sherlock/internal/authn/login_test.go

package authn

import (
	"context"
	"crypto/ecdsa"
	"crypto/elliptic"
	"crypto/rand"
	"crypto/sha256"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"
	"net/url"
	"strings"
	"sync"
	"testing"
	"time"

	"github.com/coreos/go-oidc/v3/oidc"
	"github.com/go-jose/go-jose/v4"
	"github.com/go-jose/go-jose/v4/jwt"

	"gitea.alexandru.macocian.me/Charlie/sherlock/internal/keyring"
	fakekeyring "gitea.alexandru.macocian.me/Charlie/sherlock/internal/keyring/fake"
)

// stubAuthentik signs ES256 ID tokens and returns them through a real
// httptest.Server, exercising the full Login path end-to-end without
// touching a live Authentik instance.
type stubAuthentik struct {
	srv          *httptest.Server
	signer       jose.Signer
	pubJWK       jose.JSONWebKey
	verifyCalled bool
	mu           sync.Mutex
	codeToPKCE   map[string]string
}

func newStubAuthentik(t *testing.T) *stubAuthentik {
	t.Helper()
	priv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
	if err != nil {
		t.Fatal(err)
	}
	signer, err := jose.NewSigner(jose.SigningKey{Algorithm: jose.ES256, Key: priv},
		(&jose.SignerOptions{}).WithType("JWT").WithHeader("kid", "test"))
	if err != nil {
		t.Fatal(err)
	}
	stub := &stubAuthentik{
		signer: signer,
		pubJWK: jose.JSONWebKey{
			Key:       priv.Public(),
			KeyID:     "test",
			Algorithm: "ES256",
			Use:       "sig",
		},
		codeToPKCE: map[string]string{},
	}
	mux := http.NewServeMux()
	stub.srv = httptest.NewServer(mux)

	mux.HandleFunc("/.well-known/openid-configuration", func(w http.ResponseWriter, r *http.Request) {
		_ = json.NewEncoder(w).Encode(map[string]any{
			"issuer":                                stub.srv.URL,
			"authorization_endpoint":                stub.srv.URL + "/authorize",
			"token_endpoint":                        stub.srv.URL + "/token",
			"jwks_uri":                              stub.srv.URL + "/jwks",
			"response_types_supported":              []string{"code"},
			"subject_types_supported":               []string{"public"},
			"id_token_signing_alg_values_supported": []string{"ES256"},
		})
	})
	mux.HandleFunc("/jwks", func(w http.ResponseWriter, r *http.Request) {
		_ = json.NewEncoder(w).Encode(jose.JSONWebKeySet{Keys: []jose.JSONWebKey{stub.pubJWK}})
	})
	mux.HandleFunc("/authorize", func(w http.ResponseWriter, r *http.Request) {
		q := r.URL.Query()
		stub.mu.Lock()
		stub.codeToPKCE["code-"+q.Get("state")] = q.Get("code_challenge")
		stub.mu.Unlock()
		// Redirect to the loopback redirect URI with the code+state.
		ru, _ := url.Parse(q.Get("redirect_uri"))
		rq := ru.Query()
		rq.Set("code", "code-"+q.Get("state"))
		rq.Set("state", q.Get("state"))
		ru.RawQuery = rq.Encode()
		http.Redirect(w, r, ru.String(), http.StatusFound)
	})
	mux.HandleFunc("/token", func(w http.ResponseWriter, r *http.Request) {
		_ = r.ParseForm()

		// Refresh grant: hand back a rotated access token (and a fresh
		// id_token) without re-running the PKCE dance. Used by the
		// TokenSource renewal tests.
		if r.Form.Get("grant_type") == "refresh_token" {
			clientID := r.Form.Get("client_id")
			if clientID == "" {
				if user, _, ok := r.BasicAuth(); ok {
					clientID = user
				}
			}
			if clientID == "" {
				clientID = "test-client"
			}
			idToken := stub.signIDToken(t, clientID, map[string]any{
				"sub":   "user-1",
				"email": "ops@example.com",
				"name":  "Test Operator",
			})
			w.Header().Set("Content-Type", "application/json")
			_ = json.NewEncoder(w).Encode(map[string]any{
				"access_token":       "at-refreshed",
				"refresh_token":      "rt-2",
				"id_token":           idToken,
				"token_type":         "Bearer",
				"expires_in":         3600,
				"refresh_expires_in": 86400,
			})
			return
		}

		code := r.Form.Get("code")
		verifier := r.Form.Get("code_verifier")
		stub.mu.Lock()
		challenge, ok := stub.codeToPKCE[code]
		stub.mu.Unlock()
		if !ok {
			http.Error(w, "unknown code", http.StatusBadRequest)
			return
		}
		sum := sha256.Sum256([]byte(verifier))
		want := base64.RawURLEncoding.EncodeToString(sum[:])
		if want != challenge {
			http.Error(w, "bad code_verifier", http.StatusBadRequest)
			return
		}
		stub.verifyCalled = true
		// Public PKCE clients don't always send client_id in the body
		// (oauth2 prefers Basic-Auth when AuthStyle defaults to header).
		// Pull it from Authorization or fall back to the form/test value.
		clientID := r.Form.Get("client_id")
		if clientID == "" {
			if user, _, ok := r.BasicAuth(); ok {
				clientID = user
			}
		}
		if clientID == "" {
			clientID = "test-client"
		}
		idToken := stub.signIDToken(t, clientID, map[string]any{
			"sub":   "user-1",
			"email": "ops@example.com",
			"name":  "Test Operator",
		})
		resp := map[string]any{
			"access_token":       "at-1",
			"refresh_token":      "rt-1",
			"id_token":           idToken,
			"token_type":         "Bearer",
			"expires_in":         3600,
			"refresh_expires_in": 86400,
		}
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(resp)
	})
	t.Cleanup(stub.srv.Close)
	return stub
}

func (s *stubAuthentik) signIDToken(t *testing.T, audience string, claims map[string]any) string {
	t.Helper()
	now := time.Now()
	all := map[string]any{
		"iss": s.srv.URL,
		"aud": audience,
		"iat": now.Unix(),
		"exp": now.Add(time.Hour).Unix(),
	}
	for k, v := range claims {
		all[k] = v
	}
	tok, err := jwt.Signed(s.signer).Claims(all).Serialize()
	if err != nil {
		t.Fatal(err)
	}
	return tok
}

func TestLogin_HappyPath(t *testing.T) {
	stub := newStubAuthentik(t)
	cfg := Config{
		Issuer:               stub.srv.URL,
		ClientID:             "test-client",
		Scopes:               []string{"openid", "profile", "email"},
		LoopbackAddrOverride: "127.0.0.1:0",
	}

	// The browser-open hook drives the flow programmatically.
	var browserErr error
	opts := LoginOptions{
		OnAuthURL: func(u string) {
			resp, err := (&http.Client{
				CheckRedirect: func(*http.Request, []*http.Request) error {
					return http.ErrUseLastResponse
				},
			}).Get(u)
			if err != nil {
				browserErr = err
				return
			}
			defer func() { _ = resp.Body.Close() }()
			loc := resp.Header.Get("Location")
			if loc == "" {
				browserErr = fmt.Errorf("expected redirect, got %d", resp.StatusCode)
				return
			}
			// Follow the redirect into the loopback listener.
			cb, err := http.Get(loc)
			if err != nil {
				browserErr = err
				return
			}
			_, _ = io.Copy(io.Discard, cb.Body)
			_ = cb.Body.Close()
		},
	}

	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	res, err := Login(ctx, cfg, opts)
	if err != nil {
		t.Fatalf("Login: %v", err)
	}
	if browserErr != nil {
		t.Fatalf("browser stub: %v", browserErr)
	}
	if res.Tokens.IDToken == "" || res.Tokens.RefreshToken == "" {
		t.Fatalf("missing tokens: %+v", res.Tokens)
	}
	if res.Tokens.Subject != "user-1" || res.Tokens.Email != "ops@example.com" {
		t.Fatalf("claims wrong: %+v", res.Tokens)
	}
	if res.Tokens.ClientID != "test-client" {
		t.Fatalf("ClientID not persisted: %q", res.Tokens.ClientID)
	}
	if !strings.HasPrefix(res.Tokens.Issuer, "http://127.0.0.1:") {
		t.Fatalf("Issuer = %q", res.Tokens.Issuer)
	}
}

func TestLogin_NotConfigured(t *testing.T) {
	_, err := Login(context.Background(), Config{}, LoginOptions{})
	if err != ErrNotConfigured {
		t.Fatalf("err = %v, want ErrNotConfigured", err)
	}
}

func TestLogin_ContextCancel(t *testing.T) {
	stub := newStubAuthentik(t)
	cfg := Config{
		Issuer:               stub.srv.URL,
		ClientID:             "test-client",
		Scopes:               []string{"openid"},
		LoopbackAddrOverride: "127.0.0.1:0",
	}
	ctx, cancel := context.WithCancel(context.Background())
	go func() {
		time.Sleep(100 * time.Millisecond)
		cancel()
	}()
	_, err := Login(ctx, cfg, LoginOptions{OnAuthURL: func(string) {}})
	if err == nil {
		t.Fatal("expected error on cancel")
	}
}

// Sanity check that the verifier built off the stub provider works
// outside Login too — guards against accidental client-ID drift.
func TestIDTokenVerifies_AgainstStub(t *testing.T) {
	stub := newStubAuthentik(t)
	provider, err := oidc.NewProvider(context.Background(), stub.srv.URL)
	if err != nil {
		t.Fatal(err)
	}
	raw := stub.signIDToken(t, "client-x", map[string]any{"sub": "u"})
	if _, err := provider.Verifier(&oidc.Config{ClientID: "client-x"}).Verify(context.Background(), raw); err != nil {
		t.Fatal(err)
	}
}

func TestEnsureFresh_FastPath(t *testing.T) {
	store := fakekeyring.New()
	_ = store.Set("test", keyring.TokenSet{
		IDToken:     "ok",
		IDExpiresAt: time.Now().Add(time.Hour),
		Issuer:      "x",
		ClientID:    "y",
	})
	ts, err := EnsureFresh(context.Background(), store, "test", EnsureFreshOptions{LockPath: t.TempDir() + "/lock"})
	if err != nil {
		t.Fatalf("EnsureFresh: %v", err)
	}
	if ts.IDToken != "ok" {
		t.Fatal("fast path should return current token")
	}
}

func TestEnsureFresh_NoTokens(t *testing.T) {
	store := fakekeyring.New()
	_, err := EnsureFresh(context.Background(), store, "test", EnsureFreshOptions{LockPath: t.TempDir() + "/lock"})
	if err != keyring.ErrNoTokens {
		t.Fatalf("err = %v, want ErrNoTokens", err)
	}
}

func TestEnsureFresh_NeedsRefreshButNoRefreshToken(t *testing.T) {
	store := fakekeyring.New()
	_ = store.Set("test", keyring.TokenSet{
		IDToken:     "stale",
		IDExpiresAt: time.Now().Add(-time.Minute),
		Issuer:      "x",
		ClientID:    "y",
	})
	_, err := EnsureFresh(context.Background(), store, "test", EnsureFreshOptions{LockPath: t.TempDir() + "/lock"})
	if err != ErrNoRefreshToken {
		t.Fatalf("err = %v, want ErrNoRefreshToken", err)
	}
}