Use ABI V2 to shorten settle arg list

This allows us to add additional arguments for hash salts and signatures
that allow settling on behalf of other users.

I kept compatibility with the existing signature and introduced a new
settle function using structs. Is this a good idea? Also a better name
than `settleChannel2` would be nice.

Closes raiden-network#1129

raiden_contracts/data/source/raiden/TokenNetwork.sol

@@ -1,4 +1,5 @@
 pragma solidity 0.6.4;
+pragma experimental ABIEncoderV2;
 
 import "lib/ECVerify.sol";
 import "raiden/Token.sol";
@@ -124,6 +125,13 @@ contract TokenNetwork is Utils {
         uint256 locked_amount;
     }
 
+    struct ParticipantSettleInput {
+        address participant;
+        uint256 transferred_amount;
+        uint256 locked_amount;
+        bytes32 locksroot;
+    }
+
     event ChannelOpened(
         uint256 indexed channel_identifier,
         address indexed participant1,
@@ -692,6 +700,30 @@ contract TokenNetwork is Utils {
         bytes32 participant2_locksroot
     )
         public
+    {
+        settleChannel2(
+            channel_identifier,
+            ParticipantSettleInput({
+                participant: participant1,
+                transferred_amount: participant1_transferred_amount,
+                locked_amount: participant1_locked_amount,
+                locksroot: participant1_locksroot
+            }),
+            ParticipantSettleInput({
+                participant: participant2,
+                transferred_amount: participant2_transferred_amount,
+                locked_amount: participant2_locked_amount,
+                locksroot: participant2_locksroot
+            })
+        );
+    }
+
+    function settleChannel2(
+        uint256 channel_identifier,
+        ParticipantSettleInput memory participant1_settlement,
+        ParticipantSettleInput memory participant2_settlement
+    )
+        public
     {
         // There are several requirements that this function MUST enforce:
         // - it MUST never fail; therefore, any overflows or underflows must be
@@ -708,6 +740,8 @@ contract TokenNetwork is Utils {
         // therefore it cannot ensure correctness. Users MUST use the official
         // Raiden clients for signing balance proofs.
 
+        address participant1 = participant1_settlement.participant;
+        address participant2 = participant2_settlement.participant;
         require(channel_identifier == getChannelIdentifier(participant1, participant2));
 
         bytes32 pair_hash;
@@ -725,16 +759,16 @@ contract TokenNetwork is Utils {
 
         require(verifyBalanceHashData(
             participant1_state,
-            participant1_transferred_amount,
-            participant1_locked_amount,
-            participant1_locksroot
+            participant1_settlement.transferred_amount,
+            participant1_settlement.locked_amount,
+            participant1_settlement.locksroot
         ));
 
         require(verifyBalanceHashData(
             participant2_state,
-            participant2_transferred_amount,
-            participant2_locked_amount,
-            participant2_locksroot
+            participant2_settlement.transferred_amount,
+            participant2_settlement.locked_amount,
+            participant2_settlement.locksroot
         ));
 
         // We are calculating the final token amounts that need to be
@@ -752,17 +786,17 @@ contract TokenNetwork is Utils {
         // We are reusing variables due to the local variables number limit.
         // For better readability this can be refactored further.
         (
-            participant1_transferred_amount,
-            participant2_transferred_amount,
-            participant1_locked_amount,
-            participant2_locked_amount
+            participant1_settlement.transferred_amount,
+            participant2_settlement.transferred_amount,
+            participant1_settlement.locked_amount,
+            participant2_settlement.locked_amount
         ) = getSettleTransferAmounts(
             participant1_state,
-            participant1_transferred_amount,
-            participant1_locked_amount,
+            participant1_settlement.transferred_amount,
+            participant1_settlement.locked_amount,
             participant2_state,
-            participant2_transferred_amount,
-            participant2_locked_amount
+            participant2_settlement.transferred_amount,
+            participant2_settlement.locked_amount
         );
 
         // Remove the channel data from storage
@@ -779,32 +813,32 @@ contract TokenNetwork is Utils {
             channel_identifier,
             participant1,
             participant2,
-            participant1_locked_amount,
-            participant1_locksroot
+            participant1_settlement.locked_amount,
+            participant1_settlement.locksroot
         );
         storeUnlockData(
             channel_identifier,
             participant2,
             participant1,
-            participant2_locked_amount,
-            participant2_locksroot
+            participant2_settlement.locked_amount,
+            participant2_settlement.locksroot
         );
 
         emit ChannelSettled(
             channel_identifier,
-            participant1_transferred_amount,
-            participant1_locksroot,
-            participant2_transferred_amount,
-            participant2_locksroot
+            participant1_settlement.transferred_amount,
+            participant1_settlement.locksroot,
+            participant2_settlement.transferred_amount,
+            participant2_settlement.locksroot
         );
 
         // Do the actual token transfers
-        if (participant1_transferred_amount > 0) {
-            require(token.transfer(participant1, participant1_transferred_amount));
+        if (participant1_settlement.transferred_amount > 0) {
+            require(token.transfer(participant1, participant1_settlement.transferred_amount));
         }
 
-        if (participant2_transferred_amount > 0) {
-            require(token.transfer(participant2, participant2_transferred_amount));
+        if (participant2_settlement.transferred_amount > 0) {
+            require(token.transfer(participant2, participant2_settlement.transferred_amount));
         }
     }
 

raiden_contracts/data/source/test/TokenNetworkInternalsTest.sol

@@ -1,4 +1,5 @@
 pragma solidity 0.6.4;
+pragma experimental ABIEncoderV2;
 
 import "raiden/TokenNetwork.sol";
 

raiden_contracts/tests/test_channel_settle.py

@@ -89,6 +89,66 @@ def test_settle_no_bp_success(
     assert custom_token.functions.balanceOf(B).call() == deposit_B
 
 
+def test_settle2_no_bp_success(
+    web3: Web3,
+    custom_token: Contract,
+    token_network: Contract,
+    create_channel_and_deposit: Callable,
+    get_accounts: Callable,
+    create_close_signature_for_no_balance_proof: Callable,
+) -> None:
+    """ The simplest settlement, tested against the V2 ABI settle """
+    (A, B) = get_accounts(2)
+    deposit_A = 10
+    deposit_B = 6
+    settle_timeout = TEST_SETTLE_TIMEOUT_MIN
+    channel_identifier = create_channel_and_deposit(A, B, deposit_A, deposit_B)
+    closing_sig = create_close_signature_for_no_balance_proof(A, channel_identifier)
+
+    # Close channel with no balance proof
+    call_and_transact(
+        token_network.functions.closeChannel(
+            channel_identifier,
+            B,
+            A,
+            EMPTY_BALANCE_HASH,
+            0,
+            EMPTY_ADDITIONAL_HASH,
+            EMPTY_SIGNATURE,
+            closing_sig,
+        ),
+        {"from": A},
+    )
+
+    # Do not call updateNonClosingBalanceProof
+
+    # Settlement window must be over before settling the channel
+    mine_blocks(web3, settle_timeout + 1)
+
+    # Settling the channel should work with no balance proofs
+    call_and_transact(
+        token_network.functions.settleChannel2(
+            channel_identifier=channel_identifier,
+            participant1_settlement=dict(
+                participant=A,
+                transferred_amount=0,
+                locked_amount=0,
+                locksroot=LOCKSROOT_OF_NO_LOCKS,
+            ),
+            participant2_settlement=dict(
+                participant=B,
+                transferred_amount=0,
+                locked_amount=0,
+                locksroot=LOCKSROOT_OF_NO_LOCKS,
+            ),
+        ),
+        {"from": A},
+    )
+
+    assert custom_token.functions.balanceOf(A).call() == deposit_A
+    assert custom_token.functions.balanceOf(B).call() == deposit_B
+
+
 def test_settle_channel_state(
     web3: Web3,
     get_accounts: Callable,