Reorganize the Connection types such that the defined types no longer expose
the lower-level functions SendFrame and CreateFrame. These methods are still
exported on the underlying Connection type, and thus can be accessed via a
type-cast. In future, defined types should have one or more type-safe versions
of the send() method on Connection, e.g. UDPIPv4 has Send() which allows the UDP
header to be overridden and SendIP() which allows both the IPv4 and UDP headers
to be modified.
testbench.Connection gets a SendFrameStateless method which sends frames
without updating the state of any of the layers. This should be used when
sending out-of-band control messages such as ICMP messages, as using the
normal Send method can result in errors when attempting to update the TCP
state using an ICMP packet.
Also remove the localAddr field of testbench.Connection and instead compute
it on the fly as needed for UDPIPv4 and TCPIPv4.
PiperOrigin-RevId: 315969714
- Always split segments larger than MSS.
Currently, we base the segment split decision as a function of the
send congestion window and MSS, which could be greater than the MSS
advertised by remote.
- While splitting segments, ensure the PSH flag is reset when there
are segments that are queued to be sent.
- With TCP_CORK, hold up segments up until MSS. Fix a bug in computing
available send space before attempting to coalesce segments.
Fixes#2832
PiperOrigin-RevId: 314802928
TCP, in CLOSE-WAIT state, MUST return ACK with proper SEQ and ACK numbers after
recv a seg with OTW SEQ or unacc ACK number, and remain in same state. If the
connection is in a synchronized state, any unacceptable segment (out of window
sequence number or unacceptable acknowledgment number) must elicit only an empty
acknowledgment segment containing the current send-sequence number and an
acknowledgment indicating the next sequence number expected to be received, and
the connection remains in the same state.
PiperOrigin-RevId: 306897984
Rather than have a struct for the state of each type of connection, such as
TCP/IPv4, UDP/IPv4, TCP/IPv6, etc, have a state for each layer, such as UDP,
TCP, IPv4, IPv6. Those states can be composed into connections.
Tested:
Existing unit tests still pass/fail as expected.
PiperOrigin-RevId: 306703180
Add Sniffer.Drain() which drains the socket's receive buffer by temporarily
setting the socket to non-blocking, and receiving in a loop until EINTR,
EWOULDBLOCK or EAGAIN. This method should be used when long periods of time
elapses without receiving on the socket, because uninteresting packets may have
piled up in the receive buffer, filling it up and causing packets critical to
test operation to be dropped.
PiperOrigin-RevId: 306380480
RFC 1122 Section 3.7: A sending TCP MUST be robust against window shrinking,
which may cause the "useable window" to become negative.
PiperOrigin-RevId: 305377072
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Mithun Iyer
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