109 lines
3.7 KiB
Go
109 lines
3.7 KiB
Go
// 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 util
|
|
|
|
import (
|
|
"errors"
|
|
"fmt"
|
|
|
|
"github.com/gin-gonic/gin"
|
|
)
|
|
|
|
// ActivityPubAcceptHeaders represents the Accept headers mentioned here:
|
|
var ActivityPubAcceptHeaders = []MIME{
|
|
AppActivityJSON,
|
|
AppActivityLDJSON,
|
|
}
|
|
|
|
// JSONAcceptHeaders is a slice of offers that just contains application/json types.
|
|
var JSONAcceptHeaders = []MIME{
|
|
AppJSON,
|
|
}
|
|
|
|
// HTMLOrJSONAcceptHeaders is a slice of offers that prefers TextHTML and will
|
|
// fall back to JSON if necessary. This is useful for error handling, since it can
|
|
// be used to serve a nice HTML page if the caller accepts that, or just JSON if not.
|
|
var HTMLOrJSONAcceptHeaders = []MIME{
|
|
TextHTML,
|
|
AppJSON,
|
|
}
|
|
|
|
// HTMLAcceptHeaders is a slice of offers that just contains text/html types.
|
|
var HTMLAcceptHeaders = []MIME{
|
|
TextHTML,
|
|
}
|
|
|
|
// HTMLOrActivityPubHeaders matches text/html first, then activitypub types.
|
|
// This is useful for user URLs that a user might go to in their browser.
|
|
// https://www.w3.org/TR/activitypub/#retrieving-objects
|
|
var HTMLOrActivityPubHeaders = []MIME{
|
|
TextHTML,
|
|
AppActivityJSON,
|
|
AppActivityLDJSON,
|
|
}
|
|
|
|
var HostMetaHeaders = []MIME{
|
|
AppXMLXRD,
|
|
AppXML,
|
|
}
|
|
|
|
// NegotiateAccept takes the *gin.Context from an incoming request, and a
|
|
// slice of Offers, and performs content negotiation for the given request
|
|
// with the given content-type offers. It will return a string representation
|
|
// of the first suitable content-type, or an error if something goes wrong or
|
|
// a suitable content-type cannot be matched.
|
|
//
|
|
// For example, if the request in the *gin.Context has Accept headers of value
|
|
// [application/json, text/html], and the provided offers are of value
|
|
// [application/json, application/xml], then the returned string will be
|
|
// 'application/json', which indicates the content-type that should be returned.
|
|
//
|
|
// If the length of offers is 0, then an error will be returned, so this function
|
|
// should only be called in places where format negotiation is actually needed.
|
|
//
|
|
// If there are no Accept headers in the request, then the first offer will be returned,
|
|
// under the assumption that it's better to serve *something* than error out completely.
|
|
//
|
|
// Callers can use the offer slices exported in this package as shortcuts for
|
|
// often-used Accept types.
|
|
//
|
|
// See https://developer.mozilla.org/en-US/docs/Web/HTTP/Content_negotiation#server-driven_content_negotiation
|
|
func NegotiateAccept(c *gin.Context, offers ...MIME) (string, error) {
|
|
if len(offers) == 0 {
|
|
return "", errors.New("no format offered")
|
|
}
|
|
|
|
strings := []string{}
|
|
for _, o := range offers {
|
|
strings = append(strings, string(o))
|
|
}
|
|
|
|
accepts := c.Request.Header.Values("Accept")
|
|
if len(accepts) == 0 {
|
|
// there's no accept header set, just return the first offer
|
|
return strings[0], nil
|
|
}
|
|
|
|
format := c.NegotiateFormat(strings...)
|
|
if format == "" {
|
|
return "", fmt.Errorf("no format can be offered for requested Accept header(s) %s; this endpoint offers %s", accepts, offers)
|
|
}
|
|
|
|
return format, nil
|
|
}
|