C/C++知识点之C++实现websocket协议通讯-职坐标

C/C++知识点之C++实现websocket协议通讯

小标 2018-12-03 来源：阅读 1629 评论 0

摘要：本文主要向大家介绍了 C/C++知识点之C++实现websocket协议通讯，通过具体的内容向大家展示，希望对大家学习C/C++知识点有所帮助。

本文主要向大家介绍了 C/C++知识点之C++实现websocket协议通讯，通过具体的内容向大家展示，希望对大家学习C/C++知识点有所帮助。

　　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
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
  3 #include
  4 #include
  5 #include
  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 != "\r")
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\r\n";
74     response += "Connection: upgrade\r\n";
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(message_digest), 20);
89     response += serverKey;
90     response += "\r\n";
91     response += "Upgrade: websocket\r\n\r\n";
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(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(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(0x80 | frameType);
198
199     // 填充数据长度
200     if (messageLength <= 0x7d)
201     {
202         frameHeader[1] = static_cast(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] = ‘\0‘;
217     outFrame = frame;
218
219     delete[] frame;
220     delete[] frameHeader;
221     return ret;
222 }