From b0736fe6f7b3f0ecb7f6c6606dea2a180b065b71 Mon Sep 17 00:00:00 2001
From: Maisem Ali <maisem@tailscale.com>
Date: Thu, 17 Nov 2022 00:07:21 +0500
Subject: [PATCH] ipn/ipnlocal: move selfNode from peerAPIServer to
 peerAPIHandler

The peerAPIHandler is instantiated per PeerAPI call so it is
guaranteed to have the latest selfNode.

Signed-off-by: Maisem Ali <maisem@tailscale.com>
---
 ipn/ipnlocal/local.go        |  1 -
 ipn/ipnlocal/peerapi.go      | 22 +++++++++++-----------
 ipn/ipnlocal/peerapi_test.go | 18 +++++++++---------
 3 files changed, 20 insertions(+), 21 deletions(-)

diff --git a/ipn/ipnlocal/local.go b/ipn/ipnlocal/local.go
index 147c9810e..f3a8518bd 100644
--- a/ipn/ipnlocal/local.go
+++ b/ipn/ipnlocal/local.go
@@ -2784,7 +2784,6 @@ func (b *LocalBackend) initPeerAPIListener() {
 	ps := &peerAPIServer{
 		b:                       b,
 		rootDir:                 fileRoot,
-		selfNode:                selfNode,
 		directFileMode:          b.directFileRoot != "",
 		directFileDoFinalRename: b.directFileDoFinalRename,
 	}
diff --git a/ipn/ipnlocal/peerapi.go b/ipn/ipnlocal/peerapi.go
index 902e3cc3b..382b4cadc 100644
--- a/ipn/ipnlocal/peerapi.go
+++ b/ipn/ipnlocal/peerapi.go
@@ -60,7 +60,6 @@ var addH2C func(*http.Server)
 type peerAPIServer struct {
 	b          *LocalBackend
 	rootDir    string // empty means file receiving unavailable
-	selfNode   *tailcfg.Node
 	knownEmpty atomic.Bool
 	resolver   *resolver.Resolver
 
@@ -514,10 +513,17 @@ func (pln *peerAPIListener) ServeConn(src netip.AddrPort, c net.Conn) {
 		c.Close()
 		return
 	}
+	nm := pln.lb.NetMap()
+	if nm == nil || nm.SelfNode == nil {
+		logf("peerapi: no netmap")
+		c.Close()
+		return
+	}
 	h := &peerAPIHandler{
 		ps:         pln.ps,
-		isSelf:     pln.ps.selfNode.User == peerNode.User,
+		isSelf:     nm.SelfNode.User == peerNode.User,
 		remoteAddr: src,
+		selfNode:   nm.SelfNode,
 		peerNode:   peerNode,
 		peerUser:   peerUser,
 	}
@@ -535,6 +541,7 @@ type peerAPIHandler struct {
 	ps         *peerAPIServer
 	remoteAddr netip.AddrPort
 	isSelf     bool                // whether peerNode is owned by same user as this node
+	selfNode   *tailcfg.Node       // this node; always non-nil
 	peerNode   *tailcfg.Node       // peerNode is who's making the request
 	peerUser   tailcfg.UserProfile // profile of peerNode
 }
@@ -552,7 +559,7 @@ func (h *peerAPIHandler) validateHost(r *http.Request) error {
 		return err
 	}
 	hostIPPfx := netip.PrefixFrom(ap.Addr(), ap.Addr().BitLen())
-	if !slices.Contains(h.ps.selfNode.Addresses, hostIPPfx) {
+	if !slices.Contains(h.selfNode.Addresses, hostIPPfx) {
 		return fmt.Errorf("%v not found in self addresses", hostIPPfx)
 	}
 	return nil
@@ -778,14 +785,7 @@ func (h *peerAPIHandler) canPutFile() bool {
 // canDebug reports whether h can debug this node (goroutines, metrics,
 // magicsock internal state, etc).
 func (h *peerAPIHandler) canDebug() bool {
-	// Reread the selfNode as it may have changed since the peerAPIServer
-	// was created.
-	// TODO(maisem): handle this in other places too.
-	nm := h.ps.b.NetMap()
-	if nm == nil || nm.SelfNode == nil {
-		return false
-	}
-	if !slices.Contains(nm.SelfNode.Capabilities, tailcfg.CapabilityDebug) {
+	if !slices.Contains(h.selfNode.Capabilities, tailcfg.CapabilityDebug) {
 		// This node does not expose debug info.
 		return false
 	}
diff --git a/ipn/ipnlocal/peerapi_test.go b/ipn/ipnlocal/peerapi_test.go
index 83fd01163..2da8d7a95 100644
--- a/ipn/ipnlocal/peerapi_test.go
+++ b/ipn/ipnlocal/peerapi_test.go
@@ -449,6 +449,9 @@ func TestHandlePeerAPI(t *testing.T) {
 					netip.MustParsePrefix("100.100.100.101/32"),
 				},
 			}
+			if tt.debugCap {
+				selfNode.Capabilities = append(selfNode.Capabilities, tailcfg.CapabilityDebug)
+			}
 			var e peerAPITestEnv
 			lb := &LocalBackend{
 				logf:           e.logBuf.Logf,
@@ -456,18 +459,15 @@ func TestHandlePeerAPI(t *testing.T) {
 				netMap:         &netmap.NetworkMap{SelfNode: selfNode},
 			}
 			e.ph = &peerAPIHandler{
-				isSelf: tt.isSelf,
+				isSelf:   tt.isSelf,
+				selfNode: selfNode,
 				peerNode: &tailcfg.Node{
 					ComputedName: "some-peer-name",
 				},
 				ps: &peerAPIServer{
-					b:        lb,
-					selfNode: selfNode,
+					b: lb,
 				},
 			}
-			if tt.debugCap {
-				e.ph.ps.selfNode.Capabilities = append(e.ph.ps.selfNode.Capabilities, tailcfg.CapabilityDebug)
-			}
 			var rootDir string
 			if !tt.omitRoot {
 				rootDir = t.TempDir()
@@ -507,9 +507,6 @@ func TestFileDeleteRace(t *testing.T) {
 			logf:           t.Logf,
 			capFileSharing: true,
 		},
-		selfNode: &tailcfg.Node{
-			Addresses: []netip.Prefix{netip.MustParsePrefix("100.100.100.101/32")},
-		},
 		rootDir: dir,
 	}
 	ph := &peerAPIHandler{
@@ -517,6 +514,9 @@ func TestFileDeleteRace(t *testing.T) {
 		peerNode: &tailcfg.Node{
 			ComputedName: "some-peer-name",
 		},
+		selfNode: &tailcfg.Node{
+			Addresses: []netip.Prefix{netip.MustParsePrefix("100.100.100.101/32")},
+		},
 		ps: ps,
 	}
 	buf := make([]byte, 2<<20)