#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h> 
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <getopt.h>
#include <ctype.h>

void print_usage(char *progname)
{
	printf("%s usage: \n", progname);
	printf("-p(--port): sepcify server listen port.\n");
	printf("-h(--Help): print this help information.\n");

	return ;
}

int main(int argc, char **argv)
{
	int                  sockfd = -1;
	int                  rv = -1;
	struct sockaddr_in   servaddr;
	struct sockaddr_in   cliaddr;
	socklen_t            len;
	int                  port = 0;
	int                  clifd;
	int                  ch;
	int                  on = 1;
	pid_t                pid;

       	struct option        opts[] = {
		{"port", required_argument, NULL, 'p'},
		{"help", no_argument, NULL, 'h'},
		{NULL, 0, NULL, 0}
	};

	while( (ch=getopt_long(argc, argv, "p:h", opts, NULL)) != -1 ) 
	{
		switch(ch)
		{
			case 'p':
				port=atoi(optarg);
				break;

			case 'h':
				print_usage(argv[0]);
				return 0;
		}

	}

	if( !port )
	{
		print_usage(argv[0]);
		return 0;
	}

	sockfd=socket(AF_INET, SOCK_STREAM, 0);
	if(sockfd < 0)
	{
		printf("Create socket failure: %s\n", strerror(errno));
		return -1;
	}
	printf("Create socket[%d] successfully!\n", sockfd);

	setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));

	memset(&servaddr, 0, sizeof(servaddr));
	servaddr.sin_family=AF_INET;
	servaddr.sin_port = htons(port);
	servaddr.sin_addr.s_addr = htonl(INADDR_ANY); /* listen all the IP address on this host */
	//inet_aton("192.168.0.16", &servaddr.sin_addr); /* Only listen specify IP address on this host */

	rv=bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
	if(rv < 0)
	{
		printf("Socket[%d] bind on port[%d] failure: %s\n", sockfd, port, strerror(errno));
		return -2;
	}

	listen(sockfd, 13);
	printf("Start to listen on port [%d]\n", port);

	while(1)
	{ 
		printf("Start accept new client incoming...\n");

		clifd=accept(sockfd, (struct sockaddr *)&cliaddr, &len);
		if(clifd < 0)
		{
			printf("Accept new client failure: %s\n", strerror(errno));
			continue;
		}

		printf("Accept new client[%s:%d] successfully\n", inet_ntoa(cliaddr.sin_addr), ntohs(cliaddr.sin_port));

		pid = fork();
		if( pid < 0 )
		{
			printf("fork() create child process failure: %s\n", strerror(errno));
			close(clifd);
			continue;
		}
		else if( pid > 0 ) 
		{
			/* Parent process close client fd and goes to  accept new socket client again */
			close(clifd);
			continue;
		}
		else if ( 0 == pid )
		{ 
			char                 buf[1024];
			int                  i;

			printf("Child process start to commuicate with socket client...\n");

			close(sockfd); /* Child process close the listen socket fd */

			while(1)
			{
			       	memset(buf, 0, sizeof(buf));
			       	rv=read(clifd, buf, sizeof(buf));
			       	if( rv < 0 )
			       	{
				       	printf("Read data from client sockfd[%d] failure: %s\n", clifd, strerror(errno));
				       	close(clifd);
				       	exit(0);
			       	}
			       	else if( rv == 0)
			       	{ 
					printf("Socket[%d] get disconnected\n", clifd);
				       	close(clifd);
				       	exit(0);
			       	} 
				else if( rv > 0 ) 
				{
				       	printf("Read %d bytes data from Server: %s\n", rv, buf);
			       	} 

				/* convert letter from lowercase to uppercase */
				for(i=0; i<rv; i++)
				{
				       	buf[i]=toupper(buf[i]);
				}

				rv=write(clifd, buf, rv);
			       	if(rv < 0)
			       	{
				       	printf("Write to client by sockfd[%d] failure: %s\n", clifd, strerror(errno));
				       	close(clifd);
				       	exit(0);
			       	}

			} /* Child process loop */

		} /* Child process start*/
	}


	close(sockfd);

	return 0;
}