fix: disable cors by default (#3275)

Co-authored-by: Marcin Rataj <lidel@lidel.org> Brings js-ipfs into line with go-ipfs by not having CORS on by default, instead requiring the user to explicitly configure it. BREAKING CHANGE: - CORS origins will need to be [configured manually](https://github.com/ipfs/js-ipfs/blob/master/packages/ipfs-http-client/README.md#cors) before use with ipfs-http-client
ipfs · Sep 14, 2020 · 3ff833d · 3ff833d
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diff --git a/docs/CONFIG.md b/docs/CONFIG.md
@@ -25,6 +25,13 @@ The js-ipfs config file is a JSON document located in the root directory of the
   - [`Enabled`](#enabled)
 - [`Swarm`](#swarm-1)
   - [`ConnMgr`](#connmgr)
+  - [Example](#example)
+- [`API`](#api-1)
+  - [`HTTPHeaders`](#httpheaders)
+    - [`Access-Control-Allow-Origin`](#access-control-allow-origin)
+      - [Example](#example-1)
+    - [`Access-Control-Allow-Credentials`](#access-control-allow-credentials)
+      - [Example](#example-2)
 
 ## Profiles
 
@@ -264,3 +271,55 @@ The "basic" connection manager tries to keep between `LowWater` and `HighWater`
   }
 }
 ```
+
+## `API`
+
+Settings applied to the HTTP RPC API server
+
+### `HTTPHeaders`
+
+HTTP header settings used by the HTTP RPC API server
+
+#### `Access-Control-Allow-Origin`
+
+The RPC API endpoints running on your local node are protected by the [Cross-Origin Resource Sharing](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS) mechanism.
+
+When a request is made that sends an `Origin` header, that Origin must be present in the allowed origins configured for the node, otherwise the browser will disallow that request to proceed, unless `mode: 'no-cors'` is set on the request, in which case the response will be opaque.
+
+To allow requests from web browsers, configure the `API.HTTPHeaders.Access-Control-Allow-Origin` setting.  This is an array of URL strings with safelisted Origins.
+
+##### Example
+
+If you are running a webapp locally that you access via the URL `http://127.0.0.1:3000`, you must add it to the list of allowed origins in order to make API requests from that webapp in the browser:
+
+```json
+{
+  "API": {
+    "HTTPHeaders": {
+      "Access-Control-Allow-Origin": [
+        "http://127.0.0.1:3000"
+      ]
+    }
+  }
+}
+```
+
+Note that the origin must match exactly so `'http://127.0.0.1:3000'` is treated differently to `'http://127.0.0.1:3000/'`
+
+#### `Access-Control-Allow-Credentials`
+
+The [Access-Control-Allow-Credentials](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Credentials) header allows client-side JavaScript running in the browser to send and receive credentials with requests - cookies, auth headers or TLS certificates.
+
+For most applications this will not be necessary but if you require this to be set, see the example below for how to configure it.
+
+##### Example
+
+```json
+{
+  "API": {
+    "HTTPHeaders": {
+      "Access-Control-Allow-Credentials": true
+    }
+  }
+}
+```
diff --git a/packages/ipfs-http-client/README.md b/packages/ipfs-http-client/README.md
@@ -342,6 +342,8 @@ $ ipfs config --json API.HTTPHeaders.Access-Control-Allow-Origin  '["http://exam
 $ ipfs config --json API.HTTPHeaders.Access-Control-Allow-Methods '["PUT", "POST", "GET"]'
 ```
 
+If you are using `js-ipfs`, substitute `ipfs` for `jsipfs` in the commands above.
+
 ### Custom Headers
 
 If you wish to send custom headers with each request made by this library, for example, the Authorization header. You can use the config to do so:

diff --git a/packages/ipfs/src/http/api/routes/index.js b/packages/ipfs/src/http/api/routes/index.js
@@ -1,16 +1,5 @@
 'use strict'
 
-const Boom = require('@hapi/boom')
-
-// RPC API requires POST, we block every other method
-const BLOCKED_METHODS = [
-  'GET',
-  'PUT',
-  'PATCH',
-  'DELETE',
-  'OPTIONS'
-]
-
 const routes = [
   require('./version'),
   require('./shutdown'),
@@ -40,19 +29,4 @@ const routes = [
 // webui is loaded from API port, but works over GET (not a part of RPC API)
 const extraRoutes = [...require('./webui')]
 
-const handler = () => {
-  throw Boom.methodNotAllowed()
-}
-
-// add routes that return HTTP 504 for non-POST requests to RPC API
-BLOCKED_METHODS.forEach(method => {
-  routes.forEach(route => {
-    extraRoutes.push({
-      method,
-      handler,
-      path: route.path
-    })
-  })
-})
-
 module.exports = routes.concat(extraRoutes)
diff --git a/packages/ipfs/src/http/error-handler.js b/packages/ipfs/src/http/error-handler.js
@@ -39,10 +39,18 @@ module.exports = server => {
       server.logger.error(res)
     }
 
-    return h.response({
+    const response = h.response({
       Message: message,
       Code: code,
       Type: 'error'
     }).code(statusCode)
+
+    const headers = res.output.headers || {}
+
+    Object.keys(headers).forEach(header => {
+      response.header(header, headers[header])
+    })
+
+    return response
   })
 }
diff --git a/packages/ipfs/src/http/index.js b/packages/ipfs/src/http/index.js
@@ -25,15 +25,15 @@ function hapiInfoToMultiaddr (info) {
   return toMultiaddr(uri)
 }
 
-async function serverCreator (serverAddrs, createServer, ipfs) {
+async function serverCreator (serverAddrs, createServer, ipfs, cors) {
   serverAddrs = serverAddrs || []
   // just in case the address is just string
   serverAddrs = Array.isArray(serverAddrs) ? serverAddrs : [serverAddrs]
 
   const servers = []
   for (const address of serverAddrs) {
     const addrParts = address.split('/')
-    const server = await createServer(addrParts[2], addrParts[4], ipfs)
+    const server = await createServer(addrParts[2], addrParts[4], ipfs, cors)
     await server.start()
     server.info.ma = hapiInfoToMultiaddr(server.info)
     servers.push(server)
@@ -56,9 +56,14 @@ class HttpApi {
 
     const config = await ipfs.config.getAll()
     config.Addresses = config.Addresses || {}
+    config.API = config.API || {}
+    config.API.HTTPHeaders = config.API.HTTPHeaders || {}
 
     const apiAddrs = config.Addresses.API
-    this._apiServers = await serverCreator(apiAddrs, this._createApiServer, ipfs)
+    this._apiServers = await serverCreator(apiAddrs, this._createApiServer, ipfs, {
+      origin: config.API.HTTPHeaders['Access-Control-Allow-Origin'] || [],
+      credentials: Boolean(config.API.HTTPHeaders['Access-Control-Allow-Credentials'])
+    })
 
     const gatewayAddrs = config.Addresses.Gateway
     this._gatewayServers = await serverCreator(gatewayAddrs, this._createGatewayServer, ipfs)
@@ -67,14 +72,22 @@ class HttpApi {
     return this
   }
 
-  async _createApiServer (host, port, ipfs) {
+  async _createApiServer (host, port, ipfs, cors) {
+    cors = {
+      ...cors,
+      additionalHeaders: ['X-Stream-Output', 'X-Chunked-Output', 'X-Content-Length'],
+      additionalExposedHeaders: ['X-Stream-Output', 'X-Chunked-Output', 'X-Content-Length']
+    }
+
+    if (!cors.origin || !cors.origin.length) {
+      cors = false
+    }
+
     const server = Hapi.server({
       host,
       port,
-      // CORS is enabled by default
-      // TODO: shouldn't, fix this
       routes: {
-        cors: true,
+        cors,
         response: {
           emptyStatusCode: 200
         }
@@ -95,6 +108,34 @@ class HttpApi {
       }
     })
 
+    // block all non-post or non-options requests
+    server.ext({
+      type: 'onRequest',
+      method: function (request, h) {
+        if (request.method === 'post' || request.method === 'options') {
+          return h.continue
+        }
+
+        if (request.method === 'get' && (request.path.startsWith('/ipfs') || request.path.startsWith('/webui'))) {
+          // allow requests to the webui
+          return h.continue
+        }
+
+        throw Boom.methodNotAllowed()
+      }
+    })
+
+    // https://tools.ietf.org/html/rfc7231#section-6.5.5
+    server.ext('onPreResponse', (request, h) => {
+      const { response } = request
+
+      if (response.isBoom && response.output && response.output.statusCode === 405) {
+        response.output.headers.Allow = 'OPTIONS, POST'
+      }
+
+      return h.continue
+    })
+
     // https://github.com/ipfs/go-ipfs-cmds/pull/193/files
     server.ext({
       type: 'onRequest',
@@ -144,24 +185,6 @@ class HttpApi {
       }
     })
 
-    const setHeader = (key, value) => {
-      server.ext('onPreResponse', (request, h) => {
-        const { response } = request
-        if (response.isBoom) {
-          response.output.headers[key] = value
-        } else {
-          response.header(key, value)
-        }
-        return h.continue
-      })
-    }
-
-    // Set default headers
-    setHeader('Access-Control-Allow-Headers',
-      'X-Stream-Output, X-Chunked-Output, X-Content-Length')
-    setHeader('Access-Control-Expose-Headers',
-      'X-Stream-Output, X-Chunked-Output, X-Content-Length')
-
     server.route(require('./api/routes'))
 
     errorHandler(server)