some-usable-scripts/c/libipc/test-select.c

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C
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2020-01-28 12:41:11 +01:00
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int setup_tcp_socket(short int port)
{
/* server address */
struct sockaddr_in serveraddr;
memset(&serveraddr, 0, sizeof(struct sockaddr_in));
socklen_t addrlen = sizeof(struct sockaddr_in);
/* for setsockopt() SO_REUSEADDR, below */
int yes = 1;
int listener = -1;
if((listener = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == -1) {
perror("Server-socket()");
exit(1);
}
printf("Server-socket() is OK... fd %d\n", listener);
/*"address already in use" error message */
if(setsockopt(listener
, SOL_SOCKET
, SO_REUSEADDR
, &yes
, sizeof(int)) == -1) {
perror("Server-setsockopt()");
exit(1);
}
printf("Server-setsockopt() is OK...\n");
/* bind */
serveraddr.sin_family = AF_INET;
serveraddr.sin_port = htons(port);
serveraddr.sin_addr.s_addr = INADDR_ANY;
// memset(&(serveraddr.sin_zero), '\0', 8);
if(bind(listener, (struct sockaddr *)&serveraddr, addrlen) == -1) {
perror("Server-bind()");
exit(1);
}
printf("Server-bind() is OK...\n");
/* listen */
if(listen(listener, 10) == -1)
{
perror("Server-listen()");
exit(1);
}
printf("Server-listen() is OK...\n");
return listener;
}
int main(int argc, char * argv[])
{
if (argc < 2) {
fprintf (stderr, "usage: %s port\n", argv[0]);
exit(1);
}
short int port = atoi(argv[1]);
printf ("port : %d\n", port);
/* client address */
struct sockaddr_in clientaddr;
memset(&clientaddr, 0, sizeof(struct sockaddr_in));
/* master file descriptor list */
fd_set master;
/* temp file descriptor list for select() */
fd_set read_fds;
/* maximum file descriptor number */
int fdmax;
/* listening socket descriptor */
// int listener = open ("/tmp/bla", O_RDONLY);
int listener;
int newfd;
/* buffer for client data */
char buf[6];
int nbytes;
socklen_t addrlen;
int i, j;
/* Now we set variables */
listener = setup_tcp_socket (port);
/* clear the master and temp sets */
FD_ZERO(&master);
FD_ZERO(&read_fds);
/* add the listener to the master set */
FD_SET(listener, &master);
/* keep track of the biggest file descriptor */
fdmax = listener; /* so far, it's this one*/
int times_going_in_select = 0;
/* loop */
for(;;) {
/* copy it */
read_fds = master;
if(select(fdmax+1, &read_fds, NULL, NULL, NULL) == -1)
{
perror("Server-select() error lol!");
exit(1);
}
times_going_in_select++;
// printf("Server-select() is OK... message received\n");
/*run through the existing connections looking for data to be read*/
for(i = 0; i <= fdmax; i++) {
if(FD_ISSET(i, &read_fds)) {
/* we got one... */
if(i == listener) {
printf("new connection");
/* handle new connections */
addrlen = sizeof(clientaddr);
if((newfd = accept(listener, (struct sockaddr *)&clientaddr, &addrlen)) == -1) {
perror("Server-accept()");
}
else
{
printf("Server-accept() is OK...\n");
FD_SET(newfd, &master); /* add to master set */
if(newfd > fdmax)
{ /* keep track of the maximum */
fdmax = newfd;
}
printf("%s: New connection from %s on socket %d\n"
, argv[0], inet_ntoa(clientaddr.sin_addr), newfd);
}
}
else {
/* handle data from a client */
if((nbytes = recv(i, buf, sizeof(buf), 0)) <= 0) {
/* got error or connection closed by client */
if(nbytes == 0)
/* connection closed */
printf("%s: socket %d hung up\n", argv[0], i);
else
perror("recv() error lol!");
/* close it... */
close(i);
/* remove from master set */
FD_CLR(i, &master);
}
else {
printf("received message: %s (%d going in select function)\n", buf, times_going_in_select);
/* we got some data from a client*/
for(j = 0; j <= fdmax; j++) {
/* send to everyone! */
if(FD_ISSET(j, &master)) {
#if 0
/* except the listener and ourselves */
if(j != listener && j != i)
#endif
/* except the listener */
if(j != listener) {
if(send(j, buf, nbytes, 0) == -1)
perror("send() error lol!");
}
}
}
}
}
}
}
}
return EXIT_SUCCESS;
}