Fix /pairings handler rejecting ListPairings with "tlv8: EOF"

pairings.go

@@ -31,7 +31,7 @@ func (srv *Server) pairings(res http.ResponseWriter, req *http.Request) {
 
 	d := struct {
 		Method     byte   `tlv8:"0"`
-		Identifier string `tlv8:"1"`
+		Identifier string `tlv8:"1,optional"`
 		PublicKey  []byte `tlv8:"3,optional"`
 		Permission byte   `tlv8:"11,optional"`
 		State      byte   `tlv8:"6"`

pairings_test.go

@@ -0,0 +1,59 @@
+package hap
+
+import (
+	"github.com/brutella/hap/accessory"
+
+	"bytes"
+	"encoding/hex"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+// TestPairingsHandlerRequests is a regression test for the recurring
+// "pairings.go: tlv8: EOF" reports (#21, #44).
+//
+// A ListPairings request carries only Method (tag 0) and State (tag 6) — it has
+// no Identifier (tag 1). The handler decoded into a struct that marked
+// Identifier as required, so tlv8.UnmarshalReader returned io.EOF and the
+// handler rejected the request with HTTP 400. iOS uses ListPairings to
+// reconcile a home's controllers (e.g. resident HomePods/Apple TVs), so the
+// persistent error left it retrying forever and unable to converge.
+//
+// The bodies below are captured verbatim from a real iOS controller.
+func TestPairingsHandlerRequests(t *testing.T) {
+	a := accessory.New(accessory.Info{Name: "Test"}, accessory.TypeOutlet)
+	srv, err := NewServer(NewMemStore(), a)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	const addr = "192.0.2.10:50000"
+	srv.mux.Lock()
+	srv.sess[addr] = &session{Pairing: Pairing{Name: "admin", Permission: PermissionAdmin}}
+	srv.mux.Unlock()
+
+	cases := []struct {
+		name string
+		body string // hex, captured off the wire
+	}{
+		{"ListPairings", "000105060101"},
+		{"AddPairing", "000103060101012437463141374344452d454645442d343943342d394431462d39373245364645384544413203208d8b2b72ff96811a7e4ab6ef5e3719bcacc5582b293d5d2ea3fc74dbf13a68620b0101"},
+	}
+
+	for _, tc := range cases {
+		raw, err := hex.DecodeString(tc.body)
+		if err != nil {
+			t.Fatal(err)
+		}
+		req := httptest.NewRequest(http.MethodPost, "/pairings", bytes.NewReader(raw))
+		req.RemoteAddr = addr
+		rec := httptest.NewRecorder()
+
+		srv.pairings(rec, req)
+
+		if rec.Code != http.StatusOK {
+			t.Errorf("%s: handler returned HTTP %d, want 200 (request rejected — tlv8 unmarshal EOF on a valid request)", tc.name, rec.Code)
+		}
+	}
+}