UDP 는 뭐지?

그냥 보내니깐 열라 빠름

하지만 데이타의 손실이 치명적이면 안쓰는게 좋음

 

#include <sys/socket.h>

ssuze_t sendto(int sock, void *buff, size_t nbytes, int flags,struct sockaddr *to, socklen_t addrlen);

 

sockaddr *to 이게 중요함 보내는곳이 있움

 

#include <sys/socket.h>

ssize_t recvfrom(int sock, void *buff, size_t nbytes, int flags, struct sockaddr *from, socklen_t *addrlen);

 

데이터 송수신을 확인함

 

 

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

#define BUF_SIZE 30
viod error_handling(char *message);

int main(int argc, char *argv[])
{
	int serv_sock;
    char message[BUF_SIZE];
    int str_len;
    socklen_t clnt_adr_sz;
    
    struct sockaddr_in serv_adr, clnt_adr;
    if(argc!=2)
    {
    	printf("Usage : %s <port>\n", argv[0]);
        exit(1);
    }
    
    serv_sock=socket(PF_INET, SOCK_DGRAM, 0);
    if(serv_sock == -1)
    	error_handling("UDP socket creation 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");
    
    while(1)
    {
    	clnt_adr_sz=sizeof(clnt_adr);
        str_len=recvfrom(serv_sock, message, BUF_SIZE, 0, 
        	(struct sockaddr*)&clnt_adr, &clnt_adr_sz);
        sendto(serv_sock, message, str_len, 0,
        	(struct sockaddr*)&clnt_adr, clnt_adr_sz);
    }
    close(serv_sock);
    return 0;
}

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

음

신기한거같음 상관업이 보네도되는건가?

 

클라이언트 엔받는애인거 같은데

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

#define BUF_SIZE 30
viod 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, from_adr;
    if(argc!=3)
    {
    	printf("Usage : %s <IP> <port>\n", argv[0]);
        exit(1);
    }
    
    sock=socket(PF_INET, SOCK_DGRAM, 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=inet_addr(argv[1]);
    serv_adr.sin_port=htons(atoi(argv[2]));
 
    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));
        adr_sz=sizeof(from_adr);
        str_len=recvfrom(sock, message, BUF_SIZE, 0,
        	(struct sockaddr*)&from_adr, &adr_sz);
        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(i); 
}

잘 받은듯 하다