popen, select, PHP client, 執行遠端程式

tags: C LANGUAGE PHP popen 執行遠端程式 select remote execution http simple web server web based linux

Author: WhoAmI
email: [e-mail]
Date: 20220729
Copyright: CC BY-NC-SA

特別注意 PHP 網路 IO 與 c 語言方法, 再使用 popen (與 system() 有何不同?)之間的差異!

Linux mkfifo Command Tutorial for Beginners (with Examples)

PHP 基本語言使用可參閱 PHP Tutorial( w3schools)

a. PHP 另外重要的是 PHP Sessions 與 PHP Cookies (請用 Wireshark 觀察 HTTP frames)
b. PHP 與 Database(MySQL, SQLite, …)除了考慮安全性以外, 也應考慮 網路連線的特性(避免每一次重新連線至Database, Why?)
c. HTTP 基本上是 stateless protocol 應用, 當 Cookies 不允許使用時您會如何處理?
d.一般 網路上提供的 virtual server 的作法是什麼? Why?

Source code: selectexe.c, run.php

a. 為什麼 需要用 int writet(int fd,char *buf,int len,int secs)?

b. execl, execlp, execle, execv, execvp, execvpe , popen, system() 有何差別?

( Linux 如有需要, 最好使用 popen() 而不要用 system())

請自行架設環境 練習

注意 有BUG, FIXIT

selectexe.c
注意 FIXIT

/*

Important syytem call:
  select()

I/O re-direction
popen application

WhoAmI([e-mail]) 20191210
*/



#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>

#include <sys/wait.h>

#define PANIC(msg) { perror(msg); exit(EXIT_FAILURE); }
#define STDIN 0


static void sig_handler(int signo)
{
    pid_t pid;
    int stat;


    switch(signo)
    {

        case SIGCHLD:
            printf("SIGCHLD=%d\n",signo);
            pid=waitpid(0,&stat,WNOHANG);
            break;

        case SIGINT:
            printf("SIGINT=%d\n",signo);
            break;
        case SIGALRM:
            printf("Got SIGALRM=%d, exit!\n",signo);
            exit( EXIT_FAILURE);

            break;

        case SIGPIPE:
             printf("Got SIGPIPE=%d, exit!\n",signo);
             //exit( EXIT_FAILURE);
         
        default:
            printf("signal=%d\n",signo);

        }
   

    return;
}

#define MY_LENTH 1023

int writet(int fd,char *buf,int len,int secs)
{
 fd_set w_fds;
 struct timeval tv;
    int n;
    int m,j;

    tv.tv_sec = secs;
    tv.tv_usec = 0;
    FD_ZERO(&w_fds);
 FD_SET(fd,&w_fds);

    m=0;
    j=0;
    do{
    /* BUG!  why?*/
     n = select(fd+1, NULL, &w_fds, NULL,  &tv );

     switch(n){
            case 0:
         
                errno = ETIMEDOUT;
                printf("Write timeout!\n");       

                return -1;
                break;
            case -1:
                return -1;

            default:
                //FIXIT! why?
                 m=write(fd,buf+j,len-j);
                 j=j+m;

                 break;
      }

     }while(m>0);
}




static int run(int ofd, char *buf,int n)
{

   FILE *fp;
   int fd;
   unsigned char *p;
   int i,len;
   char obuf[MY_LENTH+1];

 
 
   for(p=buf;*p>=' ';p++){
   
   }
   *p=0;

   printf("%s\n",buf);
  // fp=popen("ls -l","r");
   fp = popen(buf,"r");
   fd=fileno(fp);

   do{


     memset(obuf,0,MY_LENTH+1);

     p=fgets(obuf, MY_LENTH , fp);

     obuf[MY_LENTH]=0;
   

     printf("%s",obuf);

     if(ofd>0){

          if(p)writet(ofd,p,strlen(p),1);
     }

   }while(p!=NULL);
   pclose(fp);
 

 
}

int main(int argc, char *argv[])
{
 int server_fd;
 int client_fd;
 struct sockaddr_in server_addr;
 struct sockaddr_in client_addr;
 fd_set master_fds;
 fd_set read_fds;
 int fdmax;
 struct timeval tv; 
 int port;
 int len;
 int i, j;
 char buf[1024],ch;
 int nbytes;
 int yes=1;
 int retval;
    char cmd[512];
    int n;
    int timeout;
 
 
 if(argc>1)port=atoi(argv[1]);
        else port=9999;

    if(argc>2)timeout=atoi(argv[2]);
        else timeout=160;

    printf("Server start port=%d timeout=%d\n",port,timeout);

       
    signal (SIGPIPE, sig_handler); 
// signal (SIGPIPE,SIG_IGN);

 FD_ZERO(&master_fds);
 FD_ZERO(&read_fds);
 
 if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == -1) PANIC("socket");
 if (setsockopt(server_fd,SOL_SOCKET,SO_REUSEADDR,&yes,sizeof(int)) == -1) PANIC("setsockopt");
  
        memset(&server_addr,0,sizeof(server_addr));
 server_addr.sin_family = AF_INET;
 server_addr.sin_addr.s_addr = INADDR_ANY;
 server_addr.sin_port = htons(port);
 
 if (bind(server_fd,(struct sockaddr *)&server_addr,sizeof(server_addr))==-1) PANIC("bind");
 if (listen(server_fd,10) == -1) PANIC("listen");

 FD_SET(server_fd,&master_fds);
 FD_SET(STDIN,&master_fds);
 
 fdmax = server_fd;
   
 //  Server Loop
 for(;;) {
  read_fds=master_fds;
  tv.tv_sec = 160;
         tv.tv_usec = 0;
  retval = select(fdmax+1,&read_fds,NULL,NULL,&tv);
  
  switch(retval){   
       case -1:
   perror("select");
   continue;
       case 0:
          printf("Time Out...");
          for(i=3; i<= fdmax; i++) {
           if (FD_ISSET(i,&master_fds)) close(i);
          }  
          exit(0);            
  }
                  
  for(i=0; i<=fdmax; i++) {
      if (FD_ISSET(i,&read_fds)) {
         if (i==server_fd) { //Handle New Connection
    len = sizeof(client_addr);
    if ((client_fd=accept(server_fd,(struct sockaddr *)&client_addr,&len)) == -1) {
                perror("accept");
                continue;
    } else {
         FD_SET(client_fd, &master_fds);
                       if (client_fd > fdmax) {
                    fdmax = client_fd;
                        }
                       printf("New connection from %s on socket %d\n",inet_ntoa(client_addr.sin_addr),client_fd);
                             n=sprintf(cmd,"Welcome new connection from IP:%s on socket %d\n",inet_ntoa(client_addr.sin_addr),client_fd);
                             write(client_fd,cmd,n);
                 }
                }else { // Handle data from the clients and the STDIN
                 
     if ((nbytes=read(i, buf, sizeof(buf))) > 0) {

                   if(buf[0]=='!'){
                   
                      run(i, &buf[1],nbytes-1);
                      //close connection

                      close(i);
                   FD_CLR(i, &master_fds);
                   
                   }if(buf[0]=='@'){
                      //Don't close connction
                      run(i, &buf[1],nbytes-1);

                   }else{
                     
                   
                   }
         write(1,buf,nbytes);//


         for(j=0; j<=fdmax; j++) {
                                   if (FD_ISSET(j, &master_fds)) {
                                       if (j!=server_fd && j!=i &&j!=0) {
                                            if (send(j, buf, nbytes, 0) == -1) {
                                                perror("send");
                                            }
                                        }
                                   }
                                   }//for
      
                          } else {
                                perror("recv");
                       close(i);
                       FD_CLR(i, &master_fds);
                          }
                   } //for loop

                 }//if
            } //for scan all IO
        }//for server loop
       return 0;
}

run.php

<!DOCTYPE html>
<html>
<body>

<h2>PHP TCP Client</h2>

<?php

$myaction=$_SERVER['PHP_SELF'];

echo $myaction;

//set the default values
     
$idnumber=0; 

//Check GET method
if($_SERVER['REQUEST_METHOD'] == 'GET'){
if(isset($idnumber)){


    if($idnumber==0){
       //set the default values
       $ip="127.0.0.1";
       $port=9999;
       $cmd="ls -al";
       $host="www.org";
       $idnumber=$idnumber+1; 
    }else{
       //get from FORM
       $ip=$_GET["IP"];
       $port=$_GET["PORT"];
       $cmd= $_GET["CMD"];

       $host=$_GET["HOST"];
       $idnumber=$_GET["idnumber"];
       $idnumber=$idnumber+1;
    }
}else{

  //set the default values
       $idnumber=0;
       $ip="127.0.0.1";
       $port=9999;
       $cmd="ls -al";
       $host="www.org";

} 
 

}

//Check POST method

if($_SERVER['REQUEST_METHOD'] == 'POST'){

   $ip=$_POST["IP"];

   $port=$_POST["PORT"];
   $cmd= $_POST["CMD"];

    $host=$_POST["HOST"];
    $idnumber=$_POST["idnumber"];
$idnumber=$idnumber+1;

}



?>

<p  style="color:green" >POST Method </p>


<form action="<?php echo $myaction; ?>" method="POST">
  IP:PORT<br>
  <input type="text" name="IP" value="<?php echo $ip; ?>">

  <input type="text" name="PORT" value="<?php echo $port; ?>">

  <br>CMD:<br>
  <input type="text" name="CMD" value="<?php echo $cmd; ?>">

  <br><br>

  <input type="hidden" name="idnumber" value="<?php echo $idnumber; ?>" >
  <input type="submit"  style="color:green" value="Submit (POST)">
</form>

<p  style="color:blue" >If you click the "Submit" button, the form-data will be sent to a page called "<?php echo $url; ?>".</p>


<?PHP


 $idnumber=0;
 $host="www.org"; //FIXIT


if($idnumber>=0){

echo "<p  style='color:blue'>idnumber=$idnumber<BR>IP= $ip: PORT=$port:CMD=$cmd:HOST:$host </p><BR>";
//$message = "GET $url HTTP/1.1\r\nHOST: $host\r\n\r\n\r\n";

$message = "!$cmd\0";

echo "<p  style='color:red' >Demo HTTP Client:$message <BR></p>";
echo "<p  style='color:red' >Send TCP command...<BR>[".$message."]<BR><BR></p>";

$socket = socket_create(AF_INET, SOCK_STREAM, 0) or die("from Client: Could not create socket\n");
$result = socket_connect($socket, $ip, $port) or die("from Client: Unable to connect to server\n");


socket_write($socket, $message, strlen($message));

$input = socket_read($socket, 1024);
echo $input;

?>



<?php
echo "<p  style='color:red' >Respones... <BR></p>";

$r_data="";

$data = "";
$done = false;
$total=0;
$bb=1;

do{

 
    socket_clear_error($socket);
    $bytes = socket_recv($socket, $r_data, 1256, MSG_WAITALL);//MSG_DONTWAIT

    $lastError = socket_last_error($socket);


    $bb=intval($bytes);

    $total=$total+$bb;

    if ($lastError != 11 && $lastError > 0) {
        // something went wrong! do something
        echo "Wrong";
        $done = true;
    }
    else if ($bb==0){
        
        continue;
    }
    else if ($bb > 0) {

    
        $data=$data.$r_data;
        //echo $data;
    }
    else {
        usleep(2000); // prevent "CPU burn"
    }
}while($bb>0);

echo "<p  style='color:red' >Total=$total bytes<BR></p>";
echo nl2br($data);

echo "<BR>";

sleep(1);

socket_close($socket);
date_default_timezone_set('Asia/Taipei');
$today=date('m/d/Y h:i:s a', time());;
echo "\n<BR><p  style='color:red' > Bye from Client...[$today]</p>";

}


?>


</body>
</html>

不要認為 PHP 很難, 我的經驗是當時我當最後一關 面試委員, 候選 3 人都沒學過PHP, 我早上同時 教3人, 下午考~就有一人 可以, 因為他 基礎好, 所以基礎很重要, 尤其 團隊合作, 計概(含 c 語言), 微處理機, 資料結構…

PHP 請自學

PHP 很多網路上的例子~很多 方便 學習, 實務上要考量 美工與前端 JavaScript 的 配合~因此 要 考慮 很多, 很多例子要 修改別亂抄!