feat(media): download and decrypt media

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