From 0a42b0a72666c46846b8aa5a70c9843540d80fd2 Mon Sep 17 00:00:00 2001
From: Elias Naur <mail@eliasnaur.com>
Date: Fri, 24 Jul 2020 23:05:04 +0200
Subject: [PATCH] ipn: add OSVersion, DeviceModel fields to Prefs and propagate
 to Hostinfos

Needed for Android.

Signed-off-by: Elias Naur <mail@eliasnaur.com>
---
 ipn/local.go      | 20 ++++++++++++++------
 ipn/prefs.go      |  6 ++++++
 ipn/prefs_test.go |  2 +-
 3 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/ipn/local.go b/ipn/local.go
index d4868405b..9b5087b1b 100644
--- a/ipn/local.go
+++ b/ipn/local.go
@@ -353,9 +353,7 @@ func (b *LocalBackend) Start(opts Options) error {
 	b.serverURL = b.prefs.ControlURL
 	hostinfo.RoutableIPs = append(hostinfo.RoutableIPs, b.prefs.AdvertiseRoutes...)
 	hostinfo.RequestTags = append(hostinfo.RequestTags, b.prefs.AdvertiseTags...)
-	if b.prefs.Hostname != "" {
-		hostinfo.Hostname = b.prefs.Hostname
-	}
+	applyPrefsToHostinfo(hostinfo, b.prefs)
 
 	b.notify = opts.Notify
 	b.netMap = nil
@@ -734,9 +732,7 @@ func (b *LocalBackend) SetPrefs(new *Prefs) {
 	oldHi := b.hostinfo
 	newHi := oldHi.Clone()
 	newHi.RoutableIPs = append([]wgcfg.CIDR(nil), b.prefs.AdvertiseRoutes...)
-	if h := new.Hostname; h != "" {
-		newHi.Hostname = h
-	}
+	applyPrefsToHostinfo(newHi, new)
 	b.hostinfo = newHi
 	hostInfoChanged := !oldHi.Equal(newHi)
 	b.mu.Unlock()
@@ -943,6 +939,18 @@ func wgCIDRToNetaddr(cidrs []wgcfg.CIDR) (ret []netaddr.IPPrefix) {
 	return ret
 }
 
+func applyPrefsToHostinfo(hi *tailcfg.Hostinfo, prefs *Prefs) {
+	if h := prefs.Hostname; h != "" {
+		hi.Hostname = h
+	}
+	if v := prefs.OSVersion; v != "" {
+		hi.OSVersion = v
+	}
+	if m := prefs.DeviceModel; m != "" {
+		hi.DeviceModel = m
+	}
+}
+
 // enterState transitions the backend into newState, updating internal
 // state and propagating events out as needed.
 //
diff --git a/ipn/prefs.go b/ipn/prefs.go
index c10ffbdba..50759e1bd 100644
--- a/ipn/prefs.go
+++ b/ipn/prefs.go
@@ -54,6 +54,10 @@ type Prefs struct {
 	// Hostname is the hostname to use for identifying the node. If
 	// not set, os.Hostname is used.
 	Hostname string
+	// OSVersion overrides tailcfg.Hostinfo's OSVersion.
+	OSVersion string
+	// DeviceModel overrides tailcfg.Hostinfo's DeviceModel.
+	DeviceModel string
 
 	// NotepadURLs is a debugging setting that opens OAuth URLs in
 	// notepad.exe on Windows, rather than loading them in a browser.
@@ -138,6 +142,8 @@ func (p *Prefs) Equals(p2 *Prefs) bool {
 		p.NoSNAT == p2.NoSNAT &&
 		p.NetfilterMode == p2.NetfilterMode &&
 		p.Hostname == p2.Hostname &&
+		p.OSVersion == p2.OSVersion &&
+		p.DeviceModel == p2.DeviceModel &&
 		compareIPNets(p.AdvertiseRoutes, p2.AdvertiseRoutes) &&
 		compareStrings(p.AdvertiseTags, p2.AdvertiseTags) &&
 		p.Persist.Equals(p2.Persist)
diff --git a/ipn/prefs_test.go b/ipn/prefs_test.go
index c869cfd4d..4f75095dc 100644
--- a/ipn/prefs_test.go
+++ b/ipn/prefs_test.go
@@ -24,7 +24,7 @@ func fieldsOf(t reflect.Type) (fields []string) {
 func TestPrefsEqual(t *testing.T) {
 	tstest.PanicOnLog()
 
-	prefsHandles := []string{"ControlURL", "RouteAll", "AllowSingleHosts", "CorpDNS", "WantRunning", "ShieldsUp", "AdvertiseTags", "Hostname", "NotepadURLs", "DisableDERP", "AdvertiseRoutes", "NoSNAT", "NetfilterMode", "Persist"}
+	prefsHandles := []string{"ControlURL", "RouteAll", "AllowSingleHosts", "CorpDNS", "WantRunning", "ShieldsUp", "AdvertiseTags", "Hostname", "OSVersion", "DeviceModel", "NotepadURLs", "DisableDERP", "AdvertiseRoutes", "NoSNAT", "NetfilterMode", "Persist"}
 	if have := fieldsOf(reflect.TypeOf(Prefs{})); !reflect.DeepEqual(have, prefsHandles) {
 		t.Errorf("Prefs.Equal check might be out of sync\nfields: %q\nhandled: %q\n",
 			have, prefsHandles)