From 996a98d33f790a1e6af927c02318649feec6061b Mon Sep 17 00:00:00 2001
From: Jeremy Harris <jgh146exb@wizmail.org>
Date: Thu, 31 Dec 2020 21:52:02 +0000
Subject: [PATCH 1/1] TFO: better observability (slightly) on FreeBSD

---
 src/src/smtp_out.c                   | 32 +++++++++++++++++++---------
 test/runtest                         |  2 +-
 test/scripts/1990-TCP-Fast-Open/1990 | 15 +++++++++++++
 3 files changed, 38 insertions(+), 11 deletions(-)

diff --git a/src/src/smtp_out.c b/src/src/smtp_out.c
index 0bf619795..bb7a0e3b3 100644
--- a/src/src/smtp_out.c
+++ b/src/src/smtp_out.c
@@ -159,20 +159,32 @@ tfo_out_check(int sock)
 {
 # ifdef __FreeBSD__
 struct tcp_info tinfo;
-int val;
-socklen_t len = sizeof(val);
+socklen_t len = sizeof(tinfo);
 
-/* The observability as of 12.1 is not useful as a client, only telling us that
-a TFO option was used on SYN.  It could have been a TFO-R, or ignored by the
-server. */
+/* A getsockopt TCP_FASTOPEN unfortunately returns "was-used" for a TFO/R as
+well as a TFO/C.  Use what we can of the Linux hack below; reliability issues ditto. */
+switch (tcp_out_fastopen)
+  {
+  case TFO_ATTEMPTED_NODATA:
+    if (  getsockopt(sock, IPPROTO_TCP, TCP_INFO, &tinfo, &len) == 0
+       && tinfo.tcpi_state == TCPS_SYN_SENT
+       && tinfo.__tcpi_unacked > 0
+       )
+      {
+      DEBUG(D_transport|D_v)
+       debug_printf("TCP_FASTOPEN tcpi_unacked %d\n", tinfo.__tcpi_unacked);
+      tcp_out_fastopen = TFO_USED_NODATA;
+      }
+    break;
+  /*
+  case TFO_ATTEMPTED_DATA:
+  case TFO_ATTEMPTED_DATA:
+       if (tinfo.tcpi_options & TCPI_OPT_SYN_DATA)   XXX no equvalent as of 12.2
+  */
+  }
 
-/*
-if (tcp_out_fastopen == TFO_ATTEMPTED_NODATA || tcp_out_fastopen == TFO_ATTEMPTED_DATA)
-  if (getsockopt(sock, IPPROTO_TCP, TCP_FASTOPEN, &val, &len) == 0 && val != 0) {}
-*/
 switch (tcp_out_fastopen)
   {
-  case TFO_ATTEMPTED_NODATA:	tcp_out_fastopen = TFO_USED_NODATA; break;
   case TFO_ATTEMPTED_DATA:	tcp_out_fastopen = TFO_USED_DATA; break;
   default: break; /* compiler quietening */
   }
diff --git a/test/runtest b/test/runtest
index b5ace4ee3..1e604e1cd 100755
--- a/test/runtest
+++ b/test/runtest
@@ -3112,7 +3112,7 @@ if (defined $parm_trusted_config_list)
   open(TCL, $parm_trusted_config_list) or die "Can't open $parm_trusted_config_list: $!\n";
   my $test_config = getcwd() . '/test-config';
   die "Can't find '$test_config' in TRUSTED_CONFIG_LIST $parm_trusted_config_list."
-  if not grep { /^\Q$test_config\E$/ } <TCL>;
+    if not grep { /^\Q$test_config\E$/ } <TCL>;
   }
 else
   {
diff --git a/test/scripts/1990-TCP-Fast-Open/1990 b/test/scripts/1990-TCP-Fast-Open/1990
index 80059e685..d2c7b75f9 100644
--- a/test/scripts/1990-TCP-Fast-Open/1990
+++ b/test/scripts/1990-TCP-Fast-Open/1990
@@ -27,6 +27,14 @@
 # 'net.inet.tcp.fastopen.server_enable=1' in /etc/sysctl.conf
 # Seems to always claim TFO used by transport, if tried.
 #
+# FreeBSD: tried this setup, but we only get the banner captured 100ms after 3rd-ack:
+# #kenv net.inet.ip.fw.default_to_accept=1
+# #kldload ipfw dummynet
+# #ipfw add 00097 pipe 1 ip from 127.0.0.1 to 127.0.0.1
+# #ipfw pipe 1 config delay 50ms
+# Also, the VM managed to lose the ipv4 & 6 addrs on its main interface
+# after a while - so not usable in production
+#
 sudo perl
 system ("tc qdisc add dev lo root netem delay 50ms");
 ****
@@ -50,7 +58,14 @@ system ("[ -e /proc/sys/net/ipv4/tcp_fastopen_blackhole_timeout_sec ] && echo 0
 #
 # First clear any previously-obtained cookie:
 sudo perl
+open(INFO, "-|", "/usr/bin/uname -s");
+$_ = <INFO>;
+if (/^FreeBSD/) {
+system("sysctl net.inet.tcp.fastopen.client_enable=0"); system("sysctl net.inet.tcp.fastopen.client_enable=1");
+} else {
 system ("ip tcp_metrics delete 127.0.0.1");
+}
+
 ****
 #
 #
-- 
2.30.2