Hippolyzer

Hippolyzer is a revival of Linden Lab's PyOGP library targeting modern Python 3, with a focus on debugging issues in Second Life-compatible servers and clients. There is a secondary focus on mocking up new features without requiring a modified server or client.

Wherever reasonable, readability and testability are prioritized over performance.

Almost all code from PyOGP has been either rewritten or replaced. Major changes from upstream include making sure messages always correctly round-trip, and the addition of a debugging proxy similar to ye olde WinGridProxy.

It supports hot-reloaded addon scripts that can rewrite, inject or drop messages. Also included are tools for working with SL-specific assets like the internal animation format, and the internal mesh format.

It's quick and easy to bash together a script that does something useful if you're familiar with low-level SL details. See the Local Animation addon example.

Setup

From Source

• Python 3.8 or above is required. If you're unable to upgrade your system Python package due to being on a stable distro, you can use pyenv to create a self-contained Python install with the appropriate version.
• Create a clean Python 3 virtualenv with python -mvenv
• Activate the virtualenv by running the appropriate activation script
• • Under Linux this would be something like source /bin/activate
• • Under Windows it's \Scripts\activate.bat
• Run pip install hippolyzer, or run pip install -e . in a cloned repo to install an editable version

Binary Windows Builds

Binary Windows builds are available on the Releases page. I don't extensively test these, building from source is recommended.

Proxy

A proxy is provided with both a CLI and Qt-based interface. The proxy application wraps a custom SOCKS 5 UDP proxy, as well as an HTTP proxy based on mitmproxy.

Multiple clients are supported at a time, and UDP messages may be injected in either direction. The proxy UI was inspired by the Message Log and Message Builder as present in the Alchemy viewer.

Proxy Setup

• Run the proxy with hippolyzer-gui
• • Addons can be loaded through the File -> Manage Addons menu or on the command-line like hippolyzer-gui addon_examples/bezoscape.py
• • If you want the command-line version, run hippolyzer-cli
• Install the proxy's HTTPS certificate by going to File -> Install HTTPS Certs
• • You can also install it with hippolyzer-cli --setup-ca . On Linux that would be ~/.firestorm_x64/ if you're using Firestorm.
• • Certificate validation can be disabled entirely through viewer debug setting NoVerifySSLCert, but is not recommended.

Windows

Windows viewers have broken SOCKS 5 proxy support. To work around that, you need to use a wrapper EXE that can make the viewer to correctly talk to Hippolyzer. Follow the instructions on https://github.com/SaladDais/WinHippoAutoProxy to start the viewer and run it through Hippolyzer.

The proxy should not be configured through the viewer's own preferences panel, it won't work correctly.

OS X & Linux

SOCKS 5 works correctly on these platforms, so you can just configure it through the preferences -> network -> proxy settings panel:

• Start the viewer and configure it to use 127.0.0.1:9061 as a SOCKS proxy and 127.0.0.1:9062 as an HTTP proxy. You must select the option in the viewer to use the HTTP proxy for all HTTP traffic, or logins will fail.
• Optionally, If you want to reduce HTTP proxy lag you can have asset requests bypass the HTTP proxy by setting the no_proxy env var appropriately. For ex. no_proxy="asset-cdn.glb.agni.lindenlab.com" ./firestorm.
• Log in!

Filtering

By default, the proxy's display filter is configured to ignore many high-frequency messages. The filter field allows filtering on the presence of specific blocks or the values of variables.

For example, to find either chat messages mentioning "foo" or any message referencing 125214 in an ID field you could use ChatFrom*.ChatData.Message~="foo" || *.*.*ID==125214. To find all ObjectUpdates related to object ID 125214 you could do *ObjectUpdate*.ObjectData.*ID==125214 || *ObjectUpdate*.ObjectData.Data.*ID==125214 to parse through both templated fields and fields inside the binary Data fields for compressed and terse object updates.

Messages also have metadata attached that can be matched on. To match on all kinds of ObjectUpdates that were related to the most recently selected object at the time the update was logged, you could do a filter like Meta.ObjectUpdateIDs ~= Meta.SelectedLocal

Similarly, if you have multiple active sessions and are only interested in messages related to a specific agent's session, you can do (Meta.AgentID == None || Meta.AgentID == "d929385f-41e3-4a34-a04e-f1fc39f24f12") && ....

Vectors can also be compared. This will get any ObjectUpdate variant that occurs within a certain range: (*ObjectUpdate*.ObjectData.*Data.Position > (110, 50, 100) && *ObjectUpdate*.ObjectData.*Data.Position < (115, 55, 105))

If you want to compare against an enum or a flag class in defined in templates.py, you can just specify its name: ViewerEffect.Effect.Type == ViewerEffectType.EFFECT_BEAM

Logging

Decoded messages are displayed in the log pane, clicking one will show the request and response for HTTP messages, and a human-friendly form for UDP messages. Some messages and fields have special packers defined that will give a more human-readable form of enum or binary fields, with the original form beside or below it.

For example, an AgentUpdate message may show up in the log pane like:

OUT AgentUpdate
# 15136: 
   
    

[AgentData]
  AgentID = [[AGENT_ID]]
  SessionID = [[SESSION_ID]]
  BodyRotation = (0.0, 0.0, 0.06852579861879349, 0.9976493446715918)
  HeadRotation = (-0.0, -0.0, 0.05799926817417145, 0.998316625570896)
  # Many flag fields are unpacked as tuples with the original value next to them
  State =| ('EDITING',) #16
  CameraCenter = <120.69703674316406, 99.8336181640625, 59.547847747802734>
  CameraAtAxis = <0.9625586271286011, 0.11959066987037659, -0.243267223238945>
  CameraLeftAxis = <-0.12329451739788055, 0.992370069026947, 0.0>
  CameraUpAxis = <0.24141110479831696, 0.029993515461683273, 0.9699592590332031>
  Far = 88.0
  ControlFlags =| ('YAW_POS', 'NUDGE_AT_POS') #524544
  Flags =| ('HIDE_TITLE',) #1

   

and an ObjectImage for setting a prim's texture may look like

OUT ObjectImage
# 3849: 
   
    

[AgentData]
  AgentID = [[AGENT_ID]]
  SessionID = [[SESSION_ID]]
[ObjectData]
  ObjectLocalID = 700966
  MediaURL = b''
  TextureEntry =| {'Textures': {None: '89556747-24cb-43ed-920b-47caed15465f'}, \
     'Color': {None: b'\xff\xff\xff\xff'}, \
     'ScalesS': {None: 1.0}, \
     'ScalesT': {None: 1.0}, \
     'OffsetsS': {None: 0}, \
     'OffsetsT': {None: 0}, \
     'Rotation': {None: 0}, \
     'BasicMaterials': {None: {'Bump': 0, 'FullBright': False, 'Shiny': 'MEDIUM'}}, \
     'MediaFlags': {None: {'WebPage': False, 'TexGen': 'DEFAULT', '_Unused': 0}}, \
     'Glow': {None: 0}, \
     'Materials': {None: '00000000-0000-0000-0000-000000000000'}}
  #TextureEntry = b'\x89UgG$\xcbC\xed\x92\x0bG\xca\xed\x15F_\x00\x00\x00\x00\x00\x00\x00\x00\x80?\x00\x00\x00\x80?\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'

   

All unpackers also provide equivalent packers that work with the message builder. The scripting interface uses the same packers as the logging interface, but uses a different representation. Clicking the "Copy repr()" will give you a version of the message that you can paste into an addon's script.

Building Messages

The proxy GUI includes a message builder similar to Alchemy's to allow building arbitrary messages, or resending messages from the message log window. Both UDP and Caps messages may be sent.

For example, here's a message that will drop a physical cube on your head:

OUT ObjectAdd

[AgentData]
  # [[]] in a field value indicates a simple replacement
  # provided by the proxy
  AgentID = [[AGENT_ID]]
  SessionID = [[SESSION_ID]]
  GroupID = [[NULL_KEY]]
[ObjectData]
  # =| means the we should use the field's special packer mode
  # We treat PCode as an enum, so we'll convert from its string name to its int val
  PCode =| 'PRIMITIVE'
  Material = 3
  # With =| you may represent flags as a tuple of strings rather than an int
  # The only allowed flags in ObjectAdd are USE_PHYSICS (1) and CREATE_SELECTED (2)
  AddFlags =| ('USE_PHYSICS',)
  PathCurve = 16
  ProfileCurve = 1
  PathBegin = 0
  PathEnd = 0
  PathScaleX = 100
  PathScaleY = 100
  PathShearX = 0
  PathShearY = 0
  PathTwist = 0
  PathTwistBegin = 0
  PathRadiusOffset = 0
  PathTaperX = 0
  PathTaperY = 0
  PathRevolutions = 0
  PathSkew = 0
  ProfileBegin = 0
  ProfileEnd = 0
  ProfileHollow = 0
  BypassRaycast = 1
  # =$ indicates an eval()ed field, this will result in a vector 3m above the agent.
  RayStart =$ AGENT_POS + Vector3(0, 0, 3)
  # We can reference whatever we put in `RayStart` by accessing `block`
  RayEnd =$ block["RayStart"]
  RayTargetID = [[NULL_KEY]]
  RayEndIsIntersection = 0
  Scale = <0.5, 0.5, 0.5>
  Rotation = <0.0, 0.0, 0.0, 1.0>
  State = 0

The repeat spinner at the bottom of the window lets you send a message multiple times. an i variable is put into the eval context and can be used to vary messages across repeats. With repeat set to two:

OUT ChatFromViewer

[AgentData]
  AgentID = [[AGENT_ID]]
  SessionID = [[SESSION_ID]]
[ChatData]
  # Simple templated f-string
  Message =$ f'foo {i * 2}'
  Type =| 'NORMAL'
  Channel = 0

will print

User: foo 0
User: foo 2
User: foo 4

HTTP requests may be sent through the same window, with equivalent syntax for replacements and eval() within the request body, if requested. As an example, sending a chat message through the UntrustedSimulatorMessage cap would look like:

POST [[UntrustedSimulatorMessage]] HTTP/1.1
Content-Type: application/llsd+xml
Accept: application/llsd+xml
X-Hippo-Directives: 1


   

    

   

Addon commands

By default, channel 524 is a special channel used for commands handled by addons' handle_command hooks. For ex, an addon that supplies a foo with one string parameter can be called by typing /524 foo something in chat.

/524 help will give you a list of all commands offered by currently loaded addons.

Useful Extensions

These are quick and dirty, but should be viewer features. I'm not a viewer developer, so they're here. If you are a viewer developer, please put them in a viewer.

• Local Animation - Allows loading and playing animations in LL's internal format from disk, replaying when the animation changes on disk. Mostly useful for animators that want quick feedback
• Local Mesh - Allows specifying a target object to apply a mesh preview to. When a local mesh target is specified, hitting the "calculate upload cost" button in the mesh uploader will instead apply the mesh to the local mesh target. It works on attachments too. Useful for testing rigs before a final, real upload.

Potential Changes

• AISv3 wrapper?
• Higher level wrappers for common things? I don't really need these, so only if people want to write them.
• Move things out of templates.py, right now most binary serialization stuff lives there because it's more convenient for me to hot-reload.
• Ability to add menus?

License

LGPLv3. If you have a good reason why, I might dual license.

This package includes portions of the Second Life(TM) Viewer Artwork, Copyright (C) 2008 Linden Research, Inc. The viewer artwork is licensed under the Creative Commons Attribution-Share Alike 3.0 License.

Contributing

Ensure that any patches are clean with no unnecessary whitespace or formatting changes, and that you add new tests for any added functionality.

Philosophy

With a few notable exceptions, Hippolyzer focuses mainly on decomposition of data, and doesn't provide many high-level abstractions for interpreting or manipulating that data. It's careful to only do lossless transforms on data that are just prettier representations of the data sent over the wire. Hippolyzer's goal is to help people understand how Second Life actually works, automatically employing abstractions that hide how SL works is counter to that goal.

For Client Developers

This section is mostly useful if you're developing a new SL-compatible client from scratch. Clients based on LL's will work out of the box.

Adding proxy support to a new client

Hippolyzer's proxy application actually combines two proxies, a SOCKS 5 UDP proxy and an HTTP proxy.

To have your client's traffic proxied through Hippolyzer the general flow is:

• Open a TCP connection to Hippolyzer's SOCKS 5 proxy port
• • This should be done once per logical user session, as Hippolyzer assumes a 1:1 mapping of SOCKS TCP connections to SL sessions
• Send a UDP associate command without authentication
• The proxy will respond with a host / port pair that UDP messages may be sent through
• At this point you will no longer need to use the TCP connection, but it must be kept alive until you want to break the UDP association
• Whenever you send a UDP packet to a remote host, you'll need to instead send it to the host / port from the UDP associate response. A SOCKS 5 header must be prepended to the data indicating the ultimate destination of the packet
• Any received UDP packets will also have a SOCKS 5 header indicating the real source IP and address
• • When in doubt, check socks_proxy.py, packets.py and the SOCKS 5 RFC for more info on how to deal with SOCKS.
• • https://github.com/SaladDais/WinHippoAutoProxy/blob/master/winhippoautoproxy/socks5udphooker.cpp is a simple example that wraps around recvfrom() and sendto() and could be used as a starting point.
• All HTTP requests must be sent through the Hippolyzer's HTTP proxy port.
• • You may not need to do any extra plumbing to get this to work if your chosen HTTP client respects the HTTP_PROXY environment variable.
• All HTTPS connections will be encrypted with the proxy's TLS key. You'll need to either add it to whatever CA bundle your client uses or disable certificate validation when a proxy is used.
• • mitmproxy does its own certificate validation so disabling it in your client is OK.
• The proxy needs to use content sniffing to figure out which requests are login requests, so make sure your request would pass MITMProxyEventManager._is_login_request()

Do I have to do all that?

You might be able to automate some of it on Linux by using LinHippoAutoProxy. If you're on Windows or MacOS the above is your only option.

Should I use this library to make an SL client in Python?

No. If you just want to write a client in Python, you should instead look at using libremetaverse via pythonnet. I removed the client-related code inherited from PyOGP because libremetaverse's was simply better.

https://github.com/CasperTech/node-metaverse/ also looks like a good, modern wrapper if you prefer TypeScript.