mirror of
https://github.com/kubernetes/client-go.git
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761f55c9e0
This is a little more computationally expensive but reduces the likelihood of a potentially malicious cache collision. Signed-off-by: Nic Cope <nicc@rk0n.org> Kubernetes-commit: c5957c284e1d23bdadc98fbbe2bb481fc1f345d4
121 lines
3.9 KiB
Go
121 lines
3.9 KiB
Go
/*
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Copyright 2017 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package disk
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import (
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"bytes"
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"crypto/sha256"
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"fmt"
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"net/http"
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"os"
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"path/filepath"
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"github.com/gregjones/httpcache"
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"github.com/peterbourgon/diskv"
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"k8s.io/klog/v2"
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)
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type cacheRoundTripper struct {
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rt *httpcache.Transport
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}
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// newCacheRoundTripper creates a roundtripper that reads the ETag on
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// response headers and send the If-None-Match header on subsequent
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// corresponding requests.
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func newCacheRoundTripper(cacheDir string, rt http.RoundTripper) http.RoundTripper {
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d := diskv.New(diskv.Options{
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PathPerm: os.FileMode(0750),
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FilePerm: os.FileMode(0660),
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BasePath: cacheDir,
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TempDir: filepath.Join(cacheDir, ".diskv-temp"),
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})
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t := httpcache.NewTransport(&sumDiskCache{disk: d})
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t.Transport = rt
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return &cacheRoundTripper{rt: t}
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}
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func (rt *cacheRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
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return rt.rt.RoundTrip(req)
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}
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func (rt *cacheRoundTripper) CancelRequest(req *http.Request) {
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type canceler interface {
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CancelRequest(*http.Request)
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}
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if cr, ok := rt.rt.Transport.(canceler); ok {
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cr.CancelRequest(req)
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} else {
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klog.Errorf("CancelRequest not implemented by %T", rt.rt.Transport)
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}
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}
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func (rt *cacheRoundTripper) WrappedRoundTripper() http.RoundTripper { return rt.rt.Transport }
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// A sumDiskCache is a cache backend for github.com/gregjones/httpcache. It is
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// similar to httpcache's diskcache package, but uses SHA256 sums to ensure
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// cache integrity at read time rather than fsyncing each cache entry to
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// increase the likelihood they will be persisted at write time. This avoids
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// significant performance degradation on MacOS.
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//
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// See https://github.com/kubernetes/kubernetes/issues/110753 for more.
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type sumDiskCache struct {
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disk *diskv.Diskv
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}
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// Get the requested key from the cache on disk. If Get encounters an error, or
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// the returned value is not a SHA256 sum followed by bytes with a matching
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// checksum it will return false to indicate a cache miss.
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func (c *sumDiskCache) Get(key string) ([]byte, bool) {
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b, err := c.disk.Read(sanitize(key))
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if err != nil || len(b) < sha256.Size {
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return []byte{}, false
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}
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response := b[sha256.Size:]
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want := b[:sha256.Size] // The first 32 bytes of the file should be the SHA256 sum.
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got := sha256.Sum256(response)
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if !bytes.Equal(want, got[:]) {
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return []byte{}, false
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}
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return response, true
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}
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// Set writes the response to a file on disk. The filename will be the SHA256
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// sum of the key. The file will contain a SHA256 sum of the response bytes,
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// followed by said response bytes.
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func (c *sumDiskCache) Set(key string, response []byte) {
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s := sha256.Sum256(response)
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_ = c.disk.Write(sanitize(key), append(s[:], response...)) // Nothing we can do with this error.
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}
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func (c *sumDiskCache) Delete(key string) {
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_ = c.disk.Erase(sanitize(key)) // Nothing we can do with this error.
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}
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// Sanitize an httpcache key such that it can be used as a diskv key, which must
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// be a valid filename. The httpcache key will either be the requested URL (if
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// the request method was GET) or "<method> <url>" for other methods, per the
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// httpcache.cacheKey function.
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func sanitize(key string) string {
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// These keys are not sensitive. We use sha256 to avoid a (potentially
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// malicious) collision causing the wrong cache data to be written or
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// accessed.
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return fmt.Sprintf("%x", sha256.Sum256([]byte(key)))
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}
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