// tftp_client.c : 定义控制台应用程序的入口点。 #include"udp_tftp.h" u_short RRQ_OP = 0x0100; u_short WRQ_OP = 0x0200; u_short DATA_OP = 0x0300; u_short ACK_OP = 0x0400; u_short ERROR_OP = 0x0500; /*上传文件，WRQ*/ int client_upload_file(char*inputfilename,int server_port ,char *server_ip) { … close(clientSocket); return 1; }

这段代码是一个 TFTP（Trivial File Transfer Protocol，简单文件传输协议）客户端的实现，主要实现了上传文件的功能。其中定义了一些操作码，包括 RRQ（读请求）、WRQ（写请求）、DATA（数据传输）、ACK（确认）和 ERROR（错误）。函数 `client_upload_file` 接收三个参数，分别为需要上传的文件名、服务器端口号和服务器 IP 地址。具体实现细节需要看函数内部的代码。

相关问题

在FreeRTOS中使用任务来实现并发处理。例如，定义一个任务来处理TFTP请求： 完整案例代码

以下是一个使用FreeRTOS和lwIP实现的并发处理的TFTP服务器的完整案例代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>

#include "lwip/sockets.h"
#include "lwip/sys.h"
#include "lwip/netdb.h"

#include "FreeRTOS.h"
#include "task.h"
#include "semphr.h"
#include "queue.h"

#define TFTP_OPCODE_RRQ 1
#define TFTP_OPCODE_DATA 3
#define TFTP_OPCODE_ACK 4
#define TFTP_OPCODE_ERROR 5

#define TFTP_ERROR_FILE_NOT_FOUND 1
#define TFTP_ERROR_ACCESS_VIOLATION 2
#define TFTP_ERROR_DISK_FULL 3
#define TFTP_ERROR_ILLEGAL_OPERATION 4
#define TFTP_ERROR_UNKNOWN_TRANSFER_ID 5
#define TFTP_ERROR_FILE_EXISTS 6
#define TFTP_ERROR_NO_SUCH_USER 7

#define MAX_FILENAME_LEN 128
#define MAX_DATA_LEN 512

static SemaphoreHandle_t file_mutex;
static QueueHandle_t file_data_queue;

static int read_file(const char *filename, unsigned char *buf, int buflen)
{
    int fd = open(filename, O_RDONLY);
    if (fd < 0) {
        return -1;
    }

    int ret = read(fd, buf, buflen);
    close(fd);

    return ret;
}

static int write_file(const char *filename, unsigned char *buf, int buflen)
{
    int fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
    if (fd < 0) {
        return -1;
    }

    int ret = write(fd, buf, buflen);
    close(fd);

    return ret;
}

static void tftp_task(void *pvParameters)
{
    int sockfd = *(int *)pvParameters;
    struct sockaddr_in client_addr;
    unsigned char buf[1024];

    while (1) {
        // receive request from client
        int len = sizeof(struct sockaddr_in);
        int ret = recvfrom(sockfd, buf, sizeof(buf), 0, (struct sockaddr *)&client_addr, &len);
        if (ret < 0) {
            // error handling
        }

        // process request
        unsigned short opcode = ntohs(*(unsigned short *)buf);
        char *filename = (char *)&buf[2];
        char *mode = filename + strlen(filename) + 1;

        switch (opcode) {
            case TFTP_OPCODE_RRQ:
            {
                xSemaphoreTake(file_mutex, portMAX_DELAY);
                int data_len = read_file(filename, buf, sizeof(buf));
                xSemaphoreGive(file_mutex);

                if (data_len < 0) {
                    buf[1] = TFTP_OPCODE_ERROR;
                    buf[3] = TFTP_ERROR_FILE_NOT_FOUND;
                    sendto(sockfd, buf, 4, 0, (struct sockaddr *)&client_addr, sizeof(struct sockaddr_in));
                } else {
                    int block_num = 1;
                    int data_sent = 0;

                    while (data_sent < data_len) {
                        buf[0] = 0;
                        buf[1] = TFTP_OPCODE_DATA;
                        *(unsigned short *)&buf[2] = htons(block_num);
                        memcpy(&buf[4], &buf[data_sent], MAX_DATA_LEN);

                        int data_to_send = data_len - data_sent;
                        if (data_to_send > MAX_DATA_LEN) {
                            data_to_send = MAX_DATA_LEN;
                        }

                        sendto(sockfd, buf, data_to_send + 4, 0, (struct sockaddr *)&client_addr, sizeof(struct sockaddr_in));

                        int ack_len = recvfrom(sockfd, buf, sizeof(buf), 0, (struct sockaddr *)&client_addr, &len);
                        if (ack_len < 0) {
                            // error handling
                        }

                        if (ntohs(*(unsigned short *)buf) == TFTP_OPCODE_ACK && ntohs(*(unsigned short *)&buf[2]) == block_num) {
                            data_sent += MAX_DATA_LEN;
                            block_num++;
                        }
                    }
                }

                break;
            }

            case TFTP_OPCODE_DATA:
            {
                unsigned short block_num = ntohs(*(unsigned short *)&buf[2]);
                xQueueSend(file_data_queue, &buf[4], 0);

                buf[0] = 0;
                buf[1] = TFTP_OPCODE_ACK;
                *(unsigned short *)&buf[2] = htons(block_num);
                sendto(sockfd, buf, 4, 0, (struct sockaddr *)&client_addr, sizeof(struct sockaddr_in));

                break;
            }

            case TFTP_OPCODE_ERROR:
            {
                // error handling
                break;
            }

            default:
            {
                buf[0] = 0;
                buf[1] = TFTP_OPCODE_ERROR;
                buf[3] = TFTP_ERROR_ILLEGAL_OPERATION;
                sendto(sockfd, buf, 4, 0, (struct sockaddr *)&client_addr, sizeof(struct sockaddr_in));
                break;
            }
        }
    }
}

int main(int argc, char **argv)
{
    file_mutex = xSemaphoreCreateMutex();
    file_data_queue = xQueueCreate(10, MAX_DATA_LEN);

    struct sockaddr_in server_addr;
    int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sockfd < 0) {
        // error handling
    }

    memset(&server_addr, 0, sizeof(struct sockaddr_in));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    server_addr.sin_port = htons(69);

    if (bind(sockfd, (struct sockaddr *)&server_addr, sizeof(struct sockaddr_in)) < 0) {
        // error handling
    }

    xTaskCreate(tftp_task, "tftp_task", 2048, &sockfd, tskIDLE_PRIORITY + 1, NULL);

    vTaskStartScheduler();
}

此代码实现了一个简单的TFTP服务器，可以处理客户端的读取文件请求和数据传输请求。文件的读写操作使用了互斥量来保证一致性，数据的传输使用了消息队列来传递。

使用C语言实现tftp协议的客户端和服务端，并明确定义出操作码

TFTP是一个基于UDP协议的简单文件传输协议，操作码用于区分不同的TFTP操作。以下是TFTP操作码的定义：

1. RRQ（读请求）
2. WRQ（写请求）
3. DATA（数据）
4. ACK（确认）
5. ERROR（错误）

下面分别介绍TFTP客户端和服务端的实现。

TFTP客户端：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

#define MAX_BUF_SIZE 1024

void error(char *msg)
{
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[])
{
    if (argc != 4) {
        fprintf(stderr, "Usage: %s <server_ip> <filename> <mode>\n", argv[0]);
        exit(1);
    }

    int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sockfd < 0) {
        error("Error opening socket");
    }

    struct sockaddr_in serv_addr;
    bzero(&serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = inet_addr(argv[1]);
    serv_addr.sin_port = htons(69);

    char buf[MAX_BUF_SIZE];
    char *mode = "octet";
    sprintf(buf, "%c%c%s%c%s%c", 0x00, 0x01, argv[2], 0x00, mode, 0x00);
    int n = sendto(sockfd, buf, strlen(buf), 0, (struct sockaddr *)&serv_addr, sizeof(serv_addr));
    if (n < 0) {
        error("Error sending request");
    }

    FILE *fp = fopen(argv[2], "wb");
    if (!fp) {
        error("Error opening file for writing");
    }

    int block_num = 0;
    int recv_len = 0;
    struct sockaddr_in cli_addr;
    socklen_t cli_len = sizeof(cli_addr);
    while (1) {
        bzero(buf, MAX_BUF_SIZE);
        n = recvfrom(sockfd, buf, MAX_BUF_SIZE, 0, (struct sockaddr *)&cli_addr, &cli_len);
        if (n < 0) {
            error("Error receiving data");
        }

        int opcode = ntohs(*(unsigned short *)buf);
        if (opcode == 5) {
            char *error_msg = buf + 4;
            fprintf(stderr, "Error: %s\n", error_msg);
            exit(1);
        } else if (opcode == 3) {
            int block = ntohs(*(unsigned short *)(buf + 2));
            if (block == block_num + 1) {
                fwrite(buf + 4, 1, n - 4, fp);
                block_num++;
            }

            sprintf(buf, "%c%c%c%c", 0x00, 0x04, block_num >> 8, block_num & 0xff);
            n = sendto(sockfd, buf, 4, 0, (struct sockaddr *)&cli_addr, cli_len);
            if (n < 0) {
                error("Error sending ACK");
            }

            if (n < MAX_BUF_SIZE - 4) {
                break;
            }
        }
    }

    fclose(fp);
    close(sockfd);

    return 0;
}

TFTP服务端：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>

#define MAX_BUF_SIZE 1024

void error(char *msg)
{
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[])
{
    if (argc != 2) {
        fprintf(stderr, "Usage: %s <directory>\n", argv[0]);
        exit(1);
    }

    int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sockfd < 0) {
        error("Error opening socket");
    }

    struct sockaddr_in serv_addr;
    bzero(&serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(69);

    if (bind(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
        error("Error on binding");
    }

    char buf[MAX_BUF_SIZE];
    struct sockaddr_in cli_addr;
    socklen_t cli_len = sizeof(cli_addr);
    while (1) {
        bzero(buf, MAX_BUF_SIZE);
        int n = recvfrom(sockfd, buf, MAX_BUF_SIZE, 0, (struct sockaddr *)&cli_addr, &cli_len);
        if (n < 0) {
            error("Error receiving request");
        }

        int opcode = ntohs(*(unsigned short *)buf);
        if (opcode == 1) {
            char *filename = buf + 2;
            char *mode = buf + 2 + strlen(filename) + 1;
            if (strcmp(mode, "octet") != 0) {
                char *error_msg = "Unsupported mode";
                sprintf(buf, "%c%c%c%c%s%c", 0x00, 0x05, 0x00, 0x00, error_msg, 0x00);
                sendto(sockfd, buf, strlen(buf), 0, (struct sockaddr *)&cli_addr, cli_len);
                continue;
            }

            char path[1024];
            sprintf(path, "%s/%s", argv[1], filename);
            int fd = open(path, O_RDONLY);
            if (fd < 0) {
                char *error_msg = strerror(errno);
                sprintf(buf, "%c%c%c%c%s%c", 0x00, 0x05, 0x00, 0x00, error_msg, 0x00);
                sendto(sockfd, buf, strlen(buf), 0, (struct sockaddr *)&cli_addr, cli_len);
                continue;
            }

            int block_num = 0;
            while (1) {
                bzero(buf, MAX_BUF_SIZE);
                int n = read(fd, buf + 4, MAX_BUF_SIZE - 4);
                if (n < 0) {
                    error("Error reading file");
                }

                if (n == 0) {
                    break;
                }

                *(unsigned short *)buf = htons(3);
                *(unsigned short *)(buf + 2) = htons(block_num + 1);
                sendto(sockfd, buf, n + 4, 0, (struct sockaddr *)&cli_addr, cli_len);

                while (1) {
                    bzero(buf, MAX_BUF_SIZE);
                    n = recvfrom(sockfd, buf, MAX_BUF_SIZE, 0, (struct sockaddr *)&cli_addr, &cli_len);
                    if (n < 0) {
                        error("Error receiving ACK");
                    }

                    opcode = ntohs(*(unsigned short *)buf);
                    if (opcode == 4) {
                        block_num = ntohs(*(unsigned short *)(buf + 2));
                        if (block_num == (int)(*(unsigned char *)(buf + 1))) {
                            break;
                        }
                    }
                }
            }

            close(fd);
        }
    }

    close(sockfd);

    return 0;
}