feat(media): download and decrypt media

cmd/download.go

@@ -27,11 +27,24 @@ var downloadCmd = &cobra.Command{
 			for _, song := range album.Songs.Data {
 				media, err := song.GetMediaData()
 				if err != nil {
-					fmt.Fprintf(os.Stderr, "could not fetch media data: %v\n", err)
+					fmt.Fprintf(os.Stderr, "could not get media data: %v\n", err)
+					if err.Error() == "invalid license token" {
+						os.Exit(1)
+					}
 					continue
 				}
 
-				fmt.Println(media)
+				songTitle := song.Title
+				if song.Version != "" {
+					songTitle = fmt.Sprintf("%s %s", song.Title, song.Version)
+				}
+
+				filename := fmt.Sprintf("%s - %s.flac", song.ArtistName, songTitle)
+				err = media.Download(filename, song.ID)
+				if err != nil {
+					fmt.Fprintf(os.Stderr, "could not download song: %v\n", err)
+					continue
+				}
 			}
 		}
 	},

go.mod

@@ -7,4 +7,5 @@ require github.com/spf13/cobra v1.8.1
 require (
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
+	golang.org/x/crypto v0.28.0
 )

go.sum

@@ -6,5 +6,7 @@ github.com/spf13/cobra v1.8.1 h1:e5/vxKd/rZsfSJMUX1agtjeTDf+qv1/JdBF8gg5k9ZM=
 github.com/spf13/cobra v1.8.1/go.mod h1:wHxEcudfqmLYa8iTfL+OuZPbBZkmvliBWKIezN3kD9Y=
 github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
 github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+golang.org/x/crypto v0.28.0 h1:GBDwsMXVQi34v5CCYUm2jkJvu4cbtru2U4TN2PSyQnw=
+golang.org/x/crypto v0.28.0/go.mod h1:rmgy+3RHxRZMyY0jjAJShp2zgEdOqj2AO7U0pYmeQ7U=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

internal/crypto/crypto.go

@@ -0,0 +1,39 @@
+package crypto
+
+import (
+	"crypto/cipher"
+	"crypto/md5"
+	"fmt"
+
+	"golang.org/x/crypto/blowfish"
+)
+
+const (
+	SecretKey = ""
+	IV        = ""
+)
+
+func GetBlowfishKey(songID string) []byte {
+	hash := md5.Sum([]byte(songID))
+	hashHex := fmt.Sprintf("%x", hash)
+
+	key := []byte(SecretKey)
+	for i := 0; i < len(hash); i++ {
+		key[i] = key[i] ^ hashHex[i] ^ hashHex[i+16]
+	}
+
+	return key
+}
+
+func DecryptBlowfish(data, key []byte) ([]byte, error) {
+	block, err := blowfish.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	mode := cipher.NewCBCDecrypter(block, []byte(IV))
+	decrypted := make([]byte, len(data))
+	mode.CryptBlocks(decrypted, data)
+
+	return decrypted, nil
+}

internal/deezer/media.go

@@ -1,5 +1,13 @@
 package deezer
 
+import (
+	"fmt"
+	"net/http"
+	"os"
+
+	"github.com/mathismqn/godeez/internal/crypto"
+)
+
 type Media struct {
 	Errors []MediaError `json:"errors"`
 	Data   []struct {
@@ -25,3 +33,67 @@ type Source struct {
 	URL      string `json:"url"`
 	Provider string `json:"provider"`
 }
+
+const ChunkSize = 2048
+
+func (m *Media) Download(filename, songID string) error {
+	url := m.Data[0].Media[0].Sources[0].URL
+
+	resp, err := http.Get(url)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	file, err := os.Create(filename)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	key := crypto.GetBlowfishKey(songID)
+	buffer := make([]byte, ChunkSize)
+
+	for chunk := 0; ; chunk++ {
+		totalRead := 0
+		for totalRead < ChunkSize {
+			n, err := resp.Body.Read(buffer[totalRead:])
+			if err != nil {
+				if err.Error() == "EOF" {
+					break
+				}
+				return err
+			}
+
+			if n > 0 {
+				totalRead += n
+			}
+		}
+
+		if totalRead == 0 {
+			break
+		}
+
+		if chunk%3 == 0 && totalRead == ChunkSize {
+			buffer, err = crypto.DecryptBlowfish(buffer, key)
+			if err != nil {
+				return err
+			}
+		}
+
+		_, err = file.Write(buffer[:totalRead])
+		if err != nil {
+			return err
+		}
+
+		if totalRead < ChunkSize {
+			break
+		}
+	}
+
+	return nil
+}

internal/deezer/song.go

@@ -12,12 +12,14 @@ type Song struct {
 	ID         string `json:"SNG_ID"`
 	ArtistName string `json:"ART_NAME"`
 	Title      string `json:"SNG_TITLE"`
+	Version    string `json:"VERSION"`
 	TrackToken string `json:"TRACK_TOKEN"`
 }
 
+const LicenseToken = ""
+
 func (s *Song) GetMediaData() (*Media, error) {
-	licenseToken := ""
-	reqBody := fmt.Sprintf(`{"license_token":"%s","media":[{"type":"FULL","formats":[{"cipher":"BF_CBC_STRIPE","format":"FLAC"}]}],"track_tokens":["%s"]}`, licenseToken, s.TrackToken)
+	reqBody := fmt.Sprintf(`{"license_token":"%s","media":[{"type":"FULL","formats":[{"cipher":"BF_CBC_STRIPE","format":"FLAC"}]}],"track_tokens":["%s"]}`, LicenseToken, s.TrackToken)
 
 	resp, err := http.Post("https://media.deezer.com/v1/get_url", "application/json", bytes.NewBuffer([]byte(reqBody)))
 	if err != nil {
@@ -25,6 +27,10 @@ func (s *Song) GetMediaData() (*Media, error) {
 	}
 	defer resp.Body.Close()
 
+	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusBadRequest {
+		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
 	body, _ := io.ReadAll(resp.Body)
 
 	var media Media