Question

想使用NODEJS为IBM CLOUD OBJECT STORAGE生成一个预签名的url，这样最终用户只需单击url就可以下载对象，而我不必向所有用户提供COS访问权限。

我创建了一个存储桶，并使用{“ HMAC”：true}创建了服务凭证，因此生成了HMAC访问ID和秘密密钥。我使用了此处提供的代码（https://console.bluemix.net/docs/services/cloud-object-storage/hmac/presigned-urls.html#create-a-presigned-url）;网址已生成，但尝试访问该网址时，出现错误404，无法获取/ v2 / endpoints / bucket_name / file_name，该文件已经存在于相应的存储桶中。

这是使用的代码

const crypto = require('crypto');
const moment = require('moment');
const httpMethod = 'GET';
const host = 'control.cloud-object-storage.cloud.ibm.com/v2/endpoints';
const signature_endpoint = 'https://' + host
const expiration = 86400  // time in seconds
const signature_access_key = '**********************'; //                   cos_hmac_keys.access_key_id
const signature_secret_key = '************************'; //cos_hmac_keys..secret_access_key

function hashHex(msg) {
   var hash = crypto.createHash('sha256');
   hash.update(msg);
   return hash.digest('hex');
}

function hash(key, msg) {
   var hmac = crypto.createHmac('sha256', key);
   hmac.update(msg, 'utf8');
   return hmac.digest();
}

function createSignatureKey(key, datestamp, region, service) {
   keyDate = hash(('AWS4' + key), datestamp);
   keyString = hash(keyDate, region);
   keyService = hash(keyString, service);
   keySigning = hash(keyService, 'aws4_request');
   return keySigning;
}

function hmacHex(key, msg) {
   var hmac = crypto.createHmac('sha256', key);
   hmac.update(msg, 'utf8');
   return hmac.digest('hex');
}

function return_signature(filename) {
   var time = moment().utc();
   var timestamp = time.format('YYYYMMDDTHHmmss') + 'Z';
   var datestamp = time.format('YYYYMMDD');

   var standardizedQuerystring = 'X-Amz-Algorithm=AWS4-HMAC-SHA256' +
   '&X-Amz-Credential=' + encodeURIComponent(signature_access_key + 
   '/' + datestamp + '/' + region + '/s3/aws4_request') +
   '&X-Amz-Date=' + timestamp +
    &X-Amz-Expires=' + expiration.toString() +
   '&X-Amz-SignedHeaders=host';

   var standardizedResource = '/' + bucketName + '/' + filename;

   var payloadHash = 'UNSIGNED-PAYLOAD';
   var standardizedHeaders = 'host:' + host;
   var signedHeaders = 'host';

   var standardizedRequest = httpMethod + '\n' +
   standardizedResource + '\n' +
   standardizedQuerystring + '\n' +
   standardizedHeaders + '\n' +
   '\n' +
   signedHeaders + '\n' +
   payloadHash;

   // assemble string-to-sign
   var hashingAlgorithm = 'AWS4-HMAC-SHA256';
   var credentialScope = datestamp + '/' + region + '/' + 's3' + '/' + 
   'aws4_request';
   var sts = hashingAlgorithm + '\n' +
   timestamp + '\n' +
   credentialScope + '\n' +
   hashHex(standardizedRequest);

   signatureKey = createSignatureKey(signature_secret_key, datestamp,  
   region, 's3');
   signature = hmacHex(signatureKey, sts);

   var requestUrl = signature_endpoint + '/' +
   bucketName + '/' +
   filename + '?' +
   standardizedQuerystring +
   '&X-Amz-Signature=' +
   signature;

   console.log(`requestUrl: ${requestUrl}`);

   console.log(`\nSending ${httpMethod} request to IBM COS - --------- 
   -------------`);
   console.log('Request URL = ' + requestUrl);

   // create and send the request
   console.log(`\nSending ${httpMethod} request to IBM COS ----------- 
   ------------`);
   console.log('Request URL = ' + requestUrl);

   var request = https.get(requestUrl, function (response) {
   console.log('\nResponse from IBM COS ------------------------------ 
   ----');
   console.log(`Response code: ${response.statusCode}\n`);

   response.on('data', function (chunk) {
       console.log("response from request URL-------------------")
       console.log('Response: ' + chunk);
   });
 });

 request.end();

 return requestUrl;
}

访问预签名的URL从IBM COS下载对象时出现404错误

0 个答案: