GoToSocial/internal/middleware/cachecontrol.go

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// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// 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 middleware
import (
"strings"
"github.com/gin-gonic/gin"
)
type CacheControlConfig struct {
// Slice of Cache-Control directives, which will be
// joined comma-separated and served as the value of
// the Cache-Control header.
//
// If no directives are set, the Cache-Control header
// will not be sent in the response at all.
//
// For possible Cache-Control directive values, see:
// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control
Directives []string
// Slice of Vary header values, which will be joined
// comma-separated and served as the value of the Vary
// header in the response.
//
// If no Vary header values are supplied, then the
// Vary header will be omitted in the response.
//
// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Vary
Vary []string
}
// CacheControl returns a new gin middleware which allows
// routes to control cache settings on response headers.
func CacheControl(config CacheControlConfig) gin.HandlerFunc {
if len(config.Directives) == 0 {
// No Cache-Control directives provided,
// return empty/stub function.
return func(c *gin.Context) {}
}
// Cache control is usually done on hot paths so
// parse vars outside of the returned function.
var (
ccHeader = strings.Join(config.Directives, ", ")
varyHeader = strings.Join(config.Vary, ", ")
)
if varyHeader == "" {
return func(c *gin.Context) {
c.Header("Cache-Control", ccHeader)
}
}
return func(c *gin.Context) {
c.Header("Cache-Control", ccHeader)
c.Header("Vary", varyHeader)
}
}