fix: fix icmp feature

.idea/Python-web-communicate.iml

@@ -4,7 +4,7 @@
     <content url="file://$MODULE_DIR$">
       <excludeFolder url="file://$MODULE_DIR$/.venv" />
     </content>
-    <orderEntry type="jdk" jdkName="Python 3.12 (Python-web-communicate)" jdkType="Python SDK" />
+    <orderEntry type="jdk" jdkName="Python 3.13" jdkType="Python SDK" />
     <orderEntry type="sourceFolder" forTests="false" />
   </component>
 </module>

main.py

@@ -6,12 +6,38 @@ import re
 import time
 
 
+# 计算校验和
+def calculate_checksum(data):
+    checksum = 0
+    n = len(data)
+
+    # 按 16 位块划分
+    for i in range(0, n - 1, 2):
+        chunk = (data[i] << 8) + data[i + 1]
+        checksum += chunk
+
+    # 如果长度为奇数，补零
+    if n % 2 == 1:
+        checksum += data[-1] << 8
+
+    # 将 32 位总和折叠为 16 位
+    checksum = (checksum >> 16) + (checksum & 0xFFFF)
+    checksum += (checksum >> 16)
+
+    # 对总和取反
+    return ~checksum & 0xFFFF
+
+
 # 构造 ICMP 报文
 def construct_icmp():
+    # ICMP 报文头部: 类型(8), 代码(0), 校验和(0), 标识符(1), 序列号(1)
     icmp_header = struct.pack('!BBHHH', 8, 0, 0, 1, 1)
-    checksum = ~sum(icmp_header) & 0xFFFF
+    data = b'Ping'
+    # 计算校验和
+    checksum = calculate_checksum(icmp_header + data)
+    # 填充校验和字段
     icmp_header = struct.pack('!BBHHH', 8, 0, checksum, 1, 1)
-    return icmp_header
+    return icmp_header + data
 
 
 # 构造 UDP 报文