Merge pull request #77 from balancer/mkflow27/issue75

ezETH Mode Rate Provider

rate-providers/ezETHRateProviderMode.md

@@ -0,0 +1,47 @@
+# Rate Provider: `Api3AggregatorAdaptor`
+
+## Details
+- Reviewed by: @mkflow27
+- Checked by: @\<GitHub handle of secondary reviewer\>
+- Deployed at:
+    - [mode:0x054Ca7F10D555A0A34E35E6d95af9569468E40c0](https://explorer.mode.network/address/0x054Ca7F10D555A0A34E35E6d95af9569468E40c0?tab=read_contract)
+- Audit report(s):
+    - [API3 security](https://dapi-docs.api3.org/reference/dapis/understand/security.html)
+
+## Context
+This RateProvider is updated via the API3 product. It reports the exchangeRate of ETH/ezETH on mainnet. It is read on mainnet and available as an Oracle on mode. 
+
+## Review Checklist: Bare Minimum Compatibility
+Each of the items below represents an absolute requirement for the Rate Provider. If any of these is unchecked, the Rate Provider is unfit to use.
+
+- [x] Implements the [`IRateProvider`](https://github.com/balancer/balancer-v2-monorepo/blob/bc3b3fee6e13e01d2efe610ed8118fdb74dfc1f2/pkg/interfaces/contracts/pool-utils/IRateProvider.sol) interface.
+- [x] `getRate` returns an 18-decimal fixed point number (i.e., 1 == 1e18) regardless of underlying token decimals.
+
+## Review Checklist: Common Findings
+Each of the items below represents a common red flag found in Rate Provider contracts.
+
+If none of these is checked, then this might be a pretty great Rate Provider! If any of these is checked, we must thoroughly elaborate on the conditions that lead to the potential issue. Decision points are not binary; a Rate Provider can be safe despite these boxes being checked. A check simply indicates that thorough vetting is required in a specific area, and this vetting should be used to inform a holistic analysis of the Rate Provider.
+
+### Administrative Privileges
+- [ ] The Rate Provider is upgradeable (e.g., via a proxy architecture or an `onlyOwner` function that updates the price source address).
+
+- [ ] Some other portion of the price pipeline is upgradeable (e.g., the token itself, an oracle, or some piece of a larger system that tracks the price).
+
+### Oracles
+- [x] Price data is provided by an off-chain source (e.g., a Chainlink oracle, a multisig, or a network of nodes).
+    - source: API3. 
+    - source address: The data is sourced from multiple so called "beacons" which are a set of nodes which provide the rate data to be aggregated by the `Api3ServerV1` [mode:0x709944a48cAf83535e43471680fDA4905FB3920a](https://modescan.io/address/0x709944a48cAf83535e43471680fDA4905FB3920a/contract/34443/code)
+    - any protections? The rate is calculated as the median of all the rate data "fetched" from beacons. For more information about more protections see [api3 docs](https://docs.api3.org/reference/dapis/understand/deviations.html) and consult the `updateBeaconSetWithBeacons` & `updateOevProxyDataFeedWithSignedData` functions.
+
+- [ ] Price data is expected to be volatile (e.g., because it represents an open market price instead of a (mostly) monotonically increasing price).
+
+### Common Manipulation Vectors
+- [ ] The Rate Provider is susceptible to donation attacks.
+
+## Additional Findings
+To save time, we do not bother pointing out low-severity/informational issues or gas optimizations (unless the gas usage is particularly egregious). Instead, we focus only on high- and medium-severity findings which materially impact the contract's functionality and could harm users.
+
+## Conclusion
+**Summary judgment: SAFE**
+
+This rate provider should work well with Balancer pools. API3 updates the rate on mode regularly and has various protections in place to ensure the correct values are bridged accurately. 

rate-providers/registry.json

@@ -1029,6 +1029,7 @@
       "upgradeableComponents": []
     }
   },
+  "fraxtal": {},
   "gnosis": {
     "0x89C80A4540A00b5270347E02e2E144c71da2EceD": {
       "asset": "0xaf204776c7245bF4147c2612BF6e5972Ee483701",
@@ -1094,6 +1095,17 @@
       ]
     }
   },
+  "mode": {
+    "0x054Ca7F10D555A0A34E35E6d95af9569468E40c0": {
+      "asset": "0x2416092f143378750bb29b79eD961ab195CcEea5",
+      "name": "Api3AggregatorAdaptor",
+      "summary": "safe",
+      "review": "./ezETHRateProviderMode.md",
+      "warnings": [],
+      "factory": "",
+      "upgradeableComponents": []
+    }
+  },
   "optimism": {
     "0xe561451322a5efC51E6f8ffa558C7482c892Bc1A": {
       "asset": "0xA348700745D249c3b49D2c2AcAC9A5AE8155F826",
@@ -1445,7 +1457,5 @@
       "factory": "0x4132f7AcC9dB7A6cF7BE2Dd3A9DC8b30C7E6E6c8",
       "upgradeableComponents": []
     }
-  },
-  "mode": {},
-  "fraxtal": {}
+  }
 }