Necko walkthrough

NECKO WALKTHROUGH(Data Protocol)

Tommy Kuo [:KuoE0] kuoe0@mozilla.com

2015.04.23 @Mozilla Taiwan

Outline• Create protocol channel

• Listener interface

• Open protocol channel

• Data transaction

Protocol

URI Syntax<scheme name> : <hierarchical part> [ ? <query> ] [ # <fragment> ]

http : //google.com/search ? q=Mozilla

https : //www.facebook.com/pages/郝神好神/871866229523862

file : ///Downloads/郝神好帥.jpg

about : config

mailto : kuoe0@mozilla.com

data : text/html;charset=utf-8;base64,6YOd56We5aW95bil

line : //shop/detail/xxx

Data Protocol

data:[<MIME-type>][;charset=<encoding>][;base64],<data>

A very simple protocol.

data:text/html;charset=utf-8;base64,6YOd56We5aW95bil

data:text/html;charset=utf-8;base64,6YOd56We5aW95bil

After base64 decoding…

Create Protocol Channel

handleCommand

openUILinkIn

openLinkIn

loadURIWithFlags (tabbrowser)

loadURIWithFlags (browser)

LoadURI(char16_t*, …)

LoadURIWithOptions

LoadURI(nsIURI*, …)

InternalLoad

DoURILoad

DoChannelLoad

NS_NewURI

NS_NewChannelInternal

Browser UI (XUL)

DocShell Necko

GetProtocolHandler

GetProtocolHandler

nsIURI

nsIChannel

NewURI

NewChannel2

GetProtocolHandler

1. Get protocol handler if it is cached.

2. Lookup in ‘about:config’ to check internal support.

3. For internal protocol, get internal protocol hander service and cache it.

4. For external protocol, get default external protocol handler service.

netwerk/base/nsIOService.cpp#406

data:text/html;charset=utf-8;base64,6YOd56We5aW95bil

GetProtocolHandler

nsDataHandler

nsSimpleURI nsDataChannel

NewURI() NewChannel2()

Protocol Handler API

Format the URI Create the channel Get flags

NewChannel2(…)

NewProxiedChannel2(…)

NewURI(…) GetProtocolFlags(…)

Protocol Handler

Internal External

lookup in /netwerk/protocol/ lookup in about:config

Internal protocol handler in /netwerk/protocol/

External protocol handler in about:config

Listener Interface

nsIStreamListener• onStartRequest()

• Called to signify the beginning of an asynchronous request.

• onStopRequest()

• Called to signify the end of an asynchronous request.

• onDataAvailable()

• This method is called when the next chunk of data for the ongoing request may be read without blocking the calling thread.

nsInputStreamPump… nsDataChannelnsHtml5StreamParser

OnStartRequest

OnStartRequest

OnStartRequest

OnDataAvailable

OnDataAvailable

OnDataAvailable

Read / ReadSegment

OnStopRequest

OnStopRequest

OnStopRequest

Open Protocol Channel

Initialize & Start

nsDataChannel

nsPipeInputStreamInitialize Stream & Pump

nsInputStreamPump

(event dispatcher)

(data source) notify on ready

create create

nsDocumentOpenInfo

nsDataChannel

nsInputStreamPump

Setup Listener Chain

listen

listen

notify

notify

Start Waiting nsInputStreamPump

nsDataChannel

nsPipeInputStream

AsyncRead()

AsyncWait()OnInputStreamReady()

Data Transaction

IDLE START

STOP TRANSFER

State of nsInputStreamPump

Must be in main thread!!

OnStateStart

OnStateStart

Create Content Viewer

nsDocShell

nsHTMLDocument

nsDocumentViewer

load

Set Content Listener

nsHtml5StreamParser

nsHtml5StreamListener

nsDocumentOpenInfo

listen

listen

notify

notify

nsDocumentOpenInfoCall OnStartRequest()

nsDataChannel

nsInputStreamPump

nsHtml5StreamParser

nsHtml5StreamListener

listen notify

listen notify

listen notify

listen notify

OnStateTransfer

OnStateTransfer

nsDocumentOpenInfoCall OnDataAvailable()

nsDataChannel

nsInputStreamPump

nsHtml5StreamParser

nsHtml5StreamListener

listen notify

listen notify

listen notify

listen notify

Read Data

nsPipeInputStream

Read/ReadSegment

nsHtml5StreamParser

nsPipeInputStream

data segment

nsHtml5StreamParser

parser buffer

temporal buffer

Call Read() in Main Thread

copy

dispatch to parser thread

nsPipeInputStream

data segment

nsHtml5StreamParser

parser buffer

Call ReadSegment() in Parser Thread

copy

OnStateStop

OnStateStop

nsDocumentOpenInfoCall OnStopRequest()

nsDataChannel

nsInputStreamPump

nsHtml5StreamParser

nsHtml5StreamListener

listen notify

listen notify

listen notify

listen notify

Thank you!