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path: root/vendor/go.opencensus.io/tag/validate.go
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// Copyright 2017, OpenCensus Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package tag

import "errors"

const (
    maxKeyLength = 255

    // valid are restricted to US-ASCII subset (range 0x20 (' ') to 0x7e ('~')).
    validKeyValueMin = 32
    validKeyValueMax = 126
)

var (
    errInvalidKeyName = errors.New("invalid key name: only ASCII characters accepted; max length must be 255 characters")
    errInvalidValue   = errors.New("invalid value: only ASCII characters accepted; max length must be 255 characters")
)

func checkKeyName(name string) bool {
    if len(name) == 0 {
        return false
    }
    if len(name) > maxKeyLength {
        return false
    }
    return isASCII(name)
}

func isASCII(s string) bool {
    for _, c := range s {
        if (c < validKeyValueMin) || (c > validKeyValueMax) {
            return false
        }
    }
    return true
}

func checkValue(v string) bool {
    if len(v) > maxKeyLength {
        return false
    }
    return isASCII(v)
}