Chapter 5 (echo_client2)

<echo_client2.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

void error_handling(char *message);

int main(int argc, char *argv[])
{
	int sock;
	char message[BUF_SIZE];
	int str_len, recv_len, recv_cnt;
	struct sockaddr_in serv_adr;

	if (argc != 3) {
		printf("Usage : %s <IP> <port>\n", argv[0]);
		exit(1);
	}
	
	// 소켓 생성
	sock = socket(PF_INET, SOCK_STREAM, 0);   
	if (sock == -1)
		error_handling("socket() error");
	
	// 서버 주소 설정
	memset(&serv_adr, 0, sizeof(serv_adr));
	serv_adr.sin_family = AF_INET;
	serv_adr.sin_addr.s_addr = inet_addr(argv[1]);
	serv_adr.sin_port = htons(atoi(argv[2]));
	
	// 서버에 연결
	if (connect(sock, (struct sockaddr*)&serv_adr, sizeof(serv_adr)) == -1)
		error_handling("connect() error!");
	else
		puts("Connected...........");
	
	while (1) 
	{
		fputs("Input message (Q to quit): ", stdout);
		fgets(message, BUF_SIZE, stdin);
		
		if (!strcmp(message, "q\n") || !strcmp(message, "Q\n"))
			break;

		// 메시지 서버로 전송
		str_len = write(sock, message, strlen(message));
		
		recv_len = 0;
		while (recv_len < str_len)
		{
			// 서버로부터 데이터를 받음
			recv_cnt = read(sock, &message[recv_len], BUF_SIZE - 1);
			if (recv_cnt == -1)
				error_handling("read() error!");
			recv_len += recv_cnt;
		}
		
		message[recv_len] = 0;
		printf("Message from server: %s", message);
	}
	
	close(sock);
	return 0;
}

// 에러 핸들링 함수
void error_handling(char *message)
{
	fputs(message, stderr);
	fputc('\n', stderr);
	exit(1);
}