wings/router/downloader/downloader.go

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package downloader
import (
"context"
"emperror.dev/errors"
"encoding/json"
"github.com/google/uuid"
"github.com/pterodactyl/wings/server"
"io"
"net/http"
"net/url"
"path/filepath"
"strings"
"sync"
"time"
)
type Counter struct {
total int
onWrite func(total int)
}
func (c *Counter) Write(p []byte) (int, error) {
n := len(p)
c.total += n
c.onWrite(c.total)
return n, nil
}
type Downloader struct {
mu sync.RWMutex
downloadCache map[string]*Download
serverCache map[string][]string
}
type DownloadRequest struct {
URL *url.URL
Directory string
}
type Download struct {
Identifier string
mu sync.RWMutex
req DownloadRequest
server *server.Server
progress float64
cancelFunc *context.CancelFunc
}
var client = &http.Client{Timeout: time.Hour * 12}
var instance = &Downloader{
// Tracks all of the active downloads.
downloadCache: make(map[string]*Download),
// Tracks all of the downloads active for a given server instance. This is
// primarily used to make things quicker and keep the code a little more
// legible throughout here.
serverCache: make(map[string][]string),
}
// Starts a new tracked download which allows for cancelation later on by calling
// the Downloader.Cancel function.
func New(s *server.Server, r DownloadRequest) *Download {
dl := Download{
Identifier: uuid.Must(uuid.NewRandom()).String(),
req: r,
server: s,
}
instance.track(&dl)
return &dl
}
// Returns all of the tracked downloads for a given server instance.
func ByServer(sid string) []*Download {
instance.mu.Lock()
defer instance.mu.Unlock()
var downloads []*Download
if v, ok := instance.serverCache[sid]; ok {
for _, id := range v {
if dl, dlok := instance.downloadCache[id]; dlok {
downloads = append(downloads, dl)
}
}
}
return downloads
}
// Returns a single Download matching a given identifier. If no download is found
// the second argument in the response will be false.
func ByID(dlid string) *Download {
return instance.find(dlid)
}
//goland:noinspection GoVetCopyLock
func (dl Download) MarshalJSON() ([]byte, error) {
return json.Marshal(struct {
Identifier string
Progress float64
}{
Identifier: dl.Identifier,
Progress: dl.Progress(),
})
}
// Executes a given download for the server and begins writing the file to the disk. Once
// completed the download will be removed from the cache.
func (dl *Download) Execute() error {
ctx, cancel := context.WithTimeout(context.Background(), time.Hour*12)
dl.cancelFunc = &cancel
defer dl.Cancel()
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req, err := http.NewRequestWithContext(ctx, http.MethodGet, dl.req.URL.String(), nil)
if err != nil {
return errors.WrapIf(err, "downloader: failed to create request")
}
req.Header.Set("User-Agent", "Pterodactyl Panel (https://pterodactyl.io)")
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res, err := client.Do(req) // lgtm [go/request-forgery]
if err != nil {
return errors.New("downloader: failed opening request to download file")
}
defer res.Body.Close()
if res.StatusCode != http.StatusOK {
return errors.New("downloader: got bad response status from endpoint: " + res.Status)
}
// If there is a Content-Length header on this request go ahead and check that we can
// even write the whole file before beginning this process. If there is no header present
// we'll just have to give it a spin and see how it goes.
if res.ContentLength > 0 {
if err := dl.server.Filesystem().HasSpaceFor(res.ContentLength); err != nil {
return errors.WrapIf(err, "downloader: failed to write file: not enough space")
}
}
fnameparts := strings.Split(dl.req.URL.Path, "/")
p := filepath.Join(dl.req.Directory, fnameparts[len(fnameparts)-1])
dl.server.Log().WithField("path", p).Debug("writing remote file to disk")
r := io.TeeReader(res.Body, dl.counter(res.ContentLength))
if err := dl.server.Filesystem().Writefile(p, r); err != nil {
return errors.WrapIf(err, "downloader: failed to write file to server directory")
}
return nil
}
// Cancels a running download and frees up the associated resources. If a file is being
// written a partial file will remain present on the disk.
func (dl *Download) Cancel() {
if dl.cancelFunc != nil {
(*dl.cancelFunc)()
}
instance.remove(dl.Identifier)
}
// Checks if the given download belongs to the provided server.
func (dl *Download) BelongsTo(s *server.Server) bool {
return dl.server.Id() == s.Id()
}
// Returns the current progress of the download as a float value between 0 and 1 where
// 1 indicates that the download is completed.
func (dl *Download) Progress() float64 {
dl.mu.RLock()
defer dl.mu.RUnlock()
return dl.progress
}
// Handles a write event by updating the progress completed percentage and firing off
// events to the server websocket as needed.
func (dl *Download) counter(contentLength int64) *Counter {
onWrite := func(t int) {
dl.mu.Lock()
defer dl.mu.Unlock()
dl.progress = float64(t) / float64(contentLength)
}
return &Counter{
onWrite: onWrite,
}
}
// Tracks a download in the internal cache for this instance.
func (d *Downloader) track(dl *Download) {
d.mu.Lock()
defer d.mu.Unlock()
sid := dl.server.Id()
if _, ok := d.downloadCache[dl.Identifier]; !ok {
d.downloadCache[dl.Identifier] = dl
if _, ok := d.serverCache[sid]; !ok {
d.serverCache[sid] = []string{}
}
d.serverCache[sid] = append(d.serverCache[sid], dl.Identifier)
}
}
// Finds a given download entry using the provided ID and returns it.
func (d *Downloader) find(dlid string) *Download {
d.mu.RLock()
defer d.mu.RUnlock()
if entry, ok := d.downloadCache[dlid]; ok {
return entry
}
return nil
}
// Remove the given download reference from the cache storing them. This also updates
// the slice of active downloads for a given server to not include this download.
func (d *Downloader) remove(dlid string) {
d.mu.Lock()
defer d.mu.Unlock()
if _, ok := d.downloadCache[dlid]; !ok {
return
}
sid := d.downloadCache[dlid].server.Id()
delete(d.downloadCache, dlid)
if tracked, ok := d.serverCache[sid]; ok {
var out []string
for _, k := range tracked {
if k != dlid {
out = append(out, k)
}
}
d.serverCache[sid] = out
}
}