Support configuring Etherscan API key via config file (#1227)

Partially fixes #1226

lib/Echidna/Config.hs

@@ -56,6 +56,7 @@ instance FromJSON EConfigWithUsage where
               <*> (UIConf <$> v ..:? "timeout" <*> formatParser)
               <*> v ..:? "rpcUrl"
               <*> v ..:? "rpcBlock"
+              <*> v ..:? "etherscanApiKey"
       where
       useKey k = modify' $ Set.insert k
       x ..:? k = useKey k >> lift (x .:? k)

lib/Echidna/Onchain.hs

@@ -50,6 +50,11 @@ rpcBlockEnv = do
   val <- lookupEnv "ECHIDNA_RPC_BLOCK"
   pure (val >>= readMaybe)
 
+etherscanApiKey :: IO (Maybe Text)
+etherscanApiKey = do
+  val <- lookupEnv "ETHERSCAN_API_KEY"
+  pure (Text.pack <$> val)
+
 -- TODO: temporary solution, handle errors gracefully
 safeFetchContractFrom :: EVM.Fetch.BlockNumber -> Text -> Addr -> IO (Maybe Contract)
 safeFetchContractFrom rpcBlock rpcUrl addr =
@@ -122,11 +127,11 @@ readFileIfExists path = do
 
 -- | "Reverse engineer" the SolcContract and SourceCache structures for the
 -- code fetched from the outside
-externalSolcContract :: Addr -> Contract -> IO (Maybe (SourceCache, SolcContract))
-externalSolcContract addr c = do
+externalSolcContract :: Env -> Addr -> Contract -> IO (Maybe (SourceCache, SolcContract))
+externalSolcContract env addr c = do
   let runtimeCode = forceBuf $ fromJust $ view bytecode c
   putStr $ "Fetching Solidity source for contract at address " <> show addr <> "... "
-  srcRet <- Etherscan.fetchContractSource addr
+  srcRet <- Etherscan.fetchContractSource env.cfg.etherscanApiKey addr
   putStrLn $ if isJust srcRet then "Success!" else "Error!"
   putStr $ "Fetching Solidity source map for contract at address " <> show addr <> "... "
   srcmapRet <- Etherscan.fetchContractSourceMap addr
@@ -189,7 +194,7 @@ saveCoverageReport env runId = do
         forM_ (Map.toList contractsCache) $ \(addr, mc) ->
           case mc of
             Just contract -> do
-              r <- externalSolcContract addr contract
+              r <- externalSolcContract env addr contract
               case r of
                 Just (externalSourceCache, solcContract) -> do
                   let dir' = dir </> show addr

lib/Echidna/Types/Config.hs

@@ -43,6 +43,7 @@ data EConfig = EConfig
 
   , rpcUrl :: Maybe Text
   , rpcBlock :: Maybe Word64
+  , etherscanApiKey :: Maybe Text
   }
 
 instance Read OutputFormat where

lib/Etherscan.hs

@@ -10,7 +10,6 @@ import Data.Sequence (Seq)
 import Data.Text (Text)
 import Data.Text qualified as T
 import Network.HTTP.Simple (httpSink, parseRequest, getResponseBody, httpJSON)
-import System.Environment (lookupEnv)
 import Text.HTML.DOM (sinkDoc)
 import Text.XML.Cursor (attributeIs, content, element, fromDocument, ($//), (&//))
 
@@ -23,14 +22,13 @@ data SourceCode = SourceCode
   }
   deriving Show
 
-fetchContractSource :: Addr -> IO (Maybe SourceCode)
-fetchContractSource addr = do
-  apiKey <- lookupEnv "ETHERSCAN_API_KEY"
+fetchContractSource :: Maybe Text -> Addr -> IO (Maybe SourceCode)
+fetchContractSource apiKey addr = do
   url <- parseRequest $ "https://api.etherscan.io/api?"
                         <> "module=contract"
                         <> "&action=getsourcecode"
                         <> "&address=" <> show addr
-                        <> maybe "" ("&apikey=" <>) apiKey
+                        <> T.unpack (maybe "" ("&apikey=" <>) apiKey)
   try url (5 :: Int)
   where
   try url n = do

src/Main.hs

@@ -236,12 +236,14 @@ overrideConfig :: EConfig -> Options -> IO EConfig
 overrideConfig config Options{..} = do
   envRpcUrl <- Onchain.rpcUrlEnv
   envRpcBlock <- Onchain.rpcBlockEnv
+  envEtherscanApiKey <- Onchain.etherscanApiKey
   pure $
     config { solConf = overrideSolConf config.solConf
            , campaignConf = overrideCampaignConf config.campaignConf
            , uiConf = overrideUiConf config.uiConf
            , rpcUrl = cliRpcUrl <|> envRpcUrl <|> config.rpcUrl
            , rpcBlock = cliRpcBlock <|> envRpcBlock <|> config.rpcBlock
+           , etherscanApiKey = envEtherscanApiKey <|> config.etherscanApiKey
            }
            & overrideFormat
   where

tests/solidity/basic/default.yaml

@@ -87,6 +87,8 @@ maxValue: 100000000000000000000 # 100 eth
 rpcUrl: null
 # block number to use when fetching over RPC
 rpcBlock: null
+# Etherscan API key
+etherscanApiKey: null
 # number of workers
 workers: 1
 # events server port