1 // SPDX-License-Identifier: GPL-2.0
2 
3 #include <arpa/inet.h>
4 #include <errno.h>
5 #include <error.h>
6 #include <netinet/in.h>
7 #include <netinet/tcp.h>
8 #include <signal.h>
9 #include <stdio.h>
10 #include <stdlib.h>
11 #include <sys/socket.h>
12 #include <sys/time.h>
13 #include <unistd.h>
14 
15 static int child_pid;
16 
timediff(struct timeval s,struct timeval e)17 static unsigned long timediff(struct timeval s, struct timeval e)
18 {
19 	unsigned long s_us, e_us;
20 
21 	s_us = s.tv_sec * 1000000 + s.tv_usec;
22 	e_us = e.tv_sec * 1000000 + e.tv_usec;
23 	if (s_us > e_us)
24 		return 0;
25 	return e_us - s_us;
26 }
27 
client(int port)28 static void client(int port)
29 {
30 	int sock = 0;
31 	struct sockaddr_in addr, laddr;
32 	socklen_t len = sizeof(laddr);
33 	struct linger sl;
34 	int flag = 1;
35 	int buffer;
36 	struct timeval start, end;
37 	unsigned long lat, sum_lat = 0, nr_lat = 0;
38 
39 	while (1) {
40 		gettimeofday(&start, NULL);
41 
42 		sock = socket(AF_INET, SOCK_STREAM, 0);
43 		if (sock < 0)
44 			error(-1, errno, "socket creation");
45 
46 		sl.l_onoff = 1;
47 		sl.l_linger = 0;
48 		if (setsockopt(sock, SOL_SOCKET, SO_LINGER, &sl, sizeof(sl)))
49 			error(-1, errno, "setsockopt(linger)");
50 
51 		if (setsockopt(sock, IPPROTO_TCP, TCP_NODELAY,
52 					&flag, sizeof(flag)))
53 			error(-1, errno, "setsockopt(nodelay)");
54 
55 		addr.sin_family = AF_INET;
56 		addr.sin_port = htons(port);
57 
58 		if (inet_pton(AF_INET, "127.0.0.1", &addr.sin_addr) <= 0)
59 			error(-1, errno, "inet_pton");
60 
61 		if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0)
62 			error(-1, errno, "connect");
63 
64 		send(sock, &buffer, sizeof(buffer), 0);
65 		if (read(sock, &buffer, sizeof(buffer)) == -1)
66 			error(-1, errno, "waiting read");
67 
68 		gettimeofday(&end, NULL);
69 		lat = timediff(start, end);
70 		sum_lat += lat;
71 		nr_lat++;
72 		if (lat < 100000)
73 			goto close;
74 
75 		if (getsockname(sock, (struct sockaddr *)&laddr, &len) == -1)
76 			error(-1, errno, "getsockname");
77 		printf("port: %d, lat: %lu, avg: %lu, nr: %lu\n",
78 				ntohs(laddr.sin_port), lat,
79 				sum_lat / nr_lat, nr_lat);
80 close:
81 		fflush(stdout);
82 		close(sock);
83 	}
84 }
85 
server(int sock,struct sockaddr_in address)86 static void server(int sock, struct sockaddr_in address)
87 {
88 	int accepted;
89 	int addrlen = sizeof(address);
90 	int buffer;
91 
92 	while (1) {
93 		accepted = accept(sock, (struct sockaddr *)&address,
94 				(socklen_t *)&addrlen);
95 		if (accepted < 0)
96 			error(-1, errno, "accept");
97 
98 		if (read(accepted, &buffer, sizeof(buffer)) == -1)
99 			error(-1, errno, "read");
100 		close(accepted);
101 	}
102 }
103 
sig_handler(int signum)104 static void sig_handler(int signum)
105 {
106 	kill(SIGTERM, child_pid);
107 	exit(0);
108 }
109 
main(int argc,char const * argv[])110 int main(int argc, char const *argv[])
111 {
112 	int sock;
113 	int opt = 1;
114 	struct sockaddr_in address;
115 	struct sockaddr_in laddr;
116 	socklen_t len = sizeof(laddr);
117 
118 	if (signal(SIGTERM, sig_handler) == SIG_ERR)
119 		error(-1, errno, "signal");
120 
121 	sock = socket(AF_INET, SOCK_STREAM, 0);
122 	if (sock < 0)
123 		error(-1, errno, "socket");
124 
125 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT,
126 				&opt, sizeof(opt)) == -1)
127 		error(-1, errno, "setsockopt");
128 
129 	address.sin_family = AF_INET;
130 	address.sin_addr.s_addr = INADDR_ANY;
131 	/* dynamically allocate unused port */
132 	address.sin_port = 0;
133 
134 	if (bind(sock, (struct sockaddr *)&address, sizeof(address)) < 0)
135 		error(-1, errno, "bind");
136 
137 	if (listen(sock, 3) < 0)
138 		error(-1, errno, "listen");
139 
140 	if (getsockname(sock, (struct sockaddr *)&laddr, &len) == -1)
141 		error(-1, errno, "getsockname");
142 
143 	fprintf(stderr, "server port: %d\n", ntohs(laddr.sin_port));
144 	child_pid = fork();
145 	if (!child_pid)
146 		client(ntohs(laddr.sin_port));
147 	else
148 		server(sock, laddr);
149 
150 	return 0;
151 }
152