TFO: better detection of client fast-open connections (again)

[exim.git] / src / src / ip.c

diff --git a/src/src/ip.c b/src/src/ip.c
index 266eaf41484c9f9840a155b5d7f322b6126b36d0..eb01229e6b7ec3181e6304018f780b5c799f8fd3 100644 (file)
--- a/src/src/ip.c
+++ b/src/src/ip.c
@@ -236,22 +236,26 @@ if (fastopen)
   {
   if ((rc = sendto(sock, fastopen->data, fastopen->len,
                    MSG_FASTOPEN | MSG_DONTWAIT, s_ptr, s_len)) >= 0)
+       /* seen for with-data, experimental TFO option, with-cookie case */
     {
-    DEBUG(D_transport|D_v)
-      debug_printf("TCP_FASTOPEN mode connection, with data\n");
-    tcp_out_fastopen = TRUE;
+    DEBUG(D_transport|D_v) debug_printf("TFO mode connection attempt, %s data\n",
+      fastopen->len > 0 ? "with"  : "no");
+    tcp_out_fastopen = fastopen->len > 0 ?  2 : 1;
     }
   else if (errno == EINPROGRESS)       /* expected for nonready peer */
-    {
+       /* seen for no-data, proper TFO option, both cookie-request and with-cookie cases */
+       /*  apparently no visibility of the diffference at this point */
+       /*   with netwk delay, post-conn tcp_info sees unacked 1 for R, 2 for C; code in smtp_out.c */
+       /* ? older Experimental TFO option behaviour ? */
+    {                                  /* queue unsent data */
     if (!fastopen->data)
       {
-      DEBUG(D_transport|D_v)
-       debug_printf("TCP_FASTOPEN mode connection, no data\n");
-      tcp_out_fastopen = TRUE;
+      tcp_out_fastopen = 1;    /* we tried; unknown if useful yet */
       rc = 0;
       }
     else if (  (rc = send(sock, fastopen->data, fastopen->len, 0)) < 0
-           && errno == EINPROGRESS)    /* expected for nonready peer */
+           && errno == EINPROGRESS     /* expected for nonready peer */
+           )
       rc = 0;
     }
   else if(errno == EOPNOTSUPP)