[MM-14333] Stricten external HTTP Calls to require that own IPs need to be explicitly whitelisted (#10375)

* Stricten external HTTP Calls to require that own IPs need to be explicitly whitelisted

* gofmt

* Documentation; Style fixes for IsOwnIP function

services/httpservice/httpservice.go

@@ -67,12 +67,24 @@ func (h *HTTPServiceImpl) MakeTransport(trustURLs bool) http.RoundTripper {
 	}
 
 	allowIP := func(ip net.IP) bool {
-		if !IsReservedIP(ip) {
+		reservedIP := IsReservedIP(ip)
+		ownIP, err := IsOwnIP(ip)
+
+		// If there is an error getting the self-assigned IPs, default to the secure option
+		if err != nil {
+			return false
+		}
+
+		// If it's not a reserved IP and it's not self-assigned IP, accept the IP
+		if !reservedIP && !ownIP {
 			return true
 		}
+
 		if h.configService.Config().ServiceSettings.AllowedUntrustedInternalConnections == nil {
 			return false
 		}
+
+		// In the case it's the self-assigned IP, enforce that it needs to be explicitly added to the AllowedUntrustedInternalConnections
 		for _, allowed := range strings.Fields(*h.configService.Config().ServiceSettings.AllowedUntrustedInternalConnections) {
 			if _, ipRange, err := net.ParseCIDR(allowed); err == nil && ipRange.Contains(ip) {
 				return true