DAS: add minimal DAS test

WIP, still not sampling but going through all samples

Signed-off-by: Csaba Kiraly <csaba.kiraly@gmail.com>

das/das.nim

@@ -0,0 +1,123 @@
+import
+  std/[options, sequtils],
+  asynctest,
+  bearssl/rand,
+  chronicles,
+  chronos,
+  nimcrypto,
+  libp2p/crypto/[crypto, secp],
+  libp2p/[multiaddress, multicodec, multihash, routing_record, signed_envelope],
+  libp2pdht/dht,
+  libp2pdht/discv5/crypto as dhtcrypto,
+  libp2pdht/discv5/protocol as discv5_protocol,
+  stew/byteutils,
+  tests/dht/test_helper
+
+logScope:
+  topics = "DAS emulator"
+
+proc bootstrapNodes(
+    nodecount: int,
+    bootnodes: seq[SignedPeerRecord],
+    rng = newRng(),
+    delay: int = 0
+  ) : Future[seq[(discv5_protocol.Protocol, PrivateKey)]] {.async.} =
+
+  debug "---- STARTING BOOSTRAPS ---"
+  for i in 0..<nodecount:
+    try:
+      let privKey = PrivateKey.example(rng)
+      let node = initDiscoveryNode(rng, privKey, localAddress(20302 + i), bootnodes)
+      await node.start()
+      result.add((node, privKey))
+      if delay > 0:
+        await sleepAsync(chronos.milliseconds(delay))
+    except TransportOsError as e:
+      echo "skipping node ",i ,":", e.msg
+
+  #await allFutures(result.mapIt(it.bootstrap())) # this waits for bootstrap based on bootENode, which includes bonding with all its ping pongs
+
+proc bootstrapNetwork(
+    nodecount: int,
+    rng = newRng(),
+    delay: int = 0
+  ) : Future[seq[(discv5_protocol.Protocol, PrivateKey)]] {.async.} =
+
+  let
+    bootNodeKey = PrivateKey.fromHex(
+      "a2b50376a79b1a8c8a3296485572bdfbf54708bb46d3c25d73d2723aaaf6a617")
+      .expect("Valid private key hex")
+    bootNodeAddr = localAddress(20301)
+    bootNode = initDiscoveryNode(rng, bootNodeKey, bootNodeAddr, @[]) # just a shortcut for new and open
+
+  #waitFor bootNode.bootstrap()  # immediate, since no bootnodes are defined above
+
+  var res = await bootstrapNodes(nodecount - 1,
+                           @[bootnode.localNode.record],
+                           rng,
+                           delay)
+  res.insert((bootNode, bootNodeKey), 0)
+  return res
+
+proc toNodeId(data: openArray[byte]): NodeId =
+  readUintBE[256](keccak256.digest(data).data)
+
+proc segmentData(s: int, segmentsize: int) : seq[byte] =
+  result = newSeq[byte](segmentsize)
+  result[0] = byte(s mod 256)
+
+when isMainModule:
+  proc main() {.async.} =
+    let
+      nodecount = 5
+      delay_pernode = 10 # in millisec
+      delay_init = 2*1000 # in millisec
+      blocksize = 16
+      segmentsize = 10
+      samplesize = 3
+
+    var
+      rng: ref HmacDrbgContext
+      nodes: seq[(discv5_protocol.Protocol, PrivateKey)]
+      node0: discv5_protocol.Protocol
+      privKey0: PrivateKey
+      signedPeerRec0: SignedPeerRecord
+      peerRec0: PeerRecord
+      segmentIDs = newSeq[NodeId](blocksize)
+
+    # start network
+    rng = newRng()
+    nodes = await bootstrapNetwork(nodecount=nodecount, delay=delay_pernode)
+    (node0, privKey0) = nodes[0]
+    signedPeerRec0 = privKey0.toSignedPeerRecord
+    peerRec0 = signedPeerRec0.data
+
+    # wait for network to settle
+    await sleepAsync(chronos.milliseconds(delay_init))
+
+    # generate block and push data
+    for s in 0 ..< blocksize:
+      let
+        segment = segmentData(s, segmentsize)
+        key = toNodeId(segment)
+
+      segmentIDs[s] = key
+
+      let addedTo = await node0.addValue(key, segment)
+      debug "Value added to: ", addedTo
+
+    # sample
+    for n in 1 ..< nodecount:
+      for s in 0 ..< blocksize:
+        let startTime = Moment.now()
+        let res = await nodes[n][0].getValue(segmentIDs[s])
+        let pass = res.isOk()
+        info "sample", pass, by = n, sample = s, time = Moment.now() - startTime
+
+  waitfor main()
+
+# proc teardownAll() =
+#     for (n, _) in nodes: # if last test is enabled, we need nodes[1..^1] here
+#       await n.closeWait()
+
+