server/eth: Implement ValidateContract.

server/asset/eth/common.go

@@ -59,6 +59,9 @@ const (
 	// which holds the ETH, an amount of ETH in gwei, and a random nonce to
 	// avoid duplicate coin IDs.
 	CIDAmount
+	// SecretHashSize is the byte-length of the hash of the secret key used
+	// in swaps.
+	SecretHashSize = 32
 )
 
 // CoinID is an interface that objects which represent different types of ETH

server/asset/eth/eth.go

@@ -18,7 +18,7 @@ import (
 
 	"decred.org/dcrdex/dex"
 	"decred.org/dcrdex/dex/encode"
-	swap "decred.org/dcrdex/dex/networks/eth"
+	dexeth "decred.org/dcrdex/dex/networks/eth"
 	"decred.org/dcrdex/server/asset"
 	"github.com/ethereum/go-ethereum"
 	"github.com/ethereum/go-ethereum/common"
@@ -74,7 +74,7 @@ func (d *Driver) DecodeCoinID(coinID []byte) (string, error) {
 
 // UnitInfo returns the dex.UnitInfo for the asset.
 func (d *Driver) UnitInfo() dex.UnitInfo {
-	return swap.UnitInfo
+	return dexeth.UnitInfo
 }
 
 // ethFetcher represents a blockchain information fetcher. In practice, it is
@@ -94,7 +94,7 @@ type ethFetcher interface {
 	syncProgress(ctx context.Context) (*ethereum.SyncProgress, error)
 	blockNumber(ctx context.Context) (uint64, error)
 	peers(ctx context.Context) ([]*p2p.PeerInfo, error)
-	swap(ctx context.Context, secretHash [32]byte) (*swap.ETHSwapSwap, error)
+	swap(ctx context.Context, secretHash [32]byte) (*dexeth.ETHSwapSwap, error)
 	transaction(ctx context.Context, hash common.Hash) (tx *types.Transaction, isMempool bool, err error)
 }
 
@@ -345,10 +345,12 @@ func (eth *Backend) ValidateCoinID(coinID []byte) (string, error) {
 	return coinId.String(), nil
 }
 
-// ValidateContract ensures that the swap contract is constructed properly, and
-// contains valid sender and receiver addresses.
-func (eth *Backend) ValidateContract(contract []byte) error {
-	return notImplementedErr
+// ValidateContract ensures that the secret hash is the correct length.
+func (eth *Backend) ValidateContract(secretHash []byte) error {
+	if len(secretHash) != SecretHashSize {
+		return fmt.Errorf("secret hash is wrong size: want %d but got %d", SecretHashSize, len(secretHash))
+	}
+	return nil
 }
 
 // CheckAddress checks that the given address is parseable.

server/asset/eth/eth_test.go

@@ -686,3 +686,31 @@ func TestTxData(t *testing.T) {
 		t.Fatalf("TxData error: %v", err)
 	}
 }
+
+func TestValidateContract(t *testing.T) {
+	tests := []struct {
+		name       string
+		secretHash []byte
+		wantErr    bool
+	}{{
+		name:       "ok",
+		secretHash: make([]byte, 32),
+	}, {
+		name:       "wrong size",
+		secretHash: make([]byte, 31),
+		wantErr:    true,
+	}}
+	for _, test := range tests {
+		eth := new(Backend)
+		err := eth.ValidateContract(test.secretHash)
+		if test.wantErr {
+			if err == nil {
+				t.Fatalf("expected error for test %q", test.name)
+			}
+			continue
+		}
+		if err != nil {
+			t.Fatalf("unexpected error for test %q: %v", test.name, err)
+		}
+	}
+}