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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 dereferencing
import (
"context"
"encoding/json"
"net/url"
apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
apiutil "github.com/superseriousbusiness/gotosocial/internal/api/util"
"github.com/superseriousbusiness/gotosocial/internal/gtserror"
"github.com/superseriousbusiness/gotosocial/internal/log"
"github.com/superseriousbusiness/gotosocial/internal/transport"
"github.com/superseriousbusiness/gotosocial/internal/util"
)
// fingerRemoteAccount performs a webfinger call for the
// given username and host, using the provided transport.
//
// The webfinger response will be parsed, and the subject
// domain and AP URI will be extracted and returned.
//
// In case the response cannot be parsed, or the response
// does not contain a valid subject string or AP URI, an
// error will be returned instead.
func (d *Dereferencer) fingerRemoteAccount(
ctx context.Context,
transport transport.Transport,
username string,
host string,
) (
string, // discovered username
string, // discovered account domain
*url.URL, // discovered account URI
error,
) {
// Assemble target namestring for logging.
var target = "@" + username + "@" + host
b, err := transport.Finger(ctx, username, host)
if err != nil {
err = gtserror.Newf("error webfingering %s: %w", target, err)
return "", "", nil, err
}
var resp apimodel.WellKnownResponse
if err := json.Unmarshal(b, &resp); err != nil {
err = gtserror.Newf("error parsing response as JSON for %s: %w", target, err)
return "", "", nil, err
}
if len(resp.Links) == 0 {
err = gtserror.Newf("no links found in response for %s", target)
return "", "", nil, err
}
if resp.Subject == "" {
err = gtserror.Newf("no subject found in response for %s", target)
return "", "", nil, err
}
accUsername, accDomain, err := util.ExtractWebfingerParts(resp.Subject)
if err != nil {
return "", "", nil, gtserror.Newf("error extracting subject parts for %s: %w", target, err)
} else if accUsername != username {
return "", "", nil, gtserror.Newf("response username does not match input for %s: %w", target, err)
}
// Look through links for the first
// one that matches what we need:
//
// - Must be self link.
// - Must be AP type.
// - Valid https/http URI.
for _, link := range resp.Links {
if link.Rel != "self" {
// Not self link, ignore.
continue
}
if !apiutil.ASContentType(link.Type) {
// Not an AP type, ignore.
continue
}
uri, err := url.Parse(link.Href)
if err != nil {
log.Warnf(ctx,
"invalid href for ActivityPub self link %s for %s: %v",
link.Href, target, err,
)
// Funky URL, ignore.
continue
}
if uri.Scheme != "http" && uri.Scheme != "https" {
log.Warnf(ctx,
"invalid href for ActivityPub self link %s for %s: schema must be http or https",
link.Href, target,
)
// Can't handle this
// schema, ignore.
continue
}
// All looks good, return happily!
return accUsername, accDomain, uri, nil
}
return "", "", nil, gtserror.Newf("no suitable self, AP-type link found in webfinger response for %s", target)
}
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