duct/main.c

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C
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2022-09-14 10:07:25 +03:00
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <poll.h>
#include <unistd.h>
#define MAX_CLIENTS 512
#define BACKLOG 10
#define DIE(info) ({perror((info)); exit(EXIT_FAILURE);})
static const char *socket_path = "/tmp/plumb-unix0";
struct plumb_client {
int fd;
};
struct plumb_server {
int socket_fd;
int fd_num;
struct plumb_client clients[MAX_CLIENTS];
struct pollfd fds[MAX_CLIENTS + 1];
};
int plumb_server_client_add(struct plumb_server *s, int fd)
{
printf("adding new connection, fd=%d\n", fd);
for (int i = 0; i < MAX_CLIENTS; i++) {
if (s->clients[i].fd < 0) {
s->clients[i].fd = fd;
s->fds[i].fd = fd;
s->fds[i].events = POLLIN;
return i;
}
}
return -1;
}
void plumb_server_client_remove(struct plumb_server *s, int i)
{
if (i >= MAX_CLIENTS)
return;
printf("removing client i=%d\n", i);
if (s->clients[i].fd >= 0) {
close(s->clients[i].fd);
}
s->clients[i].fd = -1;
s->fds[i].fd = -1;
s->fds[i].events = 0;
s->fds[i].revents = 0;
}
void plumb_server_free(struct plumb_server *s)
{
if (!s) return;
if (s->socket_fd) close(s->socket_fd);
free(s);
}
struct plumb_server *plumb_server_create()
{
struct plumb_server *s = malloc(sizeof(struct plumb_server));
if (s == NULL) {
DIE("malloc");
return NULL;
}
s->socket_fd = socket(AF_UNIX, SOCK_STREAM, 0);
if (s->socket_fd == -1) {
free(s);
DIE("socket");
return NULL;
}
struct sockaddr_un name;
memset(&name, 0, sizeof(name));
name.sun_family = AF_UNIX;
strncpy(name.sun_path, socket_path, sizeof(name.sun_path) - 1);
if (bind(s->socket_fd, (const struct sockaddr *)&name, sizeof(name)) == -1) {
free(s);
close(s->socket_fd);
DIE("bind");
return NULL;
}
if (listen(s->socket_fd, BACKLOG) == -1) {
free(s);
close(s->socket_fd);
DIE("listen");
return NULL;
}
for (int i = 0; i < MAX_CLIENTS; i++) {
s->clients[i].fd = -1;
s->fds[i].fd = -1;
s->fds[i].events = 0;
s->fds[i].revents = 0;
}
s->fds[MAX_CLIENTS].fd = s->socket_fd;
s->fds[MAX_CLIENTS].events = POLLIN;
s->fd_num = MAX_CLIENTS + 1;
return s;
}
int plumb_server_turn(struct plumb_server *s)
{
if (poll(s->fds, s->fd_num, -1) < 0) {
DIE("poll");
return -1;
}
for (int i = 0; i < s->fd_num; i++) {
if (s->fds[i].revents & POLLIN) { // file descriptor ready for reading
if (s->fds[i].fd == s->socket_fd) { // new connection
int fd = accept(s->socket_fd, NULL, NULL);
if (fd == -1) {
DIE("accept");
return -1;
}
if (plumb_server_client_add(s, fd) == -1) {
close(fd);
continue;
}
} else { // data from socket
char data[256];
memset(data, 0, sizeof(data));
ssize_t bytes = recv(s->fds[i].fd, data, sizeof(data), 0);
if (bytes == -1) {
DIE("recv");
return -1;
} else if (bytes == 0) { // client disconnected
plumb_server_client_remove(s, i);
} else {
send(s->fds[i].fd, data, sizeof(data), 0);
}
}
}
}
return 0;
}
int main()
{
struct plumb_server *srv = plumb_server_create();
if (srv == NULL) {
fprintf(stderr, "plumb_server_create failed\n");
return EXIT_FAILURE;
}
while (1) {
if (plumb_server_turn(srv) < 0) {
fprintf(stderr, "plumb_server_turn failed\n");
plumb_server_free(srv);
return EXIT_FAILURE;
}
}
plumb_server_free(srv);
return EXIT_SUCCESS;
}