Valid hostname check

Signed-off-by: Simon Thulbourn <simon+github@thulbourn.com>

host.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"net"
@@ -16,8 +17,9 @@ import (
 )
 
 var (
-	validHostNameChars   = `[a-zA-Z0-9_]`
+	validHostNameChars   = `[a-zA-Z0-9\-\.]`
 	validHostNamePattern = regexp.MustCompile(`^` + validHostNameChars + `+$`)
+	ErrInvalidHostname   = errors.New("Invalid hostname specified")
 )
 
 type Host struct {
@@ -78,7 +80,7 @@ func LoadHost(name string, storePath string) (*Host, error) {
 
 func ValidateHostName(name string) (string, error) {
 	if !validHostNamePattern.MatchString(name) {
-		return name, fmt.Errorf("Invalid host name %q, it must match %s", name, validHostNamePattern)
+		return name, ErrInvalidHostname
 	}
 	return name, nil
 }
@@ -262,6 +264,11 @@ DOCKER_TLS=no`, opts, machineCaCertPath, machineServerCertPath, machineServerKey
 }
 
 func (h *Host) Create(name string) error {
+	name, err := ValidateHostName(name)
+	if err != nil {
+		return err
+	}
+
 	if err := h.Driver.Create(); err != nil {
 		return err
 	}

host_test.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"testing"
+)
+
+func TestValidateHostnameValid(t *testing.T) {
+	hosts := []string{
+		"zomg",
+		"test-ing",
+		"some.h0st",
+	}
+
+	for _, v := range hosts {
+		h, err := ValidateHostName(v)
+		if err != nil {
+			t.Fatal("Invalid hostname")
+		}
+
+		if h != v {
+			t.Fatal("Hostname doesn't match")
+		}
+	}
+}
+
+func TestValidateHostnameInvalid(t *testing.T) {
+	hosts := []string{
+		"zom_g",
+		"test$ing",
+		"some😄host",
+	}
+
+	for _, v := range hosts {
+		_, err := ValidateHostName(v)
+		if err == nil {
+			t.Fatal("No error returned")
+		}
+	}
+}