Improve response handling

* Better error handling for both RPC and REST calls.
  * Handle `text/html` and `text/plain` differences from both request
    types correctly.
  * Proxy response errors as error messages for easier debugging.
  * Add a test for batched requests where one of the request fails.
  * Handle errors in binary-encoded requests.
* Parse REST responses with JSONBigInt to avoid losing precision. This
  means that some of the response values will now be strings (e.g.
  the network difficulty on `getDifficulty()`).

Author: Pedro Branco

README.md

@@ -115,7 +115,7 @@ This feature is available to all JSON-RPC methods that accept arguments.
 
 ### Floating point number precision in JavaScript
 
-Due to [Javascript's limited floating point precision](http://floating-point-gui.de/), all big numbers (numbers with more than 15 significant digits) are returned as strings to prevent precision loss.
+Due to [JavaScript's limited floating point precision](http://floating-point-gui.de/), all big numbers (numbers with more than 15 significant digits) are returned as strings to prevent precision loss. This includes both the RPC and REST APIs.
 
 ### Version Checking
 By default, all methods are exposed on the client independently of the version it is connecting to. This is the most flexible option as defining methods for unavailable RPC calls does not cause any harm and the library is capable of handling a `Method not found` response error correctly.

src/index.js

@@ -101,7 +101,6 @@ class Client {
     this.request = Promise.promisifyAll(request.defaults({
       agentOptions: this.agentOptions,
       baseUrl: `${this.ssl.enabled ? 'https' : 'http'}://${this.host}:${this.port}`,
-      json: true,
       strictSSL: this.ssl.strict,
       timeout: this.timeout
     }), { multiArgs: true });
@@ -139,7 +138,6 @@ class Client {
       return this.request.postAsync({
         auth: _.pickBy(this.auth, _.identity),
         body: JSON.stringify(body),
-        json: false,
         uri: '/'
       }).bind(this)
         .then(this.parser.rpc);
@@ -158,7 +156,7 @@ class Client {
         encoding: extension === 'bin' ? null : undefined,
         url: `/rest/tx/${hash}.${extension}`
       }).bind(this)
-        .then(this.parser.rest);
+        .then(_.partial(this.parser.rest, extension));
     }).asCallback(callback);
   }
 
@@ -176,7 +174,7 @@ class Client {
         encoding: extension === 'bin' ? null : undefined,
         url: `/rest/block${summary ? '/notxdetails/' : '/'}${hash}.${extension}`
       }).bind(this)
-        .then(this.parser.rest);
+        .then(_.partial(this.parser.rest, extension));
     }).asCallback(callback);
   }
 
@@ -196,7 +194,7 @@ class Client {
         encoding: extension === 'bin' ? null : undefined,
         url: `/rest/headers/${count}/${hash}.${extension}`
       }).bind(this)
-        .then(this.parser.rest);
+        .then(_.partial(this.parser.rest, extension));
     }).asCallback(callback);
   }
 
@@ -210,7 +208,7 @@ class Client {
 
     return this.request.getAsync(`/rest/chaininfo.json`)
       .bind(this)
-      .then(this.parser.rest)
+      .then(_.partial(this.parser.rest, 'json'))
       .asCallback(callback);
   }
 
@@ -231,7 +229,7 @@ class Client {
       encoding: extension === 'bin' ? null : undefined,
       url: `/rest/getutxos/checkmempool/${sets}.${extension}`
     }).bind(this)
-      .then(this.parser.rest)
+      .then(_.partial(this.parser.rest, extension))
       .asCallback(callback);
   }
 
@@ -245,7 +243,7 @@ class Client {
 
     return this.request.getAsync('/rest/mempool/contents.json')
       .bind(this)
-      .then(this.parser.rest)
+      .then(_.partial(this.parser.rest, 'json'))
       .asCallback(callback);
   }
 
@@ -263,7 +261,7 @@ class Client {
 
     return this.request.getAsync('/rest/mempool/info.json')
       .bind(this)
-      .then(this.parser.rest)
+      .then(_.partial(this.parser.rest, 'json'))
       .asCallback(callback);
   }
 }

src/parser.js

@@ -14,21 +14,18 @@ import _ from 'lodash';
 const { parse } = JSONBigInt({ storeAsString: true, strict: true }); // eslint-disable-line new-cap
 
 /**
- * Get response result and errors.
+ * Get RPC response body result.
  */
 
-function get(body, { headers = false, response } = {}) {
-  if (!body) {
-    throw new RpcError(response.statusCode, response.statusMessage);
-  }
-
+function getRpcResult(body, { headers = false, response } = {}) {
   if (body.error !== null) {
     throw new RpcError(
       _.get(body, 'error.code', -32603),
       _.get(body, 'error.message', 'An error occurred while processing the RPC call to bitcoind')
     );
   }
 
+  // Defensive measure. This should not happen on a RPC call.
   if (!_.has(body, 'result')) {
     throw new RpcError(-32700, 'Missing `result` on the RPC call result');
   }
@@ -54,22 +51,23 @@ export default class Parser {
    */
 
   rpc([response, body]) {
-    // Body contains HTML (e.g. 401 Unauthorized).
-    if (typeof body === 'string' && response.statusCode !== 200) {
-      throw new RpcError(response.statusCode);
+    // The RPC api returns a `text/html; charset=ISO-8859-1` encoded response with an empty string as the body
+    // when an error occurs.
+    if (typeof body === 'string' && response.headers['content-type'] !== 'application/json' && response.statusCode !== 200) {
+      throw new RpcError(response.statusCode, response.statusMessage, { body });
     }
 
     // Parsing the body with custom parser to support BigNumbers.
     body = parse(body);
 
     if (!Array.isArray(body)) {
-      return get(body, { headers: this.headers, response });
+      return getRpcResult(body, { headers: this.headers, response });
     }
 
     // Batch response parsing where each response may or may not be successful.
     const batch = body.map(response => {
       try {
-        return get(response, { headers: false, response });
+        return getRpcResult(response, { headers: false, response });
       } catch (e) {
         return e;
       }
@@ -82,9 +80,22 @@ export default class Parser {
     return batch;
   }
 
-  rest([response, body]) {
-    if (body.error) {
-      throw new RpcError(body.error.code, body.error.message);
+  rest(extension, [response, body]) {
+    // The REST api returns a `text/plain` encoded response with the error line and the control
+    // characters \r\n. For readability and debuggability, the error message is set to this content.
+    // When requesting a binary response, the body will be returned as a Buffer representation of
+    // this error string.
+    if (response.headers['content-type'] !== 'application/json' && response.statusCode !== 200) {
+      if (body instanceof Buffer) {
+        body = body.toString('utf-8');
+      }
+
+      throw new RpcError(response.statusCode, body.replace('\r\n', ''), { body });
+    }
+
+    // Parsing the body with custom parser to support BigNumbers.
+    if (extension === 'json') {
+      body = parse(body);
     }
 
     if (this.headers) {

test/errors/rpc-error_test.js

@@ -3,8 +3,8 @@
  * Module dependencies.
  */
 
-import RpcError from '../../src/errors/rpc-error';
 import { STATUS_CODES } from 'http';
+import RpcError from '../../src/errors/rpc-error';
 import should from 'should';
 
 /**

test/index_test.js

@@ -105,8 +105,8 @@ describe('Client', () => {
       } catch (e) {
         e.should.be.an.instanceOf(RpcError);
         e.message.should.equal('Unauthorized');
+        e.body.should.equal('');
         e.code.should.equal(401);
-        e.status.should.equal(401);
       }
     });
 
@@ -133,9 +133,20 @@ describe('Client', () => {
 
       const [newAddress, addressValidation] = await new Client(config.bitcoind).command(batch);
 
-      addressValidation.should.have.properties('address', 'isvalid', 'ismine', 'scriptPubKey');
+      addressValidation.should.have.properties('address', 'ismine', 'isvalid', 'scriptPubKey');
       newAddress.should.be.a.String();
     });
+
+    it('should return an error if one of the request fails', async () => {
+      const batch = [{ method: 'foobar' }, { method: 'validateaddress', parameters: ['mkteeBFmGkraJaWN5WzqHCjmbQWVrPo5X3'] }];
+
+      const [newAddressError, addressValidation] = await new Client(config.bitcoind).command(batch);
+
+      addressValidation.should.have.properties('address', 'ismine', 'isvalid', 'scriptPubKey');
+      newAddressError.should.be.an.instanceOf(RpcError);
+      newAddressError.message.should.equal('Method not found');
+      newAddressError.code.should.equal(-32601);
+    });
   });
 
   describe('headers', () => {
@@ -615,5 +626,31 @@ describe('Client', () => {
         information.usage.should.be.a.Number();
       });
     });
+
+    it('should throw an error if a method contains invalid arguments', async () => {
+      try {
+        await new Client(config.bitcoind).getTransactionByHash('foobar');
+
+        should.fail();
+      } catch (e) {
+        e.should.be.an.instanceOf(RpcError);
+        e.body.should.equal('Invalid hash: foobar\r\n');
+        e.message.should.equal('Invalid hash: foobar');
+        e.code.should.equal(400);
+      }
+    });
+
+    it('should throw an error if a method in binary mode contains invalid arguments', async () => {
+      try {
+        await new Client(config.bitcoind).getTransactionByHash('foobar', { extension: 'bin' });
+
+        should.fail();
+      } catch (e) {
+        e.should.be.an.instanceOf(RpcError);
+        e.body.should.equal('Invalid hash: foobar\r\n');
+        e.message.should.equal('Invalid hash: foobar');
+        e.code.should.equal(400);
+      }
+    });
   });
 });