单进程架构

accept.c

#include <stdio.h>
#include <sys/socket.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

int child(int, int);

int 
main() {
	int fd;
	struct sockaddr_in addr;
	int succ;
	int i;

	fd = socket(AF_INET, SOCK_STREAM, 0);
	if (fd == -1) {
		perror("socket");
		goto err_out;
	}

	memset(&addr, 0, sizeof(addr));
	addr.sin_family = AF_INET;
	addr.sin_addr.s_addr = INADDR_ANY;
	addr.sin_port = htons(9997);
	
	succ = bind(fd, (struct sockaddr*)&addr, sizeof(addr));
	if (succ != 0) {
		perror("bind");
		goto closesock;
	}

	succ = listen(fd, 5);
	if (succ != 0) {
		perror("listen");
		goto closesock;
	}
	
	for (i=0; i<5; i++) {
		succ = fork();
		if (succ < 0) {
			perror("fork");
			goto closesock;
		} else if (succ == 0) {
			// parent process
			continue;
		} else {
			// child process
			return child(i, fd);
		}
	}

	return 0;

closesock:
	close(fd);
err_out:
	return -1;
}

int 
child(int idx, int serverfd) {
	int fd;
	struct sockaddr_in addr;
	socklen_t len;
	char addrName[INET_ADDRSTRLEN];
	const char *addrP;
	char buf[] = "hello";

	while(1) {
		len = sizeof(addr);
		fd = accept(serverfd, (struct sockaddr*)&addr, &len);
		if (fd < 0) {
			perror("accept");
			return -1;
		} 
	
		addrP = inet_ntop(AF_INET, &addr, (char*)addrName, len);
		printf("%d accept a connect: %s\n", idx, addrP);
		write(fd, buf, strlen(buf));	
		close(fd);
	}

	return 0;
}