gotosocial/internal/web/etag.go

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/*
GoToSocial
Copyright (C) 2021-2023 GoToSocial Authors admin@gotosocial.org
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package web
import (
// nolint:gosec
"crypto/sha1"
"encoding/hex"
"io"
"time"
"github.com/superseriousbusiness/gotosocial/internal/log"
"codeberg.org/gruf/go-cache/v3"
)
func newETagCache() cache.Cache[string, eTagCacheEntry] {
eTagCache := cache.New[string, eTagCacheEntry](0, 1000, 0)
eTagCache.SetTTL(time.Hour, false)
if !eTagCache.Start(time.Minute) {
log.Panic(nil, "could not start eTagCache")
}
return eTagCache
}
type eTagCacheEntry struct {
eTag string
lastModified time.Time
}
// generateEtag generates a strong (byte-for-byte) etag using
// the entirety of the provided reader.
func generateEtag(r io.Reader) (string, error) {
// nolint:gosec
hash := sha1.New()
if _, err := io.Copy(hash, r); err != nil {
return "", err
}
b := make([]byte, 0, sha1.Size)
b = hash.Sum(b)
return `"` + hex.EncodeToString(b) + `"`, nil
}