UnBili

/*
 * This is free and unencumbered software released into the public domain.
 * 
 * Anyone is free to copy, modify, publish, use, compile, sell, or
 * distribute this software, either in source code form or as a compiled
 * binary, for any purpose, commercial or non-commercial, and by any
 * means.
 * 
 * In jurisdictions that recognize copyright laws, the author or authors
 * of this software dedicate any and all copyright interest in the
 * software to the public domain. We make this dedication for the benefit
 * of the public at large and to the detriment of our heirs and
 * successors. We intend this dedication to be an overt act of
 * relinquishment in perpetuity of all present and future rights to this
 * software under copyright law.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 * 
 * For more information, please refer to <http://unlicense.org/>
 */

using System;
using System.IO;
using System.IO.Compression;
using System.Net;
using System.Security.Cryptography;
using System.Text;
using System.Text.RegularExpressions;

namespace UnBili
{
    class Program
    {
        const string UserAgent = "Mozilla / 5.0(Windows NT 6.1; WOW64; rv:40.0) Gecko/20100101 Firefox/40.1";

        const string AppKey = "6f90a59ac58a4123";
        const string BiliKey = "0bfd84cc3940035173f35e6777508326";

        static void Main(string[] args)
        {
            Console.WriteLine("Bilibili Stream URL generation test by gdkchan");
            Console.WriteLine("Enter a video URL to extract the Stream:");

            string URL = Console.ReadLine();

            Console.WriteLine(string.Empty);

            Console.WriteLine("Trying to download the webpage...");

            string HTML = HttpGetGZip(URL);
            string CId = Regex.Match(HTML, "cid=([0-9]*)").Groups[1].Value;

            //Here we create the JSON URL
            //We need to generate a signature based on some parameters (see GenSign function for details)
            string[] Params = new string[6];

            Params[0] = "cid=" + CId;
            Params[1] = "appkey=" + AppKey;
            Params[2] = "otype=json";
            Params[3] = "type=mp4";
            Params[4] = "quality=2";
            Params[5] = "sign=" + GenSign(CId);

            string JSONURL = "http://interface.bilibili.com/playurl?" + string.Join("&", Params);

            Console.WriteLine("Trying to download JSON from \"" + JSONURL + "\"...");
            Console.WriteLine(string.Empty);

            string JSON = HttpGet(JSONURL);

            //Extract all URLs from the JSON
            MatchCollection URLs = Regex.Matches(JSON, "https?://[^\"]*");

            if (URLs.Count > 0)
            {
                Console.ForegroundColor = ConsoleColor.White;
                Console.WriteLine("URLs:");
                Console.ResetColor();

                foreach (Match StreamURL in URLs)
                {
                    Console.WriteLine(StreamURL.Value);
                }
            }
            else
            {
                //If we couldn't extract URLs then something is broken, show the returned message
                Console.WriteLine("Can't extract, see JSON below:" + Environment.NewLine + JSON);
            }

            Console.WriteLine(string.Empty);
            Console.WriteLine("Press any key to exit");

            Console.ReadKey();
        }

        static string GenSign(string ContentId)
        {
            //Generates the Signature from a given Video CId
            /*
             * Example of a signature before being hashed:
             * appkey=6f90a59ac58a4123&cid=9388980&otype=json&quality=2&type=mp40bfd84cc3940035173f35e6777508326
             * Both keys are constant for a given Player version. When the Player version changes, the base values
             * for generating the keys or the primitives themselves may change.
             */
            string[] Params = new string[5];

            Params[0] = "appkey=" + AppKey;
            Params[1] = "cid=" + ContentId;
            Params[2] = "otype=json";
            Params[3] = "quality=2";
            Params[4] = "type=mp4";

            string BaseSign = string.Join("&", Params) + BiliKey;
            string Signature = GetMD5(BaseSign);

            return Signature;
        }

        #region "Hash Utils"
        static string GetMD5(string Input)
        {
            //Calculates the MD5 of a Input string
            using (MD5 Hash = MD5.Create())
            {
                //Compute the MD5 Hash of the String on a Byte Array
                byte[] Hashed = Hash.ComputeHash(Encoding.ASCII.GetBytes(Input));

                //Convert Byte Array to a Hex String and returns it
                StringBuilder Output = new StringBuilder();
                foreach (byte HB in Hashed) Output.Append(HB.ToString("X2"));
                return Output.ToString().ToLowerInvariant();
            }
        }
        #endregion

        #region "HTTP Utils"
        private static string HttpGetGZip(string URL)
        {
            //This just downloads a Webpage using HTTP Get and the Firefox User Agent
            WebRequest Request = WebRequest.Create(URL);
            ((HttpWebRequest)Request).UserAgent = UserAgent;

            //Note: The page is GZip compressed, so we need to decompress it first
            WebResponse Response = Request.GetResponse();
            using (GZipStream Reader = new GZipStream(Response.GetResponseStream(), CompressionMode.Decompress))
            {
                using (MemoryStream Output = new MemoryStream())
                {
                    byte[] Buffer = new byte[0x1000]; //4KiB Buffer
                    int Length = 0;

                    while ((Length = Reader.Read(Buffer, 0, Buffer.Length)) > 0)
                    {
                        Output.Write(Buffer, 0, Length);
                    }

                    return Encoding.UTF8.GetString(Output.ToArray());
                }
            }
        }

        private static string HttpGet(string URL)
        {
            //Same thing of the function above, but without the GZip compression
            WebRequest Request = WebRequest.Create(URL);
            ((HttpWebRequest)Request).UserAgent = UserAgent;

            WebResponse Response = Request.GetResponse();
            StreamReader Reader = new StreamReader(Response.GetResponseStream());

            return Reader.ReadToEnd();
        }
        #endregion
    }
}