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admin: support ETag on config endpoints (#4579)
* admin: support ETags * support etags Co-authored-by: Matt Holt <mholt@users.noreply.github.com>
This commit is contained in:
parent
8bac134f26
commit
f259ed52bb
3 changed files with 104 additions and 6 deletions
21
admin.go
21
admin.go
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@ -21,10 +21,13 @@ import (
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"crypto/tls"
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"crypto/x509"
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"encoding/base64"
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"encoding/hex"
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"encoding/json"
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"errors"
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"expvar"
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"fmt"
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"hash"
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"hash/fnv"
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"io"
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"net"
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"net/http"
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@ -894,16 +897,30 @@ func (h adminHandler) originAllowed(origin *url.URL) bool {
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return false
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}
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// etagHasher returns a the hasher we used on the config to both
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// produce and verify ETags.
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func etagHasher() hash.Hash32 { return fnv.New32a() }
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func handleConfig(w http.ResponseWriter, r *http.Request) error {
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switch r.Method {
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case http.MethodGet:
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w.Header().Set("Content-Type", "application/json")
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// Set the ETag as a trailer header.
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// The alternative is to write the config to a buffer, and
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// then hash that.
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w.Header().Set("Trailer", "ETag")
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err := readConfig(r.URL.Path, w)
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hash := etagHasher()
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configWriter := io.MultiWriter(w, hash)
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err := readConfig(r.URL.Path, configWriter)
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if err != nil {
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return APIError{HTTPStatus: http.StatusBadRequest, Err: err}
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}
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// we could consider setting up a sync.Pool for the summed
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// hashes to reduce GC pressure.
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w.Header().Set("ETag", r.URL.Path+" "+hex.EncodeToString(hash.Sum(nil)))
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return nil
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case http.MethodPost,
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@ -937,7 +954,7 @@ func handleConfig(w http.ResponseWriter, r *http.Request) error {
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forceReload := r.Header.Get("Cache-Control") == "must-revalidate"
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err := changeConfig(r.Method, r.URL.Path, body, forceReload)
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err := changeConfig(r.Method, r.URL.Path, body, r.Header.Get("If-Match"), forceReload)
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if err != nil && !errors.Is(err, errSameConfig) {
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return err
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}
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@ -15,7 +15,9 @@
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package caddy
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import (
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"encoding/hex"
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"encoding/json"
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"net/http"
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"reflect"
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"sync"
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"testing"
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@ -139,10 +141,57 @@ func TestLoadConcurrent(t *testing.T) {
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wg.Done()
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}()
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}
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wg.Wait()
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}
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type fooModule struct {
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IntField int
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StrField string
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}
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func (fooModule) CaddyModule() ModuleInfo {
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return ModuleInfo{
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ID: "foo",
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New: func() Module { return new(fooModule) },
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}
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}
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func (fooModule) Start() error { return nil }
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func (fooModule) Stop() error { return nil }
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func TestETags(t *testing.T) {
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RegisterModule(fooModule{})
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if err := Load([]byte(`{"apps": {"foo": {"strField": "abc", "intField": 0}}}`), true); err != nil {
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t.Fatalf("loading: %s", err)
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}
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const key = "/" + rawConfigKey + "/apps/foo"
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// try update the config with the wrong etag
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err := changeConfig(http.MethodPost, key, []byte(`{"strField": "abc", "intField": 1}}`), "/"+rawConfigKey+" not_an_etag", false)
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if apiErr, ok := err.(APIError); !ok || apiErr.HTTPStatus != http.StatusPreconditionFailed {
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t.Fatalf("expected precondition failed; got %v", err)
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}
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// get the etag
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hash := etagHasher()
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if err := readConfig(key, hash); err != nil {
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t.Fatalf("reading: %s", err)
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}
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// do the same update with the correct key
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err = changeConfig(http.MethodPost, key, []byte(`{"strField": "abc", "intField": 1}`), key+" "+hex.EncodeToString(hash.Sum(nil)), false)
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if err != nil {
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t.Fatalf("expected update to work; got %v", err)
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}
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// now try another update. The hash should no longer match and we should get precondition failed
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err = changeConfig(http.MethodPost, key, []byte(`{"strField": "abc", "intField": 2}`), key+" "+hex.EncodeToString(hash.Sum(nil)), false)
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if apiErr, ok := err.(APIError); !ok || apiErr.HTTPStatus != http.StatusPreconditionFailed {
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t.Fatalf("expected precondition failed; got %v", err)
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}
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}
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func BenchmarkLoad(b *testing.B) {
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for i := 0; i < b.N; i++ {
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Load(testCfg, true)
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38
caddy.go
38
caddy.go
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@ -17,6 +17,7 @@ package caddy
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import (
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"bytes"
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"context"
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"encoding/hex"
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"encoding/json"
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"errors"
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"fmt"
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@ -111,7 +112,7 @@ func Load(cfgJSON []byte, forceReload bool) error {
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}
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}()
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err := changeConfig(http.MethodPost, "/"+rawConfigKey, cfgJSON, forceReload)
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err := changeConfig(http.MethodPost, "/"+rawConfigKey, cfgJSON, "", forceReload)
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if errors.Is(err, errSameConfig) {
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err = nil // not really an error
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}
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@ -125,7 +126,12 @@ func Load(cfgJSON []byte, forceReload bool) error {
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// occur unless forceReload is true. If the config is unchanged and not
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// forcefully reloaded, then errConfigUnchanged This function is safe for
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// concurrent use.
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func changeConfig(method, path string, input []byte, forceReload bool) error {
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// The ifMatchHeader can optionally be given a string of the format:
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// "<path> <hash>"
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// where <path> is the absolute path in the config and <hash> is the expected hash of
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// the config at that path. If the hash in the ifMatchHeader doesn't match
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// the hash of the config, then an APIError with status 412 will be returned.
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func changeConfig(method, path string, input []byte, ifMatchHeader string, forceReload bool) error {
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switch method {
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case http.MethodGet,
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http.MethodHead,
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@ -138,6 +144,32 @@ func changeConfig(method, path string, input []byte, forceReload bool) error {
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currentCfgMu.Lock()
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defer currentCfgMu.Unlock()
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if ifMatchHeader != "" {
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// read out the parts
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parts := strings.Fields(ifMatchHeader)
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if len(parts) != 2 {
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return APIError{
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HTTPStatus: http.StatusBadRequest,
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Err: fmt.Errorf("malformed If-Match header; expect format \"<path> <hash>\""),
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}
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}
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// get the current hash of the config
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// at the given path
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hash := etagHasher()
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err := unsyncedConfigAccess(http.MethodGet, parts[0], nil, hash)
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if err != nil {
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return err
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}
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if hex.EncodeToString(hash.Sum(nil)) != parts[1] {
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return APIError{
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HTTPStatus: http.StatusPreconditionFailed,
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Err: fmt.Errorf("If-Match header did not match current config hash"),
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}
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}
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}
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err := unsyncedConfigAccess(method, path, input, nil)
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if err != nil {
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return err
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@ -500,7 +532,7 @@ func finishSettingUp(ctx Context, cfg *Config) error {
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runLoadedConfig := func(config []byte) error {
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logger.Info("applying dynamically-loaded config")
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err := changeConfig(http.MethodPost, "/"+rawConfigKey, config, false)
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err := changeConfig(http.MethodPost, "/"+rawConfigKey, config, "", false)
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if errors.Is(err, errSameConfig) {
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return err
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}
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