[Ubuntu] TCP/IP Socket 통신 서버->클라이언트 메시지 전송 C언어로 구현하기

 

 

 

 

ubuntu@ubuntu8:~/linuxC$ cat hello_server.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>

void error_handling(char *message);

int main(int argc, char *argv[])
{
  int serv_sock;
  int clnt_sock;

  struct sockaddr_in serv_addr;
  struct sockaddr_in clnt_addr;
  socklen_t clnt_addr_size;

  char message[]="Hello World!";

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

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

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

  clnt_addr_size=sizeof(clnt_addr);
  clnt_sock=accept(serv_sock, (struct sockaddr*)&clnt_addr,&clnt_addr_size);
  if(clnt_sock==-1)
        error_handling("accept() error");

  write(clnt_sock, message, sizeof(message));
  sleep(1);
  close(clnt_sock);
  close(serv_sock);
  return 0;
}

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

 

 

ubuntu@ubuntu8:~/linuxC$ cat hello_client.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>

void error_handling(char *message);

int main(int argc, char* argv[])
{
  int sock;
  struct sockaddr_in serv_addr;
  char message[30];
  int str_len;

  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_addr, 0, sizeof(serv_addr));
  serv_addr.sin_family=AF_INET;
  serv_addr.sin_addr.s_addr=inet_addr(argv[1]);
  serv_addr.sin_port=htons(atoi(argv[2]));

  if(connect(sock, (struct sockaddr*)&serv_addr, sizeof(serv_addr))==-1)
        error_handling("connect() error!");

  str_len=read(sock, message, sizeof(message)-1);
  if(str_len==-1)
        error_handling("read() error!");

  printf("Message from server: %s \n", message);
  close(sock);
  return 0;
}

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

 

 

 

컴파일 하고

ubuntu@ubuntu8:~/linuxC$ gcc hello_client.c -o hello_client
ubuntu@ubuntu8:~/linuxC$ gcc hello_server.c -o hello_server

 

 

server를 키고 다른 터미널 열어서 클라이언트를 열면 서버로부터 클라이언트에게 hello world! 가 전송되고 종료된다.

ubuntu@ubuntu8:~/linuxC$ ./hello_server 9999



ubuntu@ubuntu8:~/linuxC$ ./hello_client 127.0.0.1 9999
Message from server: Hello World!