Add LongPollWait command (#8)

Author: johnmaguire

client.go

@@ -168,6 +168,28 @@ func (c *Client) CheckForUpdate(ctx context.Context, creds Credentials) (bool, e
 	return result.Data.UpdateAvailable, nil
 }
 
+// LongPollWait sends a signed message to a DNClient API endpoint that will block, returning only
+// if there is an action the client should take before the timeout (config updates, debug commands)
+func (c *Client) LongPollWait(ctx context.Context, creds Credentials, supportedActions []string) (string, error) {
+	value, err := json.Marshal(message.LongPollWaitRequest{
+		SupportedActions: supportedActions,
+	})
+	if err != nil {
+		return "", fmt.Errorf("failed to marshal DNClient message: %s", err)
+	}
+
+	respBody, err := c.postDNClient(ctx, message.LongPollWait, value, creds.HostID, creds.Counter, creds.PrivateKey)
+	if err != nil {
+		return "", fmt.Errorf("failed to post message to dnclient api: %w", err)
+	}
+	result := message.LongPollWaitResponseWrapper{}
+	err = json.Unmarshal(respBody, &result)
+	if err != nil {
+		return "", fmt.Errorf("failed to interpret API response: %s", err)
+	}
+	return result.Data.Action, nil
+}
+
 func (c *Client) DoUpdateWithTimeout(ctx context.Context, t time.Duration, creds Credentials) ([]byte, []byte, *Credentials, error) {
 	toCtx, cancel := context.WithTimeout(ctx, t)
 	defer cancel()

dnapitest/dnapitest.go

@@ -155,7 +155,8 @@ func (s *Server) handlerDNClient(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if msg.Type == message.DoUpdate {
+	switch msg.Type {
+	case message.DoUpdate:
 		var updateKeys message.DoUpdateRequest
 		err = json.Unmarshal(msg.Value, &updateKeys)
 		if err != nil {
@@ -169,6 +170,20 @@ func (s *Server) handlerDNClient(w http.ResponseWriter, r *http.Request) {
 			http.Error(w, err.Error(), http.StatusInternalServerError)
 			return
 		}
+	case message.LongPollWait:
+		var longPoll message.LongPollWaitRequest
+		err = json.Unmarshal(msg.Value, &longPoll)
+		if err != nil {
+			s.errors = append(s.errors, fmt.Errorf("failed to unmarshal LongPollWaitRequest: %w", err))
+			http.Error(w, "failed to unmarshal LongPollWaitRequest", http.StatusInternalServerError)
+			return
+		}
+
+		if len(longPoll.SupportedActions) == 0 {
+			s.errors = append(s.errors, fmt.Errorf("no supported actions"))
+			http.Error(w, "no supported actions", http.StatusInternalServerError)
+			return
+		}
 	}
 
 	// return the associated response

message/message.go

@@ -10,6 +10,7 @@ import (
 const (
 	CheckForUpdate = "CheckForUpdate"
 	DoUpdate       = "DoUpdate"
+	LongPollWait   = "LongPollWait"
 )
 
 // EndpointV1 is the version 1 DNClient API endpoint.
@@ -73,6 +74,28 @@ type DoUpdateResponse struct {
 	TrustedKeys []byte `json:"trustedKeys"`
 }
 
+// LongPollWaitResponseWrapper contains a response to LongPollWawit inside "data."
+type LongPollWaitResponseWrapper struct {
+	Data LongPollWaitResponse `json:"data"`
+}
+
+// LongPollWaitRequest is the request message associated with a LongPollWait call.
+type LongPollWaitRequest struct {
+	SupportedActions []string `json:"supportedActions"`
+}
+
+// DNClientLongPollResponse is the response message associated with a LongPollWait call.
+type LongPollWaitResponse struct {
+	Action string `json:"action"` // e.g. NoOp, StreamLogs, DoUpdate
+}
+
+type ClientInfo struct {
+	Identifier   string `json:"identifier"`
+	Version      string `json:"version"`
+	OS           string `json:"os"`
+	Architecture string `json:"architecture"`
+}
+
 // EnrollEndpoint is the REST enrollment endpoint.
 const EnrollEndpoint = "/v2/enroll"