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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 (
"codeberg.org/gruf/go-debug"
"github.com/gin-gonic/gin"
"github.com/superseriousbusiness/gotosocial/internal/config"
)
// ExtraHeaders returns a new gin middleware which adds various extra headers to the response.
func ExtraHeaders() gin.HandlerFunc {
csp := BuildContentSecurityPolicy()
return func(c *gin.Context) {
// Inform all callers which server implementation this is.
c.Header("Server", "gotosocial")
// Prevent google chrome cohort tracking. Originally this was referred
// to as FlocBlock. Floc was replaced by Topics in 2022 and the spec says
// that interest-cohort will also block Topics (as of 2022-Nov).
//
// See: https://smartframe.io/blog/google-topics-api-everything-you-need-to-know
//
// See: https://github.com/patcg-individual-drafts/topics
c.Header("Permissions-Policy", "browsing-topics=()")
// Inform the browser we only load
// CSS/JS/media using the given policy.
c.Header("Content-Security-Policy", csp)
}
}
func BuildContentSecurityPolicy() string {
// Start with restrictive policy.
policy := "default-src 'self'"
if debug.DEBUG {
// Debug is enabled, allow
// serving things from localhost
// as well (regardless of port).
policy += " localhost:*"
}
s3Endpoint := config.GetStorageS3Endpoint()
if s3Endpoint == "" {
// S3 not configured,
// default policy is OK.
return policy
}
if config.GetStorageS3Proxy() {
// S3 is configured in proxy
// mode, default policy is OK.
return policy
}
// S3 is on and in non-proxy mode, so we need to add the S3 host to
// the policy to allow images and video to be pulled from there too.
// If secure is false,
// use 'http' scheme.
scheme := "https"
if !config.GetStorageS3UseSSL() {
scheme = "http"
}
// Construct endpoint URL.
s3EndpointURLStr := scheme + "://" + s3Endpoint
// When object storage is in use in non-proxied mode, GtS still serves some
// assets itself like the logo, so keep 'self' in there. That should also
// handle any redirects from the fileserver to object storage.
// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/img-src
policy += "; img-src 'self' " + s3EndpointURLStr
// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/media-src
policy += "; media-src 'self' " + s3EndpointURLStr
return policy
}
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