server.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#define BUF_SIZE 1024

int main(int argc, char * argv[]){
	int serv_sock,clnt_sock;
	FILE *readfp;
	FILE *writefp;
	struct sockaddr_in serv_adr,clnt_adr;
	socklen_t clnt_adr_sz;
	char buf[BUF_SIZE];

	serv_sock = socket(PF_INET,SOCK_STREAM,0);

	memset(&serv_adr,0,sizeof(serv_adr));
	serv_adr.sin_family = AF_INET;
	serv_adr.sin_addr.s_addr = htonl(INADDR_ANY);
	serv_adr.sin_port = htons(atoi(argv[1]));

	bind(serv_sock,(struct sockaddr *)&serv_adr,sizeof(serv_adr));

	listen(serv_sock,5);

	clnt_adr_sz = sizeof(clnt_adr);

	clnt_sock = accept(serv_sock,(struct sockaddr *)&clnt_adr,&clnt_adr_sz);

	readfp = fdopen(clnt_sock,"r");
	writefp = fdopen(dup(clnt_sock),"w");

	fputs("from server: Hi~ client? \n",writefp);
	fputs("I love all the world! \n",writefp);
	fflush(writefp);

	shutdown(fileno(writefp),SHUT_WR);

	fclose(writefp);
	fgets(buf,sizeof(buf),readfp);
	fputs(buf,stdout);

	fclose(readfp);

	return 0;
}