Simple P2P

Simple P2P is a minimalistic C/++ wrapper around the go implementation of libp2p. It wraps a gossip-sub rendevus based network and exposes a simple three function interface to connect to the network, and then send and recieve messages.

bool print(P2PMessage* message) {
    printf("Sender %s: %s", message->received_from, message->data);
    return true; // Did everything go well? False indicates we need to quit!
}

...

// All of the following values are set automatically by calling p2p_default_initialize_args(), then only any deviations from these values need to be specified
P2PInitializationArguments initInfo;
// A multiaddress storing both network and transport layer information (this is the address used by default)
initInfo.listenAddress = "/ip4/0.0.0.0/udp/0/quic-v1";
initInfo.listenAddressSize = strlen(initInfo.listenAddress);
// This is the name of the network... peers who are also discovering on this topic will be automatically found
initInfo.discoveryTopic = "simpleP2P";
initInfo.discoveryTopicSize = strlen(initInfo.discoveryTopic);
// Key used to define our identity, can be generated using p2p_generate_key(). If a null key is passed to init one will be generated automatically!
initInfo.identity = p2p_null_key();
// Time (in seconds) to wait before giving up and deciding that we can't find any peers;
initInfo.connectionTimeout = 60;
// Weather or not the library should print extra debugging information.
initInfo.verbose = false; 

// This function will block until a connection is established (or the timeout elapses) the networking will occur on a seperate thread which can be stopped by calling p2p_shutdown()
P2PNetwork network = p2p_initialize(initInfo);
// if (network < 0) an error has occured! (this function will block)

// Specifies that print should be called whenever we recieve a message from the network
p2p_set_message_callback(network, print);

...

// Sends a message to every connected peer (including ourself)
p2p_broadcast_message(network, "Hello World!", defaultTopic);
// or p2p_broadcast_messagen(data, size, topic); to avoid a call to strlen

Additional functions are provided to handle switching topics once we are connected to a network. Topics can be thought of as different channels/rooms in a chat application. Additional callbacks are provided for other events such as network connection and topic subscription. Check the documentation for a full list.

Note that simpleP2P only provides utilities to broadcast messages to an entire topic. If you want to ensure private communications with one specific peer, this will need to be handled seperately by your application using some form of encryption.

C++ Wrapper

A C++ wrapper is also provided! The above C example can be reproduced as follows:

void print(p2p::Network& network, p2p::Message& message) {
    std::cout << "Sender " << message.sender() << ": " << message.data_string() << std::endl;
}

...

// p2p::Network is a singleton... there can only be one of it and it can't be copied or moved!
// All of the arguments to the C initialization struct are presented and given default values
p2p::Network net(p2p::default_listen_address, "simpleP2P");
net.on_message.subscribe(print); // The += operator can be used as well

...

// NOTE: The network will automatically track the default topic
net.broadcast_message("Hello World!");

See the chat.cpp example and documentation for more details!

Building

SimpleP2P has no other C++ library dependencies, it is also setup to automaticlly fetch and build the go library dependencies using cmake. Thus all it needs is -> CMake >= 3.12 -> C/++ Compiler (supporting C++ 20 [specifically std::span] if the C++ wrapper is used) -> GO Compiler >= 1.19

SimpleP2P supports being added as subdirectory and will provide the simplep2p target your project can link against (includes both the C and C++ APIs).

You can also build the sample chat application by running

mkdir build
cd build
cmake .. -DBUILD_EXAMPLES=ON #-G Ninja
make # or ninja if your prefer
./chat --help # For a list of its commands

Note that in some cases the go module step will find versioning issues, CMake will identify this as failure and stop the build! If this happens simply rerun make and the build should finish as normal!

Windows: Linux: