[Linux, C] echo connect client UDP통신

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

#define BUF_SIZE 30

void error_handling(char *message);

int main(int argc, char *argv[]){
        int sock;
        char message[BUF_SIZE];
        int str_len;
        socklen_t adr_sz;

        struct sockaddr_in serv_adr, form_adr;

        if(argc!=3){
                printf("Usage:%s <IP> <port> \n", argv[0]);
                exit(1);
        }

        sock = socket(PF_INET, SOCK_DGRAM, 0);
        if(sock == -1)
                error_handling("socket() error");

        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]));

        connect(sock, (struct sockaddr*)&serv_adr, sizeof(serv_adr));

        while(1){
                fputs("Insert message(q to quit):", stdout);
                fgets(message, sizeof(message), stdin);
                if(!strcmp(message,"q\n") || !strcmp(message, "Q\n"))
                        break;

                /*
                 * sendto(sock, message, strlen(message), 0, (struct sockaddr*)&serv_adr, sizeof(serv_adr));
                 */

                write(sock, message, strlen(message));

                /*
                 * adr_sz = sizeof(from_adr);
                 * str_len = recvfrom(sock,message, BUF_SIZE, 0, (struct sockaddr*)&from_adr, &adr_sz);
                 */

                str_len = read(sock,message, sizeof(message)-1);
                message[str_len] = 0;
                printf("Message from server: %s", message);
        }
        close(sock);
        return 0;
}

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