refactor(@embark/blockchain_process): remove http-proxy-middleware

The problems described in embark PR #1166 can be resolved by implementing the
blockchain proxy with `http-proxy` directly instead of using `express` together
with `http-proxy-middleware`. The ultimate cause of the buggy behavior (the
"stuck sockets" problems described in #1166) is unknown.

The need to swallow some errors as described in embark PR #1181 is also
eliminated by dropping `http-proxy-middleware` and `express`.

package.json

@@ -118,7 +118,7 @@
     "hard-source-webpack-plugin": "0.12.0",
     "helmet": "3.13.0",
     "hosted-git-info": "2.7.1",
-    "http-proxy-middleware": "0.19.0",
+    "http-proxy": "1.17.0",
     "http-shutdown": "1.2.0",
     "i18n": "0.8.3",
     "ipfs-api": "17.2.4",

src/lib/modules/blockchain_process/proxy.js

@@ -3,9 +3,9 @@
 const Asm = require('stream-json/Assembler');
 const {canonicalHost, defaultHost} = require('../../utils/host');
 const constants = require('../../constants.json');
-const express = require('express');
+const http = require('http');
+const httpProxy = require('http-proxy');
 const {parser: jsonParser} = require('stream-json');
-const proxyMiddleware = require('http-proxy-middleware');
 const pump = require('pump');
 const utils = require('../../utils/utils');
 const WsParser = require('simples/lib/parsers/ws');
@@ -17,21 +17,17 @@ const hex = (n) => {
 
 const parseJsonMaybe = (string) => {
   let object;
-  if (typeof string === 'string') {
-    // ignore empty strings
-    if (string) {
-      try {
-        object = JSON.parse(string);
-      } catch(e) {
-        // ignore client/server byte sequences sent when connections are closing
-        if (Array.from(Buffer.from(string)).map(hex).join(':') !==
-            '03:ef:bf:bd') {
-          console.error(`Proxy: Error parsing string as JSON '${string}'`);
-        }
+  // ignore empty strings
+  if (string !== '') {
+    try {
+      object = JSON.parse(string);
+    } catch(e) {
+      // ignore client/server byte sequences sent when connections are closing
+      if (Array.from(Buffer.from(string)).map(hex).join(':') !==
+          '03:ef:bf:bd') {
+        console.error(`Proxy: Error parsing string as JSON '${string}'`);
       }
     }
-  } else {
-    console.error(`Proxy: Expected a string but got type '${typeof string}'`);
   }
   return object;
 };
@@ -119,78 +115,75 @@ exports.serve = async (ipc, host, port, ws, origin, certOptions={}) => {
     });
   }());
 
-  const proxyOpts = {
-    logLevel: 'warn',
-    target: `http://${canonicalHost(host)}:${port}`,
-    ws: ws,
+  let proxy = httpProxy.createProxyServer({
     ssl: certOptions,
-
-    onError(err, _req, _res) {
-      console.error(
-        __('Proxy: Error forwarding requests to blockchain/simulator'),
-        err.message
-      );
+    target: {
+      host: canonicalHost(host),
+      port: port
     },
+    ws: ws
+  });
 
-    onProxyReq(_proxyReq, req, _res) {
-      if (req.method === 'POST') {
-        // messages TO the target
-        Asm.connectTo(
-          pump(req, jsonParser())
-        ).on('done', ({current: object}) => {
-          trackRequest(object);
-        });
-      }
-    },
+  proxy.on('error', (err) => {
+    console.error(
+      __('Proxy: Error forwarding requests to blockchain/simulator'),
+      err.message
+    );
+  });
 
-    onProxyRes(proxyRes, req, _res) {
-      if (req.method === 'POST') {
-        // messages FROM the target
-        Asm.connectTo(
-          pump(proxyRes, jsonParser())
-        ).on('done', ({current: object}) => {
-          trackResponse(object);
-        });
-      }
+  proxy.on('proxyRes', (proxyRes, req, _res) => {
+    if (req.method === 'POST') {
+      // messages FROM the target
+      Asm.connectTo(
+        pump(proxyRes, jsonParser())
+      ).on('done', ({current: object}) => {
+        trackResponse(object);
+      });
     }
-  };
+  });
 
-  if (ws) {
-    proxyOpts.onProxyReqWs = (_proxyReq, _req, socket, _options, _head) => {
+  const server = http.createServer((req, res) => {
+    if (req.method === 'POST') {
       // messages TO the target
-      pump(socket, new WsParser(0, false)).on('frame', ({data: buffer}) => {
-        const object = parseJsonMaybe(buffer.toString());
+      Asm.connectTo(
+        pump(req, jsonParser())
+      ).on('done', ({current: object}) => {
         trackRequest(object);
       });
-    };
+    }
 
-    proxyOpts.onOpen = (proxySocket) => {
+    if (!ws) {
+      proxy.web(req, res);
+    }
+  });
+
+  if (ws) {
+    server.on('upgrade', function (msg, socket, head) {
+      proxy.ws(msg, socket, head);
+    });
+
+    proxy.on('open', (proxySocket) => {
       // messages FROM the target
       pump(proxySocket, new WsParser(0, true)).on('frame', ({data: buffer}) => {
         const object = parseJsonMaybe(buffer.toString());
         trackResponse(object);
       });
-    };
+    });
+
+    proxy.on('proxyReqWs', (_proxyReq, _req, socket) => {
+      // messages TO the target
+      pump(socket, new WsParser(0, false)).on('frame', ({data: buffer}) => {
+        const object = parseJsonMaybe(buffer.toString());
+        trackRequest(object);
+      });
+    });
   }
 
-  const proxy = proxyMiddleware(proxyOpts);
-  const app = express();
-  app.use('*', proxy);
-
   return new Promise(resolve => {
-    const server = app.listen(
+    server.listen(
       port - constants.blockchain.servicePortOnProxy,
       defaultHost,
       () => { resolve(server); }
     );
-    if (ws) {
-      server.on('upgrade', (msg, socket, head) => {
-        const swallowError = (err) => {
-          console.error(`Proxy: Network error '${err.message}'`);
-        };
-        socket.on('error', swallowError);
-        proxy.upgrade(msg, socket, head);
-      });
-    }
   });
 };

yarn.lock

@@ -4965,17 +4965,7 @@ http-https@^1.0.0:
   resolved "https://registry.yarnpkg.com/http-https/-/http-https-1.0.0.tgz#2f908dd5f1db4068c058cd6e6d4ce392c913389b"
   integrity sha1-L5CN1fHbQGjAWM1ubUzjkskTOJs=
 
-http-proxy-middleware@0.19.0:
-  version "0.19.0"
-  resolved "https://registry.yarnpkg.com/http-proxy-middleware/-/http-proxy-middleware-0.19.0.tgz#40992b5901dc44bc7bc3795da81b0b248eca02d8"
-  integrity sha512-Ab/zKDy2B0404mz83bgki0HHv/xqpYKAyFXhopAiJaVAUSJfLYrpBYynTl4ZSUJ7TqrAgjarTsxdX5yBb4unRQ==
-  dependencies:
-    http-proxy "^1.17.0"
-    is-glob "^4.0.0"
-    lodash "^4.17.10"
-    micromatch "^3.1.10"
-
-http-proxy@^1.17.0:
+http-proxy@1.17.0:
   version "1.17.0"
   resolved "https://registry.yarnpkg.com/http-proxy/-/http-proxy-1.17.0.tgz#7ad38494658f84605e2f6db4436df410f4e5be9a"
   integrity sha512-Taqn+3nNvYRfJ3bGvKfBSRwy1v6eePlm3oc/aWVxZp57DQr5Eq3xhKJi7Z4hZpS8PC3H4qI+Yly5EmFacGuA/g==