【得捷电子Follow me第4期】基础任务二：TCP Server服务器创建及抓包分析

alanlan86

【得捷电子Follow me第4期】基础任务二：TCP Server服务器创建及抓包分析 [复制链接]

<i class="pstatus"> 本帖最后由 alanlan86 于 2024-2-23 20:29 编辑 </i>

# 任务目标
![](http://docs.wiznet.io/assets/images/w5500_evb_pico_side-da676c5d9c41adedc0469b9f1810b81b.png)

1. 采用RP2040 Pico W5500 EVB搭建TCP Server，通过网线接入路由器/交换器
2. 可通过PC端进行TCP Client建立连接，并执行数据的下发和回传 loopback测试
3. 下发数据通过OLED屏幕展示
4. 使用wireshark抓包分析TCP数据包

------------

# 硬件连接
## 扩展底板
![](https://media-cdn.seeedstudio.com/media/catalog/product/cache/bb49d3ec4ee05b6f018e93f896b8a25d/p/i/pico_base_shield_1.png)
- 可以使用Follow Me 第1期的Seeed Studio 推出的Grove Shield扩展底板，可以便捷地将I2C进行外接，通过I2C1（SDA=7 SCL=6）连接OLED显示屏幕。

## OLED显示
![](https://bbs.eeworld.com.cn/data/attachment/forum/202306/26/193646ezvqvpqtvvao83qs.png.thumb.jpg)

OLED模块 OLED模块引出了GND、VCC、SDA和SCL，共计4个引脚。通过4pin的防呆插头可以将OLED屏幕链接到Pico的底板的I2C1。

## 其他
- 将通一个局域网内的网线分别接入开发板和PC。可以在PC端，使用arp -a命令查看一下当前局域网内的IP地址分配及使用情况

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以上截图是将开发板采用DHCP进行IP地址分配，IP地址为192.168.1.103，测试PC用的IP地址为：192.168.1.102

# 软件

## OLED显示代码

通过调用displayio，透过SSD1306的驱动，给OLED进行文本显示的刷入。

```python
import displayio
import terminalio
from adafruit_display_text import label
import adafruit_displayio_ssd1306

displayio.release_displays()

# Use for I2C
i2c = busio.I2C(scl=board.GP7, sda=board.GP6)
display_bus = displayio.I2CDisplay(i2c, device_address=0x3C)

WIDTH = 128
HEIGHT = 32  # Change to 64 if needed
BORDER = 5

display = adafruit_displayio_ssd1306.SSD1306(display_bus, width=WIDTH, height=HEIGHT)

# Make the display context
splash = displayio.Group()
display.root_group = splash

color_bitmap = displayio.Bitmap(WIDTH, HEIGHT, 1)
color_palette = displayio.Palette(1)
color_palette[0] = 0xFFFFFF  # White

bg_sprite = displayio.TileGrid(color_bitmap, pixel_shader=color_palette, x=0, y=0)
splash.append(bg_sprite)

# Draw a smaller inner rectangle
inner_bitmap = displayio.Bitmap(WIDTH - BORDER * 2, HEIGHT - BORDER * 2, 1)
inner_palette = displayio.Palette(1)
inner_palette[0] = 0x000000  # Black
inner_sprite = displayio.TileGrid(inner_bitmap, pixel_shader=inner_palette, x=BORDER, y=BORDER)
splash.append(inner_sprite)

# Draw a label
text = "Hello World!"
text_area = label.Label(
    terminalio.FONT, text=text, color=0xFFFFFF, x=28, y=HEIGHT // 2 - 1
)
splash.append(text_area)
```

## TCP Server建立
以下代码主要是创建socket套接字，并bind到server ip和port端口上，并打开listen侦听。下一步则采用accept等待client端的接入。

```python
# Initialize a socket for our server
socket.set_interface(eth)
server = socket.socket()  # Allocate socket for the server
server_ip = None  # IP address of server
server_port = 50007  # Port to listen on
server.bind((server_ip, server_port))  # Bind to IP and Port
server.listen()  # Begin listening for incoming clients
print("server listen")
```

## 数据通信
以下代码更加conn的不同状态，做不同的处理。其中SNSR_SOCK_FIN_WAIT/SNSR_SOCK_CLOSE_WAIT 用于判断套接字是否被对端断开或需要和断开连接断开，断开则关闭对应的套接字。并等待下一个client连接的建立。在连接建立之后，通过_available判断当前套接字是否有接收到有效的数据。

【温馨提醒】：如果采用例程“W5x00_Echo_Demo_TCP.py”的示例代码，不根据conn的状态进行关闭和重新accept的处理的话，那么主控板只能进行一次的连接和收发数据处理，若断开后，则无法重新建立server连接和通信了！

```python
while True:
    # Maintain DHCP lease
    eth.maintain_dhcp_lease()

if conn is None:
        conn, addr = server.accept()  # Wait for a connection from a client.
        print("socket connected")
        print(conn, addr)
    else :
        if conn._status in (
            SNSR_SOCK_FIN_WAIT,
        ):
            print("socket SNSR_SOCK_FIN_WAIT")
            conn.close()
            conn = None
        elif conn._status in (
            SNSR_SOCK_CLOSE_WAIT,
        ):
            print("socket SNSR_SOCK_CLOSE_WAIT")
            conn._disconnect()
            conn.close()
            conn = None
        else :
            # print("socket established", conn.status)
            avail = conn._available()
            if avail:
                # print("Received size:", avail)
                # data = conn.recv(0)
                data = conn._embed_recv(2048)
                if data:
                    print("DATA ptr", id(data), ",DATA Len: ", len(data))
                    print(data)
                    # 显示字符
                    #splash.remove(text_area)
                    splash.pop()
                    text = str(data)
                    text_area = label.Label(
                        terminalio.FONT, text=text, color=0xFFFFFF, x=16, y=HEIGHT // 2 - 1
                    )
                    splash.append(text_area)
                    display.show(splash)
                    conn.send(data)  # Echo message back to client
```

## 完整源码

```python
import board
import busio
import digitalio
import time
from adafruit_wiznet5k.adafruit_wiznet5k import *
import adafruit_wiznet5k.adafruit_wiznet5k_socket as socket

import displayio
import terminalio
from adafruit_display_text import label
import adafruit_displayio_ssd1306

displayio.release_displays()

# Use for I2C
i2c = busio.I2C(scl=board.GP7, sda=board.GP6)
display_bus = displayio.I2CDisplay(i2c, device_address=0x3C)

WIDTH = 128
HEIGHT = 32  # Change to 64 if needed
BORDER = 5

display = adafruit_displayio_ssd1306.SSD1306(display_bus, width=WIDTH, height=HEIGHT)

# Make the display context
splash = displayio.Group()
display.root_group = splash

color_bitmap = displayio.Bitmap(WIDTH, HEIGHT, 1)
color_palette = displayio.Palette(1)
color_palette[0] = 0xFFFFFF  # White

bg_sprite = displayio.TileGrid(color_bitmap, pixel_shader=color_palette, x=0, y=0)
splash.append(bg_sprite)

# Draw a smaller inner rectangle
inner_bitmap = displayio.Bitmap(WIDTH - BORDER * 2, HEIGHT - BORDER * 2, 1)
inner_palette = displayio.Palette(1)
inner_palette[0] = 0x000000  # Black
inner_sprite = displayio.TileGrid(inner_bitmap, pixel_shader=inner_palette, x=BORDER, y=BORDER)
splash.append(inner_sprite)

# Draw a label
text = "Hello World!"
text_area = label.Label(
    terminalio.FONT, text=text, color=0xFFFFFF, x=28, y=HEIGHT // 2 - 1
)
splash.append(text_area)

time.sleep(1)

##SPI0
SPI0_SCK = board.GP18
SPI0_TX = board.GP19
SPI0_RX = board.GP16
SPI0_CSn = board.GP17

##reset
W5x00_RSTn = board.GP20

print("Wiznet5k SimpleServer Test (DHCP)")

# Setup your network configuration below
# random MAC, later should change this value on your vendor ID
MY_MAC = (0x00, 0x01, 0x02, 0x03, 0x04, 0x05)
IP_ADDRESS = (192, 168, 1, 102)
SUBNET_MASK = (255, 255, 255, 0)
GATEWAY_ADDRESS = (192, 168, 1, 1)
#DNS_SERVER = (8, 8, 8, 8) #google公共DNS服务器
DNS_SERVER = (114, 114, 114, 114) #114DNS

led = digitalio.DigitalInOut(board.GP25)
led.direction = digitalio.Direction.OUTPUT

ethernetRst = digitalio.DigitalInOut(W5x00_RSTn)
ethernetRst.direction = digitalio.Direction.OUTPUT

# For Adafruit Ethernet FeatherWing
cs = digitalio.DigitalInOut(SPI0_CSn)
# For Particle Ethernet FeatherWing
# cs = digitalio.DigitalInOut(board.D5)
spi_bus = busio.SPI(SPI0_SCK, MOSI=SPI0_TX, MISO=SPI0_RX)

# Reset W5500 first
ethernetRst.value = False
time.sleep(1)
ethernetRst.value = True

# Initialize ethernet interface with DHCP
#eth = WIZNET5K(spi_bus, cs)
# Initialize ethernet interface without DHCP
#eth = WIZNET5K(spi_bus, cs, is_dhcp=False, mac=MY_MAC)
# Set network configuration
#eth.ifconfig = (IP_ADDRESS, SUBNET_MASK, GATEWAY_ADDRESS, DNS_SERVER)

eth = WIZNET5K(spi_bus, cs, is_dhcp=True, mac=MY_MAC, debug=False)

print("Chip Version:", eth.chip)
print("MAC Address:", [hex(i) for i in eth.mac_address])
print("My IP address is:", eth.pretty_ip(eth.ip_address))

# 显示IP地址
#splash.remove(text_area)
splash.pop()
text = "IP:" + eth.pretty_ip(eth.ip_address)
text_area = label.Label(
    terminalio.FONT, text=text, color=0xFFFFFF, x=16, y=HEIGHT // 2 - 1
)
splash.append(text_area)
display.show(splash)

# Initialize a socket for our server
socket.set_interface(eth)
server = socket.socket()  # Allocate socket for the server
server_ip = None  # IP address of server
server_port = 50007  # Port to listen on
server.bind((server_ip, server_port))  # Bind to IP and Port
server.listen()  # Begin listening for incoming clients
print("server listen")

conn = None

while True:
    # Maintain DHCP lease
    eth.maintain_dhcp_lease()

if conn is None:
        conn, addr = server.accept()  # Wait for a connection from a client.
        print("socket connected")
        print(conn, addr)
    else :
        if conn._status in (
            SNSR_SOCK_FIN_WAIT,
        ):
            print("socket SNSR_SOCK_FIN_WAIT")
            conn.close()
            conn = None
        elif conn._status in (
            SNSR_SOCK_CLOSE_WAIT,
        ):
            print("socket SNSR_SOCK_CLOSE_WAIT")
            conn._disconnect()
            conn.close()
            conn = None
        else :
            # print("socket established", conn.status)
            avail = conn._available()
            if avail:
                # print("Received size:", avail)
                # data = conn.recv(0)
                data = conn._embed_recv(2048)
                if data:
                    print("DATA ptr", id(data), ",DATA Len: ", len(data))
                    print(data)
                    # 显示字符
                    #splash.remove(text_area)
                    splash.pop()
                    text = str(data)
                    text_area = label.Label(
                        terminalio.FONT, text=text, color=0xFFFFFF, x=16, y=HEIGHT // 2 - 1
                    )
                    splash.append(text_area)
                    display.show(splash)
                    conn.send(data)  # Echo message back to client

```

## 调试输出
以下为采用PC端TCP测试工具，对TCPServer 192.168.1.103 端口50007进行连接，然后发送测试字符串。TCP Server在收到数据后，数据回传，因此界面收到返回的数据。

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以下是MUEditor端的Log信息，有建立联网后的IP地址输出以及数据回环测试的信息显示。

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## 数据抓包
从wirshark的抓包数据，可以看到标注黄色部分，则是TCP应用层传输的字符串数据。

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- 抓包文件

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<a href="javascript:;" class="loginf">111.pcapng</a>

<em class="xg1">(25.3 KB, 下载次数: 0)</em>
</span>
<div class="tip tip_4" id="attach_788339_menu" style="position: absolute; display: none" disautofocus="true">
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<div class="y">2024-2-23 20:14 上传</div>
点击文件名下载附件
抓包文件
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# 演示视频
- 通过以上代码可以实现主控板建立TCP Server，然后通过PC进行数据loopback回环测试。

# 总结

有CircuitPython 【RP2040-HAT-CircuitPython】的加持，通过简单的代码调用即可完成TCP Server的创建和测试了！赶紧来试一试你的测试吧！

Jacktang

通过简单的代码调用即可完成TCP Server的创建和测试了，确实是啊

【得捷电子Follow me第4期】基础任务二：TCP Server服务器创建及抓包分析 [复制链接]

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