/// <summary>
/// 转换 NCM 文件为 Flac/MP3 文件
/// </summary>
/// <param name="filePath">NCM 文件路径</param>
/// <returns>转换状态</returns>
public NCMConverterEnum ProcessFile(string filePath)
{
using (var fs = File.Open(filePath, FileMode.Open))
{
// 校验是否是网易云加密的 NCM 文件
if (NCMExtenstion.ReadInt32(fs) != 0x4e455443)
{
return(NCMConverterEnum.Invalid);
}
if (NCMExtenstion.ReadInt32(fs) != 0x4d414446)
{
return(NCMConverterEnum.Invalid);
}
// 读取密钥
NCMExtenstion.Seek(fs, 2);
var keyBytes = NCMExtenstion.ReadBytes(fs, NCMExtenstion.ReadInt32(fs));
for (int i = 0; i < keyBytes.Length; i++)
{
keyBytes[i] ^= 0x64;
}
// 减去 "neteasecloudmusic" 字符串之后的数据即为密钥数据
var deKeyDataBytes = NCMExtenstion.GetBytesByOffset(NCMExtenstion.DecryptAes128Ecb(Encoding.UTF8.GetBytes(NCMConveterConsts.AesCoreKeyString), keyBytes), 17);
var modifyDataBytes = NCMExtenstion.ReadBytes(fs, NCMExtenstion.ReadInt32(fs));
for (int i = 0; i < modifyDataBytes.Length; i++)
{
modifyDataBytes[i] ^= 0x63;
}
var decryptBase64 = SystemConvert.FromBase64String(Encoding.UTF8.GetString(NCMExtenstion.GetBytesByOffset(modifyDataBytes, 22)));
var decryptModifyDataBytes = NCMExtenstion.DecryptAes128Ecb(Encoding.UTF8.GetBytes(NCMConveterConsts.AesModifyKeyBytes), decryptBase64);
// 获取 NCM 文件的歌曲文件信息 Json
var musicJson = JObject.Parse(Encoding.UTF8.GetString(NCMExtenstion.GetBytesByOffset(decryptModifyDataBytes, 6)));
var fileExtension = musicJson.SelectToken("$.format").Value <string>();
// 跳过 CRC 校验
NCMExtenstion.Seek(fs, 9);
// 跳过专辑图像数据
var imageBytes = new byte[NCMExtenstion.ReadInt32(fs)];
if (imageBytes.Length != 0)
{
fs.Read(imageBytes, 0, imageBytes.Length);
}
var box = NCMExtenstion.BuildKeyBox(deKeyDataBytes);
var n = 0x8000;
using (var outputFile = File.Create(Path.Combine(Path.GetDirectoryName(filePath), $"{Path.GetFileNameWithoutExtension(filePath)}.{fileExtension}")))
{
while (true)
{
var tb = new byte[n];
var result = fs.Read(tb, 0, n);
if (result <= 0)
{
break;
}
for (int i = 0; i < n; i++)
{
var j = (byte)((i + 1) & 0xff);
tb[i] ^= box[box[j] + box[(box[j] + j) & 0xff] & 0xff];
}
outputFile.Write(tb, 0, n);
}
outputFile.Flush();
}
fs.Close();
return(NCMConverterEnum.Success);
}
}
object IParser.Parse(XElement e)
{
string name;
object id;
byte[] content;
Entity entity;
bool templateByDefault;
EnumTreeType treeType;
ParseObject(e, out id, out name);
var fileNameAttribute = e.Attribute("fileName");
if (fileNameAttribute == null)
{
throw new ArgumentException(Message.Get("Xml.NoAttribute", "fileName", e), "e");
}
var typeNameAttribute = e.Attribute("typeName");
if (typeNameAttribute == null)
{
throw new ArgumentException(Message.Get("Xml.NoAttribute", "typeName", e), "e");
}
var typeCodeAttribute = e.Attribute("typeCode");
if (typeCodeAttribute == null)
{
throw new ArgumentException(Message.Get("Xml.NoAttribute", "typeCode", e), "e");
}
var entityIDAttribute = e.Attribute("entityID");
if (entityIDAttribute == null)
{
throw new ArgumentException(Message.Get("Xml.NoAttribute", "entityID", e), "e");
}
entity = Storage.Select <Entity>(entityIDAttribute.Value);
var templateByDefaultAttribute = e.Attribute("templateByDefault");
if (templateByDefaultAttribute == null)
{
throw new ArgumentException(Message.Get("Xml.NoAttribute", "entityID", e), "e");
}
templateByDefault = templateByDefaultAttribute.Value == "1" ? true : false;
var treeTypeIDAttribute = e.Attribute("templateByDefault");
if (treeTypeIDAttribute == null)
{
throw new ArgumentException(Message.Get("Xml.NoAttribute", "entityID", e), "e");
}
treeType = GetTreeTypeID(e.Attribute("treeTypeID").Value);
List <TemplateField> fields = new List <TemplateField>();
var fieldsElement = e.Element("fields");
if (fieldsElement != null)
{
var fieldElements = fieldsElement.Elements("field");
if (fieldElements.Count() == 0)
{
throw new ArgumentException(Message.Get("Xml.NoElements", "field", e), "e");
}
templateFieldParser = new TemplateFieldParser(entity);
fields = fieldElements.Select(o => templateFieldParser.Parse(o)).ToList();
}
var contentNode = e.Element("content");
if (contentNode == null)
{
throw new ArgumentException(Message.Get("Xml.NoElement", "content", e), "content");
}
try
{
content = Convert.FromBase64String(contentNode.Value);
}
catch
{
#warning Использую ArithmeticException.
throw new ArithmeticException("Не удалось преобразовать тело документа к массиву байт.");
}
var sheetAttribute = e.Attribute("sheet");
Dictionary <string, string> parameters = null;
if (sheetAttribute != null)
{
parameters = new System.Collections.Generic.Dictionary <string, string>();
parameters["sheet"] = sheetAttribute.Value;
}
return(new Template(id, name, entity, fileNameAttribute.Value, typeNameAttribute.Value, typeCodeAttribute.Value, templateByDefault, treeType, content, fields, parameters));
}
