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Bug 1102: IPv4 fragment offset

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This commit is contained in:
Tommaso Pecorella
2011-06-23 00:08:47 +02:00
parent 4965f16855
commit 681c4720e1
2 changed files with 18 additions and 11 deletions
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18
src/internet/model/ipv4-header.cc
View File

@@ -19,6 +19,7 @@
*/
#include "ns3/assert.h"
#include "ns3/abort.h"
#include "ns3/log.h"
#include "ns3/header.h"
#include "ipv4-header.h"
@@ -71,8 +72,6 @@ Ipv4Header::SetIdentification (uint16_t identification)
m_identification = identification;
}
void
Ipv4Header::SetTos (uint8_t tos)
{
@@ -116,15 +115,20 @@ Ipv4Header::IsDontFragment (void) const
}
void
Ipv4Header::SetFragmentOffset (uint16_t offset)
Ipv4Header::SetFragmentOffset (uint16_t offsetBytes)
{
NS_ASSERT (!(offset & (~0x3fff)));
m_fragmentOffset = offset;
// check if the user is trying to set an invalid offset
NS_ABORT_MSG_IF ((offsetBytes & 0x7), "offsetBytes must be multiple of 8 bytes");
m_fragmentOffset = offsetBytes;
}
uint16_t
Ipv4Header::GetFragmentOffset (void) const
{
NS_ASSERT (!(m_fragmentOffset & (~0x3fff)));
if ((m_fragmentOffset+m_payloadSize+5*4) > 65535)
{
NS_LOG_WARN("Fragment will exceed the maximum packet size once reassembled");
}
return m_fragmentOffset;
}
@@ -223,7 +227,7 @@ Ipv4Header::Print (std::ostream &os) const
<< "ttl " << m_ttl << " "
<< "id " << m_identification << " "
<< "protocol " << m_protocol << " "
<< "offset " << m_fragmentOffset << " "
<< "offset (bytes) " << m_fragmentOffset << " "
<< "flags [" << flags << "] "
<< "length: " << (m_payloadSize + 5 * 4)
<< " "

11
src/internet/model/ipv4-header.h
View File

@@ -70,9 +70,12 @@ public:
*/
void SetMayFragment (void);
/**
* \param offset the ipv4 fragment offset
* The offset is measured in bytes for the packet start.
* Mind that IPv4 "fragment offset" field is 13 bits long and is measured in 8-bytes words.
* Hence, the function does enforce that the offset is a multiple of 8.
* \param offsetBytes the ipv4 fragment offset measured in bytes from the start.
*/
void SetFragmentOffset (uint16_t offset);
void SetFragmentOffset (uint16_t offsetBytes);
/**
* \param ttl the ipv4 TTL
*/
@@ -110,7 +113,7 @@ public:
*/
bool IsDontFragment (void) const;
/**
* \returns the offset of this fragment.
* \returns the offset of this fragment measured in bytes from the start.
*/
uint16_t GetFragmentOffset (void) const;
/**
@@ -159,7 +162,7 @@ private:
uint32_t m_ttl : 8;
uint32_t m_protocol : 8;
uint32_t m_flags : 3;
uint16_t m_fragmentOffset : 13;
uint16_t m_fragmentOffset;
Ipv4Address m_source;
Ipv4Address m_destination;
uint16_t m_checksum;