Prevent minio server starting in standalone erasure mode for wrong inputs. (#4700)

It is possible at times due to a typo when distributed mode was intended
a user might end up starting standalone erasure mode causing confusion.
Add code to check this based on some standard heuristic guess work and
report an error to the user.

Fixes #4686

cmd/endpoint.go

@@ -132,6 +132,12 @@ func NewEndpoint(arg string) (ep Endpoint, e error) {
 			return ep, err
 		}
 	} else {
+		// Only check if the arg is an ip address and ask for scheme since its absent.
+		// localhost, example.com, any FQDN cannot be disambiguated from a regular file path such as
+		// /mnt/export1. So we go ahead and start the minio server in FS modes in these cases.
+		if isHostIPv4(arg) {
+			return ep, fmt.Errorf("invalid URL endpoint format: missing scheme http or https")
+		}
 		u = &url.URL{Path: path.Clean(arg)}
 		isLocal = true
 	}
@@ -212,7 +218,6 @@ func NewEndpointList(args ...string) (endpoints EndpointList, err error) {
 			return nil, fmt.Errorf("duplicate endpoints found")
 		}
 		uniqueArgs.Add(arg)
-
 		endpoints = append(endpoints, endpoint)
 	}
 
@@ -267,6 +272,7 @@ func CreateEndpoints(serverAddr string, args ...string) (string, EndpointList, S
 	localEndpointCount := 0
 	localServerAddrSet := set.NewStringSet()
 	localPortSet := set.NewStringSet()
+
 	for _, endpoint := range endpoints {
 		endpointPathSet.Add(endpoint.Path)
 		if endpoint.IsLocal {

cmd/endpoint_test.go

@@ -70,6 +70,7 @@ func TestNewEndpoint(t *testing.T) {
 		{"http://server:8080//", Endpoint{}, -1, fmt.Errorf("empty or root path is not supported in URL endpoint")},
 		{"http://server:8080/", Endpoint{}, -1, fmt.Errorf("empty or root path is not supported in URL endpoint")},
 		{"http://server/path", Endpoint{}, -1, fmt.Errorf("lookup server" + errMsg)},
+		{"192.168.1.210:9000", Endpoint{}, -1, fmt.Errorf("invalid URL endpoint format: missing scheme http or https")},
 	}
 
 	for _, testCase := range testCases {
@@ -122,6 +123,7 @@ func TestNewEndpointList(t *testing.T) {
 		{[]string{"ftp://server/d1", "http://server/d2", "http://server/d3", "http://server/d4"}, fmt.Errorf("'ftp://server/d1': invalid URL endpoint format")},
 		{[]string{"d1", "http://localhost/d2", "d3", "d4"}, fmt.Errorf("mixed style endpoints are not supported")},
 		{[]string{"http://example.org/d1", "https://example.com/d1", "http://example.net/d1", "https://example.edut/d1"}, fmt.Errorf("mixed scheme is not supported")},
+		{[]string{"192.168.1.210:9000/tmp/dir0", "192.168.1.210:9000/tmp/dir1", "192.168.1.210:9000/tmp/dir2", "192.168.110:9000/tmp/dir3"}, fmt.Errorf("'192.168.1.210:9000/tmp/dir0': invalid URL endpoint format: missing scheme http or https")},
 	}
 
 	for _, testCase := range testCases {

cmd/net.go

@@ -153,6 +153,15 @@ func getAPIEndpoints(serverAddr string) (apiEndpoints []string) {
 	return apiEndpoints
 }
 
+// isHostIPv4 - helper for validating if the provided arg is an ip address.
+func isHostIPv4(ipAddress string) bool {
+	host, _, err := net.SplitHostPort(ipAddress)
+	if err != nil {
+		host = ipAddress
+	}
+	return net.ParseIP(host) != nil
+}
+
 // checkPortAvailability - check if given port is already in use.
 // Note: The check method tries to listen on given port and closes it.
 // It is possible to have a disconnected client in this tiny window of time.

cmd/net_test.go

@@ -317,3 +317,23 @@ func TestSameLocalAddrs(t *testing.T) {
 		}
 	}
 }
+func TestIsHostIPv4(t *testing.T) {
+	testCases := []struct {
+		args           string
+		expectedResult bool
+	}{
+		{"localhost", false},
+		{"localhost:9000", false},
+		{"example.com", false},
+		{"http://192.168.1.0", false},
+		{"http://192.168.1.0:9000", false},
+		{"192.168.1.0", true},
+	}
+
+	for _, testCase := range testCases {
+		ret := isHostIPv4(testCase.args)
+		if testCase.expectedResult != ret {
+			t.Fatalf("expected: %v , got: %v", testCase.expectedResult, ret)
+		}
+	}
+}