Extend the `svm-codec` Wasm API with the `Envelope`

[YaronWittenstein]

Depends on #458

This issue will extend the Wasm API of the svm_codec.wasm Consequently, the svm-codec-npm will have to be extended as well

On the Simple Coin #Iteration 2, the svm_codec.wasm will be extended again to support the Signatures appended to the end of the Transaction.

@avive FYI

Extensions to be implemented:

1. Encode Envelope

   #[no_mangle]
   pub unsafe extern "C" fn wasm_encode_envelope(ptr: *mut u8) -> *mut u8 {
   ...
   }

The input should be a JSON:

{
  version: 0,
  type: 'deploy', // or `spawn` / `call`
  principal: '...',
  amount: 0,
  nonce: 0,
  gasLimit: 0,
  gasFee: 0
}

2. Decode Envelope

   #[no_mangle]
   pub unsafe extern "C" fn wasm_decode_envelope(ptr: *mut u8) -> *mut u8 {
   //
   }

Should return a JSON of the same schema as the input given to wasm_encode_envelope

3. Encode Transaction

#[no_mangle]
pub unsafe extern "C" fn wasm_encode_tx(env: *mut u8, msg: *mut u8) -> *mut u8 {
    ...
}

• The env will point to a Wasm buffer containing the encoded Envelope (as returned from wasm_encode_envelope).
• The msg will point to a Wasm buffer containing the encoded Message as returned from one of:
• wasm_encode_spawn
• wasm_encode_call
• For Deploy, the Message is the binary data given by the SVM SDK toolchain. That's why there's no wasm_encode_deploy.

@neysofu @avive, my recommendation is that the svm-codec-npm will introduce a method such as loadDeployTemplate that will ask for a file-path pointing to a binary Deploy Transaction.

Then, it will call wasm_alloc asking to allocate the Deploy Transaction size. Once the JS code holds the Wasm buffer, it will call again, this time to wasm_buffer_data and copy Deploy Transaction to the Wasm Instance Memory.

4. Decode Transaction

This one is a bit more tricky. Probably better to split into a couple of methods:

• Decode only the Envelope

First we'll have the wasm_extract_tx_envelope method:

#[no_mangle]
pub unsafe extern "C" fn wasm_extract_tx_envelope(ptr: *mut u8) -> *mut u8 {
    //
}

It will return a Wasm buffer pointing only to the Envelope part (in its binary form). Then a call to wasm_decode_envelope will return the Envelope in its JSON format.

• Decode only the Message

Similary, we'll have the wasm_extract_tx_message method:

#[no_mangle]
pub unsafe extern "C" fn wasm_extract_tx_message(ptr: *mut u8) -> *mut u8 {
    //
}

It will return a Wasm buffer pointing only to the Message part (in its binary form). Then a call to wasm_decode_spawn or wasm_decode_call will return the decoded Message in a JSON format.

Notes

• Don't forget to release Wasm Buffers by calling the wasm_free.
• The Deploy Template is out of scope for the decoding part.