基于UDP的TFTP简单文本传输协议的下载和上传

tftp 模型以及特点包的格式

 

 代码

#include 
#define PORT 69
#define IP "192.168.0.103"

int do_download(int sfd, struct sockaddr_in sin);
int do_upload(int sfd,struct sockaddr_in sin);

int main(int argc, const char *argv[])
{
    //创建报式套接字    
    int sfd = socket(AF_INET, SOCK_DGRAM, 0);

    if(sfd < 0)
    {
        ERR_MSG("sfd");
        return -1;
    }
    printf("socket create succes sfd=%d __%d__\n", sfd, __LINE__);
 //允许端口快速被复用---监测端口号是否真的有进程在占用，如果没有，则快速复用
    int reuse = 1;
    if(setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) < 0)
    {
        ERR_MSG("setsockopt");
        return -1;
    }
    printf("允许端口快速复用成功\n");

    //定义并填充地址信息结构体，方便发送数据
    //真实的地址信息结构体根据地址族指定　AF_INET :man ip(7)
    struct sockaddr_in sin;
    sin.sin_family      = AF_INET;
    sin.sin_port        = htons(PORT);      //端口号的网络字节序　：　1024-49151
    sin.sin_addr.s_addr = inet_addr(IP);    //本机号的网络字节序列
    char choose = 0;
    while(1)
    {
        printf("-------------------------\n");
        printf("----------1.下载---------\n");
        printf("----------2.上传---------\n");
        printf("----------3.退出---------\n");
        printf("-------------------------\n");
        printf("请输入---->");
        choose = getchar();
        while(getchar()!= '\n');

        switch(choose)
        {
        case '1' :
            //下载
            do_download(sfd, sin);
            break;
        case '2':
            //上传 do_upload
            do_upload(sfd, sin);
            break;
        case '3':
            close(sfd);
            return 0;
            //退出
        default:
            printf("输入错误请重新输出\n");
        }
    }
    //关闭套接字
    if(close(sfd) < 0)
    {
        ERR_MSG("close");
        return -1;
    }
    return 0;
}

int do_download(int sfd, struct sockaddr_in sin)
{

    char cuf[512] = "";
    char brr[200] = "";
    printf("-------->请输入下载的文件\n");
    scanf("%s", brr);

    short *ptr1 = (short *)cuf;
    *ptr1 = htons(1);

    char *ptr2 = cuf + 2;
    strcpy(ptr2, brr);

    char *ptr4 =ptr2+strlen(ptr2)+1;
    strcpy(ptr4,"octet");

    int len = 2+strlen(brr) + 1 + strlen(ptr4) + 1;
    if(sendto(sfd,cuf,len,0,(struct sockaddr*)&sin,sizeof(sin)) < 0 )
    {
        ERR_MSG("sendto");
        return-1;
    }
    //接受返回的地址信息结构体
    struct sockaddr_in cin;
    socklen_t clen = sizeof(cin);

    char buf[516];//数据包
    short * pcr1 = (short *)buf;
    *pcr1 = htons(3);
    short * pcr2 = pcr1 + 1;
    char arr[4];//ack
    short * ptrc1 = (short *)arr;
    *ptrc1 = htons(4);
    short * ptrc2 = ptrc1 + 1;

    ssize_t ter = 0;

    int fp = open("./1.png", O_WRONLY|O_CREAT|O_APPEND|O_TRUNC,0664);
    while(1)
    {
    //接受数据

    ter = recvfrom(sfd,buf,516,0,(struct sockaddr*)&cin,&clen);
    printf("ter=%ld __%d__\n", ter, __LINE__);
    *ptrc2 = *pcr2;
    write(fp,&buf[4], ter-4);

    sendto(sfd,arr,sizeof(arr), 0, (struct sockaddr*)&cin,sizeof(cin));
    if(ter < 516)
    {
    printf("下载成功\n");
        break;
    }

    }
    return 0;
}

int do_upload(int sfd,struct sockaddr_in sin)
{
    int ph = open("./2.png", O_RDONLY);
    char cuf[512] = "";
    char brr[200] = "";
    printf("-------->请输入传输的文件\n");
    scanf("%s", brr);

    short *ptr1 = (short *)cuf;
    *ptr1 = htons(2); //写请求

    char *ptr2 = cuf + 2;
    strcpy(ptr2, brr);

    char *ptr4 =ptr2+strlen(ptr2)+1;
    strcpy(ptr4,"octet");

    int len = 2+strlen(brr) + 1 + strlen(ptr4) + 1;
    if(sendto(sfd,cuf,len,0,(struct sockaddr*)&sin,sizeof(sin)) < 0 )
    {
        ERR_MSG("sendto");
        return-1;
    }
    //打包
    char demo[516] = "";
    short * ctr = (short*) demo;
    *ctr = htons(3);
    short* ctr2 = ctr+1;
    char arr[4];//ack
    short * ptrc1 = (short *)arr;
    *ptrc1 = htons(4);
    short * ptrc2 = ptrc1 + 1;

    ssize_t tev = 0, ter = 0;;                                                                                                  
    int i = 1;
    //定义接收的临时套接字
    struct sockaddr_in cin;
    socklen_t clen = sizeof(cin);

    while(1)
    {
        //发送数据
        if(recvfrom(sfd,arr,sizeof(arr),0,(struct sockaddr*)&cin,&clen)<0)//收到服务器创建的临时套接字地址
        {
           ERR_MSG("recvfrom");
           return -1;
        }
        *ctr2 = htons(i++);//编号
        tev = read(ph,(char*)(demo+4), 512);//读取文件
        if(ter = sendto(sfd, demo,tev+4,0, (struct sockaddr*)&cin, sizeof(cin)) < 0)//发送文件
        {
            ERR_MSG("sendto");
            return -1;
        }
        if(tev < 512)
        {
            printf("发送成功\n");
            break;
        }

        printf("ter = %ld __%d__\n", ter, __LINE__);
    }
    return 0;
}

 现象

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