smtp transport: poll for trailing data to drain before close

[exim.git] / src / src / transports / smtp.c

diff --git a/src/src/transports/smtp.c b/src/src/transports/smtp.c
index c64bb7010cffa763156dd79f591db236172aeb96..721056f278978bf5aa30b3471e53ff33d032e855 100644 (file)
--- a/src/src/transports/smtp.c
+++ b/src/src/transports/smtp.c
@@ -4349,6 +4349,7 @@ else
              "%s: %s", sx->buffer, strerror(errno));
          }
        else if (addr->transport_return == DEFER)
+         /*XXX magic value -2 ? maybe host+message ? */
          retry_add_item(addr, addr->address_retry_key, -2);
       }
 #endif
@@ -4809,8 +4810,11 @@ if (sx->send_quit || tcw_done && !tcw)
     sx->cctx.tls_ctx = NULL;
     }
 #endif
-  millisleep(20);
-  if (fcntl(sx->cctx.sock, F_SETFL, O_NONBLOCK) == 0)
+
+  /* Drain any trailing data from the socket before close, to avoid sending a RST */
+
+  if (  poll_one_fd(sx->cctx.sock, POLLIN, 20) != 0            /* 20ms */
+     && fcntl(sx->cctx.sock, F_SETFL, O_NONBLOCK) == 0)
     for (int i = 16, n;                                                /* drain socket */
         (n = read(sx->cctx.sock, sx->inbuffer, sizeof(sx->inbuffer))) > 0 && i > 0;
         i--) HDEBUG(D_transport|D_acl|D_v)