feat: add bypass list, bypass local addresses and username/password to proxy setting (#1059)

* fix: use fs/promises for settings

This PR switches from synchronous operations with the 'fs' module to asynchronous operations with
the 'fs/promises' module. It also corrects a small error with hostname migration.

* fix: add missing merge function of default and current config

* feat: add bypass list, bypass local addresses and username/password to proxy setting

This PR adds more options to the proxy setting, like username/password authentication, bypass list
of domains and bypass local addresses. The UX is taken from *arrs.

* fix: add error handling for proxy creating

* fix: remove logs

server/utils/customProxyAgent.ts

@@ -0,0 +1,111 @@
+import type { ProxySettings } from '@server/lib/settings';
+import logger from '@server/logger';
+import type { Dispatcher } from 'undici';
+import { Agent, ProxyAgent, setGlobalDispatcher } from 'undici';
+
+export default async function createCustomProxyAgent(
+  proxySettings: ProxySettings
+) {
+  const defaultAgent = new Agent();
+
+  const skipUrl = (url: string) => {
+    const hostname = new URL(url).hostname;
+
+    if (proxySettings.bypassLocalAddresses && isLocalAddress(hostname)) {
+      return true;
+    }
+
+    for (const address of proxySettings.bypassFilter.split(',')) {
+      const trimmedAddress = address.trim();
+      if (!trimmedAddress) {
+        continue;
+      }
+
+      if (trimmedAddress.startsWith('*')) {
+        const domain = trimmedAddress.slice(1);
+        if (hostname.endsWith(domain)) {
+          return true;
+        }
+      } else if (hostname === trimmedAddress) {
+        return true;
+      }
+    }
+
+    return false;
+  };
+
+  const noProxyInterceptor = (
+    dispatch: Dispatcher['dispatch']
+  ): Dispatcher['dispatch'] => {
+    return (opts, handler) => {
+      const url = opts.origin?.toString();
+      return url && skipUrl(url)
+        ? defaultAgent.dispatch(opts, handler)
+        : dispatch(opts, handler);
+    };
+  };
+
+  const token =
+    proxySettings.user && proxySettings.password
+      ? `Basic ${Buffer.from(
+          `${proxySettings.user}:${proxySettings.password}`
+        ).toString('base64')}`
+      : undefined;
+
+  try {
+    const proxyAgent = new ProxyAgent({
+      uri:
+        (proxySettings.useSsl ? 'https://' : 'http://') +
+        proxySettings.hostname +
+        ':' +
+        proxySettings.port,
+      token,
+      interceptors: {
+        Client: [noProxyInterceptor],
+      },
+    });
+
+    setGlobalDispatcher(proxyAgent);
+  } catch (e) {
+    logger.error('Failed to connect to the proxy: ' + e.message, {
+      label: 'Proxy',
+    });
+    setGlobalDispatcher(defaultAgent);
+    return;
+  }
+
+  try {
+    const res = await fetch('https://www.google.com', { method: 'HEAD' });
+    if (res.ok) {
+      logger.debug('HTTP(S) proxy connected successfully', { label: 'Proxy' });
+    } else {
+      logger.error('Proxy responded, but with a non-OK status: ' + res.status, {
+        label: 'Proxy',
+      });
+      setGlobalDispatcher(defaultAgent);
+    }
+  } catch (e) {
+    logger.error(
+      'Failed to connect to the proxy: ' + e.message + ': ' + e.cause,
+      { label: 'Proxy' }
+    );
+    setGlobalDispatcher(defaultAgent);
+  }
+}
+
+function isLocalAddress(hostname: string) {
+  if (hostname === 'localhost' || hostname === '127.0.0.1') {
+    return true;
+  }
+
+  const privateIpRanges = [
+    /^10\./, // 10.x.x.x
+    /^172\.(1[6-9]|2[0-9]|3[0-1])\./, // 172.16.x.x - 172.31.x.x
+    /^192\.168\./, // 192.168.x.x
+  ];
+  if (privateIpRanges.some((regex) => regex.test(hostname))) {
+    return true;
+  }
+
+  return false;
+}