Make work source configurable for atto-safesign program

Author: codesoap

cmd/atto-safesign/config.go

@@ -10,4 +10,15 @@ var (
 	// opening an accout, but can be changed afterwards. See e.g.
 	// https://nanolooker.com/representatives to find representatives.
 	defaultRepresentative = "nano_1jtx5p8141zjtukz4msp1x93st7nh475f74odj8673qqm96xczmtcnanos1o"
+
+	// workSource specifies where the work for block submission shall
+	// come from. These options are available:
+	// - workSourceLocal: The work is generated on the CPU of the
+	//   current computer.
+	// - workSourceNode: The work is fetched from the node using the
+	//   work_generate action. Make sure that your node supports it.
+	// - workSourceLocalFallback: It is attempted to fetch the work
+	//   from the node, but if this fails, it will be generated on
+	//   the CPU of the current computer.
+	workSource = workSourceLocalFallback
 )

cmd/atto-safesign/main.go

@@ -57,6 +57,14 @@ Environment:
 	                          Authentication.
 `
 
+type workSourceType int
+
+const (
+	workSourceLocal workSourceType = iota
+	workSourceNode
+	workSourceLocalFallback
+)
+
 var accountIndexFlag uint
 var yFlag bool
 
@@ -153,7 +161,7 @@ func receive() error {
 		if err != nil {
 			return err
 		}
-		if err = block.FetchWork(node); err != nil {
+		if err = fillWork(&block, node); err != nil {
 			return err
 		}
 		blockJSON, err := json.Marshal(block)
@@ -186,7 +194,7 @@ func change() error {
 	if err != nil {
 		return err
 	}
-	if err = block.FetchWork(node); err != nil {
+	if err = fillWork(&block, node); err != nil {
 		return err
 	}
 	blockJSON, err := json.Marshal(block)
@@ -215,7 +223,7 @@ func send() error {
 	if err != nil {
 		return err
 	}
-	if err = block.FetchWork(node); err != nil {
+	if err = fillWork(&block, node); err != nil {
 		return err
 	}
 	blockJSON, err := json.Marshal(block)

cmd/atto-safesign/util.go

@@ -136,3 +136,19 @@ func letUserVerifyBlock(block atto.Block) (err error) {
 	}
 	return
 }
+
+func fillWork(block *atto.Block, node string) error {
+	switch workSource {
+	case workSourceLocal:
+		return block.GenerateWork()
+	case workSourceNode:
+		return block.FetchWork(node)
+	case workSourceLocalFallback:
+		if err := block.FetchWork(node); err != nil {
+			fmt.Fprintf(os.Stderr, "Could not fetch work from node (error: %v); generating it on CPU...\n", err)
+			return block.GenerateWork()
+		}
+		return nil
+	}
+	return fmt.Errorf("unknown work source")
+}