From 9304f5575ea4c578d1316c2cf695a06b65c88dbe Mon Sep 17 00:00:00 2001
From: Adin Schmahmann <adin.schmahmann@gmail.com>
Date: Fri, 28 Aug 2020 15:31:13 -0400
Subject: [PATCH] feat: add advanced V1ProtocolOverride option to be used by
 legacy networks

---
 dht.go         |  5 +++++
 dht_options.go | 39 ++++++++++++++++++++++++++-------------
 dht_test.go    | 31 +++++++++++++++++++++++++++++++
 3 files changed, 62 insertions(+), 13 deletions(-)

diff --git a/dht.go b/dht.go
index a662d8ed8..b599cb6bd 100644
--- a/dht.go
+++ b/dht.go
@@ -260,6 +260,11 @@ func makeDHT(ctx context.Context, h host.Host, cfg config) (*IpfsDHT, error) {
 	var protocols, serverProtocols []protocol.ID
 
 	v1proto := cfg.protocolPrefix + kad1
+
+	if cfg.v1ProtocolOverride != "" {
+		v1proto = cfg.v1ProtocolOverride
+	}
+
 	protocols = []protocol.ID{v1proto}
 	serverProtocols = []protocol.ID{v1proto}
 
diff --git a/dht_options.go b/dht_options.go
index 7e2ac1b76..c4b08c03a 100644
--- a/dht_options.go
+++ b/dht_options.go
@@ -39,19 +39,20 @@ const DefaultPrefix protocol.ID = "/ipfs"
 
 // Options is a structure containing all the options that can be used when constructing a DHT.
 type config struct {
-	datastore        ds.Batching
-	validator        record.Validator
-	validatorChanged bool // if true implies that the validator has been changed and that defaults should not be used
-	mode             ModeOpt
-	protocolPrefix   protocol.ID
-	bucketSize       int
-	concurrency      int
-	resiliency       int
-	maxRecordAge     time.Duration
-	enableProviders  bool
-	enableValues     bool
-	providersOptions []providers.Option
-	queryPeerFilter  QueryFilterFunc
+	datastore          ds.Batching
+	validator          record.Validator
+	validatorChanged   bool // if true implies that the validator has been changed and that defaults should not be used
+	mode               ModeOpt
+	protocolPrefix     protocol.ID
+	v1ProtocolOverride protocol.ID
+	bucketSize         int
+	concurrency        int
+	resiliency         int
+	maxRecordAge       time.Duration
+	enableProviders    bool
+	enableValues       bool
+	providersOptions   []providers.Option
+	queryPeerFilter    QueryFilterFunc
 
 	routingTable struct {
 		refreshQueryTimeout time.Duration
@@ -275,6 +276,18 @@ func ProtocolExtension(ext protocol.ID) Option {
 	}
 }
 
+// V1ProtocolOverride overrides the protocolID used for /kad/1.0.0 with another. This is an
+// advanced feature, and should only be used to handle legacy networks that have not been
+// using protocolIDs of the form /app/kad/1.0.0.
+//
+// This option will override and ignore the ProtocolPrefix and ProtocolExtension options
+func V1ProtocolOverride(proto protocol.ID) Option {
+	return func(c *config) error {
+		c.v1ProtocolOverride = proto
+		return nil
+	}
+}
+
 // BucketSize configures the bucket size (k in the Kademlia paper) of the routing table.
 //
 // The default value is 20.
diff --git a/dht_test.go b/dht_test.go
index 42894a52b..a20f5c90c 100644
--- a/dht_test.go
+++ b/dht_test.go
@@ -1867,6 +1867,37 @@ func TestInvalidKeys(t *testing.T) {
 	}
 }
 
+func TestV1ProtocolOverride(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	d1 := setupDHT(ctx, t, false, V1ProtocolOverride("/myproto") )
+	d2 := setupDHT(ctx, t, false, V1ProtocolOverride("/myproto") )
+	d3 := setupDHT(ctx, t, false, V1ProtocolOverride("/myproto2"))
+	d4 := setupDHT(ctx, t, false)
+
+	dhts := []*IpfsDHT{d1,d2,d3,d4}
+
+	for i, dout := range dhts {
+		for _, din := range dhts[i+1:] {
+			connectNoSync(t, ctx, dout, din)
+		}
+	}
+
+	wait(t, ctx, d1, d2)
+	wait(t, ctx, d2, d1)
+
+	time.Sleep(time.Second)
+
+	if d1.RoutingTable().Size() != 1 || d2.routingTable.Size() != 1 {
+		t.Fatal("should have one peer in the routing table")
+	}
+
+	if d3.RoutingTable().Size() > 0  || d4.RoutingTable().Size() > 0{
+		t.Fatal("should have an empty routing table")
+	}
+}
+
 func TestRoutingFilter(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()