vendor/go.opencensus.io/tag/validate.go

   1 // Copyright 2017, OpenCensus Authors
   2 //
   3 // Licensed under the Apache License, Version 2.0 (the "License");
   4 // you may not use this file except in compliance with the License.
   5 // You may obtain a copy of the License at
   6 //
   7 //     http://www.apache.org/licenses/LICENSE-2.0
   8 //
   9 // Unless required by applicable law or agreed to in writing, software
  10 // distributed under the License is distributed on an "AS IS" BASIS,
  11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 // See the License for the specific language governing permissions and
  13 // limitations under the License.
  14
  15 package tag
  16
  17 import "errors"
  18
  19 const (
  20         maxKeyLength = 255
  21
  22         // valid are restricted to US-ASCII subset (range 0x20 (' ') to 0x7e ('~')).
  23         validKeyValueMin = 32
  24         validKeyValueMax = 126
  25 )
  26
  27 var (
  28         errInvalidKeyName = errors.New("invalid key name: only ASCII characters accepted; max length must be 255 characters")
  29         errInvalidValue   = errors.New("invalid value: only ASCII characters accepted; max length must be 255 characters")
  30 )
  31
  32 func checkKeyName(name string) bool {
  33         if len(name) == 0 {
  34                 return false
  35         }
  36         if len(name) > maxKeyLength {
  37                 return false
  38         }
  39         return isASCII(name)
  40 }
  41
  42 func isASCII(s string) bool {
  43         for _, c := range s {
  44                 if (c < validKeyValueMin) || (c > validKeyValueMax) {
  45                         return false
  46                 }
  47         }
  48         return true
  49 }
  50
  51 func checkValue(v string) bool {
  52         if len(v) > maxKeyLength {
  53                 return false
  54         }
  55         return isASCII(v)
  56 }