Move around code for better clarity

pkg/util/network/cache.go

@@ -0,0 +1,45 @@
+package network
+
+import (
+	"crypto/md5"
+	"encoding/hex"
+	"io/ioutil"
+	"os"
+
+	"github.com/rancher/os/pkg/log"
+)
+
+const (
+	cacheDirectory = "/var/lib/rancher/cache/"
+)
+
+func locationHash(location string) string {
+	sum := md5.Sum([]byte(location))
+	return hex.EncodeToString(sum[:])
+}
+
+func cacheLookup(location string) []byte {
+	cacheFile := cacheDirectory + locationHash(location)
+	bytes, err := ioutil.ReadFile(cacheFile)
+	if err == nil {
+		log.Debugf("Using cached file: %s", cacheFile)
+		return bytes
+	}
+	return nil
+}
+
+func cacheAdd(location string, data []byte) {
+	tempFile, err := ioutil.TempFile(cacheDirectory, "")
+	if err != nil {
+		return
+	}
+	defer os.Remove(tempFile.Name())
+
+	_, err = tempFile.Write(data)
+	if err != nil {
+		return
+	}
+
+	cacheFile := cacheDirectory + locationHash(location)
+	os.Rename(tempFile.Name(), cacheFile)
+}