GTK with tcp/ip socket: how can you do both?

I put together a quick program from tutorials that acts like a server listening on a socket. The program pauses on the line

n = read(newsockfd,buffer,255);

I wanted to add a window to this program with gtk, but I realized I don't know how to have both together. As gtk_main() also causes the program to pause...

How can you have a gtk window and have the program listen on a socket?

Code:

#include <stdio.h>
#include <sys/types.h> 
#include <sys/socket.h>
#include <netinet/in.h>
#include <gtk/gtk.h>

void error(char *msg)
{
    perror(msg);
    exit(1);
}

unsigned char readSocket(){
     unsigned char temp;
     int sockfd, newsockfd, portno, clilen;
     char buffer[256];
     struct sockaddr_in serv_addr, cli_addr;
     int n;
     sockfd = socket(AF_INET, SOCK_STREAM, 0);
     if (sockfd < 0) 
        error("ERROR opening socket");
     bzero((char *) &serv_addr, sizeof(serv_addr));
     portno = atoi("60000");
     serv_addr.sin_family = AF_INET;
     serv_addr.sin_addr.s_addr = INADDR_ANY;
     serv_addr.sin_port = htons(portno);
     if (bind(sockfd, (struct sockaddr *) &serv_addr,
              sizeof(serv_addr)) < 0) 
              error("ERROR on binding");
     listen(sockfd,5);
     
     for(;;){
     clilen = sizeof(cli_addr);
     newsockfd = accept(sockfd, 
                 (struct sockaddr *) &cli_addr, 
                 &clilen);
     if (newsockfd < 0) 
          error("ERROR on accept");
     bzero(buffer,256);
     n = read(newsockfd,buffer,255);
     if (n < 0) error("ERROR reading from socket");
     printf("%s",buffer);

     close(newsockfd);
     }
     return 0;

}

int main(int argc, char *argv[])
{
   
  GtkWidget *window;

  gtk_init(&argc, &argv);

  window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
  gtk_widget_show(window);

  gtk_main();

  readSocket();  
    
     return 0; 
}