# 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.