From de1e143fb27d6675c1e3a7a236debcf816f7f2b2 Mon Sep 17 00:00:00 2001
From: dozyio <github@dozy.io>
Date: Sun, 9 Nov 2025 20:24:10 +0000
Subject: [PATCH] feat: dht findpeer

---
 lib/dht.go | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 main.go    | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 102 insertions(+), 1 deletion(-)

diff --git a/lib/dht.go b/lib/dht.go
index 0bbb82e..9cda62e 100644
--- a/lib/dht.go
+++ b/lib/dht.go
@@ -2,8 +2,11 @@ package vole
 
 import (
 	"context"
+	"fmt"
 	"time"
 
+	"github.com/libp2p/go-libp2p"
+	dht "github.com/libp2p/go-libp2p-kad-dht"
 	"github.com/libp2p/go-libp2p/core/host"
 	"github.com/libp2p/go-libp2p/core/network"
 	"github.com/libp2p/go-libp2p/core/peer"
@@ -107,6 +110,53 @@ func DhtGetClosestPeers(ctx context.Context, key []byte, proto protocol.ID, ma m
 	return ais, nil
 }
 
+func DhtFindPeer(ctx context.Context, peerToFind peer.ID, bootstrappers []peer.AddrInfo) (*peer.AddrInfo, error) {
+	h, err := libp2p.New(libp2p.NoListenAddrs)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create host: %w", err)
+	}
+	defer h.Close()
+
+	dhtOpts := []dht.Option{
+		dht.Mode(dht.ModeClient),
+		dht.BootstrapPeers(bootstrappers...),
+	}
+
+	kademliaDHT, err := dht.New(ctx, h, dhtOpts...)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create dht client: %w", err)
+	}
+	defer kademliaDHT.Close()
+
+	if err = kademliaDHT.Bootstrap(ctx); err != nil {
+		return nil, fmt.Errorf("bootstrap failed: %w", err)
+	}
+
+	deadline := time.NewTimer(5 * time.Second)
+	defer deadline.Stop()
+
+	ticker := time.NewTicker(100 * time.Millisecond)
+	defer ticker.Stop()
+
+	for kademliaDHT.RoutingTable().Size() < 10 {
+		select {
+		case <-deadline.C:
+			return nil, fmt.Errorf("routing table warmup timed out (size=%d)", kademliaDHT.RoutingTable().Size())
+		case <-ctx.Done():
+			return nil, fmt.Errorf("routing table warmup canceled: %w (size=%d)", ctx.Err(), kademliaDHT.RoutingTable().Size())
+		case <-ticker.C:
+			// keep polling
+		}
+	}
+
+	peerInfo, err := kademliaDHT.FindPeer(ctx, peerToFind)
+	if err != nil {
+		return nil, fmt.Errorf("FindPeer failed: %w", err)
+	}
+
+	return &peerInfo, nil
+}
+
 func DhtPing(ctx context.Context, proto protocol.ID, ma multiaddr.Multiaddr) error {
 	ai, err := peer.AddrInfoFromP2pAddr(ma)
 	if err != nil {
diff --git a/main.go b/main.go
index 974dea1..dc733c7 100644
--- a/main.go
+++ b/main.go
@@ -12,6 +12,7 @@ import (
 	"github.com/urfave/cli/v2"
 
 	"github.com/ipfs/go-cid"
+	dht "github.com/libp2p/go-libp2p-kad-dht"
 	"github.com/libp2p/go-libp2p/core/peer"
 	"github.com/libp2p/go-libp2p/core/protocol"
 	"github.com/libp2p/go-libp2p/p2p/protocol/identify"
@@ -234,6 +235,56 @@ func main() {
 							},
 						},
 					},
+					{
+						Name:        "findpeer",
+						ArgsUsage:   "<peer-id> <optional-bootstrapper-multiaddr>",
+						Usage:       "findpeer resolves the multiaddrs for a peer ID",
+						Description: "creates a libp2p peer and sends DHT get closest peers requests until the peer is found. An optional bootstrapper can be provided, otherwise it falls back to the default bootstrappers",
+						Action: func(c *cli.Context) error {
+							if c.NArg() == 0 || c.NArg() > 2 {
+								return fmt.Errorf("invalid number of arguments")
+							}
+
+							peerIDStr := c.Args().Get(0)
+							bootstrappers := make([]peer.AddrInfo, 0)
+
+							if c.NArg() == 2 {
+								maStr := c.Args().Get(1)
+
+								ma, err := multiaddr.NewMultiaddr(maStr)
+								if err != nil {
+									return err
+								}
+
+								bootstrapper, err := peer.AddrInfoFromP2pAddr(ma)
+								if err != nil {
+									return fmt.Errorf("failed to parse bootstrapper multiaddr: %w", err)
+								}
+
+								bootstrappers = append(bootstrappers, *bootstrapper)
+
+							} else {
+								bootstrappers = dht.GetDefaultBootstrapPeerAddrInfos()
+							}
+
+							peerID, err := peer.Decode(peerIDStr)
+							if err != nil {
+								return err
+							}
+
+							ais, err := vole.DhtFindPeer(c.Context, peerID, bootstrappers)
+							if err != nil {
+								return err
+							}
+
+							for _, a := range ais.Addrs {
+								fmt.Println(a)
+							}
+
+							return nil
+						},
+						Flags: []cli.Flag{},
+					},
 					{
 						Name:        "ping",
 						ArgsUsage:   "<multiaddr>",
@@ -345,7 +396,6 @@ Note: may not work with some transports such as p2p-circuit (not applicable) and
 						Name:      "ping",
 						ArgsUsage: "<multiaddr>",
 						Flags: []cli.Flag{
-
 							&cli.BoolFlag{
 								Name:        "force-relay",
 								Usage:       `Ping the peer over a relay instead of a direct connection`,
@@ -440,6 +490,7 @@ var bitswapGetCmd = &cli.Command{
 		return vole.GetBitswapCID(root, ai)
 	},
 }
+
 var bitswapCheckCmd = &cli.Command{
 	Name:        "check",
 	ArgsUsage:   "<cid> <multiaddr>",