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* Copyright (c) 2017 Linaro Limited
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <stdio.h>
#include <stdbool.h>
#include <errno.h>
#include <stdlib.h>
#ifndef __ZEPHYR__
#include <netinet/in.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <fcntl.h>
#else
#include <fcntl.h>
#include <net/socket.h>
#include <kernel.h>
#endif
/* For Zephyr, keep max number of fd's in sync with max poll() capacity */
#ifdef CONFIG_NET_SOCKETS_POLL_MAX
#define NUM_FDS CONFIG_NET_SOCKETS_POLL_MAX
#else
#define NUM_FDS 5
#endif
#define PORT 4242
/* Number of simultaneous client connections will be NUM_FDS be minus 2 */
fd_set readfds;
fd_set workfds;
int fdnum;
#define fatal(msg, ...) { \
printf("Error: " msg "\n", ##__VA_ARGS__); \
exit(1); \
}
static void setblocking(int fd, bool val)
{
int fl, res;
fl = fcntl(fd, F_GETFL, 0);
if (fl == -1) {
fatal("fcntl(F_GETFL): %d", errno);
}
if (val) {
fl &= ~O_NONBLOCK;
} else {
fl |= O_NONBLOCK;
}
res = fcntl(fd, F_SETFL, fl);
if (fl == -1) {
fatal("fcntl(F_SETFL): %d", errno);
}
}
int pollfds_add(int fd)
{
FD_SET(fd, &readfds);
if (fd >= fdnum) {
fdnum = fd + 1;
}
return 0;
}
void pollfds_del(int fd)
{
FD_CLR(fd, &readfds);
}
int main(void)
{
int res;
static int counter;
int serv4, serv6;
struct sockaddr_in bind_addr4 = {
.sin_family = AF_INET,
.sin_port = htons(PORT),
.sin_addr = {
.s_addr = htonl(INADDR_ANY),
},
};
struct sockaddr_in6 bind_addr6 = {
.sin6_family = AF_INET6,
.sin6_port = htons(PORT),
.sin6_addr = IN6ADDR_ANY_INIT,
};
serv4 = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (serv4 < 0) {
printf("error: socket: %d\n", errno);
exit(1);
}
res = bind(serv4, (struct sockaddr *)&bind_addr4, sizeof(bind_addr4));
if (res == -1) {
printf("Cannot bind IPv4, errno: %d\n", errno);
}
serv6 = socket(AF_INET6, SOCK_STREAM, IPPROTO_TCP);
if (serv6 < 0) {
printf("error: socket(AF_INET6): %d\n", errno);
exit(1);
}
#ifdef IPV6_V6ONLY
/* For Linux, we need to make socket IPv6-only to bind it to the
* same port as IPv4 socket above.
*/
int TRUE = 1;
res = setsockopt(serv6, IPPROTO_IPV6, IPV6_V6ONLY, &TRUE, sizeof(TRUE));
if (res < 0) {
printf("error: setsockopt: %d\n", errno);
exit(1);
}
#endif
res = bind(serv6, (struct sockaddr *)&bind_addr6, sizeof(bind_addr6));
if (res == -1) {
printf("Cannot bind IPv6, errno: %d\n", errno);
}
FD_ZERO(&readfds);
setblocking(serv4, false);
setblocking(serv6, false);
listen(serv4, 5);
listen(serv6, 5);
pollfds_add(serv4);
pollfds_add(serv6);
printf("Async select-based TCP echo server waits for connections on port %d...\n", PORT);
while (1) {
struct sockaddr_storage client_addr;
socklen_t client_addr_len = sizeof(client_addr);
char addr_str[32];
/* As select overwrites passed fd_set, we run it against
* temporary fd_set, by first copying a real fd_set into it.
*/
workfds = readfds;
res = select(fdnum, &workfds, NULL, NULL, NULL);
if (res == -1) {
printf("select error: %d\n", errno);
continue;
}
for (int i = 0; i < fdnum; i++) {
if (!FD_ISSET(i, &workfds)) {
continue;
}
int fd = i;
if (fd == serv4 || fd == serv6) {
/* If server socket */
int client = accept(fd, (struct sockaddr *)&client_addr,
&client_addr_len);
void *addr = &((struct sockaddr_in *)&client_addr)->sin_addr;
inet_ntop(client_addr.ss_family, addr,
addr_str, sizeof(addr_str));
printf("Connection #%d from %s fd=%d\n", counter++,
addr_str, client);
if (pollfds_add(client) < 0) {
static char msg[] = "Too many connections\n";
send(client, msg, sizeof(msg) - 1, 0);
close(client);
} else {
setblocking(client, false);
}
} else {
char buf[128];
int len = recv(fd, buf, sizeof(buf), 0);
if (len <= 0) {
if (len < 0) {
printf("error: recv: %d\n", errno);
}
error:
pollfds_del(fd);
close(fd);
printf("Connection fd=%d closed\n", fd);
} else {
int out_len;
const char *p;
/* We implement semi-async server,
* where reads are async, but writes
* *can* be sync (blocking). Note that
* in majority of cases they expected
* to not block, but to be robust, we
* handle all possibilities.
*/
setblocking(fd, true);
for (p = buf; len; len -= out_len) {
out_len = send(fd, p, len, 0);
if (out_len < 0) {
printf("error: "
"send: %d\n",
errno);
goto error;
}
p += out_len;
}
setblocking(fd, false);
}
}
}
}
}
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