From cd21ba0a7105268015948b39453818a1ae0284e7 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@tailscale.com>
Date: Mon, 27 Jul 2020 21:14:28 -0700
Subject: [PATCH] tailcfg, control/controlclient: add GoArch, populate
 OSVersion on Linux

---
 control/controlclient/controlclient_test.go |  7 ++
 control/controlclient/direct.go             |  9 +++
 control/controlclient/hostinfo_linux.go     | 87 +++++++++++++++++++++
 tailcfg/tailcfg.go                          |  1 +
 tailcfg/tailcfg_test.go                     |  2 +-
 5 files changed, 105 insertions(+), 1 deletion(-)
 create mode 100644 control/controlclient/hostinfo_linux.go

diff --git a/control/controlclient/controlclient_test.go b/control/controlclient/controlclient_test.go
index 7ea6c3986..25ad8fd42 100644
--- a/control/controlclient/controlclient_test.go
+++ b/control/controlclient/controlclient_test.go
@@ -70,3 +70,10 @@ func TestStatusEqual(t *testing.T) {
 		}
 	}
 }
+
+func TestOSVersion(t *testing.T) {
+	if osVersion == nil {
+		t.Skip("not available for OS")
+	}
+	t.Logf("Got: %#q", osVersion())
+}
diff --git a/control/controlclient/direct.go b/control/controlclient/direct.go
index 1cad02c54..e71882ba2 100644
--- a/control/controlclient/direct.go
+++ b/control/controlclient/direct.go
@@ -19,6 +19,7 @@ import (
 	"net/url"
 	"os"
 	"reflect"
+	"runtime"
 	"strconv"
 	"strings"
 	"sync"
@@ -165,12 +166,20 @@ func NewDirect(opts Options) (*Direct, error) {
 	return c, nil
 }
 
+var osVersion func() string // non-nil on some platforms
+
 func NewHostinfo() *tailcfg.Hostinfo {
 	hostname, _ := os.Hostname()
+	var osv string
+	if osVersion != nil {
+		osv = osVersion()
+	}
 	return &tailcfg.Hostinfo{
 		IPNVersion: version.LONG,
 		Hostname:   hostname,
 		OS:         version.OS(),
+		OSVersion:  osv,
+		GoArch:     runtime.GOARCH,
 	}
 }
 
diff --git a/control/controlclient/hostinfo_linux.go b/control/controlclient/hostinfo_linux.go
new file mode 100644
index 000000000..227098d25
--- /dev/null
+++ b/control/controlclient/hostinfo_linux.go
@@ -0,0 +1,87 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build linux,!android
+
+package controlclient
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"strings"
+	"syscall"
+
+	"go4.org/mem"
+	"tailscale.com/util/lineread"
+)
+
+func init() {
+	osVersion = osVersionLinux
+}
+
+func osVersionLinux() string {
+	m := map[string]string{}
+	lineread.File("/etc/os-release", func(line []byte) error {
+		eq := bytes.IndexByte(line, '=')
+		if eq == -1 {
+			return nil
+		}
+		k, v := string(line[:eq]), strings.Trim(string(line[eq+1:]), `"`)
+		m[k] = v
+		return nil
+	})
+
+	var un syscall.Utsname
+	syscall.Uname(&un)
+
+	var attrBuf strings.Builder
+	attrBuf.WriteString("; kernel=")
+	for _, b := range un.Release {
+		if b == 0 {
+			break
+		}
+		attrBuf.WriteByte(byte(b))
+	}
+	if inContainer() {
+		attrBuf.WriteString("; container")
+	}
+	attr := attrBuf.String()
+
+	id := m["ID"]
+
+	switch id {
+	case "debian":
+		slurp, _ := ioutil.ReadFile("/etc/debian_version")
+		return fmt.Sprintf("Debian %s (%s)%s", bytes.TrimSpace(slurp), m["VERSION_CODENAME"], attr)
+	case "ubuntu":
+		return fmt.Sprintf("Ubuntu %s%s", m["VERSION"], attr)
+	case "", "centos": // CentOS 6 has no /etc/os-release, so its id is ""
+		if cr, _ := ioutil.ReadFile("/etc/centos-release"); len(cr) > 0 { // "CentOS release 6.10 (Final)
+			return fmt.Sprintf("%s%s", bytes.TrimSpace(cr), attr)
+		}
+		fallthrough
+	case "fedora", "rhel", "alpine":
+		// Their PRETTY_NAME is fine as-is for all versions I tested.
+		fallthrough
+	default:
+		if v := m["PRETTY_NAME"]; v != "" {
+			return fmt.Sprintf("%s%s", v, attr)
+		}
+	}
+	return fmt.Sprintf("Other%s", attr)
+}
+
+func inContainer() (ret bool) {
+	lineread.File("/proc/1/cgroup", func(line []byte) error {
+		if mem.Contains(mem.B(line), mem.S("/docker/")) ||
+			mem.Contains(mem.B(line), mem.S("/lxc/")) {
+			ret = true
+			return io.EOF // arbitrary non-nil error to stop loop
+		}
+		return nil
+	})
+	return
+}
diff --git a/tailcfg/tailcfg.go b/tailcfg/tailcfg.go
index 912005a6c..e9ca209c2 100644
--- a/tailcfg/tailcfg.go
+++ b/tailcfg/tailcfg.go
@@ -260,6 +260,7 @@ type Hostinfo struct {
 	OSVersion     string       // operating system version, with optional distro prefix ("Debian 10.4", "Windows 10 Pro 10.0.19041")
 	DeviceModel   string       // mobile phone model ("Pixel 3a", "iPhone 11 Pro")
 	Hostname      string       // name of the host the client runs on
+	GoArch        string       // the host's GOARCH value (of the running binary)
 	RoutableIPs   []wgcfg.CIDR `json:",omitempty"` // set of IP ranges this client can route
 	RequestTags   []string     `json:",omitempty"` // set of ACL tags this node wants to claim
 	Services      []Service    `json:",omitempty"` // services advertised by this machine
diff --git a/tailcfg/tailcfg_test.go b/tailcfg/tailcfg_test.go
index 1ed974f98..435fd4620 100644
--- a/tailcfg/tailcfg_test.go
+++ b/tailcfg/tailcfg_test.go
@@ -24,7 +24,7 @@ func fieldsOf(t reflect.Type) (fields []string) {
 func TestHostinfoEqual(t *testing.T) {
 	hiHandles := []string{
 		"IPNVersion", "FrontendLogID", "BackendLogID", "OS", "OSVersion",
-		"DeviceModel", "Hostname", "RoutableIPs", "RequestTags", "Services",
+		"DeviceModel", "Hostname", "GoArch", "RoutableIPs", "RequestTags", "Services",
 		"NetInfo",
 	}
 	if have := fieldsOf(reflect.TypeOf(Hostinfo{})); !reflect.DeepEqual(have, hiHandles) {