#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <memory.h>
#include <errno.h>
#include <arpa/inet.h>
#include <unistd.h>
#define MAX_CLIENT 32
#define SERVER_PORT_NUM 2000
struct test_struct{
unsigned int a;
unsigned int b;
};
struct res_struct{
unsigned int c;
} ;
char buff[1024];
int monitoring_fd_set[32];
static void
init_monitor_fd_set(){
int i = 0;
for(; i < MAX_CLIENT; i++)
monitoring_fd_set[i] = -1;
}
static void
add_monitoring_fd_set(int soc_fd){
int i = 0;
for(; i < MAX_CLIENT; i++){
if(monitoring_fd_set[i] != -1)
continue;
monitoring_fd_set[i] = soc_fd;
break;
}
}
static void
remove_monitoring_fd_set(int soc_fd){
int i = 0;
for(; i < MAX_CLIENT; i++){
if(monitoring_fd_set[i] != soc_fd)
continue;
monitoring_fd_set[i] = -1;
break;
}
}
static void
re_init_fds(fd_set *fd_set){
FD_ZERO(fd_set);
int i = 0;
for(; i < MAX_CLIENT; i++){
if(monitoring_fd_set[i] != -1){
FD_SET(monitoring_fd_set[i], fd_set);
}
}
}
static int
max_fd(){
int i = 0;
int max = -1;
for(; i < MAX_CLIENT; i++){
if(monitoring_fd_set[i] > max)
max = monitoring_fd_set[i];
}
return max;
}
void tcp_server(){
int master_sock_fd = 0, recv_bytes = 0, addr_len = 0, opt = 1;
int commu_socket_fd = 0;
fd_set read_fds;
struct sockaddr_in srv_addr, cli_addr;
init_monitor_fd_set();
if ((master_sock_fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP )) == -1)
{
printf("socket creation failed\n");
exit(1);
}
srv_addr.sin_family = AF_INET;
srv_addr.sin_port = SERVER_PORT_NUM;
srv_addr.sin_addr.s_addr = INADDR_ANY;
addr_len = sizeof(struct sockaddr);
if (bind(master_sock_fd, (struct sockaddr *)&srv_addr, sizeof(struct sockaddr)) == -1)
{
printf("bind failed\n");
return;
}
if (listen(master_sock_fd, 5)<0)
{
printf("listen failed\n");
return;
}
add_monitoring_fd_set(master_sock_fd);
while(1){
re_init_fds(&read_fds);
select(max_fd() + 1, &read_fds, NULL, NULL, NULL);
if (FD_ISSET(master_sock_fd, &read_fds))
{
commu_socket_fd = accept(master_sock_fd, (struct sockaddr *)&cli_addr, &addr_len);
if(commu_socket_fd < 0){
printf("accept error : errno = %d\n", errno);
exit(0);
}
add_monitoring_fd_set(commu_socket_fd);
}
else
{
int i = 0, commu_socket_fd = -1;
for(; i < MAX_CLIENT; i++){
if(FD_ISSET(monitoring_fd_set[i], &read_fds)){
commu_socket_fd = monitoring_fd_set[i];
memset(buff, 0, sizeof(buff));
recv_bytes = recvfrom(commu_socket_fd, (char *)buff, sizeof(buff), 0, (struct sockaddr *)&cli_addr, &addr_len);
if(recv_bytes == 0){
close(commu_socket_fd);
remove_monitoring_fd_set(commu_socket_fd);
break;
}
struct test_struct *client_data = (struct test_struct *)buff;
if(client_data->a == 0 && client_data->b ==0){
close(commu_socket_fd);
remove_monitoring_fd_set(commu_socket_fd);
printf("Server closes client connection : %s:%u\n", inet_ntoa(cli_addr.sin_addr), ntohs(cli_addr.sin_port));
break;
}
struct res_struct result;
result.c = client_data->a + client_data->b;
recv_bytes = sendto(commu_socket_fd, (char *)&result, sizeof(struct res_struct), 0,
(struct sockaddr *)&cli_addr, sizeof(struct sockaddr));
}
}
}
}
}
int
main(int argc, char **argv){
tcp_server();
return 0;
}
