Enhanced File Upload

Enhanced File UploadDmitry Krivaltsevich

AgendaWhat we will talk about:

• How to upload files to the server• Java security model. Escape from the sandbox• POST-requests. Chunked or fixed-length?• Multi threaded applet VS single threaded JS 

HTML4. Form submit 

HTML4. Form submitImplementation:

hidden iframe

form target

HTML4. Form submit

Pros:• Native• Easy to implement

Cons:• Multiple file selection: not supported• Directory traversal: not supported• Drag & Drop from FS: not supported

HTML5. JS (File API + AJAX)Google use it for Google docs

HTML5. JS (File API + AJAX)

HTML5. JS (File API + AJAX)

• <input type="file" multiple=""/>• File API

Pros:• Multiple file selection• One input field for all files• Pre-processing files on client side

Implementation:

Cons:• Firefox 3.6.*: several implementation issues• IE: not supported• Directory traversal: not supported

Flash uploaderFacebook

Flash uploaderImplementation:• Embedded flash-object

Pros:• Multiple file selection• Various browsers: flash-plugin required

Cons:• Directory traversal: not supported

Java applet

ABC app

Google docs

Java appletHTML template

Java appletHTML template

HTTP-Only cookies

Java security model

JVM Sandbox

Classloader

Local or remote code (usigned / signed)

Security policy

Valuable resources (files, etc)

Escape from the sandbox

Signing

• Create keystore• Create private key• Create signed/self-signed certificate• Sign applet

Escape from the sandbox

Create key and certificate

Sign JAR

Escape from the sandboxSigning in ant

Escape from the sandboxSigning in maven

Escape from the sandbox

HTTP-POST Request

1 Boundary

1

1

1

2 Fixed-Length

2

3 Field name

3

4 Filename and directory path

4

Transfer-Encoding: chunkedExample

Explanation

Drag & Drop

Applet – JavaScript interactions

Multi threaded applet VS single threaded JS

Thread #1

Thread #2

Thread #3

JVM

Thread #3Thread #1Thread #1Thread #3Thread #2

JSThread #1

JSqueue

Upload appletImplementation:• Java-applet

Pros:• Multiple file and directories selection• Directory traversal• Drag & drop directly from File System

Cons:• Java & Java plugin required• Mac OS X: works only in Safari

Do you have any questions?

Thanks!