httpserver: Implement {sever_port} placeholder (#2424)

caddyhttp/httpserver/replacer.go

@@ -506,6 +506,16 @@ func (r *replacer) getSubstitution(key string) string {
 			return cert.NotBefore.Format("Jan 02 15:04:05 2006 MST")
 		}
 		return r.emptyValue
+	case "{server_port}":
+		_, port, err := net.SplitHostPort(r.request.Host)
+		if err != nil {
+			if r.request.TLS != nil {
+				return "443"
+			} else {
+				return "80"
+			}
+		}
+		return port
 	default:
 		// {labelN}
 		if strings.HasPrefix(key, "{label") {

caddyhttp/httpserver/replacer_test.go

@@ -127,6 +127,7 @@ func TestReplace(t *testing.T) {
 		{"{label1} {label2} {label3} {label4}", "localhost local - -"},
 		{"Label with missing number is {label} or {labelQQ}", "Label with missing number is - or -"},
 		{"\\{ 'hostname': '{hostname}' \\}", "{ 'hostname': '" + hostname + "' }"},
+		{"{server_port}", "80"},
 	}
 
 	for _, c := range testCases {
@@ -159,6 +160,33 @@ func TestReplace(t *testing.T) {
 	}
 }
 
+func TestCustomServerPort(t *testing.T) {
+	w := httptest.NewRecorder()
+	recordRequest := NewResponseRecorder(w)
+	reader := strings.NewReader(`{"username": "dennis"}`)
+
+	request, err := http.NewRequest("POST", "http://localhost.local:8000/?foo=bar", reader)
+	if err != nil {
+		t.Fatalf("Failed to make request: %v", err)
+	}
+	ctx := context.WithValue(request.Context(), OriginalURLCtxKey, *request.URL)
+	request = request.WithContext(ctx)
+
+	repl := NewReplacer(request, recordRequest, "-")
+
+	testCase := struct {
+		template string
+		expect   string
+	}{
+		template: "{server_port}",
+		expect:   "8000",
+	}
+
+	if expected, actual := testCase.expect, repl.Replace(testCase.template); expected != actual {
+		t.Errorf("for template '%s', expected '%s', got '%s'", testCase.template, expected, actual)
+	}
+}
+
 func TestTlsReplace(t *testing.T) {
 	w := httptest.NewRecorder()
 	recordRequest := NewResponseRecorder(w)
@@ -246,6 +274,7 @@ eqp31wM9il1n+guTNyxJd+FzVAH+hCZE5K+tCgVDdVFUlDEHHbS/wqb2PSIoouLV
 		{"{tls_client_v_end}", cVEnd},
 		{"{tls_client_v_remain}", cVRemain},
 		{"{tls_client_v_start}", cVStart},
+		{"{server_port}", "443"},
 	}
 
 	for _, c := range testCases {