websocket 工作原理

自己写一个websocket(教学用)

 import socket, base64, hashlib

 sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
 sock.bind(('127.0.0.1', 9527))
 sock.listen(5)
 # 获取客户端socket对象
 conn, address = sock.accept()
 # 获取客户端的【握手】信息
 data = conn.recv(1024)
 print(data)
 """
 b'GET /ws HTTP/1.1\r\n
 Host: 127.0.0.1:9527\r\n
 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:62.0) Gecko/20100101 Firefox/62.0\r\n
 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\r\n
 Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2\r\n
 Accept-Encoding: gzip, deflate\r\n
 Sec-WebSocket-Version: 13\r\n
 Origin: http://localhost:63342\r\n
 Sec-WebSocket-Extensions: permessage-deflate\r\n
 Sec-WebSocket-Key: jocLOLLq1BQWp0aZgEWL5A==\r\n
 Cookie: session=6f2bab18-2dc4-426a-8f06-de22909b967b\r\n
 Connection: keep-alive, Upgrade\r\n
 Pragma: no-cache\r\n
 Cache-Control: no-cache\r\n
 Upgrade: websocket\r\n\r\n'
 """

 # magic string为：258EAFA5-E914-47DA-95CA-C5AB0DC85B11
 magic_string = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11'

 def get_headers(data):
     header_dict = {}
     header_str = data.decode("utf8")
     for i in header_str.split("\r\n"):
         if str(i).startswith("Sec-WebSocket-Key"):
             header_dict["Sec-WebSocket-Key"] = i.split(":")[1].strip()

     return header_dict

 def get_header(data):
     """
      将请求头格式化成字典
      :param data:
      :return:
      """
     header_dict = {}
     data = str(data, encoding='utf-8')

     header, body = data.split('\r\n\r\n', 1)
     header_list = header.split('\r\n')
     for i in range(0, len(header_list)):
         if i == 0:
             if len(header_list[i].split(' ')) == 3:
                 header_dict['method'], header_dict['url'], header_dict['protocol'] = header_list[i].split(' ')
         else:
             k, v = header_list[i].split(':', 1)
             header_dict[k] = v.strip()
     return header_dict

 headers = get_headers(data)  # 提取请求头信息
 # 对请求头中的sec-websocket-key进行加密
 response_tpl = "HTTP/1.1 101 Switching Protocols\r\n" \
                "Upgrade:websocket\r\n" \
                "Connection: Upgrade\r\n" \
                "Sec-WebSocket-Accept: %s\r\n" \
                "WebSocket-Location: ws://127.0.0.1:9527\r\n\r\n"

 value = headers['Sec-WebSocket-Key'] + magic_string
 print(value)
 ac = base64.b64encode(hashlib.sha1(value.encode('utf-8')).digest())
 response_str = response_tpl % (ac.decode('utf-8'))
 # 响应【握手】信息
 conn.send(response_str.encode("utf8"))

 while True:
     msg = conn.recv(8096)
     print(msg)

唉呀妈呀脑瓜疼

解密:

 # b'\x81\x83\xceH\xb6\x85\xffz\x85'

 hashstr = b'\x81\x83\xceH\xb6\x85\xffz\x85'
 # b'\x81    \x83    \xceH\xb6\x85\xffz\x85'

 # 将第二个字节也就是 \x83 第9-16位 进行与127进行位运算
 payload = hashstr[1] & 127
 print(payload)
 if payload == 127:
     extend_payload_len = hashstr[2:10]
     mask = hashstr[10:14]
     decoded = hashstr[14:]
 # 当位运算结果等于127时,则第3-10个字节为数据长度
 # 第11-14字节为mask 解密所需字符串
 # 则数据为第15字节至结尾

 if payload == 126:
     extend_payload_len = hashstr[2:4]
     mask = hashstr[4:8]
     decoded = hashstr[8:]
 # 当位运算结果等于126时,则第3-4个字节为数据长度
 # 第5-8字节为mask 解密所需字符串
 # 则数据为第9字节至结尾

 if payload <= 125:
     extend_payload_len = None
     mask = hashstr[2:6]
     decoded = hashstr[6:]

 # 当位运算结果小于等于125时,则这个数字就是数据的长度
 # 第3-6字节为mask 解密所需字符串
 # 则数据为第7字节至结尾

 str_byte = bytearray()

 for i in range(len(decoded)):
     byte = decoded[i] ^ mask[i % 4]
     str_byte.append(byte)

 print(str_byte.decode("utf8"))

脑瓜疼脑瓜疼

加密:

 import struct
 msg_bytes = "hello".encode("utf8")
 token = b"\x81"
 length = len(msg_bytes)

 if length < 126:
     token += struct.pack("B", length)
 elif length == 126:
     token += struct.pack("!BH", 126, length)
 else:
     token += struct.pack("!BQ", 127, length)

 msg = token + msg_bytes

 print(msg)

加密算法脑瓜疼