feat: 接入微信支付

packages/server/src/payment/wechat-pay.service.ts

@@ -34,7 +34,7 @@ export class WechatPayService {
   private readonly mchId: string
   private readonly mchKey: string
   private readonly mchSerialNo: string
-  private readonly mchPrivateKeyPath: string
+  private readonly mchPrivateKey: string
   private readonly notifyUrl: string
 
   constructor(private readonly config: ConfigService) {
@@ -42,13 +42,24 @@ export class WechatPayService {
     this.mchId = this.config.get<string>('WX_MCH_ID') ?? ''
     this.mchKey = this.config.get<string>('WX_MCH_KEY') ?? ''
     this.mchSerialNo = this.config.get<string>('WX_MCH_SERIAL_NO') ?? ''
-    this.mchPrivateKeyPath = this.config.get<string>('WX_MCH_KEY_PATH') ?? './certs/apiclient_key.pem'
+    this.mchPrivateKey = this.loadPrivateKey(
+      this.config.get<string>('WX_MCH_KEY_PATH') ?? './certs/apiclient_key.pem',
+    )
     this.notifyUrl = this.buildNotifyUrl()
   }
 
+  private loadPrivateKey(keyPath: string): string {
+    try {
+      return fs.readFileSync(path.resolve(keyPath), 'utf8')
+    } catch (err) {
+      this.logger.error(`Failed to read private key from ${keyPath}: ${err}`)
+      throw new Error('微信支付初始化失败: 无法读取商户私钥文件')
+    }
+  }
+
   private buildNotifyUrl(): string {
     const apiBase = this.config.get<string>('API_BASE_URL') ?? 'http://localhost:3000'
-    return `${apiBase}/payment/wx-notify`
+    return `${apiBase}/api/payment/wx-notify`
   }
 
   // ─── Public API ────────────────────────────────────────────────────────────
@@ -64,7 +75,7 @@ export class WechatPayService {
    *      amount { total (fen), currency }, payer { openid }
    *   2. Sign request with RSA-SHA256 using merchant private key
    *   3. Extract prepay_id from response
-   *   4. Build final paySign using HMAC-SHA256 over appId + timeStamp + nonceStr + packageStr
+   *   4. Build final paySign using RSA-SHA256 over appId + timeStamp + nonceStr + packageStr
    */
   async createUnifiedOrder(params: UnifiedOrderParams): Promise<WxPaymentParams> {
     this.logger.log(
@@ -119,13 +130,10 @@ export class WechatPayService {
     const prepayId = responseData.prepay_id
 
     // Step 3: Build payment params for mini-program
-    // The jsapi signature uses HMAC-SHA256 over: appId + timeStamp + nonceStr + packageStr
+    // V3 API uses RSA-SHA256 for mini-program payment signing
     const packageStr = `prepay_id=${prepayId}`
-    const signData = `${this.appId}\n${timeStamp}\n${nonceStr}\n${packageStr}\n`
-    const paySign = crypto
-      .createHmac('SHA256', this.mchKey)
-      .update(signData)
-      .digest('hex')
+    const paySignData = `${this.appId}\n${timeStamp}\n${nonceStr}\n${packageStr}\n`
+    const paySign = this.signWithRSA(paySignData)
 
     this.logger.log(`Payment params ready: orderNo=${params.orderNo}, prepayId=${prepayId}`)
 
@@ -133,7 +141,7 @@ export class WechatPayService {
       timeStamp,
       nonceStr,
       package: packageStr,
-      signType: 'HMAC-SHA256',
+      signType: 'RSA',
       paySign,
     }
   }
@@ -268,14 +276,8 @@ export class WechatPayService {
     // Sign with merchant's RSA private key using SHA256 with RSA
     const signature = this.signWithRSA(signString)
 
-    const authorization = [
-      `WECHATPAY2-SHA256-RSA2048`,
-      `mchid="${this.mchId}"`,
-      `nonce_str="${nonceStr}"`,
-      `signature="${signature}"`,
-      `timestamp="${timestamp}"`,
-      `serial_no="${this.mchSerialNo}"`,
-    ].join(', ')
+    const authorization =
+      `WECHATPAY2-SHA256-RSA2048 mchid="${this.mchId}",nonce_str="${nonceStr}",signature="${signature}",timestamp="${timestamp}",serial_no="${this.mchSerialNo}"`
 
     const response = await fetch(url, {
       method,
@@ -294,18 +296,10 @@ export class WechatPayService {
    * Sign data using RSA-SHA256 with the merchant's private key.
    */
   private signWithRSA(data: string): string {
-    let privateKey: string
-    try {
-      privateKey = fs.readFileSync(path.resolve(this.mchPrivateKeyPath), 'utf8')
-    } catch (err) {
-      this.logger.error(`Failed to read private key from ${this.mchPrivateKeyPath}: ${err}`)
-      throw new Error(`微信支付签名失败: 无法读取商户私钥文件`)
-    }
-
     const sign = crypto.createSign('RSA-SHA256')
     sign.update(data)
     sign.end()
-    return sign.sign(privateKey, 'base64')
+    return sign.sign(this.mchPrivateKey, 'base64')
   }
 
   /**
@@ -314,68 +308,44 @@ export class WechatPayService {
    * WeChat Pay v3 notification structure:
    *   {
    *     resource: {
-   *       ciphertext: "<base64 of AES-256-GCM encrypted JSON>",
-   *       nonce: "<16-byte nonce>",
-   *       associated_data: "<aead_key>"
+   *       ciphertext: "<base64 of AES-256-GCM encrypted JSON + auth tag>",
+   *       nonce: "<12-byte nonce>",
+   *       associated_data: "<aad>"
    *     }
    *   }
    *
-   * The encrypted `ciphertext` decodes to a JSON string:
-   *   { "ciphertext": "<base64 of notification JSON>",
-   *     "nonce": "<nonce>",
-   *     "associated_data": "<aad>" }
-   * where the nested `ciphertext` is again AES-256-GCM encrypted notification data.
-   *
-   * So decryption is two-step:
-   *   Step 1: AES-GCM(key, nonce, aad, outer_ciphertext) → outer_plaintext (JSON with nested ciphertext)
-   *   Step 2: AES-GCM(key, inner_nonce, inner_aad, inner_ciphertext) → final notification JSON
+   * The APIV3 key (mchKey, 32 bytes) is used as the AES-256-GCM key.
+   * The base64 decoded ciphertext has the 16-byte GCM auth tag appended at the end.
+   * Decryption yields the plain JSON notification data directly (single layer).
    */
   private decryptGCM(ciphertext: string, nonce: string, associatedData: string): string | null {
     try {
-      const keyBytes = Buffer.from(this.mchKey.slice(0, 32).padEnd(32, '0'), 'utf8')
+      // APIv3 key must be exactly 32 bytes
+      const keyBytes = Buffer.from(this.mchKey, 'utf8')
+      if (keyBytes.length !== 32) {
+        this.logger.error(`APIv3 key must be 32 bytes, got ${keyBytes.length}`)
+        return null
+      }
+
       const nonceBuffer = Buffer.from(nonce, 'utf8')
 
-      // ciphertext includes the 16-byte auth tag appended at the end (last 16 bytes)
-      const cipherBytes = Buffer.from(ciphertext.slice(0, -16), 'base64')
-      const authTag = Buffer.from(ciphertext.slice(-16), 'base64')
+      // Decode base64 ciphertext first, then split: last 16 bytes are auth tag
+      const cipherBuffer = Buffer.from(ciphertext, 'base64')
+      const authTag = cipherBuffer.subarray(cipherBuffer.length - 16)
+      const encryptedData = cipherBuffer.subarray(0, cipherBuffer.length - 16)
 
       const decipher = crypto.createDecipheriv('aes-256-gcm', keyBytes, nonceBuffer)
       decipher.setAuthTag(authTag)
+      if (associatedData) {
+        decipher.setAAD(Buffer.from(associatedData, 'utf8'))
+      }
 
-      const outerPlaintext = Buffer.concat([
-        decipher.update(cipherBytes),
+      const plaintext = Buffer.concat([
+        decipher.update(encryptedData),
         decipher.final(),
       ]).toString('utf8')
 
-      // Step 1 result: JSON string with nested ciphertext, nonce, associated_data
-      let outerJson: { ciphertext?: string; nonce?: string; associated_data?: string }
-      try {
-        outerJson = JSON.parse(outerPlaintext) as typeof outerJson
-      } catch {
-        this.logger.error(`Failed to parse outer notification JSON: ${outerPlaintext}`)
-        return null
-      }
-
-      const { ciphertext: innerCiphertext, nonce: innerNonce, associated_data: innerAad } = outerJson
-      if (!innerCiphertext || !innerNonce || !innerAad) {
-        this.logger.error('Missing fields in outer notification JSON')
-        return null
-      }
-
-      // Step 2: decrypt the nested ciphertext to get the final notification data
-      const innerCipherBytes = Buffer.from(innerCiphertext, 'base64')
-      const innerNonceBuffer = Buffer.from(innerNonce, 'utf8')
-
-      const decipher2 = crypto.createDecipheriv('aes-256-gcm', keyBytes, innerNonceBuffer)
-      // For step 2, the auth tag is the last 16 bytes of innerCipherBytes
-      decipher2.setAuthTag(Buffer.from(innerCiphertext.slice(-16), 'base64'))
-
-      const finalPlaintext = Buffer.concat([
-        decipher2.update(Buffer.from(innerCiphertext.slice(0, -16), 'base64')),
-        decipher2.final(),
-      ]).toString('utf8')
-
-      return finalPlaintext
+      return plaintext
     } catch (err) {
       this.logger.error(`Failed to decrypt notification: ${err}`)
       return null