perf: sync protocol and core hardening updates

internal/rpc/rate_limit.go

@@ -2,14 +2,24 @@ package rpc
 
 import (
 	"context"
+	"crypto/sha256"
+	"encoding/hex"
 	"strconv"
 	"time"
 
 	"go.uber.org/zap"
+
+	"telesrv/internal/domain"
 )
 
 const sendRateLimitKeyPrefix = "messages:send:"
 
+const (
+	authCodePhoneRateLimitKeyPrefix   = "auth:code:phone-sha256:"
+	authCodeAuthKeyRateLimitKeyPrefix = "auth:code:raw-auth-key:"
+	defaultAuthCodeRateWindow         = 10 * time.Minute
+)
+
 const (
 	channelDifferenceRateLimitKeyPrefix = "updates:channeldifference:"
 	peerDialogsRateLimitKeyPrefix       = "messages:peerdialogs:"
@@ -65,3 +75,55 @@ func (r *Router) checkSendRateLimit(ctx context.Context, userID int64, cost int)
 	r.metrics().MessageRateLimited(retryAfter)
 	return floodWaitErr(retryAfter)
 }
+
+// checkAuthCodeRateLimit protects the unauthenticated code-issuance path before
+// any account lookup or durable 777000 write. Existing and unknown phone numbers
+// therefore consume identical budgets and cannot be distinguished through the
+// limiter. Plaintext phone numbers are never used as limiter keys or log fields.
+func (r *Router) checkAuthCodeRateLimit(ctx context.Context, phone string) error {
+	if r.deps.Limiter == nil {
+		return nil
+	}
+	normalizedPhone := domain.NormalizePhone(phone)
+	if !domain.ValidPhone(normalizedPhone) {
+		return phoneNumberInvalidErr()
+	}
+	window := r.cfg.AuthCodeRateWindow
+	if window <= 0 {
+		window = defaultAuthCodeRateWindow
+	}
+	// Check the connection/auth-key budget first. If that dimension is already
+	// blocked, changing phone strings cannot create one phone-digest Redis key
+	// per attempt and bypass the intended cardinality bound.
+	if limit := r.cfg.AuthCodeAuthKeyRateLimit; limit > 0 {
+		if rawAuthKeyID, ok := RawAuthKeyIDFrom(ctx); ok && rawAuthKeyID != ([8]byte{}) {
+			if err := r.checkAuthCodeRateLimitKey(ctx, authCodeAuthKeyRateLimitKeyPrefix+hex.EncodeToString(rawAuthKeyID[:]), limit, window, "raw_auth_key"); err != nil {
+				return err
+			}
+		}
+	}
+	if limit := r.cfg.AuthCodePhoneRateLimit; limit > 0 {
+		digest := sha256.Sum256([]byte(normalizedPhone))
+		if err := r.checkAuthCodeRateLimitKey(ctx, authCodePhoneRateLimitKeyPrefix+hex.EncodeToString(digest[:]), limit, window, "phone_digest"); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (r *Router) checkAuthCodeRateLimitKey(ctx context.Context, key string, limit int, window time.Duration, dimension string) error {
+	allowed, retryAfter, err := r.deps.Limiter.AllowN(ctx, key, 1, limit, window)
+	if err != nil {
+		return internalErr()
+	}
+	if allowed {
+		return nil
+	}
+	if retryAfter <= 0 {
+		retryAfter = 1
+	}
+	r.log.Debug("auth code issuance rate limited",
+		zap.String("dimension", dimension),
+		zap.Int("retry_after", retryAfter))
+	return floodWaitErr(retryAfter)
+}