btl/tcp: roll back parts of 40afd525f8

Some of the show_help() messages that were added in 40afd525f8 were
really normal / expected behavior (e.g., if 2 peers connect in the TCP
BTL more-or-less simultaneously, one of them will drop the connection
-- no need to show_help() about this; it's expected behavior).  Roll
back these messages to be opal_output_verbose() kinds of messages.

Signed-off-by: Jeff Squyres <jsquyres@cisco.com>

opal/mca/btl/tcp/btl_tcp_component.c

@@ -1398,45 +1398,36 @@ static void mca_btl_tcp_component_recv_handler(int sd, short flags, void* user)
     OBJ_RELEASE(event);
     retval = mca_btl_tcp_recv_blocking(sd, (void *)&hs_msg, sizeof(hs_msg));
 
-    /* An unknown process attempted to connect to Open MPI via TCP.
-     * Open MPI uses a "magic" string to trivially verify that the connecting
-     * process is a fellow Open MPI process.  An MPI process accepted a TCP
-     * connection but did not receive the correct magic string.  This might
-     * indicate an Open MPI version mismatch between different MPI processes
-     * in the same job, or it may indicate that some other agent is
-     * mistakenly attempting to connect to Open MPI's TCP listening sockets.
+    /* If we get a zero-length message back, it's likely that we
+       connected to Open MPI peer process X simultaneously, and the
+       peer closed its connection to us (in favor of our connection to
+       them).  This is not an error -- just close it and move on.
 
-     * This attempted connection will be ignored; your MPI job may or may not
-     * continue properly.
-     */
-    if (sizeof(hs_msg) != retval) {
+       Similarly, if we get less than sizeof(hs_msg) bytes, it
+       probably wasn't an Open MPI peer.  But we don't really care,
+       because the peer closed the socket.  So just close it and move
+       on. */
+    if (retval < sizeof(hs_msg)) {
          const char *peer = opal_fd_get_peer_name(sd);
-         opal_show_help("help-mpi-btl-tcp.txt",
-                        "did not receive full magic id string",
-                        true,
-                        opal_process_info.nodename,
-                        getpid(),
-                        opal_version_string,
-                        peer);
+         opal_output_verbose(20, opal_btl_base_framework.framework_output,
+                             "Peer %s closed socket without sending BTL TCP magic ID handshake (we received %d bytes out of the expected %d) -- closing/ignoring this connection",
+                             peer, (int) retval, (int) sizeof(hs_msg));
          free((char*) peer);
-
-         /* The other side probably isn't OMPI, so just hang up */
          CLOSE_THE_SOCKET(sd);
          return;
     }
 
+    /* Open MPI uses a "magic" string to trivially verify that the
+       connecting process is a fellow Open MPI process.  See if we got
+       the correct magic string. */
     guid = hs_msg.guid;
     if (0 != strncmp(hs_msg.magic_id, mca_btl_tcp_magic_id_string, len)) {
          const char *peer = opal_fd_get_peer_name(sd);
-         opal_show_help("help-mpi-btl-tcp.txt",
-                        "received incorrect magic id string",
-                        true,
-                        opal_process_info.nodename,
-                        getpid(),
-                        opal_version_string,
+         opal_output_verbose(20, opal_btl_base_framework.framework_output,
+                             "Peer %s send us an incorrect Open MPI magic ID string (i.e., this was not a connection from the same version of Open MPI; expected \"%s\", received \"%s\")",
                              peer,
-                        hs_msg.magic_id,
-                        mca_btl_tcp_magic_id_string);
+                             mca_btl_tcp_magic_id_string,
+                             hs_msg.magic_id);
          free((char*) peer);
 
         /* The other side probably isn't OMPI, so just hang up */

opal/mca/btl/tcp/help-mpi-btl-tcp.txt

@@ -1,6 +1,6 @@
 # -*- text -*-
 #
-# Copyright (c) 2009-2017 Cisco Systems, Inc.  All rights reserved
+# Copyright (c) 2009-2018 Cisco Systems, Inc.  All rights reserved
 # Copyright (c) 2015-2016 The University of Tennessee and The University
 #                         of Tennessee Research Foundation.  All rights
 #                         reserved.
@@ -167,43 +167,3 @@ Your Open MPI job may now fail.
   PID:        %d
   Message:    %s
   Error:      %s (%d)
-#
-[did not receive full magic id string]
-The TCP BTL received an inbound socket connection from an unidentified
-peer.  This typically means one of two things:
-
-1. A non-Open MPI process tried to connect to this Open MPI process.
-2. An Open MPI process compiled against a different version of Open
-   MPI tried to connect to this Open MPI process.
-
-Open MPI only supports running exactly the same version between all
-processes in a single job.
-
-This may cause unpredictable behavior, and may end up aborting your
-job.
-
-  Local host:             %s
-  Local PID:              %d
-  Local Open MPI version: %s
-  Peer IP address:        %s
-#
-[received incorrect magic id string]
-The TCP BTL received an inbound socket connection from a peer that did
-not identify itself correctly as an Open MPI process. This typically
-means one of two things:
-
-1. A non-Open MPI process tried to connect to this Open MPI process.
-2. An Open MPI process compiled against a different version of Open
-   MPI tried to connect to this Open MPI process.
-
-Open MPI only supports running exactly the same version between all
-processes in a single job.
-
-This may cause unpredictable behavior, and may end up hanging or
-aborting your job.
-
-  Local host:             %s
-  Local PID:              %d
-  Local Open MPI version: %s
-  Peer IP address:        %s
-  Peer identifier:        %s (expected %s)