Server port doenst go back to listen and is in closed_wait state , because of starting an daemon application from client

Question

Below is the basic client and server code . While iam trying to start an appliaction(which has to keep running in the machine once we send a msg to server) during connect call. using system(/bin/myApplication) in the client code (This basically is a simple c executable with an infinite loop,assuming my application has to be running); Once iam starting the application the server is in CLOSED_WAIT State and its coming back to listen only if i stop this application . The issue is with the server socket in CLOSED_WAIT state, Is there a way that this application keep running as a seperate process and server would be in listen state again. Client Code: There is a system command after read.and it starts an application(basically is an c executable with an infinite while loop)

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

int main(int argc, char *argv[])
{
int sockfd = 0, n = 0;
char recvBuff[1024];
struct sockaddr_in serv_addr; 

if(argc != 2)
  {
    printf("\n Usage: %s <ip of server> \n",argv[0]);
    return 1;
} 

memset(recvBuff, '0',sizeof(recvBuff));
if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
    printf("\n Error : Could not create socket \n");
    return 1;
} 

memset(&serv_addr, '0', sizeof(serv_addr)); 

serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(5000); 

if(inet_pton(AF_INET, argv[1], &serv_addr.sin_addr)<=0)
{
    printf("\n inet_pton error occured\n");
    return 1;
} 

if( connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
{
   printf("\n Error : Connect Failed \n");
   return 1;
} 

while ( (n = read(sockfd, recvBuff, sizeof(recvBuff)-1)) > 0)
{
    recvBuff[n] = 0;
    if(fputs(recvBuff, stdout) == EOF)
    {
        printf("\n Error : Fputs error\n");
    }
} 
system(/bin/myApplication);
if(n < 0)
{
    printf("\n Read error \n");
} 

return 0;

Server Code:

int main(int argc, char *argv[])
{
int listenfd = 0, connfd = 0;
struct sockaddr_in serv_addr; 

char sendBuff[1025];
time_t ticks; 

listenfd = socket(AF_INET, SOCK_STREAM, 0);
memset(&serv_addr, '0', sizeof(serv_addr));
memset(sendBuff, '0', sizeof(sendBuff)); 

serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
serv_addr.sin_port = htons(5000); 

bind(listenfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)); 

listen(listenfd, 10); 

while(1)
{
    connfd = accept(listenfd, (struct sockaddr*)NULL, NULL); 

    ticks = time(NULL);
    snprintf(sendBuff, sizeof(sendBuff), "%.24s\r\n", ctime(&ticks));
    write(connfd, sendBuff, strlen(sendBuff)); 

    close(connfd);
    sleep(1);
 }

}

My Sample Application,which is a c file with while loop int main(int argc, char *argv[]) {

while(1)

{

}
return 1;
}
gcc myApplicaion.c -o myApplication

I have tried using fork , but still the socket is in same state , is there anyway that this application runs seperately and doesnt effect the socket nor does it depend on the parent process(Server here).

Answer 1

Did you try to close the socket in your client before running 'myApplication'?

while ( (n = read(sockfd, recvBuff, sizeof(recvBuff)-1)) > 0)
{
    recvBuff[n] = 0;
    if(fputs(recvBuff, stdout) == EOF)
    {
        printf("\n Error : Fputs error\n");
    }
} 
/* close the socket here*/
close(sockfd);

system(/bin/myApplication);