If scheme and port defy convention, it is an error

This prevents serving HTTPS over port 80 or HTTP over 443. It's confusing and we don't allow it.

caddy/parse/parsing.go

@@ -338,7 +338,12 @@ func standardAddress(str string) (address, error) {
 
 	// repeated or conflicting scheme is confusing, so error
 	if scheme != "" && (port == "http" || port == "https") {
-		return address{}, fmt.Errorf("[%s] scheme specified twice in address", str)
+		return address{}, fmt.Errorf("[%s] scheme specified twice in address", input)
+	}
+
+	// error if scheme and port combination violate convention
+	if (scheme == "http" && port == "443") || (scheme == "https" && port == "80") {
+		return address{}, fmt.Errorf("[%s] scheme and port violate convention", input)
 	}
 
 	// standardize http and https ports to their respective port numbers

caddy/parse/parsing_test.go

@@ -27,6 +27,8 @@ func TestStandardAddress(t *testing.T) {
 		{`:https`, "https", "", "443", false},
 		{`http://localhost:https`, "", "", "", true}, // conflict
 		{`http://localhost:http`, "", "", "", true},  // repeated scheme
+		{`http://localhost:443`, "", "", "", true},   // not conventional
+		{`https://localhost:80`, "", "", "", true},   // not conventional
 		{`http://localhost`, "http", "localhost", "80", false},
 		{`https://localhost`, "https", "localhost", "443", false},
 		{`http://127.0.0.1`, "http", "127.0.0.1", "80", false},