all: fix full-tree golangci-lint findings

The new full-tree golangci-lint check reports issues the --new-from-rev
diff lint hid: nine wsl_v5 whitespace gaps, a prealloc, and an unparam
(setCSRFCookie never errored, so drop the return and update callers).
gocyclo on the central UpdateNodeFromMapRequest and an SA1019 NetMap
deprecation in an integration helper are suppressed with reasons.

Author: kradalby

cmd/headscale/cli/nodes.go

@@ -146,6 +146,7 @@ var listNodeRoutesCmd = &cobra.Command{
 		}
 
 		nodes := resp.JSON200.Nodes
+
 		if identifier != 0 {
 			idStr := strconv.FormatUint(identifier, util.Base10)
 			for _, node := range nodes {

hscontrol/derp/derp.go

@@ -28,6 +28,7 @@ func loadDERPMapFromPath(path string) (*tailcfg.DERPMap, error) {
 	}
 
 	var derpMap tailcfg.DERPMap
+
 	err = yaml.Unmarshal(b, &derpMap)
 
 	return &derpMap, err

hscontrol/derp/server/derp_server.go

@@ -80,6 +80,7 @@ func (d *DERPServer) GenerateRegion() (tailcfg.DERPRegion, error) {
 	host, portStr, err := net.SplitHostPort(serverURL.Host)
 
 	var port int
+
 	if err != nil {
 		host = serverURL.Host
 		if serverURL.Scheme == "https" {

hscontrol/mapper/node_conn.go

@@ -309,6 +309,7 @@ func (mc *multiChannelNodeConn) send(data *tailcfg.MapResponse) error {
 			snapshot = append(snapshot, conn)
 		}
 	}
+
 	mc.mutex.RUnlock()
 
 	if len(snapshot) == 0 {

hscontrol/oidc.go

@@ -156,18 +156,10 @@ func (a *AuthProviderOIDC) authHandler(
 	}
 
 	// Set the state and nonce cookies to protect against CSRF attacks
-	state, err := setCSRFCookie(writer, req, "state")
-	if err != nil {
-		httpUserError(writer, err)
-		return
-	}
+	state := setCSRFCookie(writer, req, "state")
 
 	// Set the state and nonce cookies to protect against CSRF attacks
-	nonce, err := setCSRFCookie(writer, req, "nonce")
-	if err != nil {
-		httpUserError(writer, err)
-		return
-	}
+	nonce := setCSRFCookie(writer, req, "nonce")
 
 	registrationInfo := AuthInfo{
 		AuthID:       authID,
@@ -928,7 +920,7 @@ func getCookieName(baseName, value string) string {
 	return fmt.Sprintf("%s_%s", baseName, value[:n])
 }
 
-func setCSRFCookie(w http.ResponseWriter, r *http.Request, name string) (string, error) {
+func setCSRFCookie(w http.ResponseWriter, r *http.Request, name string) string {
 	val := rands.HexString(64)
 
 	//nolint:gosec // G124: Secure set conditionally via r.TLS; HttpOnly + SameSite set below
@@ -948,5 +940,5 @@ func setCSRFCookie(w http.ResponseWriter, r *http.Request, name string) (string,
 	}
 	http.SetCookie(w, c)
 
-	return val, nil
+	return val
 }

hscontrol/oidc_test.go

@@ -186,8 +186,7 @@ func TestSetCSRFCookieSameSite(t *testing.T) {
 	w := httptest.NewRecorder()
 	r := httptest.NewRequestWithContext(t.Context(), http.MethodGet, "/auth/abcdef0123456789", nil)
 
-	_, err := setCSRFCookie(w, r, "state")
-	require.NoError(t, err)
+	setCSRFCookie(w, r, "state")
 
 	cookies := w.Result().Cookies()
 	require.Len(t, cookies, 1)

hscontrol/servertest/client.go

@@ -204,6 +204,7 @@ func (c *TestClient) startPollLoop() {
 
 	go func() {
 		defer close(c.pollDone)
+
 		_ = c.direct.PollNetMap(c.pollCtx, c)
 	}()
 }

hscontrol/state/state.go

@@ -2432,6 +2432,7 @@ func (s *State) HandleNodeFromPreAuthKey(
 				node.User = nil
 				node.Expiry = nil
 			}
+
 			node.AuthKey = pak
 			node.AuthKeyID = &pak.ID
 			// Do NOT reset IsOnline here. Online status is managed exclusively by
@@ -2793,7 +2794,7 @@ func isAutoDerivedGivenName(given, hostname string) bool {
 // - node.PeerChangeFromMapRequest
 // - node.ApplyPeerChange
 // - logTracePeerChange in poll.go.
-func (s *State) UpdateNodeFromMapRequest(id types.NodeID, req tailcfg.MapRequest) (change.Change, error) {
+func (s *State) UpdateNodeFromMapRequest(id types.NodeID, req tailcfg.MapRequest) (change.Change, error) { //nolint:gocyclo // central map-request reconciliation; the sequential branch flow reads clearer as one function than split across helpers
 	log.Trace().
 		Caller().
 		Uint64(zf.NodeID, id.Uint64()).

hscontrol/types/common.go

@@ -237,6 +237,7 @@ func (rn *AuthRequest) FinishAuth(verdict AuthVerdict) {
 	}
 
 	rn.finished <- verdict
+
 	close(rn.finished)
 }
 

hscontrol/util/dns.go

@@ -164,7 +164,7 @@ func GenerateIPv6DNSRootDomain(ipPrefix netip.Prefix) []dnsname.FQDN {
 	// but the inputs are not so long as to cause problems,
 	// and from what I can see, the generateMagicDNSRootDomains
 	// function is called only once over the lifetime of a server process.
-	prefixConstantParts := []string{}
+	prefixConstantParts := make([]string, 0, maskBits/nibbleLen)
 	for i := range maskBits / nibbleLen {
 		prefixConstantParts = append(prefixConstantParts, string(nibbleStr[i]))
 	}