notification failed",
 	)
-	// ErrInvalidScheme is returned for disallowed URL schemes.
-	ErrInvalidScheme = errors.New("URL scheme not allowed")
-	// ErrMissingHost is returned when a URL has no host.
-	ErrMissingHost = errors.New("URL must have a host")
 )
 
-// IsAllowedScheme checks if the URL scheme is permitted.
-func IsAllowedScheme(scheme string) bool {
-	return scheme == "https" || scheme == "http"
-}
-
-// ValidateWebhookURL validates and sanitizes a webhook URL.
-// It ensures the URL has an allowed scheme (http/https),
-// a non-empty host, and returns a pre-parsed *url.URL
-// reconstructed from validated components.
-func ValidateWebhookURL(raw string) (*url.URL, error) {
-	u, err := url.ParseRequestURI(raw)
-	if err != nil {
-		return nil, fmt.Errorf("invalid URL: %w", err)
-	}
-
-	if !IsAllowedScheme(u.Scheme) {
-		return nil, fmt.Errorf(
-			"%w: %s", ErrInvalidScheme, u.Scheme,
-		)
-	}
-
-	if u.Host == "" {
-		return nil, fmt.Errorf("%w", ErrMissingHost)
-	}
-
-	// Reconstruct from parsed components.
-	clean := &url.URL{
-		Scheme:   u.Scheme,
-		Host:     u.Host,
-		Path:     u.Path,
-		RawQuery: u.RawQuery,
-	}
-
-	return clean, nil
-}
-
-// newRequest creates an http.Request from a pre-validated *url.URL.
-// This avoids passing URL strings to http.NewRequestWithContext,
-// which gosec flags as a potential SSRF vector.
-func newRequest(
-	ctx context.Context,
-	method string,
-	target *url.URL,
-	body io.Reader,
-) *http.Request {
-	return (&http.Request{
-		Method: method,
-		URL:    target,
-		Host:   target.Host,
-		Header: make(http.Header),
-		Body:   io.NopCloser(body),
-	}).WithContext(ctx)
-}
-
 // Params contains dependencies for Service.
 type Params struct {
 	fx.In
@@ -107,7 +47,7 @@ type Params struct {
 // Service provides notification functionality.
 type Service struct {
 	log                  *slog.Logger
-	transport            http.RoundTripper
+	client               *http.Client
 	config               *config.Config
 	ntfyURL              *url.URL
 	slackWebhookURL      *url.URL
@@ -120,41 +60,33 @@ func New(
 	params Params,
 ) (*Service, error) {
 	svc := &Service{
-		log:       params.Logger.Get(),
+		log: params.Logger.Get(),
-		transport: http.DefaultTransport,
+		client: &http.Client{
-		config:    params.Config,
+			Timeout: httpClientTimeout,
+		},
+		config: params.Config,
 	}
 
 	if params.Config.NtfyTopic != "" {
-		u, err := ValidateWebhookURL(
+		u, err := url.ParseRequestURI(params.Config.NtfyTopic)
-			params.Config.NtfyTopic,
-		)
 		if err != nil {
-			return nil, fmt.Errorf(
+			return nil, fmt.Errorf("invalid ntfy topic URL: %w", err)
-				"invalid ntfy topic URL: %w", err,
-			)
 		}
 
 		svc.ntfyURL = u
 	}
 
 	if params.Config.SlackWebhook != "" {
-		u, err := ValidateWebhookURL(
+		u, err := url.ParseRequestURI(params.Config.SlackWebhook)
-			params.Config.SlackWebhook,
-		)
 		if err != nil {
-			return nil, fmt.Errorf(
+			return nil, fmt.Errorf("invalid slack webhook URL: %w", err)
-				"invalid slack webhook URL: %w", err,
-			)
 		}
 
 		svc.slackWebhookURL = u
 	}
 
 	if params.Config.MattermostWebhook != "" {
-		u, err := ValidateWebhookURL(
+		u, err := url.ParseRequestURI(params.Config.MattermostWebhook)
-			params.Config.MattermostWebhook,
-		)
 		if err != nil {
 			return nil, fmt.Errorf(
 				"invalid mattermost webhook URL: %w", err,
@@ -167,8 +99,7 @@ func New(
 	return svc, nil
 }
 
-// SendNotification sends a notification to all configured
+// SendNotification sends a notification to all configured endpoints.
-// endpoints.
 func (svc *Service) SendNotification(
 	ctx context.Context,
 	title, message, priority string,
@@ -239,20 +170,20 @@ func (svc *Service) sendNtfy(
 		"title", title,
 	)
 
-	ctx, cancel := context.WithTimeout(
+	request, err := http.NewRequestWithContext(
-		ctx, httpClientTimeout,
+		ctx,
-	)
+		http.MethodPost,
-	defer cancel()
+		topicURL.String(),
-
+		bytes.NewBufferString(message),
-	body := bytes.NewBufferString(message)
-	request := newRequest(
-		ctx, http.MethodPost, topicURL, body,
 	)
+	if err != nil {
+		return fmt.Errorf("creating ntfy request: %w", err)
+	}
 
 	request.Header.Set("Title", title)
 	request.Header.Set("Priority", ntfyPriority(priority))
 
-	resp, err := svc.transport.RoundTrip(request)
+	resp, err := svc.client.Do(request) //nolint:gosec // URL validated at Service construction time
 	if err != nil {
 		return fmt.Errorf("sending ntfy request: %w", err)
 	}
@@ -261,8 +192,7 @@ func (svc *Service) sendNtfy(
 
 	if resp.StatusCode >= httpStatusClientError {
 		return fmt.Errorf(
-			"%w: status %d",
+			"%w: status %d", ErrNtfyFailed, resp.StatusCode,
-			ErrNtfyFailed, resp.StatusCode,
 		)
 	}
 
@@ -302,11 +232,6 @@ func (svc *Service) sendSlack(
 	webhookURL *url.URL,
 	title, message, priority string,
 ) error {
-	ctx, cancel := context.WithTimeout(
-		ctx, httpClientTimeout,
-	)
-	defer cancel()
-
 	svc.log.Debug(
 		"sending webhook notification",
 		"url", webhookURL.String(),
@@ -325,19 +250,22 @@ func (svc *Service) sendSlack(
 
 	body, err := json.Marshal(payload)
 	if err != nil {
-		return fmt.Errorf(
+		return fmt.Errorf("marshaling webhook payload: %w", err)
-			"marshaling webhook payload: %w", err,
-		)
 	}
 
-	request := newRequest(
+	request, err := http.NewRequestWithContext(
-		ctx, http.MethodPost, webhookURL,
+		ctx,
+		http.MethodPost,
+		webhookURL.String(),
 		bytes.NewBuffer(body),
 	)
+	if err != nil {
+		return fmt.Errorf("creating webhook request: %w", err)
+	}
 
 	request.Header.Set("Content-Type", "application/json")
 
-	resp, err := svc.transport.RoundTrip(request)
+	resp, err := svc.client.Do(request) //nolint:gosec // URL validated at Service construction time
 	if err != nil {
 		return fmt.Errorf("sending webhook request: %w", err)
 	}

internal/notify/notify_test.go

@@ -1,100 +0,0 @@
-package notify_test
-
-import (
-	"testing"
-
-	"sneak.berlin/go/dnswatcher/internal/notify"
-)
-
-func TestValidateWebhookURLValid(t *testing.T) {
-	t.Parallel()
-
-	tests := []struct {
-		name    string
-		input   string
-		wantURL string
-	}{
-		{
-			name:    "valid https URL",
-			input:   "https://hooks.slack.com/T00/B00",
-			wantURL: "https://hooks.slack.com/T00/B00",
-		},
-		{
-			name:    "valid http URL",
-			input:   "http://localhost:8080/webhook",
-			wantURL: "http://localhost:8080/webhook",
-		},
-		{
-			name:    "https with query",
-			input:   "https://ntfy.sh/topic?auth=tok",
-			wantURL: "https://ntfy.sh/topic?auth=tok",
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			t.Parallel()
-
-			got, err := notify.ValidateWebhookURL(tt.input)
-			if err != nil {
-				t.Fatalf("unexpected error: %v", err)
-			}
-
-			if got.String() != tt.wantURL {
-				t.Errorf(
-					"got %q, want %q",
-					got.String(), tt.wantURL,
-				)
-			}
-		})
-	}
-}
-
-func TestValidateWebhookURLInvalid(t *testing.T) {
-	t.Parallel()
-
-	invalid := []struct {
-		name  string
-		input string
-	}{
-		{"ftp scheme", "ftp://example.com/file"},
-		{"file scheme", "file:///etc/passwd"},
-		{"empty string", ""},
-		{"no scheme", "example.com/webhook"},
-		{"no host", "https:///path"},
-	}
-
-	for _, tt := range invalid {
-		t.Run(tt.name, func(t *testing.T) {
-			t.Parallel()
-
-			got, err := notify.ValidateWebhookURL(tt.input)
-			if err == nil {
-				t.Errorf(
-					"expected error for %q, got %v",
-					tt.input, got,
-				)
-			}
-		})
-	}
-}
-
-func TestIsAllowedScheme(t *testing.T) {
-	t.Parallel()
-
-	if !notify.IsAllowedScheme("https") {
-		t.Error("https should be allowed")
-	}
-
-	if !notify.IsAllowedScheme("http") {
-		t.Error("http should be allowed")
-	}
-
-	if notify.IsAllowedScheme("ftp") {
-		t.Error("ftp should not be allowed")
-	}
-
-	if notify.IsAllowedScheme("") {
-		t.Error("empty scheme should not be allowed")
-	}
-}

internal/portcheck/portcheck.go

@@ -4,39 +4,18 @@ package portcheck
 import (
 	"context"
 	"errors"
-	"fmt"
 	"log/slog"
-	"net"
-	"strconv"
-	"sync"
-	"time"
 
 	"go.uber.org/fx"
-	"golang.org/x/sync/errgroup"
 
 	"sneak.berlin/go/dnswatcher/internal/logger"
 )
 
-const (
+// ErrNotImplemented indicates the port checker is not yet implemented.
-	minPort        = 1
+var ErrNotImplemented = errors.New(
-	maxPort        = 65535
+	"port checker not yet implemented",
-	defaultTimeout = 5 * time.Second
 )
 
-// ErrInvalidPort is returned when a port number is outside
-// the valid TCP range (1–65535).
-var ErrInvalidPort = errors.New("invalid port number")
-
-// PortResult holds the outcome of a single TCP port check.
-type PortResult struct {
-	// Open indicates whether the port accepted a connection.
-	Open bool
-	// Error contains a description if the connection failed.
-	Error string
-	// Latency is the time taken for the TCP handshake.
-	Latency time.Duration
-}
-
 // Params contains dependencies for Checker.
 type Params struct {
 	fx.In
@@ -59,145 +38,11 @@ func New(
 	}, nil
 }
 
-// NewStandalone creates a Checker without fx dependencies.
-func NewStandalone() *Checker {
-	return &Checker{
-		log: slog.Default(),
-	}
-}
-
-// validatePort checks that a port number is within the valid
-// TCP port range (1–65535).
-func validatePort(port int) error {
-	if port < minPort || port > maxPort {
-		return fmt.Errorf(
-			"%w: %d (must be between %d and %d)",
-			ErrInvalidPort, port, minPort, maxPort,
-		)
-	}
-
-	return nil
-}
-
 // CheckPort tests TCP connectivity to the given address and port.
-// It uses a 5-second timeout unless the context has an earlier
-// deadline.
 func (c *Checker) CheckPort(
-	ctx context.Context,
+	_ context.Context,
-	address string,
+	_ string,
-	port int,
+	_ int,
-) (*PortResult, error) {
+) (bool, error) {
-	err := validatePort(port)
+	return false, ErrNotImplemented
-	if err != nil {
-		return nil, err
-	}
-
-	target := net.JoinHostPort(
-		address, strconv.Itoa(port),
-	)
-
-	timeout := defaultTimeout
-
-	deadline, hasDeadline := ctx.Deadline()
-	if hasDeadline {
-		remaining := time.Until(deadline)
-		if remaining < timeout {
-			timeout = remaining
-		}
-	}
-
-	return c.checkConnection(ctx, target, timeout), nil
-}
-
-// CheckPorts tests TCP connectivity to multiple ports on the
-// given address concurrently. It returns a map of port number
-// to result.
-func (c *Checker) CheckPorts(
-	ctx context.Context,
-	address string,
-	ports []int,
-) (map[int]*PortResult, error) {
-	for _, port := range ports {
-		err := validatePort(port)
-		if err != nil {
-			return nil, err
-		}
-	}
-
-	var mu sync.Mutex
-
-	results := make(map[int]*PortResult, len(ports))
-
-	g, ctx := errgroup.WithContext(ctx)
-
-	for _, port := range ports {
-		g.Go(func() error {
-			result, err := c.CheckPort(ctx, address, port)
-			if err != nil {
-				return fmt.Errorf(
-					"checking port %d: %w", port, err,
-				)
-			}
-
-			mu.Lock()
-			results[port] = result
-			mu.Unlock()
-
-			return nil
-		})
-	}
-
-	err := g.Wait()
-	if err != nil {
-		return nil, err
-	}
-
-	return results, nil
-}
-
-// checkConnection performs the TCP dial and returns a result.
-func (c *Checker) checkConnection(
-	ctx context.Context,
-	target string,
-	timeout time.Duration,
-) *PortResult {
-	dialer := &net.Dialer{Timeout: timeout}
-	start := time.Now()
-
-	conn, dialErr := dialer.DialContext(ctx, "tcp", target)
-	latency := time.Since(start)
-
-	if dialErr != nil {
-		c.log.Debug(
-			"port check failed",
-			"target", target,
-			"error", dialErr.Error(),
-		)
-
-		return &PortResult{
-			Open:    false,
-			Error:   dialErr.Error(),
-			Latency: latency,
-		}
-	}
-
-	closeErr := conn.Close()
-	if closeErr != nil {
-		c.log.Debug(
-			"closing connection",
-			"target", target,
-			"error", closeErr.Error(),
-		)
-	}
-
-	c.log.Debug(
-		"port check succeeded",
-		"target", target,
-		"latency", latency,
-	)
-
-	return &PortResult{
-		Open:    true,
-		Latency: latency,
-	}
 }

internal/portcheck/portcheck_test.go

@@ -1,211 +0,0 @@
-package portcheck_test
-
-import (
-	"context"
-	"net"
-	"testing"
-	"time"
-
-	"sneak.berlin/go/dnswatcher/internal/portcheck"
-)
-
-func listenTCP(
-	t *testing.T,
-) (net.Listener, int) {
-	t.Helper()
-
-	lc := &net.ListenConfig{}
-
-	ln, err := lc.Listen(
-		context.Background(), "tcp", "127.0.0.1:0",
-	)
-	if err != nil {
-		t.Fatalf("failed to start listener: %v", err)
-	}
-
-	addr, ok := ln.Addr().(*net.TCPAddr)
-	if !ok {
-		t.Fatal("unexpected address type")
-	}
-
-	return ln, addr.Port
-}
-
-func TestCheckPortOpen(t *testing.T) {
-	t.Parallel()
-
-	ln, port := listenTCP(t)
-
-	defer func() { _ = ln.Close() }()
-
-	checker := portcheck.NewStandalone()
-
-	result, err := checker.CheckPort(
-		context.Background(), "127.0.0.1", port,
-	)
-	if err != nil {
-		t.Fatalf("unexpected error: %v", err)
-	}
-
-	if !result.Open {
-		t.Error("expected port to be open")
-	}
-
-	if result.Error != "" {
-		t.Errorf("expected no error, got: %s", result.Error)
-	}
-
-	if result.Latency <= 0 {
-		t.Error("expected positive latency")
-	}
-}
-
-func TestCheckPortClosed(t *testing.T) {
-	t.Parallel()
-
-	ln, port := listenTCP(t)
-	_ = ln.Close()
-
-	checker := portcheck.NewStandalone()
-
-	result, err := checker.CheckPort(
-		context.Background(), "127.0.0.1", port,
-	)
-	if err != nil {
-		t.Fatalf("unexpected error: %v", err)
-	}
-
-	if result.Open {
-		t.Error("expected port to be closed")
-	}
-
-	if result.Error == "" {
-		t.Error("expected error message for closed port")
-	}
-}
-
-func TestCheckPortContextCanceled(t *testing.T) {
-	t.Parallel()
-
-	ctx, cancel := context.WithCancel(context.Background())
-	cancel()
-
-	checker := portcheck.NewStandalone()
-
-	result, err := checker.CheckPort(ctx, "127.0.0.1", 1)
-	if err != nil {
-		t.Fatalf("unexpected error: %v", err)
-	}
-
-	if result.Open {
-		t.Error("expected port to not be open")
-	}
-}
-
-func TestCheckPortsMultiple(t *testing.T) {
-	t.Parallel()
-
-	ln, openPort := listenTCP(t)
-
-	defer func() { _ = ln.Close() }()
-
-	ln2, closedPort := listenTCP(t)
-	_ = ln2.Close()
-
-	checker := portcheck.NewStandalone()
-
-	results, err := checker.CheckPorts(
-		context.Background(),
-		"127.0.0.1",
-		[]int{openPort, closedPort},
-	)
-	if err != nil {
-		t.Fatalf("unexpected error: %v", err)
-	}
-
-	if len(results) != 2 {
-		t.Fatalf(
-			"expected 2 results, got %d", len(results),
-		)
-	}
-
-	if !results[openPort].Open {
-		t.Error("expected open port to be open")
-	}
-
-	if results[closedPort].Open {
-		t.Error("expected closed port to be closed")
-	}
-}
-
-func TestCheckPortInvalidPorts(t *testing.T) {
-	t.Parallel()
-
-	checker := portcheck.NewStandalone()
-
-	cases := []struct {
-		name string
-		port int
-	}{
-		{"zero", 0},
-		{"negative", -1},
-		{"too high", 65536},
-		{"very negative", -1000},
-		{"very high", 100000},
-	}
-
-	for _, tc := range cases {
-		t.Run(tc.name, func(t *testing.T) {
-			t.Parallel()
-
-			_, err := checker.CheckPort(
-				context.Background(), "127.0.0.1", tc.port,
-			)
-			if err == nil {
-				t.Errorf(
-					"expected error for port %d, got nil",
-					tc.port,
-				)
-			}
-		})
-	}
-}
-
-func TestCheckPortsInvalidPort(t *testing.T) {
-	t.Parallel()
-
-	checker := portcheck.NewStandalone()
-
-	_, err := checker.CheckPorts(
-		context.Background(),
-		"127.0.0.1",
-		[]int{80, 0, 443},
-	)
-	if err == nil {
-		t.Error("expected error for invalid port in list")
-	}
-}
-
-func TestCheckPortLatencyReasonable(t *testing.T) {
-	t.Parallel()
-
-	ln, port := listenTCP(t)
-
-	defer func() { _ = ln.Close() }()
-
-	checker := portcheck.NewStandalone()
-
-	result, err := checker.CheckPort(
-		context.Background(), "127.0.0.1", port,
-	)
-	if err != nil {
-		t.Fatalf("unexpected error: %v", err)
-	}
-
-	if result.Latency > time.Second {
-		t.Errorf(
-			"latency too high for localhost: %v",
-			result.Latency,
-		)
-	}
-}

internal/resolver/dns_client.go

@@ -1,48 +0,0 @@
-package resolver
-
-import (
-	"context"
-	"time"
-
-	"github.com/miekg/dns"
-)
-
-// DNSClient abstracts DNS wire-protocol exchanges so the resolver
-// can be tested without hitting real nameservers.
-type DNSClient interface {
-	ExchangeContext(
-		ctx context.Context,
-		msg *dns.Msg,
-		addr string,
-	) (*dns.Msg, time.Duration, error)
-}
-
-// udpClient wraps a real dns.Client for production use.
-type udpClient struct {
-	timeout time.Duration
-}
-
-func (c *udpClient) ExchangeContext(
-	ctx context.Context,
-	msg *dns.Msg,
-	addr string,
-) (*dns.Msg, time.Duration, error) {
-	cl := &dns.Client{Timeout: c.timeout}
-
-	return cl.ExchangeContext(ctx, msg, addr)
-}
-
-// tcpClient wraps a real dns.Client using TCP.
-type tcpClient struct {
-	timeout time.Duration
-}
-
-func (c *tcpClient) ExchangeContext(
-	ctx context.Context,
-	msg *dns.Msg,
-	addr string,
-) (*dns.Msg, time.Duration, error) {
-	cl := &dns.Client{Net: "tcp", Timeout: c.timeout}
-
-	return cl.ExchangeContext(ctx, msg, addr)
-}

internal/resolver/errors.go

@@ -1,27 +0,0 @@
-package resolver
-
-import "errors"
-
-// Sentinel errors returned by the resolver.
-var (
-	// ErrNotImplemented indicates a method is stubbed out.
-	ErrNotImplemented = errors.New(
-		"resolver not yet implemented",
-	)
-
-	// ErrNoNameservers is returned when no authoritative NS
-	// could be discovered for a domain.
-	ErrNoNameservers = errors.New(
-		"no authoritative nameservers found",
-	)
-
-	// ErrCNAMEDepthExceeded is returned when a CNAME chain
-	// exceeds MaxCNAMEDepth.
-	ErrCNAMEDepthExceeded = errors.New(
-		"CNAME chain depth exceeded",
-	)
-
-	// ErrContextCanceled wraps context cancellation for the
-	// resolver's iterative queries.
-	ErrContextCanceled = errors.New("context canceled")
-)

internal/resolver/iterative.go

@@ -1,725 +0,0 @@
-package resolver
-
-import (
-	"context"
-	"errors"
-	"fmt"
-	"net"
-	"sort"
-	"strings"
-	"time"
-
-	"github.com/miekg/dns"
-)
-
-const (
-	queryTimeoutDuration = 5 * time.Second
-	maxRetries           = 2
-	maxDelegation        = 20
-	timeoutMultiplier    = 2
-	minDomainLabels      = 2
-)
-
-// ErrRefused is returned when a DNS server refuses a query.
-var ErrRefused = errors.New("dns query refused")
-
-func rootServerList() []string {
-	return []string{
-		"198.41.0.4",     // a.root-servers.net
-		"170.247.170.2",  // b
-		"192.33.4.12",    // c
-		"199.7.91.13",    // d
-		"192.203.230.10", // e
-		"192.5.5.241",    // f
-		"192.112.36.4",   // g
-		"198.97.190.53",  // h
-		"192.36.148.17",  // i
-		"192.58.128.30",  // j
-		"193.0.14.129",   // k
-		"199.7.83.42",    // l
-		"202.12.27.33",   // m
-	}
-}
-
-func checkCtx(ctx context.Context) error {
-	err := ctx.Err()
-	if err != nil {
-		return ErrContextCanceled
-	}
-
-	return nil
-}
-
-func (r *Resolver) exchangeWithTimeout(
-	ctx context.Context,
-	msg *dns.Msg,
-	addr string,
-	attempt int,
-) (*dns.Msg, error) {
-	_ = attempt // timeout escalation handled by client config
-
-	resp, _, err := r.client.ExchangeContext(ctx, msg, addr)
-
-	return resp, err
-}
-
-func (r *Resolver) tryExchange(
-	ctx context.Context,
-	msg *dns.Msg,
-	addr string,
-) (*dns.Msg, error) {
-	var resp *dns.Msg
-
-	var err error
-
-	for attempt := range maxRetries {
-		if checkCtx(ctx) != nil {
-			return nil, ErrContextCanceled
-		}
-
-		resp, err = r.exchangeWithTimeout(
-			ctx, msg, addr, attempt,
-		)
-		if err == nil {
-			break
-		}
-	}
-
-	return resp, err
-}
-
-func (r *Resolver) retryTCP(
-	ctx context.Context,
-	msg *dns.Msg,
-	addr string,
-	resp *dns.Msg,
-) *dns.Msg {
-	if !resp.Truncated {
-		return resp
-	}
-
-	tcpResp, _, tcpErr := r.tcp.ExchangeContext(ctx, msg, addr)
-	if tcpErr == nil {
-		return tcpResp
-	}
-
-	return resp
-}
-
-// queryDNS sends a DNS query to a specific server IP.
-// Tries non-recursive first, falls back to recursive on
-// REFUSED (handles DNS interception environments).
-func (r *Resolver) queryDNS(
-	ctx context.Context,
-	serverIP string,
-	name string,
-	qtype uint16,
-) (*dns.Msg, error) {
-	if checkCtx(ctx) != nil {
-		return nil, ErrContextCanceled
-	}
-
-	name = dns.Fqdn(name)
-	addr := net.JoinHostPort(serverIP, "53")
-
-	msg := new(dns.Msg)
-	msg.SetQuestion(name, qtype)
-	msg.RecursionDesired = false
-
-	resp, err := r.tryExchange(ctx, msg, addr)
-	if err != nil {
-		return nil, fmt.Errorf("query %s @%s: %w", name, serverIP, err)
-	}
-
-	if resp.Rcode == dns.RcodeRefused {
-		msg.RecursionDesired = true
-
-		resp, err = r.tryExchange(ctx, msg, addr)
-		if err != nil {
-			return nil, fmt.Errorf(
-				"query %s @%s: %w", name, serverIP, err,
-			)
-		}
-
-		if resp.Rcode == dns.RcodeRefused {
-			return nil, fmt.Errorf(
-				"query %s @%s: %w", name, serverIP, ErrRefused,
-			)
-		}
-	}
-
-	resp = r.retryTCP(ctx, msg, addr, resp)
-
-	return resp, nil
-}
-
-func extractNSSet(rrs []dns.RR) []string {
-	nsSet := make(map[string]bool)
-
-	for _, rr := range rrs {
-		if ns, ok := rr.(*dns.NS); ok {
-			nsSet[strings.ToLower(ns.Ns)] = true
-		}
-	}
-
-	names := make([]string, 0, len(nsSet))
-	for n := range nsSet {
-		names = append(names, n)
-	}
-
-	sort.Strings(names)
-
-	return names
-}
-
-func extractGlue(rrs []dns.RR) map[string][]net.IP {
-	glue := make(map[string][]net.IP)
-
-	for _, rr := range rrs {
-		switch r := rr.(type) {
-		case *dns.A:
-			name := strings.ToLower(r.Hdr.Name)
-			glue[name] = append(glue[name], r.A)
-		case *dns.AAAA:
-			name := strings.ToLower(r.Hdr.Name)
-			glue[name] = append(glue[name], r.AAAA)
-		}
-	}
-
-	return glue
-}
-
-func glueIPs(nsNames []string, glue map[string][]net.IP) []string {
-	var ips []string
-
-	for _, ns := range nsNames {
-		for _, addr := range glue[ns] {
-			if v4 := addr.To4(); v4 != nil {
-				ips = append(ips, v4.String())
-			}
-		}
-	}
-
-	return ips
-}
-
-func (r *Resolver) followDelegation(
-	ctx context.Context,
-	domain string,
-	servers []string,
-) ([]string, error) {
-	for range maxDelegation {
-		if checkCtx(ctx) != nil {
-			return nil, ErrContextCanceled
-		}
-
-		resp, err := r.queryServers(
-			ctx, servers, domain, dns.TypeNS,
-		)
-		if err != nil {
-			return nil, err
-		}
-
-		ansNS := extractNSSet(resp.Answer)
-		if len(ansNS) > 0 {
-			return ansNS, nil
-		}
-
-		authNS := extractNSSet(resp.Ns)
-		if len(authNS) == 0 {
-			return r.resolveNSRecursive(ctx, domain)
-		}
-
-		glue := extractGlue(resp.Extra)
-		nextServers := glueIPs(authNS, glue)
-
-		if len(nextServers) == 0 {
-			nextServers = r.resolveNSIPs(ctx, authNS)
-		}
-
-		if len(nextServers) == 0 {
-			return nil, ErrNoNameservers
-		}
-
-		servers = nextServers
-	}
-
-	return nil, ErrNoNameservers
-}
-
-func (r *Resolver) queryServers(
-	ctx context.Context,
-	servers []string,
-	name string,
-	qtype uint16,
-) (*dns.Msg, error) {
-	var lastErr error
-
-	for _, ip := range servers {
-		if checkCtx(ctx) != nil {
-			return nil, ErrContextCanceled
-		}
-
-		resp, err := r.queryDNS(ctx, ip, name, qtype)
-		if err == nil {
-			return resp, nil
-		}
-
-		lastErr = err
-	}
-
-	return nil, fmt.Errorf("all servers failed: %w", lastErr)
-}
-
-func (r *Resolver) resolveNSIPs(
-	ctx context.Context,
-	nsNames []string,
-) []string {
-	var ips []string
-
-	for _, ns := range nsNames {
-		resolved, err := r.resolveARecord(ctx, ns)
-		if err == nil {
-			ips = append(ips, resolved...)
-		}
-
-		if len(ips) > 0 {
-			break
-		}
-	}
-
-	return ips
-}
-
-// resolveNSRecursive queries for NS records using recursive
-// resolution as a fallback for intercepted environments.
-func (r *Resolver) resolveNSRecursive(
-	ctx context.Context,
-	domain string,
-) ([]string, error) {
-	domain = dns.Fqdn(domain)
-	msg := new(dns.Msg)
-	msg.SetQuestion(domain, dns.TypeNS)
-	msg.RecursionDesired = true
-
-	for _, ip := range rootServerList()[:3] {
-		if checkCtx(ctx) != nil {
-			return nil, ErrContextCanceled
-		}
-
-		addr := net.JoinHostPort(ip, "53")
-
-		resp, _, err := r.client.ExchangeContext(ctx, msg, addr)
-		if err != nil {
-			continue
-		}
-
-		nsNames := extractNSSet(resp.Answer)
-		if len(nsNames) > 0 {
-			return nsNames, nil
-		}
-	}
-
-	return nil, ErrNoNameservers
-}
-
-// resolveARecord resolves a hostname to IPv4 addresses.
-func (r *Resolver) resolveARecord(
-	ctx context.Context,
-	hostname string,
-) ([]string, error) {
-	hostname = dns.Fqdn(hostname)
-	msg := new(dns.Msg)
-	msg.SetQuestion(hostname, dns.TypeA)
-	msg.RecursionDesired = true
-
-	for _, ip := range rootServerList()[:3] {
-		if checkCtx(ctx) != nil {
-			return nil, ErrContextCanceled
-		}
-
-		addr := net.JoinHostPort(ip, "53")
-
-		resp, _, err := r.client.ExchangeContext(ctx, msg, addr)
-		if err != nil {
-			continue
-		}
-
-		var ips []string
-
-		for _, rr := range resp.Answer {
-			if a, ok := rr.(*dns.A); ok {
-				ips = append(ips, a.A.String())
-			}
-		}
-
-		if len(ips) > 0 {
-			return ips, nil
-		}
-	}
-
-	return nil, fmt.Errorf(
-		"cannot resolve %s: %w", hostname, ErrNoNameservers,
-	)
-}
-
-// FindAuthoritativeNameservers traces the delegation chain from
-// root servers to discover all authoritative nameservers for the
-// given domain. Walks up the label hierarchy for subdomains.
-func (r *Resolver) FindAuthoritativeNameservers(
-	ctx context.Context,
-	domain string,
-) ([]string, error) {
-	if checkCtx(ctx) != nil {
-		return nil, ErrContextCanceled
-	}
-
-	domain = dns.Fqdn(strings.ToLower(domain))
-	labels := dns.SplitDomainName(domain)
-
-	for i := range labels {
-		if checkCtx(ctx) != nil {
-			return nil, ErrContextCanceled
-		}
-
-		candidate := strings.Join(labels[i:], ".") + "."
-
-		nsNames, err := r.followDelegation(
-			ctx, candidate, rootServerList(),
-		)
-		if err == nil && len(nsNames) > 0 {
-			sort.Strings(nsNames)
-
-			return nsNames, nil
-		}
-	}
-
-	return nil, ErrNoNameservers
-}
-
-// QueryNameserver queries a specific nameserver for all record
-// types and builds a NameserverResponse.
-func (r *Resolver) QueryNameserver(
-	ctx context.Context,
-	nsHostname string,
-	hostname string,
-) (*NameserverResponse, error) {
-	if checkCtx(ctx) != nil {
-		return nil, ErrContextCanceled
-	}
-
-	nsIPs, err := r.resolveARecord(ctx, nsHostname)
-	if err != nil {
-		return nil, fmt.Errorf("resolving NS %s: %w", nsHostname, err)
-	}
-
-	hostname = dns.Fqdn(hostname)
-
-	return r.queryAllTypes(ctx, nsHostname, nsIPs[0], hostname)
-}
-
-func (r *Resolver) queryAllTypes(
-	ctx context.Context,
-	nsHostname string,
-	nsIP string,
-	hostname string,
-) (*NameserverResponse, error) {
-	resp := &NameserverResponse{
-		Nameserver: nsHostname,
-		Records:    make(map[string][]string),
-		Status:     StatusOK,
-	}
-
-	qtypes := []uint16{
-		dns.TypeA, dns.TypeAAAA, dns.TypeCNAME,
-		dns.TypeMX, dns.TypeTXT, dns.TypeSRV,
-		dns.TypeCAA, dns.TypeNS,
-	}
-
-	state := r.queryEachType(ctx, nsIP, hostname, qtypes, resp)
-	classifyResponse(resp, state)
-
-	return resp, nil
-}
-
-type queryState struct {
-	gotNXDomain bool
-	gotSERVFAIL bool
-	hasRecords  bool
-}
-
-func (r *Resolver) queryEachType(
-	ctx context.Context,
-	nsIP string,
-	hostname string,
-	qtypes []uint16,
-	resp *NameserverResponse,
-) queryState {
-	var state queryState
-
-	for _, qtype := range qtypes {
-		if checkCtx(ctx) != nil {
-			break
-		}
-
-		r.querySingleType(ctx, nsIP, hostname, qtype, resp, &state)
-	}
-
-	for k := range resp.Records {
-		sort.Strings(resp.Records[k])
-	}
-
-	return state
-}
-
-func (r *Resolver) querySingleType(
-	ctx context.Context,
-	nsIP string,
-	hostname string,
-	qtype uint16,
-	resp *NameserverResponse,
-	state *queryState,
-) {
-	msg, err := r.queryDNS(ctx, nsIP, hostname, qtype)
-	if err != nil {
-		return
-	}
-
-	if msg.Rcode == dns.RcodeNameError {
-		state.gotNXDomain = true
-
-		return
-	}
-
-	if msg.Rcode == dns.RcodeServerFailure {
-		state.gotSERVFAIL = true
-
-		return
-	}
-
-	collectAnswerRecords(msg, resp, state)
-}
-
-func collectAnswerRecords(
-	msg *dns.Msg,
-	resp *NameserverResponse,
-	state *queryState,
-) {
-	for _, rr := range msg.Answer {
-		val := extractRecordValue(rr)
-		if val == "" {
-			continue
-		}
-
-		typeName := dns.TypeToString[rr.Header().Rrtype]
-		resp.Records[typeName] = append(
-			resp.Records[typeName], val,
-		)
-		state.hasRecords = true
-	}
-}
-
-func classifyResponse(resp *NameserverResponse, state queryState) {
-	switch {
-	case state.gotNXDomain && !state.hasRecords:
-		resp.Status = StatusNXDomain
-	case state.gotSERVFAIL && !state.hasRecords:
-		resp.Status = StatusError
-	case !state.hasRecords && !state.gotNXDomain:
-		resp.Status = StatusNoData
-	}
-}
-
-// extractRecordValue formats a DNS RR value as a string.
-func extractRecordValue(rr dns.RR) string {
-	switch r := rr.(type) {
-	case *dns.A:
-		return r.A.String()
-	case *dns.AAAA:
-		return r.AAAA.String()
-	case *dns.CNAME:
-		return r.Target
-	case *dns.MX:
-		return fmt.Sprintf("%d %s", r.Preference, r.Mx)
-	case *dns.TXT:
-		return strings.Join(r.Txt, "")
-	case *dns.SRV:
-		return fmt.Sprintf(
-			"%d %d %d %s",
-			r.Priority, r.Weight, r.Port, r.Target,
-		)
-	case *dns.CAA:
-		return fmt.Sprintf(
-			"%d %s \"%s\"", r.Flag, r.Tag, r.Value,
-		)
-	case *dns.NS:
-		return r.Ns
-	default:
-		return ""
-	}
-}
-
-// parentDomain returns the registerable parent domain.
-func parentDomain(hostname string) string {
-	hostname = dns.Fqdn(strings.ToLower(hostname))
-	labels := dns.SplitDomainName(hostname)
-
-	if len(labels) <= minDomainLabels {
-		return strings.Join(labels, ".") + "."
-	}
-
-	return strings.Join(
-		labels[len(labels)-minDomainLabels:], ".",
-	) + "."
-}
-
-// QueryAllNameservers discovers auth NSes for the hostname's
-// parent domain, then queries each one independently.
-func (r *Resolver) QueryAllNameservers(
-	ctx context.Context,
-	hostname string,
-) (map[string]*NameserverResponse, error) {
-	if checkCtx(ctx) != nil {
-		return nil, ErrContextCanceled
-	}
-
-	parent := parentDomain(hostname)
-
-	nameservers, err := r.FindAuthoritativeNameservers(ctx, parent)
-	if err != nil {
-		return nil, err
-	}
-
-	return r.queryEachNS(ctx, nameservers, hostname)
-}
-
-func (r *Resolver) queryEachNS(
-	ctx context.Context,
-	nameservers []string,
-	hostname string,
-) (map[string]*NameserverResponse, error) {
-	results := make(map[string]*NameserverResponse)
-
-	for _, ns := range nameservers {
-		if checkCtx(ctx) != nil {
-			return nil, ErrContextCanceled
-		}
-
-		resp, err := r.QueryNameserver(ctx, ns, hostname)
-		if err != nil {
-			results[ns] = &NameserverResponse{
-				Nameserver: ns,
-				Records:    make(map[string][]string),
-				Status:     StatusError,
-				Error:      err.Error(),
-			}
-
-			continue
-		}
-
-		results[ns] = resp
-	}
-
-	return results, nil
-}
-
-// LookupNS returns the NS record set for a domain.
-func (r *Resolver) LookupNS(
-	ctx context.Context,
-	domain string,
-) ([]string, error) {
-	return r.FindAuthoritativeNameservers(ctx, domain)
-}
-
-// LookupAllRecords performs iterative resolution to find all DNS
-// records for the given hostname, keyed by authoritative nameserver.
-func (r *Resolver) LookupAllRecords(
-	ctx context.Context,
-	hostname string,
-) (map[string]map[string][]string, error) {
-	results, err := r.QueryAllNameservers(ctx, hostname)
-	if err != nil {
-		return nil, err
-	}
-
-	out := make(map[string]map[string][]string, len(results))
-	for ns, resp := range results {
-		out[ns] = resp.Records
-	}
-
-	return out, nil
-}
-
-// ResolveIPAddresses resolves a hostname to all IPv4 and IPv6
-// addresses, following CNAME chains up to MaxCNAMEDepth.
-func (r *Resolver) ResolveIPAddresses(
-	ctx context.Context,
-	hostname string,
-) ([]string, error) {
-	if checkCtx(ctx) != nil {
-		return nil, ErrContextCanceled
-	}
-
-	return r.resolveIPWithCNAME(ctx, hostname, 0)
-}
-
-func (r *Resolver) resolveIPWithCNAME(
-	ctx context.Context,
-	hostname string,
-	depth int,
-) ([]string, error) {
-	if depth > MaxCNAMEDepth {
-		return nil, ErrCNAMEDepthExceeded
-	}
-
-	results, err := r.QueryAllNameservers(ctx, hostname)
-	if err != nil {
-		return nil, err
-	}
-
-	ips, cnameTarget := collectIPs(results)
-
-	if len(ips) == 0 && cnameTarget != "" {
-		return r.resolveIPWithCNAME(ctx, cnameTarget, depth+1)
-	}
-
-	sort.Strings(ips)
-
-	return ips, nil
-}
-
-func collectIPs(
-	results map[string]*NameserverResponse,
-) ([]string, string) {
-	seen := make(map[string]bool)
-
-	var ips []string
-
-	var cnameTarget string
-
-	for _, resp := range results {
-		if resp.Status == StatusNXDomain {
-			continue
-		}
-
-		for _, ip := range resp.Records["A"] {
-			if !seen[ip] {
-				seen[ip] = true
-				ips = append(ips, ip)
-			}
-		}
-
-		for _, ip := range resp.Records["AAAA"] {
-			if !seen[ip] {
-				seen[ip] = true
-				ips = append(ips, ip)
-			}
-		}
-
-		if len(resp.Records["CNAME"]) > 0 && cnameTarget == "" {
-			cnameTarget = resp.Records["CNAME"][0]
-		}
-	}
-
-	return ips, cnameTarget
-}

internal/resolver/resolver.go

@@ -1,9 +1,9 @@
 // Package resolver provides iterative DNS resolution from root nameservers.
-// It traces the full delegation chain from IANA root servers through TLD
-// and domain nameservers, never relying on upstream recursive resolvers.
 package resolver
 
 import (
+	"context"
+	"errors"
 	"log/slog"
 
 	"go.uber.org/fx"
@@ -11,16 +11,8 @@ import (
 	"sneak.berlin/go/dnswatcher/internal/logger"
 )
 
-// Query status constants matching the state model.
+// ErrNotImplemented indicates the resolver is not yet implemented.
-const (
+var ErrNotImplemented = errors.New("resolver not yet implemented")
-	StatusOK       = "ok"
-	StatusError    = "error"
-	StatusNXDomain = "nxdomain"
-	StatusNoData   = "nodata"
-)
-
-// MaxCNAMEDepth is the maximum CNAME chain depth to follow.
-const MaxCNAMEDepth = 10
 
 // Params contains dependencies for Resolver.
 type Params struct {
@@ -29,54 +21,44 @@ type Params struct {
 	Logger *logger.Logger
 }
 
-// NameserverResponse holds one nameserver's response for a query.
-type NameserverResponse struct {
-	Nameserver string
-	Records    map[string][]string
-	Status     string
-	Error      string
-}
-
 // Resolver performs iterative DNS resolution from root servers.
 type Resolver struct {
-	log    *slog.Logger
+	log *slog.Logger
-	client DNSClient
-	tcp    DNSClient
 }
 
-// New creates a new Resolver instance for use with uber/fx.
+// New creates a new Resolver instance.
 func New(
 	_ fx.Lifecycle,
 	params Params,
 ) (*Resolver, error) {
 	return &Resolver{
-		log:    params.Logger.Get(),
+		log: params.Logger.Get(),
-		client: &udpClient{timeout: queryTimeoutDuration},
-		tcp:    &tcpClient{timeout: queryTimeoutDuration},
 	}, nil
 }
 
-// NewFromLogger creates a Resolver directly from an slog.Logger,
+// LookupNS performs iterative resolution to find authoritative
-// useful for testing without the fx lifecycle.
+// nameservers for the given domain.
-func NewFromLogger(log *slog.Logger) *Resolver {
+func (r *Resolver) LookupNS(
-	return &Resolver{
+	_ context.Context,
-		log:    log,
+	_ string,
-		client: &udpClient{timeout: queryTimeoutDuration},
+) ([]string, error) {
-		tcp:    &tcpClient{timeout: queryTimeoutDuration},
+	return nil, ErrNotImplemented
-	}
 }
 
-// NewFromLoggerWithClient creates a Resolver with a custom DNS
+// LookupAllRecords performs iterative resolution to find all DNS
-// client, useful for testing with mock DNS responses.
+// records for the given hostname, keyed by authoritative nameserver.
-func NewFromLoggerWithClient(
+func (r *Resolver) LookupAllRecords(
-	log *slog.Logger,
+	_ context.Context,
-	client DNSClient,
+	_ string,
-) *Resolver {
+) (map[string]map[string][]string, error) {
-	return &Resolver{
+	return nil, ErrNotImplemented
-		log:    log,
-		client: client,
-		tcp:    client,
-	}
 }
 
-// Method implementations are in iterative.go.
+// ResolveIPAddresses resolves a hostname to all IPv4 and IPv6
+// addresses, following CNAME chains.
+func (r *Resolver) ResolveIPAddresses(
+	_ context.Context,
+	_ string,
+) ([]string, error) {
+	return nil, ErrNotImplemented
+}

internal/resolver/resolver_test.go

@@ -1,634 +0,0 @@
-package resolver_test
-
-import (
-	"context"
-	"log/slog"
-	"net"
-	"os"
-	"sort"
-	"strings"
-	"testing"
-	"time"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-
-	"sneak.berlin/go/dnswatcher/internal/resolver"
-)
-
-// ----------------------------------------------------------------
-// Test helpers
-// ----------------------------------------------------------------
-
-func newTestResolver(t *testing.T) *resolver.Resolver {
-	t.Helper()
-
-	log := slog.New(slog.NewTextHandler(
-		os.Stderr,
-		&slog.HandlerOptions{Level: slog.LevelDebug},
-	))
-
-	return resolver.NewFromLogger(log)
-}
-
-func testContext(t *testing.T) context.Context {
-	t.Helper()
-
-	ctx, cancel := context.WithTimeout(
-		context.Background(), 60*time.Second,
-	)
-	t.Cleanup(cancel)
-
-	return ctx
-}
-
-func findOneNSForDomain(
-	t *testing.T,
-	r *resolver.Resolver,
-	ctx context.Context, //nolint:revive // test helper
-	domain string,
-) string {
-	t.Helper()
-
-	nameservers, err := r.FindAuthoritativeNameservers(
-		ctx, domain,
-	)
-	require.NoError(t, err)
-	require.NotEmpty(t, nameservers)
-
-	return nameservers[0]
-}
-
-// ----------------------------------------------------------------
-// FindAuthoritativeNameservers tests
-// ----------------------------------------------------------------
-
-func TestFindAuthoritativeNameservers_ValidDomain(
-	t *testing.T,
-) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-
-	nameservers, err := r.FindAuthoritativeNameservers(
-		ctx, "google.com",
-	)
-	require.NoError(t, err)
-	require.NotEmpty(t, nameservers)
-
-	hasGoogleNS := false
-
-	for _, ns := range nameservers {
-		if strings.Contains(ns, "google") {
-			hasGoogleNS = true
-
-			break
-		}
-	}
-
-	assert.True(t, hasGoogleNS,
-		"expected google nameservers, got: %v", nameservers,
-	)
-}
-
-func TestFindAuthoritativeNameservers_Subdomain(
-	t *testing.T,
-) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-
-	nameservers, err := r.FindAuthoritativeNameservers(
-		ctx, "www.google.com",
-	)
-	require.NoError(t, err)
-	require.NotEmpty(t, nameservers)
-}
-
-func TestFindAuthoritativeNameservers_ReturnsSorted(
-	t *testing.T,
-) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-
-	nameservers, err := r.FindAuthoritativeNameservers(
-		ctx, "google.com",
-	)
-	require.NoError(t, err)
-
-	assert.True(
-		t,
-		sort.StringsAreSorted(nameservers),
-		"nameservers should be sorted, got: %v", nameservers,
-	)
-}
-
-func TestFindAuthoritativeNameservers_Deterministic(
-	t *testing.T,
-) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-
-	first, err := r.FindAuthoritativeNameservers(
-		ctx, "google.com",
-	)
-	require.NoError(t, err)
-
-	second, err := r.FindAuthoritativeNameservers(
-		ctx, "google.com",
-	)
-	require.NoError(t, err)
-
-	assert.Equal(t, first, second)
-}
-
-func TestFindAuthoritativeNameservers_TrailingDot(
-	t *testing.T,
-) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-
-	ns1, err := r.FindAuthoritativeNameservers(
-		ctx, "google.com",
-	)
-	require.NoError(t, err)
-
-	ns2, err := r.FindAuthoritativeNameservers(
-		ctx, "google.com.",
-	)
-	require.NoError(t, err)
-
-	assert.Equal(t, ns1, ns2)
-}
-
-func TestFindAuthoritativeNameservers_CloudflareDomain(
-	t *testing.T,
-) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-
-	nameservers, err := r.FindAuthoritativeNameservers(
-		ctx, "cloudflare.com",
-	)
-	require.NoError(t, err)
-	require.NotEmpty(t, nameservers)
-
-	for _, ns := range nameservers {
-		assert.True(t, strings.HasSuffix(ns, "."),
-			"NS should be FQDN with trailing dot: %s", ns,
-		)
-	}
-}
-
-// ----------------------------------------------------------------
-// QueryNameserver tests
-// ----------------------------------------------------------------
-
-func TestQueryNameserver_BasicA(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-	ns := findOneNSForDomain(t, r, ctx, "google.com")
-
-	resp, err := r.QueryNameserver(
-		ctx, ns, "www.google.com",
-	)
-	require.NoError(t, err)
-	require.NotNil(t, resp)
-
-	assert.Equal(t, resolver.StatusOK, resp.Status)
-	assert.Equal(t, ns, resp.Nameserver)
-
-	hasRecords := len(resp.Records["A"]) > 0 ||
-		len(resp.Records["CNAME"]) > 0
-	assert.True(t, hasRecords,
-		"expected A or CNAME records for www.google.com",
-	)
-}
-
-func TestQueryNameserver_AAAA(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-	ns := findOneNSForDomain(t, r, ctx, "cloudflare.com")
-
-	resp, err := r.QueryNameserver(
-		ctx, ns, "cloudflare.com",
-	)
-	require.NoError(t, err)
-
-	aaaaRecords := resp.Records["AAAA"]
-	require.NotEmpty(t, aaaaRecords,
-		"cloudflare.com should have AAAA records",
-	)
-
-	for _, ip := range aaaaRecords {
-		parsed := net.ParseIP(ip)
-		require.NotNil(t, parsed,
-			"should be valid IP: %s", ip,
-		)
-	}
-}
-
-func TestQueryNameserver_MX(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-	ns := findOneNSForDomain(t, r, ctx, "google.com")
-
-	resp, err := r.QueryNameserver(
-		ctx, ns, "google.com",
-	)
-	require.NoError(t, err)
-
-	mxRecords := resp.Records["MX"]
-	require.NotEmpty(t, mxRecords,
-		"google.com should have MX records",
-	)
-}
-
-func TestQueryNameserver_TXT(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-	ns := findOneNSForDomain(t, r, ctx, "google.com")
-
-	resp, err := r.QueryNameserver(
-		ctx, ns, "google.com",
-	)
-	require.NoError(t, err)
-
-	txtRecords := resp.Records["TXT"]
-	require.NotEmpty(t, txtRecords,
-		"google.com should have TXT records",
-	)
-
-	hasSPF := false
-
-	for _, txt := range txtRecords {
-		if strings.Contains(txt, "v=spf1") {
-			hasSPF = true
-
-			break
-		}
-	}
-
-	assert.True(t, hasSPF,
-		"google.com should have SPF TXT record",
-	)
-}
-
-func TestQueryNameserver_NXDomain(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-	ns := findOneNSForDomain(t, r, ctx, "google.com")
-
-	resp, err := r.QueryNameserver(
-		ctx, ns,
-		"this-surely-does-not-exist-xyz.google.com",
-	)
-	require.NoError(t, err)
-
-	assert.Equal(t, resolver.StatusNXDomain, resp.Status)
-}
-
-func TestQueryNameserver_RecordsSorted(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-	ns := findOneNSForDomain(t, r, ctx, "google.com")
-
-	resp, err := r.QueryNameserver(
-		ctx, ns, "google.com",
-	)
-	require.NoError(t, err)
-
-	for recordType, values := range resp.Records {
-		assert.True(
-			t,
-			sort.StringsAreSorted(values),
-			"%s records should be sorted", recordType,
-		)
-	}
-}
-
-func TestQueryNameserver_ResponseIncludesNameserver(
-	t *testing.T,
-) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-	ns := findOneNSForDomain(t, r, ctx, "cloudflare.com")
-
-	resp, err := r.QueryNameserver(
-		ctx, ns, "cloudflare.com",
-	)
-	require.NoError(t, err)
-
-	assert.Equal(t, ns, resp.Nameserver)
-}
-
-func TestQueryNameserver_EmptyRecordsOnNXDomain(
-	t *testing.T,
-) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-	ns := findOneNSForDomain(t, r, ctx, "google.com")
-
-	resp, err := r.QueryNameserver(
-		ctx, ns,
-		"this-surely-does-not-exist-xyz.google.com",
-	)
-	require.NoError(t, err)
-
-	totalRecords := 0
-	for _, values := range resp.Records {
-		totalRecords += len(values)
-	}
-
-	assert.Zero(t, totalRecords)
-}
-
-func TestQueryNameserver_TrailingDotHandling(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-	ns := findOneNSForDomain(t, r, ctx, "google.com")
-
-	resp1, err := r.QueryNameserver(
-		ctx, ns, "google.com",
-	)
-	require.NoError(t, err)
-
-	resp2, err := r.QueryNameserver(
-		ctx, ns, "google.com.",
-	)
-	require.NoError(t, err)
-
-	assert.Equal(t, resp1.Status, resp2.Status)
-}
-
-// ----------------------------------------------------------------
-// QueryAllNameservers tests
-// ----------------------------------------------------------------
-
-func TestQueryAllNameservers_ReturnsAllNS(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-
-	results, err := r.QueryAllNameservers(
-		ctx, "google.com",
-	)
-	require.NoError(t, err)
-	require.NotEmpty(t, results)
-
-	assert.GreaterOrEqual(t, len(results), 2)
-
-	for ns, resp := range results {
-		assert.Equal(t, ns, resp.Nameserver)
-	}
-}
-
-func TestQueryAllNameservers_AllReturnOK(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-
-	results, err := r.QueryAllNameservers(
-		ctx, "google.com",
-	)
-	require.NoError(t, err)
-
-	for ns, resp := range results {
-		assert.Equal(
-			t, resolver.StatusOK, resp.Status,
-			"NS %s should return OK", ns,
-		)
-	}
-}
-
-func TestQueryAllNameservers_NXDomainFromAllNS(
-	t *testing.T,
-) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-
-	results, err := r.QueryAllNameservers(
-		ctx,
-		"this-surely-does-not-exist-xyz.google.com",
-	)
-	require.NoError(t, err)
-
-	for ns, resp := range results {
-		assert.Equal(
-			t, resolver.StatusNXDomain, resp.Status,
-			"NS %s should return nxdomain", ns,
-		)
-	}
-}
-
-// ----------------------------------------------------------------
-// LookupNS tests
-// ----------------------------------------------------------------
-
-func TestLookupNS_ValidDomain(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-
-	nameservers, err := r.LookupNS(ctx, "google.com")
-	require.NoError(t, err)
-	require.NotEmpty(t, nameservers)
-
-	for _, ns := range nameservers {
-		assert.True(t, strings.HasSuffix(ns, "."),
-			"NS should have trailing dot: %s", ns,
-		)
-	}
-}
-
-func TestLookupNS_Sorted(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-
-	nameservers, err := r.LookupNS(ctx, "google.com")
-	require.NoError(t, err)
-
-	assert.True(t, sort.StringsAreSorted(nameservers))
-}
-
-func TestLookupNS_MatchesFindAuthoritative(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-
-	fromLookup, err := r.LookupNS(ctx, "google.com")
-	require.NoError(t, err)
-
-	fromFind, err := r.FindAuthoritativeNameservers(
-		ctx, "google.com",
-	)
-	require.NoError(t, err)
-
-	assert.Equal(t, fromFind, fromLookup)
-}
-
-// ----------------------------------------------------------------
-// ResolveIPAddresses tests
-// ----------------------------------------------------------------
-
-func TestResolveIPAddresses_ReturnsIPs(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-
-	ips, err := r.ResolveIPAddresses(ctx, "google.com")
-	require.NoError(t, err)
-	require.NotEmpty(t, ips)
-
-	for _, ip := range ips {
-		parsed := net.ParseIP(ip)
-		assert.NotNil(t, parsed,
-			"should be valid IP: %s", ip,
-		)
-	}
-}
-
-func TestResolveIPAddresses_Deduplicated(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-
-	ips, err := r.ResolveIPAddresses(ctx, "google.com")
-	require.NoError(t, err)
-
-	seen := make(map[string]bool)
-
-	for _, ip := range ips {
-		assert.False(t, seen[ip], "duplicate IP: %s", ip)
-		seen[ip] = true
-	}
-}
-
-func TestResolveIPAddresses_Sorted(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-
-	ips, err := r.ResolveIPAddresses(ctx, "google.com")
-	require.NoError(t, err)
-
-	assert.True(t, sort.StringsAreSorted(ips))
-}
-
-func TestResolveIPAddresses_NXDomainReturnsEmpty(
-	t *testing.T,
-) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-
-	ips, err := r.ResolveIPAddresses(
-		ctx,
-		"this-surely-does-not-exist-xyz.google.com",
-	)
-	require.NoError(t, err)
-	assert.Empty(t, ips)
-}
-
-func TestResolveIPAddresses_CloudflareDomain(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx := testContext(t)
-
-	ips, err := r.ResolveIPAddresses(ctx, "cloudflare.com")
-	require.NoError(t, err)
-	require.NotEmpty(t, ips)
-}
-
-// ----------------------------------------------------------------
-// Context cancellation tests
-// ----------------------------------------------------------------
-
-func TestFindAuthoritativeNameservers_ContextCanceled(
-	t *testing.T,
-) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx, cancel := context.WithCancel(context.Background())
-	cancel()
-
-	_, err := r.FindAuthoritativeNameservers(ctx, "google.com")
-	assert.Error(t, err)
-}
-
-func TestQueryNameserver_ContextCanceled(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx, cancel := context.WithCancel(context.Background())
-	cancel()
-
-	_, err := r.QueryNameserver(
-		ctx, "ns1.google.com.", "google.com",
-	)
-	assert.Error(t, err)
-}
-
-func TestQueryAllNameservers_ContextCanceled(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx, cancel := context.WithCancel(context.Background())
-	cancel()
-
-	_, err := r.QueryAllNameservers(ctx, "google.com")
-	assert.Error(t, err)
-}
-
-func TestResolveIPAddresses_ContextCanceled(t *testing.T) {
-	t.Parallel()
-
-	r := newTestResolver(t)
-	ctx, cancel := context.WithCancel(context.Background())
-	cancel()
-
-	_, err := r.ResolveIPAddresses(ctx, "google.com")
-	assert.Error(t, err)
-}

internal/tlscheck/extractcertinfo_test.go

@@ -1,67 +0,0 @@
-package tlscheck_test
-
-import (
-	"context"
-	"crypto/tls"
-	"errors"
-	"net"
-	"testing"
-	"time"
-
-	"sneak.berlin/go/dnswatcher/internal/tlscheck"
-)
-
-func TestCheckCertificateNoPeerCerts(t *testing.T) {
-	t.Parallel()
-
-	lc := &net.ListenConfig{}
-
-	ln, err := lc.Listen(
-		context.Background(), "tcp", "127.0.0.1:0",
-	)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	defer func() { _ = ln.Close() }()
-
-	addr, ok := ln.Addr().(*net.TCPAddr)
-	if !ok {
-		t.Fatal("unexpected address type")
-	}
-
-	// Accept and immediately close to cause TLS handshake failure.
-	go func() {
-		conn, err := ln.Accept()
-		if err != nil {
-			return
-		}
-
-		_ = conn.Close()
-	}()
-
-	checker := tlscheck.NewStandalone(
-		tlscheck.WithTimeout(2*time.Second),
-		tlscheck.WithTLSConfig(&tls.Config{
-			InsecureSkipVerify: true, //nolint:gosec // test
-			MinVersion:         tls.VersionTLS12,
-		}),
-		tlscheck.WithPort(addr.Port),
-	)
-
-	_, err = checker.CheckCertificate(
-		context.Background(), "127.0.0.1", "localhost",
-	)
-	if err == nil {
-		t.Fatal("expected error when server presents no certs")
-	}
-}
-
-func TestErrNoPeerCertificatesIsSentinel(t *testing.T) {
-	t.Parallel()
-
-	err := tlscheck.ErrNoPeerCertificates
-	if !errors.Is(err, tlscheck.ErrNoPeerCertificates) {
-		t.Fatal("expected sentinel error to match")
-	}
-}

internal/tlscheck/tlscheck.go

@@ -3,12 +3,8 @@ package tlscheck
 
 import (
 	"context"
-	"crypto/tls"
 	"errors"
-	"fmt"
 	"log/slog"
-	"net"
-	"strconv"
 	"time"
 
 	"go.uber.org/fx"
@@ -16,56 +12,11 @@ import (
 	"sneak.berlin/go/dnswatcher/internal/logger"
 )
 
-const (
+// ErrNotImplemented indicates the TLS checker is not yet implemented.
-	defaultTimeout = 10 * time.Second
+var ErrNotImplemented = errors.New(
-	defaultPort    = 443
+	"tls checker not yet implemented",
 )
 
-// ErrUnexpectedConnType indicates the connection was not a TLS
-// connection.
-var ErrUnexpectedConnType = errors.New(
-	"unexpected connection type",
-)
-
-// ErrNoPeerCertificates indicates the TLS connection had no peer
-// certificates.
-var ErrNoPeerCertificates = errors.New(
-	"no peer certificates",
-)
-
-// CertificateInfo holds information about a TLS certificate.
-type CertificateInfo struct {
-	CommonName              string
-	Issuer                  string
-	NotAfter                time.Time
-	SubjectAlternativeNames []string
-	SerialNumber            string
-}
-
-// Option configures a Checker.
-type Option func(*Checker)
-
-// WithTimeout sets the connection timeout.
-func WithTimeout(d time.Duration) Option {
-	return func(c *Checker) {
-		c.timeout = d
-	}
-}
-
-// WithTLSConfig sets a custom TLS configuration.
-func WithTLSConfig(cfg *tls.Config) Option {
-	return func(c *Checker) {
-		c.tlsConfig = cfg
-	}
-}
-
-// WithPort sets the TLS port to connect to.
-func WithPort(port int) Option {
-	return func(c *Checker) {
-		c.port = port
-	}
-}
-
 // Params contains dependencies for Checker.
 type Params struct {
 	fx.In
@@ -75,10 +26,15 @@ type Params struct {
 
 // Checker performs TLS certificate inspection.
 type Checker struct {
-	log       *slog.Logger
+	log *slog.Logger
-	timeout   time.Duration
+}
-	tlsConfig *tls.Config
+
-	port      int
+// CertificateInfo holds information about a TLS certificate.
+type CertificateInfo struct {
+	CommonName              string
+	Issuer                  string
+	NotAfter                time.Time
+	SubjectAlternativeNames []string
 }
 
 // New creates a new TLS Checker instance.
@@ -87,110 +43,16 @@ func New(
 	params Params,
 ) (*Checker, error) {
 	return &Checker{
-		log:     params.Logger.Get(),
+		log: params.Logger.Get(),
-		timeout: defaultTimeout,
-		port:    defaultPort,
 	}, nil
 }
 
-// NewStandalone creates a Checker without fx dependencies.
+// CheckCertificate connects to the given IP:port using SNI and
-func NewStandalone(opts ...Option) *Checker {
+// returns certificate information.
-	checker := &Checker{
-		log:     slog.Default(),
-		timeout: defaultTimeout,
-		port:    defaultPort,
-	}
-
-	for _, opt := range opts {
-		opt(checker)
-	}
-
-	return checker
-}
-
-// CheckCertificate connects to the given IP address using the
-// specified SNI hostname and returns certificate information.
 func (c *Checker) CheckCertificate(
-	ctx context.Context,
+	_ context.Context,
-	ipAddress string,
+	_ string,
-	sniHostname string,
+	_ string,
 ) (*CertificateInfo, error) {
-	target := net.JoinHostPort(
+	return nil, ErrNotImplemented
-		ipAddress, strconv.Itoa(c.port),
-	)
-
-	tlsCfg := c.buildTLSConfig(sniHostname)
-	dialer := &tls.Dialer{
-		NetDialer: &net.Dialer{Timeout: c.timeout},
-		Config:    tlsCfg,
-	}
-
-	conn, err := dialer.DialContext(ctx, "tcp", target)
-	if err != nil {
-		return nil, fmt.Errorf(
-			"TLS dial to %s: %w", target, err,
-		)
-	}
-
-	defer func() {
-		closeErr := conn.Close()
-		if closeErr != nil {
-			c.log.Debug(
-				"closing TLS connection",
-				"target", target,
-				"error", closeErr.Error(),
-			)
-		}
-	}()
-
-	tlsConn, ok := conn.(*tls.Conn)
-	if !ok {
-		return nil, fmt.Errorf(
-			"%s: %w", target, ErrUnexpectedConnType,
-		)
-	}
-
-	return c.extractCertInfo(tlsConn)
-}
-
-func (c *Checker) buildTLSConfig(
-	sniHostname string,
-) *tls.Config {
-	if c.tlsConfig != nil {
-		cfg := c.tlsConfig.Clone()
-		cfg.ServerName = sniHostname
-
-		return cfg
-	}
-
-	return &tls.Config{
-		ServerName: sniHostname,
-		MinVersion: tls.VersionTLS12,
-	}
-}
-
-func (c *Checker) extractCertInfo(
-	conn *tls.Conn,
-) (*CertificateInfo, error) {
-	state := conn.ConnectionState()
-	if len(state.PeerCertificates) == 0 {
-		return nil, ErrNoPeerCertificates
-	}
-
-	cert := state.PeerCertificates[0]
-
-	sans := make([]string, 0, len(cert.DNSNames)+len(cert.IPAddresses))
-	sans = append(sans, cert.DNSNames...)
-
-	for _, ip := range cert.IPAddresses {
-		sans = append(sans, ip.String())
-	}
-
-	return &CertificateInfo{
-		CommonName:              cert.Subject.CommonName,
-		Issuer:                  cert.Issuer.CommonName,
-		NotAfter:                cert.NotAfter,
-		SubjectAlternativeNames: sans,
-		SerialNumber:            cert.SerialNumber.String(),
-	}, nil
 }

internal/tlscheck/tlscheck_test.go

@@ -1,169 +0,0 @@
-package tlscheck_test
-
-import (
-	"context"
-	"crypto/tls"
-	"net"
-	"net/http"
-	"net/http/httptest"
-	"testing"
-	"time"
-
-	"sneak.berlin/go/dnswatcher/internal/tlscheck"
-)
-
-func startTLSServer(
-	t *testing.T,
-) (*httptest.Server, string, int) {
-	t.Helper()
-
-	srv := httptest.NewTLSServer(
-		http.HandlerFunc(
-			func(w http.ResponseWriter, _ *http.Request) {
-				w.WriteHeader(http.StatusOK)
-			},
-		),
-	)
-
-	addr, ok := srv.Listener.Addr().(*net.TCPAddr)
-	if !ok {
-		t.Fatal("unexpected address type")
-	}
-
-	return srv, addr.IP.String(), addr.Port
-}
-
-func TestCheckCertificateValid(t *testing.T) {
-	t.Parallel()
-
-	srv, ip, port := startTLSServer(t)
-
-	defer srv.Close()
-
-	checker := tlscheck.NewStandalone(
-		tlscheck.WithTimeout(5*time.Second),
-		tlscheck.WithTLSConfig(&tls.Config{
-			//nolint:gosec // test uses self-signed cert
-			InsecureSkipVerify: true,
-		}),
-		tlscheck.WithPort(port),
-	)
-
-	info, err := checker.CheckCertificate(
-		context.Background(), ip, "localhost",
-	)
-	if err != nil {
-		t.Fatalf("unexpected error: %v", err)
-	}
-
-	if info == nil {
-		t.Fatal("expected non-nil CertificateInfo")
-	}
-
-	if info.NotAfter.IsZero() {
-		t.Error("expected non-zero NotAfter")
-	}
-
-	if info.SerialNumber == "" {
-		t.Error("expected non-empty SerialNumber")
-	}
-}
-
-func TestCheckCertificateConnectionRefused(t *testing.T) {
-	t.Parallel()
-
-	lc := &net.ListenConfig{}
-
-	ln, err := lc.Listen(
-		context.Background(), "tcp", "127.0.0.1:0",
-	)
-	if err != nil {
-		t.Fatalf("failed to listen: %v", err)
-	}
-
-	addr, ok := ln.Addr().(*net.TCPAddr)
-	if !ok {
-		t.Fatal("unexpected address type")
-	}
-
-	port := addr.Port
-
-	_ = ln.Close()
-
-	checker := tlscheck.NewStandalone(
-		tlscheck.WithTimeout(2*time.Second),
-		tlscheck.WithPort(port),
-	)
-
-	_, err = checker.CheckCertificate(
-		context.Background(), "127.0.0.1", "localhost",
-	)
-	if err == nil {
-		t.Fatal("expected error for connection refused")
-	}
-}
-
-func TestCheckCertificateContextCanceled(t *testing.T) {
-	t.Parallel()
-
-	ctx, cancel := context.WithCancel(context.Background())
-	cancel()
-
-	checker := tlscheck.NewStandalone(
-		tlscheck.WithTimeout(2*time.Second),
-		tlscheck.WithPort(1),
-	)
-
-	_, err := checker.CheckCertificate(
-		ctx, "127.0.0.1", "localhost",
-	)
-	if err == nil {
-		t.Fatal("expected error for canceled context")
-	}
-}
-
-func TestCheckCertificateTimeout(t *testing.T) {
-	t.Parallel()
-
-	checker := tlscheck.NewStandalone(
-		tlscheck.WithTimeout(1*time.Millisecond),
-		tlscheck.WithPort(1),
-	)
-
-	_, err := checker.CheckCertificate(
-		context.Background(),
-		"192.0.2.1",
-		"example.com",
-	)
-	if err == nil {
-		t.Fatal("expected error for timeout")
-	}
-}
-
-func TestCheckCertificateSANs(t *testing.T) {
-	t.Parallel()
-
-	srv, ip, port := startTLSServer(t)
-
-	defer srv.Close()
-
-	checker := tlscheck.NewStandalone(
-		tlscheck.WithTimeout(5*time.Second),
-		tlscheck.WithTLSConfig(&tls.Config{
-			//nolint:gosec // test uses self-signed cert
-			InsecureSkipVerify: true,
-		}),
-		tlscheck.WithPort(port),
-	)
-
-	info, err := checker.CheckCertificate(
-		context.Background(), ip, "localhost",
-	)
-	if err != nil {
-		t.Fatalf("unexpected error: %v", err)
-	}
-
-	if info.CommonName == "" && len(info.SubjectAlternativeNames) == 0 {
-		t.Error("expected CN or SANs to be populated")
-	}
-}

internal/watcher/interfaces.go

@@ -4,7 +4,6 @@ package watcher
 import (
 	"context"
 
-	"sneak.berlin/go/dnswatcher/internal/portcheck"
 	"sneak.berlin/go/dnswatcher/internal/tlscheck"
 )
 
@@ -37,7 +36,7 @@ type PortChecker interface {
 		ctx context.Context,
 		address string,
 		port int,
-	) (*portcheck.PortResult, error)
+	) (bool, error)
 }
 
 // TLSChecker inspects TLS certificates.

internal/watcher/watcher.go

@@ -477,7 +477,7 @@ func (w *Watcher) checkSinglePort(
 	port int,
 	hostname string,
 ) {
-	result, err := w.portCheck.CheckPort(ctx, ip, port)
+	open, err := w.portCheck.CheckPort(ctx, ip, port)
 	if err != nil {
 		w.log.Error(
 			"port check failed",
@@ -493,9 +493,9 @@ func (w *Watcher) checkSinglePort(
 	now := time.Now().UTC()
 	prev, hasPrev := w.state.GetPortState(key)
 
-	if hasPrev && !w.firstRun && prev.Open != result.Open {
+	if hasPrev && !w.firstRun && prev.Open != open {
 		stateStr := "closed"
-		if result.Open {
+		if open {
 			stateStr = "open"
 		}
 
@@ -513,7 +513,7 @@ func (w *Watcher) checkSinglePort(
 	}
 
 	w.state.SetPortState(key, &state.PortState{
-		Open:        result.Open,
+		Open:        open,
 		Hostname:    hostname,
 		LastChecked: now,
 	})

internal/watcher/watcher_test.go

@@ -9,7 +9,6 @@ import (
 	"time"
 
 	"sneak.berlin/go/dnswatcher/internal/config"
-	"sneak.berlin/go/dnswatcher/internal/portcheck"
 	"sneak.berlin/go/dnswatcher/internal/state"
 	"sneak.berlin/go/dnswatcher/internal/tlscheck"
 	"sneak.berlin/go/dnswatcher/internal/watcher"
@@ -110,20 +109,24 @@ func (m *mockPortChecker) CheckPort(
 	_ context.Context,
 	address string,
 	port int,
-) (*portcheck.PortResult, error) {
+) (bool, error) {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
 	m.calls++
 
 	if m.err != nil {
-		return nil, m.err
+		return false, m.err
 	}
 
 	key := fmt.Sprintf("%s:%d", address, port)
-	open := m.results[key]
+	open, ok := m.results[key]
 
-	return &portcheck.PortResult{Open: open}, nil
+	if !ok {
+		return false, nil
+	}
+
+	return open, nil
 }
 
 type mockTLSChecker struct {