test07_srv.c

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/*
 * Test name: test07_srv.c
 *
 * Objective: Test an impatient TCP server with a timeout.
 *
 * Description: Implements an echo server using the TCP protocol. It is
 * based on test06_srv.c but has a timeout for receiving data from a client
 * and if the time is up it sends an angry message to the client requesting
 * for more information.
 */

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/select.h>
#include <sys/wait.h>
#include <sys/asynchio.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <net/netlib.h>
#include <net/gen/netdb.h>
#include <net/gen/in.h>
#include <net/gen/tcp.h>
#include <net/gen/tcp_io.h>
#include <net/hton.h>
#include <net/gen/inet.h>

#define PORT 6060L

int listen(long port) {

  char *tcp_device;
  int netfd;
  nwio_tcpconf_t tcpconf;
  nwio_tcpcl_t tcplistenopt;
                            
  /* Get default UDP device */
  if ((tcp_device = getenv("TCP_DEVICE")) == NULL) 
    tcp_device = TCP_DEVICE;
                                
  /* Open TCP connection */ 
  if ((netfd = open(tcp_device, O_RDWR)) < 0) 
  {
    fprintf(stderr,"Error opening TCP connection\n");
    return -1;
  }               
                                
  /* Configure TCP connection */ 
  tcpconf.nwtc_flags = NWTC_LP_SET | NWTC_UNSET_RA | NWTC_UNSET_RP;
  tcpconf.nwtc_locport = (tcpport_t) htons(port);
                                
  if ((ioctl(netfd, NWIOSTCPCONF, &tcpconf))<0) 
  {
    fprintf(stderr,"Error configuring the connection\n");
    close(netfd);
    return -1;
  }               

  /* Get communication options */
  if ((ioctl(netfd, NWIOGTCPCONF, &tcpconf)) < 0) {
    fprintf(stderr, "Error getting configuration\n");
    close(netfd);
    return -1;
   }                
                                
  /* Set conf options */
  tcplistenopt.nwtcl_flags = 0;
  printf("Waiting for connections...\n");
  while ((ioctl(netfd, NWIOTCPLISTEN, &tcplistenopt)) == -1) 
  {
    if (errno != EAGAIN)
    {
        fprintf(stderr,"Unable to listen for connections\n");
        close(netfd);
    }
    sleep(-1);
  }               
  return netfd;
}

int main(int argc,char *argv[]) {
  int fd;
  ssize_t data_read;
  char buffer[1024];
  int ret;
  fd_set fds_read;
  struct timeval timeout;

  if ((fd = listen(PORT)) < 0) {
        exit(-1);       
  }
  printf("Waiting for messages on port: %ld\n", PORT);
  fflush(stdout);
  while (1) 
  {

    /* Initialize fd_set */
    FD_ZERO(&fds_read);
    FD_SET(fd, &fds_read);
    /* set timeout */
    timeout.tv_sec = 3;
    timeout.tv_usec = 0;
    /* Wait for data available to be read (no timeout) */
    ret = select(4, &fds_read, NULL, NULL, &timeout);
    if (ret < 0) {
        fprintf(stderr, "Error on select: %d\n", errno);
        exit(-1);
    }
    /* timeout */
    if (ret == 0) {
        strcpy(buffer, "I want to get some data!!\n");
        write(fd, &buffer, 1024);
        continue;
    }

    /* data received from client */
    if (FD_ISSET(fd, &fds_read)) {
        printf("Ready to receive...\n");
        /* Read received data */
        data_read = read(fd, &buffer, 1024);
        printf("Received data: %s\n", buffer);
                                
        /* Can exit if the received string == exit */
        if (!strcmp(buffer,"exit")) 
           break; 

        /* Write the same back  */
        write(fd, &buffer, data_read);             
     }               
  }                       
  printf("Connection finished\n");
  close(fd);
}

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