Jackett-Jackett/src/Jackett/Controllers/DownloadController.cs

using System;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;
using System.Threading.Tasks;
using System.Web;
using System.Web.Http;
using BencodeNET.Parsing;
using Jackett.Common.Models.Config;
using Jackett.Common.Services.Interfaces;
using Jackett.Common.Utils;
using NLog;

namespace Jackett.Controllers
{
    [AllowAnonymous]
    [JackettAPINoCache]
    public class DownloadController : ApiController
    {
        private ServerConfig config;
        private Logger logger;
        private IIndexerManagerService indexerService;        
        private IProtectionService protectionService;

        public DownloadController(IIndexerManagerService i, Logger l, IProtectionService ps, ServerConfig serverConfig)
        {
            config = serverConfig;
            logger = l;
            indexerService = i;
            protectionService = ps;
        }

        [HttpGet]
        public async Task<HttpResponseMessage> Download(string indexerID, string path, string jackett_apikey, string file)
        {
            try
            {
                var indexer = indexerService.GetWebIndexer(indexerID);

                if (!indexer.IsConfigured)
                {
                    logger.Warn(string.Format("Rejected a request to {0} which is unconfigured.", indexer.DisplayName));
                    return Request.CreateResponse(HttpStatusCode.Forbidden, "This indexer is not configured.");
                }

                path = Encoding.UTF8.GetString(HttpServerUtility.UrlTokenDecode(path));
                path = protectionService.UnProtect(path);

                if (config.APIKey != jackett_apikey)
                    return new HttpResponseMessage(HttpStatusCode.Unauthorized);

                var target = new Uri(path, UriKind.RelativeOrAbsolute);
                var downloadBytes = await indexer.Download(target);

                // handle magnet URLs
                if (downloadBytes.Length >= 7
                    && downloadBytes[0] == 0x6d // m
                    && downloadBytes[1] == 0x61 // a
                    && downloadBytes[2] == 0x67 // g
                    && downloadBytes[3] == 0x6e // n
                    && downloadBytes[4] == 0x65 // e
                    && downloadBytes[5] == 0x74 // t
                    && downloadBytes[6] == 0x3a // :
                    )
                {
                    var magneturi = Encoding.UTF8.GetString(downloadBytes);
                    var response = Request.CreateResponse(HttpStatusCode.Moved);
                    response.Headers.Location = new Uri(magneturi);
                    return response;
                }

                // This will fix torrents where the keys are not sorted, and thereby not supported by Sonarr.
                byte[] sortedDownloadBytes = null;
                try
                {
                    var parser = new BencodeParser();
                    var torrentDictionary = parser.Parse(downloadBytes);
                    sortedDownloadBytes = torrentDictionary.EncodeAsBytes();
                }
                catch (Exception e)
                {
                    var content = indexer.Encoding.GetString(downloadBytes);
                    logger.Error(content);
                    throw new Exception("BencodeParser failed", e);
                }

                var result = new HttpResponseMessage(HttpStatusCode.OK);
                result.Content = new ByteArrayContent(sortedDownloadBytes);
                result.Content.Headers.ContentType = new MediaTypeHeaderValue("application/x-bittorrent");
                result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
                {
                    FileName = StringUtil.MakeValidFileName(file, '_', false) + ".torrent" // call MakeValidFileName again to avoid any kind of injection attack
                };
                return result;
            }
            catch (Exception e)
            {
                logger.Error(e, "Error downloading " + indexerID + " " + path);
                return new HttpResponseMessage(HttpStatusCode.NotFound);
            }
        }
    }
}