add auth support

2026-04-17 13:19:08 +10:00
parent 9a561f3b07
commit ae3e2be89a
22 changed files with 2479 additions and 40 deletions
@@ -0,0 +1,292 @@
+package auth
+
+import (
+	"crypto/hmac"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"strings"
+	"time"
+)
+
+const (
+	jwtAlgHS256 = "HS256"
+	jwtTyp      = "JWT"
+)
+
+var (
+	ErrInvalidJWTConfig    = errors.New("invalid jwt config")
+	ErrInvalidJWTToken     = errors.New("invalid jwt token")
+	ErrInvalidJWTClaims    = errors.New("invalid jwt claims")
+	ErrExpiredJWTToken     = errors.New("jwt token expired")
+	ErrNotYetValidJWTToken = errors.New("jwt token is not yet valid")
+)
+
+type JWTConfig struct {
+	SigningKeyBase64 string
+	Issuer           string
+	Audience         string
+	TokenLifespan    time.Duration
+	ClockSkew        time.Duration
+}
+
+type Claims struct {
+	Subject   string   `json:"sub"`
+	Roles     []string `json:"roles,omitempty"`
+	Groups    []string `json:"groups,omitempty"`
+	Issuer    string   `json:"iss"`
+	Audience  string   `json:"aud"`
+	IssuedAt  int64    `json:"iat"`
+	ExpiresAt int64    `json:"exp"`
+	NotBefore int64    `json:"nbf"`
+	ID        string   `json:"jti"`
+}
+
+type JWTService struct {
+	signingKey    []byte
+	issuer        string
+	audience      string
+	tokenLifespan time.Duration
+	clockSkew     time.Duration
+	now           func() time.Time
+}
+
+type jwtHeader struct {
+	Algorithm string `json:"alg"`
+	Type      string `json:"typ"`
+}
+
+func NewJWTService(cfg JWTConfig) (*JWTService, error) {
+	issuer := strings.TrimSpace(cfg.Issuer)
+	audience := strings.TrimSpace(cfg.Audience)
+	if issuer == "" {
+		return nil, fmt.Errorf("%w: issuer is required", ErrInvalidJWTConfig)
+	}
+	if audience == "" {
+		return nil, fmt.Errorf("%w: audience is required", ErrInvalidJWTConfig)
+	}
+	if cfg.TokenLifespan <= 0 {
+		return nil, fmt.Errorf("%w: token lifespan must be greater than zero", ErrInvalidJWTConfig)
+	}
+	if cfg.ClockSkew < 0 {
+		return nil, fmt.Errorf("%w: clock skew cannot be negative", ErrInvalidJWTConfig)
+	}
+
+	signingKey, err := decodeBase64Key(strings.TrimSpace(cfg.SigningKeyBase64))
+	if err != nil {
+		return nil, fmt.Errorf("%w: signing key must be valid base64", ErrInvalidJWTConfig)
+	}
+	if len(signingKey) == 0 {
+		return nil, fmt.Errorf("%w: signing key cannot be empty", ErrInvalidJWTConfig)
+	}
+
+	return &JWTService{
+		signingKey:    signingKey,
+		issuer:        issuer,
+		audience:      audience,
+		tokenLifespan: cfg.TokenLifespan,
+		clockSkew:     cfg.ClockSkew,
+		now:           time.Now,
+	}, nil
+}
+
+func (s *JWTService) IssueToken(subject string, roles []string, groups []string) (string, Claims, error) {
+	subject = strings.TrimSpace(subject)
+	if subject == "" {
+		return "", Claims{}, fmt.Errorf("%w: subject is required", ErrInvalidJWTClaims)
+	}
+
+	now := s.now().UTC()
+	claims := Claims{
+		Subject:   subject,
+		Roles:     compactTrimmedStrings(roles),
+		Groups:    compactTrimmedStrings(groups),
+		Issuer:    s.issuer,
+		Audience:  s.audience,
+		IssuedAt:  now.Unix(),
+		ExpiresAt: now.Add(s.tokenLifespan).Unix(),
+		NotBefore: now.Unix(),
+		ID:        newTokenID(),
+	}
+	if err := validateClaims(claims, now, s.issuer, s.audience, s.clockSkew); err != nil {
+		return "", Claims{}, err
+	}
+
+	token, err := encodeSignedJWT(claims, s.signingKey)
+	if err != nil {
+		return "", Claims{}, err
+	}
+	return token, claims, nil
+}
+
+func (s *JWTService) VerifyToken(token string) (Claims, error) {
+	header, claims, signingInput, signature, err := parseJWT(token)
+	if err != nil {
+		return Claims{}, err
+	}
+	if header.Algorithm != jwtAlgHS256 {
+		return Claims{}, fmt.Errorf("%w: unsupported algorithm", ErrInvalidJWTToken)
+	}
+	if header.Type != "" && header.Type != jwtTyp {
+		return Claims{}, fmt.Errorf("%w: invalid token type", ErrInvalidJWTToken)
+	}
+
+	expected := signPayload(signingInput, s.signingKey)
+	if !hmac.Equal(signature, expected) {
+		return Claims{}, fmt.Errorf("%w: signature mismatch", ErrInvalidJWTToken)
+	}
+
+	now := s.now().UTC()
+	if err := validateClaims(claims, now, s.issuer, s.audience, s.clockSkew); err != nil {
+		return Claims{}, err
+	}
+	return claims, nil
+}
+
+func validateClaims(claims Claims, now time.Time, expectedIssuer string, expectedAudience string, clockSkew time.Duration) error {
+	if strings.TrimSpace(claims.Subject) == "" {
+		return fmt.Errorf("%w: subject is required", ErrInvalidJWTClaims)
+	}
+	if strings.TrimSpace(claims.ID) == "" {
+		return fmt.Errorf("%w: jti is required", ErrInvalidJWTClaims)
+	}
+	if claims.Issuer != expectedIssuer {
+		return fmt.Errorf("%w: issuer mismatch", ErrInvalidJWTClaims)
+	}
+	if claims.Audience != expectedAudience {
+		return fmt.Errorf("%w: audience mismatch", ErrInvalidJWTClaims)
+	}
+	if claims.IssuedAt <= 0 {
+		return fmt.Errorf("%w: iat is required", ErrInvalidJWTClaims)
+	}
+	if claims.NotBefore <= 0 {
+		return fmt.Errorf("%w: nbf is required", ErrInvalidJWTClaims)
+	}
+	if claims.ExpiresAt <= 0 {
+		return fmt.Errorf("%w: exp is required", ErrInvalidJWTClaims)
+	}
+	if claims.ExpiresAt <= claims.IssuedAt {
+		return fmt.Errorf("%w: exp must be greater than iat", ErrInvalidJWTClaims)
+	}
+	if claims.NotBefore > claims.ExpiresAt {
+		return fmt.Errorf("%w: nbf cannot be greater than exp", ErrInvalidJWTClaims)
+	}
+
+	unixNow := now.Unix()
+	skewSeconds := int64(clockSkew / time.Second)
+	if claims.IssuedAt > unixNow+skewSeconds {
+		return fmt.Errorf("%w: iat is in the future", ErrInvalidJWTClaims)
+	}
+	if claims.NotBefore > unixNow+skewSeconds {
+		return ErrNotYetValidJWTToken
+	}
+	if unixNow > claims.ExpiresAt+skewSeconds {
+		return ErrExpiredJWTToken
+	}
+	return nil
+}
+
+func encodeSignedJWT(claims Claims, signingKey []byte) (string, error) {
+	headerJSON, err := json.Marshal(jwtHeader{Algorithm: jwtAlgHS256, Type: jwtTyp})
+	if err != nil {
+		return "", fmt.Errorf("marshal jwt header: %w", err)
+	}
+	claimsJSON, err := json.Marshal(claims)
+	if err != nil {
+		return "", fmt.Errorf("marshal jwt claims: %w", err)
+	}
+
+	headerPart := base64.RawURLEncoding.EncodeToString(headerJSON)
+	payloadPart := base64.RawURLEncoding.EncodeToString(claimsJSON)
+	signingInput := headerPart + "." + payloadPart
+	signature := signPayload(signingInput, signingKey)
+	signaturePart := base64.RawURLEncoding.EncodeToString(signature)
+
+	return signingInput + "." + signaturePart, nil
+}
+
+func parseJWT(token string) (jwtHeader, Claims, string, []byte, error) {
+	parts := strings.Split(token, ".")
+	if len(parts) != 3 {
+		return jwtHeader{}, Claims{}, "", nil, fmt.Errorf("%w: malformed token", ErrInvalidJWTToken)
+	}
+	if parts[0] == "" || parts[1] == "" || parts[2] == "" {
+		return jwtHeader{}, Claims{}, "", nil, fmt.Errorf("%w: malformed token", ErrInvalidJWTToken)
+	}
+
+	headerBytes, err := base64.RawURLEncoding.DecodeString(parts[0])
+	if err != nil {
+		return jwtHeader{}, Claims{}, "", nil, fmt.Errorf("%w: invalid header encoding", ErrInvalidJWTToken)
+	}
+	payloadBytes, err := base64.RawURLEncoding.DecodeString(parts[1])
+	if err != nil {
+		return jwtHeader{}, Claims{}, "", nil, fmt.Errorf("%w: invalid payload encoding", ErrInvalidJWTToken)
+	}
+	signature, err := base64.RawURLEncoding.DecodeString(parts[2])
+	if err != nil {
+		return jwtHeader{}, Claims{}, "", nil, fmt.Errorf("%w: invalid signature encoding", ErrInvalidJWTToken)
+	}
+
+	var header jwtHeader
+	if err := json.Unmarshal(headerBytes, &header); err != nil {
+		return jwtHeader{}, Claims{}, "", nil, fmt.Errorf("%w: invalid header json", ErrInvalidJWTToken)
+	}
+	var claims Claims
+	if err := json.Unmarshal(payloadBytes, &claims); err != nil {
+		return jwtHeader{}, Claims{}, "", nil, fmt.Errorf("%w: invalid claims json", ErrInvalidJWTToken)
+	}
+
+	return header, claims, parts[0] + "." + parts[1], signature, nil
+}
+
+func signPayload(payload string, signingKey []byte) []byte {
+	mac := hmac.New(sha256.New, signingKey)
+	mac.Write([]byte(payload))
+	return mac.Sum(nil)
+}
+
+func newTokenID() string {
+	raw := make([]byte, 16)
+	if _, err := rand.Read(raw); err != nil {
+		return fmt.Sprintf("fallback-%d", time.Now().UTC().UnixNano())
+	}
+	return hex.EncodeToString(raw)
+}
+
+func decodeBase64Key(value string) ([]byte, error) {
+	encodings := []*base64.Encoding{
+		base64.StdEncoding,
+		base64.RawStdEncoding,
+		base64.URLEncoding,
+		base64.RawURLEncoding,
+	}
+	for _, encoding := range encodings {
+		decoded, err := encoding.DecodeString(value)
+		if err == nil {
+			return decoded, nil
+		}
+	}
+	return nil, errors.New("invalid base64 encoding")
+}
+
+func compactTrimmedStrings(values []string) []string {
+	if len(values) == 0 {
+		return nil
+	}
+	out := make([]string, 0, len(values))
+	for _, value := range values {
+		trimmed := strings.TrimSpace(value)
+		if trimmed == "" {
+			continue
+		}
+		out = append(out, trimmed)
+	}
+	if len(out) == 0 {
+		return nil
+	}
+	return out
+}
@@ -0,0 +1,247 @@
+package auth
+
+import (
+	"encoding/base64"
+	"errors"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestNewJWTServiceRejectsBadConfig(t *testing.T) {
+	_, err := NewJWTService(JWTConfig{
+		SigningKeyBase64: "!!!",
+		Issuer:           "vctp",
+		Audience:         "vctp-api",
+		TokenLifespan:    time.Hour,
+		ClockSkew:        time.Minute,
+	})
+	if err == nil {
+		t.Fatal("expected invalid base64 signing key to fail")
+	}
+	if !errors.Is(err, ErrInvalidJWTConfig) {
+		t.Fatalf("expected ErrInvalidJWTConfig, got: %v", err)
+	}
+}
+
+func TestIssueAndVerifyTokenRoundTrip(t *testing.T) {
+	now := time.Unix(1_700_000_000, 0).UTC()
+	svc := mustJWTService(t)
+	svc.now = func() time.Time { return now }
+
+	token, issuedClaims, err := svc.IssueToken("alice", []string{"admin", " viewer "}, []string{"cn=vctp-admins,dc=example,dc=com"})
+	if err != nil {
+		t.Fatalf("IssueToken returned error: %v", err)
+	}
+	if token == "" {
+		t.Fatal("expected non-empty token")
+	}
+	if issuedClaims.Subject != "alice" {
+		t.Fatalf("expected subject alice, got %q", issuedClaims.Subject)
+	}
+	if issuedClaims.Issuer != "vctp" {
+		t.Fatalf("expected issuer vctp, got %q", issuedClaims.Issuer)
+	}
+	if issuedClaims.Audience != "vctp-api" {
+		t.Fatalf("expected audience vctp-api, got %q", issuedClaims.Audience)
+	}
+	if issuedClaims.IssuedAt != now.Unix() {
+		t.Fatalf("unexpected iat: %d", issuedClaims.IssuedAt)
+	}
+	if issuedClaims.NotBefore != now.Unix() {
+		t.Fatalf("unexpected nbf: %d", issuedClaims.NotBefore)
+	}
+	if issuedClaims.ExpiresAt != now.Add(2*time.Hour).Unix() {
+		t.Fatalf("unexpected exp: %d", issuedClaims.ExpiresAt)
+	}
+	if issuedClaims.ID == "" {
+		t.Fatal("expected jti to be populated")
+	}
+
+	verifiedClaims, err := svc.VerifyToken(token)
+	if err != nil {
+		t.Fatalf("VerifyToken returned error: %v", err)
+	}
+	if verifiedClaims.Subject != issuedClaims.Subject {
+		t.Fatalf("subject mismatch: got %q want %q", verifiedClaims.Subject, issuedClaims.Subject)
+	}
+	if verifiedClaims.ID != issuedClaims.ID {
+		t.Fatalf("jti mismatch: got %q want %q", verifiedClaims.ID, issuedClaims.ID)
+	}
+}
+
+func TestVerifyTokenRejectsInvalidSignature(t *testing.T) {
+	svc := mustJWTService(t)
+	svc.now = func() time.Time { return time.Unix(1_700_000_000, 0).UTC() }
+
+	token, _, err := svc.IssueToken("alice", []string{"admin"}, nil)
+	if err != nil {
+		t.Fatalf("IssueToken returned error: %v", err)
+	}
+
+	other := mustJWTServiceWithKey(t, base64.StdEncoding.EncodeToString([]byte("a different secret key")))
+	other.now = svc.now
+
+	_, err = other.VerifyToken(token)
+	if err == nil {
+		t.Fatal("expected signature mismatch to fail")
+	}
+	if !errors.Is(err, ErrInvalidJWTToken) {
+		t.Fatalf("expected ErrInvalidJWTToken, got: %v", err)
+	}
+}
+
+func TestVerifyTokenRejectsIssuerAndAudienceMismatch(t *testing.T) {
+	issuerSvc := mustJWTService(t)
+	issuerSvc.now = func() time.Time { return time.Unix(1_700_000_000, 0).UTC() }
+	token, _, err := issuerSvc.IssueToken("alice", nil, nil)
+	if err != nil {
+		t.Fatalf("IssueToken returned error: %v", err)
+	}
+
+	wrongIssuer, err := NewJWTService(JWTConfig{
+		SigningKeyBase64: base64.StdEncoding.EncodeToString([]byte("super-secret-signing-key")),
+		Issuer:           "other-issuer",
+		Audience:         "vctp-api",
+		TokenLifespan:    2 * time.Hour,
+		ClockSkew:        time.Minute,
+	})
+	if err != nil {
+		t.Fatalf("failed to create verifier with wrong issuer: %v", err)
+	}
+	wrongIssuer.now = issuerSvc.now
+
+	_, err = wrongIssuer.VerifyToken(token)
+	if err == nil {
+		t.Fatal("expected issuer mismatch to fail")
+	}
+	if !errors.Is(err, ErrInvalidJWTClaims) {
+		t.Fatalf("expected ErrInvalidJWTClaims, got: %v", err)
+	}
+	if !strings.Contains(strings.ToLower(err.Error()), "issuer") {
+		t.Fatalf("expected issuer mismatch error, got: %v", err)
+	}
+
+	wrongAudience, err := NewJWTService(JWTConfig{
+		SigningKeyBase64: base64.StdEncoding.EncodeToString([]byte("super-secret-signing-key")),
+		Issuer:           "vctp",
+		Audience:         "other-audience",
+		TokenLifespan:    2 * time.Hour,
+		ClockSkew:        time.Minute,
+	})
+	if err != nil {
+		t.Fatalf("failed to create verifier with wrong audience: %v", err)
+	}
+	wrongAudience.now = issuerSvc.now
+
+	_, err = wrongAudience.VerifyToken(token)
+	if err == nil {
+		t.Fatal("expected audience mismatch to fail")
+	}
+	if !errors.Is(err, ErrInvalidJWTClaims) {
+		t.Fatalf("expected ErrInvalidJWTClaims, got: %v", err)
+	}
+	if !strings.Contains(strings.ToLower(err.Error()), "audience") {
+		t.Fatalf("expected audience mismatch error, got: %v", err)
+	}
+}
+
+func TestVerifyTokenRejectsExpiredNotBeforeAndFutureIssuedAt(t *testing.T) {
+	base := time.Unix(1_700_000_000, 0).UTC()
+	svc := mustJWTService(t)
+	svc.now = func() time.Time { return base }
+
+	token, claims, err := svc.IssueToken("alice", nil, nil)
+	if err != nil {
+		t.Fatalf("IssueToken returned error: %v", err)
+	}
+
+	svc.now = func() time.Time { return base.Add(3 * time.Hour) }
+	_, err = svc.VerifyToken(token)
+	if !errors.Is(err, ErrExpiredJWTToken) {
+		t.Fatalf("expected ErrExpiredJWTToken, got: %v", err)
+	}
+
+	notBeforeClaims := claims
+	notBeforeClaims.NotBefore = base.Add(10 * time.Minute).Unix()
+	notBeforeClaims.IssuedAt = base.Unix()
+	notBeforeClaims.ExpiresAt = base.Add(2 * time.Hour).Unix()
+	notBeforeClaims.ID = "forced-jti-1"
+	notBeforeToken, err := encodeSignedJWT(notBeforeClaims, svc.signingKey)
+	if err != nil {
+		t.Fatalf("failed to create token with future nbf: %v", err)
+	}
+	svc.now = func() time.Time { return base }
+	_, err = svc.VerifyToken(notBeforeToken)
+	if !errors.Is(err, ErrNotYetValidJWTToken) {
+		t.Fatalf("expected ErrNotYetValidJWTToken, got: %v", err)
+	}
+
+	futureIatClaims := claims
+	futureIatClaims.IssuedAt = base.Add(20 * time.Minute).Unix()
+	futureIatClaims.NotBefore = base.Unix()
+	futureIatClaims.ExpiresAt = base.Add(3 * time.Hour).Unix()
+	futureIatClaims.ID = "forced-jti-2"
+	futureIatToken, err := encodeSignedJWT(futureIatClaims, svc.signingKey)
+	if err != nil {
+		t.Fatalf("failed to create token with future iat: %v", err)
+	}
+	_, err = svc.VerifyToken(futureIatToken)
+	if err == nil {
+		t.Fatal("expected future iat validation to fail")
+	}
+	if !errors.Is(err, ErrInvalidJWTClaims) {
+		t.Fatalf("expected ErrInvalidJWTClaims for future iat, got: %v", err)
+	}
+}
+
+func TestVerifyTokenRejectsMissingJTI(t *testing.T) {
+	base := time.Unix(1_700_000_000, 0).UTC()
+	svc := mustJWTService(t)
+	svc.now = func() time.Time { return base }
+
+	token, claims, err := svc.IssueToken("alice", nil, nil)
+	if err != nil {
+		t.Fatalf("IssueToken returned error: %v", err)
+	}
+	if token == "" {
+		t.Fatal("expected non-empty token")
+	}
+
+	claims.ID = ""
+	customToken, err := encodeSignedJWT(claims, svc.signingKey)
+	if err != nil {
+		t.Fatalf("failed to create token without jti: %v", err)
+	}
+
+	_, err = svc.VerifyToken(customToken)
+	if err == nil {
+		t.Fatal("expected missing jti token to fail")
+	}
+	if !errors.Is(err, ErrInvalidJWTClaims) {
+		t.Fatalf("expected ErrInvalidJWTClaims, got: %v", err)
+	}
+	if !strings.Contains(strings.ToLower(err.Error()), "jti") {
+		t.Fatalf("expected jti validation error, got: %v", err)
+	}
+}
+
+func mustJWTService(t *testing.T) *JWTService {
+	t.Helper()
+	return mustJWTServiceWithKey(t, base64.StdEncoding.EncodeToString([]byte("super-secret-signing-key")))
+}
+
+func mustJWTServiceWithKey(t *testing.T, keyBase64 string) *JWTService {
+	t.Helper()
+	svc, err := NewJWTService(JWTConfig{
+		SigningKeyBase64: keyBase64,
+		Issuer:           "vctp",
+		Audience:         "vctp-api",
+		TokenLifespan:    2 * time.Hour,
+		ClockSkew:        time.Minute,
+	})
+	if err != nil {
+		t.Fatalf("failed to create jwt service: %v", err)
+	}
+	return svc
+}
@@ -0,0 +1,354 @@
+package auth
+
+import (
+	"context"
+	"crypto/tls"
+	"crypto/x509"
+	"errors"
+	"fmt"
+	"net"
+	"net/url"
+	"os"
+	"sort"
+	"strings"
+	"time"
+
+	"github.com/go-ldap/ldap/v3"
+)
+
+var (
+	ErrInvalidLDAPConfig      = errors.New("invalid ldap config")
+	ErrLDAPInvalidCredentials = errors.New("invalid ldap credentials")
+	ErrLDAPOperationFailed    = errors.New("ldap operation failed")
+)
+
+type LDAPConfig struct {
+	BindAddress       string
+	BaseDN            string
+	TrustCertFile     string
+	DisableValidation bool
+	Insecure          bool
+	DialTimeout       time.Duration
+}
+
+type LDAPIdentity struct {
+	Username string
+	UserDN   string
+	Groups   []string
+}
+
+type LDAPAuthenticator struct {
+	bindAddress       string
+	baseDN            string
+	trustCertFile     string
+	disableValidation bool
+	insecure          bool
+	dialTimeout       time.Duration
+}
+
+func NewLDAPAuthenticator(cfg LDAPConfig) (*LDAPAuthenticator, error) {
+	bindAddress := strings.TrimSpace(cfg.BindAddress)
+	baseDN := strings.TrimSpace(cfg.BaseDN)
+	trustCertFile := strings.TrimSpace(cfg.TrustCertFile)
+
+	if bindAddress == "" {
+		return nil, fmt.Errorf("%w: bind address is required", ErrInvalidLDAPConfig)
+	}
+	if baseDN == "" {
+		return nil, fmt.Errorf("%w: base DN is required", ErrInvalidLDAPConfig)
+	}
+	if _, err := url.ParseRequestURI(bindAddress); err != nil {
+		return nil, fmt.Errorf("%w: bind address must be a valid URL: %v", ErrInvalidLDAPConfig, err)
+	}
+
+	dialTimeout := cfg.DialTimeout
+	if dialTimeout <= 0 {
+		dialTimeout = 10 * time.Second
+	}
+
+	return &LDAPAuthenticator{
+		bindAddress:       bindAddress,
+		baseDN:            baseDN,
+		trustCertFile:     trustCertFile,
+		disableValidation: cfg.DisableValidation,
+		insecure:          cfg.Insecure,
+		dialTimeout:       dialTimeout,
+	}, nil
+}
+
+func (a *LDAPAuthenticator) AuthenticateAndFetchGroups(ctx context.Context, username string, password string) (LDAPIdentity, error) {
+	username = strings.TrimSpace(username)
+	if username == "" || password == "" {
+		return LDAPIdentity{}, ErrLDAPInvalidCredentials
+	}
+	if err := ctxErr(ctx); err != nil {
+		return LDAPIdentity{}, err
+	}
+
+	conn, err := a.connect()
+	if err != nil {
+		return LDAPIdentity{}, err
+	}
+	defer conn.Close()
+
+	if err := conn.Bind(username, password); err != nil {
+		if ldap.IsErrorWithCode(err, ldap.LDAPResultInvalidCredentials) {
+			return LDAPIdentity{}, ErrLDAPInvalidCredentials
+		}
+		return LDAPIdentity{}, fmt.Errorf("%w: bind failed: %v", ErrLDAPOperationFailed, err)
+	}
+	if err := ctxErr(ctx); err != nil {
+		return LDAPIdentity{}, err
+	}
+
+	identity := LDAPIdentity{
+		Username: username,
+		UserDN:   username,
+	}
+
+	entry, err := a.lookupUserEntry(conn, username)
+	if err != nil {
+		return LDAPIdentity{}, err
+	}
+	if entry != nil {
+		if strings.TrimSpace(entry.DN) != "" {
+			identity.UserDN = entry.DN
+		}
+		if v := firstNonEmpty(
+			entry.GetAttributeValue("uid"),
+			entry.GetAttributeValue("sAMAccountName"),
+			entry.GetAttributeValue("userPrincipalName"),
+			entry.GetAttributeValue("cn"),
+		); v != "" {
+			identity.Username = v
+		}
+	}
+
+	groupSet := make(map[string]struct{})
+	if entry != nil {
+		for _, groupDN := range entry.GetAttributeValues("memberOf") {
+			groupDN = strings.TrimSpace(groupDN)
+			if groupDN == "" {
+				continue
+			}
+			groupSet[groupDN] = struct{}{}
+		}
+	}
+
+	groupEntries, err := conn.Search(ldap.NewSearchRequest(
+		a.baseDN,
+		ldap.ScopeWholeSubtree,
+		ldap.NeverDerefAliases,
+		0,
+		0,
+		false,
+		fmt.Sprintf("(|(member=%s)(uniqueMember=%s)(memberUid=%s))",
+			ldap.EscapeFilter(identity.UserDN),
+			ldap.EscapeFilter(identity.UserDN),
+			ldap.EscapeFilter(username),
+		),
+		[]string{"dn"},
+		nil,
+	))
+	if err == nil {
+		for _, e := range groupEntries.Entries {
+			if dn := strings.TrimSpace(e.DN); dn != "" {
+				groupSet[dn] = struct{}{}
+			}
+		}
+	}
+
+	identity.Groups = mapKeysSorted(groupSet)
+	return identity, nil
+}
+
+func ResolveRoles(groupDNs []string, groupRoleMappings map[string]string) []string {
+	if len(groupDNs) == 0 || len(groupRoleMappings) == 0 {
+		return nil
+	}
+
+	normalizedMappings := make(map[string]string, len(groupRoleMappings))
+	for groupDN, role := range groupRoleMappings {
+		groupDN = normalizeDN(groupDN)
+		role = strings.ToLower(strings.TrimSpace(role))
+		if groupDN == "" || role == "" {
+			continue
+		}
+		normalizedMappings[groupDN] = role
+	}
+
+	roleSet := make(map[string]struct{})
+	for _, groupDN := range groupDNs {
+		if role, ok := normalizedMappings[normalizeDN(groupDN)]; ok {
+			roleSet[role] = struct{}{}
+		}
+	}
+	return mapKeysSorted(roleSet)
+}
+
+func HasAnyGroup(groupDNs []string, requiredGroupDNs []string) bool {
+	requiredGroupDNs = compactTrimmedStrings(requiredGroupDNs)
+	if len(requiredGroupDNs) == 0 {
+		return true
+	}
+	if len(groupDNs) == 0 {
+		return false
+	}
+
+	required := make(map[string]struct{}, len(requiredGroupDNs))
+	for _, groupDN := range requiredGroupDNs {
+		required[normalizeDN(groupDN)] = struct{}{}
+	}
+	for _, groupDN := range groupDNs {
+		if _, ok := required[normalizeDN(groupDN)]; ok {
+			return true
+		}
+	}
+	return false
+}
+
+func (a *LDAPAuthenticator) connect() (*ldap.Conn, error) {
+	tlsConfig, err := a.buildTLSConfig()
+	if err != nil {
+		return nil, err
+	}
+
+	parsedURL, err := url.Parse(a.bindAddress)
+	if err != nil {
+		return nil, fmt.Errorf("%w: invalid bind address: %v", ErrInvalidLDAPConfig, err)
+	}
+
+	options := []ldap.DialOpt{
+		ldap.DialWithDialer(&net.Dialer{Timeout: a.dialTimeout}),
+		ldap.DialWithTLSConfig(tlsConfig),
+	}
+	conn, err := ldap.DialURL(a.bindAddress, options...)
+	if err != nil {
+		return nil, fmt.Errorf("%w: unable to connect: %v", ErrLDAPOperationFailed, err)
+	}
+	conn.SetTimeout(a.dialTimeout)
+
+	// For ldap://, opportunistically upgrade to TLS unless explicitly configured as insecure.
+	if parsedURL.Scheme == "ldap" && !a.insecure {
+		if err := conn.StartTLS(tlsConfig); err != nil {
+			conn.Close()
+			return nil, fmt.Errorf("%w: starttls failed: %v", ErrLDAPOperationFailed, err)
+		}
+	}
+
+	return conn, nil
+}
+
+func (a *LDAPAuthenticator) buildTLSConfig() (*tls.Config, error) {
+	tlsConfig := &tls.Config{
+		MinVersion:         tls.VersionTLS12,
+		InsecureSkipVerify: a.insecure || a.disableValidation, //nolint:gosec // controlled by explicit config flags
+	}
+
+	if a.trustCertFile == "" {
+		return tlsConfig, nil
+	}
+
+	caPEM, err := os.ReadFile(a.trustCertFile)
+	if err != nil {
+		return nil, fmt.Errorf("%w: failed to read ldap trust cert file: %v", ErrInvalidLDAPConfig, err)
+	}
+	roots := x509.NewCertPool()
+	if !roots.AppendCertsFromPEM(caPEM) {
+		return nil, fmt.Errorf("%w: ldap trust cert file contains no valid certificates", ErrInvalidLDAPConfig)
+	}
+	tlsConfig.RootCAs = roots
+	return tlsConfig, nil
+}
+
+func (a *LDAPAuthenticator) lookupUserEntry(conn *ldap.Conn, username string) (*ldap.Entry, error) {
+	if looksLikeDN(username) {
+		searchRes, err := conn.Search(ldap.NewSearchRequest(
+			username,
+			ldap.ScopeBaseObject,
+			ldap.NeverDerefAliases,
+			1,
+			0,
+			false,
+			"(objectClass=*)",
+			[]string{"uid", "sAMAccountName", "userPrincipalName", "cn", "memberOf"},
+			nil,
+		))
+		if err != nil {
+			return nil, fmt.Errorf("%w: unable to load user entry: %v", ErrLDAPOperationFailed, err)
+		}
+		if len(searchRes.Entries) == 0 {
+			return nil, nil
+		}
+		return searchRes.Entries[0], nil
+	}
+
+	searchRes, err := conn.Search(ldap.NewSearchRequest(
+		a.baseDN,
+		ldap.ScopeWholeSubtree,
+		ldap.NeverDerefAliases,
+		2,
+		0,
+		false,
+		fmt.Sprintf("(|(uid=%s)(cn=%s)(sAMAccountName=%s)(userPrincipalName=%s))",
+			ldap.EscapeFilter(username),
+			ldap.EscapeFilter(username),
+			ldap.EscapeFilter(username),
+			ldap.EscapeFilter(username),
+		),
+		[]string{"uid", "sAMAccountName", "userPrincipalName", "cn", "memberOf"},
+		nil,
+	))
+	if err != nil {
+		return nil, fmt.Errorf("%w: user lookup failed: %v", ErrLDAPOperationFailed, err)
+	}
+	if len(searchRes.Entries) == 0 {
+		return nil, nil
+	}
+	return searchRes.Entries[0], nil
+}
+
+func normalizeDN(value string) string {
+	return strings.ToLower(strings.TrimSpace(value))
+}
+
+func mapKeysSorted[K ~string, V any](m map[K]V) []K {
+	if len(m) == 0 {
+		return nil
+	}
+	out := make([]K, 0, len(m))
+	for key := range m {
+		out = append(out, key)
+	}
+	sort.Slice(out, func(i, j int) bool {
+		return out[i] < out[j]
+	})
+	return out
+}
+
+func firstNonEmpty(values ...string) string {
+	for _, value := range values {
+		value = strings.TrimSpace(value)
+		if value != "" {
+			return value
+		}
+	}
+	return ""
+}
+
+func looksLikeDN(value string) bool {
+	value = strings.TrimSpace(value)
+	return strings.Contains(value, "=") && strings.Contains(value, ",")
+}
+
+func ctxErr(ctx context.Context) error {
+	if ctx == nil {
+		return nil
+	}
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	default:
+		return nil
+	}
+}
@@ -0,0 +1,39 @@
+package auth
+
+import "testing"
+
+func TestResolveRoles(t *testing.T) {
+	roles := ResolveRoles(
+		[]string{
+			"cn=vctp-admins,ou=groups,dc=example,dc=com",
+			" CN=VCTP-VIEWERS,OU=GROUPS,DC=EXAMPLE,DC=COM ",
+		},
+		map[string]string{
+			"cn=vctp-admins,ou=groups,dc=example,dc=com":  "admin",
+			"cn=vctp-viewers,ou=groups,dc=example,dc=com": "viewer",
+		},
+	)
+
+	if len(roles) != 2 {
+		t.Fatalf("expected 2 roles, got %d (%#v)", len(roles), roles)
+	}
+	if roles[0] != "admin" || roles[1] != "viewer" {
+		t.Fatalf("unexpected resolved roles: %#v", roles)
+	}
+}
+
+func TestHasAnyGroup(t *testing.T) {
+	groups := []string{
+		"cn=vctp-admins,ou=groups,dc=example,dc=com",
+	}
+
+	if !HasAnyGroup(groups, []string{" cn=vctp-admins,ou=groups,dc=example,dc=com "}) {
+		t.Fatal("expected group intersection to match")
+	}
+	if HasAnyGroup(groups, []string{"cn=vctp-operators,ou=groups,dc=example,dc=com"}) {
+		t.Fatal("expected no intersection")
+	}
+	if !HasAnyGroup(groups, nil) {
+		t.Fatal("expected empty required groups to allow")
+	}
+}