fix SSH ping CPU spin and Linux releases

internal/sshclient/sshclient_test.go

@@ -1,6 +1,8 @@
 package sshclient
 
 import (
+	"crypto/ed25519"
+	"crypto/rand"
 	"net"
 	"testing"
 	"time"
@@ -57,3 +59,94 @@ func TestJumpHostClientConfigUsesFinalHostKeyCallback(t *testing.T) {
 		t.Fatal("final host key callback was not used")
 	}
 }
+
+func TestPingReturnsAfterSSHTransportCloses(t *testing.T) {
+	_, privateKey, err := ed25519.GenerateKey(rand.Reader)
+	if err != nil {
+		t.Fatalf("GenerateKey() error = %v", err)
+	}
+	signer, err := ssh.NewSignerFromKey(privateKey)
+	if err != nil {
+		t.Fatalf("NewSignerFromKey() error = %v", err)
+	}
+
+	serverConfig := &ssh.ServerConfig{NoClientAuth: true}
+	serverConfig.AddHostKey(signer)
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("Listen() error = %v", err)
+	}
+	t.Cleanup(func() { _ = listener.Close() })
+
+	serverReady := make(chan *ssh.ServerConn, 1)
+	serverErrors := make(chan error, 1)
+	go func() {
+		conn, acceptErr := listener.Accept()
+		if acceptErr != nil {
+			serverErrors <- acceptErr
+			return
+		}
+		serverConn, _, _, handshakeErr := ssh.NewServerConn(conn, serverConfig)
+		if handshakeErr != nil {
+			_ = conn.Close()
+			serverErrors <- handshakeErr
+			return
+		}
+		serverReady <- serverConn
+	}()
+
+	conn, err := net.DialTimeout("tcp", listener.Addr().String(), 2*time.Second)
+	if err != nil {
+		t.Fatalf("DialTimeout() error = %v", err)
+	}
+	clientConn, channels, requests, err := ssh.NewClientConn(conn, listener.Addr().String(), &ssh.ClientConfig{
+		User:            "test",
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(), // Test server uses an ephemeral key.
+	})
+	if err != nil {
+		_ = conn.Close()
+		t.Fatalf("NewClientConn() error = %v", err)
+	}
+	rawClient := ssh.NewClient(clientConn, channels, requests)
+
+	var serverConn *ssh.ServerConn
+	select {
+	case serverConn = <-serverReady:
+	case serverErr := <-serverErrors:
+		t.Fatalf("SSH server handshake error = %v", serverErr)
+	case <-time.After(2 * time.Second):
+		t.Fatal("timed out waiting for SSH server handshake")
+	}
+
+	client := NewClient(&models.Profile{})
+	client.mu.Lock()
+	client.sshClient = rawClient
+	client.connected = true
+	client.mu.Unlock()
+	t.Cleanup(func() { _ = client.Close() })
+
+	if err := serverConn.Close(); err != nil {
+		t.Fatalf("server Close() error = %v", err)
+	}
+	waitDone := make(chan error, 1)
+	go func() { waitDone <- rawClient.Wait() }()
+	select {
+	case <-waitDone:
+	case <-time.After(2 * time.Second):
+		t.Fatal("timed out waiting for SSH transport to close")
+	}
+
+	pingDone := make(chan error, 1)
+	go func() {
+		_, pingErr := client.Ping()
+		pingDone <- pingErr
+	}()
+	select {
+	case pingErr := <-pingDone:
+		if pingErr == nil {
+			t.Fatal("Ping() succeeded after the SSH transport closed")
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatal("Ping() did not return after the SSH transport closed")
+	}
+}