server.c

#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include <netinet/in.h>
 
#define CLIENT_QUEUE_LEN 10
#define SERVER_PORT 7002
 
int main(void)
{
	int listen_sock_fd = -1, client_sock_fd = -1;
	struct sockaddr_in6 server_addr, client_addr;
	socklen_t client_addr_len;
	char str_addr[INET6_ADDRSTRLEN];
	int ret, flag;
	char ch;
 
	/* Create socket for listening (client requests) */
	listen_sock_fd = socket(AF_INET6, SOCK_STREAM, IPPROTO_TCP);
	if(listen_sock_fd == -1) {
		perror("socket()");
		return EXIT_FAILURE;
	}
 
	/* Set socket to reuse address */
	flag = 1;
	ret = setsockopt(listen_sock_fd, SOL_SOCKET, SO_REUSEADDR, &flag, sizeof(flag));
	if(ret == -1) {
		perror("setsockopt()");
		return EXIT_FAILURE;
	}

	server_addr.sin6_family = AF_INET6;
	server_addr.sin6_addr = in6addr_any;
	server_addr.sin6_port = htons(SERVER_PORT);
 
	/* Bind address and socket together */
	ret = bind(listen_sock_fd, (struct sockaddr*)&server_addr, sizeof(server_addr));
	if(ret == -1) {
		perror("bind()");
		close(listen_sock_fd);
		return EXIT_FAILURE;
	}
 
	/* Create listening queue (client requests) */
	ret = listen(listen_sock_fd, CLIENT_QUEUE_LEN);
	if (ret == -1) {
		perror("listen()");
		close(listen_sock_fd);
		return EXIT_FAILURE;
	}
 
	client_addr_len = sizeof(client_addr);
 
	while(1) {
		/* Do TCP handshake with client */
		client_sock_fd = accept(listen_sock_fd,
				(struct sockaddr*)&client_addr,
				&client_addr_len);
		if (client_sock_fd == -1) {
			perror("accept()");
			close(listen_sock_fd);
			return EXIT_FAILURE;
		}
 
		inet_ntop(AF_INET6, &(client_addr.sin6_addr),
				str_addr, sizeof(str_addr));
		printf("New connection from: %s:%d ...\n",
				str_addr,
				ntohs(client_addr.sin6_port));
 
		/* Wait for data from client */
		ret = read(client_sock_fd, &ch, 1);
		if (ret == -1) {
			perror("read()");
			close(client_sock_fd);
			continue;
		}
 
		/* Do very useful thing with received data :-) */
		ch++;
 
		/* Send response to client */
		ret = write(client_sock_fd, &ch, 1);
		if (ret == -1) {
			perror("write()");
			close(client_sock_fd);
			continue;
		}
 
		/* Do TCP teardown */
		ret = close(client_sock_fd);
		if (ret == -1) {
			perror("close()");
			client_sock_fd = -1;
		}
 
		printf("Connection closed\n");
	}
	return EXIT_SUCCESS;
}