feat: Missing Error Handling and Input Validation

[KevinMB0220]

Issue: Missing Error Handling and Input Validation

Description:

The codebase lacks comprehensive error handling and input validation throughout all systems. Many functions don't properly validate inputs, handle edge cases, or provide meaningful error messages, leading to potential security vulnerabilities and poor user experience.

Problems Identified:

1. Missing Input Validation: Functions don't validate input parameters for validity, ranges, or format
2. Incomplete Error Messages: Error messages are generic or missing, making debugging difficult
3. No Boundary Checks: Missing checks for array bounds, numeric limits, and overflow conditions
4. Insufficient Access Control: Some functions lack proper authorization checks
5. Missing State Validation: Functions don't validate system state before performing operations

Code Issues Found:

// In PlayerActions - Line 136: Basic validation but missing edge cases
assert(target.len() == target_types.len(), 'Target arrays length mismatch');
// Missing: Empty array validation, null checks, size limits

// In GearActions - Line 87: Basic validation but incomplete
assert(gear.owner == caller, 'Caller is not owner');
// Missing: Zero address checks, gear existence validation

// In CoreActions - Line 82: Basic admin check but missing validation
assert(caller == contract.admin, 'Only admin can spawn items');
// Missing: Contract state validation, admin role verification

Specific Problems:

1. Array Bounds Issues: No validation for array access, potential out-of-bounds errors
2. Numeric Overflow: No checks for u256 overflow in calculations
3. Address Validation: Missing zero address and invalid address checks
4. State Consistency: No validation that system state is consistent before operations
5. Resource Limits: No checks for resource exhaustion or limits

Impact:

• High Priority: Security vulnerabilities and system instability
• Potential for exploits through invalid inputs
• Poor user experience with unclear error messages
• System crashes from unhandled edge cases
• Difficult debugging and maintenance

Recommended Solutions:

1. Add Comprehensive Input Validation:

   fn validate_array_inputs(self: @ContractState, arrays: Array<Array<u256>>) -> bool {
       let mut i = 0;
       while i < arrays.len() {
           let arr = arrays.at(i);
           if arr.len() == 0 || arr.len() > 100 { // Reasonable limits
               return false;
           }
           i += 1;
       };
       true
   }
   
   fn validate_address(self: @ContractState, addr: ContractAddress) -> bool {
       !addr.is_zero()
   }
   
   fn validate_u256_range(self: @ContractState, value: u256, min: u256, max: u256) -> bool {
       value >= min && value <= max
   }

2. Implement Proper Error Handling:

   // Define comprehensive error constants
   pub mod Errors {
       pub const INVALID_ARRAY_LENGTH: felt252 = 'INVALID_ARRAY_LENGTH';
       pub const ARRAY_TOO_LARGE: felt252 = 'ARRAY_TOO_LARGE';
       pub const ZERO_ADDRESS: felt252 = 'ZERO_ADDRESS';
       pub const INVALID_RANGE: felt252 = 'INVALID_RANGE';
       pub const INSUFFICIENT_PERMISSIONS: felt252 = 'INSUFFICIENT_PERMISSIONS';
       pub const INVALID_STATE: felt252 = 'INVALID_STATE';
       pub const RESOURCE_LIMIT_EXCEEDED: felt252 = 'RESOURCE_LIMIT_EXCEEDED';
   }

3. Add State Validation Functions:

   fn validate_system_state(self: @ContractState) -> bool {
       let world = self.world_default();
       let contract: Contract = world.read_model(COA_CONTRACTS);
       
       // Validate contract state
       if contract.admin.is_zero() {
           return false;
       }
       
       // Validate ERC1155 contract
       if contract.erc1155.is_zero() {
           return false;
       }
       
       true
   }
   
   fn validate_player_state(self: @ContractState, player_id: ContractAddress) -> bool {
       let world = self.world_default();
       let player: Player = world.read_model(player_id);
       
       // Validate player exists and is properly initialized
       player.max_hp > 0 && !player.id.is_zero()
   }

4. Implement Safe Array Operations:

   fn safe_array_access(self: @ContractState, arr: @Array<u256>, index: u32) -> Option<u256> {
       if index >= arr.len() {
           return Option::None;
       }
       Option::Some(*arr.at(index))
   }
   
   fn validate_array_bounds(self: @ContractState, arr: @Array<u256>, index: u32) -> bool {
       index < arr.len()
   }

5. Add Resource Limit Checks:

   fn check_resource_limits(self: @ContractState, operation: felt252) -> bool {
       match operation {
           'SPAWN_ITEMS' => {
               // Check if spawning too many items at once
               // Implement rate limiting
           },
           'BATCH_OPERATIONS' => {
               // Check batch size limits
               // Prevent gas limit issues
           },
           'SESSION_CREATION' => {
               // Check session limits per player
               // Prevent spam
           },
           _ => true
       }
   }

6. Implement Comprehensive Validation in Critical Functions:

   fn deal_damage_with_validation(
       ref self: ContractState,
       target: Array<u256>,
       target_types: Array<felt252>,
       with_items: Array<u256>,
       session_id: felt252,
   ) {
       // Validate session
       self.validate_session_for_action(session_id);
       
       // Validate inputs
       assert(self.validate_array_inputs(array![target, with_items]), Errors::INVALID_ARRAY_LENGTH);
       assert(target.len() == target_types.len(), Errors::INVALID_ARRAY_LENGTH);
       assert(target.len() > 0 && target.len() <= 10, Errors::ARRAY_TOO_LARGE);
       
       // Validate system state
       assert(self.validate_system_state(), Errors::INVALID_STATE);
       
       // Validate caller
       let caller = get_caller_address();
       assert(self.validate_address(caller), Errors::ZERO_ADDRESS);
       assert(self.validate_player_state(caller), Errors::INVALID_STATE);
       
       // Proceed with damage logic
       self.deal_damage_internal(target, target_types, with_items, session_id);
   }

7. Add Access Control Validation:

   fn validate_admin_access(self: @ContractState) {
       let caller = get_caller_address();
       let world = self.world_default();
       let contract: Contract = world.read_model(COA_CONTRACTS);
       
       assert(self.validate_address(caller), Errors::ZERO_ADDRESS);
       assert(caller == contract.admin, Errors::INSUFFICIENT_PERMISSIONS);
   }
   
   fn validate_player_access(self: @ContractState, player_id: ContractAddress) {
       let caller = get_caller_address();
       assert(caller == player_id, Errors::INSUFFICIENT_PERMISSIONS);
       assert(self.validate_player_state(player_id), Errors::INVALID_STATE);
   }

Files Affected:

• src/systems/player.cairo - Add input validation to all functions
• src/systems/gear.cairo - Add validation to gear operations
• src/systems/core.cairo - Add validation to core functions
• src/systems/session.cairo - Add validation to session management
• src/helpers/ - Create validation helper functions

[ryzen-xp]

Hi,
I am a proficient blockchain developer with expertise in Cairo, Rust, and Solidity, as well as web development. I have contributed to multiple Starknet and Stellar projects and more.

• Additionally, I am a fellow of the OnlyDust fellowship program.*

Kindly assign me this issue.
Thank you!
ETA: 24 hours