This commit simplifies the transaction pool's gas price validation logic while
maintaining network security through the existing minimum gas price requirement.
Changes:
- Set default PriceLimit to 0 (was 1), allowing transactions with zero tip
- Remove PriceLimit >= 1 validation in config sanitization
- Simplify Pending() method by using EffectiveGasTipIntCmp consistently
- Unify validateTxBasics() logic to use GasTipCapIntCmp for all transactions
Key Points:
1. Economic Protection: All transactions still require gasPrice >= 12.5 Gwei
(enforced by GetMinGasPrice check in validateTx), providing sufficient
protection against DoS attacks even with zero tip.
2. Miner Incentives: Since XDPoSChain includes baseFee in miner rewards
(unlike standard EIP-1559), miners still earn the full gasPrice even when
tip is 0. This maintains miner revenue while allowing greater flexibility.
3. Special Transactions: BlockSigner and Randomize contract transactions
remain exempt from gas price checks, as they are critical for consensus.
4. Code Quality: Reduces complexity by 11 lines and unifies validation logic,
making the codebase more maintainable.
Security Analysis:
- No nil pointer risks: EffectiveGasTipIntCmp has built-in nil handling
- No DoS vulnerability: 12.5 Gwei minimum ensures economic cost per transaction
- EIP-1559 compatible: Existing minGasPrice check covers all validation needs
- Backward compatible: Only relaxes restrictions, doesn't break existing behavior
This change benefits system transactions and special use cases while maintaining
all existing security guarantees through the network's minimum gas price floor.
