Execute Contract

In a cross-chain bridge, the executor contract (Executor) plays a crucial role. The executor contract for token cross-chain mainly provides two core methods for users to call:

1. bridge_proposal: Cross-Chain Proposal

2. bridge_finish: Cross-Chain Completion (Optional)

1. Cross-Chain Proposal Contract Interface

1.1. On the Endless chain, the interface for sending a cross-chain proposal is defined as follows:

public entry fun bridge_proposal(
        sender: &signer,
        source_token: address,
        to_chain: vector<u8>,
        to_contract: vector<u8>,
        to_who: vector<u8>,
        all_amount: u128,
        upload_gas_fee: u128
    )
​
public entry fun bridge_proposal_with_extra_data(
        sender: &signer,
        source_token: address,
        to_chain: vector<u8>,
        to_contract: vector<u8>,
        to_who: vector<u8>,
        all_amount: u128,
        upload_gas_fee: u128,
        extra_data: vector<u8>
    )

1.1.1. Parameter Description

1. sender: &signer - A reference to the signer of the message. Used to verify the sender’s identity and permissions, and to pay the gas fee.

2. source_token: address - The address of the token to be bridged across chains.

3. to_chain: vector<u8> - The identifier of the target chain, represented as a byte vector.

4. to_contract: vector<u8> - The target contract address on the destination chain, represented as a byte vector.

5. to_who: vector<u8> - The recipient address on the destination chain, represented as a byte vector.

6. all_amount: u128 - The total amount of tokens to be bridged, represented as an unsigned 128-bit integer.

7. upload_gas_fee: u128 - The gas fee required to send the message, represented as an unsigned 128-bit integer.

8. extra_data: vector<u8> - Additional data beyond the basic 128-bit structure, used for extensibility and advanced features. Represented as a byte vector.

1.2. The cross-chain proposal method and ABI on Sepolia, BSC, and Nile networks are as follows:

function bridgeToken(
        bytes32 source_token,
        Types.Chain memory to_chain,
        bytes32 to_who,
        bytes32 receiver,
        uint128 all_amount,
        uint128 upload_gas_fee
    ) public payable
​
function bridgeToken(
        bytes32 source_token,
        Types.Chain memory to_chain,
        bytes32 to_who,
        bytes32 receiver,
        uint128 all_amount,
        uint128 upload_gas_fee,
        bytes memory extra_data
    ) public payable

{
    "type": "function",
    "name": "bridgeToken",
    "inputs": [
      {
        "name": "source_token",
        "type": "bytes32",
        "internalType": "bytes32"
      },
      {
        "name": "to_chain",
        "type": "tuple",
        "internalType": "struct Types.Chain",
        "components": [
          {
            "name": "chain_type",
            "type": "uint8",
            "internalType": "uint8"
          },
          {
            "name": "chain_id",
            "type": "uint64",
            "internalType": "uint64"
          }
        ]
      },
      {
        "name": "to_who",
        "type": "bytes32",
        "internalType": "bytes32"
      },
      {
        "name": "receiver",
        "type": "bytes32",
        "internalType": "bytes32"
      },
      {
        "name": "all_amount",
        "type": "uint128",
        "internalType": "uint128"
      },
      {
        "name": "upload_gas_fee",
        "type": "uint128",
        "internalType": "uint128"
      }
    ],
    "outputs": [],
    "stateMutability": "payable"
  }

1.2.1. Parameter Description

1. source_token：The token to be bridged across chains.

2. to_chain：Information about the target chain.

3. to_who：The recipient address on the target chain.

4. receiver：The execution contract address on the target chain.

5. all_amount：The amount of tokens to bridge.

6. upload_gas_fee：

   • The gas fee required on the target chain (can be estimated before the cross-chain operation).

1.3. Cross-Chain Proposal Method Definition and IDL on Solana Chain

pub fn bridge_proposal(
    ctx: Context<Proposal>,
    to_chain: Chain,
    _to_token: [u8; 32],
    to_who: [u8; 32],
    all_amount: u64,
    upload_gas_fee: u64,
) -> Result<()>

{
      "name": "bridge_proposal",
      "discriminator": [
        158,
        136,
        135,
        169,
        41,
        252,
        48,
        232
      ],
      "accounts": [
        {
          "name": "sender",
          "writable": true,
          "signer": true
        },
        {
          "name": "token_mint",
          "writable": true
        },
        {
          "name": "sender_token",
          "writable": true
        },
        {
          "name": "fund_pool",
          "writable": true
        },
        {
          "name": "pool_account",
          "writable": true
        },
        {
          "name": "bridge_authority",
          "writable": true
        },
        {
          "name": "token_relation"
        },
        {
          "name": "chain_relation"
        },
        {
          "name": "to_chain_nonce_account",
          "writable": true
        },
        {
          "name": "message_fee",
          "writable": true
        },
        {
          "name": "bridge_config"
        },
        {
          "name": "bridge_core_program"
        },
        {
          "name": "program_id"
        },
        {
          "name": "token_program"
        },
        {
          "name": "associated_token_program"
        },
        {
          "name": "system_program"
        }
      ],
      "args": [
        {
          "name": "to_chain",
          "type": {
            "defined": {
              "name": "Chain"
            }
          }
        },
        {
          "name": "to_token",
          "type": {
            "array": [
              "u8",
              32
            ]
          }
        },
        {
          "name": "to_who",
          "type": {
            "array": [
              "u8",
              32
            ]
          }
        },
        {
          "name": "all_amount",
          "type": "u64"
        },
        {
          "name": "upload_gas_fee",
          "type": "u64"
        }
      ]
    }

1.3.1. Parameter Description

1. ctx: Context<Proposal> The context object containing all information related to the current transaction, including account states and permissions. This parameter ensures that the function executes within the correct context.

2. to_chain: Chain An enum type representing the destination chain. Specifies which blockchain network the proposal is being sent to (e.g., Ethereum, Binance Smart Chain, etc.).

3. _to_token: [u8; 32] A 32-byte array representing the target token. This parameter defines the token type to be bridged on the destination chain.

4. to_who: [u8; 32] A 32-byte array representing the recipient address on the target chain. This specifies the address that will receive the bridged assets.

5. all_amount: u64 An unsigned 64-bit integer representing the total amount of tokens to bridge. Indicates the number of assets the user intends to transfer.

6. upload_gas_fee: u64 An unsigned 64-bit integer representing the upload fee. This is the amount the sender must pay to submit the proposal, ensuring they have sufficient balance to proceed.

2. Cross-Chain Completion Contract Interface

2.1. The cross-chain completion interface is defined as follows on the Endless chain:

public entry fun bridge_finish(
        sender: &signer,
        msg_header: vector<u8>,
        msg_body: vector<u8>,
        multisig: vector<u8>,
        pks: vector<u64>
    )

2.1.1. Parameter Description

1. sender：The on-chain sender, representing the originator of the message.

2. msg_header：The message header, containing the header information of the message.

3. msg_body：The message body, containing the main content of the message.

4. multisig：The result of the BLS aggregated signature.

5. pks：The indexes of public keys used to generate the aggregated signature.

2.2. The message consumption method and ABI on Sepolia, BSC, and Nile chains are defined as follows:

function processMsg(
        Types.Message memory message,
        bytes[] memory signature // 65bytes for one signature
    ) public returns (bool)

{
    "type": "function",
    "name": "processMsg",
    "inputs": [
      {
        "name": "message",
        "type": "tuple",
        "internalType": "struct Types.Message",
        "components": [
          {
            "name": "msg_header",
            "type": "tuple",
            "internalType": "struct Types.MessageHeader",
            "components": [
              {
                "name": "msg_type",
                "type": "uint8",
                "internalType": "uint8"
              },
              {
                "name": "nonce",
                "type": "uint64",
                "internalType": "uint64"
              },
              {
                "name": "from_chain",
                "type": "tuple",
                "internalType": "struct Types.Chain",
                "components": [
                  {
                    "name": "chain_type",
                    "type": "uint8",
                    "internalType": "uint8"
                  },
                  {
                    "name": "chain_id",
                    "type": "uint64",
                    "internalType": "uint64"
                  }
                ]
              },
              {
                "name": "sender",
                "type": "bytes32",
                "internalType": "bytes32"
              },
              {
                "name": "to_chain",
                "type": "tuple",
                "internalType": "struct Types.Chain",
                "components": [
                  {
                    "name": "chain_type",
                    "type": "uint8",
                    "internalType": "uint8"
                  },
                  {
                    "name": "chain_id",
                    "type": "uint64",
                    "internalType": "uint64"
                  }
                ]
              },
              {
                "name": "receiver",
                "type": "bytes32",
                "internalType": "bytes32"
              },
              {
                "name": "upload_gas_fee",
                "type": "uint128",
                "internalType": "uint128"
              }
            ]
          },
          {
            "name": "msg_body",
            "type": "bytes",
            "internalType": "bytes"
          }
        ]
      },
      {
        "name": "signature",
        "type": "bytes[]",
        "internalType": "bytes[]"
      }
    ],
    "outputs": [
      {
        "name": "",
        "type": "bool",
        "internalType": "bool"
      }
    ],
    "stateMutability": "nonpayable"
  }

2.2.1. Parameter Description

1. message：(Type: Types.Message) Structure

   • msg_header：Message header, of type Types.MessageHeader

   • msg_type：Message type (uint8)

   • nonce：Message sequence number (uint64)

   • from_chain：Source chain information (Types.Chain)

     1. chain_type：Chain type (uint8)

     2. chain_id：Chain ID (uint64)

   • sender：Sender address (bytes32)

   • to_chain：Destination chain information (Types.Chain)

     1. chain_type：Chain type (uint8)

     2. chain_id：Chain ID (uint64)

   • receiver：Receiver address (bytes32)

   • upload_gas_fee：Upload gas fee (uint128)

   • msg_body：Message body (bytes)

2. signature：Array of message signatures (bytes[])

2.3. The cross-chain completion method definition and IDL on the Solana chain are as follows:

pub fn bridge_finish(
    ctx: Context<Consumption>,
    msg_header: MsgHeader,
    msg_body: MsgBody,
    accum_pk: Vec<u8>,
    signatures: Vec<[u8; 65]>,
) -> Result<()>

{
      "name": "bridge_finish",
      "discriminator": [
        99,
        177,
        36,
        34,
        56,
        39,
        63,
        99
      ],
      "accounts": [
        {
          "name": "sender",
          "writable": true,
          "signer": true
        },
        {
          "name": "token_mint",
          "writable": true
        },
        {
          "name": "receiver",
          "writable": true
        },
        {
          "name": "receiver_token_account",
          "writable": true
        },
        {
          "name": "bridge_authority"
        },
        {
          "name": "fund_pool",
          "writable": true
        },
        {
          "name": "pool_account",
          "writable": true
        },
        {
          "name": "token_relation"
        },
        {
          "name": "chain_relation"
        },
        {
          "name": "fee_token_relation"
        },
        {
          "name": "fee_token_mint",
          "writable": true
        },
        {
          "name": "fee_fund_pool",
          "writable": true
        },
        {
          "name": "fee_pool_account",
          "writable": true
        },
        {
          "name": "sender_fee_token_account",
          "writable": true
        },
        {
          "name": "from_chain_nonce_account",
          "writable": true
        },
        {
          "name": "message_fee",
          "writable": true
        },
        {
          "name": "bridge_config"
        },
        {
          "name": "bridge_core_program"
        },
        {
          "name": "program_id"
        },
        {
          "name": "token_program"
        },
        {
          "name": "associated_token_program"
        },
        {
          "name": "system_program"
        }
      ],
      "args": [
        {
          "name": "msg_header",
          "type": {
            "defined": {
              "name": "MsgHeader"
            }
          }
        },
        {
          "name": "msg_body",
          "type": {
            "defined": {
              "name": "MsgBody"
            }
          }
        },
        {
          "name": "accum_pk",
          "type": "bytes"
        },
        {
          "name": "signatures",
          "type": {
            "vec": {
              "array": [
                "u8",
                65
              ]
            }
          }
        }
      ]
    }

2.3.1. Parameter Description

1. ctx: Context<Consumption> The context object containing all information related to the current transaction, including account states and permissions. This parameter ensures the function executes within the correct context.

2. msg_header: MsgHeader The message header struct containing metadata about the message, such as sender address, timestamp, message type, etc. This provides the basic information of the message.

3. msg_body: MsgBody The message body struct containing the actual data to be confirmed. This can be any type of data, e.g., transaction details or instructions.

4. _accum_pk: Vec<u8> A byte vector representing the aggregated public keys, usually used to verify the message signature. This parameter may contain multiple public keys to ensure message authenticity.

5. signatures: Vec<[u8; 65]> A vector of signature byte arrays, each 65 bytes long. This stores signatures for the message, used to verify the message’s origin and integrity.