New code verification service

api/server/internal/server/confirmationimp/store.go

@@ -0,0 +1,181 @@
+package confirmationimp
+
+import (
+	"context"
+	"crypto/rand"
+	"crypto/sha256"
+	"crypto/subtle"
+	"errors"
+	"time"
+
+	"github.com/tech/sendico/pkg/db/confirmation"
+	"github.com/tech/sendico/pkg/merrors"
+	"github.com/tech/sendico/pkg/model"
+	"go.mongodb.org/mongo-driver/bson/primitive"
+)
+
+var (
+	errConfirmationNotFound         = errors.New("confirmation not found or expired")
+	errConfirmationUsed             = errors.New("confirmation already used")
+	errConfirmationMismatch         = errors.New("confirmation code mismatch")
+	errConfirmationAttemptsExceeded = errors.New("confirmation attempts exceeded")
+	errConfirmationCooldown         = errors.New("confirmation cooldown active")
+	errConfirmationResendLimit      = errors.New("confirmation resend limit reached")
+)
+
+type ConfirmationStore struct {
+	db confirmation.DB
+}
+
+func NewStore(db confirmation.DB) *ConfirmationStore {
+	return &ConfirmationStore{db: db}
+}
+
+func (s *ConfirmationStore) Create(
+	ctx context.Context,
+	accountRef primitive.ObjectID,
+	destination string,
+	target model.ConfirmationTarget,
+	cfg Config,
+	generator func() (string, error),
+) (string, *model.ConfirmationCode, error) {
+	if err := s.db.DeleteTuple(ctx, accountRef, destination, target); err != nil && !errors.Is(err, merrors.ErrNoData) {
+		return "", nil, err
+	}
+
+	code, _, rec, err := s.buildRecord(accountRef, destination, target, cfg, generator)
+	if err != nil {
+		return "", nil, err
+	}
+
+	if err := s.db.Create(ctx, rec); err != nil {
+		return "", nil, err
+	}
+
+	return code, rec, nil
+}
+
+func (s *ConfirmationStore) Resend(
+	ctx context.Context,
+	accountRef primitive.ObjectID,
+	destination string,
+	target model.ConfirmationTarget,
+	cfg Config,
+	generator func() (string, error),
+) (string, *model.ConfirmationCode, error) {
+	now := time.Now().UTC()
+	active, err := s.db.FindActive(ctx, accountRef, destination, target, now.Unix())
+	if errors.Is(err, merrors.ErrNoData) {
+		return s.Create(ctx, accountRef, destination, target, cfg, generator)
+	}
+	if err != nil {
+		return "", nil, err
+	}
+	if active.ResendCount >= active.ResendLimit {
+		return "", nil, errConfirmationResendLimit
+	}
+	if now.Before(active.CooldownUntil) {
+		return "", nil, errConfirmationCooldown
+	}
+
+	code, salt, updated, err := s.buildRecord(accountRef, destination, target, cfg, generator)
+	if err != nil {
+		return "", nil, err
+	}
+	// Preserve attempt counters but bump resend count.
+	updated.ID = active.ID
+	updated.CreatedAt = active.CreatedAt
+	updated.Attempts = active.Attempts
+	updated.ResendCount = active.ResendCount + 1
+	updated.Salt = salt
+
+	if err := s.db.Update(ctx, updated); err != nil {
+		return "", nil, err
+	}
+	return code, updated, nil
+}
+
+func (s *ConfirmationStore) Verify(
+	ctx context.Context,
+	accountRef primitive.ObjectID,
+	destination string,
+	target model.ConfirmationTarget,
+	code string,
+) error {
+	now := time.Now().UTC()
+	rec, err := s.db.FindActive(ctx, accountRef, destination, target, now.Unix())
+	if errors.Is(err, merrors.ErrNoData) {
+		return errConfirmationNotFound
+	}
+	if err != nil {
+		return err
+	}
+	if rec.Used {
+		return errConfirmationUsed
+	}
+
+	rec.Attempts++
+	if rec.Attempts > rec.MaxAttempts {
+		rec.Used = true
+		_ = s.db.Update(ctx, rec)
+		return errConfirmationAttemptsExceeded
+	}
+
+	if subtle.ConstantTimeCompare(rec.CodeHash, hashCode(rec.Salt, code)) != 1 {
+		_ = s.db.Update(ctx, rec)
+		return errConfirmationMismatch
+	}
+
+	rec.Used = true
+	return s.db.Update(ctx, rec)
+}
+
+func (s *ConfirmationStore) buildRecord(
+	accountRef primitive.ObjectID,
+	destination string,
+	target model.ConfirmationTarget,
+	cfg Config,
+	generator func() (string, error),
+) (string, []byte, *model.ConfirmationCode, error) {
+	code, err := generator()
+	if err != nil {
+		return "", nil, nil, err
+	}
+	salt, err := newSalt()
+	if err != nil {
+		return "", nil, nil, err
+	}
+
+	now := time.Now().UTC()
+	rec := model.NewConfirmationCode(accountRef)
+	rec.Destination = destination
+	rec.Target = target
+	rec.CodeHash = hashCode(salt, code)
+	rec.Salt = salt
+	rec.ExpiresAt = now.Add(cfg.TTL)
+	rec.MaxAttempts = cfg.MaxAttempts
+	rec.ResendLimit = cfg.ResendLimit
+	rec.CooldownUntil = now.Add(cfg.Cooldown)
+	rec.Used = false
+	rec.Attempts = 0
+	rec.ResendCount = 0
+	rec.CreatedAt = now
+	rec.UpdatedAt = now
+
+	return code, salt, rec, nil
+}
+
+func hashCode(salt []byte, code string) []byte {
+	h := sha256.New()
+	h.Write(salt)
+	h.Write([]byte(code))
+	return h.Sum(nil)
+}
+
+func newSalt() ([]byte, error) {
+	buf := make([]byte, 16)
+	if _, err := rand.Read(buf); err != nil {
+		return nil, err
+	}
+	return buf, nil
+}