aws-sign.js

var
  crypto = require('crypto'),
  url = require('url'),
  querystring = require('querystring');


function AWSRestSigner(credentials) {
  this.accessKeyId = credentials.accessKeyId;
  this.secretAccessKey = credentials.secretAccessKey;
  this.debug = false;
}

AWSRestSigner.subResources = ['acl', 'lifecycle', 'location', 'logging', 'notification', 'partNumber', 'policy', 'requestPayment', 'torrent', 'uploadId', 'uploads', 'versionId', 'versioning', 'versions', 'website'];

AWSRestSigner.prototype.canonizeAwzHeaders = function(xAmzHeaders) {
  if (xAmzHeaders) {
    var lcHeaders = {};
    Object.keys(xAmzHeaders).forEach(function(header) {
      var h = header.toLowerCase();
      if (h!='x-amz-date')  {
        lcHeaders[h]=xAmzHeaders[header];
      }
    });

    return Object.keys(lcHeaders)
      .map(function(header) {
        return header.toLowerCase();
      })
      .sort()
      .map(function(header) {
        return header+':'+lcHeaders[header]+"\n";
      })
      .join('');
  } else {
    return '';
  }
}

AWSRestSigner.prototype.extractSubResources = function(queryString) {
  var query = querystring.parse(queryString);

  var subresources = [];
  Object.keys(query).forEach(function(param) {
    if (AWSRestSigner.subResources.indexOf(param)>=0) {
      subresources.push(param);
    }
  });

  if (subresources.length) {
    subresources = subresources.sort();
    var queryToSign = subresources.map(function(param) {
      var result = param;
      if (query[param]!='') {
        result+="="+query[param];
      }
      return result;
    });
    return "?"+queryToSign.join("&")
  }

  return '';
}

AWSRestSigner.prototype.sign = function(opts) {
  var urlData = url.parse(opts.url);
  var
    method = opts.method,
    host = urlData.hostname || '',
    path = urlData.pathname,
    xAmzHeaders = {},
    date, contentType, contentMd5,
    bucket = "";



  var _match = host.match(/^(.*)\.s3\.amazonaws\.com/);
  if (_match) {
    bucket = _match[1];
  } else {
    bucket = host;
  }

  if (!opts.headers) {
    opts.headers = {};
  }

  Object.keys(opts.headers).forEach(function(key) {
    var lcKey = key.toLowerCase();
    switch(lcKey) {
      case "date":
        date = opts.headers[key];
        break;
      case "content-type":
        contentType = opts.headers[key];
        break;
      case "content-md5":
        contentMd5 = opts.headers[key];
        break;
      default:
        if("x-amz-" === lcKey.slice(0, 6)) {
          xAmzHeaders[lcKey] = opts.headers[key];
        }
        break;
    }
  });

  if (!date) {
    date = new Date().toUTCString();
    opts.headers.date = date;
  }

  opts.headers["Authorization"] = this._sign(method, bucket, path, date, contentType, contentMd5, xAmzHeaders);

  return opts;
}


AWSRestSigner.prototype._sign = function(method, bucket, path, date, contentType, contentMd5, xAmzHeaders) {
  var qPos = path.indexOf('?'), queryToSign='';
  if (qPos>=0) {
    var queryPart = path.substr(qPos+1, path.length);
    path = path.substr(0,qPos);
    queryToSign = this.extractSubResources(queryPart);
  }

  var canonicalizedAmzHeaders = this.canonizeAwzHeaders(xAmzHeaders);

  var canonicalizedResource = '';
  if (bucket!='') {
    canonicalizedResource += '/'+bucket;
  }
  canonicalizedResource += path + queryToSign;

  var stringToSign = method + "\n";
  if (contentMd5) {
    stringToSign += contentMd5;
  }
  stringToSign += "\n";

  if (contentType) {
    stringToSign += contentType;
  }
  stringToSign += "\n";

  stringToSign +=
    date + "\n" +
    canonicalizedAmzHeaders +
    canonicalizedResource;

  if (this.debug) {
    console.log("-----------")
    console.log(stringToSign.replace(/\n/g, "\\n\n"));
    console.log("-----------")
  }

  return 'AWS ' + this.accessKeyId + ':' + crypto.createHmac('sha1', this.secretAccessKey).update(stringToSign).digest('base64');
}

module.exports = AWSRestSigner;