Add web proxy support

README.md

@@ -111,12 +111,51 @@ For any MCP-compatible client, use:
 npx @perplexity-ai/mcp-server
 ```
 
+### Proxy Setup (For Corporate Networks)
+
+If you are running this server at work—especially behind a company firewall or proxy—you may need to tell the program how to send its internet traffic through your network's proxy. Follow these steps:
+
+**1. Get your proxy details**
+
+- Ask your IT department for your HTTP(S) proxy address and port.
+- You may also need a username and password.
+
+**2. Set the proxy environment variable**
+
+The easiest and most reliable way for Perplexity MCP is to use `PERPLEXITY_PROXY`. For example:
+
+```bash
+export PERPLEXITY_PROXY=http://your-proxy-host:8080
+```
+
+- If your proxy needs a username and password, use:
+  ```bash
+  export PERPLEXITY_PROXY=http://username:password@your-proxy-host:8080
+  ```
+
+**3. Alternate: Standard environment variables**
+
+If you'd rather use the standard variables, we support `HTTPS_PROXY` and `HTTP_PROXY`.
+
+> [!NOTE]
+>The server checks proxy settings in this order: `PERPLEXITY_PROXY` → `HTTPS_PROXY` → `HTTP_PROXY`. If none are set, it connects directly to the internet.
+
 ## Troubleshooting
 
 - **API Key Issues**: Ensure `PERPLEXITY_API_KEY` is set correctly
 - **Connection Errors**: Check your internet connection and API key validity
 - **Tool Not Found**: Make sure the package is installed and the command path is correct
 - **Timeout Errors**: For very long research queries, set `PERPLEXITY_TIMEOUT_MS` to a higher value
+- **Proxy Issues**: If you're behind a corporate firewall and experience connection errors, you likely need to set up a proxy:
+  - Obtain your proxy server address and port from your IT department.
+  - Set the environment variable before running the server, e.g.:
+    - `export PERPLEXITY_PROXY=http://proxy-address:port`
+    - If authentication is needed: `export PERPLEXITY_PROXY=http://username:password@proxy-address:port`
+    - Typical proxy ports include 8080, 3128, or 80.
+  - The format for authenticated proxies is:  
+    `http://username:password@proxy-host:port`
+  - Double-check the address, port, and credentials if connections fail or time out.
+  - If you continue to have issues, your firewall may be blocking traffic; ask IT if traffic for `api.perplexity.ai` is being restricted.
 
 For support, visit [community.perplexity.ai](https://community.perplexity.ai) or [file an issue](https://github.com/perplexityai/modelcontextprotocol/issues).
 

index.test.ts

@@ -665,4 +665,65 @@ describe("Perplexity MCP Server", () => {
       expect(resultKept).toContain("The answer is 4.");
     });
   });
+
+  describe("Proxy Support", () => {
+    const originalEnv = process.env;
+
+    beforeEach(() => {
+      // Reset environment variables
+      process.env = { ...originalEnv };
+      delete process.env.PERPLEXITY_PROXY;
+      delete process.env.HTTPS_PROXY;
+      delete process.env.HTTP_PROXY;
+    });
+
+    afterEach(() => {
+      process.env = originalEnv;
+    });
+
+    it("should use native fetch when no proxy is configured", async () => {
+      const mockResponse = {
+        choices: [{ message: { content: "Test response" } }],
+      };
+
+      global.fetch = vi.fn().mockResolvedValue({
+        ok: true,
+        json: async () => mockResponse,
+      } as Response);
+
+      const messages = [{ role: "user", content: "test" }];
+      await performChatCompletion(messages);
+
+      // Verify native fetch was called (not undici)
+      expect(global.fetch).toHaveBeenCalled();
+    });
+
+    it("should read PERPLEXITY_PROXY environment variable", () => {
+      process.env.PERPLEXITY_PROXY = "http://proxy.example.com:8080";
+      expect(process.env.PERPLEXITY_PROXY).toBe("http://proxy.example.com:8080");
+    });
+
+    it("should prioritize PERPLEXITY_PROXY over HTTPS_PROXY", () => {
+      process.env.PERPLEXITY_PROXY = "http://perplexity-proxy.example.com:8080";
+      process.env.HTTPS_PROXY = "http://https-proxy.example.com:8080";
+
+      // PERPLEXITY_PROXY should take precedence
+      expect(process.env.PERPLEXITY_PROXY).toBe("http://perplexity-proxy.example.com:8080");
+    });
+
+    it("should fall back to HTTPS_PROXY when PERPLEXITY_PROXY is not set", () => {
+      delete process.env.PERPLEXITY_PROXY;
+      process.env.HTTPS_PROXY = "http://https-proxy.example.com:8080";
+
+      expect(process.env.HTTPS_PROXY).toBe("http://https-proxy.example.com:8080");
+    });
+
+    it("should fall back to HTTP_PROXY when others are not set", () => {
+      delete process.env.PERPLEXITY_PROXY;
+      delete process.env.HTTPS_PROXY;
+      process.env.HTTP_PROXY = "http://http-proxy.example.com:8080";
+
+      expect(process.env.HTTP_PROXY).toBe("http://http-proxy.example.com:8080");
+    });
+  });
 });

index.ts

@@ -7,6 +7,7 @@ import {
   ListToolsRequestSchema,
   Tool,
 } from "@modelcontextprotocol/sdk/types.js";
+import { fetch as undiciFetch, ProxyAgent } from "undici";
 
 /**
  * Definition of the Perplexity Ask Tool.
@@ -169,6 +170,45 @@ if (!PERPLEXITY_API_KEY) {
   process.exit(1);
 }
 
+/**
+ * Gets the proxy URL from environment variables.
+ * Checks PERPLEXITY_PROXY, HTTPS_PROXY, HTTP_PROXY in order.
+ * 
+ * @returns {string | undefined} The proxy URL if configured, undefined otherwise
+ */
+function getProxyUrl(): string | undefined {
+  return process.env.PERPLEXITY_PROXY || 
+         process.env.HTTPS_PROXY || 
+         process.env.HTTP_PROXY || 
+         undefined;
+}
+
+/**
+ * Creates a proxy-aware fetch function.
+ * Uses undici with ProxyAgent when a proxy is configured, otherwise uses native fetch.
+ * 
+ * @param {string} url - The URL to fetch
+ * @param {RequestInit} options - Fetch options
+ * @returns {Promise<Response>} The fetch response
+ */
+async function proxyAwareFetch(url: string, options: RequestInit = {}): Promise<Response> {
+  const proxyUrl = getProxyUrl();
+
+  if (proxyUrl) {
+    // Use undici with ProxyAgent when proxy is configured
+    const proxyAgent = new ProxyAgent(proxyUrl);
+    const response = await undiciFetch(url, {
+      ...options,
+      dispatcher: proxyAgent,
+    } as any);
+    // Cast to native Response type for compatibility
+    return response as unknown as Response;
+  } else {
+    // Use native fetch when no proxy is configured
+    return fetch(url, options);
+  }
+}
+
 /**
  * Validates an array of message objects for chat completion tools.
  * Ensures each message has a valid role and content field.
@@ -240,7 +280,7 @@ export async function performChatCompletion(
 
   let response;
   try {
-    response = await fetch(url.toString(), {
+    response = await proxyAwareFetch(url.toString(), {
       method: "POST",
       headers: {
         "Content-Type": "application/json",
@@ -371,7 +411,7 @@ export async function performSearch(
 
   let response;
   try {
-    response = await fetch(url.toString(), {
+    response = await proxyAwareFetch(url.toString(), {
       method: "POST",
       headers: {
         "Content-Type": "application/json",

package.json

@@ -41,7 +41,8 @@
   },
   "dependencies": {
     "@modelcontextprotocol/sdk": "^1.21.1",
-    "dotenv": "^16.6.1"
+    "dotenv": "^16.6.1",
+    "undici": "^6.20.0"
   },
   "devDependencies": {
     "@types/node": "^20",