From aa9d0ed9292b3432da0fe4a4078cfb97a7a21aec Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=A0=D0=BE=D0=BC=D0=B0=D0=BD=20=D0=91=D0=BE=D1=80=D0=BE?=
 =?UTF-8?q?=D0=B4=D0=B8=D0=BD?= <roman@ukamnya.ru>
Date: Fri, 5 Apr 2019 09:50:06 +0300
Subject: [PATCH] stream and channel complete

---
 mods/stream.py | 65 ++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 61 insertions(+), 4 deletions(-)

diff --git a/mods/stream.py b/mods/stream.py
index aec211a..60d89fd 100644
--- a/mods/stream.py
+++ b/mods/stream.py
@@ -5,6 +5,11 @@ from uuid import uuid4
 import datetime, io
 import threading
 import time
+from struct import Struct
+try:
+    import zlib
+except:
+    zlib = None
 
 peers = {}
 
@@ -26,6 +31,7 @@ PACKET_TYPE_CONFIRM_RECV = 0xa1
 PACKET_TYPE_GOODBUY = 0xff
 
 class InvalidPacket(Exception): pass
+class OldPacket(Exception): pass
 
 def pickle_data(data):
     return pickle.dumps(data, protocol=4)
@@ -154,7 +160,7 @@ class Peer:
     def check_received_packet(self, packet):
         if self.last_received_packet_num_reset_time:
             if self.last_received_packet_num_reset_time > packet.reset_timestamp:
-                raise EOFError('packet from past')
+                raise OldPacket('packet from past')
             elif self.last_received_packet_num_reset_time < packet.reset_timestamp:
                 self.last_received_packet_num_reset_time = packet.reset_timestamp
             if (self.last_received_packet_num + 1) != packet.num:
@@ -206,11 +212,14 @@ class Peer:
             ############################################
             else:
                 if packet.type == PACKET_TYPE_PACKET:
+                    try:
+                        self.check_received_packet(packet)
+                    except OldPacket:
+                        return
                     try:
                         raw = self.my_key.decrypt_raw(packet.data)
                     except:
                         raise EOFError('decrypt packet error')
-                    self.check_received_packet(packet)
                     self.put_block(raw)
                 else:
                     raise EOFError('connection lost')
@@ -248,7 +257,6 @@ udpserver_thread = threading.Thread(target=udpserver.serve_forever)
 udpserver_thread.start()
 
 class EncryptedUDPStream:
-    MAX_IO_CHUNK = 8000
     def __init__(self, sock, peer_addr):
         self.peer_addr = peer_addr
         self.sock = sock
@@ -280,7 +288,7 @@ class EncryptedUDPStream:
         except:
             self.close()
             raise EOFError
-    def read(self, count):
+    def read(self):
         try:
             buf = peers[self.peer_addr].get_next_block()
         except:
@@ -292,4 +300,53 @@ class EncryptedUDPStream:
         except:
             raise EOFError
 
+class Channel(object):
+    MAX_IO_CHUNK = 8000
+    COMPRESSION_THRESHOLD = 3000
+    COMPRESSION_LEVEL = 1
+    FRAME_HEADER = Struct("!LB")
+    FLUSHER = b'\n'
+    __slots__ = ["stream", "compress"]
 
+    def __init__(self, stream, compress = True):
+        self.stream = stream
+        if not zlib:
+            compress = False
+        self.compress = compress
+    def close(self):
+        self.stream.close()
+
+    @property
+    def closed(self):
+        return self.stream.closed
+    def fileno(self):
+        return self.stream.fileno()
+
+    def poll(self, timeout):
+        return self.stream.poll(timeout)
+
+    def recv(self):
+        header = self.stream.read()
+        if len(header) != self.FRAME_HEADER.size:
+            raise EOFError('CHANNEL: Not a header received')
+        length, compressed = self.FRAME_HEADER.unpack(header)
+        block_len = length + len(self.FLUSHER)
+        full_block = b''.join((self.stream.read() for x in range(0, block_len, self.MAX_IO_CHUNK)))
+        if len(full_block) != block_len:
+            raise EOFError('CHANNEL: Received block with wrong size')
+        data = full_block[:-len(self.FLUSHER)]
+        if compressed:
+            data = zlib.decompress(data)
+        return data
+
+    def send(self, data):
+        if self.compress and len(data) > self.COMPRESSION_THRESHOLD:
+            compressed = 1
+            data = zlib.compress(data, self.COMPRESSION_LEVEL)
+        else:
+            compressed = 0
+        header = self.FRAME_HEADER.pack(len(data), compressed)
+        self.stream.write(header)
+        buf = data + self.FLUSHER
+        for chunk_start in range(0, len(buf), self.MAX_IO_CHUNK):
+            self.stream.write(buf[chunk_start:self.MAX_IO_CHUNK])