This re-works the persist timer to have the following behavior:
1) Only start persist timer when a buffered segment doesn't fit within
the current window and there is no in-fligh data. Previously, the
persist timer was always started when the window went to zero even
if there was no buffered data (since timer was managed in receive
pathway rather than transmit pathway)
2) Upon first fire of persist timer, fill the remaining window if
non-zero by splitting the unsent segment. If split segment is sent,
persist timer is stopped, RTO timer is now ensuring reliable window
updates
3) If window is already zero when persist timer fires, send 1 byte probe
4) Persist timer and zero window probe should only be active when the
following are true:
* no in-flight data (pcb->unacked == NULL)
* when there is buffered data (pcb->unsent != NULL)
* when pcb->unsent->len > pcb->snd_wnd
This commit adds a timeout to the zero-window probing (persist timer)
mechanism. LwIP has not historically had a timeout for the persist
timer, leading to unbounded blocking if connection drops during the
zero-window condition
This commit also adds two units test, one to check the RTO timeout
and a second to check the zero-window probe timeout
This commit adds TCP Appropriate Byte Counting (ABC) support based on
RFC 3465
ABC replaces the previous congestion window growth mechanism and has been
configured with limit of 2 SMSS. See task #14128 for discussion on
defaults, but the goal is to mitigate the performance impact of delayed
ACKs on congestion window growth
This commit also introduces a mechanism to track when the stack is
undergoing a period following an RTO where data is being retransmitted.
Lastly, this adds a unit test to verify RTO period tracking and some
basic ABC cwnd checking
This creates a single version of test IP addresses, netmasks, and ports.
All tests were using the same values, but duplicated in each test
This also adds const to some functions so we can use a const version
of addresses
This commit moves common defines and senqo array so they can be
re-used in mulptiple places for sequence number checking rather
than duplicated
Currently they are used in two places, but I'm anticipating needing
them in future TCP unit tests
test_tcp_fast_rexmit_wraparound correctness relied on the congestion
window being in congestion avoidance so that only a single TCP_MSS
segment is sent upon ACKing the first segment.
It's not known whether the test was relying tcp_alloc() to set ssthresh
to 0 and thus start in congestion avoidance or if the test was working by
accident until changes in b90a54f989
This fixes the test by enforcing the requirement of starting in
congestion avoidance
Signed-off-by: goldsimon <goldsimon@gmx.de>
Since allowing input validation to trip the ASSERT handler is bad,
let's just drop the packets instead if validation fails.
Signed-off-by: sg <goldsimon@gmx.de>
PBUF_LINK_ENCAPSULATION_HLEN support was introduced by 6ef7563f and
missed the fact that header size calculation/reservation using
computation like PBUF_LINK_HLEN + PBUF_IP_HLEN + ... are used all over
the source code. Hopefully fixed all of them.
An edge case in out-of-sequence TCP packet processing did not use the
appropriate macro to check if the sender overran the recieve window.
Consequently, this case sometimes evaluated to true when it shouldn't, which
resulted in various bad behavior, including trying to resize a TCP buffer to 4
gigabytes.
