树莓派基于Python3 Socket双向通信问题：服务器无法接收客户端指令

问题描述 #

已实现树莓派1（服务器端）向树莓派2（客户端）发送消息，但服务器端无法接收客户端返回的指令，需修复该双向通信功能。

现有代码核心问题 #

1. 角色逻辑混乱：当前SERVER.py实际是主动发起连接的客户端，CLIENT.py是监听端口的服务器，命名与实际功能不符，导致通信逻辑错位。
2. 无接收返回逻辑：原服务器端仅实现发送功能，未添加监听接收客户端返回数据的代码；客户端仅接收消息，无返回指令的逻辑。
3. 端口不匹配：原服务器连接端口（5003）与客户端绑定端口（5002）不一致，会导致连接失败。

修改后的双向通信代码实现 #

修正后的服务器端（树莓派1）代码 #

服务器端负责监听端口、接收客户端连接，同时支持发送指令和接收返回：

import socket
import time

print("This is Raspberry Pi 1 as server.")

# 服务器配置
SERVER_IP = '0.0.0.0'  # 监听所有可用网卡
SERVER_PORT = 5003

# 创建套接字并初始化
server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server_socket.bind((SERVER_IP, SERVER_PORT))
server_socket.listen(1)

print(f"Server listening on {SERVER_IP}:{SERVER_PORT}")

# 等待客户端连接
client_socket, client_addr = server_socket.accept()
print(f"Connected to client: {client_addr}")

def send_command():
    command = input("Enter command to send to client (or 'exit' to quit): ")
    if command.lower() == 'exit':
        client_socket.close()
        server_socket.close()
        exit()
    try:
        client_socket.sendall(command.encode('utf-8'))
        print(f"Sent command: {command}")
    except Exception as e:
        print(f"Failed to send command: {e}")

def receive_response():
    try:
        response = client_socket.recv(1024)
        if response:
            response_str = response.decode('utf-8')
            print(f"Received response from client: {response_str}")
        else:
            print("Client disconnected.")
            client_socket.close()
            server_socket.close()
            exit()
    except Exception as e:
        print(f"Failed to receive response: {e}")

# 主循环：发送指令并接收客户端返回
while True:
    send_command()
    time.sleep(0.5)  # 等待客户端处理指令
    receive_response()
    time.sleep(1)

修正后的客户端（树莓派2）代码 #

客户端负责连接服务器、接收指令，并返回响应：

import socket
import time

print("This is Raspberry Pi 2 as client.")

# 服务器配置（替换为树莓派1的实际IP）
SERVER_IP = '192.168.39.46'
SERVER_PORT = 5003

# 创建套接字并连接服务器
client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
try:
    client_socket.connect((SERVER_IP, SERVER_PORT))
    print(f"Connected to server {SERVER_IP}:{SERVER_PORT}")
except Exception as e:
    print(f"Failed to connect to server: {e}")
    exit()

def receive_command():
    try:
        command = client_socket.recv(1024)
        if command:
            command_str = command.decode('utf-8')
            print(f"Received command from server: {command_str}")
            return command_str
        else:
            print("Server disconnected.")
            client_socket.close()
            exit()
    except Exception as e:
        print(f"Failed to receive command: {e}")

def send_response():
    # 可根据服务器指令生成业务响应，示例为手动输入返回内容
    response = input("Enter response to send to server: ")
    try:
        client_socket.sendall(response.encode('utf-8'))
        print(f"Sent response: {response}")
    except Exception as e:
        print(f"Failed to send response: {e}")

# 主循环：接收指令并返回响应
while True:
    cmd = receive_command()
    # 可选：添加业务逻辑处理，比如控制硬件设备
    send_response()
    time.sleep(1)

关键修改说明 #

• 角色明确：服务器端监听端口等待连接，客户端主动发起连接，符合TCP标准通信逻辑。
• 双向通信：两端均实现发送与接收函数，支持消息往返。
• 端口统一：服务器与客户端使用相同端口（5003），确保连接正常。
• 错误处理：增加异常捕获，处理连接、发送、接收过程中的异常情况。
• 交互测试：通过输入获取发送内容，方便快速验证功能。

内容的提问来源于stack exchange，提问作者Ace Pash