From a63000f602bdb6dd8fc08f936675e66ab3ce7f1c Mon Sep 17 00:00:00 2001
From: Mark Spanbroek <mark@spanbroek.net>
Date: Thu, 28 Jan 2021 17:40:16 +0100
Subject: [PATCH] Exchange objects between peers using bitswap

---
 ipfs/bitswap.nim           | 48 ++++++++++++++++++++++++++++++++++++++
 ipfs/bitswap/exchange.nim  | 38 ++++++++++++++++++++++++++++++
 tests/ipfs/testBitswap.nim | 41 ++++++++++++++++++++++++++++++++
 tests/testAll.nim          |  1 +
 4 files changed, 128 insertions(+)
 create mode 100644 ipfs/bitswap.nim
 create mode 100644 ipfs/bitswap/exchange.nim
 create mode 100644 tests/ipfs/testBitswap.nim

diff --git a/ipfs/bitswap.nim b/ipfs/bitswap.nim
new file mode 100644
index 00000000..ca8914af
--- /dev/null
+++ b/ipfs/bitswap.nim
@@ -0,0 +1,48 @@
+import std/options
+import pkg/chronos
+import pkg/libp2p/cid
+import ./ipfsobject
+import ./repo
+import ./p2p/switch
+import ./bitswap/protocol
+import ./bitswap/exchange
+
+export options
+export Cid
+export Switch
+
+type
+  Bitswap* = ref object
+    repo: Repo
+    switch: Switch
+    exchanges: seq[Exchange] # TODO: never cleaned
+
+proc startExchange(bitswap: Bitswap, stream: BitswapStream) =
+  let exchange = Exchange.start(bitswap.repo, stream)
+  bitswap.exchanges.add(exchange)
+
+proc start*(_: type Bitswap, switch: Switch, repo = Repo()): Bitswap =
+  let bitswap = Bitswap(repo: repo, switch: switch)
+  let protocol = BitswapProtocol.new()
+  proc acceptLoop {.async.} =
+    while true:
+      let stream = await protocol.accept()
+      bitswap.startExchange(stream)
+  asyncSpawn acceptLoop()
+  switch.mount(protocol)
+  bitswap
+
+proc connect*(bitswap: Bitswap, peer: PeerInfo) {.async.} =
+  let stream = await bitswap.switch.dial(peer, BitswapProtocol)
+  bitswap.startExchange(stream)
+
+proc store*(bitswap: Bitswap, obj: IpfsObject) =
+  bitswap.repo.store(obj)
+
+proc retrieve*(bitswap: Bitswap, cid: Cid): Future[Option[IpfsObject]] {.async.} =
+  result = bitswap.repo.retrieve(cid)
+  if result.isNone:
+    for exchange in bitswap.exchanges:
+      await exchange.want(cid)
+    await sleepAsync(1.seconds) # TODO
+    result = bitswap.repo.retrieve(cid)
diff --git a/ipfs/bitswap/exchange.nim b/ipfs/bitswap/exchange.nim
new file mode 100644
index 00000000..4c32c1d8
--- /dev/null
+++ b/ipfs/bitswap/exchange.nim
@@ -0,0 +1,38 @@
+import pkg/chronos
+import pkg/libp2p/cid
+import ../repo
+import ./stream
+import ./messages
+
+type Exchange* = object
+  repo: Repo
+  stream: BitswapStream
+
+proc want*(exchange: Exchange, cid: Cid) {.async.} =
+  await exchange.stream.write(Message.want(cid))
+
+proc send*(exchange: Exchange, obj: IpfsObject) {.async.} =
+  await exchange.stream.write(Message.send(obj.data))
+
+proc handlePayload(exchange: Exchange, message: Message) {.async.} =
+  for bloc in message.payload:
+    let obj = IpfsObject(data: bloc.data)
+    exchange.repo.store(obj)
+
+proc handleWants(exchange: Exchange, message: Message) {.async.} =
+  for want in message.wantlist.entries:
+    let cid = Cid.init(want.`block`).get()
+    let obj = exchange.repo.retrieve(cid)
+    if obj.isSome:
+      await exchange.send(obj.get())
+
+proc readLoop(exchange: Exchange) {.async.} =
+  while true:
+    let message = await exchange.stream.read()
+    await exchange.handlePayload(message)
+    await exchange.handleWants(message)
+
+proc start*(_: type Exchange, repo: Repo, stream: BitswapStream): Exchange =
+  let exchange = Exchange(repo: repo, stream: stream)
+  asyncSpawn exchange.readLoop()
+  exchange
diff --git a/tests/ipfs/testBitswap.nim b/tests/ipfs/testBitswap.nim
new file mode 100644
index 00000000..d93fc5ba
--- /dev/null
+++ b/tests/ipfs/testBitswap.nim
@@ -0,0 +1,41 @@
+import pkg/chronos
+import pkg/asynctest
+import pkg/ipfs/ipfsobject
+import pkg/ipfs/p2p/switch
+import pkg/ipfs/bitswap
+
+suite "bitswap":
+
+  let address = MultiAddress.init("/ip4/127.0.0.1/tcp/40981").get()
+  let obj = IpfsObject(data: @[1'u8, 2'u8, 3'u8])
+
+  var bitswap1, bitswap2: Bitswap
+  var peer1, peer2: Switch
+
+  setup:
+    peer1 = Switch.create()
+    peer2 = Switch.create()
+    peer1.peerInfo.addrs.add(address)
+    discard await peer1.start()
+    discard await peer2.start()
+    bitswap1 = Bitswap.start(peer1)
+    bitswap2 = Bitswap.start(peer2)
+
+  teardown:
+    await peer1.stop()
+    await peer2.stop()
+
+  test "stores ipfs objects":
+    bitswap1.store(obj)
+
+  test "retrieves local objects":
+    bitswap1.store(obj)
+    check (await bitswap1.retrieve(obj.cid)).get() == obj
+
+  test "signals retrieval failure":
+    check (await bitswap1.retrieve(obj.cid)).isNone
+
+  test "retrieves objects from network":
+    bitswap1.store(obj)
+    await bitswap2.connect(peer1.peerInfo)
+    check (await bitswap2.retrieve(obj.cid)).get() == obj
diff --git a/tests/testAll.nim b/tests/testAll.nim
index cb61c65b..5b356fcd 100644
--- a/tests/testAll.nim
+++ b/tests/testAll.nim
@@ -5,6 +5,7 @@ import ./ipfs/testDhtRouting
 import ./ipfs/testProtobuf
 import ./ipfs/testBitswapMessages
 import ./ipfs/testBitswapProtocol
+import ./ipfs/testBitswap
 import ./ipfs/testIpfs
 
 {.warning[UnusedImport]: off.}