clean up some weirdness in the router (#80)

internal/router/cors.go

@@ -0,0 +1,88 @@
+/*
+   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"
+	"github.com/superseriousbusiness/gotosocial/internal/config"
+)
+
+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(cfg *config.Config, engine *gin.Engine) error {
+	c := cors.New(corsConfig)
+	engine.Use(c)
+	return nil
+}