/***********************************************************************/
/* */
/* */
/* */
/* */
/* This program uses the Select function to control sockets */
/* First, the vectors of file descriptors (fd) will be set in order to */
/* load the select function with the appropriate fds. */
/* */
/* The select command accepts 4 parameters: */
/* - fds that are load for reading */
/* - fds that are load for writing */
/* - fds that are load for exception handling */
/* */
/* after the connection is established an iinfinite loop with the */
/* client work permanently. */
/* */
/* */
/* */
/* */
/* */
/* */
/* */
/* */
/* */
/* */
/* */
/* */
/***********************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <unistd.h>
#define MYPORT 3490 /* the port users will be connecting to */
#define MAXDATASIZE 100 /*The maximum message passed */
#define BACKLOG 10 /* how many pending connections queue will hold */
main()
{
struct sockaddr_in my_addr; /*My address information */
struct sockaddr_in their_addr; /*Connector's address information */
struct timeval tv; /*The time wait for socket to be changed */
struct timezone tz; /*The time zone we are using */
struct timeval measure_tv_before; /*The time wait for socket to be changed */
struct timezone measure_tz_before; /*The time zone we are using */
struct timeval measure_tv_after; /*The time wait for socket to be changed */
struct timezone measure_tz_after; /*The time zone we are using */
fd_set readfds, writefds, exceptfds; /*File descriptors for read, write and exceptions */
int new_fd; /*The new file descriptor returned from accept */
int sockfd; /*The first file descriptor given for communication*/
int j; /*Index used for fd counter */
int sin_size; /*Size of struct internet input address */
int numbytes; /* Number of bytes received in each packet */
int sock;
int sock_to_read; /* File descriptor ready for reading */
int max_fd; /* Number of socket fd that are in use */
char buf[MAXDATASIZE]; /*The string to be passed */
/*Initiate the read, write, except structs */
FD_ZERO(&readfds);
FD_ZERO(&writefds);
FD_ZERO(&exceptfds);
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
perror("socket");
exit(1);
}
my_addr.sin_family = AF_INET; /* host byte order */
my_addr.sin_port = htons(MYPORT); /* short, network byte order */
my_addr.sin_addr.s_addr = INADDR_ANY; /* auto-fill with my IP */
bzero(&(my_addr.sin_zero), 8); /* zero the rest of the struct */
if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr)) \
== -1) {
perror("bind");
exit(1);
}
if (listen(sockfd, BACKLOG) == -1) {
perror("listen");
exit(1);
}
max_fd = sockfd;
FD_SET(sockfd, &readfds); /*Add sock_fd to the set of file descriptors to read from */
FD_ZERO(&readfds);
FD_ZERO(&writefds);
FD_ZERO(&exceptfds);
for(j=sockfd;j<=max_fd;j++){
FD_SET(j,&readfds);
printf ("Setup fd number %d \n",j);
}
while(1) { /* main accept() loop */
/*--------------------------------------*/
/* Initiate the FD vector & set values */
/*--------------------------------------*/
gettimeofday(&measure_tv_before,&measure_tz_before);
printf("Before select ...time is: %ld, %ld\n",tv.tv_sec,tv.tv_usec);
tv.tv_sec = 5; /*Initiate time to wait for fd to change */
if ((sock = select(max_fd+1 , &readfds, &writefds, &exceptfds, &tv)) < 0) {
perror("select");
continue;
}
gettimeofday(&measure_tv_after,&measure_tz_after);
printf("After select again...time in select: %ld sec and %ld usec\n", \
measure_tv_after.tv_sec - measure_tv_before.tv_sec ,measure_tv_after.tv_usec - measure_tv_before.tv_usec);
printf("Sock value is (after select) :%d \n",sock);
/*Checking which FD are set */
if(FD_ISSET(sockfd, &readfds)){ /* If sockfd is changed, new conenciton is requested */
/* Reading and writing is done to other fds */
if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr, \
&sin_size)) == -1) {
perror("accept");
continue;
}
max_fd = new_fd;
printf("server: got connection from %s\n", \
inet_ntoa(their_addr.sin_addr));
FD_SET(new_fd, &readfds); /*Add sock_fd to the set of file descriptors to read from */
FD_CLR(sockfd, &readfds); /*Add sock_fd to the set of file descriptors to read from */
printf("Ending the connect function %ld, %ld\n",tv.tv_sec,tv.tv_usec);
}
else {
/*Check which FD are set */
for (j=sockfd;j<=max_fd && sock > 0;j++){ /*The loop starts from the first comm fd */
printf("Checking now j=%d, readfs(j) status =%d \n", j, FD_ISSET(j, &readfds));
if (FD_ISSET(j, &readfds) == 1 ) {
sock_to_read = j;
if ((numbytes=recv(sock_to_read, buf, MAXDATASIZE, 0)) == -1) {/*Receive info from the server*/
perror("recv");
exit(1);
}
buf[numbytes] = '\0';
printf("recv: sock=%d, buf=%s \n", sock,buf);
if (send(sock_to_read , "Hello, world!\n", 14, 0) == -1)
perror("send in loop");
FD_CLR(sock_to_read, &readfds);
sock--; /* We found one fd that was changed form select */
for(j=sockfd;j<=max_fd;j++)
FD_SET(j,&readfds);
}
}
}
}
close(new_fd);
}