etag.go (1661B)
1 // GoToSocial 2 // Copyright (C) GoToSocial Authors admin@gotosocial.org 3 // SPDX-License-Identifier: AGPL-3.0-or-later 4 // 5 // This program is free software: you can redistribute it and/or modify 6 // it under the terms of the GNU Affero General Public License as published by 7 // the Free Software Foundation, either version 3 of the License, or 8 // (at your option) any later version. 9 // 10 // This program is distributed in the hope that it will be useful, 11 // but WITHOUT ANY WARRANTY; without even the implied warranty of 12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 // GNU Affero General Public License for more details. 14 // 15 // You should have received a copy of the GNU Affero General Public License 16 // along with this program. If not, see <http://www.gnu.org/licenses/>. 17 18 package web 19 20 import ( 21 // nolint:gosec 22 "crypto/sha1" 23 "encoding/hex" 24 "io" 25 "time" 26 27 "github.com/superseriousbusiness/gotosocial/internal/log" 28 29 "codeberg.org/gruf/go-cache/v3" 30 ) 31 32 func newETagCache() cache.Cache[string, eTagCacheEntry] { 33 eTagCache := cache.New[string, eTagCacheEntry](0, 1000, 0) 34 eTagCache.SetTTL(time.Hour, false) 35 if !eTagCache.Start(time.Minute) { 36 log.Panic(nil, "could not start eTagCache") 37 } 38 return eTagCache 39 } 40 41 type eTagCacheEntry struct { 42 eTag string 43 lastModified time.Time 44 } 45 46 // generateEtag generates a strong (byte-for-byte) etag using 47 // the entirety of the provided reader. 48 func generateEtag(r io.Reader) (string, error) { 49 // nolint:gosec 50 hash := sha1.New() 51 52 if _, err := io.Copy(hash, r); err != nil { 53 return "", err 54 } 55 56 b := make([]byte, 0, sha1.Size) 57 b = hash.Sum(b) 58 59 return `"` + hex.EncodeToString(b) + `"`, nil 60 }