How to access environmental information about a contract from within a chain extension?

Question

When we have an Ink! smart contract code calling a chain extension, how do we receive this information from within the chain extension:

1. The calling smart contract address/ID
2. The original caller of the smart contract (or is this possible?)
3. The equivalent EVM msg.value in the smart contract, if there is one?

If there is any tutorial/example that covers the above questions, it will be great just to paste the link out as well.

Thanks.

Answer 1

These environmental information is available to the ChainExtension through the Environment::ext() function. An instance of Environment is passed to ChainExtension::call() as a parameter.

The ext() function returns a type that implements Ext. Check out the linked documentation for the available functions.

To answer your question:

1. env.ext().caller()
2. We don't provide this functionality on purpose because basically every use of this information constitutes a security problem on Ethereum. We have env.ext().caller_is_origin(), though.
3. env.ext().value_transferred()