Merge branch 'master' into fix-tooltip

13 files changed, 216 insertions, 195 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4fb81c350..5928d5cb4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,8 +5,10 @@
 - Add ability to export private keys as a file.
 - Add ability to export seed words as a file.
 - Changed state logs to a file download than a clipboard copy.
+- Fixed a long standing memory leak associated with filters installed by dapps
 - Fix link to support center.
 - Fixed tooltip icon locations to avoid overflow.
+- Warn users when a dapp proposes a high gas limit (90% of blockGasLimit or higher)
 
 ## 3.10.0 2017-9-11
 
diff --git a/app/scripts/background.js b/app/scripts/background.js
index f077ca7a8..1b96d68b5 100644
--- a/app/scripts/background.js
+++ b/app/scripts/background.js
@@ -1,6 +1,8 @@
 const urlUtil = require('url')
 const endOfStream = require('end-of-stream')
 const pipe = require('pump')
+const log = require('loglevel')
+const extension = require('extensionizer')
 const LocalStorageStore = require('obs-store/lib/localStorage')
 const storeTransform = require('obs-store/lib/transform')
 const ExtensionPlatform = require('./platforms/extension')
@@ -9,13 +11,11 @@ const migrations = require('./migrations/')
 const PortStream = require('./lib/port-stream.js')
 const NotificationManager = require('./lib/notification-manager.js')
 const MetamaskController = require('./metamask-controller')
-const extension = require('extensionizer')
 const firstTimeState = require('./first-time-state')
 
 const STORAGE_KEY = 'metamask-config'
 const METAMASK_DEBUG = 'GULP_METAMASK_DEBUG'
 
-const log = require('loglevel')
 window.log = log
 log.setDefaultLevel(METAMASK_DEBUG ? 'debug' : 'warn')
 
@@ -29,12 +29,12 @@ let popupIsOpen = false
 const diskStore = new LocalStorageStore({ storageKey: STORAGE_KEY })
 
 // initialization flow
-initialize().catch(console.error)
+initialize().catch(log.error)
 
 async function initialize () {
   const initState = await loadStateFromPersistence()
   await setupController(initState)
-  console.log('MetaMask initialization complete.')
+  log.debug('MetaMask initialization complete.')
 }
 
 //
diff --git a/app/scripts/contentscript.js b/app/scripts/contentscript.js
index acacf5d4c..90a0f1f22 100644
--- a/app/scripts/contentscript.js
+++ b/app/scripts/contentscript.js
@@ -1,11 +1,12 @@
+const fs = require('fs')
+const path = require('path')
+const pump = require('pump')
 const LocalMessageDuplexStream = require('post-message-stream')
 const PongStream = require('ping-pong-stream/pong')
-const PortStream = require('./lib/port-stream.js')
-const ObjectMultiplex = require('./lib/obj-multiplex')
+const ObjectMultiplex = require('obj-multiplex')
 const extension = require('extensionizer')
+const PortStream = require('./lib/port-stream.js')
 
-const fs = require('fs')
-const path = require('path')
 const inpageText = fs.readFileSync(path.join(__dirname, 'inpage.js')).toString()
 
 // Eventually this streaming injection could be replaced with:
@@ -50,22 +51,42 @@ function setupStreams () {
   pageStream.pipe(pluginStream).pipe(pageStream)
 
   // setup local multistream channels
-  const mx = ObjectMultiplex()
-  mx.on('error', console.error)
-  mx.pipe(pageStream).pipe(mx)
-  mx.pipe(pluginStream).pipe(mx)
+  const mux = new ObjectMultiplex()
+  pump(
+    mux,
+    pageStream,
+    mux,
+    (err) => logStreamDisconnectWarning('MetaMask Inpage', err)
+  )
+  pump(
+    mux,
+    pluginStream,
+    mux,
+    (err) => logStreamDisconnectWarning('MetaMask Background', err)
+  )
 
   // connect ping stream
   const pongStream = new PongStream({ objectMode: true })
-  pongStream.pipe(mx.createStream('pingpong')).pipe(pongStream)
+  pump(
+    mux,
+    pongStream,
+    mux,
+    (err) => logStreamDisconnectWarning('MetaMask PingPongStream', err)
+  )
 
   // connect phishing warning stream
-  const phishingStream = mx.createStream('phishing')
+  const phishingStream = mux.createStream('phishing')
   phishingStream.once('data', redirectToPhishingWarning)
 
   // ignore unused channels (handled by background, inpage)
-  mx.ignoreStream('provider')
-  mx.ignoreStream('publicConfig')
+  mux.ignoreStream('provider')
+  mux.ignoreStream('publicConfig')
+}
+
+function logStreamDisconnectWarning (remoteLabel, err) {
+  let warningMsg = `MetamaskContentscript - lost connection to ${remoteLabel}`
+  if (err) warningMsg += '\n' + err.stack
+  console.warn(warningMsg)
 }
 
 function shouldInjectWeb3 () {
diff --git a/app/scripts/lib/createLoggerMiddleware.js b/app/scripts/lib/createLoggerMiddleware.js
new file mode 100644
index 000000000..b92a965de
--- /dev/null
+++ b/app/scripts/lib/createLoggerMiddleware.js
@@ -0,0 +1,15 @@
+// log rpc activity
+module.exports = createLoggerMiddleware
+
+function createLoggerMiddleware({ origin }) {
+  return function loggerMiddleware (req, res, next, end) {
+    next((cb) => {
+      if (res.error) {
+        log.error('Error in RPC response:\n', res)
+      }
+      if (req.isMetamaskInternal) return
+      log.info(`RPC (${origin}):`, req, '->', res)
+      cb()
+    })
+  }
+}
\ No newline at end of file
diff --git a/app/scripts/lib/createOriginMiddleware.js b/app/scripts/lib/createOriginMiddleware.js
new file mode 100644
index 000000000..e1e097cc4
--- /dev/null
+++ b/app/scripts/lib/createOriginMiddleware.js
@@ -0,0 +1,9 @@
+// append dapp origin domain to request
+module.exports = createOriginMiddleware
+
+function createOriginMiddleware({ origin }) {
+  return function originMiddleware (req, res, next, end) {
+    req.origin = origin
+    next()
+  }
+}
\ No newline at end of file
diff --git a/app/scripts/lib/createProviderMiddleware.js b/app/scripts/lib/createProviderMiddleware.js
new file mode 100644
index 000000000..6dd192411
--- /dev/null
+++ b/app/scripts/lib/createProviderMiddleware.js
@@ -0,0 +1,13 @@
+
+module.exports = createProviderMiddleware
+
+// forward requests to provider
+function createProviderMiddleware({ provider }) {
+  return (req, res, next, end) => {
+    provider.sendAsync(req, (err, _res) => {
+      if (err) return end(err)
+      res.result = _res.result
+      end()
+    })
+  }
+}
\ No newline at end of file
diff --git a/app/scripts/lib/inpage-provider.js b/app/scripts/lib/inpage-provider.js
index 13888dc67..da75c4be2 100644
--- a/app/scripts/lib/inpage-provider.js
+++ b/app/scripts/lib/inpage-provider.js
@@ -1,8 +1,9 @@
-const pipe = require('pump')
-const StreamProvider = require('web3-stream-provider')
+const pump = require('pump')
+const RpcEngine = require('json-rpc-engine')
+const createIdRemapMiddleware = require('json-rpc-engine/src/idRemapMiddleware')
+const createStreamMiddleware = require('json-rpc-middleware-stream')
 const LocalStorageStore = require('obs-store')
-const ObjectMultiplex = require('./obj-multiplex')
-const createRandomId = require('./random-id')
+const ObjectMultiplex = require('obj-multiplex')
 
 module.exports = MetamaskInpageProvider
 
@@ -10,64 +11,46 @@ function MetamaskInpageProvider (connectionStream) {
   const self = this
 
   // setup connectionStream multiplexing
-  var multiStream = self.multiStream = ObjectMultiplex()
-  pipe(
+  const mux = self.mux = new ObjectMultiplex()
+  pump(
     connectionStream,
-    multiStream,
+    mux,
     connectionStream,
     (err) => logStreamDisconnectWarning('MetaMask', err)
   )
 
   // subscribe to metamask public config (one-way)
   self.publicConfigStore = new LocalStorageStore({ storageKey: 'MetaMask-Config' })
-  pipe(
-    multiStream.createStream('publicConfig'),
+  pump(
+    mux.createStream('publicConfig'),
     self.publicConfigStore,
     (err) => logStreamDisconnectWarning('MetaMask PublicConfigStore', err)
   )
 
   // ignore phishing warning message (handled elsewhere)
-  multiStream.ignoreStream('phishing')
+  mux.ignoreStream('phishing')
 
   // connect to async provider
-  const asyncProvider = self.asyncProvider = new StreamProvider()
-  pipe(
-    asyncProvider,
-    multiStream.createStream('provider'),
-    asyncProvider,
+  const streamMiddleware = createStreamMiddleware()
+  pump(
+    streamMiddleware.stream,
+    mux.createStream('provider'),
+    streamMiddleware.stream,
     (err) => logStreamDisconnectWarning('MetaMask RpcProvider', err)
   )
-  // start and stop polling to unblock first block lock
 
-  self.idMap = {}
+  // handle sendAsync requests via dapp-side rpc engine
+  const rpcEngine = new RpcEngine()
+  rpcEngine.push(createIdRemapMiddleware())
+  rpcEngine.push(streamMiddleware)
+  self.rpcEngine = rpcEngine
 }
 
 // handle sendAsync requests via asyncProvider
 // also remap ids inbound and outbound
 MetamaskInpageProvider.prototype.sendAsync = function (payload, cb) {
   const self = this
-
-  // rewrite request ids
-  const request = eachJsonMessage(payload, (_message) => {
-    const message = Object.assign({}, _message)
-    const newId = createRandomId()
-    self.idMap[newId] = message.id
-    message.id = newId
-    return message
-  })
-
-  // forward to asyncProvider
-  self.asyncProvider.sendAsync(request, (err, _res) => {
-    if (err) return cb(err)
-    // transform messages to original ids
-    const res = eachJsonMessage(_res, (message) => {
-      const oldId = self.idMap[message.id]
-      delete self.idMap[message.id]
-      message.id = oldId
-      return message
-    })
-    cb(null, res)
-  })
+  self.rpcEngine.handle(payload, cb)
 }
 
 
@@ -124,14 +107,6 @@ MetamaskInpageProvider.prototype.isMetaMask = true
 
 // util
 
-function eachJsonMessage (payload, transformFn) {
-  if (Array.isArray(payload)) {
-    return payload.map(transformFn)
-  } else {
-    return transformFn(payload)
-  }
-}
-
 function logStreamDisconnectWarning (remoteLabel, err) {
   let warningMsg = `MetamaskInpageProvider - lost connection to ${remoteLabel}`
   if (err) warningMsg += '\n' + err.stack
diff --git a/app/scripts/lib/obj-multiplex.js b/app/scripts/lib/obj-multiplex.js
deleted file mode 100644
index 0034febe0..000000000
--- a/app/scripts/lib/obj-multiplex.js
+++ /dev/null
@@ -1,48 +0,0 @@
-const through = require('through2')
-
-module.exports = ObjectMultiplex
-
-function ObjectMultiplex (opts) {
-  opts = opts || {}
-  // create multiplexer
-  const mx = through.obj(function (chunk, enc, cb) {
-    const name = chunk.name
-    const data = chunk.data
-    if (!name) {
-      console.warn(`ObjectMultiplex - Malformed chunk without name "${chunk}"`)
-      return cb()
-    }
-    const substream = mx.streams[name]
-    if (!substream) {
-      console.warn(`ObjectMultiplex - orphaned data for stream "${name}"`)
-    } else {
-      if (substream.push) substream.push(data)
-    }
-    return cb()
-  })
-  mx.streams = {}
-  // create substreams
-  mx.createStream = function (name) {
-    const substream = mx.streams[name] = through.obj(function (chunk, enc, cb) {
-      mx.push({
-        name: name,
-        data: chunk,
-      })
-      return cb()
-    })
-    mx.on('end', function () {
-      return substream.emit('end')
-    })
-    if (opts.error) {
-      mx.on('error', function () {
-        return substream.emit('error')
-      })
-    }
-    return substream
-  }
-  // ignore streams (dont display orphaned data warning)
-  mx.ignoreStream = function (name) {
-    mx.streams[name] = true
-  }
-  return mx
-}
diff --git a/app/scripts/lib/port-stream.js b/app/scripts/lib/port-stream.js
index 607a9c9ed..648d88087 100644
--- a/app/scripts/lib/port-stream.js
+++ b/app/scripts/lib/port-stream.js
@@ -1,5 +1,6 @@
 const Duplex = require('readable-stream').Duplex
 const inherits = require('util').inherits
+const noop = function(){}
 
 module.exports = PortDuplexStream
 
@@ -20,20 +21,14 @@ PortDuplexStream.prototype._onMessage = function (msg) {
   if (Buffer.isBuffer(msg)) {
     delete msg._isBuffer
     var data = new Buffer(msg)
-    // console.log('PortDuplexStream - saw message as buffer', data)
     this.push(data)
   } else {
-    // console.log('PortDuplexStream - saw message', msg)
     this.push(msg)
   }
 }
 
 PortDuplexStream.prototype._onDisconnect = function () {
-  try {
-    this.push(null)
-  } catch (err) {
-    this.emit('error', err)
-  }
+  this.destroy()
 }
 
 // stream plumbing
@@ -45,19 +40,12 @@ PortDuplexStream.prototype._write = function (msg, encoding, cb) {
     if (Buffer.isBuffer(msg)) {
       var data = msg.toJSON()
       data._isBuffer = true
-      // console.log('PortDuplexStream - sent message as buffer', data)
       this._port.postMessage(data)
     } else {
-      // console.log('PortDuplexStream - sent message', msg)
       this._port.postMessage(msg)
     }
   } catch (err) {
-    // console.error(err)
     return cb(new Error('PortDuplexStream - disconnected'))
   }
   cb()
 }
-
-// util
-
-function noop () {}
diff --git a/app/scripts/lib/stream-utils.js b/app/scripts/lib/stream-utils.js
index ba79990cc..8bb0b4f3c 100644
--- a/app/scripts/lib/stream-utils.js
+++ b/app/scripts/lib/stream-utils.js
@@ -1,6 +1,6 @@
 const Through = require('through2')
-const endOfStream = require('end-of-stream')
-const ObjectMultiplex = require('./obj-multiplex')
+const ObjectMultiplex = require('obj-multiplex')
+const pump = require('pump')
 
 module.exports = {
   jsonParseStream: jsonParseStream,
@@ -23,14 +23,14 @@ function jsonStringifyStream () {
 }
 
 function setupMultiplex (connectionStream) {
-  var mx = ObjectMultiplex()
-  connectionStream.pipe(mx).pipe(connectionStream)
-  endOfStream(mx, function (err) {
-    if (err) console.error(err)
-  })
-  endOfStream(connectionStream, function (err) {
-    if (err) console.error(err)
-    mx.destroy()
-  })
-  return mx
+  const mux = new ObjectMultiplex()
+  pump(
+    connectionStream,
+    mux,
+    connectionStream,
+    (err) => {
+      if (err) console.error(err)
+    }
+  )
+  return mux
 }
diff --git a/app/scripts/metamask-controller.js b/app/scripts/metamask-controller.js
index a007d6fc5..fef16c3a9 100644
--- a/app/scripts/metamask-controller.js
+++ b/app/scripts/metamask-controller.js
@@ -1,12 +1,18 @@
 const EventEmitter = require('events')
 const extend = require('xtend')
 const promiseToCallback = require('promise-to-callback')
-const pipe = require('pump')
+const pump = require('pump')
 const Dnode = require('dnode')
 const ObservableStore = require('obs-store')
 const EthStore = require('./lib/eth-store')
 const EthQuery = require('eth-query')
-const streamIntoProvider = require('web3-stream-provider/handler')
+const RpcEngine = require('json-rpc-engine')
+const debounce = require('debounce')
+const createEngineStream = require('json-rpc-middleware-stream/engineStream')
+const createFilterMiddleware = require('eth-json-rpc-filters')
+const createOriginMiddleware = require('./lib/createOriginMiddleware')
+const createLoggerMiddleware = require('./lib/createLoggerMiddleware')
+const createProviderMiddleware = require('./lib/createProviderMiddleware')
 const setupMultiplex = require('./lib/stream-utils.js').setupMultiplex
 const KeyringController = require('./keyring-controller')
 const NetworkController = require('./controllers/network')
@@ -24,8 +30,6 @@ const ConfigManager = require('./lib/config-manager')
 const nodeify = require('./lib/nodeify')
 const accountImporter = require('./account-import-strategies')
 const getBuyEthUrl = require('./lib/buy-eth-url')
-const debounce = require('debounce')
-
 const version = require('../manifest.json').version
 
 module.exports = class MetamaskController extends EventEmitter {
@@ -77,12 +81,13 @@ module.exports = class MetamaskController extends EventEmitter {
 
     // rpc provider
     this.provider = this.initializeProvider()
+    this.blockTracker = this.provider
 
     // eth data query tools
     this.ethQuery = new EthQuery(this.provider)
     this.ethStore = new EthStore({
       provider: this.provider,
-      blockTracker: this.provider,
+      blockTracker: this.blockTracker,
     })
 
     // key mgmt
@@ -109,7 +114,7 @@ module.exports = class MetamaskController extends EventEmitter {
       getNetwork: this.networkController.getNetworkState.bind(this),
       signTransaction: this.keyringController.signTransaction.bind(this.keyringController),
       provider: this.provider,
-      blockTracker: this.provider,
+      blockTracker: this.blockTracker,
       ethQuery: this.ethQuery,
       ethStore: this.ethStore,
     })
@@ -337,36 +342,43 @@ module.exports = class MetamaskController extends EventEmitter {
   setupUntrustedCommunication (connectionStream, originDomain) {
     // Check if new connection is blacklisted
     if (this.blacklistController.checkForPhishing(originDomain)) {
-      console.log('MetaMask - sending phishing warning for', originDomain)
+      log.debug('MetaMask - sending phishing warning for', originDomain)
       this.sendPhishingWarning(connectionStream, originDomain)
       return
     }
 
     // setup multiplexing
-    const mx = setupMultiplex(connectionStream)
+    const mux = setupMultiplex(connectionStream)
     // connect features
-    this.setupProviderConnection(mx.createStream('provider'), originDomain)
-    this.setupPublicConfig(mx.createStream('publicConfig'))
+    this.setupProviderConnection(mux.createStream('provider'), originDomain)
+    this.setupPublicConfig(mux.createStream('publicConfig'))
   }
 
   setupTrustedCommunication (connectionStream, originDomain) {
     // setup multiplexing
-    const mx = setupMultiplex(connectionStream)
+    const mux = setupMultiplex(connectionStream)
     // connect features
-    this.setupControllerConnection(mx.createStream('controller'))
-    this.setupProviderConnection(mx.createStream('provider'), originDomain)
+    this.setupControllerConnection(mux.createStream('controller'))
+    this.setupProviderConnection(mux.createStream('provider'), originDomain)
   }
 
   sendPhishingWarning (connectionStream, hostname) {
-    const mx = setupMultiplex(connectionStream)
-    const phishingStream = mx.createStream('phishing')
+    const mux = setupMultiplex(connectionStream)
+    const phishingStream = mux.createStream('phishing')
     phishingStream.write({ hostname })
   }
 
   setupControllerConnection (outStream) {
     const api = this.getApi()
     const dnode = Dnode(api)
-    outStream.pipe(dnode).pipe(outStream)
+    pump(
+      outStream,
+      dnode,
+      outStream,
+      (err) => {
+        if (err) log.error(err)
+      }
+    )
     dnode.on('remote', (remote) => {
       // push updates to popup
       const sendUpdate = remote.sendUpdate.bind(remote)
@@ -374,27 +386,42 @@ module.exports = class MetamaskController extends EventEmitter {
     })
   }
 
-  setupProviderConnection (outStream, originDomain) {
-    streamIntoProvider(outStream, this.provider, onRequest, onResponse)
-    // append dapp origin domain to request
-    function onRequest (request) {
-      request.origin = originDomain
-    }
-    // log rpc activity
-    function onResponse (err, request, response) {
-      if (err) return console.error(err)
-      if (response.error) {
-        console.error('Error in RPC response:\n', response)
+  setupProviderConnection (outStream, origin) {
+    // setup json rpc engine stack
+    const engine = new RpcEngine()
+
+    // create filter polyfill middleware
+    const filterMiddleware = createFilterMiddleware({
+      provider: this.provider,
+      blockTracker: this.blockTracker,
+    })
+
+    engine.push(createOriginMiddleware({ origin }))
+    engine.push(createLoggerMiddleware({ origin }))
+    engine.push(filterMiddleware)
+    engine.push(createProviderMiddleware({ provider: this.provider }))
+
+    // setup connection
+    const providerStream = createEngineStream({ engine })
+    pump(
+      outStream,
+      providerStream,
+      outStream,
+      (err) => {
+        // cleanup filter polyfill middleware
+        filterMiddleware.destroy()
+        if (err) log.error(err)
       }
-      if (request.isMetamaskInternal) return
-      log.info(`RPC (${originDomain}):`, request, '->', response)
-    }
+    )
   }
 
   setupPublicConfig (outStream) {
-    pipe(
+    pump(
       this.publicConfigStore,
-      outStream
+      outStream,
+      (err) => {
+        if (err) log.error(err)
+      }
     )
   }
 
diff --git a/package.json b/package.json
index 12f79ba35..3f9d9c538 100644
--- a/package.json
+++ b/package.json
@@ -68,6 +68,7 @@
     "eth-bin-to-ops": "^1.0.1",
     "eth-contract-metadata": "^1.1.4",
     "eth-hd-keyring": "^1.1.1",
+    "eth-json-rpc-filters": "^1.1.0",
     "eth-phishing-detect": "^1.1.4",
     "eth-query": "^2.1.2",
     "eth-sig-util": "^1.2.2",
@@ -92,12 +93,15 @@
     "iframe-stream": "^3.0.0",
     "inject-css": "^0.1.1",
     "jazzicon": "^1.2.0",
+    "json-rpc-engine": "^3.1.0",
+    "json-rpc-middleware-stream": "^1.0.0",
     "loglevel": "^1.4.1",
     "metamask-logo": "^2.1.2",
     "mississippi": "^1.2.0",
     "mkdirp": "^0.5.1",
     "multiplex": "^6.7.0",
     "number-to-bn": "^1.7.0",
+    "obj-multiplex": "^1.0.0",
     "obs-store": "^2.3.1",
     "once": "^1.3.3",
     "ping-pong-stream": "^1.0.0",
@@ -118,7 +122,7 @@
     "react-select": "^1.0.0-rc.2",
     "react-simple-file-input": "^1.0.0",
     "react-tooltip-component": "^0.3.0",
-    "readable-stream": "^2.1.2",
+    "readable-stream": "^2.3.3",
     "redux": "^3.0.5",
     "redux-logger": "^3.0.6",
     "redux-thunk": "^2.2.0",
diff --git a/ui/app/components/pending-tx.js b/ui/app/components/pending-tx.js
index 3e53d47f9..c3350fcc1 100644
--- a/ui/app/components/pending-tx.js
+++ b/ui/app/components/pending-tx.js
@@ -52,7 +52,9 @@ PendingTx.prototype.render = function () {
   const gas = txParams.gas
   const gasBn = hexToBn(gas)
   const gasLimit = new BN(parseInt(blockGasLimit))
-  const safeGasLimit = this.bnMultiplyByFraction(gasLimit, 19, 20).toString(10)
+  const safeGasLimitBN = this.bnMultiplyByFraction(gasLimit, 19, 20)
+  const saferGasLimitBN = this.bnMultiplyByFraction(gasLimit, 18, 20)
+  const safeGasLimit = safeGasLimitBN.toString(10)
 
   // Gas Price
   const gasPrice = txParams.gasPrice || MIN_GAS_PRICE_BN.toString(16)
@@ -66,6 +68,8 @@ PendingTx.prototype.render = function () {
 
   const balanceBn = hexToBn(balance)
   const insufficientBalance = balanceBn.lt(maxCost)
+  const dangerousGasLimit = gasBn.gte(saferGasLimitBN)
+  const gasLimitSpecified = txMeta.gasLimitSpecified
   const buyDisabled = insufficientBalance || !this.state.valid || !isValidAddress || this.state.submitting
   const showRejectAll = props.unconfTxListLength > 1
 
@@ -263,33 +267,44 @@ PendingTx.prototype.render = function () {
             text-transform: uppercase;
           }
         `),
+        h('.cell.row', {
+          style: {
+            textAlign: 'center',
+          },
+        }, [
+          txMeta.simulationFails ?
+            h('.error', {
+              style: {
+                fontSize: '0.9em',
+              },
+            }, 'Transaction Error. Exception thrown in contract code.')
+          : null,
 
-        txMeta.simulationFails ?
-          h('.error', {
-            style: {
-              marginLeft: 50,
-              fontSize: '0.9em',
-            },
-          }, 'Transaction Error. Exception thrown in contract code.')
-        : null,
+          !isValidAddress ?
+            h('.error', {
+              style: {
+                fontSize: '0.9em',
+              },
+            }, 'Recipient address is invalid. Sending this transaction will result in a loss of ETH.')
+          : null,
 
-        !isValidAddress ?
-          h('.error', {
-            style: {
-              marginLeft: 50,
-              fontSize: '0.9em',
-            },
-          }, 'Recipient address is invalid. Sending this transaction will result in a loss of ETH.')
-        : null,
+          insufficientBalance ?
+            h('span.error', {
+              style: {
+                fontSize: '0.9em',
+              },
+            }, 'Insufficient balance for transaction')
+          : null,
+
+          (dangerousGasLimit && !gasLimitSpecified) ?
+            h('span.error', {
+              style: {
+                fontSize: '0.9em',
+              },
+            }, 'Gas limit set dangerously high. Approving this transaction is likely to fail.')
+          : null,
+        ]),
 
-        insufficientBalance ?
-          h('span.error', {
-            style: {
-              marginLeft: 50,
-              fontSize: '0.9em',
-            },
-          }, 'Insufficient balance for transaction')
-        : null,
 
         // send + cancel
         h('.flex-row.flex-space-around.conf-buttons', {