[Twilio+Slack] Slack に SMS 送信コマンドを実装する: SQS+Lambda での非同期処理構成 [2/3]

mkdir slack-sms-sender
cd slack-sms-sender
npm init -y
npm install twilio

const twilio = require('twilio');

const client = twilio(
  process.env.TWILIO_ACCOUNT_SID,
  process.env.TWILIO_AUTH_TOKEN
);

const https = require('https');

exports.handler = async (event) => {
  for (const record of event.Records) {
    const body = JSON.parse(record.body);
    const { to, message, response_url } = body;

    try {
      await client.messages.create({
        body: message,
        from: process.env.TWILIO_PHONE_NUMBER,
        to: to
      });

      await postToSlack(response_url, `✅ SMS を ${to} に送信しました。`);
    } catch (err) {
      console.error('Twilio error:', err);
      await postToSlack(response_url, `❌ SMS の送信に失敗しました。\nエラー: ${err.message}`);
    }
  }
};

// Slack の response_url にメッセージを POST
function postToSlack(responseUrl, message) {
  return new Promise((resolve, reject) => {
    const data = JSON.stringify({ text: message });

    const url = new URL(responseUrl);
    const options = {
      hostname: url.hostname,
      path: url.pathname + url.search,
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'Content-Length': Buffer.byteLength(data)
      }
    };

    const req = https.request(options, (res) => {
      console.log(`Slack response status: ${res.statusCode}`);
      resolve();
    });

    req.on('error', (e) => {
      console.error(`Slack response error: ${e.message}`);
      reject(e);
    });

    req.write(data);
    req.end();
  });
}

zip -r function.zip .

{
  "Records": [
    {
      "body": "{\"to\":\"+819012345678\",\"message\":\"テストメッセージ\",\"response_url\":\"https://hooks.slack.com/commands/xxx\"}"
    }
  ]
}

mkdir slack-sms-request-handler
cd slack-sms-request-handler
npm init -y
npm install aws-sdk

const crypto = require('crypto');
const querystring = require('querystring');
const { SQS } = require('aws-sdk');

const sqs = new SQS();

exports.handler = async (event) => {
    const headers = Object.fromEntries(
        Object.entries(event.headers || {}).map(([k, v]) => [k.toLowerCase(), v])
    );

    const timestamp = headers['x-slack-request-timestamp'];
    const slackSignature = headers['x-slack-signature'];

    if (!timestamp || !slackSignature) {
        return { statusCode: 400, body: '❌ 必要なヘッダーがありません。' };
    }

    // リプレイ攻撃対策
    const now = Math.floor(Date.now() / 1000);
    if (Math.abs(now - timestamp) > 60 * 5) {
        return { statusCode: 200, body: '❌ リクエストが古すぎます。' };
    }

    const rawBody = event.isBase64Encoded
        ? Buffer.from(event.body, 'base64').toString('utf8')
        : event.body;

    const sigBaseString = `v0:${timestamp}:${rawBody}`;
    const mySignature = 'v0=' + crypto
        .createHmac('sha256', process.env.SLACK_SIGNING_SECRET)
        .update(sigBaseString, 'utf8')
        .digest('hex');

    // 署名検証
    if (
        !crypto.timingSafeEqual(
            Buffer.from(mySignature, 'utf8'),
            Buffer.from(slackSignature, 'utf8')
        )
    ) {
        return { statusCode: 200, body: '❌ 署名検証に失敗しました。' };
    }

    const parsedBody = querystring.parse(rawBody);
    const text = parsedBody.text || '';
    const responseUrl = parsedBody.response_url;
    const [to, ...messageParts] = text.trim().split(/\s+/);
    const message = messageParts.join(' ');

    if (!to || !message) {
        return {
            statusCode: 200,
            body: '❌ 入力形式が正しくありません。\n使用例: /sms +81XXXXXXXXXX メッセージ本文'
        };
    }

    const sqsMessage = {
        to,
        message,
        response_url: responseUrl
    };

    try {
        await sqs.sendMessage({
            QueueUrl: process.env.SQS_QUEUE_URL,
            MessageBody: JSON.stringify(sqsMessage)
        }).promise();

        return {
            statusCode: 200,
            body: ''
        };
    } catch (err) {
        console.error('SQS error:', err);
        return {
            statusCode: 500,
            body: '❌ SQS への送信に失敗しました。'
        };
    }
};

zip -r function.zip .

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": "sqs:SendMessage",
      "Resource": "arn:aws:sqs:****"
    }
  ]
}

{
  "headers": {
    "X-Slack-Request-Timestamp": "1234567890",
    "X-Slack-Signature": "v0=fake"
  },
  "body": "text=%2B819012345678+テストメッセージ"
}