?WebSocket協議是基于TCP的一種新的協議。它實現了瀏覽器與服務器全雙工(full-duplex)通信。其本質是保持TCP連接，在瀏覽器和服務端通過Socket進行通信。

1、啟動客戶端

<script type="text/javascript">var socket = new WebSocket("ws://127.0.0.1:8002/xxoo");... </script>

2、啟動服務端并建立連接

import socketsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) sock.bind(('127.0.0.1', 8002)) sock.listen(5) # 獲取客戶端socket對象 conn, address = sock.accept() # 獲取客戶端的【握手】信息 data = conn.recv(1024) ... ... ... conn.send('響應【握手】信息')

　　請求和響應的握手過程：

　　　　- 從請求握手的信息中提取Sec-WebSocket-Key

　　　　- 利用sha1和base64對magic_string（258EAFA5-E914-47DA-95CA-C5AB0DC85B11）和Sec-WebSocket-Key進行加密

　　　　- 將加密結果響應給客戶端

　　代碼如下：

import socket import base64 import hashlibdef get_headers(data):"""將請求頭格式化成字典:param data::return:"""header_dict = {}data = str(data, encoding='utf-8')for i in data.split('\r\n'):print(i)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_dictsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) sock.bind(('127.0.0.1', 8002)) sock.listen(5)conn, address = sock.accept() data = conn.recv(1024) headers = get_headers(data) # 提取請求頭信息 # 對請求頭中的sec-websocket-key進行加密 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://%s%s\r\n\r\n" magic_string = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11' value = headers['Sec-WebSocket-Key'] + magic_string ac = base64.b64encode(hashlib.sha1(value.encode('utf-8')).digest()) response_str = response_tpl % (ac.decode('utf-8'), headers['Host'], headers['url']) # 響應【握手】信息 conn.send(bytes(response_str, encoding='utf-8')) View Code

3、客戶端和服務端收發數據

　　客戶端和服務端傳輸數據時，需要對數據進行【封包】和【解包】。客戶端的JavaScript類庫封裝了【封包】和【解包】過程，但Socket服務端需要手動實現：

　　第一步：獲取客戶端發送的數據【解包】

　　　　【解包】的詳細過程:

The MASK bit simply tells whether the message is encoded. Messages from the client must be masked, so your server should expect this to be 1. (In fact, section 5.1 of the spec says that your server must disconnect from a client if that client sends an unmasked message.) When sending a frame back to the client, do not mask it and do not set the mask bit. We'll explain masking later. Note: You have to mask messages even when using a secure socket.RSV1-3 can be ignored, they are for extensions. The opcode field defines how to interpret the payload data: 0x0 for continuation, 0x1 for text (which is always encoded in UTF-8), 0x2 for binary, and other so-called "control codes" that will be discussed later. In this version of WebSockets, 0x3 to 0x7 and 0xB to 0xF have no meaning.The FIN bit tells whether this is the last message in a series. If it's 0, then the server will keep listening for more parts of the message; otherwise, the server should consider the message delivered. More on this later. Decoding Payload LengthTo read the payload data, you must know when to stop reading. That's why the payload length is important to know. Unfortunately, this is somewhat complicated. To read it, follow these steps: Read bits 9-15 (inclusive) and interpret that as an unsigned integer. If it's 125 or less, then that's the length; you're done. If it's 126, go to step 2. If it's 127, go to step 3. Read the next 16 bits and interpret those as an unsigned integer. You're done. Read the next 64 bits and interpret those as an unsigned integer (The most significant bit MUST be 0). You're done. Reading and Unmasking the DataIf the MASK bit was set (and it should be, for client-to-server messages), read the next 4 octets (32 bits); this is the masking key. Once the payload length and masking key is decoded, you can go ahead and read that number of bytes from the socket. Let's call the data ENCODED, and the key MASK. To get DECODED, loop through the octets (bytes a.k.a. characters for text data) of ENCODED and XOR the octet with the (i modulo 4)th octet of MASK. In pseudo-code (that happens to be valid JavaScript): var DECODED = ""; for (var i = 0; i < ENCODED.length; i++) {DECODED[i] = ENCODED[i] ^ MASK[i % 4]; }Now you can figure out what DECODED means depending on your application. 0 1 2 30 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 +-+-+-+-+-------+-+-------------+-------------------------------+ |F|R|R|R| opcode|M| Payload len | Extended payload length | |I|S|S|S| (4) |A| (7) | (16/64) | |N|V|V|V| |S| | (if payload len==126/127) | | |1|2|3| |K| | | +-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - + | Extended payload length continued, if payload len == 127 | + - - - - - - - - - - - - - - - +-------------------------------+ | |Masking-key, if MASK set to 1 | +-------------------------------+-------------------------------+ | Masking-key (continued) | Payload Data | +-------------------------------- - - - - - - - - - - - - - - - +

　　　　代碼如下：

info = conn.recv(8096)# 用數據包的第二個字節，與127作與位運算，拿到前七位 payload_len = info[1] & 127 # 這七位在數據頭部分成為payload，如果payload等于126，就要再擴展2個字節 if payload_len == 126:extend_payload_len = info[2:4]mask = info[4:8]decoded = info[8:] # 如果等于127，就要再擴展8個字節 elif payload_len == 127:extend_payload_len = info[2:10]mask = info[10:14]decoded = info[14:] # 如果小于等于125，那它就占這一個字節 else:extend_payload_len = Nonemask = info[2:6]decoded = info[6:]# 當payload確定之后，再往后數4個字節，這4個字節成為masking key，再之后的內容就是接收到的數據部分了 # 數據部分的每一字節都要和masking key作異或位運算，得出來的結果就是真實的數據內容 bytes_list = bytearray() for i in range(len(decoded)):chunk = decoded[i] ^ mask[i % 4]bytes_list.append(chunk) body = str(bytes_list, encoding='utf-8') print(body)

　　第二步：向客戶端發送數據【封包】

def send_msg(conn, msg_bytes):"""WebSocket服務端向客戶端發送消息:param conn: 客戶端連接到服務器端的socket對象,即： conn,address = socket.accept():param msg_bytes: 向客戶端發送的字節:return: """import structtoken = b"\x81"length = len(msg_bytes)if length < 126:token += struct.pack("B", length)elif length <= 0xFFFF:token += struct.pack("!BH", 126, length)else:token += struct.pack("!BQ", 127, length)msg = token + msg_bytesconn.send(msg)return True

　　第三步：客戶端代碼

<!DOCTYPE html> <html> <head lang="en"><meta charset="UTF-8"><title></title> </head> <body><div><input type="text" id="txt"/><input type="button" id="btn" value="提交" onclick="sendMsg();"/><input type="button" id="close" value="關閉連接" onclick="closeConn();"/></div><div id="content"></div><script type="text/javascript">var socket = new WebSocket("ws://127.0.0.1:8003/chatsocket");socket.onopen = function () {/* 與服務器端連接成功后，自動執行 */var newTag = document.createElement('div');newTag.innerHTML = "【連接成功】";document.getElementById('content').appendChild(newTag);};socket.onmessage = function (event) {/* 服務器端向客戶端發送數據時，自動執行 */var response = event.data;var newTag = document.createElement('div');newTag.innerHTML = response;document.getElementById('content').appendChild(newTag);};socket.onclose = function (event) {/* 服務器端主動斷開連接時，自動執行 */var newTag = document.createElement('div');newTag.innerHTML = "【關閉連接】";document.getElementById('content').appendChild(newTag);};function sendMsg() {var txt = document.getElementById('txt');socket.send(txt.value);txt.value = "";}function closeConn() {socket.close();var newTag = document.createElement('div');newTag.innerHTML = "【關閉連接】";document.getElementById('content').appendChild(newTag);}</script> </body> </html>

　　以上便利用Python完成了基于websocket的通信。

　　它的原理就是利用對magic_string和Sec-WebSocket-Key進行加密來建立長連接，在收發數據時，利用payload和masking key來獲取數據部分。

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轉載于:https://www.cnblogs.com/value-code/p/8746753.html

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