gotosocial/internal/processing/media/getfile.go

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/*
GoToSocial
2021-12-20 17:42:19 +00:00
Copyright (C) 2021-2022 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 media
import (
"bufio"
"context"
"fmt"
"io"
"net/url"
"strings"
apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
"github.com/superseriousbusiness/gotosocial/internal/gtserror"
"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
"github.com/superseriousbusiness/gotosocial/internal/media"
)
func (p *processor) GetFile(ctx context.Context, account *gtsmodel.Account, form *apimodel.GetContentRequestForm) (*apimodel.Content, gtserror.WithCode) {
// parse the form fields
mediaSize, err := media.ParseMediaSize(form.MediaSize)
if err != nil {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("media size %s not valid", form.MediaSize))
}
mediaType, err := media.ParseMediaType(form.MediaType)
if err != nil {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("media type %s not valid", form.MediaType))
}
spl := strings.Split(form.FileName, ".")
if len(spl) != 2 || spl[0] == "" || spl[1] == "" {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("file name %s not parseable", form.FileName))
}
wantedMediaID := spl[0]
expectedAccountID := form.AccountID
// get the account that owns the media and make sure it's not suspended
acct, err := p.db.GetAccountByID(ctx, expectedAccountID)
if err != nil {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("account with id %s could not be selected from the db: %s", expectedAccountID, err))
}
if !acct.SuspendedAt.IsZero() {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("account with id %s is suspended", expectedAccountID))
}
// make sure the requesting account and the media account don't block each other
if account != nil {
blocked, err := p.db.IsBlocked(ctx, account.ID, expectedAccountID, true)
if err != nil {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("block status could not be established between accounts %s and %s: %s", expectedAccountID, account.ID, err))
}
if blocked {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("block exists between accounts %s and %s", expectedAccountID, account.ID))
}
}
// the way we store emojis is a little different from the way we store other attachments,
// so we need to take different steps depending on the media type being requested
switch mediaType {
case media.TypeEmoji:
return p.getEmojiContent(ctx, wantedMediaID, mediaSize)
case media.TypeAttachment, media.TypeHeader, media.TypeAvatar:
return p.getAttachmentContent(ctx, account, wantedMediaID, expectedAccountID, mediaSize)
default:
return nil, gtserror.NewErrorNotFound(fmt.Errorf("media type %s not recognized", mediaType))
}
}
func (p *processor) getAttachmentContent(ctx context.Context, requestingAccount *gtsmodel.Account, wantedMediaID string, expectedAccountID string, mediaSize media.Size) (*apimodel.Content, gtserror.WithCode) {
attachmentContent := &apimodel.Content{}
var storagePath string
// retrieve attachment from the database and do basic checks on it
a, err := p.db.GetAttachmentByID(ctx, wantedMediaID)
if err != nil {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("attachment %s could not be taken from the db: %s", wantedMediaID, err))
}
if a.AccountID != expectedAccountID {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("attachment %s is not owned by %s", wantedMediaID, expectedAccountID))
}
// get file information from the attachment depending on the requested media size
switch mediaSize {
case media.SizeOriginal:
attachmentContent.ContentType = a.File.ContentType
attachmentContent.ContentLength = int64(a.File.FileSize)
storagePath = a.File.Path
case media.SizeSmall:
attachmentContent.ContentType = a.Thumbnail.ContentType
attachmentContent.ContentLength = int64(a.Thumbnail.FileSize)
storagePath = a.Thumbnail.Path
default:
return nil, gtserror.NewErrorNotFound(fmt.Errorf("media size %s not recognized for attachment", mediaSize))
}
// if we have the media cached on our server already, we can now simply return it from storage
if a.Cached {
return p.streamFromStorage(storagePath, attachmentContent)
}
// if we don't have it cached, then we can assume two things:
// 1. this is remote media, since local media should never be uncached
// 2. we need to fetch it again using a transport and the media manager
remoteMediaIRI, err := url.Parse(a.RemoteURL)
if err != nil {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("error parsing remote media iri %s: %s", a.RemoteURL, err))
}
// use an empty string as requestingUsername to use the instance account, unless the request for this
// media has been http signed, then use the requesting account to make the request to remote server
var requestingUsername string
if requestingAccount != nil {
requestingUsername = requestingAccount.Username
}
var data media.DataFunc
var postDataCallback media.PostDataCallbackFunc
if mediaSize == media.SizeSmall {
// if it's the thumbnail that's requested then the user will have to wait a bit while we process the
// large version and derive a thumbnail from it, so use the normal recaching procedure: fetch the media,
// process it, then return the thumbnail data
data = func(innerCtx context.Context) (io.Reader, int, error) {
transport, err := p.transportController.NewTransportForUsername(innerCtx, requestingUsername)
if err != nil {
return nil, 0, err
}
return transport.DereferenceMedia(innerCtx, remoteMediaIRI)
}
} else {
// if it's the full-sized version being requested, we can cheat a bit by streaming data to the user as
// it's retrieved from the remote server, using tee; this saves the user from having to wait while
// we process the media on our side
//
// this looks a bit like this:
//
// http fetch buffered pipe
// remote server ------------> data function ----------------> api caller
// |
// | tee
// |
// ▼
// instance storage
// Buffer each end of the pipe, so that if the caller drops the connection during the flow, the tee
// reader can continue without having to worry about tee-ing into a closed or blocked pipe.
pipeReader, pipeWriter := io.Pipe()
bufferedWriter := bufio.NewWriterSize(pipeWriter, int(attachmentContent.ContentLength))
bufferedReader := bufio.NewReaderSize(pipeReader, int(attachmentContent.ContentLength))
// the caller will read from the buffered reader, so it doesn't matter if they drop out without reading everything
attachmentContent.Content = bufferedReader
data = func(innerCtx context.Context) (io.Reader, int, error) {
transport, err := p.transportController.NewTransportForUsername(innerCtx, requestingUsername)
if err != nil {
return nil, 0, err
}
readCloser, fileSize, err := transport.DereferenceMedia(innerCtx, remoteMediaIRI)
if err != nil {
return nil, 0, err
}
// everything read from the readCloser by the media manager will be written into the bufferedWriter
teeReader := io.TeeReader(readCloser, bufferedWriter)
return teeReader, fileSize, nil
}
// close the pipewriter after data has been piped into it, so the reader on the other side doesn't block;
// we don't need to close the reader here because that's the caller's responsibility
postDataCallback = func(innerCtx context.Context) error {
// flush the buffered writer into the buffer of the reader...
if err := bufferedWriter.Flush(); err != nil {
return err
}
// and close the underlying pipe writer
if err := pipeWriter.Close(); err != nil {
return err
}
return nil
}
}
// put the media recached in the queue
processingMedia, err := p.mediaManager.RecacheMedia(ctx, data, postDataCallback, wantedMediaID)
if err != nil {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("error recaching media: %s", err))
}
// if it's the thumbnail, stream the processed thumbnail from storage, after waiting for processing to finish
if mediaSize == media.SizeSmall {
// below function call blocks until all processing on the attachment has finished...
if _, err := processingMedia.LoadAttachment(ctx); err != nil {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("error loading recached attachment: %s", err))
}
// ... so now we can safely return it
return p.streamFromStorage(storagePath, attachmentContent)
}
return attachmentContent, nil
}
func (p *processor) getEmojiContent(ctx context.Context, wantedEmojiID string, emojiSize media.Size) (*apimodel.Content, gtserror.WithCode) {
emojiContent := &apimodel.Content{}
var storagePath string
e := &gtsmodel.Emoji{}
if err := p.db.GetByID(ctx, wantedEmojiID, e); err != nil {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("emoji %s could not be taken from the db: %s", wantedEmojiID, err))
}
if e.Disabled {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("emoji %s has been disabled", wantedEmojiID))
}
switch emojiSize {
case media.SizeOriginal:
emojiContent.ContentType = e.ImageContentType
emojiContent.ContentLength = int64(e.ImageFileSize)
storagePath = e.ImagePath
case media.SizeStatic:
emojiContent.ContentType = e.ImageStaticContentType
emojiContent.ContentLength = int64(e.ImageStaticFileSize)
storagePath = e.ImageStaticPath
default:
return nil, gtserror.NewErrorNotFound(fmt.Errorf("media size %s not recognized for emoji", emojiSize))
}
return p.streamFromStorage(storagePath, emojiContent)
}
func (p *processor) streamFromStorage(storagePath string, content *apimodel.Content) (*apimodel.Content, gtserror.WithCode) {
reader, err := p.storage.GetStream(storagePath)
if err != nil {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("error retrieving from storage: %s", err))
}
content.Content = reader
return content, nil
}