fix url_encoded regex (#769)

Author: Dean Karn

regexes.go

@@ -45,7 +45,7 @@ const (
 	ethAddressRegexString            = `^0x[0-9a-fA-F]{40}$`
 	ethAddressUpperRegexString       = `^0x[0-9A-F]{40}$`
 	ethAddressLowerRegexString       = `^0x[0-9a-f]{40}$`
-	uRLEncodedRegexString            = `(%[A-Fa-f0-9]{2})`
+	uRLEncodedRegexString            = `^(?:[^%]|%[0-9A-Fa-f]{2})*$`
 	hTMLEncodedRegexString           = `&#[x]?([0-9a-fA-F]{2})|(&gt)|(&lt)|(&quot)|(&amp)+[;]?`
 	hTMLRegexString                  = `<[/]?([a-zA-Z]+).*?>`
 	splitParamsRegexString           = `'[^']*'|\S+`

validator_test.go

@@ -9537,6 +9537,9 @@ func TestURLEncodedValidation(t *testing.T) {
 		{"a%b", false},
 		{"1%2", false},
 		{"%%a%%", false},
+		{"hello", true},
+		{"", true},
+		{"+", true},
 	}
 
 	validate := New()