Linux pfifo_fast is the default priority queue enabled on Linux
systems. Packets are enqueued in three FIFO droptail queues according
to three priority bands based on their Type of Service bits or DSCP bits.
When a packet is passed to the Traffic Control layer, the IPv{4,6} header has not
been added yet. It will be added when the packet is dequeued from the queue disc.
Thanks to Mark Keaton for discovering and analysing the bug; he provides
an initial version of the patch, which is semantically equivalent to
the one provided in this commit.
Two test added: one for the normal slow start behavior in presence of a
normal socket (receive a packet, and ACKs the sequence number
according to the RFC) and the other with a malicious socket which sends
many small ACKs (on bad implementation this should artificially inflate
the window).
The class is responsible to take away the IP and TCP header from the packet,
and then to interrogate the pure virtual method ShouldDrop, dropping the packet
accordingly to the returned value. An implementation is a channel which
drops packet with specified flags.
The class provides a general infrastructure for a TCP-related test,
setting up the environment (two sockets connected through
SimpleNetDevice over SimpleChannel) and provides the basic management of
parameters (like segment size).
Added TcpCongestionOps class, in where the congestion control is
managed. It is created/added to a socket through TcpL4Protocol.
TcpSocketBase and the congestion algorithm classes reworked to be
compatible with the new TcpCongestionOps class.
Using the TCP without congestion control is not recommented anymore by
IETF. This patch removes the class derived from RFC793. Its behavior
could be reintroduced later with using some conditional Attributes
inside TcpSocketBase.
TcpNewReno is introduced in RFC 2582. The most recent RFC on this is
the RFC 6582. Since its introduction, Tcp NewReno is the RECOMMENDED
algorithm by the Internet Engineering Task Force. The main difference
between Reno and New Reno is in the Fast retransmit algorithm, in order
to recover more quickly when multiple packet losses occur in a single
window. NewReno introduces the concept of Partial acknowledgments. Since
the intention is to merge fast retransmit and fast recovery into
TcpSocketBase, there isn't the possibility to maintain TcpReno as
separate class. However, its behavior could be introduced again with one
conditional attribute in TcpSocketBase itself.
