soundcloak/lib/restream/init.go

package restream

import (
	"bytes"
	"image/jpeg"
	"io"
	"sync"

	"github.com/bogem/id3v2/v2"
	"github.com/gcottom/mp4meta"
	"github.com/gcottom/oggmeta"
	"github.com/gofiber/fiber/v2"
	"github.com/maid-zone/soundcloak/lib/cfg"
	"github.com/maid-zone/soundcloak/lib/preferences"
	"github.com/maid-zone/soundcloak/lib/sc"
	"github.com/valyala/fasthttp"
)

var httpc *fasthttp.HostClient
var httpc_aac *fasthttp.HostClient
var httpc_image *fasthttp.HostClient

type reader struct {
	parts    [][]byte
	leftover []byte
	index    int

	req    *fasthttp.Request
	resp   *fasthttp.Response
	client *fasthttp.HostClient
}

var readerpool = sync.Pool{
	New: func() any {
		return &reader{}
	},
}

func acquireReader() *reader {
	return readerpool.Get().(*reader)
}

func clone(buf []byte) []byte {
	out := make([]byte, len(buf))
	copy(out, buf)
	return out
}

func (r *reader) Setup(url string, aac bool) error {
	r.req = fasthttp.AcquireRequest()
	r.resp = fasthttp.AcquireResponse()

	r.req.SetRequestURI(url)
	r.req.Header.SetUserAgent(cfg.UserAgent)
	r.req.Header.Set("Accept-Encoding", "gzip, deflate, br, zstd")

	if aac {
		r.client = httpc_aac
	} else {
		r.client = httpc
	}

	err := sc.DoWithRetry(r.client, r.req, r.resp)
	if err != nil {
		return err
	}

	data, err := r.resp.BodyUncompressed()
	if err != nil {
		data = r.resp.Body()
	}

	if r.parts == nil {
		cfg.Log("make() r.parts")
		r.parts = make([][]byte, 0, 16)
	} else {
		cfg.Log(cap(r.parts), len(r.parts))
	}
	if aac {
		// clone needed to mitigate memory skill issues here
		for _, s := range bytes.Split(data, []byte{'\n'}) {
			if len(s) == 0 {
				continue
			}
			if s[0] == '#' {
				if bytes.HasPrefix(s, []byte(`#EXT-X-MAP:URI="`)) {
					r.parts = append(r.parts, clone(s[16:len(s)-1]))
				}

				continue
			}

			r.parts = append(r.parts, clone(s))
		}
	} else {
		for _, s := range bytes.Split(data, []byte{'\n'}) {
			if len(s) == 0 || s[0] == '#' {
				continue
			}

			r.parts = append(r.parts, s)
		}
	}

	return nil
}

func (r *reader) Close() error {
	cfg.Log("closed :D")
	if r.req != nil {
		fasthttp.ReleaseRequest(r.req)
		r.req = nil
	}

	if r.resp != nil {
		fasthttp.ReleaseResponse(r.resp)
		r.resp = nil
	}

	r.client = nil
	r.leftover = nil
	r.index = 0
	r.parts = r.parts[:0]

	readerpool.Put(r)
	return nil
}

// you could prob make this a bit faster by concurrency (make a bunch of workers => make them download the parts => temporarily add them to a map => fully assemble the result => make reader.Read() read out the result as the parts are coming in) but whatever, fine for now
func (r *reader) Read(buf []byte) (n int, err error) {
	if len(r.leftover) != 0 {
		h := len(buf)
		if h > len(r.leftover) {
			h = len(r.leftover)
		}

		n = copy(buf, r.leftover[:h])

		if n > len(r.leftover) {
			r.leftover = r.leftover[:0]
		} else {
			r.leftover = r.leftover[n:]
		}

		if n < len(buf) && r.index == len(r.parts) {
			err = io.EOF
		}

		return
	}

	if r.index == len(r.parts) {
		err = io.EOF
		return
	}

	r.req.SetRequestURIBytes(r.parts[r.index])

	err = sc.DoWithRetry(r.client, r.req, r.resp)
	if err != nil {
		return
	}

	data, err := r.resp.BodyUncompressed()
	if err != nil {
		data = r.resp.Body()
	}

	if len(data) > len(buf) {
		n = copy(buf, data[:len(buf)])
	} else {
		n = copy(buf, data)
	}

	r.leftover = data[n:]
	r.index++

	if n < len(buf) && r.index == len(r.parts) {
		err = io.EOF
	}

	return
}

type collector struct {
	data []byte
}

func (c *collector) Write(data []byte) (n int, err error) {
	c.data = append(c.data, data...)
	return len(data), nil
}

func Load(r fiber.Router) {
	httpc = &fasthttp.HostClient{
		Addr:                cfg.HLSCDN + ":443",
		IsTLS:               true,
		DialDualStack:       true,
		Dial:                (&fasthttp.TCPDialer{DNSCacheDuration: cfg.DNSCacheTTL}).Dial,
		MaxIdleConnDuration: 1<<63 - 1,
	}

	httpc_aac = &fasthttp.HostClient{
		Addr:                cfg.HLSAACCDN + ":443",
		IsTLS:               true,
		DialDualStack:       true,
		Dial:                (&fasthttp.TCPDialer{DNSCacheDuration: cfg.DNSCacheTTL}).Dial,
		MaxIdleConnDuration: 1<<63 - 1,
	}

	httpc_image = &fasthttp.HostClient{
		Addr:                cfg.ImageCDN + ":443",
		IsTLS:               true,
		DialDualStack:       true,
		Dial:                (&fasthttp.TCPDialer{DNSCacheDuration: cfg.DNSCacheTTL}).Dial,
		MaxIdleConnDuration: 1<<63 - 1,
		StreamResponseBody:  true,
	}

	r.Get("/_/restream/:author/:track", func(c *fiber.Ctx) error {
		p, err := preferences.Get(c)
		if err != nil {
			return err
		}
		p.ProxyImages = &cfg.False
		p.ProxyStreams = &cfg.False

		cid, err := sc.GetClientID()
		if err != nil {
			return err
		}

		t, err := sc.GetTrack(cid, c.Params("author")+"/"+c.Params("track"))
		if err != nil {
			return err
		}

		var isDownload = c.Query("metadata") == "true"
		var quality *string
		if isDownload {
			quality = p.DownloadAudio
		} else {
			quality = p.RestreamAudio
		}

		tr, audio := t.Media.SelectCompatible(*quality, true)
		if tr == nil {
			return fiber.ErrExpectationFailed
		}

		u, err := tr.GetStream(cid, p, t.Authorization)
		if err != nil {
			return err
		}

		c.Set("Content-Type", tr.Format.MimeType)
		c.Set("Cache-Control", cfg.RestreamCacheControl)

		if isDownload {
			switch audio {
			case cfg.AudioMP3:
				r := acquireReader()
				if err := r.Setup(u, false); err != nil {
					return err
				}

				tag := id3v2.NewEmptyTag()

				tag.SetArtist(t.Author.Username)
				if t.Genre != "" {
					tag.SetGenre(t.Genre)
				}

				tag.SetTitle(t.Title)

				if t.Artwork != "" {
					data, mime, err := t.DownloadImage()
					if err != nil {
						return err
					}

					tag.AddAttachedPicture(id3v2.PictureFrame{MimeType: mime, Picture: data, PictureType: id3v2.PTFrontCover, Encoding: id3v2.EncodingUTF8})
				}

				var col collector
				tag.WriteTo(&col)
				r.leftover = col.data

				// id3 is quite flexible and the files streamed by soundcloud don't have it so its easy to restream the stuff like this
				return c.SendStream(r)

			case cfg.AudioOpus:
				req := fasthttp.AcquireRequest()
				defer fasthttp.ReleaseRequest(req)

				req.SetRequestURI(u)
				req.Header.SetUserAgent(cfg.UserAgent)
				req.Header.Set("Accept-Encoding", "gzip, deflate, br, zstd")

				resp := fasthttp.AcquireResponse()
				defer fasthttp.ReleaseResponse(resp)

				err = sc.DoWithRetry(httpc, req, resp)
				if err != nil {
					return err
				}

				data, err := resp.BodyUncompressed()
				if err != nil {
					data = resp.Body()
				}

				parts := make([][]byte, 0, 16)
				for _, s := range bytes.Split(data, []byte{'\n'}) {
					if len(s) == 0 || s[0] == '#' {
						continue
					}

					parts = append(parts, s)
				}

				result := []byte{}

				for _, part := range parts {
					req.SetRequestURIBytes(part)

					err = sc.DoWithRetry(httpc, req, resp)
					if err != nil {
						return err
					}

					data, err = resp.BodyUncompressed()
					if err != nil {
						data = resp.Body()
					}

					result = append(result, data...)
				}

				tag, err := oggmeta.ReadOGG(bytes.NewReader(result))
				if err != nil {
					return err
				}

				tag.SetArtist(t.Author.Username)
				if t.Genre != "" {
					tag.SetGenre(t.Genre)
				}

				tag.SetTitle(t.Title)

				if t.Artwork != "" {
					req.SetRequestURI(t.Artwork)
					req.Header.Del("Accept-Encoding")

					err := sc.DoWithRetry(httpc_image, req, resp)
					if err != nil {
						return err
					}

					defer resp.CloseBodyStream()
					parsed, err := jpeg.Decode(resp.BodyStream())
					if err != nil {
						return err
					}

					tag.SetCoverArt(&parsed)
				}

				return tag.Save(c)
			case cfg.AudioAAC:
				req := fasthttp.AcquireRequest()
				defer fasthttp.ReleaseRequest(req)

				req.SetRequestURI(u)
				req.Header.SetUserAgent(cfg.UserAgent)
				req.Header.Set("Accept-Encoding", "gzip, deflate, br, zstd")

				resp := fasthttp.AcquireResponse()
				defer fasthttp.ReleaseResponse(resp)

				err = sc.DoWithRetry(httpc_aac, req, resp)
				if err != nil {
					return err
				}

				data, err := resp.BodyUncompressed()
				if err != nil {
					data = resp.Body()
				}

				parts := make([][]byte, 0, 16)
				// clone needed to mitigate memory skill issues here
				for _, s := range bytes.Split(data, []byte{'\n'}) {
					if len(s) == 0 {
						continue
					}
					if s[0] == '#' {
						if bytes.HasPrefix(s, []byte(`#EXT-X-MAP:URI="`)) {
							parts = append(parts, clone(s[16:len(s)-1]))
						}

						continue
					}

					parts = append(parts, clone(s))
				}

				result := []byte{}
				for _, part := range parts {
					req.SetRequestURIBytes(part)

					err = sc.DoWithRetry(httpc_aac, req, resp)
					if err != nil {
						return err
					}

					data, err = resp.BodyUncompressed()
					if err != nil {
						data = resp.Body()
					}

					result = append(result, data...)
				}

				tag, err := mp4meta.ReadMP4(bytes.NewReader(result))
				if err != nil {
					return err
				}

				tag.SetArtist(t.Author.Username)
				if t.Genre != "" {
					tag.SetGenre(t.Genre)
				}

				tag.SetTitle(t.Title)

				if t.Artwork != "" {
					req.SetRequestURI(t.Artwork)
					req.Header.Del("Accept-Encoding")

					err := sc.DoWithRetry(httpc_image, req, resp)
					if err != nil {
						return err
					}

					defer resp.CloseBodyStream()
					parsed, err := jpeg.Decode(resp.BodyStream())
					if err != nil {
						return err
					}

					tag.SetCoverArt(&parsed)
				}

				return tag.Save(c)
			}
		}

		r := acquireReader()
		if err := r.Setup(u, audio == cfg.AudioAAC); err != nil {
			return err
		}

		return c.SendStream(r)
	})
}