Module libafl_bolts::llmp

A library for low level message passing

To send new messages, the clients place a new message at the end of their client_out_mem. If the current map is filled up, they place an end of page (EOP) msg and alloc a new ShMem. Once the broker mapped this same page, it flags it as safe for unmapping.

[client0]        [client1]    ...    [clientN]
  |                  |                 /
[client0_out] [client1_out] ... [clientN_out]
  |                 /                /
  |________________/                /
  |________________________________/
 \|/
[broker]

After the broker received a new message for clientN, (clientN_out->current_id != last_message->message_id) the broker will copy the message content to its own, centralized page.

The clients periodically check (current_broadcast_shmem->current_id != last_message->message_id) for new incoming messages. If the page is filled up, the broker instead creates a new page and places an end of page (EOP) message in its queue. The EOP buf contains the new description to access the shared map. The clients then switch over to read from that new current map.

[broker]
  |
[current_broadcast_shmem]
  |
  |___________________________________
  |_________________                  \
  |                 \                  \
  |                  |                  |
 \|/                \|/                \|/
[client0]        [client1]    ...    [clientN]

In the future, if we would need zero copy, the current_broadcast_shmem could instead list the client_out_shmem ID an offset for each message. In that case, the clients also need to create a new ShMem each time their bufs are filled up.

To use, you will have to create a broker using LlmpBroker::new(). Then, create some LlmpClients in other threads and register them with the main thread using LlmpBroker::register_client. Finally, call LlmpBroker::loop_forever().

For broker2broker communication, all messages are forwarded via network sockets.

Check out the llmp_test example in ./examples, or build it with cargo run --example llmp_test.

Structs

• BrokerId
  The broker ID, for broker 2 broker communication.
• Flags
  The flags, indicating, for example, enabled compression.
• LlmpBroker
  The broker (node 0)
• LlmpClient
  Client side of LLMP
• LlmpClientDescription
  A restorable client description
• LlmpDescription
  Description of a shared map. May be used to restore the map by id.
• LlmpMsg
  Message sent over the “wire”
• LlmpPage
  Contents of the share mem pages, used by llmp internally
• LlmpReceiver
  Receiving end on a (unidirectional) sharedmap channel
• LlmpSender
  Sending end on a (unidirectional) sharedmap channel
• LlmpSharedMap
  A page wrapper
• LlmpShutdownSignalHandler
  A signal handler for the LlmpBroker. On unix, it handles signals On Windows - control signals (e.g., CTRL+C)
• MessageId
  The message ID, an ever-increasing number, unique only to a sharedmap/page.
• Tag
  TAGs used throughout llmp
• TcpRemoteNewMessage
  Messages for broker 2 broker connection.

Enums

• Listener
  Abstraction for listeners
• ListenerStream
  A listener stream abstraction
• LlmpConnection
  An Llmp instance
• LlmpMsgHookResult
  Result of an LLMP Message hook
• TcpRequest
  This is for the server the broker will spawn. If an llmp connection is local - use sharedmaps or remote (broker2broker) - forwarded via tcp
• TcpResponse
  Responses for requests to the server.

Constants

• LLMP_FLAG_COMPRESSED
  This message was compressed in transit
• LLMP_FLAG_FROM_B2B
  From another broker.
• LLMP_FLAG_INITIALIZED
  Unused…

Functions

• recv_tcp_msg
  Receive one message of u32 len and [u8; len] bytes
• send_tcp_msg
  Send one message as u32 len and [u8;len] bytes