resolve node name fallback on published/node ip as fallback

src/main/java/co/elastic/support/diagnostics/commands/CheckPlatformDetails.java

@@ -268,7 +268,14 @@ public List<ProcessProfile> getNodeNetworkAndLogInfo(JsonNode nodesInfo) {
                             }
                         }
                         if (notLoopBack) {
-                            addr = addr.substring(0, addr.indexOf(":"));
+                            if (addr.startsWith("[")) {
+                                // IPv6 bracket notation: [address]:port → strip port and brackets
+                                int closingBracket = addr.indexOf("]");
+                                addr = addr.substring(1, closingBracket);
+                            } else {
+                                // IPv4: address:port → strip port
+                                addr = addr.substring(0, addr.indexOf(":"));
+                            }
                             diagNode.boundAddresses.add(addr);
                         }
                     }
@@ -350,6 +357,20 @@ private ProcessProfile findTargetNode(Set<String> localAddrs, List<ProcessProfil
             }
         }
 
+        // Fallback: boundAddresses may be empty (field absent in older ES versions, or all-loopback)
+        // or may contain wildcards (0.0.0.0) that never match a specific IP.
+        // Try matching directly against the node's reported ip and httpPublishAddr.
+        for (String localAddr : localAddrs) {
+            for (ProcessProfile node : nodeAddrs) {
+                if (localAddr.equals(node.ip) || localAddr.equals(node.httpPublishAddr)) {
+                    logger.warn(Constants.CONSOLE,
+                            "Matched node '{}' via ip/httpPublishAddr fallback (boundAddresses did not match).",
+                            node.name);
+                    return node;
+                }
+            }
+        }
+
         // If we got this far and came up empty, signal our displeasure
         logger.error("Comparison did not result in an IP or Host match. {} {}", localAddrs, nodeAddrs);
         throw new RuntimeException("Could not find the target node.");

src/test/java/co/elastic/support/diagnostics/commands/CheckPlatformDetailsTest.java

@@ -0,0 +1,136 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ *  or more contributor license agreements. Licensed under the Elastic License
+ *  2.0; you may not use this file except in compliance with the Elastic License
+ *  2.0.
+ */
+package co.elastic.support.diagnostics.commands;
+
+import co.elastic.support.diagnostics.ProcessProfile;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+import java.util.Set;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class CheckPlatformDetailsTest {
+
+    private CheckPlatformDetails checker;
+
+    @BeforeEach
+    void setUp() {
+        checker = new CheckPlatformDetails();
+    }
+
+    // -----------------------------------------------------------------------
+    // Helpers
+    // -----------------------------------------------------------------------
+
+    private ProcessProfile makeNode(String name, String ip, String httpPublishAddr,
+                                    Set<String> boundAddresses) {
+        ProcessProfile p = new ProcessProfile();
+        p.name = name;
+        p.ip = ip;
+        p.host = ip;
+        p.httpPublishAddr = httpPublishAddr;
+        p.boundAddresses = boundAddresses;
+        return p;
+    }
+
+    // -----------------------------------------------------------------------
+    // findLocalTargetNode — loopback input uses NIC-based matching
+    // -----------------------------------------------------------------------
+
+    /** When the input host is a loopback address the code must fall through
+     *  to NIC scanning; with our fallback it should still find the node via ip. */
+    @Test
+    void loopbackInput_fallsBackToNicScan_matchesViaIp() {
+        // Simulate node whose ip matches what getNetworkInterfaces() would return
+        // We can't mock the real NIC scan, so we exercise findLocalTargetNode with
+        // a non-loopback host that equals the node ip directly.
+        ProcessProfile node = makeNode("NTG-PRO-ELA-01", "172.16.1.61", "172.16.1.61",
+                new java.util.HashSet<>());
+        // Non-loopback host that equals the node ip → added to localNetworkInterfaces
+        ProcessProfile result = checker.findLocalTargetNode("172.16.1.61", List.of(node));
+        assertNotNull(result);
+        assertEquals("NTG-PRO-ELA-01", result.name);
+    }
+
+    // -----------------------------------------------------------------------
+    // findTargetNode — primary: boundAddresses match
+    // -----------------------------------------------------------------------
+
+    @Test
+    void matchViaBoundAddresses_returnsCorrectNode() {
+        ProcessProfile node1 = makeNode("node-1", "10.0.0.1", "10.0.0.1",
+                new java.util.HashSet<>(Set.of("10.0.0.1")));
+        ProcessProfile node2 = makeNode("node-2", "10.0.0.2", "10.0.0.2",
+                new java.util.HashSet<>(Set.of("10.0.0.2")));
+
+        ProcessProfile result = checker.findLocalTargetNode("10.0.0.2", List.of(node1, node2));
+        assertEquals("node-2", result.name);
+    }
+
+    // -----------------------------------------------------------------------
+    // findTargetNode — fallback: boundAddresses empty, match via node.ip
+    // -----------------------------------------------------------------------
+
+    @Test
+    void emptyBoundAddresses_matchViaIpFallback() {
+        ProcessProfile node = makeNode("NTG-PRO-ELA-01", "172.16.1.61", "172.16.1.61",
+                new java.util.HashSet<>());
+
+        ProcessProfile result = checker.findLocalTargetNode("172.16.1.61", List.of(node));
+        assertNotNull(result);
+        assertEquals("NTG-PRO-ELA-01", result.name);
+    }
+
+    @Test
+    void emptyBoundAddresses_matchViaHttpPublishAddrFallback() {
+        // ip and httpPublishAddr differ (NAT / publish_host override scenario)
+        ProcessProfile node = makeNode("NTG-PRO-ELA-01", "10.0.0.5", "172.16.1.61",
+                new java.util.HashSet<>());
+
+        // local address matches httpPublishAddr, not ip
+        ProcessProfile result = checker.findLocalTargetNode("172.16.1.61", List.of(node));
+        assertNotNull(result);
+        assertEquals("NTG-PRO-ELA-01", result.name);
+    }
+
+    // -----------------------------------------------------------------------
+    // findTargetNode — multiple nodes, only one matches (mirrors the bug report)
+    // -----------------------------------------------------------------------
+
+    @Test
+    void multipleNodes_emptyBoundAddresses_returnsCorrectOne() {
+        ProcessProfile ela01 = makeNode("NTG-PRO-ELA-01", "172.16.1.61", "172.16.1.61",
+                new java.util.HashSet<>());
+        ProcessProfile ela02 = makeNode("NTG-PRO-ELA-02", "172.16.1.62", "172.16.1.62",
+                new java.util.HashSet<>());
+        ProcessProfile ela03 = makeNode("NTG-PRO-ELA-03", "172.16.1.63", "172.16.1.63",
+                new java.util.HashSet<>());
+        ProcessProfile ela04 = makeNode("NTG-PRO-ELA-04", "172.16.1.64", "172.16.1.64",
+                new java.util.HashSet<>());
+
+        // The local machine is NTG-PRO-ELA-01 (172.16.1.61)
+        ProcessProfile result = checker.findLocalTargetNode("172.16.1.61",
+                List.of(ela01, ela02, ela03, ela04));
+        assertNotNull(result);
+        assertEquals("NTG-PRO-ELA-01", result.name);
+    }
+
+    // -----------------------------------------------------------------------
+    // findTargetNode — no match throws RuntimeException
+    // -----------------------------------------------------------------------
+
+    @Test
+    void noMatch_throwsRuntimeException() {
+        ProcessProfile node = makeNode("node-1", "10.0.0.1", "10.0.0.1",
+                new java.util.HashSet<>());
+
+        assertThrows(RuntimeException.class,
+                () -> checker.findLocalTargetNode("192.168.99.99", List.of(node)));
+    }
+}