validate and normalize relay urls received from kind 3 and 10002.

utils.go

@@ -1,6 +1,7 @@
 package nostr
 
 import (
+	"net/url"
 	"strings"
 
 	"golang.org/x/exp/constraints"
@@ -129,3 +130,17 @@ func InsertEventIntoDescendingList(sortedArray []*Event, event *Event) []*Event
 
 	return sortedArray
 }
+
+func IsValidRelayURL(u string) bool {
+	parsed, err := url.Parse(u)
+	if err != nil {
+		return false
+	}
+	if parsed.Scheme != "wss" && parsed.Scheme != "ws" {
+		return false
+	}
+	if len(strings.Split(parsed.Host, ".")) < 2 {
+		return false
+	}
+	return true
+}