TCP 기반 에코 클라이언트와 Iterative 에코 서버를 구현하는 프로그램

echo(메아리)

echo_server

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

#define BUF_SIZE 1024
#define MAX_CLIENTS 6
void error_handling(char *message);

int main(int argc, char *argv[])
{
    int serv_sock, clnt_sock;
    char message[BUF_SIZE];
    int str_len;
    struct sockaddr_in serv_adr, clnt_adr;
    socklen_t clnt_adr_sz;

    if (argc != 2) {
        printf("Usage: %s <port>\n", argv[0]);
        exit(1);
    }

    serv_sock = socket(PF_INET, SOCK_STREAM, 0);
    if (serv_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 = htonl(INADDR_ANY);
    serv_adr.sin_port = htons(atoi(argv[1]));

    if (bind(serv_sock, (struct sockaddr*)&serv_adr, sizeof(serv_adr)) == -1)
        error_handling("bind() error");

    if (listen(serv_sock, 5) == -1)
        error_handling("listen() error");

    clnt_adr_sz = sizeof(clnt_adr);

    for (int i = 0; i < MAX_CLIENTS; i++) {
        clnt_sock = accept(serv_sock, (struct sockaddr*)&clnt_adr, &clnt_adr_sz);
        if (clnt_sock == -1)
            error_handling("accept() error");
        else
            printf("Connected client %d\n", i + 1);

        // 클라이언트로부터 메시지 수신 및 에코
        while ((str_len = read(clnt_sock, message, BUF_SIZE)) != 0)
            write(clnt_sock, message, str_len);

        close(clnt_sock);
    }

    close(serv_sock);
    return 0;
}

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

 

echo_client

#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;
    struct sockaddr_in serv_adr;

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

    sock = socket(PF_INET, SOCK_STREAM, 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]));

    if (connect(sock, (struct sockaddr*)&serv_adr, sizeof(serv_adr)) == -1)
        error_handling("connect() error!");
    else
        puts("Connected...........");

    // 고정된 메시지 전송
    strcpy(message, "Named Data Networking(NDN) is a promising design of Information Centric Networking(ICN) for realizing future Internet architecture. NDN uses globally unique and hierarchical names for data fetching. NDN changes the communication paradigm from the data location to the name of the data.");

    // 서버로 메시지 전송
    write(sock, message, strlen(message));

    // 서버로부터 에코 메시지 수신
    str_len = read(sock, message, BUF_SIZE - 1);
    message[str_len] = 0; // 문자열 끝 추가
    printf("Message from server: %s\n", message);

    close(sock);
    return 0;
}

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