Fix handling of unacceptable ACKs during close.

On receiving an ACK with unacceptable ACK number, in a closing state,
TCP, needs to reply back with an ACK with correct seq and ack numbers and
remain in same state. This change is as per RFC793 page 37, but with a
difference that it does not apply to ESTABLISHED state, just as in Linux.
Also add more tests to check for OTW sequence number and unacceptable
ack numbers in these states.

Fixes #3785

PiperOrigin-RevId: 329616283

1 files changed, 11 insertions, 0 deletions

diff --git a/test/packetimpact/proto/posix_server.proto b/test/packetimpact/proto/posix_server.proto
index ccd20b10d..f32ed54ef 100644
--- a/test/packetimpact/proto/posix_server.proto
+++ b/test/packetimpact/proto/posix_server.proto
@@ -188,6 +188,15 @@ message SocketResponse {
   int32 errno_ = 2;  // "errno" may fail to compile in c++.
 }
 
+message ShutdownRequest {
+  int32 fd = 1;
+  int32 how = 2;
+}
+
+message ShutdownResponse {
+  int32 errno_ = 1;  // "errno" may fail to compile in c++.
+}
+
 message RecvRequest {
   int32 sockfd = 1;
   int32 len = 2;
@@ -225,6 +234,8 @@ service Posix {
   rpc SetSockOpt(SetSockOptRequest) returns (SetSockOptResponse);
   // Call socket() on the DUT.
   rpc Socket(SocketRequest) returns (SocketResponse);
+  // Call shutdown() on the DUT.
+  rpc Shutdown(ShutdownRequest) returns (ShutdownResponse);
   // Call recv() on the DUT.
   rpc Recv(RecvRequest) returns (RecvResponse);
 }