Check for duplicate status code entries in 'errors' directive

caddyhttp/errors/setup.go

@@ -123,12 +123,20 @@ func errorsParse(c *caddy.Controller) (*ErrorHandler, error) {
 				f.Close()
 
 				if what == "*" {
+					if handler.GenericErrorPage != "" {
+						return hadBlock, c.Errf("Duplicate status code entry: %s", what)
+					}
 					handler.GenericErrorPage = where
 				} else {
 					whatInt, err := strconv.Atoi(what)
 					if err != nil {
 						return hadBlock, c.Err("Expecting a numeric status code or '*', got '" + what + "'")
 					}
+
+					if _, exists := handler.ErrorPages[whatInt]; exists {
+						return hadBlock, c.Errf("Duplicate status code entry: %s", what)
+					}
+
 					handler.ErrorPages[whatInt] = where
 				}
 			}

caddyhttp/errors/setup_test.go

@@ -115,6 +115,15 @@ func TestErrorsParse(t *testing.T) {
 				503: "503.html",
 			},
 		}},
+		// Next two test cases is the detection of duplicate status codes
+		{`errors {
+        503 503.html
+        503 503.html
+}`, true, ErrorHandler{}},
+		{`errors {
+        * generic_error.html
+        * generic_error.html
+}`, true, ErrorHandler{}},
 	}
 	for i, test := range tests {
 		actualErrorsRule, err := errorsParse(caddy.NewTestController("http", test.inputErrorsRules))
@@ -123,6 +132,8 @@ func TestErrorsParse(t *testing.T) {
 			t.Errorf("Test %d didn't error, but it should have", i)
 		} else if err != nil && !test.shouldErr {
 			t.Errorf("Test %d errored, but it shouldn't have; got '%v'", i, err)
+		} else {
+			continue
 		}
 		if actualErrorsRule.LogFile != test.expectedErrorHandler.LogFile {
 			t.Errorf("Test %d expected LogFile to be %s, but got %s",