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Using The Dialog Usage Manager (DUM)Derek MacDonald

reSIProcate Core DeveloperSenior Software Engineer, Xten Networks

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Background

• reSIProcate project started out of VOCAL / Vovida.org in Summer 2002

• http://www.sipfoundry.org/resiprocate• Became part of SIPfoundry early in 2004• Informal project organization• Many core developers participate or lead SIP standards

effort in the IETF• Attended SIPit 12, 13 and 14, 15, 16• DUM component added Summer 2004• Vovida (BSD) License

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Agenda

• Part I– reSIPprocate Introduction

• Programming with reSIProcate

• Examples

• Part II– The DialogUsageManager (DUM)

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Typical Applications

• Phones (e.g. embedded)

• Softphones (any platform)

• Gateways

• Proxies

• B2BUAs

• IM / Presence Servers or Clients

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Current Features

• Multi-homed hosts

• Platforms: Windows, Linux, BSD, Solaris, QNX, OS/X

• MIME & S/MIME

• Extendable contents

• User Agent Library (DUM)

• UDP, TCP, TLS

• Object-oriented interface

• Lazy Parser

• RFC 3261 compliant

• Asynchronous DNS

• Single or multi-threaded

• DNS support (NAPTR/SRV)

• IPv6

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Supported RFCs

• Supported RFCs:– 2327: SDP– 2617: HTTP Digest– 2782: DNS SRV – 2915: DNS NAPTR– 2976: sip INFO– 3261: sip– 3263: Locating sip servers– 3265: subscribe/notify– 3420: sipfrag– 3325: network asserted id– 3428: sip MESSAGE– 3326: reason header– 3515: sip REFER– 3581: symmetric response

– 3323: Privacy mechanism– 3262: Reliable provisional– 3264: Offer/Answer– 3266: IPv6 in SDP– 3311: UPDATE– 3903: PUBLISH– 3857: Winfo

• In Development– draft-sip-session-timer– draft-sip-caller-prefs

• Drafts: (partial list)– draft-impp-srv, draft-simple-presence– draft-sip-replaces, draft-sip-referredby– Draft-sip-connect-reuse– draft-sip-join, sip-gruu– sipping-mwi

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Supported Platforms

• Windows

• Linux

• MAC

• QNX

• Others

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Licensing

• The Vovida Software License, Version 1.0

• BSD-like (one line difference)

• Free

• Can use it in commercial products

• Re-contribution not required (no forced reciprocity)

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Some Example Deployments

• PurpleComm (http://www.purplecomm.com)– Proxy, Registrar, Voicemail, Presence Server– Windows Softphone (http://teltel.com)

• Jasomi Networks (http://www.jasomi.com)– PeerPoint – Session Border Controller

• Xten Networks (http://www.xten.com)– eyeBeam(DUM)

• CSP – Italy (http://www.csp.it)– IM/Audio/Video UA for Windows– Conference Server and h.323 gateway in development

• Computer Talk Technology (http://www.computer-talk.com)– Contact Center product(DUM)

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Architecture

TimerQueue

UDPTransport

FIFO

TLSTransport

FIFO

TCPTransport

FIFO

TransportSelector

tx event

add

DNS

request

response

SipStack

FIFO

Transaction

FIFO

add

app event

even

ts

Application / DUM

MsgScanner

Parsers

Message

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“hello world”

• Use Helper class to help construct messages#include “resiprocate/SipStack.hxx”

#include “resiprocate/Helper.hxx”

#include “resiprocate/SipMessage.hxx”

#include “resiprocate/NameAddr.hxx”

using namespace resip;

…

SipStack stack;

stack.addTransport(TCP, 5060);

NameAddr from(“<sip:jason@teltel.com>”);

auto_ptr<SipMessage> reg(Helper::makeRegister(from, from);

stack.send(*reg);

…

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SIP Messages

• Let the stack manage its own thread and select callSipStack stack;

StackThread stackThread(stack);

stackThread.run();

While(usleep(10)) {

SipMessage* msg = stack.receive();

if (msg) {

// process the incoming sip message

delete msg;

}

}

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Threading Model

• Single Threaded Mode– One thread for the entire application

– Manage file descriptors at the app level

• Multi-Threaded Mode– Optional thread per transport

– Optional StackThread

– DUM + DUM client must be one thread or provide sync

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SIP Headers

• http://www.sipfoundry.org/reSIProcate/using.txtSipMessage msg;NameAddr to;to.uri().user() = “jason”;to.uri().host() = “teltel.com”;msg.header(h_To) = to;msg.header(h_To).displayName() = “Jason Fischl”;assert(msg.exists(h_To));msg.header(h_CSeq).sequence()++;

NameAddrs routes = msg.header(h_Routes);NameAddrs reversed = routes.reverse();for (NameAddrs::iterator i=routes.begin();

i != routes.end(); ++i){

std::cerr << *i << endl;}NameAddr firstRoute = routes.back();routes.pop_back();

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SIP Parameters

SipMessage request;assert(request.header(h_To).exists(p_tag)); // existsrequest.header(h_To).param(p_tag) = “jason”; // assignrequest.header(h_To).remove(p_tag); // removerequest.header(h_To).uri().param(p_q) = 1.0; // FloatParamrequest.header(h_Vias).front().param(p_branch).getTransactionId();

Auth auth;auth.scheme() = “Digest”;auth.param(p_nonce) = “blah”; // QuotedDataParamauth.param(p_algorithm) = “MD5”;

UnknownParameterType p_myparam(“myparam”);request.header(h_RequestLine).param(p_myparam) = “myvalue”;

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Contents

• Flexible, extensible Content management

• Multi-part MIME

SipMessage invite;

const SdpContents* offer =

dynamic_cast<const SdpContents*>(invite.getContents);

if (offer) {

SipMessage ok; // make from invite request

SdpContents answer; // make from the offer

ok.setContents(&answer);

delete offer;

}

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Practicalities

• Compilers– g++, VS.NET, VC++ 6

– Intel compiler

• Build environment– Windows

– Linux/Unix

– QNX

– MAC OS X

– Solaris

• Namespaces– All code in resip namespace

• Exceptions– BaseException

– Must catch

• Assertions– Can be compiled out

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Logging

#include “resiprocate/Logger.hxx”

#define RESIPROCATE_SUBSYSTEM resip::Subsystem::TEST

using namespace resip;

…

// can use Log::SYSLOG, Log::COUT or Log::FILE

Log::initialize(Log::COUT, Log::toLevel(“INFO”), argv[0]);

SipMessage msg;

InfoLog (<< “The message is “ << msg.brief());

DebugLog (<< “detail: “ << msg);

Log::setLevel(Log::Debug);

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Contact / Via

• By default, Contact and Via IP address, port and transport will be filled in by the TransportSelector

• Application can specify it and avoid stack population

• E.g.

SipMessage request;

…

request.header(h_Contacts).clear();

NameAddr contact; // default nothing filled in

request.header(h_Contacts).push_back(contact);

stack.send(request);

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DUM

• Introduction– DUM makes writing user agents easy– Hides the complex sip specific stuff

• Usages– Usage based rather than Dialog Based– ClientRegistration, InviteSession, ClientPublication,etc.

• Handlers– InviteSessionHandler, ClientRegistrationHandler, etc.

• What can you do with DUM?– Softphone– B2BUA– Load generator

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DUM Benefits

• Manage refreshes for you– Just set up registration binding and keep it active– Set up a subscription and keep it active. DUM will let you know when

new updates come in via NOTIFY requests– Keep an INVITE session active– Handles forking for you– Merged requests– GRUU(in progress)

• Implements Offer/Answer (rfc 3264)• Implements PRACK (rfc 3262)(in progress)• Manage Profile information such as authorization• Implements UAC and UAS

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Usages

• There is a DUM Usage and Handler class for every type of SIP Usage

• Dialog Usages are created when responses to a usage creating request are received

• Usages are given to the User(through a Handler call) by a Handle which has weak reference semantics

• DUM also has NonDialogUsages for persistent associations not in a dialog; PUBLISH and REGISTER

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A DUM Instance

• Created against an existing SipStack

• Create a MasterProfile(required), a UserProfile(fordigest), a ClientAuthManager(for digest)

• Different DUM & Stack threads used in this example

SipStack stack;

DialogUsageManager* dum = new DialogUsageManager(stack);

dum->addTransport(UDP, 12005);

dum->addTransport(TCP, 12005);

dum->addTransport(TLS, 12006); //client only

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A DUM Instance

SharedPtr<MasterProfile> uacMasterProfile(new MasterProfile);

auto_ptr<ClientAuthManager> uacAuth(new ClientAuthManager);

dum->setMasterProfile(uacMasterProfile);

dum->setClientAuthManager(uacAuth);

dum->getMasterProfile()-addSupportedMimeType(NOTIFY,

Mime(“application”, “pidf+xml”);SharedPtr<UserProfile> bob(new UserProfile(dum->getMasterProfile());…(set password & from for bob)

SampleSubHandler subHandler;

dum->addClientSubscriptionHandler(“presence”, &subHandler);

StackThread stackThread(stack); stackThread.run();

DumThread dumThread(dum); dumThread.run();

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Sample Handler

• SampleSubHander : public ClientSubscriptionHandler

• ClientSubscriptionHandle passed SampleSubHandler in each callback

• onNewSubscription/onTerminated called for each fork

virtual void onUpdateActive(ClientSubscriptionHandle h,

const SipMessage& notify){

myApp->updateDocument(notify);h->end(); //unsubscribe

}

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Usage Creation

User DUM ClientSubscription SampleSubHandler

makeSubscription

send

Notify arrives

new

onNewSubscription

onUpdateActive

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As a UAS

• DUM will call the appropriate onNewSession of an installed handler when a usage creating request is received

• Will send a 405/489 if no appropriate handler is installed

• ServerPagerMessage and ServerOutOfDialogRequestusages only exist until a response is set

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SIP Identity

A

Identity Service(repro)

B

request

Request w/ Identity

http get

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SIP Identity

• An Identity Service adds an Identity and Identity-Info header to requests, if the request passes a challenge

• Identity is a hash over particular headers(includingData& from) plus the body, signed by the private key of the service

• Identity-Info is target where the user can fetch the cert of the identity service

• An endpoint that receives the message uses this cert to validate the hash, and the hash to validate the message

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SIP Identity

• If DUM has an HttpProvider it will fetch from Identity-Info targets and validate the Identity of a Message– sample implementation based on CURL

• The SecurityAttributes class on a SipMessage details the Identity Strength and Encryption level of an incoming request

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Encrypted Traffic

• A DialogUsageManager::EncryptionLevel is an optional parameter to make* calls, such as makeInviteSession

• EncryptionLevel can be None(default), Sign, Encrypt, SignAndEncrypt

• makeInviteSession can take two Sdp bodies to use multipart-alternative

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S/MIME

• Mime type support– Multipart Signed

– Encrypted(pkcs7-mime)

– Multipart Alternative

• DUM will use the most encrypted body it can understand

• Key Management– Keys are looked up by AOR in the Security Object

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Profile

• Holds settings for an instance of DUM– default registration interval

– User agent header

• The UserProfile subclass has information which is specific to an AOR(shared secret and InstanceID)

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Invite Sessions

• Has two subclasses, ServerInviteSession and ClientInviteSession, but one handler

• ClientInviteSession and ServerInviteSession are only used explicitly until the Invite usage is fully established, then InviteSession is used

• Abstracts away the messages used to drive the offer/answer model

• Easy hold and transfer

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User Data

• As UAC– Optional AppDialogSet can be affiliated with any usage

• Passed into make* calls

– AppDialog created for each instance of a fork

• As UAS– AppDialogSetFactory can be installed into a DUM instance

• All usages have getAppDialogSet

• Dialog usages have getAppDialog

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Pager Mode IM

• ClientPagerMessage– not in a dialog, but has a client controlled lifespan

– Can queue messages

• ServerPagerMessage– Created for each incoming message, destroyed when a

response is sent

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Usages

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Contributors

• Companies:

• Organizations– Vovida.org

– SIPfoundry

• Contributors:– Adam Roach, adam@dynamicsoft.com– Alan Hawrylyshen, alan@jasomi.com– Bob Bramwell bob@jasomi.com– Bryan Ogawa bko@cisco.com– Cullen Jennings, fluffy@cisco.com– David Bryan, dave@bryan.cx– David Butcher, david@purplecomm.com– Derek MacDonald, derek@xten.com– Daniel Shi, daniel@xten.com– Jacob Butcher, resip@nowhen.com– Jason Fischl, jason@purplecomm.com– Ken Kittlitz <ken@jasomi.com>– Kevin Chmilar, kevin@jasomi.com– Robert Sparks, rjsparks@nostrum.com– Rohan Mahy, rmahy@cisco.com– Ryan Kereliuk, ryker@ryker.org– Scott Godin, slgodin@icescape.com

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How to Contribute

• Subscribe to SIPfoundry reSIProcate mailing list

• Get subversion access

• http://www.sipfoundry.org/resiprocate

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Contact

• Derek MacDonald– derek@xten.com, derek@sipfoundry.org

– http://www.sipfoundry.org