GoToSocial/internal/federation/dereferencing/media.go

272 lines
7.8 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 dereferencing
import (
"context"
"io"
"net/url"
"github.com/superseriousbusiness/gotosocial/internal/config"
"github.com/superseriousbusiness/gotosocial/internal/gtserror"
"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
"github.com/superseriousbusiness/gotosocial/internal/media"
"github.com/superseriousbusiness/gotosocial/internal/util"
)
// GetMedia fetches the media at given remote URL by
// dereferencing it. The passed accountID is used to
// store it as being owned by that account. Additional
// information to set on the media attachment may also
// be provided.
//
// Please note that even if an error is returned,
// a media model may still be returned if the error
// was only encountered during actual dereferencing.
// In this case, it will act as a placeholder.
//
// Also note that since account / status dereferencing is
// already protected by per-uri locks, and that fediverse
// media is generally not shared between accounts (etc),
// there aren't any concurrency protections against multiple
// insertion / dereferencing of media at remoteURL. Worst
// case scenario, an extra media entry will be inserted
// and the scheduled cleaner.Cleaner{} will catch it!
func (d *Dereferencer) GetMedia(
ctx context.Context,
requestUser string,
accountID string, // media account owner
remoteURL string,
info media.AdditionalMediaInfo,
) (
*gtsmodel.MediaAttachment,
error,
) {
// Ensure we have a valid remote URL.
url, err := url.Parse(remoteURL)
if err != nil {
err := gtserror.Newf("invalid media remote url %s: %w", remoteURL, err)
return nil, err
}
return d.processMediaSafeley(ctx,
remoteURL,
func() (*media.ProcessingMedia, error) {
// Fetch transport for the provided request user from controller.
tsport, err := d.transportController.NewTransportForUsername(ctx,
requestUser,
)
if err != nil {
return nil, gtserror.Newf("failed getting transport for %s: %w", requestUser, err)
}
// Get maximum supported remote media size.
maxsz := int64(config.GetMediaRemoteMaxSize()) // #nosec G115 -- Already validated.
// Create media with prepared info.
return d.mediaManager.CreateMedia(
ctx,
accountID,
func(ctx context.Context) (io.ReadCloser, error) {
return tsport.DereferenceMedia(ctx, url, maxsz)
},
info,
)
},
)
}
// RefreshMedia ensures that given media is up-to-date,
// both in terms of being cached in local instance,
// storage and compared to extra info in information
// in given gtsmodel.AdditionMediaInfo{}. This handles
// the case of local emoji by returning early.
//
// Please note that even if an error is returned,
// a media model may still be returned if the error
// was only encountered during actual dereferencing.
// In this case, it will act as a placeholder.
//
// Also note that since account / status dereferencing is
// already protected by per-uri locks, and that fediverse
// media is generally not shared between accounts (etc),
// there aren't any concurrency protections against multiple
// insertion / dereferencing of media at remoteURL. Worst
// case scenario, an extra media entry will be inserted
// and the scheduled cleaner.Cleaner{} will catch it!
func (d *Dereferencer) RefreshMedia(
ctx context.Context,
requestUser string,
attach *gtsmodel.MediaAttachment,
info media.AdditionalMediaInfo,
force bool,
) (
*gtsmodel.MediaAttachment,
error,
) {
// Can't refresh local.
if attach.IsLocal() {
return attach, nil
}
// Check emoji is up-to-date
// with provided extra info.
switch {
case info.Blurhash != nil &&
*info.Blurhash != attach.Blurhash:
attach.Blurhash = *info.Blurhash
force = true
case info.Description != nil &&
*info.Description != attach.Description:
attach.Description = *info.Description
force = true
case info.RemoteURL != nil &&
*info.RemoteURL != attach.RemoteURL:
attach.RemoteURL = *info.RemoteURL
force = true
}
// Check if needs updating.
if *attach.Cached && !force {
return attach, nil
}
// Ensure we have a valid remote URL.
url, err := url.Parse(attach.RemoteURL)
if err != nil {
err := gtserror.Newf("invalid media remote url %s: %w", attach.RemoteURL, err)
return nil, err
}
// Pass along for safe processing.
return d.processMediaSafeley(ctx,
attach.RemoteURL,
func() (*media.ProcessingMedia, error) {
// Fetch transport for the provided request user from controller.
tsport, err := d.transportController.NewTransportForUsername(ctx,
requestUser,
)
if err != nil {
return nil, gtserror.Newf("failed getting transport for %s: %w", requestUser, err)
}
// Get maximum supported remote media size.
maxsz := int64(config.GetMediaRemoteMaxSize()) // #nosec G115 -- Already validated.
// Recache media with prepared info,
// this will also update media in db.
return d.mediaManager.CacheMedia(
attach,
func(ctx context.Context) (io.ReadCloser, error) {
return tsport.DereferenceMedia(ctx, url, maxsz)
},
), nil
},
)
}
// updateAttachment handles the case of an existing media attachment
// that *may* have changes or need recaching. it checks for changed
// fields, updating in the database if so, and recaches uncached media.
func (d *Dereferencer) updateAttachment(
ctx context.Context,
requestUser string,
existing *gtsmodel.MediaAttachment, // existing attachment
attach *gtsmodel.MediaAttachment, // (optional) changed media
) (
*gtsmodel.MediaAttachment, // always set
error,
) {
var info media.AdditionalMediaInfo
if attach != nil {
// Set optional extra information,
// (will later check for changes).
info.Description = &attach.Description
info.Blurhash = &attach.Blurhash
info.RemoteURL = &attach.RemoteURL
}
// Ensure media is cached.
return d.RefreshMedia(ctx,
requestUser,
existing,
info,
false,
)
}
// processingEmojiSafely provides concurrency-safe processing of
// an emoji with given shortcode+domain. if a copy of the emoji is
// not already being processed, the given 'process' callback will
// be used to generate new *media.ProcessingEmoji{} instance.
func (d *Dereferencer) processMediaSafeley(
ctx context.Context,
remoteURL string,
process func() (*media.ProcessingMedia, error),
) (
media *gtsmodel.MediaAttachment,
err error,
) {
// Acquire map lock.
d.derefMediaMu.Lock()
// Ensure unlock only done once.
unlock := d.derefMediaMu.Unlock
unlock = util.DoOnce(unlock)
defer unlock()
// Look for an existing deref in progress.
processing, ok := d.derefMedia[remoteURL]
if !ok {
// Start new processing emoji.
processing, err = process()
if err != nil {
return nil, err
}
// Add processing media to hash map.
d.derefMedia[remoteURL] = processing
defer func() {
// Remove on finish.
d.derefMediaMu.Lock()
delete(d.derefMedia, remoteURL)
d.derefMediaMu.Unlock()
}()
}
// Unlock map.
unlock()
// Perform media load operation.
media, err = processing.Load(ctx)
if err != nil {
err = gtserror.Newf("error loading media %s: %w", remoteURL, err)
// TODO: in time we should return checkable flags by gtserror.Is___()
// which can determine if loading error should allow remaining placeholder.
}
return
}