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restore TCP option padding approach that avoids NOPs

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This commit is contained in:
Tom Henderson
2014-09-10 15:05:57 -07:00
parent d559ff6c4c
commit 8443885e88
2 changed files with 9 additions and 14 deletions
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15
src/internet/model/tcp-header.cc
View File

@@ -317,7 +317,9 @@ TcpHeader::Serialize (Buffer::Iterator start) const
i.WriteHtonU16 (0);
i.WriteHtonU16 (m_urgentPointer);
// Serialize options if they exists
// Serialize options if they exist
// This implementation does not presently try to align options on word
// boundaries using NOP options
uint32_t optionLen = 0;
TcpOptionList::const_iterator op;
for (op = m_options.begin (); op != m_options.end (); ++op)
@@ -327,17 +329,10 @@ TcpHeader::Serialize (Buffer::Iterator start) const
i.Next ((*op)->GetSerializedSize ());
}
// padding to word alignment; add NOPs as needed until last byte which is END
// padding to word alignment; add ENDs and/or pad values (they are the same)
while (optionLen % 4)
{
if ((optionLen % 4) == 3)
{
i.WriteU8 (TcpOption::END);
}
else
{
i.WriteU8 (TcpOption::NOP);
}
i.WriteU8 (TcpOption::END);
++optionLen;
}

8
src/internet/test/tcp-header-test.cc
View File

@@ -265,18 +265,18 @@ TcpHeaderWithRFC793OptionTestCase::OneOptionAtTime ()
buffer.GetSize (), "Header not correctly serialized");
// Inserted only 1 byte NOP, and so implementation should pad; so
// the other 3 bytes should be NOP, NOP, END
// the other 3 bytes should be END, PAD, PAD (n.b. PAD is same as END)
Buffer::Iterator i = buffer.Begin ();
i.Next (20);
uint8_t value = i.ReadU8 ();
NS_TEST_ASSERT_MSG_EQ (value, TcpOption::NOP, "NOP not present at byte 1");
value = i.ReadU8 ();
NS_TEST_ASSERT_MSG_EQ (value, TcpOption::NOP, "NOP not present at byte 2");
NS_TEST_ASSERT_MSG_EQ (value, TcpOption::END, "END not present at byte 2");
value = i.ReadU8 ();
NS_TEST_ASSERT_MSG_EQ (value, TcpOption::NOP, "NOP not present at byte 3");
NS_TEST_ASSERT_MSG_EQ (value, TcpOption::END, "pad not present at byte 3");
value = i.ReadU8 ();
NS_TEST_ASSERT_MSG_EQ (value, TcpOption::END, "END not present at byte 4");
NS_TEST_ASSERT_MSG_EQ (value, TcpOption::END, "pad not present at byte 4");
}
{