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// SPDX-License-Identifier: GPL-2.0
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#define PORT 12345
#define RUNTIME 10
static struct {
unsigned int timeout;
unsigned int port;
} opts = {
.timeout = RUNTIME,
.port = PORT,
};
static void handler(int sig)
{
_exit(sig == SIGALRM ? 0 : 1);
}
static void set_timeout(void)
{
struct sigaction action = {
.sa_handler = handler,
};
sigaction(SIGALRM, &action, NULL);
alarm(opts.timeout);
}
static void do_connect(const struct sockaddr_in *dst)
{
int s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (s >= 0)
fcntl(s, F_SETFL, O_NONBLOCK);
connect(s, (struct sockaddr *)dst, sizeof(*dst));
close(s);
}
static void do_accept(const struct sockaddr_in *src)
{
int c, one = 1, s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (s < 0)
return;
setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
bind(s, (struct sockaddr *)src, sizeof(*src));
listen(s, 16);
c = accept(s, NULL, NULL);
if (c >= 0)
close(c);
close(s);
}
static int accept_loop(void)
{
struct sockaddr_in src = {
.sin_family = AF_INET,
.sin_port = htons(opts.port),
};
inet_pton(AF_INET, "127.0.0.1", &src.sin_addr);
set_timeout();
for (;;)
do_accept(&src);
return 1;
}
static int connect_loop(void)
{
struct sockaddr_in dst = {
.sin_family = AF_INET,
.sin_port = htons(opts.port),
};
inet_pton(AF_INET, "127.0.0.1", &dst.sin_addr);
set_timeout();
for (;;)
do_connect(&dst);
return 1;
}
static void parse_opts(int argc, char **argv)
{
int c;
while ((c = getopt(argc, argv, "t:p:")) != -1) {
switch (c) {
case 't':
opts.timeout = atoi(optarg);
break;
case 'p':
opts.port = atoi(optarg);
break;
}
}
}
int main(int argc, char *argv[])
{
pid_t p;
parse_opts(argc, argv);
p = fork();
if (p < 0)
return 111;
if (p > 0)
return accept_loop();
return connect_loop();
}
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