From f5ce6b0749023fb5310f04ef6c913485d6e2e5a3 Mon Sep 17 00:00:00 2001
From: Aurora Gaffney <aurora@blinklabs.io>
Date: Wed, 10 Apr 2024 15:58:21 -0500
Subject: [PATCH] feat: initial tx-submission server support (#5)

---
 listener.go     | 24 +++++++++++++++---
 txsubmission.go | 65 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+), 3 deletions(-)
 create mode 100644 txsubmission.go

diff --git a/listener.go b/listener.go
index 22c7d92..028c81b 100644
--- a/listener.go
+++ b/listener.go
@@ -20,6 +20,7 @@ import (
 
 	ouroboros "github.com/blinklabs-io/gouroboros"
 	"github.com/blinklabs-io/gouroboros/protocol/peersharing"
+	"github.com/blinklabs-io/gouroboros/protocol/txsubmission"
 )
 
 type ListenerConfig struct {
@@ -33,17 +34,34 @@ func (n *Node) startListener(l ListenerConfig) {
 		ouroboros.WithNetworkMagic(n.config.networkMagic),
 		ouroboros.WithNodeToNode(!l.UseNtC),
 		ouroboros.WithServer(true),
-		ouroboros.WithPeerSharing(n.config.peerSharing),
-		// TODO: add protocol configs to configure callback functions
 	}
-	if n.config.peerSharing {
+	if l.UseNtC {
+		// Node-to-client
 		defaultConnOpts = append(
 			defaultConnOpts,
+			// TODO: add localtxsubmission
+			// TODO: add localstatequery
+			// TODO: add localtxmonitor
+		)
+	} else {
+		// Node-to-node
+		defaultConnOpts = append(
+			defaultConnOpts,
+			// Peer sharing
+			ouroboros.WithPeerSharing(n.config.peerSharing),
 			ouroboros.WithPeerSharingConfig(
 				peersharing.NewConfig(
 					peersharing.WithShareRequestFunc(n.peersharingShareRequest),
 				),
 			),
+			// TxSubmission
+			ouroboros.WithTxSubmissionConfig(
+				txsubmission.NewConfig(
+					txsubmission.WithInitFunc(n.txsubmissionServerInit),
+				),
+			),
+			// TODO: add chain-sync
+			// TODO: add block-fetch
 		)
 	}
 	for {
diff --git a/txsubmission.go b/txsubmission.go
new file mode 100644
index 0000000..4920f6b
--- /dev/null
+++ b/txsubmission.go
@@ -0,0 +1,65 @@
+// Copyright 2024 Blink Labs Software
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package node
+
+import (
+	"fmt"
+
+	"github.com/blinklabs-io/gouroboros/ledger"
+	"github.com/blinklabs-io/gouroboros/protocol/txsubmission"
+)
+
+const (
+	txsubmissionRequestTxIdsCount = 10 // Number of TxIds to request from peer at one time
+)
+
+func (n *Node) txsubmissionServerInit(ctx txsubmission.CallbackContext) error {
+	// Start async loop to request transactions from the peer's mempool
+	go func() {
+		for {
+			// Request available TX IDs (era and TX hash) and sizes
+			// We make the request blocking to avoid looping on our side
+			txIds, err := ctx.Server.RequestTxIds(true, txsubmissionRequestTxIdsCount)
+			if err != nil {
+				n.config.logger.Error(fmt.Sprintf("failed to request TxIds: %s", err))
+				return
+			}
+			if len(txIds) > 0 {
+				// Unwrap inner TxId from TxIdAndSize
+				var requestTxIds []txsubmission.TxId
+				for _, txId := range txIds {
+					requestTxIds = append(requestTxIds, txId.TxId)
+				}
+				// Request TX content for TxIds from above
+				txs, err := ctx.Server.RequestTxs(requestTxIds)
+				if err != nil {
+					n.config.logger.Error(fmt.Sprintf("failed to request Txs: %s", err))
+					return
+				}
+				for _, txBody := range txs {
+					// Decode TX from CBOR
+					tx, err := ledger.NewTransactionFromCbor(uint(txBody.EraId), txBody.TxBody)
+					if err != nil {
+						n.config.logger.Error(fmt.Sprintf("failed to parse transaction CBOR: %s", err))
+						return
+					}
+					n.config.logger.Debug(fmt.Sprintf("received TX %s via TxSubmission", tx.Hash()))
+					// TODO: add hooks to do something with TX
+				}
+			}
+		}
+	}()
+	return nil
+}