Socket实现的Web Server仅端口80可用，非80端口报ERR_INVALID_HTTP_RESPONSE

原代码 #

from socket import *
import sys

serverSocket = socket(AF_INET, SOCK_STREAM) 
serverPort = 100 

serverSocket.bind('',serverPort) 

serverSocket.listen(1)

while True:

    connectionSocket,addr = serverSocket.accept() 
    try:
        message = connectionSocket.recv(4096).decode()
        filename = message.split()[1][1:]
        with open(filename,"rb") as f:
            output = f.read()

        print(output)

        
        connectionSocket.sendall(output)
        print("Sent successfully.")
        connectionSocket.close()

    except:
        response = b"HTTP/1.1 404 Not Found \r\n\r\n" 
        connectionSocket.send(response)
        connectionSocket.close()

serverSocket.close()

问题原因 #

核心问题是代码返回的响应缺少完整的HTTP协议头：

• 当使用80端口时，浏览器默认该端口对应HTTP服务，会“宽容”地尝试解析无协议头的内容；但切换到非80端口后，浏览器对HTTP协议合规性检查更严格，必须收到完整的响应头才能识别有效响应。
• 你的代码在读取文件后直接发送文件内容（比如HTML），没有添加HTTP状态行、响应头（如Content-Type、Content-Length），浏览器无法识别这是合法的HTTP响应，因此抛出ERR_INVALID_HTTP_RESPONSE错误。

解决方案 #

修改成功分支代码，构建符合HTTP规范的完整响应：

from socket import *
import sys

serverSocket = socket(AF_INET, SOCK_STREAM) 
serverPort = 100 

serverSocket.bind(('', serverPort)) 

serverSocket.listen(1)

while True:
    connectionSocket, addr = serverSocket.accept() 
    try:
        message = connectionSocket.recv(4096).decode()
        filename = message.split()[1][1:]
        with open(filename, "rb") as f:
            output = f.read()
        
        # 构建完整HTTP响应
        response_header = b"HTTP/1.1 200 OK\r\n"
        # 根据文件类型调整Content-Type，比如图片用image/jpeg，css用text/css
        response_header += b"Content-Type: text/html\r\n"
        response_header += b"Content-Length: " + str(len(output)).encode() + b"\r\n"
        response_header += b"\r\n"  # 响应头与响应体的分隔符
        full_response = response_header + output
        
        connectionSocket.sendall(full_response)
        print("Sent successfully.")
        connectionSocket.close()

    except Exception as e:
        print(f"Error: {e}")
        response = b"HTTP/1.1 404 Not Found\r\n\r\n" 
        connectionSocket.send(response)
        connectionSocket.close()

serverSocket.close()

补充说明 #

• HTTP响应必须包含状态行、响应头，最后用\r\n\r\n分隔响应头和响应体，这是协议强制要求。
• 需根据实际文件类型动态设置Content-Type，否则浏览器可能无法正确渲染内容。

内容的提问来源于stack exchange，提问作者Davut Boztaş