From 16018e8d7eb9fdbbe76f2e018efe3ef6b76f6cd1 Mon Sep 17 00:00:00 2001
From: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
Date: Wed, 28 May 2008 08:51:27 -0700
Subject: [PATCH 01/13] add logging

---
 src/common/buffer.cc | 11 +++++++++++
 src/common/packet.cc | 17 +++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/src/common/buffer.cc b/src/common/buffer.cc
index 5c5bc3bb5..e75156fed 100644
--- a/src/common/buffer.cc
+++ b/src/common/buffer.cc
@@ -236,6 +236,7 @@ Buffer::CheckInternalState (void) const
 void
 Buffer::Initialize (uint32_t zeroSize)
 {
+  NS_LOG_FUNCTION (this << zeroSize);
   m_data = Buffer::Create (0);
 #ifdef BUFFER_HEURISTICS
   m_start = std::min (m_data->m_size, g_recommendedStart);
@@ -336,6 +337,7 @@ Buffer::GetInternalEnd (void) const
 bool
 Buffer::AddAtStart (uint32_t start)
 {
+  NS_LOG_FUNCTION (this << start);
   bool dirty;
   NS_ASSERT (CheckInternalState ());
   bool isDirty = m_data->m_count > 1 && m_start > m_data->m_dirtyStart;
@@ -385,6 +387,7 @@ Buffer::AddAtStart (uint32_t start)
 bool
 Buffer::AddAtEnd (uint32_t end)
 {
+  NS_LOG_FUNCTION (this << end);
   bool dirty;
   NS_ASSERT (CheckInternalState ());
   bool isDirty = m_data->m_count > 1 && m_end < m_data->m_dirtyEnd;
@@ -438,6 +441,7 @@ Buffer::AddAtEnd (uint32_t end)
 void
 Buffer::AddAtEnd (const Buffer &o)
 {
+  NS_LOG_FUNCTION (this << &o);
   if (m_data->m_count == 1 &&
       m_end == m_zeroAreaEnd &&
       m_end == m_data->m_dirtyEnd &&
@@ -460,6 +464,7 @@ Buffer::AddAtEnd (const Buffer &o)
       Buffer::Iterator src = o.End ();
       src.Prev (endData);
       dst.Write (src, o.End ());
+      NS_ASSERT (CheckInternalState ());
       return;
     }
 
@@ -471,11 +476,13 @@ Buffer::AddAtEnd (const Buffer &o)
   destStart.Prev (src.GetSize ());
   destStart.Write (src.Begin (), src.End ());
   *this = dst;
+  NS_ASSERT (CheckInternalState ());
 }
 
 void 
 Buffer::RemoveAtStart (uint32_t start)
 {
+  NS_LOG_FUNCTION (this << start);
   NS_ASSERT (CheckInternalState ());
   uint32_t newStart = m_start + start;
   if (newStart <= m_zeroAreaStart)
@@ -520,6 +527,7 @@ Buffer::RemoveAtStart (uint32_t start)
 void 
 Buffer::RemoveAtEnd (uint32_t end)
 {
+  NS_LOG_FUNCTION (this << end);
   NS_ASSERT (CheckInternalState ());
   uint32_t newEnd = m_end - std::min (end, m_end - m_start);
   if (newEnd > m_zeroAreaEnd)
@@ -555,6 +563,7 @@ Buffer::RemoveAtEnd (uint32_t end)
 Buffer 
 Buffer::CreateFragment (uint32_t start, uint32_t length) const
 {
+  NS_LOG_FUNCTION (this << start << length);
   NS_ASSERT (CheckInternalState ());
   Buffer tmp = *this;
   tmp.RemoveAtStart (start);
@@ -566,6 +575,7 @@ Buffer::CreateFragment (uint32_t start, uint32_t length) const
 Buffer 
 Buffer::CreateFullCopy (void) const
 {
+  NS_LOG_FUNCTION (this);
   NS_ASSERT (CheckInternalState ());
   if (m_zeroAreaEnd - m_zeroAreaStart != 0) 
     {
@@ -580,6 +590,7 @@ Buffer::CreateFullCopy (void) const
       Buffer::Iterator i = tmp.End ();
       i.Prev (dataEnd);
       i.Write (m_data->m_data+m_zeroAreaStart,dataEnd);
+      NS_ASSERT (tmp.CheckInternalState ());
       return tmp;
     }
   NS_ASSERT (CheckInternalState ());
diff --git a/src/common/packet.cc b/src/common/packet.cc
index a79ac2a7e..9244689dd 100644
--- a/src/common/packet.cc
+++ b/src/common/packet.cc
@@ -19,6 +19,9 @@
  */
 #include "packet.h"
 #include "ns3/assert.h"
+#include "ns3/log.h"
+
+NS_LOG_COMPONENT_DEFINE ("Packet");
 
 namespace ns3 {
 
@@ -156,6 +159,7 @@ Packet::Packet (const Buffer &buffer,  const TagList &tagList, const PacketMetad
 Ptr<Packet>
 Packet::CreateFragment (uint32_t start, uint32_t length) const
 {
+  NS_LOG_FUNCTION (this << start << length);
   Buffer buffer = m_buffer.CreateFragment (start, length);
   NS_ASSERT (m_buffer.GetSize () >= start + length);
   uint32_t end = m_buffer.GetSize () - (start + length);
@@ -174,6 +178,7 @@ Packet::GetSize (void) const
 void
 Packet::AddHeader (const Header &header)
 {
+  NS_LOG_FUNCTION (this << &header);
   uint32_t size = header.GetSerializedSize ();
   uint32_t orgStart = m_buffer.GetCurrentStartOffset ();
   bool resized = m_buffer.AddAtStart (size);
@@ -188,6 +193,7 @@ Packet::AddHeader (const Header &header)
 uint32_t
 Packet::RemoveHeader (Header &header)
 {
+  NS_LOG_FUNCTION (this << &header);
   uint32_t deserialized = header.Deserialize (m_buffer.Begin ());
   m_buffer.RemoveAtStart (deserialized);
   m_metadata.RemoveHeader (header, deserialized);
@@ -196,6 +202,7 @@ Packet::RemoveHeader (Header &header)
 void
 Packet::AddTrailer (const Trailer &trailer)
 {
+  NS_LOG_FUNCTION (this << &trailer);
   uint32_t size = trailer.GetSerializedSize ();
   uint32_t orgEnd = m_buffer.GetCurrentEndOffset ();
   bool resized = m_buffer.AddAtEnd (size);
@@ -211,6 +218,7 @@ Packet::AddTrailer (const Trailer &trailer)
 uint32_t
 Packet::RemoveTrailer (Trailer &trailer)
 {
+  NS_LOG_FUNCTION (this << &trailer);
   uint32_t deserialized = trailer.Deserialize (m_buffer.End ());
   m_buffer.RemoveAtEnd (deserialized);
   m_metadata.RemoveTrailer (trailer, deserialized);
@@ -220,6 +228,7 @@ Packet::RemoveTrailer (Trailer &trailer)
 void 
 Packet::AddAtEnd (Ptr<const Packet> packet)
 {
+  NS_LOG_FUNCTION (this << packet);
   uint32_t aStart = m_buffer.GetCurrentStartOffset ();
   uint32_t bEnd = packet->m_buffer.GetCurrentEndOffset ();
   m_buffer.AddAtEnd (packet->m_buffer);
@@ -235,6 +244,7 @@ Packet::AddAtEnd (Ptr<const Packet> packet)
 void
 Packet::AddPaddingAtEnd (uint32_t size)
 {
+  NS_LOG_FUNCTION (this << size);
   uint32_t orgEnd = m_buffer.GetCurrentEndOffset ();
   bool resized = m_buffer.AddAtEnd (size);
   if (resized)
@@ -247,12 +257,14 @@ Packet::AddPaddingAtEnd (uint32_t size)
 void 
 Packet::RemoveAtEnd (uint32_t size)
 {
+  NS_LOG_FUNCTION (this << size);
   m_buffer.RemoveAtEnd (size);
   m_metadata.RemoveAtEnd (size);
 }
 void 
 Packet::RemoveAtStart (uint32_t size)
 {
+  NS_LOG_FUNCTION (this << size);
   m_buffer.RemoveAtStart (size);
   m_metadata.RemoveAtStart (size);
 }
@@ -260,6 +272,7 @@ Packet::RemoveAtStart (uint32_t size)
 void 
 Packet::RemoveAllTags (void)
 {
+  NS_LOG_FUNCTION (this);
   m_tagList.RemoveAll ();
 }
 
@@ -408,12 +421,14 @@ Packet::BeginItem (void) const
 void
 Packet::EnableMetadata (void)
 {
+  NS_LOG_FUNCTION_NOARGS ();
   PacketMetadata::Enable ();
 }
 
 Buffer 
 Packet::Serialize (void) const
 {
+  NS_LOG_FUNCTION (this);
   Buffer buffer;
   uint32_t reserve;
 
@@ -441,6 +456,7 @@ Packet::Serialize (void) const
 void 
 Packet::Deserialize (Buffer buffer)
 {
+  NS_LOG_FUNCTION (this);
   Buffer buf = buffer;
   // read size
   uint32_t packetSize = buf.Begin ().ReadU32 ();
@@ -466,6 +482,7 @@ Packet::Deserialize (Buffer buffer)
 void 
 Packet::AddTag (const Tag &tag) const
 {
+  NS_LOG_FUNCTION (this << &tag);
   TagList *list = const_cast<TagList *> (&m_tagList);
   TagBuffer buffer = list->Add (tag.GetInstanceTypeId (), tag.GetSerializedSize (), 
                                  m_buffer.GetCurrentStartOffset (),

From 0c34dea05b5764c947b9c3d10b34f94061aedbe6 Mon Sep 17 00:00:00 2001
From: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
Date: Wed, 28 May 2008 10:10:47 -0700
Subject: [PATCH 02/13] kill dead code

---
 src/core/log.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/core/log.h b/src/core/log.h
index 554d16815..41b190370 100644
--- a/src/core/log.h
+++ b/src/core/log.h
@@ -327,12 +327,10 @@ public:
   bool IsNoneEnabled (void) const;
   void Enable (enum LogLevel level);
   void Disable (enum LogLevel level);
-  bool Decorate (void) const;
   char const *Name (void) const;
 private:
   int32_t     m_levels;
   char const *m_name;
-  bool        m_decorate;
 };
 
 class ParameterLogger : public std::ostream

From 31870b3bc0a3b36ac639cf04eae36122709e82ac Mon Sep 17 00:00:00 2001
From: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
Date: Wed, 28 May 2008 10:11:08 -0700
Subject: [PATCH 03/13] more logging code

---
 src/common/buffer.cc | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/src/common/buffer.cc b/src/common/buffer.cc
index e75156fed..ad3421df7 100644
--- a/src/common/buffer.cc
+++ b/src/common/buffer.cc
@@ -203,11 +203,13 @@ Buffer::Create (uint32_t size)
 
 Buffer::Buffer ()
 {
+  NS_LOG_FUNCTION (this);
   Initialize (0);
 }
 
 Buffer::Buffer (uint32_t dataSize)
 {
+  NS_LOG_FUNCTION (this << dataSize);
   Initialize (dataSize);
 }
 
@@ -225,12 +227,15 @@ Buffer::CheckInternalState (void) const
     m_start <= m_data->m_size &&
     m_zeroAreaStart <= m_data->m_size;
 
-  NS_ASSERT (offsetsOk);
-  NS_ASSERT (dirtyOk);
-  NS_ASSERT (internalSizeOk);
-
-  return m_data->m_count > 0 && offsetsOk && dirtyOk && 
-    internalSizeOk;
+  bool ok = m_data->m_count > 0 && offsetsOk && dirtyOk && internalSizeOk;
+  if (!ok)
+    {
+      LOG_INTERNAL_STATE ("check " << this << 
+                          ", " << (offsetsOk?"true":"false") << 
+                          ", " << (dirtyOk?"true":"false") << 
+                          ", " << (internalSizeOk?"true":"false") << " ");
+    }
+  return ok;
 }
 
 void
@@ -262,6 +267,7 @@ Buffer::Buffer (Buffer const&o)
     m_start (o.m_start),
     m_end (o.m_end)
 {
+  NS_LOG_FUNCTION (this << &o);
   m_data->m_count++;
   NS_ASSERT (CheckInternalState ());
 }
@@ -269,6 +275,7 @@ Buffer::Buffer (Buffer const&o)
 Buffer &
 Buffer::operator = (Buffer const&o)
 {
+  NS_LOG_FUNCTION (this << &o);
   NS_ASSERT (CheckInternalState ());
   if (m_data != o.m_data) 
     {
@@ -295,6 +302,8 @@ Buffer::operator = (Buffer const&o)
 
 Buffer::~Buffer ()
 {
+  NS_LOG_FUNCTION (this);
+  NS_ASSERT (CheckInternalState ());
   HEURISTICS (g_recommendedStart = std::max (g_recommendedStart, m_maxZeroAreaStart));
   m_data->m_count--;
   if (m_data->m_count == 0) 

From ab01dd65a4aa11e7d54a63521d4ff95ac4ffc491 Mon Sep 17 00:00:00 2001
From: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
Date: Wed, 28 May 2008 10:11:25 -0700
Subject: [PATCH 04/13] a failing testcase.

---
 src/common/packet-metadata-test.cc | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/src/common/packet-metadata-test.cc b/src/common/packet-metadata-test.cc
index e8716e551..d86de1788 100644
--- a/src/common/packet-metadata-test.cc
+++ b/src/common/packet-metadata-test.cc
@@ -291,7 +291,7 @@ PacketMetadataTest::CheckHistory (Ptr<Packet> p, const char *file, int line, uin
     if (!CheckHistory (p, __FILE__,             \
                       __LINE__, __VA_ARGS__))   \
       {                                         \
-        ok = false;                             \
+        result = false;                         \
       }                                         \
     Buffer buffer;                              \
     buffer = p->Serialize ();                   \
@@ -300,7 +300,7 @@ PacketMetadataTest::CheckHistory (Ptr<Packet> p, const char *file, int line, uin
     if (!CheckHistory (otherPacket, __FILE__,   \
                       __LINE__, __VA_ARGS__))   \
       {                                         \
-        ok = false;                             \
+        result = false;                         \
       }                                         \
   }
 
@@ -315,7 +315,7 @@ PacketMetadataTest::DoAddHeader (Ptr<Packet> p)
 bool
 PacketMetadataTest::RunTests (void)
 {
-  bool ok = true;
+  bool result = true;
 
   PacketMetadata::Enable ();
 
@@ -624,7 +624,29 @@ PacketMetadataTest::RunTests (void)
   REM_HEADER (p3, 8);
   p2->AddAtEnd (p3);
 
-  return ok;
+
+  p = Create<Packet> (1000);
+  ADD_HEADER (p, 10);
+  ADD_TRAILER (p, 5);
+  p1 = p->Copy ();
+  ADD_HEADER (p1, 20);
+  REM_HEADER (p1, 20);
+  REM_TRAILER (p1, 5);
+  NS_TEST_ASSERT_EQUAL (p->GetSize (), 1015);
+
+  
+  p = Create<Packet> (1510);
+  ADD_HEADER (p, 8);
+  ADD_HEADER (p, 25);
+  REM_HEADER (p, 25);
+  ADD_HEADER (p, 1);
+  p1 = p->CreateFragment (0, 1500);
+  p2 = p1->Copy ();
+  ADD_HEADER (p2, 24);
+  NS_TEST_ASSERT_EQUAL (p->GetSize (), 1518);
+
+
+  return result;
 }
 
 static PacketMetadataTest g_packetHistoryTest;

From 137ff47a46e2a015f789ee5b6dabe6d3f3bce8d1 Mon Sep 17 00:00:00 2001
From: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
Date: Wed, 28 May 2008 10:31:09 -0700
Subject: [PATCH 05/13] fix the testcase

---
 src/common/packet-metadata-test.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/common/packet-metadata-test.cc b/src/common/packet-metadata-test.cc
index d86de1788..1ccd92eb9 100644
--- a/src/common/packet-metadata-test.cc
+++ b/src/common/packet-metadata-test.cc
@@ -643,7 +643,7 @@ PacketMetadataTest::RunTests (void)
   p1 = p->CreateFragment (0, 1500);
   p2 = p1->Copy ();
   ADD_HEADER (p2, 24);
-  NS_TEST_ASSERT_EQUAL (p->GetSize (), 1518);
+  NS_TEST_ASSERT_EQUAL (p->GetSize (), 1519);
 
 
   return result;

From 45793c3a02016df5d41053f790d7c36c6b6f36d5 Mon Sep 17 00:00:00 2001
From: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
Date: Wed, 28 May 2008 10:47:14 -0700
Subject: [PATCH 06/13] fix new packet bug

---
 src/common/buffer.cc | 57 ++++++++++++++++++--------------------------
 src/common/buffer.h  | 16 +++++++++++--
 2 files changed, 37 insertions(+), 36 deletions(-)

diff --git a/src/common/buffer.cc b/src/common/buffer.cc
index ad3421df7..a179e3f67 100644
--- a/src/common/buffer.cc
+++ b/src/common/buffer.cc
@@ -24,10 +24,10 @@
 
 NS_LOG_COMPONENT_DEFINE ("Buffer");
 
-#define LOG_INTERNAL_STATE(y)                                                                    \
-NS_LOG_LOGIC (y << "start="<<m_start<<", end="<<m_end<<", zero start="<<m_zeroAreaStart<<              \
-          ", zero end="<<m_zeroAreaEnd<<", count="<<m_data->m_count<<", size="<<m_data->m_size<<   \
-          ", dirty start="<<m_data->m_dirtyStart<<", dirty end="<<m_data->m_dirtyEnd)
+#define LOG_INTERNAL_STATE(y)                                           \
+  NS_LOG_LOGIC (y << "start="<<m_start<<", end="<<m_end<<", zero start="<<m_zeroAreaStart<< \
+                ", zero end="<<m_zeroAreaEnd<<", count="<<m_data->m_count<<", size="<<m_data->m_size<< \
+                ", ownerId=" << m_ownerId << ", data owner=" << m_data->m_ownerId)
 
 #ifdef BUFFER_HEURISTICS
 #define HEURISTICS(x) x
@@ -58,17 +58,10 @@ struct BufferData {
    * Each buffer which references an instance holds a count.
    */
   uint32_t m_count;
+  uint32_t m_ownerId;
   /* the size of the m_data field below.
    */
   uint32_t m_size;
-  /* offset from the start of the m_data field below to the
-   * start of the area in which user bytes were written.
-   */
-  uint32_t m_dirtyStart;
-  /* offset from the start of the m_data field below to the
-   * end of the area in which user bytes were written.
-   */
-  uint32_t m_dirtyEnd;
   /* The real data buffer holds _at least_ one byte.
    * Its real size is stored in the m_size field.
    */
@@ -137,6 +130,7 @@ BufferAllocate (uint32_t reqSize)
   struct BufferData *data = reinterpret_cast<struct BufferData*>(b);
   data->m_size = reqSize;
   data->m_count = 1;
+  data->m_ownerId = 0;
   return data;
 }
 
@@ -220,19 +214,15 @@ Buffer::CheckInternalState (void) const
     m_start <= m_zeroAreaStart &&
     m_zeroAreaStart <= m_zeroAreaEnd &&
     m_zeroAreaEnd <= m_end;
-  bool dirtyOk =
-    m_start >= m_data->m_dirtyStart &&
-    m_end <= m_data->m_dirtyEnd;
   bool internalSizeOk = m_end - (m_zeroAreaEnd - m_zeroAreaStart) <= m_data->m_size &&
     m_start <= m_data->m_size &&
     m_zeroAreaStart <= m_data->m_size;
 
-  bool ok = m_data->m_count > 0 && offsetsOk && dirtyOk && internalSizeOk;
+  bool ok = m_data->m_count > 0 && offsetsOk && internalSizeOk;
   if (!ok)
     {
       LOG_INTERNAL_STATE ("check " << this << 
                           ", " << (offsetsOk?"true":"false") << 
-                          ", " << (dirtyOk?"true":"false") << 
                           ", " << (internalSizeOk?"true":"false") << " ");
     }
   return ok;
@@ -243,6 +233,7 @@ Buffer::Initialize (uint32_t zeroSize)
 {
   NS_LOG_FUNCTION (this << zeroSize);
   m_data = Buffer::Create (0);
+  m_ownerId = m_data->m_ownerId;
 #ifdef BUFFER_HEURISTICS
   m_start = std::min (m_data->m_size, g_recommendedStart);
   m_maxZeroAreaStart = m_start;
@@ -252,13 +243,12 @@ Buffer::Initialize (uint32_t zeroSize)
   m_zeroAreaStart = m_start;
   m_zeroAreaEnd = m_zeroAreaStart + zeroSize;
   m_end = m_zeroAreaEnd;
-  m_data->m_dirtyStart = m_start;
-  m_data->m_dirtyEnd = m_end;
   NS_ASSERT (CheckInternalState ());
 }
 
 Buffer::Buffer (Buffer const&o)
   : m_data (o.m_data),
+    m_ownerId (o.m_ownerId),
 #ifdef BUFFER_HEURISTICS
     m_maxZeroAreaStart (o.m_zeroAreaStart),
 #endif
@@ -286,6 +276,7 @@ Buffer::operator = (Buffer const&o)
           Recycle (m_data);
         }
       m_data = o.m_data;
+      m_ownerId = o.m_ownerId;
       m_data->m_count++;
     }
   HEURISTICS (
@@ -349,7 +340,7 @@ Buffer::AddAtStart (uint32_t start)
   NS_LOG_FUNCTION (this << start);
   bool dirty;
   NS_ASSERT (CheckInternalState ());
-  bool isDirty = m_data->m_count > 1 && m_start > m_data->m_dirtyStart;
+  bool isDirty = m_data->m_count > 1 && m_ownerId != m_data->m_ownerId;
   if (m_start >= start && !isDirty)
     {
       /* enough space in the buffer and not dirty. 
@@ -357,9 +348,11 @@ Buffer::AddAtStart (uint32_t start)
        * Before: |*****---------***|
        * After:  |***..---------***|
        */
-      NS_ASSERT (m_data->m_count == 1 || m_start == m_data->m_dirtyStart);
+      NS_ASSERT (m_data->m_count == 1 || m_ownerId == m_data->m_ownerId);
       m_start -= start;
-      dirty = m_start > m_data->m_dirtyStart;
+      dirty = m_ownerId != m_data->m_ownerId;
+      m_ownerId++;
+      m_data->m_ownerId = m_ownerId;
       HEURISTICS (g_nAddNoRealloc++);
     } 
   else
@@ -373,6 +366,7 @@ Buffer::AddAtStart (uint32_t start)
           Buffer::Recycle (m_data);
         }
       m_data = newData;
+      m_ownerId = newData->m_ownerId;
 
       int32_t delta = start - m_start;
       m_start += delta;
@@ -386,9 +380,6 @@ Buffer::AddAtStart (uint32_t start)
       HEURISTICS (g_nAddRealloc++);
     }
   HEURISTICS (m_maxZeroAreaStart = std::max (m_maxZeroAreaStart, m_zeroAreaStart));
-  // update dirty area
-  m_data->m_dirtyStart = m_start;
-  m_data->m_dirtyEnd = m_end;
   LOG_INTERNAL_STATE ("add start=" << start << ", ");
   NS_ASSERT (CheckInternalState ());
   return dirty;
@@ -399,7 +390,7 @@ Buffer::AddAtEnd (uint32_t end)
   NS_LOG_FUNCTION (this << end);
   bool dirty;
   NS_ASSERT (CheckInternalState ());
-  bool isDirty = m_data->m_count > 1 && m_end < m_data->m_dirtyEnd;
+  bool isDirty = m_data->m_count > 1 && m_ownerId != m_data->m_ownerId;
   if (GetInternalEnd () + end <= m_data->m_size && !isDirty)
     {
       /* enough space in buffer and not dirty
@@ -407,10 +398,12 @@ Buffer::AddAtEnd (uint32_t end)
        * Before: |**----*****|
        * After:  |**----...**|
        */
-      NS_ASSERT (m_data->m_count == 1 || m_end == m_data->m_dirtyEnd);
+      NS_ASSERT (m_data->m_count == 1 || m_ownerId == m_data->m_ownerId);
       m_end += end;
 
-      dirty = m_end < m_data->m_dirtyEnd;
+      dirty = m_ownerId != m_data->m_ownerId;
+      m_ownerId++;
+      m_data->m_ownerId = m_ownerId;
 
       HEURISTICS (g_nAddNoRealloc++);
     } 
@@ -425,6 +418,7 @@ Buffer::AddAtEnd (uint32_t end)
           Buffer::Recycle (m_data);
         }
       m_data = newData;
+      m_ownerId = newData->m_ownerId;
 
       int32_t delta = -m_start;
       m_zeroAreaStart += delta;
@@ -438,9 +432,6 @@ Buffer::AddAtEnd (uint32_t end)
       HEURISTICS (g_nAddRealloc++);
     } 
   HEURISTICS (m_maxZeroAreaStart = std::max (m_maxZeroAreaStart, m_zeroAreaStart));
-  // update dirty area
-  m_data->m_dirtyStart = m_start;
-  m_data->m_dirtyEnd = m_end;
   LOG_INTERNAL_STATE ("add end=" << end << ", ");
   NS_ASSERT (CheckInternalState ());
 
@@ -453,7 +444,7 @@ Buffer::AddAtEnd (const Buffer &o)
   NS_LOG_FUNCTION (this << &o);
   if (m_data->m_count == 1 &&
       m_end == m_zeroAreaEnd &&
-      m_end == m_data->m_dirtyEnd &&
+      m_ownerId == m_data->m_ownerId &&
       o.m_start == o.m_zeroAreaStart &&
       o.m_zeroAreaEnd - o.m_zeroAreaStart > 0)
     {
@@ -465,7 +456,6 @@ Buffer::AddAtEnd (const Buffer &o)
       uint32_t zeroSize = o.m_zeroAreaEnd - o.m_zeroAreaStart;
       m_zeroAreaEnd += zeroSize;
       m_end = m_zeroAreaEnd;
-      m_data->m_dirtyEnd = m_zeroAreaEnd;
       uint32_t endData = o.m_end - o.m_zeroAreaEnd;
       AddAtEnd (endData);
       Buffer::Iterator dst = End ();
@@ -750,7 +740,6 @@ Buffer::Iterator::Write (Iterator start, Iterator end)
   NS_ASSERT (start.m_current <= end.m_current);
   NS_ASSERT (start.m_zeroStart == end.m_zeroStart);
   NS_ASSERT (start.m_zeroEnd == end.m_zeroEnd);
-  NS_ASSERT (m_data != start.m_data);
   uint32_t size = end.m_current - start.m_current;
   Iterator cur = start;
   for (uint32_t i = 0; i < size; i++)
diff --git a/src/common/buffer.h b/src/common/buffer.h
index 75f93f780..452e1b66f 100644
--- a/src/common/buffer.h
+++ b/src/common/buffer.h
@@ -58,8 +58,13 @@ namespace ns3 {
  * BufferData. If the BufferData::m_count field is one, it means that
  * there exist only one instance of Buffer which references the 
  * BufferData instance so, it is safe to modify it. It is also
- * safe to modify the content of a BufferData if the modification
- * falls outside of the "dirty area" defined by the BufferData.
+ * safe to modify the content of a BufferData if someone has not yet
+ * made incompatible changes to the BufferData and we detect that
+ * case when the m_ownerId field is equal to the m_ownerId of the
+ * BufferData itself. Whenever a change potentially incompatible
+ * with other users is made to a BufferData object, we update the
+ * m_ownerId field of the BufferData to ensure that the other users
+ * will detect out modification.
  * In every other case, the BufferData must be copied before
  * being modified.
  *
@@ -481,6 +486,13 @@ private:
   /* This structure is described in the buffer.cc file.
    */
   struct BufferData *m_data;
+  /* id of the owner of the BufferData object.
+   * If this id matches the id stored in the BufferData object,
+   * we are the current owner of the data. If we are not the owner,
+   * and we need to acquire ownership before making modifications
+   * by doing a copy.
+   */
+  uint32_t m_ownerId;
 #ifdef BUFFER_HEURISTICS
   /* keep track of the maximum value of m_zeroAreaStart across
    * the lifetime of a Buffer instance. This variable is used

From 709f6a6d5bbe6c3d4b66ba17551ebaaa80fc1887 Mon Sep 17 00:00:00 2001
From: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
Date: Wed, 28 May 2008 10:47:21 -0700
Subject: [PATCH 07/13] document

---
 src/devices/wifi/constant-rate-wifi-manager.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/devices/wifi/constant-rate-wifi-manager.cc b/src/devices/wifi/constant-rate-wifi-manager.cc
index d8586c77b..7cf10936b 100644
--- a/src/devices/wifi/constant-rate-wifi-manager.cc
+++ b/src/devices/wifi/constant-rate-wifi-manager.cc
@@ -77,11 +77,11 @@ ConstantRateWifiManager::GetTypeId (void)
   static TypeId tid = TypeId ("ns3::ConstantRateWifiManager")
     .SetParent<WifiRemoteStationManager> ()
     .AddConstructor<ConstantRateWifiManager> ()
-    .AddAttribute ("DataMode", "XXX",
+    .AddAttribute ("DataMode", "The transmission mode to use for every data packet transmission",
                    StringValue ("wifia-6mbs"),
                    MakeWifiModeAccessor (&ConstantRateWifiManager::m_dataMode),
                    MakeWifiModeChecker ())
-    .AddAttribute ("ControlMode", "XXX",
+    .AddAttribute ("ControlMode", "The transmission mode to use for every control packet transmission.",
                    StringValue ("wifia-6mbs"),
                    MakeWifiModeAccessor (&ConstantRateWifiManager::m_ctlMode),
                    MakeWifiModeChecker ())

From 27e56402011a1d5d6541837b5ded52f37748b375 Mon Sep 17 00:00:00 2001
From: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
Date: Wed, 28 May 2008 11:28:06 -0700
Subject: [PATCH 08/13] the TypeId for Packet sockets is PacketSocketFactory,
 not PacketSocket. fix bug introduced by changeset c33b6d2775b7.

---
 examples/wifi-adhoc.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/examples/wifi-adhoc.cc b/examples/wifi-adhoc.cc
index 1759f3643..09cded9f0 100644
--- a/examples/wifi-adhoc.cc
+++ b/examples/wifi-adhoc.cc
@@ -102,7 +102,7 @@ Experiment::ReceivePacket (Ptr<Socket> socket)
 Ptr<Socket>
 Experiment::SetupPacketReceive (Ptr<Node> node)
 {
-  TypeId tid = TypeId::LookupByName ("ns3::PacketSocket");
+  TypeId tid = TypeId::LookupByName ("ns3::PacketSocketFactory");
   Ptr<Socket> sink = Socket::CreateSocket (node, tid);
   sink->Bind ();
   sink->SetRecvCallback (MakeCallback (&Experiment::ReceivePacket, this));
@@ -136,7 +136,7 @@ Experiment::Run (const WifiHelper &wifi)
   socket.SetPhysicalAddress (devices.Get (1)->GetAddress ());
   socket.SetProtocol (1);
 
-  OnOffHelper onoff ("ns3::PacketSocket", Address (socket));
+  OnOffHelper onoff ("ns3::PacketSocketFactory", Address (socket));
   onoff.SetAttribute ("OnTime", RandomVariableValue (ConstantVariable (250)));
   onoff.SetAttribute ("OffTime", RandomVariableValue (ConstantVariable (0)));
   onoff.SetAttribute ("DataRate", DataRateValue (DataRate (60000000)));

From 76dd4d1db490e6582942bcf1fa3bfcd3b7d38c00 Mon Sep 17 00:00:00 2001
From: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
Date: Wed, 28 May 2008 13:03:29 -0700
Subject: [PATCH 09/13] Fix off-by-2 errors

---
 src/node/address.cc | 21 ++++++++++-----------
 src/node/address.h  |  5 +++--
 src/node/socket.cc  | 19 ++-----------------
 3 files changed, 15 insertions(+), 30 deletions(-)

diff --git a/src/node/address.cc b/src/node/address.cc
index fb49bf8ce..1902324d9 100644
--- a/src/node/address.cc
+++ b/src/node/address.cc
@@ -114,21 +114,20 @@ Address::GetSerializedSize (void) const
 }
 
 void
-Address::Serialize (uint8_t* buf, uint32_t len) const
+Address::Serialize (TagBuffer buffer) const
 {
-  NS_ASSERT (len >= static_cast<uint32_t> (m_len + 2));
-  buf[0] = m_type;
-  buf[1] = m_len;
-  for (uint8_t i = 0; i < m_len; i++)
-    {
-      buf[i+2] = m_data[i];
-    }
+  buffer.WriteU8 (m_type);
+  buffer.WriteU8 (m_len);
+  buffer.Write (m_data,  m_len);
 }
 
-Address
-Address::Deserialize (const uint8_t* buf)
+void
+Address::Deserialize (TagBuffer buffer)
 {
-  return Address (buf[0], buf + 2, buf[1]);
+  m_type = buffer.ReadU8 ();
+  m_len = buffer.ReadU8 ();
+  NS_ASSERT (m_len <= MAX_SIZE);
+  buffer.Read (m_data, m_len);
 }
 
 ATTRIBUTE_HELPER_CPP (Address);
diff --git a/src/node/address.h b/src/node/address.h
index 16a8dc555..d88d5643d 100644
--- a/src/node/address.h
+++ b/src/node/address.h
@@ -5,6 +5,7 @@
 #include <ostream>
 #include "ns3/attribute.h"
 #include "ns3/attribute-helper.h"
+#include "ns3/tag-buffer.h"
 
 namespace ns3 {
 
@@ -166,14 +167,14 @@ public:
    * \param buf output buffer that gets written with this Address
    * \param len length of output buffer
    */
-  void Serialize (uint8_t* buf, uint32_t len) const;
+  void Serialize (TagBuffer buffer) const;
   /**
    * \param buf buffer to read address from
    * \returns an Address
    * 
    * The input address buffer is expected to be in host byte order format.
    */
-  static Address Deserialize (const uint8_t* buf);
+  void Deserialize (TagBuffer buffer);
 
 private:
   friend bool operator == (const Address &a, const Address &b);
diff --git a/src/node/socket.cc b/src/node/socket.cc
index 18a15b0e9..0a9aabc42 100644
--- a/src/node/socket.cc
+++ b/src/node/socket.cc
@@ -304,27 +304,12 @@ SocketRxAddressTag::GetSerializedSize (void) const
 void
 SocketRxAddressTag::Serialize (TagBuffer i) const
 {
-  uint8_t len = m_address.GetSerializedSize ();
-  uint8_t* buffer = new uint8_t[len];
-  memset (buffer, 0, len);
-  m_address.Serialize (buffer, len);
-  i.Write (buffer, len);
-  delete [] buffer;
+  m_address.Serialize (i);
 }
 void
 SocketRxAddressTag::Deserialize (TagBuffer i)
 {
-  uint8_t type = i.ReadU8 (); 
-  uint8_t len = i.ReadU8 (); 
-  // Len is the length of the address starting from buffer[2]
-  NS_ASSERT (len >= 2);
-  uint8_t* buffer = new uint8_t[len];
-  memset (buffer, 0, len);
-  buffer[0] = type;
-  buffer[1] = len;
-  i.Read (buffer+2, len); // ReadU8 consumes a byte
-  m_address = Address::Deserialize (buffer);
-  delete [] buffer;
+  m_address.Deserialize (i);
 }
 
 SocketIpTtlTag::SocketIpTtlTag ()  

From c9ccce91ed0622469b293881bc2859de39ec3742 Mon Sep 17 00:00:00 2001
From: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
Date: Wed, 28 May 2008 13:22:50 -0700
Subject: [PATCH 10/13] remove dead code

---
 src/node/socket-defaults.cc | 42 -------------------------------------
 src/node/socket-defaults.h  | 42 -------------------------------------
 2 files changed, 84 deletions(-)
 delete mode 100644 src/node/socket-defaults.cc
 delete mode 100644 src/node/socket-defaults.h

diff --git a/src/node/socket-defaults.cc b/src/node/socket-defaults.cc
deleted file mode 100644
index 20c97b980..000000000
--- a/src/node/socket-defaults.cc
+++ /dev/null
@@ -1,42 +0,0 @@
-/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation;
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
- *
- */
-#include "socket-defaults.h"
-#include "ns3/uinteger.h"
-
-namespace ns3 {
-
-NS_OBJECT_ENSURE_REGISTERED (SocketDefaults);
-
-TypeId SocketDefaults::GetTypeId (void)
-{
-  static TypeId tid = TypeId ("ns3::SocketDefaults")
-    .SetParent<Object> ()
-    .AddAttribute ("DefaultSndBufLimit",
-                   "Default maximum receive buffer size (bytes)",
-                   UintegerValue (0xffffffffl),
-                   MakeUintegerAccessor (&SocketDefaults::m_defaultSndBufLimit),
-                   MakeUintegerChecker<uint32_t> ())
-    .AddAttribute ("DefaultRcvBufLimit",
-                   "Default maximum receive buffer size (bytes)",
-                   UintegerValue (0xffffffffl),
-                   MakeUintegerAccessor (&SocketDefaults::m_defaultRcvBufLimit),
-                   MakeUintegerChecker<uint32_t> ())
-    ;
-  return tid;
-}
-
-} // namespace ns3
diff --git a/src/node/socket-defaults.h b/src/node/socket-defaults.h
deleted file mode 100644
index e6eb290fb..000000000
--- a/src/node/socket-defaults.h
+++ /dev/null
@@ -1,42 +0,0 @@
-/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation;
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
- */
-#ifndef SOCKET_DEFAULTS_H
-#define SOCKET_DEFAULTS_H
-
-#include "ns3/object.h"
-
-namespace ns3 {
-
-/**
- * \brief Object to hold socket option defaults
- *
- * This class can be aggregated to a Node and can be used to store
- * socket defaults for a Node.  
- * 
- */
-class SocketDefaults : public Object
-{
-public:
-  static TypeId GetTypeId (void);
-
-private:
-  uint32_t m_defaultSndBufLimit;
-  uint32_t m_defaultRcvBufLimit;
-};
-
-} // namespace ns3
-
-#endif /* SOCKET_DEFAULTS_H */

From 08961f48837167b9cf0ee9a7207262619a9b9139 Mon Sep 17 00:00:00 2001
From: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
Date: Wed, 28 May 2008 13:59:53 -0700
Subject: [PATCH 11/13] make sure that the mac low listener is destroyed
 _after_ the mac low itself.

---
 src/devices/wifi/dca-txop.cc | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/devices/wifi/dca-txop.cc b/src/devices/wifi/dca-txop.cc
index 9eee9cb9d..83282f011 100644
--- a/src/devices/wifi/dca-txop.cc
+++ b/src/devices/wifi/dca-txop.cc
@@ -139,10 +139,6 @@ void
 DcaTxop::DoDispose (void)
 {
   NS_LOG_FUNCTION (this);
-  delete m_transmissionListener;
-  delete m_dcf;
-  delete m_rng;
-  delete m_txMiddle;
   m_transmissionListener = 0;
   m_dcf = 0;
   m_rng = 0;
@@ -150,6 +146,10 @@ DcaTxop::DoDispose (void)
   m_queue = 0;
   m_low = 0;
   m_stationManager = 0;
+  delete m_transmissionListener;
+  delete m_dcf;
+  delete m_rng;
+  delete m_txMiddle;
 }
 
 void

From b851cc5b0ba65bf6134cfd6f3a2b7c2ad4e84c75 Mon Sep 17 00:00:00 2001
From: Tom Henderson <tomh@tomh.org>
Date: Wed, 28 May 2008 22:06:14 -0700
Subject: [PATCH 12/13] Undo changeset 3163 (breaks multicast)

---
 src/common/buffer.cc | 57 ++++++++++++++++++++++++++------------------
 src/common/buffer.h  | 16 ++-----------
 2 files changed, 36 insertions(+), 37 deletions(-)

diff --git a/src/common/buffer.cc b/src/common/buffer.cc
index a179e3f67..ad3421df7 100644
--- a/src/common/buffer.cc
+++ b/src/common/buffer.cc
@@ -24,10 +24,10 @@
 
 NS_LOG_COMPONENT_DEFINE ("Buffer");
 
-#define LOG_INTERNAL_STATE(y)                                           \
-  NS_LOG_LOGIC (y << "start="<<m_start<<", end="<<m_end<<", zero start="<<m_zeroAreaStart<< \
-                ", zero end="<<m_zeroAreaEnd<<", count="<<m_data->m_count<<", size="<<m_data->m_size<< \
-                ", ownerId=" << m_ownerId << ", data owner=" << m_data->m_ownerId)
+#define LOG_INTERNAL_STATE(y)                                                                    \
+NS_LOG_LOGIC (y << "start="<<m_start<<", end="<<m_end<<", zero start="<<m_zeroAreaStart<<              \
+          ", zero end="<<m_zeroAreaEnd<<", count="<<m_data->m_count<<", size="<<m_data->m_size<<   \
+          ", dirty start="<<m_data->m_dirtyStart<<", dirty end="<<m_data->m_dirtyEnd)
 
 #ifdef BUFFER_HEURISTICS
 #define HEURISTICS(x) x
@@ -58,10 +58,17 @@ struct BufferData {
    * Each buffer which references an instance holds a count.
    */
   uint32_t m_count;
-  uint32_t m_ownerId;
   /* the size of the m_data field below.
    */
   uint32_t m_size;
+  /* offset from the start of the m_data field below to the
+   * start of the area in which user bytes were written.
+   */
+  uint32_t m_dirtyStart;
+  /* offset from the start of the m_data field below to the
+   * end of the area in which user bytes were written.
+   */
+  uint32_t m_dirtyEnd;
   /* The real data buffer holds _at least_ one byte.
    * Its real size is stored in the m_size field.
    */
@@ -130,7 +137,6 @@ BufferAllocate (uint32_t reqSize)
   struct BufferData *data = reinterpret_cast<struct BufferData*>(b);
   data->m_size = reqSize;
   data->m_count = 1;
-  data->m_ownerId = 0;
   return data;
 }
 
@@ -214,15 +220,19 @@ Buffer::CheckInternalState (void) const
     m_start <= m_zeroAreaStart &&
     m_zeroAreaStart <= m_zeroAreaEnd &&
     m_zeroAreaEnd <= m_end;
+  bool dirtyOk =
+    m_start >= m_data->m_dirtyStart &&
+    m_end <= m_data->m_dirtyEnd;
   bool internalSizeOk = m_end - (m_zeroAreaEnd - m_zeroAreaStart) <= m_data->m_size &&
     m_start <= m_data->m_size &&
     m_zeroAreaStart <= m_data->m_size;
 
-  bool ok = m_data->m_count > 0 && offsetsOk && internalSizeOk;
+  bool ok = m_data->m_count > 0 && offsetsOk && dirtyOk && internalSizeOk;
   if (!ok)
     {
       LOG_INTERNAL_STATE ("check " << this << 
                           ", " << (offsetsOk?"true":"false") << 
+                          ", " << (dirtyOk?"true":"false") << 
                           ", " << (internalSizeOk?"true":"false") << " ");
     }
   return ok;
@@ -233,7 +243,6 @@ Buffer::Initialize (uint32_t zeroSize)
 {
   NS_LOG_FUNCTION (this << zeroSize);
   m_data = Buffer::Create (0);
-  m_ownerId = m_data->m_ownerId;
 #ifdef BUFFER_HEURISTICS
   m_start = std::min (m_data->m_size, g_recommendedStart);
   m_maxZeroAreaStart = m_start;
@@ -243,12 +252,13 @@ Buffer::Initialize (uint32_t zeroSize)
   m_zeroAreaStart = m_start;
   m_zeroAreaEnd = m_zeroAreaStart + zeroSize;
   m_end = m_zeroAreaEnd;
+  m_data->m_dirtyStart = m_start;
+  m_data->m_dirtyEnd = m_end;
   NS_ASSERT (CheckInternalState ());
 }
 
 Buffer::Buffer (Buffer const&o)
   : m_data (o.m_data),
-    m_ownerId (o.m_ownerId),
 #ifdef BUFFER_HEURISTICS
     m_maxZeroAreaStart (o.m_zeroAreaStart),
 #endif
@@ -276,7 +286,6 @@ Buffer::operator = (Buffer const&o)
           Recycle (m_data);
         }
       m_data = o.m_data;
-      m_ownerId = o.m_ownerId;
       m_data->m_count++;
     }
   HEURISTICS (
@@ -340,7 +349,7 @@ Buffer::AddAtStart (uint32_t start)
   NS_LOG_FUNCTION (this << start);
   bool dirty;
   NS_ASSERT (CheckInternalState ());
-  bool isDirty = m_data->m_count > 1 && m_ownerId != m_data->m_ownerId;
+  bool isDirty = m_data->m_count > 1 && m_start > m_data->m_dirtyStart;
   if (m_start >= start && !isDirty)
     {
       /* enough space in the buffer and not dirty. 
@@ -348,11 +357,9 @@ Buffer::AddAtStart (uint32_t start)
        * Before: |*****---------***|
        * After:  |***..---------***|
        */
-      NS_ASSERT (m_data->m_count == 1 || m_ownerId == m_data->m_ownerId);
+      NS_ASSERT (m_data->m_count == 1 || m_start == m_data->m_dirtyStart);
       m_start -= start;
-      dirty = m_ownerId != m_data->m_ownerId;
-      m_ownerId++;
-      m_data->m_ownerId = m_ownerId;
+      dirty = m_start > m_data->m_dirtyStart;
       HEURISTICS (g_nAddNoRealloc++);
     } 
   else
@@ -366,7 +373,6 @@ Buffer::AddAtStart (uint32_t start)
           Buffer::Recycle (m_data);
         }
       m_data = newData;
-      m_ownerId = newData->m_ownerId;
 
       int32_t delta = start - m_start;
       m_start += delta;
@@ -380,6 +386,9 @@ Buffer::AddAtStart (uint32_t start)
       HEURISTICS (g_nAddRealloc++);
     }
   HEURISTICS (m_maxZeroAreaStart = std::max (m_maxZeroAreaStart, m_zeroAreaStart));
+  // update dirty area
+  m_data->m_dirtyStart = m_start;
+  m_data->m_dirtyEnd = m_end;
   LOG_INTERNAL_STATE ("add start=" << start << ", ");
   NS_ASSERT (CheckInternalState ());
   return dirty;
@@ -390,7 +399,7 @@ Buffer::AddAtEnd (uint32_t end)
   NS_LOG_FUNCTION (this << end);
   bool dirty;
   NS_ASSERT (CheckInternalState ());
-  bool isDirty = m_data->m_count > 1 && m_ownerId != m_data->m_ownerId;
+  bool isDirty = m_data->m_count > 1 && m_end < m_data->m_dirtyEnd;
   if (GetInternalEnd () + end <= m_data->m_size && !isDirty)
     {
       /* enough space in buffer and not dirty
@@ -398,12 +407,10 @@ Buffer::AddAtEnd (uint32_t end)
        * Before: |**----*****|
        * After:  |**----...**|
        */
-      NS_ASSERT (m_data->m_count == 1 || m_ownerId == m_data->m_ownerId);
+      NS_ASSERT (m_data->m_count == 1 || m_end == m_data->m_dirtyEnd);
       m_end += end;
 
-      dirty = m_ownerId != m_data->m_ownerId;
-      m_ownerId++;
-      m_data->m_ownerId = m_ownerId;
+      dirty = m_end < m_data->m_dirtyEnd;
 
       HEURISTICS (g_nAddNoRealloc++);
     } 
@@ -418,7 +425,6 @@ Buffer::AddAtEnd (uint32_t end)
           Buffer::Recycle (m_data);
         }
       m_data = newData;
-      m_ownerId = newData->m_ownerId;
 
       int32_t delta = -m_start;
       m_zeroAreaStart += delta;
@@ -432,6 +438,9 @@ Buffer::AddAtEnd (uint32_t end)
       HEURISTICS (g_nAddRealloc++);
     } 
   HEURISTICS (m_maxZeroAreaStart = std::max (m_maxZeroAreaStart, m_zeroAreaStart));
+  // update dirty area
+  m_data->m_dirtyStart = m_start;
+  m_data->m_dirtyEnd = m_end;
   LOG_INTERNAL_STATE ("add end=" << end << ", ");
   NS_ASSERT (CheckInternalState ());
 
@@ -444,7 +453,7 @@ Buffer::AddAtEnd (const Buffer &o)
   NS_LOG_FUNCTION (this << &o);
   if (m_data->m_count == 1 &&
       m_end == m_zeroAreaEnd &&
-      m_ownerId == m_data->m_ownerId &&
+      m_end == m_data->m_dirtyEnd &&
       o.m_start == o.m_zeroAreaStart &&
       o.m_zeroAreaEnd - o.m_zeroAreaStart > 0)
     {
@@ -456,6 +465,7 @@ Buffer::AddAtEnd (const Buffer &o)
       uint32_t zeroSize = o.m_zeroAreaEnd - o.m_zeroAreaStart;
       m_zeroAreaEnd += zeroSize;
       m_end = m_zeroAreaEnd;
+      m_data->m_dirtyEnd = m_zeroAreaEnd;
       uint32_t endData = o.m_end - o.m_zeroAreaEnd;
       AddAtEnd (endData);
       Buffer::Iterator dst = End ();
@@ -740,6 +750,7 @@ Buffer::Iterator::Write (Iterator start, Iterator end)
   NS_ASSERT (start.m_current <= end.m_current);
   NS_ASSERT (start.m_zeroStart == end.m_zeroStart);
   NS_ASSERT (start.m_zeroEnd == end.m_zeroEnd);
+  NS_ASSERT (m_data != start.m_data);
   uint32_t size = end.m_current - start.m_current;
   Iterator cur = start;
   for (uint32_t i = 0; i < size; i++)
diff --git a/src/common/buffer.h b/src/common/buffer.h
index 452e1b66f..75f93f780 100644
--- a/src/common/buffer.h
+++ b/src/common/buffer.h
@@ -58,13 +58,8 @@ namespace ns3 {
  * BufferData. If the BufferData::m_count field is one, it means that
  * there exist only one instance of Buffer which references the 
  * BufferData instance so, it is safe to modify it. It is also
- * safe to modify the content of a BufferData if someone has not yet
- * made incompatible changes to the BufferData and we detect that
- * case when the m_ownerId field is equal to the m_ownerId of the
- * BufferData itself. Whenever a change potentially incompatible
- * with other users is made to a BufferData object, we update the
- * m_ownerId field of the BufferData to ensure that the other users
- * will detect out modification.
+ * safe to modify the content of a BufferData if the modification
+ * falls outside of the "dirty area" defined by the BufferData.
  * In every other case, the BufferData must be copied before
  * being modified.
  *
@@ -486,13 +481,6 @@ private:
   /* This structure is described in the buffer.cc file.
    */
   struct BufferData *m_data;
-  /* id of the owner of the BufferData object.
-   * If this id matches the id stored in the BufferData object,
-   * we are the current owner of the data. If we are not the owner,
-   * and we need to acquire ownership before making modifications
-   * by doing a copy.
-   */
-  uint32_t m_ownerId;
 #ifdef BUFFER_HEURISTICS
   /* keep track of the maximum value of m_zeroAreaStart across
    * the lifetime of a Buffer instance. This variable is used

From 41b7eadd3397da53072d858d455c461240e6bbd6 Mon Sep 17 00:00:00 2001
From: Tom Henderson <tomh@tomh.org>
Date: Wed, 28 May 2008 22:45:59 -0700
Subject: [PATCH 13/13] undo changeset 3161 (to pass unit tests)

---
 src/common/packet-metadata-test.cc | 30 ++++--------------------------
 1 file changed, 4 insertions(+), 26 deletions(-)

diff --git a/src/common/packet-metadata-test.cc b/src/common/packet-metadata-test.cc
index 1ccd92eb9..e8716e551 100644
--- a/src/common/packet-metadata-test.cc
+++ b/src/common/packet-metadata-test.cc
@@ -291,7 +291,7 @@ PacketMetadataTest::CheckHistory (Ptr<Packet> p, const char *file, int line, uin
     if (!CheckHistory (p, __FILE__,             \
                       __LINE__, __VA_ARGS__))   \
       {                                         \
-        result = false;                         \
+        ok = false;                             \
       }                                         \
     Buffer buffer;                              \
     buffer = p->Serialize ();                   \
@@ -300,7 +300,7 @@ PacketMetadataTest::CheckHistory (Ptr<Packet> p, const char *file, int line, uin
     if (!CheckHistory (otherPacket, __FILE__,   \
                       __LINE__, __VA_ARGS__))   \
       {                                         \
-        result = false;                         \
+        ok = false;                             \
       }                                         \
   }
 
@@ -315,7 +315,7 @@ PacketMetadataTest::DoAddHeader (Ptr<Packet> p)
 bool
 PacketMetadataTest::RunTests (void)
 {
-  bool result = true;
+  bool ok = true;
 
   PacketMetadata::Enable ();
 
@@ -624,29 +624,7 @@ PacketMetadataTest::RunTests (void)
   REM_HEADER (p3, 8);
   p2->AddAtEnd (p3);
 
-
-  p = Create<Packet> (1000);
-  ADD_HEADER (p, 10);
-  ADD_TRAILER (p, 5);
-  p1 = p->Copy ();
-  ADD_HEADER (p1, 20);
-  REM_HEADER (p1, 20);
-  REM_TRAILER (p1, 5);
-  NS_TEST_ASSERT_EQUAL (p->GetSize (), 1015);
-
-  
-  p = Create<Packet> (1510);
-  ADD_HEADER (p, 8);
-  ADD_HEADER (p, 25);
-  REM_HEADER (p, 25);
-  ADD_HEADER (p, 1);
-  p1 = p->CreateFragment (0, 1500);
-  p2 = p1->Copy ();
-  ADD_HEADER (p2, 24);
-  NS_TEST_ASSERT_EQUAL (p->GetSize (), 1519);
-
-
-  return result;
+  return ok;
 }
 
 static PacketMetadataTest g_packetHistoryTest;