From 3d30065c172c56713c2959fdc1d02e3d19cc3161 Mon Sep 17 00:00:00 2001
From: DavadDi <dwh0403@163.com>
Date: Thu, 29 Jul 2021 11:45:27 +0800
Subject: [PATCH] Create tcp_mss.py

---
 kprobe_ko_ex/tcp_mss.py | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 kprobe_ko_ex/tcp_mss.py

diff --git a/kprobe_ko_ex/tcp_mss.py b/kprobe_ko_ex/tcp_mss.py
new file mode 100644
index 0000000..9cc24df
--- /dev/null
+++ b/kprobe_ko_ex/tcp_mss.py
@@ -0,0 +1,28 @@
+#!/usr/bin/python
+
+from bcc import BPF
+
+text="""
+#ifndef KBUILD_MODNAME
+#define KBUILD_MODNAME "bcc"
+#endif
+#include <linux/ip.h>
+#include <linux/tcp.h>
+#include <net/ip.h>
+#include <uapi/linux/bpf.h>
+
+int  kretprobe__tcp_current_mss(struct pt_regs *ctx) {
+	struct sock *sk = (void *)PT_REGS_PARM1(ctx);
+	u32 mss = PT_REGS_RC(ctx);
+
+	if (!sk) {
+		return 0;
+	}
+
+	bpf_trace_printk("sk 0x%lx mss: %d\\n", sk, mss);
+
+	return 0;
+}
+"""
+
+BPF(text=text).trace_print()