Use express-validator, refactor

api/package.json

@@ -10,6 +10,7 @@
   "author": "",
   "license": "ISC",
   "dependencies": {
-    "express": "^4.17.1"
+    "express": "^4.17.1",
+    "express-validator": "^6.9.2"
   }
 }

api/src/execute.js

@@ -0,0 +1,46 @@
+const { writeFile } = require('fs/promises');
+const { spawn } = require('child_process');
+
+async function execute(res, language, body) {
+    const stamp = new Date().getTime();
+    const sourceFile = `/tmp/${stamp}.code`;
+
+    await writeFile(sourceFile, body.source);
+
+    const process = spawn(__dirname + '/../../lxc/execute', [
+        language.name,
+        sourceFile,
+        body.args?.join('\n') ?? '',
+    ]);
+
+    const result = {
+        ran: true,
+        language: language.name,
+        stderr: '',
+        stdout: '',
+        output: '',
+    };
+
+    if (language.version)
+        result.version = language.version;
+
+    process.stderr.on('data', chunk => {
+        result.stderr += chunk;
+        result.output += chunk;
+    });
+
+    process.stdout.on('data', chunk => {
+        result.stdout += chunk;
+        result.output += chunk;
+    });
+
+    result.stderr = result.stderr.trim().substring(0, 65535);
+    result.stdout = result.stdout.trim().substring(0, 65535);
+    result.output = result.output.trim().substring(0, 65535);
+
+    process.on('exit', () => res.json(result));
+}
+
+module.exports = {
+    execute,
+};

api/src/index.js

@@ -1,110 +1,63 @@
-const { writeFile } = require('fs/promises');
 const express = require('express');
-const app = express();
-const languages = require('./languages');
-const { spawn } = require('child_process');
-
-{
-    const process = spawn(__dirname + '/../../lxc/versions');
-
-    let output = '';
-    process.stderr.on('data', chunk => output += chunk);
-    process.stdout.on('data', chunk => output += chunk);
-
-    process.on('exit', () => {
-        const sections = output.toLowerCase().split('---');
-        const versions = {};
-
-        for (const section of sections) {
-            const lines = section.trim().split('\n');
-            
-            if (lines.length >= 2) {
-                const language = lines[0];
-
-                if (language === 'java') {
-                    versions[language] = /\d+/.exec(lines[1])?.[0];
-                } else if (language === 'emacs') {
-                    versions[language] = /\d+\.\d+/.exec(lines[1])?.[0];
-                } else {
-                    versions[language] = /\d+\.\d+\.\d+/.exec(section)?.[0];
-                }
-            }
-        }
-
-        for (const language of languages) {
-            language.version = versions[language.name];
-        }
-    });
-}
-
-app.use(express.json());
-
-app.post('/execute', (req, res) => {
-    const body = req.body;
-
-    const language = languages.find(language => {
-        return language.aliases.includes(body.language?.toString()?.toLowerCase());
-    });
-
-    if (!language) {
-        return res.status(400).json({
-            code: 'unsupported_language',
-            message: `${body.language} is not supported by Piston`,
-        });
-    } else if (typeof body.source !== 'string') {
-        return res.status(400).json({
-            code: 'missing_source',
-            message: 'source field is invalid',
-        });
-    } else if (body.args && !Array.isArray(body.args)) {
-        return res.status(400).json({
-            code: 'invalid_args',
-            message: 'args field is not an array',
-        });
-    }
-
-    launch(res, language, body);
-});
-
-async function launch(res, language, body) {
-    const stamp = new Date().getTime();
-    const sourceFile = `/tmp/${stamp}.code`;
-
-    await writeFile(sourceFile, body.source);
-
-    const process = spawn(__dirname + '/../../lxc/execute', [language.name, sourceFile, (body.args ?? []).join('\n')]);
-
-    const result = {
-        ran: true,
-        language: language.name,
-        stderr: '',
-        stdout: '',
-        output: '',
-    };
-
-    if (language.version)
-        result.version = language.version;
-
-    process.stderr.addListener('data', chunk => {
-        result.stderr += chunk;
-        result.output += chunk;
-    });
-
-    process.stdout.addListener('data', chunk => {
-        result.stdout += chunk;
-        result.output += chunk;
-    });
-
-    result.stderr = result.stderr.trim().substring(0, 65535);
-    result.stdout = result.stdout.trim().substring(0, 65535);
-    result.output = result.output.trim().substring(0, 65535);
-
-    process.on('exit', () => res.json(result));
-}
-
-app.get('/versions', (req, res) => {
-    res.json(languages);
-});
+const { execute } = require('./execute');
+const { languages } = require('./languages');
+const { checkSchema, validationResult } = require('express-validator');
 
 const PORT = 2000;
+
+const app = express();
+app.use(express.json());
+
+app.post(
+    '/execute',
+    checkSchema({
+        language: {
+            in: 'body',
+            notEmpty: {
+                errorMessage: 'Supply a language field',
+            },
+            isString: {
+                errorMessage: 'Supplied language is not a string',
+            },
+            custom: {
+                options: value => languages.find(language => language.name === value?.toLowerCase()),
+                errorMessage: 'Supplied language is not supported by Piston',
+            },
+        },
+        source: {
+            in: 'body',
+            notEmpty: {
+                errorMessage: 'Supply a source field',
+            },
+            isString: {
+                errorMessage: 'Supplied source is not a string',
+            },
+        },
+        args: {
+            in: 'body',
+            optional: true,
+            isArray: {
+                errorMessage: 'Supplied args is not an array',
+            },
+        }
+    }),
+    (req, res) => {
+        const errors = validationResult(req).array();
+
+        if (errors.length === 0) {
+            const language = languages.find(language =>
+                language.aliases.includes(req.body.language.toLowerCase())
+            );
+
+            execute(res, language, req.body);
+        } else {
+            res.status(400).json({
+                message: errors[0].msg,
+            });
+        }
+    },
+);
+
+app.get('/versions', (_, res) => res.json(languages));
+
 app.listen(PORT, () => console.log(`Listening on port ${PORT}`));

api/src/languages.js

@@ -1,4 +1,6 @@
-module.exports = [
+const { spawn } = require('child_process');
+
+const languages = [
     {
         name: 'nasm',
         aliases: ['asm', 'nasm'],
@@ -112,3 +114,40 @@ module.exports = [
         aliases: ['ts', 'typescript'],
     },
 ];
+
+{
+    const process = spawn(__dirname + '/../../lxc/versions');
+
+    let output = '';
+    process.stderr.on('data', chunk => output += chunk);
+    process.stdout.on('data', chunk => output += chunk);
+
+    process.on('exit', () => {
+        const sections = output.toLowerCase().split('---');
+        const versions = {};
+
+        for (const section of sections) {
+            const lines = section.trim().split('\n');
+            
+            if (lines.length >= 2) {
+                const language = lines[0];
+
+                if (language === 'java') {
+                    versions[language] = /\d+/.exec(lines[1])?.[0];
+                } else if (language === 'emacs') {
+                    versions[language] = /\d+\.\d+/.exec(lines[1])?.[0];
+                } else {
+                    versions[language] = /\d+\.\d+\.\d+/.exec(section)?.[0];
+                }
+            }
+        }
+
+        for (const language of languages) {
+            language.version = versions[language.name];
+        }
+    });
+}
+
+module.exports = {
+    languages,
+};

lxc/execute

@@ -4,11 +4,7 @@ dir="$( cd "$( dirname "$0" )" && pwd )"
 
 touch $dir/lockfile
 
-if [ -z "$1" ]; then
-    echo "invalid args"
-    exit
-fi
-if [ -z "$2" ]; then
+if [ -z "$1" ] || [ -z "$2" ]; then
     echo "invalid args"
     exit
 fi

readme.md

@@ -167,7 +167,7 @@ Content-Type: application/json
 - typescript
 
 #### Principle of Operation
-Piston utilizes LXC as the primary mechanism for sandboxing. There is a small API written in Go which takes
+Piston utilizes LXC as the primary mechanism for sandboxing. There is a small API written in Node which takes
 in execution requests and executes them in the container. High level, the API writes
 a temporary source and args file to `/tmp` and that gets mounted read-only along with the execution scripts into the container.
 The source file is either ran or compiled and ran (in the case of languages like c, c++, c#, go, etc.).