Solana C++ SDK

A header-only C++ SDK for on-chain programs (a.k.a. smart contracts) on the Solana blockchain.

Running the examples

Install the Solana Tool Suite version 1.7.0 or higher. To update your existing installation run solana-install init "v1.7.0". Be sure to switch to devnet for experimenting with the SDK: solana config set -ud.

Run make in this repository's root directory and follow the instructions to deploy the examples, e.g.:

$ solana program deploy dist/account_logger_example.so

Note the Program Id you're given when deploying a program; you'll need it for sending transactions. To that end, there are some simple Node.js scripts in the client directory. Change to the client directory and run npm install to download the dependencies. Client scripts take the Program Id as the first argument, as well as additional arguments, depending on the script. For example:

$ npm run account_logger_example HX9t2pYjL1HZ9da1xTpWCgwaJRUqSCvgHs2RaA4stwsq
$ npm run user_registry_example 867RPtW9GzwCg3xWs9PjJaSTT7cR7LqGq8g79jKEh49W myname

Highlights

These are some benefits of using the C++ SDK over writing plain C.

Type safety

• The SDK rarely requires users to operate with raw memory.
• It enforces const-correctness throughout.
• References are preferred over pointers.

Compile-time Base58 conversion

Public keys can be created from their Base58 encoding without any run-time overhead:

constexpr Pubkey clock_key = from_base58("SysvarC1ock11111111111111111111111111111111");

Sysvars via syscalls

A recent feature allowing programs to access Sysvar Cluster Data on-the-fly without the need to specify those accounts in the transaction:

sysvar::Clock clock;
sysvar::Rent rent;
if (account_info.lamports() < rent.minimum_balance(account_info.data_len())) {
    log("ERROR: Account", account_info.pubkey(), "is not rent-exempt at time", clock.unix_timestamp());
    sol_panic();
}

The SDK currently supports the Clock, EpochSchedule and Rent sysvars. They can also be read from the sysvar accounts by passing the AccountInfo to the constructor.

SystemInstruction constructors

Native Programs are commonly called via cross-program invocations. The SDK provides constructors for some of the instructions supported by the System Program:

Pubkey system_pubkey = native::SystemProgram::pubkey();
native::SystemProgram::CreateAccountParams params(Rent().minimum_balance(data_len), data_len, program_id);
Instruction create_account_instruction(system_pubkey, account_metas, params);

Easier handling of seeds

Program-derived addresses are obtained by calling the variadic find_pda or create_pda functions:

FoundPDA pda = find_pda(program_id, "user account prefix", SignerSeed(username));
log("pubkey:", pda.pubkey, "bump seed:", pda.bump_seed);

For a cross-program invocation, arrays of seeds are passed to the invoke_signed function as follows:

invoke_signed(create_account_instruction, account_infos, {
    {{"bank", SignerSeed(payer_pda.bump_seed)}},  // sign for payment
    {{"1234", SignerSeed(created_pda.bump_seed)}} // sign for the new account
});

Convenient logging

A variadic function with overloads for SDK types:

log("Logging account", account_info, "at time", sysvar::Clock());

Namespaces

With few exceptions such as the sol_panic macro, names are under the sol:: namespace and don't pollute the global namespace.

Disclaimer

This SDK is not officially supported by the Solana project. It should be considered alpha quality software at this point. Interfaces and implementation are subject to change.