feat: Add support for NO_PROXY

README.md

@@ -71,7 +71,7 @@ let defaultRequest = teenyRequest.defaults({timeout: 60000});
 ```        
 
 ## Proxy environment variables
-If environment variables `HTTP_PROXY` or `HTTPS_PROXY` are set, they are respected. `NO_PROXY` is currently not implemented.
+If environment variables `HTTP_PROXY`, `HTTPS_PROXY`, or `NO_PROXY` are set, they are respected.
 
 ## Building with Webpack 4+
 Since 4.0.0, Webpack uses `javascript/esm` for `.mjs` files which handles ESM more strictly compared to `javascript/auto`. If you get the error `Can't import the named export 'PassThrough' from non EcmaScript module`, please add the following to your Webpack config:

src/agents.ts

@@ -25,6 +25,37 @@ export const pool = new Map<string, HTTPAgent>();
 
 export type HttpAnyAgent = HTTPAgent | HTTPSAgent;
 
+/**
+ * Determines if a proxy should be considered based on the environment.
+ *
+ * @param uri The request uri
+ * @returns {boolean}
+ */
+function shouldUseProxyForURI(uri: string): boolean {
+  const noProxyEnv = process.env.NO_PROXY || process.env.no_proxy;
+  if (!noProxyEnv) {
+    return true;
+  }
+
+  const givenURI = new URL(uri);
+
+  for (const noProxyRaw of noProxyEnv.split(',')) {
+    const noProxy = noProxyRaw.trim();
+
+    if (noProxy === givenURI.origin || noProxy === givenURI.hostname) {
+      return false;
+    } else if (noProxy.startsWith('*.') || noProxy.startsWith('.')) {
+      const noProxyWildcard = noProxy.replace(/^\*\./, '.');
+
+      if (givenURI.hostname.endsWith(noProxyWildcard)) {
+        return false;
+      }
+    }
+  }
+
+  return true;
+}
+
 /**
  * Returns a custom request Agent if one is found, otherwise returns undefined
  * which will result in the global http(s) Agent being used.
@@ -47,7 +78,10 @@ export function getAgent(
 
   const poolOptions = Object.assign({}, reqOpts.pool);
 
-  if (proxy) {
+  const manuallyProvidedProxy = !!reqOpts.proxy;
+  const shouldUseProxy = manuallyProvidedProxy || shouldUseProxyForURI(uri);
+
+  if (proxy && shouldUseProxy) {
     // tslint:disable-next-line variable-name
     const Agent = isHttp
       ? require('http-proxy-agent')

test/agents.ts

@@ -53,6 +53,18 @@ describe('agents', () => {
         'HTTPS_PROXY',
       ];
 
+      const noProxyEnvVars = ['no_proxy', 'NO_PROXY'];
+
+      function cleanProxyEnv() {
+        for (const env of noProxyEnvVars) {
+          delete process.env[env];
+        }
+
+        for (const env of envVars) {
+          delete process.env[env];
+        }
+      }
+
       describe('http', () => {
         const uri = httpUri;
         const proxy = 'http://hello.there:8080';
@@ -114,6 +126,52 @@ describe('agents', () => {
           });
         });
       });
+
+      describe('no_proxy', () => {
+        const uri = httpsUri;
+        const proxy = 'https://hello.there:8080';
+
+        beforeEach(cleanProxyEnv);
+        afterEach(cleanProxyEnv);
+
+        noProxyEnvVars.forEach(noProxEnvVar => {
+          it(`should respect the proxy option, even if is in ${noProxEnvVar} env var`, () => {
+            process.env[noProxEnvVar] = new URL(uri).hostname;
+
+            const options = Object.assign({proxy}, defaultOptions);
+            const agent = getAgent(uri, options);
+            assert(agent instanceof HttpsProxyAgent);
+          });
+        });
+
+        noProxyEnvVars.forEach(noProxEnvVar => {
+          envVars.forEach(envVar => {
+            const root = 'example.com';
+            const subDomain = 'abc.' + root;
+
+            const uri = new URL(`https://${subDomain}`);
+
+            const cases = [
+              {name: '`.` support', value: `.${root}`},
+              {name: '`*.` support', value: `*.${root}`},
+              {name: 'list support', value: `a, b,${subDomain},.c,*.d`},
+              {name: '`.` + list support', value: `a, b,.${root},.c,*.d`},
+              {name: '`*.` + list support', value: `a, b,*.${root},.c,*.d`},
+            ];
+
+            for (const {name, value} of cases) {
+              it(`should respect the ${noProxEnvVar} env var > ${envVar}': ${name}`, () => {
+                process.env[envVar] = proxy;
+
+                process.env[noProxEnvVar] = value;
+                const agent = getAgent(uri.toString(), defaultOptions);
+                assert(!(agent instanceof HttpProxyAgent));
+                assert(!(agent instanceof HttpsProxyAgent));
+              });
+            }
+          });
+        });
+      });
     });
 
     describe('forever', () => {