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Web programming (II) CGI related

2022-07-25 12:07:00 【Boring ah le】

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1、CGI environment variable

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stay /usr/local/apache/cgi-bin/ Under the new CGI Script env.cpp:

#include <iostream>
#include <stdlib.h>
using namespace std;

const string ENV[24] = 
{
    
	"COMSPEC", "DOCUMENT_ROOT", "GATEWAY_INTERFACE", 
	"HTTP_ACCEPT", "HTTP_ACCEPT_ENCODING",
	"HTTP_ACCEPT_LANGUAGE", "HTTP_CONNECTION", 
	"HTTP_HOST", "HTTP_USER_AGENT", "PATH", 
	"QUERY_STRING", "REMOTE_ADDR", "REMOTE_PORT",
	"REQUEST_METHOD", "REQUEST_URI", "SCRIPT_FILENAME",
	"SCRIPT_NAME", "SERVER_ADDR", "SERVER_ADMIN",
	"SERVER_NAME","SERVER_PORT","SERVER_PROTOCOL",
	"SERVER_SIGNATURE","SERVER_SOFTWARE"};  

int main()
{
    
	cout<<"Content-type:text/html\r\n\r\n";
	cout<<"<html>\n";
	cout<<"<head>\n";
	cout<<"<title>CGI Envrionment Variables</title>\n";
	cout<<"</head>\n";
	cout<<"<body>\n";
	cout<<"<table border=\"0\"cellspacing=\"2\">";

	for(int i=0;i<24;i++)
	{
    
		cout<<"<tr><td>"<<ENV[i]<<"</td><td>";
		char *value = getenv(ENV[i].c_str()); 
		if(value!= 0)
		{
    
		    cout << value;
		}
		else
		{
    
		    cout<<"Environment variable does not exist.";
		}
		cout<<"</td></tr>\n";
	}

	cout<<"</table><\n";
	cout<<"</body>\n";
	cout<<"</html>\n"; 
    return 0;
}

g++ -o env env.cpp

Local execution cannot get environment variables , Only put it in cgi-bin Next , It can only be executed in the browser .

Turn on http service , Enter the following in the browser

http://192.168.122.1/cgi-bin/env

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2、GET How to get parameters

stay GET Methods ,CGI The program cannot get data directly from the standard input of the server , Because the server puts it
Received from standard input Data is encoded into environment variables QUERY_STRING （ or PATH_INFO ）. use GET When the method is used , Just append these data to URL At the end of , Such as
http://192.168.122.1/cgi-bin/get?a=l&b=2&c=3 ,
Now QUERY_STRING The value of is a=l&b=2&c=3

Write test script

#include<iostream>
#include<stdlib.h>
#include<vector>
#include<string>
using namespace std;

/* Functions that separate strings  sData  It's the source string , sDelim  The separator is ,  The return value is a separated list of strings */
vector<string> StringSplit(const string& sData, const string& sDelim)
{
    
	vector<string>vItems;
	vItems.clear();
	string::size_type bpos = 0;
	string::size_type epos = 0;
	string::size_type nlen = sDelim.size();
	while ((epos=sData.find(sDelim, epos)) != string::npos)
	{
    
		vItems.push_back(sData.substr(bpos, epos-bpos));
		epos += nlen;
		bpos = epos;
    }
	vItems.push_back(sData.substr(bpos, sData.size()-bpos));
	return vItems;
}

int main()
{
    

	cout << "Content-type:text/html\r\n\r\n";
	cout << "<html>\n";
	cout << "<head>\n";
	cout << "<title>Hello World - First CGI Program</title>\n";
	cout << "</head>\n";
	cout << "<body>\n";	
	cout<<"get parameter:<br/>";
	
	char *value = getenv("QUERY_STRING");
	if(value!= 0)
	{
    
	    /*"a=1&b=2&c=3"*/

	    /* So here is getting  GET  The code of the parameter , First, according to “＆” To separate , And then based on “＝” Symbol for secondary separation ,  You can get the content of the parameter  */
	   vector<string>paras=StringSplit((const string)value,"&");
	   vector<string>::iterator iter=paras.begin();
	   for(;iter!=paras.end();iter++)
	   {
    

           vector<string>singlepara=StringSplit(*iter,"=");
	       cout<<singlepara[0]<<" "<<singlepara[1]<<"<br/>";
	   }
	   cout << "</body>\n";
	   cout << "</html>\n";   
	   return 0;
	}
}

After compiling, put apache/cgi-bin/ Under the table of contents

Type in the browser ：

http://192.168.122.1/cgi-bin/get?a=1&b=2&c=3&d=4

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3、POST How to get parameters

stay POST Methods , CGI The program can get data directly from the standard input of the server , But first from
CONTENT_LENGTH From this environment variable POST Length of parameter , Then read the content of the corresponding length .

Write test script post.html

<html>
<head>
<title>CGI Post</title>
</head>
<body>
<tr><td>
<div style="font-weight:bold; font-size:15px">Method: POST</div>
<div>lease input two number:<div>
<form method="post" action="./cgi-bin/post">
<input type="txt" size="3" name="m">*
<input type="txt" size="3" name="n">=
<input type="submit" value="result">
</form>
</td></tr>
</table>
</body>
</html>

Write a test program post.cpp

#include<iostream>
#include<stdlib.h>
#include<stdio.h>
using namespace std;

int main()
{
    
	cout << "Content-type:text/html\r\n\r\n";
	cout << "<html>\n";
	cout << "<head>\n";
	cout << "<title>Testing Post</title>\n";
	cout << "</head>\n";
	cout << "<body>\n";	

	char *lenstr =getenv("CONTENT_LENGTH");
	if(lenstr==NULL)
	{
    

		cout<<"Error, CONTENT_LENGTH should be entered!"<<"<br/>";
	}
	else
	{
    
		int len=atoi(lenstr);
		char poststr[20];
		fgets(poststr,len+1,stdin);
		cout<<"poststr:"<<poststr<<"<br/>";	
		char m[10],n[10];
		//m=3&n=4
		if(sscanf(poststr,"m=%[^&]&n=%s",m,n)!=2)//????
		{
    
			cout<<"Error: Parameters are not right!<br/>";
		}
		else
		{
    
			cout<<"m * n = "<<atoi(m)*atoi(n)<<"<br/>";
		}
	}
	cout << "</body>\n";
	cout << "</html>\n";   
	return 0;
}

g++ -o post post.cpp

Copy post To /usr/local/apache/cgi-bin/ Next
Copy post.html To /usr/local/apache/htdocs/ Next

Browser input ：

http://192.168.122.1/post.html

input data , Click on result

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4、 Get access to the user's IP

Sometimes when positioning problems , Need to know the user's IP Address , Get users IP Address has two environment variables ：
HTTP_VIA and REMOTE_ADDR. When users use proxy server to access , HTTP_QVIA The value of the environment variable is not empty , User IP That is, the proxy server's IP 了 . When the user does not use a proxy server to access , be IP The address is in REMOTE_ADDR In the environment variable

#include<iostream>
#include<stdlib.h>
#include<cstring>
#include<stdio.h>
using namespace std;

// Get users IP
std::string GetClientIP() 
{
    
	const char * p = getenv("REMOTE_ADDR");

	if(p) 
	{
    
		return p;
	}	
	
	return "0.0.0.0";
}



int main()
{
    
	cout << "Content-type:text/html\r\n\r\n";
	cout << "<html>\n";
	cout << "<head>\n";
	cout << "<title>Testing Post</title>\n";
	cout << "</head>\n";
	cout << "<body>\n";	

	char *lenstr =getenv("CONTENT_LENGTH");
	if(lenstr==NULL)
	{
    

		cout<<"Error, CONTENT_LENGTH should be entered!"<<"<br/>";
	}
	else
	{
    
		int len=atoi(lenstr);
		char poststr[20];
		fgets(poststr,len+1,stdin);
		cout<<"poststr:"<<poststr<<"<br/>";	
		char m[10],n[10];
		//m=3&n=4
		if(sscanf(poststr,"m=%[^&]&n=%s",m,n)!=2)//????
		{
    
			cout<<"Error: Parameters are not right!<br/>";
		}
		else
		{
    
			cout<<"m * n = "<<atoi(m)*atoi(n)<<"<br/>";
		}
	}

	cout<<"usr ip="<< GetClientIP() <<"<br/>";


	cout << "</body>\n";
	cout << "</html>\n";   
	return 0;
}