From a2c0637129f0c642a4d55df297bb353243ca7a49 Mon Sep 17 00:00:00 2001 From: Florin Coras Date: Thu, 29 Aug 2019 18:33:24 -0700 Subject: [PATCH] tcp: track zero rwnd errors Type: feature Distinguish between rcv window errors and errors after we advertised a zero rcv window, i.e., potential window probes. Change-Id: I6cb453c7aaae456c0a05a8328cfaa55eaca10bf7 Signed-off-by: Florin Coras (cherry picked from commit a495a3ea146a8484dac9f6b594fb2b044437c7a4) --- src/vnet/tcp/tcp_error.def | 3 ++- src/vnet/tcp/tcp_input.c | 7 +++++++ 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/src/vnet/tcp/tcp_error.def b/src/vnet/tcp/tcp_error.def index 7dbe952e104..5acc576e3cb 100644 --- a/src/vnet/tcp/tcp_error.def +++ b/src/vnet/tcp/tcp_error.def @@ -48,4 +48,5 @@ tcp_error (OPTIONS, "Could not parse options") tcp_error (PAWS, "PAWS check failed") tcp_error (RCV_WND, "Segment not in receive window") tcp_error (FIN_RCVD, "FINs received") -tcp_error (LINK_LOCAL_RW, "No rewrite for link local connection") \ No newline at end of file +tcp_error (LINK_LOCAL_RW, "No rewrite for link local connection") +tcp_error (ZERO_RWND, "Zero receive window") \ No newline at end of file diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c index 0b1ac73209b..45a40a276b0 100755 --- a/src/vnet/tcp/tcp_input.c +++ b/src/vnet/tcp/tcp_input.c @@ -365,6 +365,13 @@ tcp_segment_validate (tcp_worker_ctx_t * wrk, tcp_connection_t * tc0, *error0 = TCP_ERROR_RCV_WND; + /* If we advertised a zero rcv_wnd and the segment is in the past or the + * next one that we expect, it is probably a window probe */ + if ((tc0->flags & TCP_CONN_ZERO_RWND_SENT) + && seq_lt (vnet_buffer (b0)->tcp.seq_end, + tc0->rcv_las + tc0->rcv_opts.mss)) + *error0 = TCP_ERROR_ZERO_RWND; + tc0->errors.below_data_wnd += seq_lt (vnet_buffer (b0)->tcp.seq_end, tc0->rcv_las);