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// Copyright 2020 New Relic Corporation. All rights reserved.
// SPDX-License-Identifier: Apache-2.0
package utilization
import (
"fmt"
"strings"
"time"
)
// Helper constants, functions, and types common to multiple providers are
// contained in this file.
// Constants from the spec.
const (
maxFieldValueSize = 255 // The maximum value size, in bytes.
providerTimeout = 500 * time.Millisecond // The maximum time a HTTP provider may block.
lookupAddrTimeout = 500 * time.Millisecond
)
type validationError struct{ e error }
func (a validationError) Error() string {
return a.e.Error()
}
func isValidationError(e error) bool {
_, is := e.(validationError)
return is
}
// This function normalises string values per the utilization spec.
func normalizeValue(s string) (string, error) {
out := strings.TrimSpace(s)
bytes := []byte(out)
if len(bytes) > maxFieldValueSize {
return "", validationError{fmt.Errorf("response is too long: got %d; expected <=%d", len(bytes), maxFieldValueSize)}
}
for i, r := range out {
if !isAcceptableRune(r) {
return "", validationError{fmt.Errorf("bad character %x at position %d in response", r, i)}
}
}
return out, nil
}
func isAcceptableRune(r rune) bool {
switch r {
case 0xFFFD:
return false // invalid UTF-8
case '_', ' ', '/', '.', '-':
return true
default:
return r > 0x7f || // still allows some invalid UTF-8, but that's the spec.
('0' <= r && r <= '9') ||
('a' <= r && r <= 'z') ||
('A' <= r && r <= 'Z')
}
}
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