Sponsored Atomic Bridge

[l-monninger]

Description

Sponsors bridge transfers somewhat safely:

• Uses the balance of the framework minter to control max exploit.
• Requires a minimum transfer amount--ensuring attempt to exploit is costly for a small gain.
• Deducts sponsorship from transfer amount. Thus, insofar as bridge operation is trusted, the exploit cannot exceed the amount. And, in the case where refunds require Movement Labs approval, an exploit can always be averted.

To test:

movement move test -f sponsor

To be safer, include the sponsorship fee from movementlabsxyz/movement#896. As long as the fee is greater than or equal to sponsored amount, this is safe.

Type of Change

• New feature
• Bug fix
• Breaking change
• Performance improvement
• Refactoring
• Dependency update
• Documentation update
• Tests

Which Components or Systems Does This Change Impact?

• Validator Node
• Full Node (API, Indexer, etc.)
• Move/Aptos Virtual Machine
• Aptos Framework
• Aptos CLI/SDK
• Developer Infrastructure
• Other (specify)

How Has This Been Tested?

Key Areas to Review

Checklist

• I have read and followed the CONTRIBUTING doc
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I identified and added all stakeholders and component owners affected by this change as reviewers
• I tested both happy and unhappy path of the functionality
• I have made corresponding changes to the documentation

[andygolay]

Suggested change

	/// Sponsors a recipient by transferring enought Aptos Coint to make the claim to them
	/// Sponsors a recipient by transferring enought Aptos Coin to make the claim to them

[andygolay]

LGTM; logic makes sense and tests pass locally.

[andygolay]

Suggested change

	fun test_lock_for_ineligible_sponsor(aptos_framework: &signer, third_party: &signer) acquires BridgeCounterpartyEvents {
	fun test_lock_for_ineligible_sponsorship(aptos_framework: &signer, third_party: &signer) acquires BridgeCounterpartyEvents {

This isn't a test of whether a specific sponsor is eligible, but whether a transfer is eligible for sponsorship.

[andygolay]

Suggested change

	/// Sponsors a recipient by transferring enough Aptos Coin to make the claim to them if they are eligible
	/// Sponsors a recipient by transferring enough Aptos Coin for them to claim if the transfer is eligible

[andygolay]

Suggested change

	fun test_lock_for_eligible_sponsor(aptos_framework: &signer, third_party: &signer) acquires BridgeCounterpartyEvents {
	fun test_lock_for_eligible_sponsorship(aptos_framework: &signer, third_party: &signer) acquires BridgeCounterpartyEvents {

This isn't a test of whether a specific sponsor is eligible, but whether a transfer is eligible for sponsorship.

[l-monninger]

Agreed