[作品提交] 【得捷电子Follow me第4期】终极任务：FTP服务器技术实现及分析总结

alanlan86 2024-2-25 12:22 楼主

# 任务目标
- 使用主控板内存储和以太网接口，实现轻量ftp文件服务器，可以上传、下载、删除文件
![](https://micropython.org/resources/micropython-media/boards/W5500_EVB_PICO/W5500-EVB-Pico.jpg)

# 理论
- 根据百度百科可以查得：
FTP服务器（File Transfer Protocol Server）是在互联网上提供文件存储和访问服务的计算机，它们依照FTP协议提供服务。 FTP是File Transfer Protocol(文件传输协议)。顾名思义，就是专门用来传输文件的协议。简单地说，支持FTP协议的服务器就是FTP服务器。

## FTP协议
查阅FTP的协议如下图。可知FTP协议是基于TCP连接而非UDP，它分为控制连接和数据连接。稍后软件部分，可以详细找到对应的代码调用。

![](https://bkimg.cdn.bcebos.com/pic/dc54564e9258d1091af37250df58ccbf6d814dc4?x-bce-process=image/format,f_auto/watermark,image_d2F0ZXIvYmFpa2UyNzI,g_7,xp_5,yp_5,P_20/resize,m_lfit,limit_1,h_1080)

## 命令
- 可以被发送到FTP服务器的FTP命令列表，包含由IETF在RFC 959中标准化的所有命令。需要注意的是，大多数命令行FTP客户端都给用户提供了额外的命令集。例如，GET是一个常见的用来下载文件的用户命令，用来替代原始的RETR命令。

## 其他
- 为了保证FTP文件访问的安全性，FTP协议中还有关于用户登入和权限管控的部分。
- 更详细的FTP协议相关内容可以参考链接：[FTP协议详解](https://baike.baidu.com/item/ftp/13839?fromtitle=%E6%96%87%E4%BB%B6%E4%BC%A0%E8%BE%93%E5%8D%8F%E8%AE%AE&fromid=1874113 "FTP协议详解")

# 硬件 
- 采用Pico W5500 EVB及网线接入带路由器或交换器的网络，然后采用相同局域网网段的PC电脑对主控开发板进行FTP访问；
- 需要在PC端安装对应的测试软件：Xftp 7(当然使用其他支持FTP协议的PC上位机同样可以)
- Pico开发板需要刷入microPython的固件：
[Pico W5500 EVB micropython固件](https://micropython.org/download/W5500_EVB_PICO/ "Pico W5500 EVB micropython固件")

```c
Vendor: Wiznet
Features: Dual-core, Ethernet, External Flash, USB
Source on GitHub: rp2/W5500_EVB_PICO
More info: Website
Installation instructions
Flashing via UF2 bootloader
To get the board in bootloader mode ready for the firmware update, execute machine.bootloader() at the MicroPython REPL. Alternatively, hold down the BOOTSEL button while plugging the board into USB. The uf2 file below should then be copied to the USB mass storage device that appears. Once programming of the new firmware is complete the device will automatically reset and be ready for use.

Firmware
Releases
v1.22.2 (2024-02-22) .uf2 / [Release notes] (latest)
```

# 软件

## 初始化W5500
- 采用DHCP的方式初始化W5500的网络控制器，同时打印出接入网络成功之后的IP地址 DNS等信息。

```python
""" W5500 初始化 """

def w5x00_init():
    global nic
    # 网口初始化
    nic = network.WIZNET5K(spi, Pin(_CS_PIN), Pin(_RST_PIN))  # spi,cs,reset pin
    nic.active(True)
    # 配置网络
    # If you use the Dynamic IP(DHCP), you must use the "nic.ifconfig('dhcp')".
    nic.ifconfig("dhcp")
    # If you use the Static IP, you must use the  "nic.ifconfig("IP","subnet","Gateway","DNS")".
    # nic.ifconfig(('192.168.0.106','255.255.255.0','192.168.0.1','114.114.114.114'))

while not nic.isconnected():
        time.sleep(1)
        print(nic.regs())
    print("IP地址:  %s" % nic.ifconfig()[0])
    print("子网掩码: %s" % nic.ifconfig()[1])
    print("网关:    %s" % nic.ifconfig()[2])
    print("DNS:     %s" % nic.ifconfig()[3])

```

## 创建TCP套接字
- FTP Server的创建，需要依赖2个socket，分别是ftpsocket和datasocket，它们用于做网络控制和文件数据传送使用。然后端口进行bind绑定和侦听。

```python
""" 启动FTP服务 """

def ftpserver():
    DATA_PORT = 13333
    ftpsocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    datasocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

ftpsocket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    datasocket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

ftpsocket.bind(socket.getaddrinfo("0.0.0.0", 21)[0][4])
    datasocket.bind(socket.getaddrinfo("0.0.0.0", DATA_PORT)[0][4])

ftpsocket.listen(1)
    datasocket.listen(1)
    datasocket.settimeout(10)

print("FTP服务启动成功！监听端口：21")
```

## 网络命令及文件操作
- 在进行网络套接字 accept连接后，采用非阻塞方式，读出网络数据包，并解释出CWM+参数+路径，相对应的内容，进而根据对应的CMD命令执行响应回复处理。

```python
while True:
            cl, remote_addr = ftpsocket.accept()
            cl.settimeout(300)
            cwd = FTP_ROOT_PATH
            try:
                print("新的FTP连接来自: %s:%s" % (remote_addr[0], remote_addr[1]))
                cl.sendall("220 Welcome! This is the W5500_EVB_PICO!\r\n")
                while True:
                    gc.collect()
                    data = cl.readline().decode("utf-8").rstrip("\r\n")
                    if len(data) <= 0:
                        print("Client disappeared")
                        break
                    command = data.split(" ")[0].upper()
                    payload = data[len(command) :].lstrip()

path = get_absolute_path(cwd, payload)

print("命令={}, 参数={}, 路径={}".format(command, payload, path))

if command == "USER":
                        cl.sendall("230 Logged in.\r\n")
                    elif command == "SYST":
                        cl.sendall("215 UNIX Type: L8\r\n")
                    elif command == "NOOP":
                        cl.sendall("200 OK\r\n")
                    elif command == "FEAT":
                        cl.sendall("211 no-features\r\n")
                    elif command == "PWD":
                        cl.sendall('257 "{}"\r\n'.format(cwd))
                    elif command == "CWD":
                        try:
                            files = uos.listdir(path)
                            cwd = path
                            cl.sendall(msg_250_OK)
                        except:
                            cl.sendall(msg_550_fail)
                    elif command == "CDUP":
                        cwd = get_absolute_path(cwd, "..")
                        cl.sendall(msg_250_OK)
                    elif command == "TYPE":
                        # probably should switch between binary and not
                        cl.sendall("200 Transfer mode set\r\n")
                    elif command == "SIZE":
                        try:
                            size = uos.stat(path)[6]
                            cl.sendall("213 {}\r\n".format(size))
                        except:
                            cl.sendall(msg_550_fail)
                    elif command == "QUIT":
                        cl.sendall("221 Bye.\r\n")
                        break
                    elif command == "PASV":
                        addr = nic.ifconfig()[0]
                        cl.sendall(
                            "227 Entering Passive Mode ({},{},{}).\r\n".format(
                                addr.replace(".", ","), DATA_PORT >> 8, DATA_PORT % 256
                            )
                        )
                        dataclient, data_addr = datasocket.accept()
                        print("新的FTP数据连接来自: %s:%s" % (data_addr[0], data_addr[1]))
                    elif command == "LIST" or command == "NLST":
                        if not payload.startswith("-"):
                            place = path
                        else:
                            place = cwd
                        try:
                            send_list_data(
                                place, dataclient, command == "LIST" or payload == "-l"
                            )
                            cl.sendall("150 Here comes the directory listing.\r\n")
                            cl.sendall("226 Listed.\r\n")
                        except:
                            cl.sendall(msg_550_fail)
                        if dataclient is not None:
                            dataclient.close()
                            dataclient = None
                    elif command == "RETR":
                        try:
                            send_file_data(path, dataclient)
                            cl.sendall("150 Opening data connection.\r\n")
                            cl.sendall("226 Transfer complete.\r\n")
                        except:
                            cl.sendall(msg_550_fail)
                        if dataclient is not None:
                            dataclient.close()
                            dataclient = None
                    elif command == "STOR":
                        try:
                            cl.sendall("150 Ok to send data.\r\n")
                            save_file_data(path, dataclient, "wb")
                            cl.sendall("226 Transfer complete.\r\n")
                        except:
                            cl.sendall(msg_550_fail)
                        if dataclient is not None:
                            dataclient.close()
                            dataclient = None
                    elif command == "APPE":
                        try:
                            cl.sendall("150 Ok to send data.\r\n")
                            save_file_data(path, dataclient, "a")
                            cl.sendall("226 Transfer complete.\r\n")
                        except:
                            cl.sendall(msg_550_fail)
                        if dataclient is not None:
                            dataclient.close()
                            dataclient = None
                    elif command == "DELE":
                        try:
                            uos.remove(path)
                            cl.sendall(msg_250_OK)
                        except:
                            cl.sendall(msg_550_fail)
                    elif command == "RMD":
                        try:
                            uos.rmdir(path)
                            cl.sendall(msg_250_OK)
                        except:
                            cl.sendall(msg_550_fail)
                    elif command == "MKD":
                        try:
                            uos.mkdir(path)
                            cl.sendall(msg_250_OK)
                        except:
                            cl.sendall(msg_550_fail)
                    elif command == "RNFR":
                        fromname = path
                        cl.sendall("350 Rename from\r\n")
                    elif command == "RNTO":
                        if fromname is not None:
                            try:
                                uos.rename(fromname, path)
                                cl.sendall(msg_250_OK)
                            except:
                                cl.sendall(msg_550_fail)
                        else:
                            cl.sendall(msg_550_fail)
                        fromname = None
                    else:
                        cl.sendall("502 Unsupported command.\r\n")
                        # print("Unsupported command {} with payload {}".format(command, payload))
            except Exception as err:
                print(err)
            finally:
                cl.close()
                cl = None
```

## 文件操作
- 对应CMD的命令情况，需要操作micropython内部的文件存储，例如，文件列表请求、文件目录信息列举、发送文件、保存文件等等操作。

```python
""" 响应文件列表请求 """

def send_list_data(path, dataclient, full):
    try:  # whether path is a directory name
        for fname in uos.listdir(path):
            dataclient.sendall(make_description(path, fname, full))
    except:  # path may be a file name or pattern
        pattern = path.split("/")[-1]
        path = path[: -(len(pattern) + 1)]
        if path == "":
            path = "/"
        for fname in uos.listdir(path):
            if fncmp(fname, pattern) == True:
                dataclient.sendall(make_description(path, fname, full))

""" 列出目录详情 """

def make_description(path, fname, full):
    if full:
        stat = uos.stat(get_absolute_path(path, fname))
        file_permissions = (
            "drwxr-xr-x" if (stat[0] & 0o170000 == 0o040000) else "-rw-r--r--"
        )
        file_size = stat[6]
        tm = localtime(stat[7])
        if tm[0] != localtime()[0]:
            description = "{}    1 owner group {:>10} {} {:2} {:>5} {}\r\n".format(
                file_permissions, file_size, month_name[tm[1]], tm[2], tm[0], fname
            )
        else:
            description = (
                "{}    1 owner group {:>10} {} {:2} {:02}:{:02} {}\r\n".format(
                    file_permissions,
                    file_size,
                    month_name[tm[1]],
                    tm[2],
                    tm[3],
                    tm[4],
                    fname,
                )
            )
    else:
        description = fname + "\r\n"
    return description

""" 发送文件数据 """

def send_file_data(path, dataclient):
    try:
        with open(path, "rb") as file:
            chunk = file.read(512)
            print("chunk 0: ", len(chunk))
            while len(chunk) > 0:
                print("chunk: ", len(chunk))
                dataclient.sendall(chunk)
                chunk = file.read(512)
    except Exception as err:
        print("error: ", err.args, err.value, err.errno)

""" 保存文件上传数据 """

def save_file_data(path, dataclient, mode):
    with open(path, mode) as file:
        chunk = dataclient.read(512)
        while len(chunk) > 0:
            file.write(chunk)
            chunk = dataclient.read(512)

""" 获取文件绝对路径 """

def get_absolute_path(cwd, payload):
    # Just a few special cases "..", "." and ""
    # If payload start's with /, set cwd to /
    # and consider the remainder a relative path
    if payload.startswith("/"):
        cwd = "/"
    for token in payload.split("/"):
        if token == "..":
            if cwd != "/":
                cwd = "/".join(cwd.split("/")[:-1])
                if cwd == "":
                    cwd = "/"
        elif token != "." and token != "":
            if cwd == "/":
                cwd += token
            else:
                cwd = cwd + "/" + token
    return cwd

""" 文件名比较 """

def fncmp(fname, pattern):
    pi = 0
    si = 0
    while pi < len(pattern) and si < len(fname):
        if (fname[si] == pattern[pi]) or (pattern[pi] == "?"):
            si += 1
            pi += 1
        else:
            if pattern[pi] == "*":  # recurse
                if (pi + 1) == len(pattern):
                    return True
                while si < len(fname):
                    if fncmp(fname[si:], pattern[pi + 1 :]) == True:
                        return True
                    else:
                        si += 1
                return False
            else:
                return False
    if pi == len(pattern.rstrip("*")) and si == len(fname):
        return True
    else:
        return False

```
## 完整代码
- 整个测试试验用到的完整工程代码如下。

```python
import gc
import uos
import time
import socket
import network
from time import localtime
from machine import Pin, SPI
from micropython import const

_LED_PIN = const(25)  # 绿色 LED 引脚
_SPI_SPEED = const(2_000_000)  # SPI 速率
_MOSI_PIN = const(19)  # SPI MOSI 引脚
_MISO_PIN = const(16)  # SPI MISO 引脚
_SCK_PIN = const(18)  # SPI SCK 引脚
_CS_PIN = const(17)  # SPI CS 引脚
_RST_PIN = const(20)  # SPI RESET 引脚
FTP_ROOT_PATH = const("/")  # FTP 根目录

month_name = [
    "",
    "Jan",
    "Feb",
    "Mar",
    "Apr",
    "May",
    "Jun",
    "Jul",
    "Aug",
    "Sep",
    "Oct",
    "Nov",
    "Dec",
]

# SPI 定义
spi = SPI(0, _SPI_SPEED, mosi=Pin(_MOSI_PIN), miso=Pin(_MISO_PIN), sck=Pin(_SCK_PIN))
nic = None

""" W5500 初始化 """

""" 响应文件列表请求 """

""" 列出目录详情 """

""" 发送文件数据 """

""" 保存文件上传数据 """

""" 获取文件绝对路径 """

""" 文件名比较 """

""" 启动FTP服务 """

def ftpserver():
    DATA_PORT = 13333
    ftpsocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    datasocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

ftpsocket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    datasocket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

ftpsocket.bind(socket.getaddrinfo("0.0.0.0", 21)[0][4])
    datasocket.bind(socket.getaddrinfo("0.0.0.0", DATA_PORT)[0][4])

ftpsocket.listen(1)
    datasocket.listen(1)
    datasocket.settimeout(10)

print("FTP服务启动成功！监听端口：21")

msg_250_OK = "250 OK\r\n"
    msg_550_fail = "550 Failed\r\n"
    try:
        dataclient = None
        fromname = None
        while True:
            cl, remote_addr = ftpsocket.accept()
            cl.settimeout(300)
            cwd = FTP_ROOT_PATH
            try:
                print("新的FTP连接来自: %s:%s" % (remote_addr[0], remote_addr[1]))
                cl.sendall("220 Welcome! This is the W5500_EVB_PICO!\r\n")
                while True:
                    gc.collect()
                    data = cl.readline().decode("utf-8").rstrip("\r\n")
                    if len(data) <= 0:
                        print("Client disappeared")
                        break
                    command = data.split(" ")[0].upper()
                    payload = data[len(command) :].lstrip()

path = get_absolute_path(cwd, payload)

print("命令={}, 参数={}, 路径={}".format(command, payload, path))

if __name__ == "__main__":
    print("run in main")
    w5x00_init()  # 初始化网络
    ftpserver()  # 运行 FTP Server

```

# 调试

## 连接

## 上传文件

## 下载文件

## 删除文件

# 演示

# 总结

以太网是互联网时代里面最重要的通信接口和技术之一。本次Follow Me 4通过Pico W5500 EVB这块带以太网的开发板，让我们对于网络通信有了更多的了解和学习。通过抓包和网络协议的学习，扩展了大家的技术认识！

感谢EEWorld和DigiKey提供的活动平台！！！感谢~

<span class="showedittime"><i class="pstatus"> 本帖最后由 alanlan86 于 2024-2-25 12:43 编辑 </i></span>

回复评论

暂无评论，赶紧抢沙发吧