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Rfc9293 WIP #202

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Rfc9293 WIP #202

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1113751
tcp: Remove redundant :ack-p t
ebrasca Feb 19, 2024
3b0fe68
tcp: Update the protocol specification link to rfc9293
ebrasca Feb 25, 2024
ef54dfb
tcp: Do nothing to finish segments when in state :closed or :listen
ebrasca Feb 25, 2024
c140f05
tcp: Fix errata
ebrasca Feb 25, 2024
d2c3874
tcp: Refactor acceptable-segment-p
ebrasca Feb 25, 2024
8c0a1c1
tcp: Add tcp4-send-ack
ebrasca Mar 20, 2024
e8b7f35
tcp: Add challenge-ack
ebrasca Mar 20, 2024
0e6ca64
tcp: Check the sequence numbers before accepting RST in :syn-sent
ebrasca Mar 20, 2024
bce312d
tcp: Send RST when package is from old connection in :syn-sent state
ebrasca Mar 20, 2024
fb4e215
tcp: Refactor tcp4-connection-receive :syn-sent state
ebrasca Mar 20, 2024
e91e108
tcp: ACK non RST incoming unacceptable segments
ebrasca Mar 20, 2024
5a6d095
tcp: Check incomming RST segments
ebrasca Mar 20, 2024
53363c9
tcp: Don't abort connection when resiving segment in :syn-received state
ebrasca Mar 20, 2024
cc921f7
tcp: Remove connection from listener when getting SYN in state :syn-r…
ebrasca Mar 20, 2024
d602981
tcp: Challenge any SYN segment when not in :syn-sent state
ebrasca Mar 20, 2024
352172c
tcp: Add :time-wait state
ebrasca Mar 20, 2024
663c799
tcp: Add =<
ebrasca Mar 22, 2024
9688f25
tcp: Deal with wrap around sequence numbers correctly
ebrasca Mar 22, 2024
08e01fb
tcp: Small refactor
ebrasca Mar 22, 2024
f6fa477
tcp: Send RST to segments of old connections in :syn-received state
ebrasca Mar 22, 2024
3278434
tcp: Handle FIN in :syn-received state
ebrasca Mar 22, 2024
180b7b4
tcp: Chenck ACK sequence number in :last-ack state before ending it
ebrasca Mar 22, 2024
3334d79
tcp: Hangle FIN in :last-ack state
ebrasca Mar 22, 2024
0c28348
tcp: Ignore SYN or RST packets without ACK
ebrasca Mar 22, 2024
c9a2b0d
tcp: Allow sending data in half open connection
ebrasca Mar 22, 2024
d4bf137
tcp: Add rfc5961 mitigation
ebrasca Mar 22, 2024
98af636
tcp: Send ACK to segments that acknowledges something not yet sent
ebrasca Mar 22, 2024
bfb920a
tcp: Hangle FIN in :closing state
ebrasca Mar 22, 2024
dd95347
tcp: Hangle FIN in :close-wait state
ebrasca Mar 23, 2024
0d07fa7
tcp: Allow to resive data and control in the same segment
ebrasca Mar 23, 2024
5a15692
tcp: Refactor tcp4-connection-receive :fin-wait-1 state
ebrasca Mar 23, 2024
7cf7956
tcp: Update window size
ebrasca Mar 27, 2024
b365915
arp: Use correct function to get the time
ebrasca Jul 1, 2024
4f2bd69
tcp: Report connection-closing in tcp-send when connetion is closing
ebrasca Jul 1, 2024
c229bc9
tcp: Implemented abort close
ebrasca Jul 1, 2024
24ea270
tcp: Refactor tcp-send
ebrasca Jul 9, 2024
94ebcb6
tcp: Add missing :closed case
ebrasca Jul 9, 2024
dc3eced
tcp: Implemented time-wait timeout
ebrasca Jul 10, 2024
1690e24
tcp: Add :closed case to tcp4-connection-receive
ebrasca Jul 12, 2024
fe6ae64
tcp: Add close for :syn-sent and :syn-received cases
ebrasca Jul 12, 2024
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121 changes: 64 additions & 57 deletions net/tcp.lisp
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Original file line number Diff line number Diff line change
@@ -1,14 +1,8 @@
;;; TCP
;;;
;;; Transmission Control Protocol - Protocol Specification
;;; https://tools.ietf.org/html/rfc793
;;; https://datatracker.ietf.org/doc/html/rfc9293
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;;;
;;; EFSM/SDL modeling of the original TCP standard (RFC793) and the
;;; Congestion Control Mechanism of TCP Reno
;;; http://www.medianet.kent.edu/techreports/TR2005-07-22-tcp-EFSM.pdf
;;;
;;; Computing TCP's Retransmission Timer
;;; https://tools.ietf.org/html/rfc6298

(in-package :mezzano.network.tcp)

Expand Down Expand Up @@ -383,8 +377,9 @@ Set to a value near 2^32 to test SND sequence number wrapping.")
(setf (tcp-connection-last-ack-time connection)
(get-internal-run-time))
(when (not *netmangler-force-local-retransmit*)
(tcp4-send-packet connection iss (+u32 irs 1) nil :ack-p t :syn-p t))))
(tcp4-send-packet connection iss (+u32 irs 1) nil :syn-p t))))
((logtest flags +tcp4-flag-rst+)) ; Do nothing for resets addressed to nobody.
((logtest flags +tcp4-flag-fin+)) ; Do nothing for finish since the SEG.SEQ cannot be validated
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Do you have a way to test this?

(t
(let* ((seq (if (logtest flags +tcp4-flag-ack+)
(tcp-packet-acknowledgment-number packet start end)
Expand Down Expand Up @@ -471,11 +466,7 @@ Set to a value near 2^32 to test SND sequence number wrapping.")
(when (<= seq (tcp-connection-rcv.nxt connection))
;; Don't check *netmangler-force-local-retransmit* here,
;; or no acks will ever get through.
(tcp4-send-packet connection
(tcp-connection-snd.nxt connection)
(tcp-connection-rcv.nxt connection)
nil
:ack-p t)))
(tcp4-send-ack connection)))

(defun tcp-packet-sequence-number (packet start end)
(declare (ignore end))
Expand All @@ -496,20 +487,29 @@ Set to a value near 2^32 to test SND sequence number wrapping.")
(defun tcp-packet-data-length (packet start end)
(- end (+ start (tcp-packet-header-length packet start end))))

(defun acceptable-segment-p (connection packet start end)
(defun acceptable-segment-p (connection seg.seq seg.len)
(let ((rcv.wnd (tcp-connection-rcv.wnd connection))
(rcv.nxt (tcp-connection-rcv.nxt connection))
(seg.seq (tcp-packet-sequence-number packet start end))
(seg.len (tcp-packet-data-length packet start end)))
(rcv.nxt (tcp-connection-rcv.nxt connection)))
(if (eql rcv.wnd 0)
(and (eql seg.len 0)
(eql seg.seq rcv.nxt))
;; Arithmetic here is not wrapping, so as to avoid wrap-around problems.
(and (and (<= rcv.nxt seg.seq) (< seg.seq (+ rcv.nxt rcv.wnd)))
(and (<= rcv.nxt seg.seq)
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(< seg.seq (+ rcv.nxt rcv.wnd))
(or (eql seg.len 0)
(let ((seq-end (+ seg.seq seg.len -1)))
(and (<= rcv.nxt seq-end) (< seq-end (+ rcv.nxt rcv.wnd)))))))))

(defun acceptable-ack-p (connection seg.ack)
"If SND.UNA < SEG.ACK <= SND.NXT, then the ACK is acceptable."
(if (< (tcp-connection-snd.una connection)
(tcp-connection-snd.nxt connection))
(and (< (tcp-connection-snd.una connection) seg.ack)
(<= seg.ack (tcp-connection-snd.nxt connection)))
;; Sequence numbers wrapped.
(or (< (tcp-connection-snd.una connection) seg.ack)
(<= seg.ack (tcp-connection-snd.nxt connection)))))

(defun update-timeout-timer (connection)
(when (not (eql (tcp-connection-state connection) :syn-sent))
(disarm-timeout-timer connection)
Expand Down Expand Up @@ -556,12 +556,13 @@ Set to a value near 2^32 to test SND sequence number wrapping.")
(flags (tcp-packet-flags packet start end))
(header-length (tcp-packet-header-length packet start end))
(data-length (tcp-packet-data-length packet start end)))
(when (and (not (eql (tcp-connection-state connection) :established))
(logtest flags +tcp4-flag-rst+))
(when (and (logtest flags +tcp4-flag-rst+)
(not (or (eql (tcp-connection-state connection) :syn-sent)
(eql (tcp-connection-state connection) :established))))
;; FIXME: This code isn't correct, it needs to check the sequence numbers
;; before accepting this packet and resetting the connection. This is
;; currently only done correctly in the :ESTABLISHED state, but should
;; be done for the other states too.
;; currently only done correctly in the states: :SYN-SENT, :ESTABLISHED
;; But should be done for the other states too.
;; Remote has sent RST, aborting connection
(setf (tcp-connection-pending-error connection)
(make-condition 'connection-reset
Expand All @@ -573,38 +574,42 @@ Set to a value near 2^32 to test SND sequence number wrapping.")
;; :CLOSED should never be seen here
(ecase (tcp-connection-state connection)
(:syn-sent
;; Active open
(cond ((and (logtest flags +tcp4-flag-ack+)
(cond ((logtest flags +tcp4-flag-rst+)
(when (acceptable-ack-p connection ack)
(setf (tcp-connection-pending-error connection)
(make-condition 'connection-reset
:host (tcp-connection-remote-ip connection)
:port (tcp-connection-remote-port connection)))
(detach-tcp-connection connection)))
((and (logtest flags +tcp4-flag-ack+)
(not (acceptable-ack-p connection ack)))
;; Segment comes from an old connection
(unless *netmangler-force-local-retransmit*
(tcp4-send-packet connection ack seq nil :ack-p nil :rst-p t)))
((and (logtest flags +tcp4-flag-ack+)
(logtest flags +tcp4-flag-syn+)
(eql ack (tcp-connection-snd.nxt connection)))
;; Remote has sent SYN+ACK and waiting for ACK
;; Active open
(initial-rtt-measurement connection)
(setf (tcp-connection-state connection) :established)
(setf (tcp-connection-rcv.nxt connection) (+u32 seq 1))
(setf (tcp-connection-snd.una connection) ack)
(when (not *netmangler-force-local-retransmit*)
(tcp4-send-packet connection ack (tcp-connection-rcv.nxt connection) nil))
(setf (tcp-connection-state connection) :established
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(tcp-connection-rcv.nxt connection) (+u32 seq 1)
(tcp-connection-snd.una connection) ack)
(unless *netmangler-force-local-retransmit*
(tcp4-send-ack connection))
;; Cancel retransmit
(disarm-retransmit-timer connection)
(disarm-timeout-timer connection))
((logtest flags +tcp4-flag-syn+)
;; Simultaneous open
(setf (tcp-connection-state connection) :syn-received
(tcp-connection-rcv.nxt connection) (+u32 seq 1))
(when (not *netmangler-force-local-retransmit*)
;; TODO: Update window
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(unless *netmangler-force-local-retransmit*
(tcp4-send-packet connection ack (tcp-connection-rcv.nxt connection) nil
:ack-p t :syn-p t))
:syn-p t))
;; Cancel retransmit
(disarm-retransmit-timer connection)
(disarm-timeout-timer connection))
(t
;; Aborting connection
(tcp4-send-packet connection ack seq nil :rst-p t)
(setf (tcp-connection-pending-error connection)
(make-condition 'connection-aborted
:host (tcp-connection-remote-ip connection)
:port (tcp-connection-remote-port connection)))
(detach-tcp-connection connection))))
(disarm-timeout-timer connection))))
(:syn-received
;; Pasive open
(cond ((and (eql flags +tcp4-flag-ack+)
Expand Down Expand Up @@ -632,13 +637,9 @@ Set to a value near 2^32 to test SND sequence number wrapping.")
(remhash connection (tcp-listener-pending-connections listener))
(decf (tcp-listener-n-pending-connections listener))))))
(:established
(cond ((not (acceptable-segment-p connection packet start end))
(cond ((not (acceptable-segment-p connection seq data-length))
(when (not (logtest flags +tcp4-flag-rst+))
(tcp4-send-packet connection
(tcp-connection-snd.nxt connection)
(tcp-connection-rcv.nxt connection)
nil
:ack-p t)))
(tcp4-send-ack connection)))
((logtest flags +tcp4-flag-rst+)
(setf (tcp-connection-pending-error connection)
(make-condition 'connection-reset
Expand All @@ -652,7 +653,7 @@ Set to a value near 2^32 to test SND sequence number wrapping.")
:port (tcp-connection-remote-port connection)))
(detach-tcp-connection connection)
(tcp4-send-packet connection
(tcp-connection-snd.next connection)
(tcp-connection-snd.nxt connection)
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0 ; ???
nil
:ack-p nil
Expand Down Expand Up @@ -700,7 +701,7 @@ Set to a value near 2^32 to test SND sequence number wrapping.")
(setf (mezzano.supervisor:event-state
(tcp-connection-receive-event connection))
t)
(tcp4-send-packet connection ack (+u32 seq 1) nil :ack-p t))
(tcp4-send-packet connection ack (+u32 seq 1) nil))
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(tcp4-receive-data connection data-length end header-length packet seq start)))
((eql (tcp-connection-snd.una connection) ack)
;; TODO: slow start/duplicate ack detection/fast retransmit/etc.
Expand All @@ -722,10 +723,7 @@ Set to a value near 2^32 to test SND sequence number wrapping.")
(cond ((logtest flags +tcp4-flag-fin+)
(setf (tcp-connection-rcv.nxt connection)
(+u32 (tcp-connection-rcv.nxt connection) 1))
(tcp4-send-packet connection
(tcp-connection-snd.nxt connection)
(tcp-connection-rcv.nxt connection)
nil)
(tcp4-send-ack connection)
(if (logtest flags +tcp4-flag-ack+)
;; Remote saw our FIN and closed as well.
(detach-tcp-connection connection)
Expand All @@ -743,10 +741,7 @@ Set to a value near 2^32 to test SND sequence number wrapping.")
;; Remote has sent FIN and waiting for ACK
(setf (tcp-connection-rcv.nxt connection)
(+u32 (tcp-connection-rcv.nxt connection) 1))
(tcp4-send-packet connection
(tcp-connection-snd.nxt connection)
(tcp-connection-rcv.nxt connection)
nil)
(tcp4-send-ack connection)
(detach-tcp-connection connection))
(tcp4-receive-data connection data-length end header-length packet seq start)))
(:closing
Expand Down Expand Up @@ -787,6 +782,18 @@ Set to a value near 2^32 to test SND sequence number wrapping.")
(when errors-escape
(error c))))))

(defun tcp4-send-ack (connection)
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(tcp4-send-packet connection
(tcp-connection-snd.nxt connection)
(tcp-connection-rcv.nxt connection)
nil))

(defun challenge-ack (connection)
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(tcp4-send-packet connection
(tcp-connection-snd.nxt connection)
(tcp-connection-rcv.nxt connection)
nil))

(defun compute-ip-pseudo-header-partial-checksum (src-ip dst-ip protocol length)
(+ (logand src-ip #xFFFF)
(logand (ash src-ip -16) #xFFFF)
Expand Down