add bench for handshake

shared/dnet/bench.txt

@@ -0,0 +1,7 @@
+goos: linux
+goarch: amd64
+pkg: koti.casa/numenor-labs/dsfx/shared/dnet
+cpu: Intel(R) Core(TM) Ultra 9 185H
+BenchmarkHandshake-22    	     537	   2179739 ns/op
+PASS
+ok  	koti.casa/numenor-labs/dsfx/shared/dnet	1.182s

shared/dnet/handshake_test.go

@@ -4,7 +4,9 @@ import (
 	"bytes"
 	"context"
 	"crypto/ecdsa"
+	"fmt"
 	"net"
+	"os"
 	"sync"
 	"testing"
 
@@ -79,3 +81,61 @@ func TestHandshake(t *testing.T) {
 		return
 	}
 }
+
+func BenchmarkHandshake(b *testing.B) {
+	for b.Loop() {
+		if err := runSimulation(); err != nil {
+			fmt.Fprint(os.Stderr, err)
+		}
+	}
+}
+
+func runSimulation() error {
+	ctx := context.Background()
+
+	// alice, represented by an ecdsa key pair.
+	alice, _ := dcrypto.GenerateSigningKey()
+	// bob, also represented by an ecdsa key pair.
+	bob, _ := dcrypto.GenerateSigningKey()
+
+	var (
+		// the secret that alice should arrive at on her own
+		// aliceSecret []byte
+		// any errors produce by alice
+		aliceErr error
+		// alice's public key as discovered by bob
+		// discoveredAlicePublicKey *ecdsa.PublicKey
+
+		// the secret that bob should arrive at on his own
+		// bobSecret []byte
+		// any errors produce by bob
+		bobErr error
+	)
+
+	// Create a network pipe to simulate a network connection between alice and bob.
+	client, server := net.Pipe()
+	defer client.Close()
+	defer server.Close()
+
+	// Run the handshake in parallel so both sides can proceed concurrently.
+	// Since they're talking through the network pipe, the entire process should
+	// be simulated as if it were a real network connection.
+	var wg sync.WaitGroup
+	wg.Add(2)
+	go func() {
+		_, aliceErr = dnet.Handshake(ctx, client, alice, &bob.PublicKey)
+		wg.Done()
+	}()
+	go func() {
+		_, _, bobErr = dnet.AcceptHandshake(ctx, server, bob)
+		wg.Done()
+	}()
+	wg.Wait()
+	if aliceErr != nil {
+		return aliceErr
+	}
+	if bobErr != nil {
+		return bobErr
+	}
+	return nil
+}