Break out cmd/yggdrasil a bit, tweaks

cmd/yggdrasil/config.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"bytes"
+	"io/ioutil"
+	"os"
+
+	"github.com/yggdrasil-network/yggdrasil-go/src/config"
+)
+
+func readConfig(useconf *bool, useconffile *string, normaliseconf *bool) *config.NodeConfig {
+	// Use a configuration file. If -useconf, the configuration will be read
+	// from stdin. If -useconffile, the configuration will be read from the
+	// filesystem.
+	var conf []byte
+	var err error
+	if *useconffile != "" {
+		// Read the file from the filesystem
+		conf, err = ioutil.ReadFile(*useconffile)
+	} else {
+		// Read the file from stdin.
+		conf, err = ioutil.ReadAll(os.Stdin)
+	}
+	if err != nil {
+		panic(err)
+	}
+	// If there's a byte order mark - which Windows 10 is now incredibly fond of
+	// throwing everywhere when it's converting things into UTF-16 for the hell
+	// of it - remove it and decode back down into UTF-8. This is necessary
+	// because hjson doesn't know what to do with UTF-16 and will panic
+	if bytes.Compare(conf[0:2], []byte{0xFF, 0xFE}) == 0 ||
+		bytes.Compare(conf[0:2], []byte{0xFE, 0xFF}) == 0 {
+		utf := unicode.UTF16(unicode.BigEndian, unicode.UseBOM)
+		decoder := utf.NewDecoder()
+		conf, err = decoder.Bytes(conf)
+		if err != nil {
+			panic(err)
+		}
+	}
+	// Generate blank configuration
+	cfg := config.GenerateConfig()
+	// ... and then update it with the supplied HJSON input
+	if err := cfg.UnmarshalHJSON(conf); err != nil {
+		panic(err)
+	}
+	return cfg
+}