Moved server packages to a separate folder

server/middleware/IPToHost.go

@@ -0,0 +1,43 @@
+package middleware
+
+import (
+	"net"
+	"time"
+
+	"github.com/akyoto/cache"
+)
+
+var ipToHosts = cache.New(60 * time.Minute)
+
+// GetHostsForIP returns all host names for the given IP (if cached).
+func GetHostsForIP(ip string) ([]string, bool) {
+	hosts, found := ipToHosts.Get(ip)
+
+	if !found {
+		hosts = findHostsForIP(ip)
+	}
+
+	if hosts == nil {
+		return nil, found
+	}
+
+	return hosts.([]string), found
+}
+
+// Finds all host names for the given IP
+func findHostsForIP(ip string) []string {
+	hosts, err := net.LookupAddr(ip)
+
+	if err != nil {
+		return nil
+	}
+
+	if len(hosts) == 0 {
+		return nil
+	}
+
+	// Cache host names
+	ipToHosts.Set(ip, hosts, 60*time.Minute)
+
+	return hosts
+}