Code hygiene

- Minor performance improve for FQDN validation
- Fix typo in documentation
- Simplified hostname regex

baked_in.go

@@ -1491,6 +1491,6 @@ func isFQDN(fl FieldLevel) bool {
 		val = val[0 : len(val)-1]
 	}
 
-	return hostnameRegex.MatchString(val) &&
+	return (strings.IndexAny(val, ".") > -1) &&
-		(strings.IndexAny(val, ".") > -1)
+		hostnameRegex.MatchString(val)
 }

doc.go

@@ -796,7 +796,7 @@ Note: See Go's ParseMAC for accepted formats and types:
 
 Hostname
 
-This validates that a stringa value is a valid Hostname
+This validates that a string value is a valid Hostname
 
 	Usage: hostname
 

regexes.go

@@ -30,7 +30,7 @@ const (
 	latitudeRegexString            = "^[-+]?([1-8]?\\d(\\.\\d+)?|90(\\.0+)?)$"
 	longitudeRegexString           = "^[-+]?(180(\\.0+)?|((1[0-7]\\d)|([1-9]?\\d))(\\.\\d+)?)$"
 	sSNRegexString                 = `^\d{3}[- ]?\d{2}[- ]?\d{4}$`
-	hostnameRegexString            = `^(([a-zA-Z]|[a-zA-Z][a-zA-Z0-9\-]*[a-zA-Z0-9])\.)*([A-Za-z]|[A-Za-z][A-Za-z0-9\-]*[A-Za-z0-9])$`
+	hostnameRegexString            = `^[a-zA-Z][a-zA-Z0-9\-\.]+[a-z-Az0-9]$`
 )
 
 var (