mcp-chassis/auth/bearer_test.go

package auth

import (
	"bytes"
	"context"
	"log/slog"
	"net/http"
	"net/http/httptest"
	"testing"

	"github.com/lestrrat-go/jwx/v2/jwk"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// unavailableValidator returns a validator whose JWKS cache cannot be fetched,
// so Validate fails with ErrUnavailable — simulating a Dex/JWKS outage.
func unavailableValidator(t *testing.T) *JWTValidator {
	t.Helper()
	return &JWTValidator{
		issuer:   "https://dex.example",
		jwksURI:  "http://127.0.0.1:0/jwks", // unregistered in cache → Get fails
		cache:    jwk.NewCache(context.Background()),
		audience: "",
	}
}

// #6: a JWKS/Dex outage at validation time is ErrUnavailable, distinct from a
// present-but-invalid token.
func TestValidate_JWKSUnreachable_IsUnavailable(t *testing.T) {
	t.Parallel()
	_, err := unavailableValidator(t).Validate(context.Background(), "some.jwt.token")
	require.Error(t, err)
	require.ErrorIs(t, err, ErrUnavailable)
}

// #6: when JWT validation can't complete because Dex is down, answer 503
// temporarily_unavailable rather than a generic 401.
func TestBearerMiddleware_DexDown_503(t *testing.T) {
	t.Parallel()
	h := BearerMiddleware("static-tok", unavailableValidator(t), "gitea", "",
		http.HandlerFunc(func(http.ResponseWriter, *http.Request) {
			t.Fatal("next must NOT be called when Dex is down")
		}))
	rec := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	req.Header.Set("Authorization", "Bearer aaa.bbb.ccc") // not the static token → JWT path
	h.ServeHTTP(rec, req)

	require.Equal(t, http.StatusServiceUnavailable, rec.Code)
	require.Contains(t, rec.Header().Get("WWW-Authenticate"), `error="temporarily_unavailable"`)
}

// #9: every rejection is audit-logged with reason, remote, token type, and a
// non-reversible token fingerprint — never the raw token.
func TestBearerMiddleware_AuditLogsRejection(t *testing.T) {
	var buf bytes.Buffer
	prev := slog.Default()
	slog.SetDefault(slog.New(slog.NewJSONHandler(&buf, &slog.HandlerOptions{Level: slog.LevelInfo})))
	defer slog.SetDefault(prev)

	h := BearerMiddleware("expected-secret", nil, "gitea", "",
		http.HandlerFunc(func(http.ResponseWriter, *http.Request) {}))
	rec := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	req.Header.Set("Authorization", "Bearer wrong-secret-value")
	h.ServeHTTP(rec, req)

	require.Equal(t, http.StatusUnauthorized, rec.Code)
	logged := buf.String()
	assert.Contains(t, logged, "static_token_mismatch")
	assert.Contains(t, logged, "token_fp")
	assert.NotContains(t, logged, "wrong-secret-value", "raw token must never be logged")
}

func TestBearerMiddleware_StaticTokenWins(t *testing.T) {
	t.Parallel()

	called := false
	next := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		called = true
		w.WriteHeader(http.StatusNoContent)
	})

	h := BearerMiddleware("supersecret", nil, "brain", "", next)

	rec := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	req.Header.Set("Authorization", "Bearer supersecret")
	h.ServeHTTP(rec, req)

	require.True(t, called, "next must be called on valid static token")
	require.Equal(t, http.StatusNoContent, rec.Code)
}

func TestBearerMiddleware_NoHeader_401NoChallengeWhenMetadataEmpty(t *testing.T) {
	t.Parallel()

	h := BearerMiddleware("any", nil, "brain", "", http.HandlerFunc(func(http.ResponseWriter, *http.Request) {}))

	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/", nil))

	require.Equal(t, http.StatusUnauthorized, rec.Code)
	require.Empty(t, rec.Header().Get("WWW-Authenticate"))
}

func TestBearerMiddleware_NoHeader_EmitsChallengeWhenMetadataSet(t *testing.T) {
	t.Parallel()

	h := BearerMiddleware("any", nil, "brain",
		"https://brain-mcp.d-ma.be/.well-known/oauth-protected-resource",
		http.HandlerFunc(func(http.ResponseWriter, *http.Request) {}))

	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/", nil))

	require.Equal(t, http.StatusUnauthorized, rec.Code)
	require.Equal(t,
		`Bearer realm="brain", resource_metadata="https://brain-mcp.d-ma.be/.well-known/oauth-protected-resource"`,
		rec.Header().Get("WWW-Authenticate"),
	)
}

func TestBearerMiddleware_WrongStaticToken_401(t *testing.T) {
	t.Parallel()

	h := BearerMiddleware("expected", nil, "brain", "", http.HandlerFunc(func(http.ResponseWriter, *http.Request) {
		t.Fatal("next must NOT be called on wrong token")
	}))

	rec := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	req.Header.Set("Authorization", "Bearer wrong")
	h.ServeHTTP(rec, req)

	require.Equal(t, http.StatusUnauthorized, rec.Code)
}

func TestBearerMiddleware_EmptyBearer_401(t *testing.T) {
	t.Parallel()

	h := BearerMiddleware("expected", nil, "brain", "",
		http.HandlerFunc(func(http.ResponseWriter, *http.Request) {
			t.Fatal("next must NOT be called on empty bearer")
		}))

	rec := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	req.Header.Set("Authorization", "Bearer ")
	h.ServeHTTP(rec, req)

	require.Equal(t, http.StatusUnauthorized, rec.Code)
}

func TestBearerMiddleware_StaticOnly_NilValidator_OK(t *testing.T) {
	t.Parallel()

	// Verifies that JWT-disabled deployments (validator == nil) work end-to-end.
	called := false
	h := BearerMiddleware("tok", nil, "brain", "",
		http.HandlerFunc(func(http.ResponseWriter, *http.Request) { called = true }))

	rec := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	req.Header.Set("Authorization", "Bearer tok")
	h.ServeHTTP(rec, req)

	require.True(t, called)
}

func TestJWTValidator_NilReturnsError(t *testing.T) {
	t.Parallel()

	var v *JWTValidator
	subj, err := v.Validate(t.Context(), "anything")
	require.Empty(t, subj)
	require.Error(t, err)
}