feat: extra protocol information (#60)

internal/probe.go

@@ -76,12 +76,13 @@ func (p Probe) Run(ctx context.Context) error {
 					p.Logger.Debug(
 						"New protocol", "count", count, "protocol", proto,
 					)
-					rhost, err := proto.Probe("")
+					rhost, extra, err := proto.Probe("")
 					report := Report{
 						ProtocolID: proto.String(),
 						Time:       time.Since(start),
 						Error:      err,
 						RHost:      rhost,
+						Extra:      extra,
 					}
 					p.Logger.Debug(
 						"Sending report back",

internal/probe_test.go

@@ -7,13 +7,14 @@ import (
 )
 
 const testHostPort = "127.0.0.1:3355"
+const testExtra = "test-extra"
 
 type testProtocol struct{}
 
 func (p *testProtocol) String() string { return "test-proto" }
 
-func (p *testProtocol) Probe(target string) (string, error) {
-	return testHostPort, nil
+func (p *testProtocol) Probe(target string) (string, string, error) {
+	return testHostPort, testExtra, nil
 }
 
 func TestProbeValidate(t *testing.T) {

internal/protocol.go

@@ -18,8 +18,10 @@ type Protocol interface {
 	String() string
 	// Attempt to check the connectivity to the target.
 	// The target depends on the protocol. For example, for HTTP it's a URL.
-	// Returns the used target or error if the attempt failed.
-	Probe(target string) (string, error)
+	// Returns the used target or error if the attempt failed. Some protocols
+	// include an additional string with extra information. For example, the
+	// HTTP protocol returns the status code.
+	Probe(target string) (string, string, error)
 }
 
 // HTTP protocol implementation.
@@ -33,26 +35,28 @@ func (h *HTTP) String() string {
 }
 
 // Probe makes an HTTP request to a random captive portal.
+//
 // The target is a URL.
-func (h *HTTP) Probe(target string) (string, error) {
+// The extra data is the status code.
+func (h *HTTP) Probe(target string) (string, string, error) {
 	cli := &http.Client{Timeout: h.Timeout}
 	url := target
 	if url == "" {
 		var err error
 		url, err = RandomCaptivePortal()
 		if err != nil {
-			return "", fmt.Errorf("selecting captive portal: %w", err)
+			return "", "", fmt.Errorf("selecting captive portal: %w", err)
 		}
 	}
 	resp, err := cli.Get(url)
 	if err != nil {
-		return "", err
+		return "", "", err
 	}
 	err = resp.Body.Close()
 	if err != nil {
-		return "", fmt.Errorf("closing response body: %w", err)
+		return "", "", fmt.Errorf("closing response body: %w", err)
 	}
-	return url, nil
+	return url, resp.Status, nil
 }
 
 // TCP protocol implementation.
@@ -66,25 +70,27 @@ func (t *TCP) String() string {
 }
 
 // Probe makes a TCP request to a random server.
+//
 // The target is a host:port.
-func (t *TCP) Probe(target string) (string, error) {
+// The extra data is the local interface.
+func (t *TCP) Probe(target string) (string, string, error) {
 	hostPort := target
 	if hostPort == "" {
 		var err error
 		hostPort, err = RandomTCPServer()
 		if err != nil {
-			return "", fmt.Errorf("selecting TCP server: %w", err)
+			return "", "", fmt.Errorf("selecting TCP server: %w", err)
 		}
 	}
 	conn, err := net.DialTimeout("tcp", hostPort, t.Timeout)
 	if err != nil {
-		return "", err
+		return "", "", err
 	}
 	err = conn.Close()
 	if err != nil {
-		return "", fmt.Errorf("closing connection: %w", err)
+		return "", "", fmt.Errorf("closing connection: %w", err)
 	}
-	return hostPort, nil
+	return hostPort, conn.LocalAddr().String(), nil
 }
 
 // DNS protocol implementation.
@@ -100,8 +106,10 @@ func (d *DNS) String() string {
 }
 
 // Probe resolves a random domain name.
+//
 // The target is a domain name.
-func (d *DNS) Probe(target string) (string, error) {
+// The extra data is the first resolved IP address.
+func (d *DNS) Probe(target string) (string, string, error) {
 	var r net.Resolver
 	ctx, cancel := context.WithTimeout(context.Background(), timeout)
 	defer cancel()
@@ -121,12 +129,12 @@ func (d *DNS) Probe(target string) (string, error) {
 		var err error
 		domain, err = RandomDomain()
 		if err != nil {
-			return "", fmt.Errorf("selecting domain: %w", err)
+			return "", "", fmt.Errorf("selecting domain: %w", err)
 		}
 	}
-	_, err := r.LookupHost(ctx, domain)
+	addrs, err := r.LookupHost(ctx, domain)
 	if err != nil {
-		return "", err
+		return "", "", err
 	}
-	return domain, nil
+	return domain, addrs[0], nil
 }

internal/protocol_test.go

@@ -20,20 +20,23 @@ func TestHTTPProbe(t *testing.T) {
 		func(t *testing.T) {
 			u := url.URL{Scheme: "http", Host: server.Addr}
 			proto := HTTP{Timeout: tout}
-			got, err := proto.Probe(u.String())
+			got, extra, err := proto.Probe(u.String())
 			if err != nil {
 				t.Fatal(err)
 			}
 			want := "http://127.0.0.1:8080"
 			if got != want {
 				t.Fatalf("got %q, want %q", got, want)
 			}
+			if extra != "200 OK" {
+				t.Fatalf("got %q, want %q", extra, "200 OK")
+			}
 		},
 	)
 	t.Run("returns an error if the request fails", func(t *testing.T) {
 		u := url.URL{Scheme: "http", Host: "localhost"}
 		proto := HTTP{Timeout: 1}
-		got, err := proto.Probe(u.String())
+		got, extra, err := proto.Probe(u.String())
 		if got != "" {
 			t.Fatalf("got %q should be zero", got)
 		}
@@ -42,6 +45,9 @@ func TestHTTPProbe(t *testing.T) {
 		if got != want {
 			t.Fatalf("got %q, want %q", got, want)
 		}
+		if extra != "" {
+			t.Fatalf("got %q should be zero", extra)
+		}
 	})
 }
 
@@ -85,18 +91,28 @@ func TestTCPProbe(t *testing.T) {
 		"returns the remote host/port if the request is successful",
 		func(t *testing.T) {
 			proto := &TCP{Timeout: tout}
-			got, err := proto.Probe(hostPort)
+			got, extra, err := proto.Probe(hostPort)
 			if err != nil {
 				t.Fatal(err)
 			}
 			if got != hostPort {
 				t.Fatalf("got %q, want %q", got, hostPort)
 			}
+			host, port, err := net.SplitHostPort(extra)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if host != "127.0.0.1" {
+				t.Fatalf("got %q, want %q", host, "127.0.0.1")
+			}
+			if port == "" {
+				t.Fatalf("got %q, want a valid port", port)
+			}
 		},
 	)
 	t.Run("returns an error if the request fails", func(t *testing.T) {
 		proto := &TCP{Timeout: 1}
-		got, err := proto.Probe("localhost:80")
+		got, extra, err := proto.Probe("localhost:80")
 		if err == nil {
 			t.Fatal("got nil, want an error")
 		}
@@ -108,6 +124,9 @@ func TestTCPProbe(t *testing.T) {
 		if got != want {
 			t.Fatalf("got %q, want %q", got, want)
 		}
+		if extra != "" {
+			t.Fatalf("got %q should be zero", extra)
+		}
 	})
 }
 
@@ -130,18 +149,21 @@ func TestDNSProbe(t *testing.T) {
 		func(t *testing.T) {
 			proto := &DNS{Timeout: tout}
 			domain := "google.com"
-			got, err := proto.Probe(domain)
+			got, extra, err := proto.Probe(domain)
 			if err != nil {
 				t.Fatal(err)
 			}
 			if got != domain {
 				t.Fatalf("got %q, want %q", got, domain)
 			}
+			if !net.ParseIP(extra).IsGlobalUnicast() {
+				t.Fatalf("got %q, want a valid IP address", extra)
+			}
 		},
 	)
 	t.Run("returns an error if the request fails", func(t *testing.T) {
 		proto := &DNS{Timeout: 1}
-		got, err := proto.Probe("invalid.aa")
+		got, extra, err := proto.Probe("invalid.aa")
 		if err == nil {
 			t.Fatal("got nil, want an error")
 		}
@@ -156,5 +178,8 @@ func TestDNSProbe(t *testing.T) {
 		if got != want {
 			t.Fatalf("got %q, want %q", got, want)
 		}
+		if extra != "" {
+			t.Fatalf("got %q should be zero", extra)
+		}
 	})
 }

internal/report.go

@@ -16,4 +16,6 @@ type Report struct {
 	Time time.Duration `json:"time"`
 	// Network error.
 	Error error `json:"error,omitempty"`
+	// Extra information. Depends on the protocol.
+	Extra string `json:"extra,omitempty"`
 }

main.go

@@ -132,23 +132,23 @@ func main() {
 	}
 }
 
-// Fatal logs the error to the standard output and exits with status 1.
+// Logs the error to the standard output and exits with status 1.
 func fatal(err error) {
 	fmt.Fprintf(os.Stderr, "%s: %s\n", appName, err)
 	os.Exit(1)
 }
 
-// ReportToLine returns a human-readable representation of the report.
+// Returns a human-readable representation of the report.
 func reportToLine(r *internal.Report) string {
-	symbol := green("✔")
-	suffix := r.RHost
+	line := fmt.Sprintf("%-15s %-14s %s", bold(r.ProtocolID), r.Time, r.RHost)
+	suffix := r.Extra
+	prefix := green("✔")
 	if r.Error != nil {
-		symbol = red("✘")
+		prefix = red("✘")
 		suffix = r.Error.Error()
 	}
-	return fmt.Sprintf("%s %s", symbol, fmt.Sprintf(
-		"%-15s %-14s %-15s", bold(r.ProtocolID), r.Time, faint(suffix),
-	))
+	suffix = fmt.Sprintf("(%s)", suffix)
+	return fmt.Sprintf("%s %s %s", prefix, line, faint(suffix))
 }
 
 var (