From f6035f5304b718c6b0df6a629a8021d1fe0327ea Mon Sep 17 00:00:00 2001
From: Sourav <70096119+ydavs@users.noreply.github.com>
Date: Tue, 23 Aug 2022 06:29:52 +0000
Subject: [PATCH 1/3] Fixed Issue. Issue : Header length not consumed for
 KeepAlive messages which eventually leads to an infinite loop.

---
 pieces/protocol.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/pieces/protocol.py b/pieces/protocol.py
index 51833e5..3f55a66 100644
--- a/pieces/protocol.py
+++ b/pieces/protocol.py
@@ -316,6 +316,9 @@ def parse(self):
             message_length = struct.unpack('>I', self.buffer[0:4])[0]
 
             if message_length == 0:
+                logging.debug('Got a KeepAlive message')
+                # Call consume 
+                self.buffer = self.buffer[header_length + message_length:]
                 return KeepAlive()
 
             if len(self.buffer) >= message_length:

From cd05c8c2cbcb79be0e8bae1d726295188f8611c2 Mon Sep 17 00:00:00 2001
From: Sourav <70096119+ydavs@users.noreply.github.com>
Date: Tue, 23 Aug 2022 09:08:18 +0000
Subject: [PATCH 2/3] Fixed case for peers that don't send BitField

---
 pieces/client.py   | 17 ++++++++++++++++-
 pieces/protocol.py | 16 ++++++++++++----
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/pieces/client.py b/pieces/client.py
index baa388e..1663dbb 100644
--- a/pieces/client.py
+++ b/pieces/client.py
@@ -23,6 +23,7 @@
 from asyncio import Queue
 from collections import namedtuple, defaultdict
 from hashlib import sha1
+import bitstring
 
 from pieces.protocol import PeerConnection, REQUEST_SIZE
 from pieces.tracker import Tracker
@@ -322,6 +323,13 @@ def bytes_uploaded(self) -> int:
         # TODO Add support for sending data
         return 0
 
+    def add_peer_without_bitfield(self, peer_id):
+        """ 
+        Adds a peer without requiring a bitfield(Note sending a bitfield is optional.).
+        """
+        bitfield = bitstring.BitArray(int=0, length=self.total_pieces)
+        self.peers[peer_id] = bitfield
+
     def add_peer(self, peer_id, bitfield):
         """
         Adds a peer and the bitfield representing the pieces the peer has.
@@ -369,7 +377,11 @@ def next_request(self, peer_id) -> Block:
         if not block:
             block = self._next_ongoing(peer_id)
             if not block:
-                block = self._get_rarest_piece(peer_id).next_request()
+                piece = self._get_rarest_piece(peer_id)
+                if piece == None:
+                    return None
+                else:
+                    block = piece.next_request()
         return block
 
     def block_received(self, peer_id, piece_index, block_offset, data):
@@ -468,6 +480,8 @@ def _get_rarest_piece(self, peer_id):
                 if self.peers[p][piece.index]:
                     piece_count[piece] += 1
 
+        if len(piece_count) == 0:
+            return None
         rarest_piece = min(piece_count, key=lambda p: piece_count[p])
         self.missing_pieces.remove(rarest_piece)
         self.ongoing_pieces.append(rarest_piece)
@@ -499,3 +513,4 @@ def _write(self, piece):
         pos = piece.index * self.torrent.piece_length
         os.lseek(self.fd, pos, os.SEEK_SET)
         os.write(self.fd, piece.data)
+    
\ No newline at end of file
diff --git a/pieces/protocol.py b/pieces/protocol.py
index 3f55a66..f8f0460 100644
--- a/pieces/protocol.py
+++ b/pieces/protocol.py
@@ -105,6 +105,9 @@ async def _start(self):
                 # Sending BitField is optional and not needed when client does
                 # not have any pieces. Thus we do not send any bitfield message
 
+                # Some peers don't sent any BitField and rely on Have messages.
+                # Thus we add a peer wihout any BitField.
+                self.piece_manager.add_peer_without_bitfield(self.remote_id)
                 # The default state for a connection is that peer is not
                 # interested and we are choked
                 self.my_state.append('choked')
@@ -116,6 +119,7 @@ async def _start(self):
                 # Start reading responses as a stream of messages for as
                 # long as the connection is open and data is transmitted
                 async for message in PeerStreamIterator(self.reader, buffer):
+                    logging.debug('Message received is of type {}'.format(type(message)))
                     if 'stopped' in self.my_state:
                         break
                     if type(message) is BitField:
@@ -154,9 +158,10 @@ async def _start(self):
                     if 'choked' not in self.my_state:
                         if 'interested' in self.my_state:
                             if 'pending_request' not in self.my_state:
-                                self.my_state.append('pending_request')
-                                await self._request_piece()
-
+                                chk = await self._request_piece()
+                                if chk:
+                                    self.my_state.append('pending_request')
+                                
             except ProtocolError as e:
                 logging.exception('Protocol error')
             except (ConnectionRefusedError, TimeoutError):
@@ -207,6 +212,9 @@ async def _request_piece(self):
 
             self.writer.write(message)
             await self.writer.drain()
+            return True 
+        else:
+            return False
 
     async def _handshake(self):
         """
@@ -321,7 +329,7 @@ def parse(self):
                 self.buffer = self.buffer[header_length + message_length:]
                 return KeepAlive()
 
-            if len(self.buffer) >= message_length:
+            if len(self.buffer) >= message_length+header_length:
                 message_id = struct.unpack('>b', self.buffer[4:5])[0]
 
                 def _consume():

From 937c2c9184c225cb1e07d7a4c4c7121de08dad98 Mon Sep 17 00:00:00 2001
From: Sourav <70096119+ydavs@users.noreply.github.com>
Date: Thu, 25 Aug 2022 11:44:38 +0000
Subject: [PATCH 3/3] Added support for multi-file torrents. Fixed Issue.

Re-requesting failed because PendingRequest implemented as namedTuple(immutable), changed it to dict.
---
 pieces/cli.py     |  2 +-
 pieces/client.py  | 58 ++++++++++++++++++++++++++++++++---------------
 pieces/torrent.py | 43 +++++++++++++++++++++++++++--------
 pieces/tracker.py | 19 +++-------------
 4 files changed, 77 insertions(+), 45 deletions(-)

diff --git a/pieces/cli.py b/pieces/cli.py
index 0175ed1..192159f 100644
--- a/pieces/cli.py
+++ b/pieces/cli.py
@@ -35,7 +35,7 @@ def main():
 
     args = parser.parse_args()
     if args.verbose:
-        logging.basicConfig(level=logging.INFO)
+        logging.basicConfig(filename='logfile.log', level=logging.INFO)
 
     loop = asyncio.get_event_loop()
     client = TorrentClient(Torrent(args.torrent))
diff --git a/pieces/client.py b/pieces/client.py
index 1663dbb..1d7f5a9 100644
--- a/pieces/client.py
+++ b/pieces/client.py
@@ -70,11 +70,11 @@ async def start(self):
         if the download is aborted this method will complete.
         """
         self.peers = [PeerConnection(self.available_peers,
-                                     self.tracker.torrent.info_hash,
-                                     self.tracker.peer_id,
-                                     self.piece_manager,
-                                     self._on_block_retrieved)
-                      for _ in range(MAX_PEER_CONNECTIONS)]
+                                    self.tracker.torrent.info_hash,
+                                    self.tracker.peer_id,
+                                    self.piece_manager,
+                                    self._on_block_retrieved)
+                        for _ in range(MAX_PEER_CONNECTIONS)]
 
         # The time we last made an announce call (timestamp)
         previous = None
@@ -83,6 +83,7 @@ async def start(self):
 
         while True:
             if self.piece_manager.complete:
+                self.piece_manager._organize_files()
                 logging.info('Torrent fully downloaded!')
                 break
             if self.abort:
@@ -96,6 +97,7 @@ async def start(self):
                     uploaded=self.piece_manager.bytes_uploaded,
                     downloaded=self.piece_manager.bytes_downloaded)
 
+                logging.debug(response)
                 if response:
                     previous = current
                     interval = response.interval
@@ -234,9 +236,6 @@ def data(self):
         blocks_data = [b.data for b in retrieved]
         return b''.join(blocks_data)
 
-# The type used for keeping track of pending request that can be re-issued
-PendingRequest = namedtuple('PendingRequest', ['block', 'added'])
-
 
 class PieceManager:
     """
@@ -401,8 +400,8 @@ def block_received(self, peer_id, piece_index, block_offset, data):
 
         # Remove from pending requests
         for index, request in enumerate(self.pending_blocks):
-            if request.block.piece == piece_index and \
-               request.block.offset == block_offset:
+            if request['block'].piece == piece_index and \
+               request['block'].offset == block_offset:
                 del self.pending_blocks[index]
                 break
 
@@ -440,15 +439,15 @@ def _expired_requests(self, peer_id) -> Block:
         """
         current = int(round(time.time() * 1000))
         for request in self.pending_blocks:
-            if self.peers[peer_id][request.block.piece]:
-                if request.added + self.max_pending_time < current:
+            if self.peers[peer_id][request['block'].piece]:
+                if request['added'] + self.max_pending_time < current:
                     logging.info('Re-requesting block {block} for '
                                  'piece {piece}'.format(
-                                    block=request.block.offset,
-                                    piece=request.block.piece))
+                                    block=request['block'].offset,
+                                    piece=request['block'].piece))
                     # Reset expiration timer
-                    request.added = current
-                    return request.block
+                    request['added'] = current
+                    return request['block']
         return None
 
     def _next_ongoing(self, peer_id) -> Block:
@@ -462,7 +461,7 @@ def _next_ongoing(self, peer_id) -> Block:
                 block = piece.next_request()
                 if block:
                     self.pending_blocks.append(
-                        PendingRequest(block, int(round(time.time() * 1000))))
+                        {'block':block, 'added':int(round(time.time()*1000))})
                     return block
         return None
 
@@ -513,4 +512,27 @@ def _write(self, piece):
         pos = piece.index * self.torrent.piece_length
         os.lseek(self.fd, pos, os.SEEK_SET)
         os.write(self.fd, piece.data)
-    
\ No newline at end of file
+
+    def _organize_files(self):
+        """ 
+        Organize the file strucuture from a single file to as provided in meta_info. 
+        """
+        if not self.torrent.multi_file: 
+            return
+        #if not self.complete: 
+        #    raise RuntimeError('organize_files called before completing download!')
+        pos = 0 
+        for file in self.torrent.files: 
+            os.lseek(self.fd, pos, os.SEEK_SET)
+            buffer = os.read(self.fd, file.length) 
+            pos += file.length
+
+            os.makedirs(os.path.dirname(file.path), exist_ok=True)
+            tmp_fd = os.open(file.path,  os.O_RDWR | os.O_CREAT)
+            os.write(tmp_fd, buffer) 
+            os.close(tmp_fd) 
+
+        # Remove the redundant tmp files 
+        os.remove(self.torrent.output_file)
+
+        return 
\ No newline at end of file
diff --git a/pieces/torrent.py b/pieces/torrent.py
index 6945e9f..27b5354 100644
--- a/pieces/torrent.py
+++ b/pieces/torrent.py
@@ -17,11 +17,12 @@
 
 from hashlib import sha1
 from collections import namedtuple
+import os
 
 from . import bencoding
 
 # Represents the files within the torrent (i.e. the files to write to disk)
-TorrentFile = namedtuple('TorrentFile', ['name', 'length'])
+TorrentFile = namedtuple('TorrentFile', ['path', 'length'])
 
 
 class Torrent:
@@ -47,12 +48,18 @@ def _identify_files(self):
         Identifies the files included in this torrent
         """
         if self.multi_file:
-            # TODO Add support for multi-file torrents
-            raise RuntimeError('Multi-file torrents is not supported!')
-        self.files.append(
-            TorrentFile(
-                self.meta_info[b'info'][b'name'].decode('utf-8'),
-                self.meta_info[b'info'][b'length']))
+            name = self.meta_info[b'info'][b'name'].decode('utf-8')
+            if not os.path.exists(name):
+                os.mkdir(name); 
+            for file in self.meta_info[b'info'][b'files']:
+                curr_path = (b'/'.join(file[b'path'])).decode('utf-8')
+                curr_path = os.path.join(self.meta_info[b'info'][b'name'].decode('utf-8'), curr_path)
+                self.files.append(TorrentFile(curr_path, file[b'length'])) 
+        else:
+            self.files.append(
+                TorrentFile(
+                    self.meta_info[b'info'][b'name'].decode('utf-8'),
+                    self.meta_info[b'info'][b'length']))
 
     @property
     def announce(self) -> str:
@@ -60,6 +67,16 @@ def announce(self) -> str:
         The announce URL to the tracker.
         """
         return self.meta_info[b'announce'].decode('utf-8')
+    
+    @property
+    def announce_list(self) -> list:
+        """ 
+        Returns announce list of trackers. 
+        """
+        if b'announce-list' in self.meta_info.keys():
+            return [[a.decode('utf-8') for a in x] for x in self.meta_info[b'announce-list']]
+        else:
+            return None
 
     @property
     def multi_file(self) -> bool:
@@ -86,8 +103,9 @@ def total_size(self) -> int:
         :return: The total size (in bytes) for this torrent's data.
         """
         if self.multi_file:
-            raise RuntimeError('Multi-file torrents is not supported!')
-        return self.files[0].length
+            return sum(file.length for file in self.files) 
+        else:
+            return self.files[0].length
 
     @property
     def pieces(self):
@@ -106,7 +124,12 @@ def pieces(self):
 
     @property
     def output_file(self):
-        return self.meta_info[b'info'][b'name'].decode('utf-8')
+        if self.multi_file:
+            if not os.path.exists('.pieces_tmp'):
+                os.mkdir('.pieces_tmp')
+            return os.path.join('.pieces_tmp', 'tmp')
+        else:
+            return self.meta_info[b'info'][b'name'].decode('utf-8')
 
     def __str__(self):
         return 'Filename: {0}\n' \
diff --git a/pieces/tracker.py b/pieces/tracker.py
index da81efd..b0ab218 100644
--- a/pieces/tracker.py
+++ b/pieces/tracker.py
@@ -80,6 +80,7 @@ def peers(self):
         # where the peers field is a list of dictionaries and one where all
         # the peers are encoded in a single string
         peers = self.response[b'peers']
+        logging.debug('Type of peers is {0}, and len is {1}'.format(type(peers), len(peers))) 
         if type(peers) == list:
             # TODO Implement support for dictionary peer list
             logging.debug('Dictionary model peers are returned by tracker')
@@ -144,6 +145,8 @@ async def connect(self,
             params['event'] = 'started'
 
         url = self.torrent.announce + '?' + urlencode(params)
+        logging.debug(self.torrent.announce_list)
+        logging.debug(self.torrent.announce) 
         logging.info('Connecting to tracker at: ' + url)
 
         async with self.http_client.get(url) as response:
@@ -171,22 +174,6 @@ def raise_for_error(self, tracker_response):
         except UnicodeDecodeError:
             pass
 
-    def _construct_tracker_parameters(self):
-        """
-        Constructs the URL parameters used when issuing the announce call
-        to the tracker.
-        """
-        return {
-            'info_hash': self.torrent.info_hash,
-            'peer_id': self.peer_id,
-            'port': 6889,
-            # TODO Update stats when communicating with tracker
-            'uploaded': 0,
-            'downloaded': 0,
-            'left': 0,
-            'compact': 1}
-
-
 def _calculate_peer_id():
     """
     Calculate and return a unique Peer ID.