Remotely Signed S3 Requests

This is a library and tool designed to support doing Amazon S3 uploads and downloads with request signing occuring on a different machine than the machine performing the actual upload or download.

With this library, you can allow untrusted hosts to upload to an object which you've protected with whichever authentication and authorization scheme you choose.

There is support for both multipart and singlepart uploads and downloads. The high level interfaces provided will automatically select which version to use.

Architecture

This project is divided into a server-side component called the Controller. Instances of the Controller know how to generate and sign all the methods involved in uploading files to S3. Controllers also know how to run methods which must be run from the server. The methods which must be run from the server are the initate, complete and abort methods of the multipart uploads.

The Runner class is used by both the Client and Controller to run the underlying HTTP requests. Requests are passed between the Contoller and Client or between the Controller and Runner in something called interchange format. This format is a generalized HTTP request description which omits the body. The body must be provided to the HTTP request seperately

Here's an example of a simple request in this format:

{
  "url": "https://www.hostname.com:443/path/to/resource?query=string",
  "method": "GET",
  "headers": {
    "Content-Length": "1234",
  }
}

TODO: Write some stuff:

• Controller.prototype.generateGet: return a v4 signed request which allows access to an object
• Client support for downloading files
• command line tool to run all the requests
• command line tool to do a complete upload locally -- mainly as an integration test

Method Signatures:

In all cases, permissions and tags are optional parameters. The parameters of all functions are validated through the use of Joi schemas. These schemas are partially specified in the method body and comprised of schemas stored in src/schemas.js

Controller

• new Controller({region, runner, runnerOpts})
• Controller.prototype.initiateMultipartUpload({bucket, key, sha256, size, permissions}) -> uploadId
• Controller.prototype.generateMultipartRequest({bucket, key, uploadId, parts}) -> [{url, method, headers}]
• Controller.prototype.completeMultipartUplaod({bucket, key, etags, tags, uploadId}) -> 'ETAG_OF_OBJECT'
• Controller.prototype.abortMultipartUpload({bucket, key, uploadId}) -> void
• Controller.prototype.generateSinglepartRequest({bucket, key, sha256, size, tags, permissions}) -> {url, method, headers}

Runner

The public api of this method is the .run() method. All other methods which aren't prefixed with double underscores are OK to use externally but are not supported

• new Runner(agent, agentOpts)
• Runner.prototype.run({req, body, streamingOutput}) -> {body | bodyStream, headers, statusCode, statusMessage}

Client

The partsize parameter is the size of the multiple part of the upload in bytes. This value specifies how large each individual upload requets will be. The multisize parameter is the size of file which will cause the method to switch from single part upload to multipart upload.

• new Client({runner, runnerOpts, partsize, multisize}
• Client.prototype.prepareUpload({filename, forceSP, forceMP, partsize}) -> {filename, sha256, size, parts: [] | undefined
• Client.prototype.runUpload(request, upload) -> ['ETAG_OF_EACH_REQUEST']

Command line tools

TODO: write the command line tool that does upload and download

Examples

TODO: write some examples

Hacking

This library has a suite of unit tests which can be run without credentials.

npm install .
npm test

There are integration tests which can be run, but require S3 credentials and an existing bucket to test against.

export BUCKET=mybucket
export AWS_ACCESS_KEY_ID=myaccesskeyid
export AWS_SECRET_ACCESS_KEY=mytoken

npm test