gotosocial/internal/processing/media/getfile.go

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/*
GoToSocial
Copyright (C) 2021-2023 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 (
"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/iotools"
"github.com/superseriousbusiness/gotosocial/internal/media"
"github.com/superseriousbusiness/gotosocial/internal/transport"
"github.com/superseriousbusiness/gotosocial/internal/uris"
)
func (p *processor) GetFile(ctx context.Context, requestingAccount *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]
owningAccountID := form.AccountID
// get the account that owns the media and make sure it's not suspended
owningAccount, err := p.db.GetAccountByID(ctx, owningAccountID)
if err != nil {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("account with id %s could not be selected from the db: %s", owningAccountID, err))
}
if !owningAccount.SuspendedAt.IsZero() {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("account with id %s is suspended", owningAccountID))
}
// make sure the requesting account and the media account don't block each other
if requestingAccount != nil {
blocked, err := p.db.IsBlocked(ctx, requestingAccount.ID, owningAccountID, true)
if err != nil {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("block status could not be established between accounts %s and %s: %s", owningAccountID, requestingAccount.ID, err))
}
if blocked {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("block exists between accounts %s and %s", owningAccountID, requestingAccount.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, owningAccountID, mediaSize)
case media.TypeAttachment, media.TypeHeader, media.TypeAvatar:
return p.getAttachmentContent(ctx, requestingAccount, wantedMediaID, owningAccountID, 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, owningAccountID 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 != owningAccountID {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("attachment %s is not owned by %s", wantedMediaID, owningAccountID))
}
// 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.retrieveFromStorage(ctx, 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
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.ReadCloser, int64, error) {
t, err := p.transportController.NewTransportForUsername(innerCtx, requestingUsername)
if err != nil {
return nil, 0, err
}
return t.DereferenceMedia(transport.WithFastfail(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 pipe
// remote server ------------> data function ----------------> api caller
// |
// | tee
// |
// ▼
// instance storage
// This pipe will connect the caller to the in-process media retrieval...
pipeReader, pipeWriter := io.Pipe()
// Wrap the output pipe to silence any errors during the actual media
// streaming process. We catch the error later but they must be silenced
// during stream to prevent interruptions to storage of the actual media.
silencedWriter := iotools.SilenceWriter(pipeWriter)
// Pass the reader side of the pipe to the caller to slurp from.
attachmentContent.Content = pipeReader
// Create a data function which injects the writer end of the pipe
// into the data retrieval process. If something goes wrong while
// doing the data retrieval, we hang up the underlying pipeReader
// to indicate to the caller that no data is available. It's up to
// the caller of this processor function to handle that gracefully.
data = func(innerCtx context.Context) (io.ReadCloser, int64, error) {
t, err := p.transportController.NewTransportForUsername(innerCtx, requestingUsername)
if err != nil {
// propagate the transport error to read end of pipe.
_ = pipeWriter.CloseWithError(fmt.Errorf("error getting transport for user: %w", err))
return nil, 0, err
}
readCloser, fileSize, err := t.DereferenceMedia(transport.WithFastfail(innerCtx), remoteMediaIRI)
if err != nil {
// propagate the dereference error to read end of pipe.
_ = pipeWriter.CloseWithError(fmt.Errorf("error dereferencing media: %w", err))
return nil, 0, err
}
// Make a TeeReader so that everything read from the readCloser,
// aka the remote instance, will also be written into the pipe.
teeReader := io.TeeReader(readCloser, silencedWriter)
// Wrap teereader to implement original readcloser's close,
// and also ensuring that we close the pipe from write end.
return iotools.ReadFnCloser(teeReader, func() error {
defer func() {
// We use the error (if any) encountered by the
// silenced writer to close connection to make sure it
// gets propagated to the attachment.Content reader.
_ = pipeWriter.CloseWithError(silencedWriter.Error())
}()
return readCloser.Close()
}), fileSize, nil
}
}
// put the media recached in the queue
processingMedia, err := p.mediaManager.RecacheMedia(ctx, data, nil, 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.retrieveFromStorage(ctx, storagePath, attachmentContent)
}
return attachmentContent, nil
}
func (p *processor) getEmojiContent(ctx context.Context, fileName string, owningAccountID string, emojiSize media.Size) (*apimodel.Content, gtserror.WithCode) {
emojiContent := &apimodel.Content{}
var storagePath string
// reconstruct the static emoji image url -- reason
// for using the static URL rather than full size url
// is that static emojis are always encoded as png,
// so this is more reliable than using full size url
imageStaticURL := uris.GenerateURIForAttachment(owningAccountID, string(media.TypeEmoji), string(media.SizeStatic), fileName, "png")
e, err := p.db.GetEmojiByStaticURL(ctx, imageStaticURL)
if err != nil {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("emoji %s could not be taken from the db: %s", fileName, err))
}
if *e.Disabled {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("emoji %s has been disabled", fileName))
}
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.retrieveFromStorage(ctx, storagePath, emojiContent)
}
func (p *processor) retrieveFromStorage(ctx context.Context, storagePath string, content *apimodel.Content) (*apimodel.Content, gtserror.WithCode) {
if url := p.storage.URL(ctx, storagePath); url != nil {
content.URL = url
return content, nil
}
reader, err := p.storage.GetStream(ctx, storagePath)
if err != nil {
return nil, gtserror.NewErrorNotFound(fmt.Errorf("error retrieving from storage: %s", err))
}
content.Content = reader
return content, nil
}