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// Copyright 2020 Google LLC All Rights Reserved.
//
// 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 redact contains a simple context signal for redacting requests.
package redact
import (
"context"
"errors"
"net/url"
)
type contextKey string
var redactKey = contextKey("redact")
// NewContext creates a new ctx with the reason for redaction.
func NewContext(ctx context.Context, reason string) context.Context {
return context.WithValue(ctx, redactKey, reason)
}
// FromContext returns the redaction reason, if any.
func FromContext(ctx context.Context) (bool, string) {
reason, ok := ctx.Value(redactKey).(string)
return ok, reason
}
// Error redacts potentially sensitive query parameter values in the URL from the error's message.
//
// If the error is a *url.Error, this returns a *url.Error with the URL redacted.
// Any other error type, or nil, is returned unchanged.
func Error(err error) error {
// If the error is a url.Error, we can redact the URL.
// Otherwise (including if err is nil), we can't redact.
var uerr *url.Error
if ok := errors.As(err, &uerr); !ok {
return err
}
u, perr := url.Parse(uerr.URL)
if perr != nil {
return err // If the URL can't be parsed, just return the original error.
}
uerr.URL = URL(u).String() // Update the URL to the redacted URL.
return uerr
}
// The set of query string keys that we expect to send as part of the registry
// protocol. Anything else is potentially dangerous to leak, as it's probably
// from a redirect. These redirects often included tokens or signed URLs.
var paramAllowlist = map[string]struct{}{
// Token exchange
"scope": {},
"service": {},
// Cross-repo mounting
"mount": {},
"from": {},
// Layer PUT
"digest": {},
// Listing tags and catalog
"n": {},
"last": {},
}
// URL redacts potentially sensitive query parameter values from the URL's query string.
func URL(u *url.URL) *url.URL {
qs := u.Query()
for k, v := range qs {
for i := range v {
if _, ok := paramAllowlist[k]; !ok {
// key is not in the Allowlist
v[i] = "REDACTED"
}
}
}
r := *u
r.RawQuery = qs.Encode()
return &r
}
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