From c7212b438dfabb2b28b8677bd07dfd01b92dc969 Mon Sep 17 00:00:00 2001
From: Anthony Romano <anthony.romano@coreos.com>
Date: Mon, 12 Sep 2016 19:49:22 -0700
Subject: [PATCH] embed: warn on domain name in listener

---
 embed/config.go | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/embed/config.go b/embed/config.go
index 94e95902c1d..31a4ce987ef 100644
--- a/embed/config.go
+++ b/embed/config.go
@@ -17,6 +17,7 @@ package embed
 import (
 	"fmt"
 	"io/ioutil"
+	"net"
 	"net/http"
 	"net/url"
 	"strings"
@@ -253,6 +254,13 @@ func (cfg *configYAML) configFromFile(path string) error {
 }
 
 func (cfg *Config) Validate() error {
+	if err := checkBindURLs(cfg.LPUrls); err != nil {
+		return err
+	}
+	if err := checkBindURLs(cfg.LCUrls); err != nil {
+		return err
+	}
+
 	// Check if conflicting flags are passed.
 	nSet := 0
 	for _, v := range []bool{cfg.Durl != "", cfg.InitialCluster != "", cfg.DNSCluster != ""} {
@@ -346,3 +354,27 @@ func (cfg Config) IsDefaultHost() (string, error) {
 	}
 	return "", defaultHostStatus
 }
+
+// checkBindURLs returns an error if any URL uses a domain name.
+// TODO: return error in 3.2.0
+func checkBindURLs(urls []url.URL) error {
+	for _, url := range urls {
+		if url.Scheme == "unix" || url.Scheme == "unixs" {
+			continue
+		}
+		host, _, err := net.SplitHostPort(url.Host)
+		if err != nil {
+			return err
+		}
+		if host == "localhost" {
+			// special case for local address
+			// TODO: support /etc/hosts ?
+			continue
+		}
+		if net.ParseIP(host) == nil {
+			err := fmt.Errorf("expected IP in URL for binding (%s)", url.String())
+			plog.Warning(err)
+		}
+	}
+	return nil
+}