Server program to benchmark so_reuseport

server.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>
#include <netdb.h>

void create_children(int nprocs, int parent_pid)
{
	while (nprocs-- > 0) {
		if (getpid() == parent_pid && fork() < 0)
			exit(1);
	}
}

int main(int argc, char *argv[])
{
	int reuse_port, fd, cfd, nprocs, opt = 1, parent_pid = getpid();
	struct sockaddr_in server;

	if (argc != 4) {
		fprintf(stderr, "Port# #Procs {0->fork, or 1->SO_REUSEPORT}\n");
		return 1;
	}

	nprocs = atoi(argv[2]);
	reuse_port = atoi(argv[3]);
	if (reuse_port)   /* proper SO_REUSEPORT */
		create_children(nprocs, parent_pid);

	if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
		perror("socket");
		return 1;
	}

	if (reuse_port)
		setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, (char *)&opt, sizeof opt);

	server.sin_family      = AF_INET;
	server.sin_addr.s_addr = INADDR_ANY;
	server.sin_port        = htons(atoi(argv[1]));

	if (bind(fd, (struct sockaddr *)&server, sizeof server) < 0) {
		perror("bind");
		return 1;
	}

	if (!reuse_port)   /* simple fork instead of SO_REUSEPORT */
		create_children(nprocs, parent_pid);

	if (parent_pid == getpid()) {
		while (wait(NULL) != -1);   /* wait for all children */
	} else {
		listen(fd, SOMAXCONN);
		while (1) {
			if ((cfd = accept(fd, NULL, NULL)) < 0) {
				perror("accept");
				return 1;
			}
			close(cfd);
		}
	}
	return 0;
}