1. 基于UDP的TFTP文件传输

#include "test.h"

#define SER_IP "192.168.1.104"
#define SER_PORT 69
#define IP "192.168.191.128"
#define PORT 9999

enum mode
{
    TFTP_READ = 1,
    TFTP_WRITE = 2,
    TFTP_DATA = 3,
    TFTP_ACK = 4,
    TFTP_ERR = 5
};

void get_filename(char* filename, int size)
{
    bzero(filename, size);

    printf("请输入文件名：");
    fgets(filename, size, stdin);
    filename[strlen(filename) - 1] = 0;
}

void rw_request(char* pack, int pack_size, char* filename, int mode, int* packlen)
{
    bzero(pack, pack_size); 

    short* p1 = (short*)pack;
    *p1 = htons(mode);

    char* p2 = (char*)(p1 + 1);
    strcpy(p2, filename);

    char* p4 = p2 + strlen(p2) + 1;
    strcpy(p4, "octet");

    *packlen = 4 + strlen(p2) + strlen(p4);
}

void pack_data(char* pack, int num, char* rbuf, int len, int* packlen)
{
    bzero(pack, sizeof(pack)); 

    short* p1 = (short*)pack;
    *p1 = htons(TFTP_DATA);

    short* p2 = p1 + 1;
    *p2 = htons(num);

    char* p4 = (char*)(p2 + 1);
    for (int i = 0; i < len; i++)
    {
        *(p4 + i) = rbuf[i];
    }

    *packlen = 4 + len;
}

void pack_ack(char* ack, int num)
{
    bzero(ack, 4);

    short* a = (short*)ack;
    *a = htons(TFTP_ACK);
    *(a + 1) = htons(num);
}

void pack_errmsg(char* pack, char* msg, int* packlen)
{
    bzero(pack, sizeof(pack));

    short* p = (short*)pack;
    *p = htons(TFTP_ERR);
    *(p + 1) = htons(0);

    char* errmsg = (char*)(p + 2);
    strcpy(errmsg, msg);

    *packlen = 4 + strlen(errmsg);
}

void client_recv(int sfd, struct sockaddr_in* sin, socklen_t* socklen)
{
    char filename[128];
    get_filename(filename, sizeof(filename));

    char pack[516] = "";
    int packlen = 0;
    rw_request(pack, sizeof(pack), filename, TFTP_READ, &packlen);
    
    sendto(sfd, pack, packlen, 0, (struct sockaddr*)sin, *socklen);

    int fd = -1;
    if ((fd = open(filename, O_WRONLY|O_CREAT|O_TRUNC, 0664)) == -1)
    {
        perror("create file error");
        return;
    }

    char wbuf[512] = "";
    int block_num = 0;
    while (1)
    {
        bzero(pack, sizeof(pack));
        packlen = recvfrom(sfd, pack, sizeof(pack), 0, (struct sockaddr*)sin, socklen);
        short* p = (short*)pack;
        short code = ntohs(*p);
        short num = ntohs(*(p + 1));

        if (3 == code && num == ++block_num)
        {
            write(fd, pack + 4, packlen - 4);

            char ack[4];
            pack_ack(ack, block_num);
            sendto(sfd, ack, 4, 0, (struct sockaddr*)sin, *socklen);
            
            if (packlen < 512)
            {
                printf("下载完成\n");
                close(fd);
                break;
            }
        }
    }
}

void client_send(int sfd, struct sockaddr_in* sin, socklen_t* socklen)
{
    char filename[128];
    get_filename(filename, sizeof(filename));

    char pack[516] = "";
    int packlen = 0;
    rw_request(pack, sizeof(pack), filename, TFTP_WRITE, &packlen);

    sendto(sfd, pack, packlen, 0, (struct sockaddr*)sin, *socklen);

    int fd = -1;
    if ((fd = open(filename, O_RDONLY)) == -1)
    {
        perror("open error");
        return;
    }

    char ack[4];
    char rbuf[512] = "";
    int len;
    while (1)
    {
        recvfrom(sfd, ack, 4, 0, (struct sockaddr*)sin, socklen);
        short* a = (short*)ack;
        short code = ntohs(*a);
        short num = ntohs(*(a + 1));

        if (4 == code && (len = read(fd, rbuf, sizeof(rbuf))) > 0)
        {
            pack_data(pack, num + 1, rbuf, len, &packlen);

            sendto(sfd, pack, packlen, 0, (struct sockaddr*)sin, *socklen);

            bzero(rbuf, sizeof(rbuf));

        }
        else
        {
            printf("上传成功\n");
            break;
        }
    }
}

int main(int argc, char const *argv[])
{
    int sfd = -1;
    sfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (-1 == sfd)
    {
        perror("socket error");
        return -1;
    }
    printf("sfd = %d\n", sfd);

    int reuse = 1;
    if (setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) == -1)
    {
        perror("setsockopt error");
        return -1;
    }
    printf("端口号快速重用成功\n");

    struct sockaddr_in sin;
    sin.sin_family = AF_INET;
    sin.sin_port = htons(SER_PORT);
    sin.sin_addr.s_addr = inet_addr(SER_IP);
    socklen_t socklen = sizeof(sin);

    printf("1.上传\n");
    printf("2.下载\n");
    printf("0.退出\n");
    printf("请输入：");
    int n;
    scanf("%d", &n);
    getchar();

    if (1 == n)
    {
        client_send(sfd, &sin, &socklen);
    }
    else if (2 == n)
    {
        client_recv(sfd, &sin, &socklen);
    }
    else
    {
        printf("输入错误\n");
    }
    
    close(sfd);

    return 0;
}

2. TCP机械臂测试