linux udp封装函数

create_UDP_socket(char *ip, int port, int type)
{
    struct sockaddr_in  addr;
    int sockfd;
    int on_off = 1;
    addr.sin_family = AF_INET;
    if (ip == NULL) {
        addr.sin_addr.s_addr = htonl(INADDR_ANY);
    }
    else {
        addr.sin_addr.s_addr = inet_addr(ip);
    }

    addr.sin_port = htons(port);
    if ((sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1) {
        return(-1);
    }

    fcntl(sockfd, F_SETFD, FD_CLOEXEC);

    if(type == 0) {//listener
        setsockopt(sockfd,SOL_SOCKET, SO_REUSEADDR, (const void *)&on_off, sizeof(on_off));
        if (bind(sockfd, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
            close(sockfd);
            return(-1);
        }
    }
    else {//sender
        if(connect(sockfd, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
            close(sockfd);
            return(-1);
       }
   }
    return(sockfd);
}