Adding a FIN message to differentiate normal TCP closing from failures

Signed-off-by: Aurelien Bouteiller <bouteill@icl.utk.edu>

opal/mca/btl/tcp/btl_tcp_endpoint.c

@@ -2,7 +2,7 @@
  * Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
  *                         University Research and Technology
  *                         Corporation.  All rights reserved.
- * Copyright (c) 2004-2017 The University of Tennessee and The University
+ * Copyright (c) 2004-2020 The University of Tennessee and The University
  *                         of Tennessee Research Foundation.  All rights
  *                         reserved.
  * Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
@@ -535,6 +535,19 @@ void mca_btl_tcp_endpoint_close(mca_btl_base_endpoint_t* btl_endpoint)
     btl_endpoint->endpoint_cache_length = 0;
 #endif  /* MCA_BTL_TCP_ENDPOINT_CACHE */
 
+    /* send a message before closing to differentiate between failures and
+     * clean disconnect during finalize */
+    if( MCA_BTL_TCP_CONNECTED == btl_endpoint->endpoint_state ) {
+        mca_btl_tcp_hdr_t fin_msg = {
+            .base.tag = 0,
+            .type = MCA_BTL_TCP_HDR_TYPE_FIN,
+            .count = 0,
+            .size = 0,
+        };
+        mca_btl_tcp_endpoint_send_blocking(btl_endpoint,
+                                           &fin_msg, sizeof(fin_msg));
+    }
+
     CLOSE_THE_SOCKET(btl_endpoint->endpoint_sd);
     btl_endpoint->endpoint_sd = -1;
     /**

opal/mca/btl/tcp/btl_tcp_frag.c

@@ -3,7 +3,7 @@
  * Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
  *                         University Research and Technology
  *                         Corporation.  All rights reserved.
- * Copyright (c) 2004-2016 The University of Tennessee and The University
+ * Copyright (c) 2004-2020 The University of Tennessee and The University
  *                         of Tennessee Research Foundation.  All rights
  *                         reserved.
  * Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
@@ -273,6 +273,10 @@ bool mca_btl_tcp_frag_recv(mca_btl_tcp_frag_t* frag, int sd)
     if(frag->iov_cnt == 0) {
         if (btl_endpoint->endpoint_nbo && frag->iov_idx == 1) MCA_BTL_TCP_HDR_NTOH(frag->hdr);
         switch(frag->hdr.type) {
+        case MCA_BTL_TCP_HDR_TYPE_FIN:
+            frag->endpoint->endpoint_state = MCA_BTL_TCP_CLOSED;
+            mca_btl_tcp_endpoint_close(frag->endpoint);
+            break;
         case MCA_BTL_TCP_HDR_TYPE_SEND:
             if(frag->iov_idx == 1 && frag->hdr.size) {
                 frag->segments[0].seg_addr.pval = frag+1;

opal/mca/btl/tcp/btl_tcp_hdr.h

@@ -2,7 +2,7 @@
  * Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
  *                         University Research and Technology
  *                         Corporation.  All rights reserved.
- * Copyright (c) 2004-2005 The University of Tennessee and The University
+ * Copyright (c) 2004-2020 The University of Tennessee and The University
  *                         of Tennessee Research Foundation.  All rights
  *                         reserved.
  * Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
@@ -33,6 +33,7 @@ BEGIN_C_DECLS
 #define MCA_BTL_TCP_HDR_TYPE_SEND 1
 #define MCA_BTL_TCP_HDR_TYPE_PUT  2
 #define MCA_BTL_TCP_HDR_TYPE_GET  3
+#define MCA_BTL_TCP_HDR_TYPE_FIN  4
 
 struct mca_btl_tcp_hdr_t {
     mca_btl_base_header_t base;