Truncate approve request out of value bounds

README.md

@@ -208,8 +208,9 @@ and the lower 64 bits represents the decimals part, each consecutive
 lesser bit halving the value of the previous bit.
 
 For example, The byte value `00000000 00000002 a0000000 00000000`,
-representing a zero-stripped binary value of $10.101$, translates to the
+representing a zero-stripped binary value of $10.101$. This translates
-(base 10) decimal value $2.625$.
+to the (base 10) decimal value $2.625$. The decimal part is calculated
+as, from left to right: $(1 * 0.5) + (0 * 0.25) + (1 * 0.125)$.
 
 #### Calculating the demurrage parameter
 

doc/texinfo/contract.texi

@@ -105,7 +105,7 @@ The initial @emph{Sink Address}. The address may be altered as long as the @code
 
 The @emph{input parameter} to the contract is a 128-bit positive fixed-point number, where the most significant 64 bits represent the integer part, and the lower 64 bits represents the decimals part, each consecutive lesser bit halving the value of the previous bit.
 
-For example, The byte value @code{00000000 00000002 a0000000 00000000}, representing a zero-stripped binary value of @math{10.101}, translates to the (base 10) decimal value @math{2.625}.
+For example, The byte value @code{00000000 00000002 a0000000 00000000}, representing a zero-stripped binary value of @math{10.101}. This translates to the (base 10) decimal value @math{2.625}. The decimal part is calculated as, from left to right: @math{(1 * 0.5) + (0 * 0.25) + (1 * 0.125)}.
 
 @subsubsection Calculating the demurrage parameter
 

python/CHANGELOG

@@ -1,3 +1,7 @@
+- 0.5.5
+	* Make allowance method public
+- 0.5.4
+	* Add Transfer() event emission to sweep() in contract
 - 0.5.3
 	* Add texinfo documentation
 	* Add man page for publish tool

python/setup.cfg

@@ -1,6 +1,6 @@
 [metadata]
 name = erc20-demurrage-token
-version = 0.5.3
+version = 0.5.6
 description = ERC20 token with redistributed continual demurrage
 author = Louis Holbrook
 author_email = dev@holbrook.no

python/tests/test_basic.py

@@ -308,6 +308,30 @@ class TestBasic(TestDemurrageDefault):
         self.assertEqual(r['status'], 1)
 
 
+    def test_approve_max(self):
+        nonce_oracle = RPCNonceOracle(self.accounts[0], self.rpc)
+        c = DemurrageToken(self.chain_spec, signer=self.signer, nonce_oracle=nonce_oracle)
+        (tx_hash, o) = c.approve(self.address, self.accounts[0], self.accounts[1], int.from_bytes(b'\xff' * 32, byteorder='big'))
+        self.rpc.do(o)
+        o = receipt(tx_hash)
+        r = self.rpc.do(o)
+        self.assertEqual(r['status'], 1)
+
+        (tx_hash, o) = c.approve(self.address, self.accounts[0], self.accounts[1], 0)
+        self.rpc.do(o)
+        o = receipt(tx_hash)
+        r = self.rpc.do(o)
+        self.assertEqual(r['status'], 1)
+
+        self.backend.time_travel(self.start_time + (60 * 60 * 24 * 365 * 10))
+        c = DemurrageToken(self.chain_spec, signer=self.signer, nonce_oracle=nonce_oracle)
+        (tx_hash, o) = c.approve(self.address, self.accounts[0], self.accounts[1], int.from_bytes(b'\xff' * 32, byteorder='big'))
+        self.rpc.do(o)
+        o = receipt(tx_hash)
+        r = self.rpc.do(o)
+        self.assertEqual(r['status'], 1)
+
+
     def test_transfer_from(self):
         nonce_oracle = RPCNonceOracle(self.accounts[0], self.rpc)
         c = DemurrageToken(self.chain_spec, signer=self.signer, nonce_oracle=nonce_oracle)

solidity/DemurrageTokenSingleNocap.sol

@@ -6,6 +6,8 @@ import "aux/ABDKMath64x64.sol";
 
 contract DemurrageTokenSingleNocap {
 
+	uint256 constant VALUE_LIMIT = 1 << 63;
+
 	struct redistributionItem {
 		uint32 period;
 		uint72 value;
@@ -73,7 +75,7 @@ contract DemurrageTokenSingleNocap {
 	mapping (address => bool) minter;
 
 	// Storage for ERC20 approve/transferFrom methods
-	mapping (address => mapping (address => uint256 ) ) allowance; // holder -> spender -> amount (amount is subject to demurrage)
+	mapping (address => mapping (address => uint256 ) ) public allowance; // holder -> spender -> amount (amount is subject to demurrage)
 
 	// Address to send unallocated redistribution tokens
 	address public sinkAddress; 
@@ -253,7 +255,7 @@ contract DemurrageTokenSingleNocap {
 
 	// Implements Writer
 	function isWriter(address _minter) public view returns(bool) {
-		return minter[_minter];
+		return minter[_minter] || _minter == owner;
 	}
 
 	/// Implements ERC20
@@ -315,6 +317,7 @@ contract DemurrageTokenSingleNocap {
 		v = account[msg.sender];
 		account[msg.sender] = 0;
 		account[_account] += v;
+		emit Transfer(msg.sender, _account, v);
 		return v;
 	}
 
@@ -596,7 +599,14 @@ contract DemurrageTokenSingleNocap {
 		
 		changePeriod();
 
-		baseValue = toBaseAmount(_value);
+		// dex code will attempt uint256max approve, but contract cannot handle that size
+		// truncate to biggest possible value
+		if (_value <= VALUE_LIMIT) {
+			baseValue = toBaseAmount(_value);
+		} else {
+			baseValue = VALUE_LIMIT;
+		}
+
 		allowance[msg.sender][_spender] = baseValue;
 		emit Approval(msg.sender, _spender, _value);
 		return true;