C++实现websocket协议通讯

　　在获取服务器的数据时，我们传统的做法是通过前端进行请求服务器返回数据。这样如果我们要获取的数据不是连续的，或者服务器想想前端推送数据只能通过ajax等轮询请求了。html5以后我们可以通过websocket和服务器进行通信，前端和服务连接后就可以进行双工连接了。服务器有数据就能实时的给前端推送,而不需要我定时的去请求。

　　websocket简单来说就是先前端向服务器发送http的请求，服务端通过前端请求的http的key值进过sha1和base64加密返回给前端,这一过程称为“握手”，如果验证成功就能进行websocket通讯了。握手成功后前端和后端通讯都要符合webscoket的协议才能通讯。关于websocket的协议大家可以网上查找，这里不作讨论。

　　最近在要实现一个后端将设配读到数据主动发前端的功能，网上查找了一些大佬写好程序进行参考更改。这里谢谢他们，希望没有侵权。下面是主要代码。

 1 #ifndef __WebSocketProtocol_H__
 2 #define __WebSocketProtocol_H__
 3 
 4 #include <string>
 5 
 6 using std::string;
 7 
 8 class CWebSocketProtocol
 9 {
10 public:
11     enum WS_Status
12     {
13         WS_STATUS_CONNECT = 0,
14         WS_STATUS_UNCONNECT = 1,
15     };
16 
17     enum WS_FrameType
18     {
19         WS_EMPTY_FRAME = 0xF0,
20         WS_ERROR_FRAME = 0xF1,
21         WS_TEXT_FRAME = 0x01,
22         WS_BINARY_FRAME = 0x02,
23         WS_PING_FRAME = 0x09,
24         WS_PONG_FRAME = 0x0A,
25         WS_OPENING_FRAME = 0xF3,
26         WS_CLOSING_FRAME = 0x08
27     };
28 
29     static CWebSocketProtocol * getInstance();
30 
31     int getResponseHttp(string &request, string &response);
32     int wsDecodeFrame(string inFrame, string &outMessage);    //解码帧
33     int wsEncodeFrame(string inMessage, string &outFrame, enum WS_FrameType frameType);    //编码帧打包
34 
35 private:
36     CWebSocketProtocol();
37     ~CWebSocketProtocol();
38 
39     class CGrabo
40     {
41     public:
42         ~CGrabo()
43         {
44             if (m_inst != 0)
45             {
46                 delete m_inst;
47                 m_inst = 0;
48             }
49         }
50     };
51 
52     static CGrabo m_grabo;
53     static    CWebSocketProtocol * m_inst;
54 };
55 
56 #endif

  1 #include "WebSocketProtocol.h"
  2 #include <iostream>
  3 #include <sstream>
  4 #include <string.h>
  5 #include <arpa/inet.h>
  6 #include "sha1.h"
  7 #include "base64.h"
  8 
  9 const char * MAGIC_KEY = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
 10 
 11 CWebSocketProtocol::CGrabo CWebSocketProtocol::m_grabo;
 12 CWebSocketProtocol * CWebSocketProtocol::m_inst = 0;
 13 
 14 CWebSocketProtocol::CWebSocketProtocol()
 15 {
 16 }
 17 
 18 
 19 CWebSocketProtocol::~CWebSocketProtocol()
 20 {
 21 }
 22 
 23 
 24 
 25 CWebSocketProtocol * CWebSocketProtocol::getInstance()
 26 {
 27     if (m_inst == 0)
 28     {
 29         m_inst = new CWebSocketProtocol;
 30     }
 31 
 32     return m_inst;
 33 }
 34 
 35 int CWebSocketProtocol::getResponseHttp(string &request, string &response)
 36 {
 37     // 解析http请求头信息  
 38     int ret = WS_STATUS_UNCONNECT;
 39     std::istringstream stream(request.c_str());
 40     std::string reqType;
 41     std::getline(stream, reqType);
 42     if (reqType.substr(0, 4) != "GET ")
 43     {
 44         return ret;
 45     }
 46 
 47     std::string header;
 48     std::string::size_type pos = 0;
 49     std::string websocketKey;
 50     while (std::getline(stream, header) && header != "
")
 51     {
 52         header.erase(header.end() - 1);
 53         pos = header.find(": ", 0);
 54         if (pos != std::string::npos)
 55         {
 56             std::string key = header.substr(0, pos);
 57             std::string value = header.substr(pos + 2);
 58             if (key == "Sec-WebSocket-Key")
 59             {
 60                 ret = WS_STATUS_CONNECT;
 61                 websocketKey = value;
 62                 break;
 63             }
 64         }
 65     }
 66 
 67     if (ret != WS_STATUS_CONNECT)
 68     {
 69         return ret;
 70     }
 71 
 72     // 填充http响应头信息  
 73     response = "HTTP/1.1 101 Switching Protocols
";
 74     response += "Connection: upgrade
";
 75     response += "Sec-WebSocket-Accept: ";
 76 
 77     std::string serverKey = websocketKey + MAGIC_KEY;
 78 
 79     SHA1 sha;
 80     unsigned int message_digest[5];
 81     sha.Reset();
 82     sha << serverKey.c_str();
 83 
 84     sha.Result(message_digest);
 85     for (int i = 0; i < 5; i++) {
 86         message_digest[i] = htonl(message_digest[i]);
 87     }
 88     serverKey = base64_encode(reinterpret_cast<const unsigned char*>(message_digest), 20);
 89     response += serverKey;
 90     response += "
";
 91     response += "Upgrade: websocket

";
 92 
 93     return ret;
 94 }
 95 
 96 int CWebSocketProtocol::wsDecodeFrame(string inFrame, string &outMessage)
 97 {
 98     int ret = WS_OPENING_FRAME;
 99     const char *frameData = inFrame.c_str();
100     const int frameLength = inFrame.size();
101     if (frameLength < 2)
102     {
103         ret = WS_ERROR_FRAME;
104     }
105 
106     // 检查扩展位并忽略  
107     if ((frameData[0] & 0x70) != 0x0)
108     {
109         ret = WS_ERROR_FRAME;
110     }
111 
112     // fin位: 为1表示已接收完整报文, 为0表示继续监听后续报文  
113     ret = (frameData[0] & 0x80);
114     if ((frameData[0] & 0x80) != 0x80)
115     {
116         ret = WS_ERROR_FRAME;
117     }
118 
119     // mask位, 为1表示数据被加密  
120     if ((frameData[1] & 0x80) != 0x80)
121     {
122         ret = WS_ERROR_FRAME;
123     }
124 
125     // 操作码  
126     uint16_t payloadLength = 0;
127     uint8_t payloadFieldExtraBytes = 0;
128     uint8_t opcode = static_cast<uint8_t>(frameData[0] & 0x0f);
129     if (opcode == WS_TEXT_FRAME)
130     {
131         // 处理utf-8编码的文本帧  
132         payloadLength = static_cast<uint16_t>(frameData[1] & 0x7f);
133         if (payloadLength == 0x7e)
134         {
135             uint16_t payloadLength16b = 0;
136             payloadFieldExtraBytes = 2;
137             memcpy(&payloadLength16b, &frameData[2], payloadFieldExtraBytes);
138             payloadLength = ntohs(payloadLength16b);
139         }
140         else if (payloadLength == 0x7f)
141         {
142             // 数据过长,暂不支持  
143             ret = WS_ERROR_FRAME;
144         }
145     }
146     else if (opcode == WS_BINARY_FRAME || opcode == WS_PING_FRAME || opcode == WS_PONG_FRAME)
147     {
148         // 二进制/ping/pong帧暂不处理  
149     }
150     else if (opcode == WS_CLOSING_FRAME)
151     {
152         ret = WS_CLOSING_FRAME;
153     }
154     else
155     {
156         ret = WS_ERROR_FRAME;
157     }
158 
159     // 数据解码  
160     if ((ret != WS_ERROR_FRAME) && (payloadLength > 0))
161     {
162         // header: 2字节, masking key: 4字节  
163         const char *maskingKey = &frameData[2 + payloadFieldExtraBytes];
164         char *payloadData = new char[payloadLength + 1];
165         memset(payloadData, 0, payloadLength + 1);
166         memcpy(payloadData, &frameData[2 + payloadFieldExtraBytes + 4], payloadLength);
167         for (int i = 0; i < payloadLength; i++)
168         {
169             payloadData[i] = payloadData[i] ^ maskingKey[i % 4];
170         }
171 
172         outMessage = payloadData;
173         delete[] payloadData;
174     }
175 
176     return ret;
177 }
178 
179 int CWebSocketProtocol::wsEncodeFrame(string inMessage, string &outFrame, enum WS_FrameType frameType)
180 {
181     int ret = WS_EMPTY_FRAME;
182     const uint32_t messageLength = inMessage.size();
183     if (messageLength > 32767)
184     {
185         // 暂不支持这么长的数据
186         std::cout << "暂不支持这么长的数据" << std::endl;
187 
188         return WS_ERROR_FRAME;
189     }
190 
191     uint8_t payloadFieldExtraBytes = (messageLength <= 0x7d) ? 0 : 2;
192     // header: 2字节, mask位设置为0(不加密), 则后面的masking key无须填写, 省略4字节  
193     uint8_t frameHeaderSize = 2 + payloadFieldExtraBytes;
194     uint8_t *frameHeader = new uint8_t[frameHeaderSize];
195     memset(frameHeader, 0, frameHeaderSize);
196     // fin位为1, 扩展位为0, 操作位为frameType  
197     frameHeader[0] = static_cast<uint8_t>(0x80 | frameType);
198 
199     // 填充数据长度  
200     if (messageLength <= 0x7d)
201     {
202         frameHeader[1] = static_cast<uint8_t>(messageLength);
203     }
204     else
205     {
206         frameHeader[1] = 0x7e;
207         uint16_t len = htons(messageLength);
208         memcpy(&frameHeader[2], &len, payloadFieldExtraBytes);
209     }
210 
211     // 填充数据  
212     uint32_t frameSize = frameHeaderSize + messageLength;
213     char *frame = new char[frameSize + 1];
214     memcpy(frame, frameHeader, frameHeaderSize);
215     memcpy(frame + frameHeaderSize, inMessage.c_str(), messageLength);
216     frame[frameSize] = '';
217     outFrame = frame;
218 
219     delete[] frame;
220     delete[] frameHeader;
221     return ret;
222 }

参考资料:http://www.cnblogs.com/jice1990/p/5435419.html

　　　　http://blog.csdn.net/grafx/article/details/54234518#

项目下载

相关阅读:
P6007 [USACO20JAN]Springboards G
CF1000F One Occurrence
P6100 [USACO19FEB]Painting the Barn G
P5838 [USACO19DEC]Milk Visits G
P4085 [USACO17DEC]Haybale Feast
P4267 [USACO18FEB]Taming the Herd
P1712 [NOI2016]区间
 CF786B Legacy
P5665 划分
 NOI2020网上同步赛游记
原文地址：https://www.cnblogs.com/fyluyg/p/6534574.html