gotosocial/internal/router/cors.go

/*
   GoToSocial
   Copyright (C) 2021 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 router

import (
	"time"

	"github.com/gin-contrib/cors"
	"github.com/gin-gonic/gin"
)

var corsConfig = cors.Config{
	// TODO: make this customizable so instance admins can specify an origin for CORS requests
	AllowAllOrigins: true,

	// adds the following:
	// 	"chrome-extension://"
	// 	"safari-extension://"
	// 	"moz-extension://"
	// 	"ms-browser-extension://"
	AllowBrowserExtensions: true,
	AllowMethods: []string{
		"POST",
		"PUT",
		"DELETE",
		"GET",
		"PATCH",
		"OPTIONS",
	},
	AllowHeaders: []string{
		// basic cors stuff
		"Origin",
		"Content-Length",
		"Content-Type",

		// needed to pass oauth bearer tokens
		"Authorization",

		// needed for websocket upgrade requests
		"Upgrade",
		"Sec-WebSocket-Extensions",
		"Sec-WebSocket-Key",
		"Sec-WebSocket-Protocol",
		"Sec-WebSocket-Version",
		"Connection",
	},
	AllowWebSockets: true,
	ExposeHeaders: []string{
		// needed for accessing next/prev links when making GET timeline requests
		"Link",

		// needed so clients can handle rate limits
		"X-RateLimit-Reset",
		"X-RateLimit-Limit",
		"X-RateLimit-Remaining",
		"X-Request-Id",

		// websocket stuff
		"Connection",
		"Sec-WebSocket-Accept",
		"Upgrade",
	},
	MaxAge: 2 * time.Minute,
}

// useCors attaches the corsConfig above to the given gin engine
func useCors(engine *gin.Engine) error {
	c := cors.New(corsConfig)
	engine.Use(c)
	return nil
}