tcp_local.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/un.h>
#include <sys/types.h> 
#include <sys/socket.h>

static void print_usage(char *progname)
{
    printf("usage : %s [server|client]\n", progname);
}

static int do_server(void)
{
    /*
        socket
        bind
        listen
        accept
        write/read
   */
    
    int ret, sockfd, clifd;
    struct sockaddr_un servaddr;
    char buf[128];

    /*
        Address format
        A UNIX domain socket address is represented in the following structure:

        struct sockaddr_un {
            sa_family_t sun_family;              
            char        sun_path[108];            
        };
   */
    
    sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
    if(sockfd < 0) {
        perror("socket");
        return -1;
    }
    
    memset(&servaddr, 0, sizeof(servaddr));
    servaddr.sun_family = AF_UNIX;
    strcpy(servaddr.sun_path, "./sockpath");
    
    ret = bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
    if(ret < 0) {
        perror("bind");
        close(sockfd);
        return -1;
    }

    ret = listen(sockfd, 8);
    if(ret < 0) {
        perror("listen");
        close(sockfd);
        return -1;
    }  
    
    // socket IPC에서는 클라이언트 정보를 받아올 필요는 없다
    clifd = accept(sockfd, NULL, NULL);
    if(clifd < 0) {
        perror("accept");
        close(sockfd);
        return -1;
    }

    memset(buf, 0, sizeof(buf));
    // recv는 clifd를 socket fd로 전
    recv(clifd, buf, sizeof(buf), 0);
    printf("Received data : %s\n", buf);

    close(sockfd);
    close(clifd);
    return 0; 
}

static int do_client(void)
{
    int sockfd, ret;
    struct sockaddr_un cliaddr;
    char buf[128];

    sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
    if(sockfd < 0) {
        perror("socket");
        return -1;
    }

    memset(&cliaddr, 0, sizeof(cliaddr));
    cliaddr.sun_family = AF_UNIX;
    strcpy(cliaddr.sun_path, "./sockpath");
    
    ret = connect(sockfd, (struct sockaddr *)&cliaddr, sizeof(cliaddr));
    if(ret < 0) {
        perror("connect");
        close(sockfd);
        return -1;
    }

    memset(buf, 0, sizeof(buf));
    snprintf(buf, sizeof(buf), "This is msg from sock_stream");

    ret = send(sockfd, buf, sizeof(buf), 0);
    if(ret < 0) {
        perror("send");
        close(sockfd);
        return -1;
    }

    close(sockfd);
    return 0;
}

int main(int argc, char **argv) 
{
    int ret;

    if(argc < 2) {
        print_usage(argv[0]);
        return -1;
    }

    if(!strcmp(argv[1], "server")) {
        ret = do_server();
    } else if(!strcmp(argv[1], "client")) {
        ret = do_client();
    } else {
        print_usage(argv[0]);    
    } 

    return 0;
}