WIP: Четвертый день, четвертая задача

2 files changed, 241 insertions, 0 deletions

diff --git a/day4/task4/client.py b/day4/task4/client.py
new file mode 100644
index 0000000..33ea084
--- /dev/null
+++ b/day4/task4/client.py
@@ -0,0 +1,131 @@
+import socket
+from time import sleep
+import struct
+import json
+import shelve
+
+
+def pack_data(data):
+    encoded = data.encode()
+    return struct.pack('I', len(encoded)) + encoded
+
+
+def prepare_data(data):
+    cmd, args = data.split(' ', maxsplit=1)
+
+    if cmd == 'get':
+        return json.dumps({'method': 'get', 'path': args})
+
+    elif cmd == 'cp':
+        paths = args.split()
+        if len(paths) != 2:
+            raise ValueError('Неверное количество путей в параметрах.')
+        src, dest = args.split()
+        if src not in db:
+            return json.dumps({'method': 'get_cp', 'path': src})
+        with open(dest, 'wb') as f:
+            f.write(db[src])
+
+    else:
+        raise ValueError('Команда не распознана')
+
+
+def parse_response(data):
+    return json.loads(data.decode())
+
+
+def get_response(connection):
+    buffer = b''
+    while len(buffer) < DATATYPE_SIZE:
+        data = connection.recv(DATATYPE_SIZE - len(buffer))
+        if not data:
+            raise ConnectionError('Connection was closed')
+
+        buffer += data
+
+    size_packed, buffer = buffer[:DATATYPE_SIZE], buffer[DATATYPE_SIZE:]
+    if not size_packed:
+        raise ConnectionError('Connection was closed')
+
+    (size,) = struct.unpack('I', size_packed)
+    data = connection.recv(size - len(buffer))
+    return parse_response(buffer + data)
+
+
+def download_file(filesize, connection):
+    data = b''
+    count = 0
+    while count < filesize:
+        (size,) = struct.unpack('I', connection.recv(DATATYPE_SIZE))
+        data += connection.recv(size)
+        count += size
+
+    return data
+
+
+def handle_response(data, connection):
+    if data['status'] == 0:
+        print(f'Загружаем файл размером {data["size"]} байт...')
+        file_data = download_file(data['size'], connection)
+        db[data['path']] = file_data
+        print('Загрузка завершена')
+
+    elif data['status'] == 1:
+        print(data['reason'])
+
+    elif data['status'] == 2:
+        print('Неизвестная ошибка:')
+        print(data['reason'])
+
+
+def try_connect():
+    cnt = 0
+    sock = socket.socket()
+    while cnt < 10:
+        try:
+            cnt += 1
+            sock.connect(ADDR)
+
+        except ConnectionRefusedError:
+            print('Не удалось подключиться к серверу. Следующая попытка через 3 секунды...')
+            sleep(3)
+
+        else:
+            return sock
+
+    else:
+        print('Не удалось подключиться к серверу через 10 попыток.\nОстанавливаемся...')
+        sock.close()
+        return
+
+
+HOST, PORT = ADDR = 'localhost', 6000
+DATATYPE_SIZE = 4  # int
+
+sock = try_connect()
+if sock is None:
+    quit()
+
+
+db = shelve.open('backdoor.db')
+
+while True:
+    try:
+        data = input('Введите команду:\n')
+        data = prepare_data(data)
+        if data is None:
+            continue
+
+    except KeyboardInterrupt:
+        break
+
+    except ValueError as err:
+        print(err)
+
+    else:
+        packet = pack_data(data)
+        sock.sendall(packet)
+        response = get_response(sock)
+        handle_response(response, sock)
+
+sock.close()
diff --git a/day4/task4/server.py b/day4/task4/server.py
new file mode 100644
index 0000000..980eebc
--- /dev/null
+++ b/day4/task4/server.py
@@ -0,0 +1,110 @@
+import socket
+import struct
+import json
+
+
+def pack_str(data: str):
+    encoded = data.encode()
+    return struct.pack('I', len(encoded)) + encoded
+
+
+def pack_bytes(data: bytes):
+    return struct.pack('I', len(data)) + data
+
+
+def handle_request(data, connection):
+    request = json.loads(data)
+
+    # Хотя метод только один, но все равно лучше
+    # сразу написать расширяемое приложение
+    if request['method'] == 'get':
+        path = request['path']
+
+        try:
+            with open(path, 'rb') as f:
+                file_data = f.read()
+
+        except FileNotFoundError:
+            header = json.dumps({'status': 1, 'reason': 'Файл не найден'})
+            connection.sendall(pack_str(header))
+
+        except PermissionError:
+            header = json.dumps({'status': 1, 'reason': 'Файл не доступен для чтения'})
+            connection.sendall(pack_str(header))
+
+        # Я знаю, что это плохо, но сервер не должен падать,
+        # а других ошибок я не смог вспомнить
+        except Exception as e:
+            header = json.dumps({'status': 2, 'reason': str(e)})
+            connection.sendall(pack_str(header))
+
+        else:
+            length = len(file_data)
+            header = json.dumps({'status': 0, 'size': length, 'path': request['path']})
+            connection.sendall(pack_str(header))
+            i = 0
+            while i < length:
+                packet = pack_bytes(file_data[i: i + CHUNK_SIZE])
+                connection.sendall(packet)
+                i += CHUNK_SIZE
+
+
+def get_data(connection):
+    buffer = b''
+    while len(buffer) < 4:
+        data = connection.recv(4 - len(buffer))
+        if not data:
+            raise ConnectionError('Connection was closed')
+
+        buffer += data
+
+    size_packed, buffer = buffer[:4], buffer[4:]
+    if not size_packed:
+        raise ConnectionError('Connection was closed')
+
+    (size,) = struct.unpack('I', size_packed)
+    data = connection.recv(size - len(buffer))
+    return buffer + data
+
+
+def handle_connection(connection, address):
+    while True:
+        try:
+            data = get_data(connection)
+
+        except ConnectionResetError:
+            print(f'Connection with {address[0]} was unexpectedly closed')
+            break
+
+        except ConnectionError:
+            print(f'Connection with {address[0]} was ended')
+            break
+
+        except KeyboardInterrupt:
+            raise KeyboardInterrupt()
+
+        else:
+            if not data:
+                print(f'Connection with {address[0]} was ended')
+                break
+            handle_request(data.decode(), connection)
+
+
+HOST, PORT = ADDR = '0.0.0.0', 6000
+CHUNK_SIZE = 4096
+sock = socket.socket()
+sock.bind(ADDR)
+sock.listen(5)
+
+while True:
+    print('Listening for new connections...')
+    try:
+        connection, address = sock.accept()
+        print(f'Got a connection from {address[0]}')
+        handle_connection(connection, address)
+
+    except KeyboardInterrupt:
+        print('Stopping server...')
+        sock.close()
+        print('Server stopped')
+        break