github.com/MetalBlockchain/metalgo@v1.11.9/vms/platformvm/txs/executor/subnet_tx_verification.go (about)

     1  // Copyright (C) 2019-2024, Ava Labs, Inc. All rights reserved.
     2  // See the file LICENSE for licensing terms.
     3  
     4  package executor
     5  
     6  import (
     7  	"errors"
     8  	"fmt"
     9  
    10  	"github.com/MetalBlockchain/metalgo/database"
    11  	"github.com/MetalBlockchain/metalgo/ids"
    12  	"github.com/MetalBlockchain/metalgo/vms/components/verify"
    13  	"github.com/MetalBlockchain/metalgo/vms/platformvm/state"
    14  	"github.com/MetalBlockchain/metalgo/vms/platformvm/txs"
    15  )
    16  
    17  var (
    18  	errWrongNumberOfCredentials       = errors.New("should have the same number of credentials as inputs")
    19  	errIsImmutable                    = errors.New("is immutable")
    20  	errUnauthorizedSubnetModification = errors.New("unauthorized subnet modification")
    21  )
    22  
    23  // verifyPoASubnetAuthorization carries out the validation for modifying a PoA
    24  // subnet. This is an extension of [verifySubnetAuthorization] that additionally
    25  // verifies that the subnet being modified is currently a PoA subnet.
    26  func verifyPoASubnetAuthorization(
    27  	backend *Backend,
    28  	chainState state.Chain,
    29  	sTx *txs.Tx,
    30  	subnetID ids.ID,
    31  	subnetAuth verify.Verifiable,
    32  ) ([]verify.Verifiable, error) {
    33  	creds, err := verifySubnetAuthorization(backend, chainState, sTx, subnetID, subnetAuth)
    34  	if err != nil {
    35  		return nil, err
    36  	}
    37  
    38  	_, err = chainState.GetSubnetTransformation(subnetID)
    39  	if err == nil {
    40  		return nil, fmt.Errorf("%q %w", subnetID, errIsImmutable)
    41  	}
    42  	if err != database.ErrNotFound {
    43  		return nil, err
    44  	}
    45  
    46  	return creds, nil
    47  }
    48  
    49  // verifySubnetAuthorization carries out the validation for modifying a subnet.
    50  // The last credential in [sTx.Creds] is used as the subnet authorization.
    51  // Returns the remaining tx credentials that should be used to authorize the
    52  // other operations in the tx.
    53  func verifySubnetAuthorization(
    54  	backend *Backend,
    55  	chainState state.Chain,
    56  	sTx *txs.Tx,
    57  	subnetID ids.ID,
    58  	subnetAuth verify.Verifiable,
    59  ) ([]verify.Verifiable, error) {
    60  	if len(sTx.Creds) == 0 {
    61  		// Ensure there is at least one credential for the subnet authorization
    62  		return nil, errWrongNumberOfCredentials
    63  	}
    64  
    65  	baseTxCredsLen := len(sTx.Creds) - 1
    66  	subnetCred := sTx.Creds[baseTxCredsLen]
    67  
    68  	subnetOwner, err := chainState.GetSubnetOwner(subnetID)
    69  	if err != nil {
    70  		return nil, err
    71  	}
    72  
    73  	if err := backend.Fx.VerifyPermission(sTx.Unsigned, subnetAuth, subnetCred, subnetOwner); err != nil {
    74  		return nil, fmt.Errorf("%w: %w", errUnauthorizedSubnetModification, err)
    75  	}
    76  
    77  	return sTx.Creds[:baseTxCredsLen], nil
    78  }