revert hostname validator

Author: casualjim

default.go

@@ -19,13 +19,34 @@ import (
 	"encoding/base64"
 	"fmt"
 	"regexp"
+	"strings"
 
 	"github.com/asaskevich/govalidator"
 	"github.com/mailru/easyjson/jlexer"
 	"github.com/mailru/easyjson/jwriter"
 )
 
 const (
+	// HostnamePattern http://json-schema.org/latest/json-schema-validation.html#anchor114
+	//  A string instance is valid against this attribute if it is a valid
+	//  representation for an Internet host name, as defined by RFC 1034, section 3.1 [RFC1034].
+	//  http://tools.ietf.org/html/rfc1034#section-3.5
+	//  <digit> ::= any one of the ten digits 0 through 9
+	//  var digit = /[0-9]/;
+	//  <letter> ::= any one of the 52 alphabetic characters A through Z in upper case and a through z in lower case
+	//  var letter = /[a-zA-Z]/;
+	//  <let-dig> ::= <letter> | <digit>
+	//  var letDig = /[0-9a-zA-Z]/;
+	//  <let-dig-hyp> ::= <let-dig> | "-"
+	//  var letDigHyp = /[-0-9a-zA-Z]/;
+	//  <ldh-str> ::= <let-dig-hyp> | <let-dig-hyp> <ldh-str>
+	//  var ldhStr = /[-0-9a-zA-Z]+/;
+	//  <label> ::= <letter> [ [ <ldh-str> ] <let-dig> ]
+	//  var label = /[a-zA-Z](([-0-9a-zA-Z]+)?[0-9a-zA-Z])?/;
+	//  <subdomain> ::= <label> | <subdomain> "." <label>
+	//  var subdomain = /^[a-zA-Z](([-0-9a-zA-Z]+)?[0-9a-zA-Z])?(\.[a-zA-Z](([-0-9a-zA-Z]+)?[0-9a-zA-Z])?)*$/;
+	//  <domain> ::= <subdomain> | " "
+	HostnamePattern = `^[a-zA-Z](([-0-9a-zA-Z]+)?[0-9a-zA-Z])?(\.[a-zA-Z](([-0-9a-zA-Z]+)?[0-9a-zA-Z])?)*$`
 	// UUIDPattern Regex for UUID that allows uppercase
 	UUIDPattern = `(?i)^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$`
 	// UUID3Pattern Regex for UUID3 that allows uppercase
@@ -37,12 +58,35 @@ const (
 )
 
 var (
-	rxUUID  = regexp.MustCompile(UUIDPattern)
-	rxUUID3 = regexp.MustCompile(UUID3Pattern)
-	rxUUID4 = regexp.MustCompile(UUID4Pattern)
-	rxUUID5 = regexp.MustCompile(UUID5Pattern)
+	rxHostname = regexp.MustCompile(HostnamePattern)
+	rxUUID     = regexp.MustCompile(UUIDPattern)
+	rxUUID3    = regexp.MustCompile(UUID3Pattern)
+	rxUUID4    = regexp.MustCompile(UUID4Pattern)
+	rxUUID5    = regexp.MustCompile(UUID5Pattern)
 )
 
+// IsHostname returns true when the string is a valid hostname
+func IsHostname(str string) bool {
+	if !rxHostname.MatchString(str) {
+		return false
+	}
+
+	// the sum of all label octets and label lengths is limited to 255.
+	if len(str) > 255 {
+		return false
+	}
+
+	// Each node has a label, which is zero to 63 octets in length
+	parts := strings.Split(str, ".")
+	valid := true
+	for _, p := range parts {
+		if len(p) > 63 {
+			valid = false
+		}
+	}
+	return valid
+}
+
 // IsUUID returns true is the string matches a UUID, upper case is allowed
 func IsUUID(str string) bool {
 	return rxUUID.MatchString(str)
@@ -71,7 +115,7 @@ func init() {
 	Default.Add("email", &eml, govalidator.IsEmail)
 
 	hn := Hostname("")
-	Default.Add("hostname", &hn, govalidator.IsDNSName)
+	Default.Add("hostname", &hn, IsHostname)
 
 	ip4 := IPv4("")
 	Default.Add("ipv4", &ip4, govalidator.IsIPv4)