From 4da2fbfca2bdce3021e13cebb0a7a2685a6f3d9e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Deronne?= <sebastien.deronne@gmail.com>
Date: Wed, 23 Jul 2025 20:06:11 +0200
Subject: [PATCH] network: Fix alignment for TSFT radiotap subfield

---
 src/network/utils/radiotap-header.cc | 24 ++++++++++++++++++++----
 src/network/utils/radiotap-header.h  | 22 ++++++++++++++++++++--
 2 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/src/network/utils/radiotap-header.cc b/src/network/utils/radiotap-header.cc
index 33fe6ae89..52e98c225 100644
--- a/src/network/utils/radiotap-header.cc
+++ b/src/network/utils/radiotap-header.cc
@@ -72,7 +72,7 @@ RadiotapHeader::Serialize(Buffer::Iterator start) const
     //
     if (m_present & RADIOTAP_TSFT) // bit 0
     {
-        start.WriteU64(m_tsft);
+        SerializeTsft(start);
     }
 
     //
@@ -307,8 +307,7 @@ RadiotapHeader::Deserialize(Buffer::Iterator start)
     //
     if (m_present & RADIOTAP_TSFT) // bit 0
     {
-        m_tsft = start.ReadU64();
-        bytesRead += 8;
+        bytesRead += DeserializeTsft(start, bytesRead);
     }
 
     //
@@ -575,14 +574,31 @@ RadiotapHeader::SetTsft(uint64_t value)
     NS_LOG_FUNCTION(this << value);
 
     NS_ASSERT_MSG(!(m_present & RADIOTAP_TSFT), "TSFT radiotap field already present");
+    m_tsftPad = ((8 - m_length % 8) % 8);
     m_present |= RADIOTAP_TSFT;
-    m_length += 8;
+    m_length += 8 + m_tsftPad;
     m_tsft = value;
 
     NS_LOG_LOGIC(this << " m_length=" << m_length << " m_present=0x" << std::hex << m_present
                       << std::dec);
 }
 
+void
+RadiotapHeader::SerializeTsft(Buffer::Iterator& start) const
+{
+    start.WriteU8(0, m_tsftPad);
+    start.WriteU64(m_tsft);
+}
+
+uint32_t
+RadiotapHeader::DeserializeTsft(Buffer::Iterator start, uint32_t bytesRead)
+{
+    m_tsftPad = ((8 - bytesRead % 8) % 8);
+    start.Next(m_tsftPad);
+    m_tsft = start.ReadU64();
+    return sizeof(m_tsft) + m_tsftPad;
+}
+
 void
 RadiotapHeader::SetFrameFlags(uint8_t flags)
 {
diff --git a/src/network/utils/radiotap-header.h b/src/network/utils/radiotap-header.h
index 94e214e16..501b81130 100644
--- a/src/network/utils/radiotap-header.h
+++ b/src/network/utils/radiotap-header.h
@@ -773,6 +773,23 @@ class RadiotapHeader : public Header
     void SetEhtFields(const EhtFields& ehtFields);
 
   private:
+    /**
+     * Serialize the TSFT radiotap header.
+     *
+     * @param start An iterator which points to where the header should be written.
+     */
+    void SerializeTsft(Buffer::Iterator& start) const;
+
+    /**
+     * Deserialize the TSFT radiotap header.
+     *
+     * @param start An iterator which points to where the header should be read.
+     * @param bytesRead the number of bytes already read.
+
+     * @returns The number of bytes read.
+     */
+    uint32_t DeserializeTsft(Buffer::Iterator start, uint32_t bytesRead);
+
     /**
      * Serialize the Channel radiotap header.
      *
@@ -1035,8 +1052,9 @@ class RadiotapHeader : public Header
     uint32_t m_present{0};                  //!< bits describing which fields follow header
     std::optional<uint32_t> m_presentExt{}; //!< optional extended present bitmask
 
-    uint64_t m_tsft{0}; //!< Time Synchronization Function Timer (when the first bit of the MPDU
-                        //!< arrived at the MAC)
+    uint8_t m_tsftPad{0}; //!< TSFT padding.
+    uint64_t m_tsft{0};   //!< Time Synchronization Function Timer (when the first bit of the MPDU
+                          //!< arrived at the MAC)
 
     uint8_t m_flags{FRAME_FLAG_NONE}; //!< Properties of transmitted and received frames.