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| 1 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */ |
| 2 /* |
| 3 * Copyright (c) 2010 Adrian Sai-wah Tam |
| 4 * |
| 5 * This program is free software; you can redistribute it and/or modify |
| 6 * it under the terms of the GNU General Public License version 2 as |
| 7 * published by the Free Software Foundation; |
| 8 * |
| 9 * This program is distributed in the hope that it will be useful, |
| 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 * GNU General Public License for more details. |
| 13 * |
| 14 * You should have received a copy of the GNU General Public License |
| 15 * along with this program; if not, write to the Free Software |
| 16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 17 * |
| 18 * Author: Adrian Sai-wah Tam <adrian.sw.tam@gmail.com> |
| 19 */ |
| 20 |
| 21 #include <iostream> |
| 22 #include <algorithm> |
| 23 #include <string.h> |
| 24 #include "ns3/packet.h" |
| 25 #include "ns3/fatal-error.h" |
| 26 #include "ns3/log.h" |
| 27 #include "tcp-tx-buffer.h" |
| 28 |
| 29 NS_LOG_COMPONENT_DEFINE ("TcpTxBuffer"); |
| 30 |
| 31 namespace ns3 { |
| 32 |
| 33 TypeId |
| 34 TcpTxBuffer::GetTypeId (void) |
| 35 { |
| 36 static TypeId tid = TypeId ("ns3::TcpTxBuffer") |
| 37 .SetParent<Object> () |
| 38 .AddConstructor<TcpTxBuffer> () |
| 39 .AddTraceSource ("UnackSequence", |
| 40 "First unacknowledged sequence number (SND.UNA)", |
| 41 MakeTraceSourceAccessor (&TcpTxBuffer::m_firstByteSeq)) |
| 42 ; |
| 43 return tid; |
| 44 } |
| 45 |
| 46 /* A user is supposed to create a TcpSocket through a factory. In TcpSocket, |
| 47 * there are attributes SndBufSize and RcvBufSize to control the default Tx and |
| 48 * Rx window sizes respectively, with default of 128 KiByte. The attribute |
| 49 * SndBufSize is passed to TcpTxBuffer by TcpSocketBase::SetSndBufSize() and in |
| 50 * turn, TcpTxBuffer:SetMaxBufferSize(). Therefore, the m_maxBuffer value |
| 51 * initialized below is insignificant. |
| 52 */ |
| 53 TcpTxBuffer::TcpTxBuffer (uint32_t n) |
| 54 : m_firstByteSeq(n), m_size (0), m_maxBuffer(32768), m_data (0) |
| 55 { |
| 56 } |
| 57 |
| 58 TcpTxBuffer::~TcpTxBuffer (void) |
| 59 { |
| 60 } |
| 61 |
| 62 SequenceNumber32 |
| 63 TcpTxBuffer::HeadSequence (void) const |
| 64 { |
| 65 return m_firstByteSeq; |
| 66 } |
| 67 |
| 68 SequenceNumber32 |
| 69 TcpTxBuffer::TailSequence (void) const |
| 70 { |
| 71 return m_firstByteSeq + SequenceNumber32 (m_size); |
| 72 } |
| 73 |
| 74 uint32_t |
| 75 TcpTxBuffer::Size (void) const |
| 76 { |
| 77 return m_size; |
| 78 } |
| 79 |
| 80 uint32_t |
| 81 TcpTxBuffer::MaxBufferSize (void) const |
| 82 { |
| 83 return m_maxBuffer; |
| 84 } |
| 85 |
| 86 void |
| 87 TcpTxBuffer::SetMaxBufferSize (uint32_t n) |
| 88 { |
| 89 m_maxBuffer = n; |
| 90 } |
| 91 |
| 92 uint32_t |
| 93 TcpTxBuffer::Available (void) const |
| 94 { |
| 95 return m_maxBuffer - m_size; |
| 96 } |
| 97 |
| 98 bool |
| 99 TcpTxBuffer::Add (Ptr<Packet> p) |
| 100 { |
| 101 NS_LOG_FUNCTION (this << p); |
| 102 NS_LOG_LOGIC ("Packet of size " << p->GetSize () << " appending to window star
ting at " |
| 103 << m_firstByteSeq << ", availSize="<< Available ()); |
| 104 if (p->GetSize () <= Available ()) |
| 105 { |
| 106 if (p->GetSize () > 0) |
| 107 { |
| 108 m_data.push_back (p); |
| 109 m_size += p->GetSize (); |
| 110 NS_LOG_LOGIC ("Updated size=" << m_size << ", lastSeq=" << m_firstByte
Seq + SequenceNumber32 (m_size)); |
| 111 } |
| 112 return true; |
| 113 } |
| 114 NS_LOG_LOGIC ("Rejected. Not enough room to buffer packet."); |
| 115 return false; |
| 116 } |
| 117 |
| 118 uint32_t |
| 119 TcpTxBuffer::SizeFromSequence (const SequenceNumber32& seq) const |
| 120 { |
| 121 NS_LOG_FUNCTION (this << seq); |
| 122 // Sequence of last byte in buffer |
| 123 SequenceNumber32 lastSeq = m_firstByteSeq + SequenceNumber32 (m_size); |
| 124 // Non-negative size |
| 125 NS_LOG_LOGIC ("HeadSeq=" << m_firstByteSeq << ", lastSeq=" << lastSeq << ", si
ze=" << m_size << |
| 126 ", returns " << lastSeq - seq); |
| 127 return lastSeq - seq; |
| 128 } |
| 129 |
| 130 Ptr<Packet> |
| 131 TcpTxBuffer::CopyFromSequence (uint32_t numBytes, const SequenceNumber32& seq) |
| 132 { |
| 133 NS_LOG_FUNCTION (this << numBytes << seq); |
| 134 uint32_t s = std::min (numBytes, SizeFromSequence (seq)); // Real size to extr
act. Insure not beyond end of data |
| 135 if (s == 0) |
| 136 { |
| 137 return Create<Packet> (); // Empty packet returned |
| 138 } |
| 139 if (m_data.size () == 0) |
| 140 { // No actual data, just return dummy-data packet of correct size |
| 141 return Create<Packet> (s); |
| 142 } |
| 143 |
| 144 // Extract data from the buffer and return |
| 145 uint32_t offset = seq - m_firstByteSeq.Get (); |
| 146 uint32_t count = 0; // Offset of the first byte of a packet in the buffer |
| 147 uint32_t pktSize = 0; |
| 148 bool beginFound = false; |
| 149 int pktCount = 0; |
| 150 Ptr<Packet> outPacket; |
| 151 NS_LOG_LOGIC ("There are " << m_data.size () << " number of packets in buffer"
); |
| 152 for (BufIterator i = m_data.begin (); i != m_data.end (); ++i) |
| 153 { |
| 154 pktCount++; |
| 155 pktSize = (*i)->GetSize (); |
| 156 if (!beginFound) |
| 157 { // Look for first fragment |
| 158 if (count + pktSize > offset) |
| 159 { |
| 160 NS_LOG_LOGIC ("First byte found in packet #" << pktCount << " at b
uffer offset " << count |
| 161 << ", packet len=" << pktSize); |
| 162 beginFound = true; |
| 163 uint32_t packetOffset = offset - count; |
| 164 uint32_t fragmentLength = count + pktSize - offset; |
| 165 if (fragmentLength >= s) |
| 166 { // Data to be copied falls entirely in this packet |
| 167 return (*i)->CreateFragment (packetOffset, s); |
| 168 } |
| 169 else |
| 170 { // This packet only fulfills part of the request |
| 171 outPacket = (*i)->CreateFragment (packetOffset, fragmentLength
); |
| 172 } |
| 173 NS_LOG_LOGIC ("Output packet is now of size " << outPacket->GetSiz
e ()); |
| 174 } |
| 175 } |
| 176 else if (count + pktSize >= offset + s) |
| 177 { // Last packet fragment found |
| 178 NS_LOG_LOGIC ("Last byte found in packet #" << pktCount << " at buffer
offset " << count |
| 179 << ", packet len=" << pktSize); |
| 180 uint32_t fragmentLength = offset + s - count; |
| 181 Ptr<Packet> endFragment = (*i)->CreateFragment (0, fragmentLength); |
| 182 outPacket->AddAtEnd (endFragment); |
| 183 NS_LOG_LOGIC ("Output packet is now of size " << outPacket->GetSize ()
); |
| 184 break; |
| 185 } |
| 186 else |
| 187 { |
| 188 NS_LOG_LOGIC ("Appending to output the packet #" << pktCount << " of o
ffset " << count << " len=" << pktSize); |
| 189 outPacket->AddAtEnd (*i); |
| 190 NS_LOG_LOGIC ("Output packet is now of size " << outPacket->GetSize ()
); |
| 191 } |
| 192 count += pktSize; |
| 193 } |
| 194 NS_ASSERT (outPacket->GetSize () == s); |
| 195 return outPacket; |
| 196 } |
| 197 |
| 198 void |
| 199 TcpTxBuffer::SetHeadSequence (const SequenceNumber32& seq) |
| 200 { |
| 201 NS_LOG_FUNCTION (this << seq); |
| 202 m_firstByteSeq = seq; |
| 203 } |
| 204 |
| 205 void |
| 206 TcpTxBuffer::DiscardUpTo (const SequenceNumber32& seq) |
| 207 { |
| 208 NS_LOG_FUNCTION (this << seq); |
| 209 NS_LOG_LOGIC ("current data size=" << m_size << ", headSeq=" << m_firstByteSeq
<< ", maxBuffer=" << m_maxBuffer |
| 210 << ", numPkts=" << m_data.size ()); |
| 211 // Cases do not need to scan the buffer |
| 212 if (m_firstByteSeq >= seq) return; |
| 213 |
| 214 // Scan the buffer and discard packets |
| 215 uint32_t offset = seq - m_firstByteSeq.Get (); // Number of bytes to remove |
| 216 uint32_t pktSize; |
| 217 NS_LOG_LOGIC ("Offset=" << offset); |
| 218 BufIterator i = m_data.begin (); |
| 219 while (i != m_data.end ()) |
| 220 { |
| 221 if (offset > (*i)->GetSize ()) |
| 222 { // This packet is behind the seqnum. Remove this packet from the buffe
r |
| 223 pktSize = (*i)->GetSize (); |
| 224 m_size -= pktSize; |
| 225 offset -= pktSize; |
| 226 m_firstByteSeq += pktSize; |
| 227 i = m_data.erase (i); |
| 228 NS_LOG_LOGIC ("Removed one packet of size " << pktSize << ", offset="
<< offset); |
| 229 } |
| 230 else if (offset > 0) |
| 231 { // Part of the packet is behind the seqnum. Fragment |
| 232 pktSize = (*i)->GetSize () - offset; |
| 233 *i = (*i)->CreateFragment (offset, pktSize); |
| 234 m_size -= offset; |
| 235 m_firstByteSeq += offset; |
| 236 NS_LOG_LOGIC ("Fragmented one packet by size " << offset << ", new siz
e=" << pktSize); |
| 237 break; |
| 238 } |
| 239 } |
| 240 // Catching the case of ACKing a FIN |
| 241 if (m_size == 0) |
| 242 { |
| 243 m_firstByteSeq = seq; |
| 244 } |
| 245 NS_LOG_LOGIC ("size=" << m_size << " headSeq=" << m_firstByteSeq << " maxBuffe
r=" << m_maxBuffer |
| 246 <<" numPkts="<< m_data.size ()); |
| 247 NS_ASSERT (m_firstByteSeq == seq); |
| 248 } |
| 249 |
| 250 } // namepsace ns3 |
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