Fix common_ipv6 test failures on runners without IPv6 support (#7732)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: achamayou <4016369+achamayou@users.noreply.github.com>

Author: Copilot

src/node/node_state.h

@@ -2184,8 +2184,7 @@ namespace ccf
       // numeric, but at least the final component (TLD) must not be
       // all-numeric. So this distinguishes "1.2.3.4" (an IP address) from
       // "1.2.3.c4m" (a DNS name). "1.2.3." is invalid for either, and will
-      // throw. Attempts to handle IPv6 by also splitting on ':', but this is
-      // untested.
+      // throw. Handles IPv6 by splitting on ':' after splitting on '.'.
       const auto final_component =
         ccf::nonstd::split(ccf::nonstd::split(hostname, ".").back(), ":")
           .back();
@@ -2216,6 +2215,11 @@ namespace ccf
       for (const auto& [_, interface] : config.network.rpc_interfaces)
       {
         auto host = split_net_address(interface.published_address).first;
+        // Strip brackets from IPv6 addresses (e.g. "[::1]" -> "::1")
+        if (host.size() >= 2 && host.front() == '[' && host.back() == ']')
+        {
+          host = host.substr(1, host.size() - 2);
+        }
         sans.push_back({host, is_ip(host)});
       }
       return sans;

tests/e2e_common_endpoints.py

@@ -1,9 +1,11 @@
 # Copyright (c) Microsoft Corporation. All rights reserved.
 # Licensed under the Apache 2.0 License.
 import infra.network
+import infra.interfaces
 from ccf.ledger import NodeStatus
 import http
 import random
+import socket
 import suite.test_requirements as reqs
 
 
@@ -341,6 +343,15 @@ def run(args):
 
 
 def run_ipv6(args):
+    # Check if IPv6 loopback is available before attempting to start nodes.
+    # Some CI environments disable IPv6, in which case this test is skipped.
+    try:
+        with socket.socket(socket.AF_INET6, socket.SOCK_STREAM) as s:
+            s.bind(("::1", 0))
+    except (OSError, socket.error):
+        LOG.warning("IPv6 loopback (::1) is not available, skipping IPv6 test")
+        return
+
     # Set each RPC interface host to the IPv6 loopback address directly,
     # so the setting is isolated to this test (no environment variable).
     # Ports are dynamically assigned, so sharing ::1 across nodes is fine.