From dfbddf368eccd05cb2608a89c9252b2d103ead56 Mon Sep 17 00:00:00 2001
From: Arne Juul <arnej@yahooinc.com>
Date: Fri, 26 Aug 2022 09:43:18 +0000
Subject: add FindOurHostname()

---
 client/go/vespa/detect_hostname.go      | 108 ++++++++++++++++++++++++++++++++
 client/go/vespa/detect_hostname_test.go |  27 ++++++++
 2 files changed, 135 insertions(+)
 create mode 100644 client/go/vespa/detect_hostname.go
 create mode 100644 client/go/vespa/detect_hostname_test.go

(limited to 'client')

diff --git a/client/go/vespa/detect_hostname.go b/client/go/vespa/detect_hostname.go
new file mode 100644
index 00000000000..2cd1e44db1f
--- /dev/null
+++ b/client/go/vespa/detect_hostname.go
@@ -0,0 +1,108 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+// Author: arnej
+
+package vespa
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"strings"
+)
+
+// detect if this host is IPv6-only, in which case we want to pass
+// the flag "-Djava.net.preferIPv6Addresses=true" to any java command
+
+func HasOnlyIpV6() bool {
+	hostname, err := os.Hostname()
+	hostname, err = FindOurHostname(hostname)
+	if hostname == "" || err != nil {
+		return false
+	}
+	foundV4 := false
+	foundV6 := false
+	ipAddrs, err := net.LookupIP(hostname)
+	if err != nil {
+		return false
+	}
+	for _, addr := range ipAddrs {
+		switch {
+		case addr.IsLoopback():
+			// skip
+		case addr.To4() != nil:
+			foundV4 = true
+		case addr.To16() != nil:
+			foundV6 = true
+		}
+	}
+	return foundV6 && !foundV4
+}
+
+func FindOurHostname(name string) (string, error) {
+	env := os.Getenv("VESPA_HOSTNAME")
+	if env != "" {
+		// assumes: env var is already validated and OK
+		fmt.Fprintln(os.Stderr, "from env:", env)
+		return env, nil
+	}
+	ifAddrs, _ := net.InterfaceAddrs()
+	fmt.Fprintln(os.Stderr, "interface addrs:", ifAddrs)
+	var checkIsMine = func(addr string) bool {
+		if len(ifAddrs) == 0 {
+			// no validation possible, assume OK
+			return true
+		}
+		for _, ifAddr := range ifAddrs {
+			if ipnet, ok := ifAddr.(*net.IPNet); ok {
+				if ipnet.IP.String() == addr {
+					return true
+				}
+			}
+		}
+		return false
+	}
+	if name != "" {
+		ipAddrs, _ := net.LookupIP(name)
+		fmt.Fprintln(os.Stderr, "LookupIP", name, "->", ipAddrs)
+		for _, addr := range ipAddrs {
+			switch {
+			case addr.IsLoopback():
+				// skip
+			case addr.To4() != nil || addr.To16() != nil:
+				if checkIsMine(addr.String()) {
+					reverseNames, _ := net.LookupAddr(addr.String())
+					for _, reverse := range reverseNames {
+						if strings.HasPrefix(reverse, name) {
+							fmt.Fprintln(os.Stderr, "hostname", name, "->", addr, "-> ", reverse)
+							return reverse, nil
+						}
+					}
+					if len(reverseNames) > 0 {
+						reverse := reverseNames[0]
+						fmt.Fprintln(os.Stderr, "hostname", name, "->", addr, "-> ", reverse)
+						return reverse, nil
+					}
+				}
+			}
+		}
+	}
+	for _, ifAddr := range ifAddrs {
+		if ipnet, ok := ifAddr.(*net.IPNet); ok {
+			ip := ipnet.IP
+			fmt.Fprintln(os.Stderr, "converted IP", ifAddr, "->", ip)
+			if ip == nil || ip.IsLoopback() {
+				continue
+			}
+			reverseNames, _ := net.LookupAddr(ip.String())
+			if len(reverseNames) > 0 {
+				reverse := reverseNames[0]
+				fmt.Fprintln(os.Stderr, "interface", ifAddr, "->", reverse)
+				return reverse, nil
+			}
+		}
+	}
+	if name != "" {
+		return name, fmt.Errorf("unvalidated hostname '%s'", name)
+	}
+	return "localhost", fmt.Errorf("fallback to localhost, os.Hostname '%s'", name)
+}
diff --git a/client/go/vespa/detect_hostname_test.go b/client/go/vespa/detect_hostname_test.go
new file mode 100644
index 00000000000..bb61e157b26
--- /dev/null
+++ b/client/go/vespa/detect_hostname_test.go
@@ -0,0 +1,27 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package vespa
+
+import (
+	"fmt"
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDetectHostname(t *testing.T) {
+	os.Setenv("VESPA_HOSTNAME", "foo.bar")
+	got, err := FindOurHostname("bar.foo")
+	assert.Equal(t, "foo.bar", got)
+	os.Unsetenv("VESPA_HOSTNAME")
+	got, err = FindOurHostname("bar.foo.123")
+	fmt.Fprintln(os.Stderr, "FindOurHostname() returns: ", got, "with error:", err)
+	assert.NotEqual(t, "", got)
+	parts := strings.Split(got, ".")
+	if len(parts) > 1 {
+		expanded, err2 := FindOurHostname(parts[0])
+		fmt.Fprintln(os.Stderr, "FindOurHostname(", parts[0], ") returns: ", expanded, "with error:", err2)
+		assert.Equal(t, got, expanded)
+	}
+}
-- 
cgit v1.2.3