IO网络4.0

思维导图

tftp上传

#include 

#define ERR_LOG(msg) do{\
    perror(msg);\
    printf("%d %s %s\n", __LINE__, __func__, __FILE__);\
}while(0)

#define PORT   	 69 
#define N         516

int do_upload(int sfd, struct sockaddr_in sin);

int main(int argc, const char *argv[])
{
    if(argc < 2)
    {
        printf("请输入IP\n");
        return -1;
    }
    //1.创建报式套接字
    int sfd = socket(AF_INET, SOCK_DGRAM, 0);
    if(sfd < 0)
    {
        perror("socket");
        return -1;
    }

    //2.填充服务器ip和端口号
    struct sockaddr_in sin;
    sin.sin_family = AF_INET;
    sin.sin_port = htons(PORT);
    sin.sin_addr.s_addr = inet_addr(argv[1]);

    char choose;
    while(1)
    {
        printf("######1.上传######\n");
        printf("######2.退出######\n");

        scanf("%c", &choose);
        while(getchar()!=10);

        switch(choose)
        {
        case '1':
            //上传功能,todo
            do_upload(sfd, sin);
            break;
        case '2':
            goto END;
            break;
        default:
            printf("输入错误\n");
        }
        printf("请输入任意字符清屏:");
        while(getchar()!=10);        
    }
    
    //关闭文件描述符
END:
    close(sfd);
    return 0;
}

//上传功能
int do_upload(int sfd, struct sockaddr_in sin)
{
    char filename[20] = "";
    printf("请输入要上传的文件名:");
    fgets(filename, 20, stdin);
    filename[strlen(filename)-1] = 0;

    //判断该文件是否存在
    int fd = open(filename, O_RDONLY);
    if(fd < 0)
    {
        if(errno == ENOENT)
        {
            printf(">>>文件不存在,请重新输入<<<\n");
            return -2;
        }
        else
        {
            ERR_LOG("open");
            return -1;
        }
    }
    
    //发送上传请求
    //上传协议
    char buf[N] = "";
    int size = sprintf(buf, "%c%c%s%c%s%c", 0, 2, filename, 0, "octet", 0);

    if(sendto(sfd, buf, size, 0, (struct sockaddr*)&sin, sizeof(sin))<0)
    {
        ERR_LOG("sendto");
        return -1;
    }

    //循环接收发送数据包
    int recv_len;
    unsigned short num = 0;
    socklen_t addrlen = sizeof(sin);
    while(1)
    {
        bzero(buf, N);
        recv_len = recvfrom(sfd, buf, sizeof(buf), 0, (struct sockaddr*)&sin, &addrlen);
        if(recv_len < 0)
        {
            ERR_LOG("recvfrom");
            return -1;
        }

        //操作码的范围是1-5,因为是网络字节序
        //所以有效操作吗存储在高位,即buf[1]的位置.
		//服务器返回应答包
        if(4 == buf[1])
        {
            //判断当前数据包的编号是否等于应答包的编号
            //防止数据包在传送过程丢包或重复收包
            if(num == ntohs(*(unsigned short*)(buf+2)))
            {
                //修改操作码为数据包
                buf[1] = 3;

                //填充块编号
                num++;
                *(unsigned short*)(buf+2) = htons(num);

                //读取数据
                //发送数据
                int res = read(fd, buf+4, N-4);
                if(res < 0)
                {
                    ERR_LOG("read");
                    return -1;
                }
                else if(0 == res)
                {
                    printf("-----文件上传完毕-----\n");
                    break;
                }

                //发送数据包
                //发送的数据包大小为,读取到的字节数(res)+操作码(2byte)+快编号(2byte)
                if(sendto(sfd, buf, res+4, 0, (struct sockaddr*)&sin, sizeof(sin)) <0)
                {
                    ERR_LOG("sendto");
                    return -1;
                }
            }
            else
            {
                printf("-----文件上传失败,请检查网络环境-----\n");
                break;
            }
        }
        else if(5 == buf[1])
        {
            printf("-----ERROR:%s-----\n", buf+4);
            break;
        }

    }
    return 0;
}