Use placeholder nonce when serving L1 handlers over RPC (#1600)

Old L1 handlers don't have nonces, but the spec requires the nonce. We
use 0x0 as the placeholder.

A regression test is included.

clients/feeder/testdata/mainnet/transaction/0x5d50b7020f7cf8033fd7d913e489f47edf74fbf3c8ada85be512c7baa6a2eab.json

@@ -0,0 +1 @@
+{"execution_status": "SUCCEEDED", "finality_status": "ACCEPTED_ON_L1", "status": "ACCEPTED_ON_L1", "block_hash": "0x27d1e625a4293d2ed162eb2a1ad031cf71eaa2bab3a3d10fe9bddc51b877ccd", "block_number": 192, "transaction_index": 22, "transaction": {"transaction_hash": "0x5d50b7020f7cf8033fd7d913e489f47edf74fbf3c8ada85be512c7baa6a2eab", "version": "0x0", "contract_address": "0x58b43819bb12aba8ab3fb2e997523e507399a3f48a1e2aa20a5fb7734a0449f", "entry_point_selector": "0xe3f5e9e1456ffa52a3fbc7e8c296631d4cc2120c0be1e2829301c0d8fa026b", "calldata": ["0x5474c49483aa09993090979ade8101ebb4cdce4a", "0xabf8dd8438d1c21e83a8b5e9c1f9b58aaf3ed360", "0x2", "0x4c04fac82913f01a8f01f6e15ff7e834ff2d9a9a1d8e9adffc7bd45692f4f9a"], "type": "L1_HANDLER"}}

rpc/handlers.go

@@ -352,12 +352,15 @@ func AdaptTransaction(t core.Transaction) *Transaction {
 	case *core.DeployAccountTransaction:
 		txn = adaptDeployAccountTrandaction(v)
 	case *core.L1HandlerTransaction:
-		// https://github.com/starkware-libs/starknet-specs/blob/a789ccc3432c57777beceaa53a34a7ae2f25fda0/api/starknet_api_openrpc.json#L1669
+		nonce := v.Nonce
+		if nonce == nil {
+			nonce = &felt.Zero
+		}
 		txn = &Transaction{
 			Type:               TxnL1Handler,
 			Hash:               v.Hash(),
 			Version:            v.Version.AsFelt(),
-			Nonce:              v.Nonce,
+			Nonce:              nonce,
 			ContractAddress:    v.ContractAddress,
 			EntryPointSelector: v.EntryPointSelector,
 			CallData:           &v.CallData,

rpc/handlers_test.go

@@ -566,7 +566,7 @@ func TestTransactionByHash(t *testing.T) {
 			}`,
 		},
 
-		"L1 Handler v0": {
+		"L1 Handler v0 with nonce": {
 			hash:    "0x537eacfd3c49166eec905daff61ff7feef9c133a049ea2135cb94eec840a4a8",
 			network: utils.Mainnet,
 			expected: `{
@@ -585,6 +585,24 @@ func TestTransactionByHash(t *testing.T) {
        ]
    }`,
 		},
+		"L1 Handler v0 without nonce": {
+			hash:    "0x5d50b7020f7cf8033fd7d913e489f47edf74fbf3c8ada85be512c7baa6a2eab",
+			network: utils.Mainnet,
+			expected: `{
+				"type": "L1_HANDLER",
+				"transaction_hash":  "0x5d50b7020f7cf8033fd7d913e489f47edf74fbf3c8ada85be512c7baa6a2eab",
+				"version": "0x0",
+				"nonce": "0x0",
+				"contract_address":  "0x58b43819bb12aba8ab3fb2e997523e507399a3f48a1e2aa20a5fb7734a0449f",
+				"entry_point_selector": "0xe3f5e9e1456ffa52a3fbc7e8c296631d4cc2120c0be1e2829301c0d8fa026b",
+				"calldata": [
+					"0x5474c49483aa09993090979ade8101ebb4cdce4a",
+					"0xabf8dd8438d1c21e83a8b5e9c1f9b58aaf3ed360",
+					"0x2",
+					"0x4c04fac82913f01a8f01f6e15ff7e834ff2d9a9a1d8e9adffc7bd45692f4f9a"
+				]
+			}`,
+		},
 
 		"Invoke v1": {
 			hash:    "0x2897e3cec3e24e4d341df26b8cf1ab84ea1c01a051021836b36c6639145b497",