HTTP工作原理及HTTP请求、响应报文解读

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一、HTTP原理

1.HTTP工作原理（实例分析）：

<1> http客户端与http服务器建立TCP连接；

<2> http客户端通过浏览器向http服务器80端口发送HTTP连接请求；

<3>如果http服务器允许访问，则返回连接确认，双方建立HTTP连接；

<4>. http客户端发送HTTP页面请求（Http Analyzer V5分析结果）

<5>. http服务器寻找该HTTP文件，如果找到则返回该文件的超文本。http客户端的浏览器对接收到的超文本进行解析，翻译成格式化的页面，显示给用户；

（Http服务器模拟返回）

<6>. http服务器发送完HTTP内容后，断开HTTP连接；

<7>. 双方断开TCP连接；

/*------------------------------------------------------------HTTPServer---------------------------------------------------------------------*/#include <winsock2.h>#include <stdio.h>int main(void) {//----------------------// Initialize ......    int len = 0;    char buff[4096];    char msgret[4096];    memset( msgret, 0x00, sizeof(msgret) );//----------------------// Initialize Winsock.WSADATA wsaData;int iResult = WSAStartup(MAKEWORD(2,2), &wsaData);if (iResult != NO_ERROR) {printf("Error at WSAStartup()\n");return 1;}//----------------------// Create a SOCKET for listening for// incoming connection requests.SOCKET ListenSocket;ListenSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);if (ListenSocket == INVALID_SOCKET) {printf("Error at socket(): %ld\n", WSAGetLastError());WSACleanup();return 1;}//----------------------// The sockaddr_in structure specifies the address family,// IP address, and port for the socket that is being bound.sockaddr_in service;service.sin_family = AF_INET;service.sin_addr.s_addr = inet_addr("10.166.178.225");service.sin_port = htons(80);if (bind( ListenSocket, (SOCKADDR*) &service, sizeof(service)) == SOCKET_ERROR) {printf("bind() failed.\n");closesocket(ListenSocket);WSACleanup();return 1;}//----------------------// Listen for incoming connection requests.// on the created socketif (listen( ListenSocket, 1 ) == SOCKET_ERROR) {printf("Error listening on socket.\n");closesocket(ListenSocket);WSACleanup();return 1;}//----------------------// Accept the connection.SOCKET AcceptSocket;printf("Waiting for client to connect...\n");while(1)    {AcceptSocket = accept( ListenSocket, NULL, NULL );if (AcceptSocket == INVALID_SOCKET){printf("accept failed: %d\n", WSAGetLastError());closesocket(ListenSocket);WSACleanup();return 1;} else {printf("Client connected.\n");memset( buff, 0x00, sizeof(buff) );            len = recv(AcceptSocket, buff, 4096, 0);            printf( "msg recv:\n%s\n", buff );            sprintf( msgret, "HTTP/1.1 200 OK\n""Date: Fri, 02 Mar 2012 01:59:03 GMT\n""Server: Apache""Location: http://www.sina.com.cn/\n""Cache-Control: max-age=60\n""Expires: Fri, 02 Mar 2012 02:00:03 GMT\n""Vary: Accept-Encoding\n""Content-Length: 231\n""Content-Type: text/html; charset=iso-8859-1\n""X-Cache: MISS from xd33-82.HP08040021.sina.com.cn\n""Connection: close\n\n""<!DOCTYPE HTML PUBLIC \"-//IETF//DTD HTML 2.0//EN\">\n""<html><head>\n""<title>title test</title>\n""</head><body>\n""<h1>test body</h1>\n""<h2>test sub body</h2>\n""<p>My First Test!</p>\n""</body></html>" );len = send( AcceptSocket, msgret, sizeof(msgret), 0 );if( len <= 0 ){printf( "send failed\n" );}}//end else    }//end while// No longer need server socketclosesocket(ListenSocket);WSACleanup();return 0;}

服务器端的显示结果…

2.HTTP请求(request)&响应(response)报文解读（Http Analyzer V5分析结果）

2.1 HTTP请求报文(Header部分)

GET请求：是以实体的方式得到由请求URL所指定资源的信息，如果请求URL只是一个数据产生过程，那么最终要在响应实体中的是处理过程的结果所指向的资源，而不是处理过程的描述。GET是向服务器发索取数据的一种请求。

[1]GET /HTTP/1.1

[2]Accept:image/gif, Image/x-xbitmap, image/jpeg, Image/pjpeg, application/x-shockwave

-flash, application/x-silverlight,application/vnd.ms-excel, application/vnd.ms-powerpoint,application/msword, */* //客户端可识别的内容类型列表。

[3]Accept-Language:zh-cn 客户端所能解释的语言：简体中文

[4]UA-CPU: x86(上面未体现出来)

[5]Accept-Encoding:gzip, deflate //客户端可以解释的类型

[6]User-Agent:Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; InfoPath.3; .NET CLR2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022; .NET 4.0C; .NET4.0E)

//客户端浏览器型号(同下)