feat: 添加 OpenAI API 代理支持

- 新增 /openai/v1/* 路由代理 OpenAI API
- 添加 OPENAI_BASE_URL 环境变量支持
- 更新日志记录支持 provider 字段

使用方式:
- Claude API: /v1/*
- OpenAI API: /openai/v1/*

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

src/index.ts

@@ -1,6 +1,7 @@
 import 'dotenv/config';
 import express from 'express';
 import { proxyHandler } from './proxy.js';
+import { openaiProxyHandler } from './proxy-openai.js';
 import { healthHandler } from './health.js';
 
 const app = express();
@@ -12,14 +13,18 @@ app.use(express.json({ limit: '50mb' }));
 // 健康检查端点
 app.get('/health', healthHandler);
 
-// 代理所有 /v1/* 路由
+// Claude API 代理路由: /v1/*
 app.all('/v1/*', proxyHandler);
 
+// OpenAI API 代理路由: /openai/v1/*
+app.all('/openai/v1/*', openaiProxyHandler);
+
 // 启动服务器
 const server = app.listen(PORT, () => {
-  console.log(`Claude API Proxy 服务已启动`);
+  console.log(`API Proxy 服务已启动`);
   console.log(`端口: ${PORT}`);
-  console.log(`上游 API: ${process.env.ANTHROPIC_BASE_URL || 'https://api.anthropic.com'}`);
+  console.log(`Claude API: ${process.env.ANTHROPIC_BASE_URL || 'https://api.anthropic.com'}`);
+  console.log(`OpenAI API: ${process.env.OPENAI_BASE_URL || 'https://api.openai.com'}`);
   console.log(`健康检查: http://localhost:${PORT}/health`);
 });
 

src/logger.ts

@@ -10,6 +10,7 @@ export interface LogEntry {
   duration: number;
   stream?: boolean;
   error?: string;
+  provider?: string;
 }
 
 export function log(entry: LogEntry): void {
@@ -26,7 +27,7 @@ export function createLogEntry(
   path: string,
   status: number,
   duration: number,
-  options?: { stream?: boolean; error?: string }
+  options?: { stream?: boolean; error?: string; provider?: string }
 ): LogEntry {
   return {
     time: new Date().toISOString(),

src/proxy-openai.ts

@@ -0,0 +1,131 @@
+import { Request, Response } from 'express';
+import axios from 'axios';
+import { log, createLogEntry } from './logger.js';
+
+// OpenAI 需要透传的 headers
+const OPENAI_PROXY_HEADERS = [
+  'authorization',
+  'content-type',
+  'accept',
+  'openai-organization',
+  'openai-beta',
+];
+
+// 获取 OpenAI 上游 API 基础 URL
+function getOpenAIBaseUrl(): string {
+  return process.env.OPENAI_BASE_URL || 'https://api.openai.com';
+}
+
+// 提取需要透传的 headers
+function extractProxyHeaders(req: Request): Record<string, string> {
+  const headers: Record<string, string> = {};
+  for (const header of OPENAI_PROXY_HEADERS) {
+    const value = req.headers[header];
+    if (value) {
+      headers[header] = Array.isArray(value) ? value[0] : value;
+    }
+  }
+  return headers;
+}
+
+// OpenAI 代理处理函数
+export async function openaiProxyHandler(req: Request, res: Response): Promise<void> {
+  const startTime = Date.now();
+  const method = req.method;
+  // 移除 /openai 前缀，保留 /v1/... 路径
+  const requestPath = req.path.replace(/^\/openai/, '');
+  const baseUrl = getOpenAIBaseUrl();
+  const targetUrl = `${baseUrl}${requestPath}`;
+
+  // 判断是否为流式请求
+  const isStream = req.body?.stream === true;
+
+  // 提取透传 headers
+  const headers = extractProxyHeaders(req);
+
+  try {
+    const response = await axios({
+      method: method,
+      url: targetUrl,
+      data: req.body,
+      headers,
+      responseType: isStream ? 'stream' : 'json',
+    });
+
+    if (isStream) {
+      // 流式响应处理
+      res.setHeader('Content-Type', 'text/event-stream');
+      res.setHeader('Cache-Control', 'no-cache');
+      res.setHeader('Connection', 'keep-alive');
+
+      const stream = response.data;
+
+      // 监听客户端断开
+      req.on('close', () => {
+        stream.destroy();
+      });
+
+      // 监听上游流错误
+      stream.on('error', (err: Error) => {
+        console.error('OpenAI 上游流错误:', err.message);
+        const duration = Date.now() - startTime;
+        log(createLogEntry(method, requestPath, 500, duration, { stream: true, provider: 'openai', error: err.message }));
+        if (!res.writableEnded) {
+          res.end();
+        }
+      });
+
+      // 管道传输
+      stream.pipe(res);
+
+      // 流结束时记录日志
+      stream.on('end', () => {
+        const duration = Date.now() - startTime;
+        log(createLogEntry(method, requestPath, 200, duration, { stream: true, provider: 'openai' }));
+      });
+    } else {
+      // 非流式响应处理
+      const duration = Date.now() - startTime;
+      log(createLogEntry(method, requestPath, response.status, duration, { stream: false, provider: 'openai' }));
+      res.status(response.status).json(response.data);
+    }
+  } catch (error: unknown) {
+    const duration = Date.now() - startTime;
+
+    if (axios.isAxiosError(error)) {
+      const status = error.response?.status || 500;
+      const errorData = error.response?.data;
+
+      log(createLogEntry(method, requestPath, status, duration, {
+        stream: isStream,
+        provider: 'openai',
+        error: errorData?.error?.message || error.message,
+      }));
+
+      if (isStream && error.response?.data) {
+        res.status(status).json(errorData);
+      } else {
+        res.status(status).json(errorData || {
+          error: {
+            message: error.message,
+            type: 'proxy_error',
+          },
+        });
+      }
+    } else {
+      const errorMessage = error instanceof Error ? error.message : 'Unknown error';
+      log(createLogEntry(method, requestPath, 500, duration, {
+        stream: isStream,
+        provider: 'openai',
+        error: errorMessage,
+      }));
+
+      res.status(500).json({
+        error: {
+          message: errorMessage,
+          type: 'internal_error',
+        },
+      });
+    }
+  }
+}