Allow command callers to specify Command UUID for idempotency (#754)

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## [Unreleased](https://github.com/micromdm/micromdm/compare/v1.8.0...main) TBD
 
 - Fix SetFirmwarePassword and VerifyFirmwarePassword parameters (#743)
+- Command UUID can now be passed in as as a request parameter (#754)
 
 ## [v1.8.0](https://github.com/micromdm/micromdm/compare/v1.7.1...v1.8.0) February, 2021
 

mdm/mdm/command.go

@@ -1,12 +1,15 @@
 package mdm
 
 import (
+	"strings"
+
 	"github.com/google/uuid"
 	"github.com/micromdm/micromdm/mdm/appmanifest"
 )
 
 type CommandRequest struct {
-	UDID string `json:"udid"`
+	UDID        string `json:"udid"`
+	CommandUUID string `json:"command_uuid"`
 	*Command
 }
 
@@ -17,9 +20,12 @@ type CommandPayload struct {
 
 func NewCommandPayload(request *CommandRequest) (*CommandPayload, error) {
 	payload := &CommandPayload{
-		CommandUUID: uuid.New().String(),
+		CommandUUID: request.CommandUUID,
 		Command:     request.Command,
 	}
+	if strings.TrimSpace(payload.CommandUUID) == "" {
+		payload.CommandUUID = uuid.New().String()
+	}
 	return payload, nil
 }
 

mdm/mdm/mdm_command_test.go

@@ -133,6 +133,49 @@ func TestUnmarshalCommandPayload(t *testing.T) {
 		})
 	}
 }
+func TestNewCommandPayload(t *testing.T) {
+	// Unit test cases for request params
+	var tests = []struct {
+		name    string
+		request CommandRequest
+		testFn  func(t *testing.T, payload *CommandPayload)
+	}{
+		{
+			name:    "Uses UUID passed to CommandRequest",
+			request: CommandRequest{CommandUUID: "this-uuid-should-be-used"},
+			testFn: func(t *testing.T, payload *CommandPayload) {
+				if payload.CommandUUID != "this-uuid-should-be-used" {
+					t.Error("CommandUUID is not set to CommandRequest.CommandUUID")
+				}
+			},
+		},
+		{
+			name:    "Defaults to generated UUID if CommandUUID is an empty string",
+			request: CommandRequest{CommandUUID: ""},
+			testFn: func(t *testing.T, payload *CommandPayload) {
+				if payload.CommandUUID == "" {
+					t.Error("CommandUUID should be a generated UUID")
+				}
+			},
+		},
+		{
+			name:    "Defaults to generated UUID if CommandUUID is all whitespace",
+			request: CommandRequest{CommandUUID: " "},
+			testFn: func(t *testing.T, payload *CommandPayload) {
+				if payload.CommandUUID == " " {
+					t.Error("CommandUUID should be a generated UUID")
+				}
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var payload, _ = NewCommandPayload(&tt.request)
+			tt.testFn(t, payload)
+		})
+	}
+}
 
 func mustLoadFile(t *testing.T, filename string) []byte {
 	t.Helper()

mdm/mdm/unmarshal_json.go

@@ -11,12 +11,14 @@ func (c *CommandRequest) UnmarshalJSON(data []byte) error {
 	var request = struct {
 		UDID        string `json:"udid"`
 		RequestType string `json:"request_type"`
+		CommandUUID string `json:"command_uuid"`
 	}{}
 	if err := json.Unmarshal(data, &request); err != nil {
 		return errors.Wrap(err, "mdm: unmarshal json command request")
 	}
 	c.UDID = request.UDID
 	c.Command = &Command{}
+	c.CommandUUID = request.CommandUUID
 	return c.Command.UnmarshalJSON(data)
 }