Question

我写了一个简单的WebSocket客户端。我使用了我在SO上找到的代码，这里：How can I send and receive WebSocket messages on the server side?。

我在Python 2.7 TCP端口上使用echo.websocket.org而我的服务器是80。基本上，我认为接收消息时遇到问题。（或者也许发送错了？）

至少我确信握手一切正常，因为我收到了良好的握手响应：

HTTP/1.1 101 Web Socket Protocol Handshake
Access-Control-Allow-Credentials: true
Access-Control-Allow-Headers: content-type
Access-Control-Allow-Headers: authorization
Access-Control-Allow-Headers: x-websocket-extensions
Access-Control-Allow-Headers: x-websocket-version
Access-Control-Allow-Headers: x-websocket-protocol
Access-Control-Allow-Origin: http://example.com
Connection: Upgrade
Date: Tue, 02 May 2017 21:54:31 GMT
Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=
Server: Kaazing Gateway
Upgrade: websocket

我的代码：

#!/usr/bin/env python
import socket

def encode_text_msg_websocket(data):
    bytesFormatted = []
    bytesFormatted.append(129)

    bytesRaw = data.encode()
    bytesLength = len(bytesRaw)

    if bytesLength <= 125:
        bytesFormatted.append(bytesLength)
    elif 126 <= bytesLength <= 65535:
        bytesFormatted.append(126)
        bytesFormatted.append((bytesLength >> 8) & 255)
        bytesFormatted.append(bytesLength & 255)
    else:
        bytesFormatted.append(127)
        bytesFormatted.append((bytesLength >> 56) & 255)
        bytesFormatted.append((bytesLength >> 48) & 255)
        bytesFormatted.append((bytesLength >> 40) & 255)
        bytesFormatted.append((bytesLength >> 32) & 255)
        bytesFormatted.append((bytesLength >> 24) & 255)
        bytesFormatted.append((bytesLength >> 16) & 255)
        bytesFormatted.append((bytesLength >> 8) & 255)
        bytesFormatted.append(bytesLength & 255)

    bytesFormatted = bytes(bytesFormatted)
    bytesFormatted = bytesFormatted + bytesRaw
    return bytesFormatted


def dencode_text_msg_websocket(stringStreamIn):
    byteArray = [ord(character) for character in stringStreamIn]
    datalength = byteArray[1] & 127
    indexFirstMask = 2
    if datalength == 126:
        indexFirstMask = 4
    elif datalength == 127:
        indexFirstMask = 10
    masks = [m for m in byteArray[indexFirstMask: indexFirstMask + 4]]
    indexFirstDataByte = indexFirstMask + 4
    decodedChars = []
    i = indexFirstDataByte
    j = 0
    while i < len(byteArray):
        decodedChars.append(chr(byteArray[i] ^ masks[j % 4]))
        i += 1
        j += 1
    return ''.join(decodedChars)

# connect 
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((socket.gethostbyname('echo.websocket.org'), 80))

# handshake
handshake = 'GET / HTTP/1.1\r\nHost: echo.websocket.org\r\nUpgrade: websocket\r\nConnection: Upgrade\r\nSec-WebSocket-Key: gfhjgfhjfj\r\nOrigin: http://example.com\r\nSec-WebSocket-Protocol: echo\r\n' \
        'Sec-WebSocket-Version: 13\r\n\r\n'
sock.send(handshake)
print sock.recv(1024)

# send test msg
msg = encode_text_msg_websocket('hello world!')
sock.sendall(msg)

# receive it back
response = dencode_text_msg_websocket(sock.recv(1024))
print '--%s--' % response

sock.close()

这里有什么问题？握手后它变得复杂了。

dencode_text_msg_websocket方法返回一个空字符串，但它应该返回我发送给服务器的相同字符串，即hello world!。

我不想使用库（我知道如何使用它们）。问题是关于在没有库的情况下实现同样的事情，仅使用套接字。

我只想向echo.websocket.org server发送消息并收到回复，这就是全部。我不想修改标题，只需构建这个服务器使用的标题。我检查了它们应该如何使用Wireshark，并尝试使用Python构建相同的数据包。

对于以下测试，我使用了我的浏览器：

从服务器到客户端的未屏蔽数据：

从客户端到服务器的屏蔽数据：

Answer 1

收到https://tools.ietf.org/html/rfc6455#section-5.1：

您应该屏蔽客户端框架。（并且根本没有屏蔽服务器帧。）

客户端必须屏蔽它的所有帧发送到服务器（更多详细信息，请参见第5.3节）。（注意无论WebSocket协议是否正在运行，都会进行屏蔽超过TLS。）服务器必须在收到连接后关闭连接未屏蔽的帧。在这种情况下，服务器可以发送关闭状态代码为1002（协议错误）的帧，如第7.4.1节。 服务器不得屏蔽它发送给的任何帧客户端。如果客户端检测到屏蔽，则必须关闭连接帧。

这是一个有效的版本：

import os
import array
import six
import socket
import struct

OPCODE_TEXT = 0x1

try:
    # If wsaccel is available we use compiled routines to mask data.
    from wsaccel.xormask import XorMaskerSimple

    def _mask(_m, _d):
        return XorMaskerSimple(_m).process(_d)

except ImportError:
    # wsaccel is not available, we rely on python implementations.
    def _mask(_m, _d):
        for i in range(len(_d)):
            _d[i] ^= _m[i % 4]

        if six.PY3:
            return _d.tobytes()
        else:
            return _d.tostring()


def get_masked(data):
    mask_key = os.urandom(4)
    if data is None:
        data = ""

    bin_mask_key = mask_key
    if isinstance(mask_key, six.text_type):
        bin_mask_key = six.b(mask_key)

    if isinstance(data, six.text_type):
        data = six.b(data)

    _m = array.array("B", bin_mask_key)
    _d = array.array("B", data)
    s = _mask(_m, _d)

    if isinstance(mask_key, six.text_type):
        mask_key = mask_key.encode('utf-8')
    return mask_key + s


def ws_encode(data="", opcode=OPCODE_TEXT, mask=1):
    if opcode == OPCODE_TEXT and isinstance(data, six.text_type):
        data = data.encode('utf-8')

    length = len(data)
    fin, rsv1, rsv2, rsv3, opcode = 1, 0, 0, 0, opcode

    frame_header = chr(fin << 7 | rsv1 << 6 | rsv2 << 5 | rsv3 << 4 | opcode)

    if length < 0x7e:
        frame_header += chr(mask << 7 | length)
        frame_header = six.b(frame_header)
    elif length < 1 << 16:
        frame_header += chr(mask << 7 | 0x7e)
        frame_header = six.b(frame_header)
        frame_header += struct.pack("!H", length)
    else:
        frame_header += chr(mask << 7 | 0x7f)
        frame_header = six.b(frame_header)
        frame_header += struct.pack("!Q", length)

    if not mask:
        return frame_header + data
    return frame_header + get_masked(data)


def ws_decode(data):
    """
    ws frame decode.
    :param data:
    :return:
    """
    _data = [ord(character) for character in data]
    length = _data[1] & 127
    index = 2
    if length < 126:
        index = 2
    if length == 126:
        index = 4
    elif length == 127:
        index = 10
    return array.array('B', _data[index:]).tostring()


# connect
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((socket.gethostbyname('echo.websocket.org'), 80))

# handshake
handshake = 'GET / HTTP/1.1\r\nHost: echo.websocket.org\r\nUpgrade: websocket\r\nConnection: ' \
            'Upgrade\r\nSec-WebSocket-Key: gfhjgfhjfj\r\nOrigin: http://example.com\r\nSec-WebSocket-Protocol: ' \
            'echo\r\n' \
            'Sec-WebSocket-Version: 13\r\n\r\n'

sock.send(handshake)
print(sock.recv(1024))

sock.sendall(ws_encode(data='Hello, China!', opcode=OPCODE_TEXT))

# receive it back
response = ws_decode(sock.recv(1024))
print('--%s--' % response)

sock.close()

通过Python socket / WebSocket Client发送/接收WebSocket消息

1 个答案: