From ef5183474074d3bb684d075ebaaa65f1d64a0965 Mon Sep 17 00:00:00 2001
From: Mark Spanbroek <mark@spanbroek.net>
Date: Tue, 28 Jan 2025 16:08:11 +0100
Subject: [PATCH] vault: cannot burn flowing tokens

---
 contracts/vault/VaultBase.sol |  6 ++++++
 test/Vault.tests.js           | 16 ++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/contracts/vault/VaultBase.sol b/contracts/vault/VaultBase.sol
index 48553ac..600b284 100644
--- a/contracts/vault/VaultBase.sol
+++ b/contracts/vault/VaultBase.sol
@@ -110,9 +110,14 @@ abstract contract VaultBase {
     Context context,
     Recipient recipient
   ) internal {
+    Flow memory flow = _flows[controller][context][recipient];
+    require(flow.rate == TokensPerSecond.wrap(0), CannotBurnFlowingTokens());
+
     Balance memory balance = _getBalance(controller, context, recipient);
     uint128 amount = balance.available + balance.designated;
+
     _delete(controller, context, recipient);
+
     _token.safeTransfer(address(0xdead), amount);
   }
 
@@ -230,4 +235,5 @@ abstract contract VaultBase {
   error InvalidExpiry();
   error LockRequired();
   error NegativeFlow();
+  error CannotBurnFlowingTokens();
 }
diff --git a/test/Vault.tests.js b/test/Vault.tests.js
index 5de8280..1501408 100644
--- a/test/Vault.tests.js
+++ b/test/Vault.tests.js
@@ -598,6 +598,22 @@ describe("Vault", function () {
           vault.transfer(context, sender, receiver, 1)
         ).to.be.revertedWith("InsufficientBalance")
       })
+
+      it("cannot burn tokens that are flowing", async function () {
+        await vault.flow(context, sender, receiver, 5)
+        await expect(
+          vault.burn(context, sender)
+        ).to.be.revertedWith("CannotBurnFlowingTokens")
+        await expect(
+          vault.burn(context, receiver)
+        ).to.be.revertedWith("CannotBurnFlowingTokens")
+      })
+
+      it("can burn tokens that are no longer flowing", async function () {
+        await vault.flow(context, sender, receiver, 5)
+        await vault.flow(context, receiver, sender, 5)
+        await expect(vault.burn(context, sender)).not.to.be.reverted
+      })
     })
   })
 })