initial commit

.gitignore

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+mix_ping
+mix_ping_quic
+nimcache/
+nimbledeps/
+.agents/
+.codex
+nimble.paths
+nimble.develop

README.md

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+# libp2p Mix Example
+
+Standalone Nim example for running a libp2p Mix protocol ping simulation.
+
+## Quick Start
+
+Prerequisites:
+
+- Nim 2.0 or newer
+- Nimble
+- Git
+
+From a fresh clone:
+
+```bash
+nimble setup -l
+nim c -r mix_ping.nim
+```
+
+`nimble setup -l` enables project-local dependency mode, installs dependencies
+under `nimbledeps/`, and generates `nimble.paths` and `nimble.develop`.
+
+## Local Files
+
+The repository uses `config.nims` to keep Nim build output in the local
+`nimcache/` directory and to include `nimble.paths` when it exists.
+
+These files and directories are local artifacts and should not be committed:
+
+- `nimbledeps/`
+- `nimble.paths`
+- `nimble.develop`
+- `nimcache/`
+- `mix_ping`
+
+## Clean Rebuild
+
+To verify the project can be rebuilt from committed files:
+
+```bash
+rm -rf nimbledeps nimble.paths nimble.develop nimcache mix_ping
+nimble setup -l
+nim c -r mix_ping.nim
+```
+
+If `nimble setup -l` reports that it cannot determine the VCS revision, make at
+least one Git commit first, then rerun the command.

config.nims

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+switch("nimcache", "nimcache")
+
+# begin Nimble config (version 2)
+when withDir(thisDir(), system.fileExists("nimble.paths")):
+  include "nimble.paths"
+# end Nimble config

libp2p_mix_example.nimble

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+version = "0.1.0"
+author = "local"
+description = "Standalone libp2p mix protocol example"
+license = "MIT"
+srcDir = "."
+
+requires "nim >= 2.0.0"
+requires "libp2p >= 1.15.3"
+requires "chronicles >= 0.11.0"
+requires "chronos >= 4.2.2"
+requires "results >= 0.5.0"

mix_ping.nim

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+# SPDX-License-Identifier: Apache-2.0 OR MIT
+# Copyright (c) Status Research & Development GmbH
+
+## Mix Protocol Ping Example
+##
+## This example demonstrates using the Mix protocol with the Ping protocol.
+## It creates a set of mix nodes that form an anonymous overlay network,
+## then sends a ping through the mix network to a destination node and
+## receives the response via Single Use Reply Blocks (SURBs).
+
+{.used.}
+
+import chronicles, chronos, results
+import std/[strformat, sequtils]
+import libp2p/[
+    protocols/mix,
+    protocols/mix/mix_protocol,
+    protocols/mix/curve25519,
+    protocols/ping,
+    peerid,
+    multiaddress,
+    switch,
+    builders,
+    crypto/crypto,
+    crypto/secp,
+  ]
+
+const NumMixNodes = 10
+
+proc createSwitch(
+    multiAddr: MultiAddress, libp2pPrivKey: Opt[SkPrivateKey] = Opt.none(SkPrivateKey)
+): Switch =
+  var rng = newRng()
+  let skkey = libp2pPrivKey.valueOr(SkKeyPair.random(rng[]).seckey)
+  let privKey = PrivateKey(scheme: Secp256k1, skkey: skkey)
+  newStandardSwitchBuilder(privKey = Opt.some(privKey), addrs = multiAddr).build()
+
+proc mixPingSimulation() {.async: (raises: [Exception]).} =
+  let mixNodeInfos = MixNodeInfo.generateRandomMany(NumMixNodes)
+  var switches: seq[Switch] = @[]
+  var mixProtos: seq[MixProtocol] = @[]
+
+  # Set up mix protocols on each mix node
+  for nodeInfo in mixNodeInfos:
+    var switch = createSwitch(nodeInfo.multiAddr, Opt.some(nodeInfo.libp2pPrivKey))
+    let proto = MixProtocol.new(nodeInfo, switch)
+
+    # Populate nodePool with all other nodes' public info
+    proto.nodePool.add(mixNodeInfos.includeAllExcept(nodeInfo))
+
+    # Register how to read ping responses (32 bytes exactly)
+    proto.registerDestReadBehavior(PingCodec, readExactly(32))
+    switch.mount(proto)
+
+    switches.add(switch)
+    mixProtos.add(proto)
+
+  defer:
+    await switches.mapIt(it.stop()).allFutures()
+
+  # Create a destination node (not part of the mix network)
+  let destNode = createSwitch(MultiAddress.init("/ip4/0.0.0.0/tcp/0").tryGet())
+  defer:
+    await destNode.stop()
+
+  let pingProto = Ping.new()
+  destNode.mount(pingProto)
+
+  # Start all switches
+  await switches.mapIt(it.start()).allFutures()
+  await destNode.start()
+
+  # Pick sender (first mix node) and send ping through the mix network
+  let senderIndex = 0
+
+  info "Sending ping through mix network",
+    sender = switches[senderIndex].peerInfo.peerId,
+    destination = destNode.peerInfo.peerId
+
+  # Create a connection through the mix network
+  let conn = mixProtos[senderIndex]
+    .toConnection(
+      MixDestination.init(destNode.peerInfo.peerId, destNode.peerInfo.addrs[0]),
+      PingCodec,
+      MixParameters(expectReply: Opt.some(true), numSurbs: Opt.some(byte(1))),
+    )
+    .expect("could not build connection")
+
+  # Send ping and wait for response through the mix network
+  let response = await pingProto.ping(conn)
+  await conn.close()
+
+  info "Ping response received through mix network", rtt = response
+
+when isMainModule:
+  waitFor(mixPingSimulation())