bug: fix multiple connections to same listen port hanging CLI (#5939)

* fix: return error when listen port already in use

* add err handling for proxy start

* add listen port and DefaultClientPort tests

* add err handling for listen info

internal/cmd/commands/connect/connect.go

@@ -434,6 +434,7 @@ func (c *Command) Run(args []string) (retCode int) {
 		c.PrintCliError(fmt.Errorf("Error parsing listen address: %w", err))
 		return base.CommandCliError
 	}
+
 	listenAddr = netip.AddrPortFrom(addr, uint16(c.flagListenPort))
 
 	connsLeftCh := make(chan int32)
@@ -458,7 +459,10 @@ func (c *Command) Run(args []string) (retCode int) {
 	proxyError := new(atomic.Error)
 	go func() {
 		defer close(clientProxyCloseCh)
-		proxyError.Store(clientProxy.Start())
+		if err = clientProxy.Start(); err != nil {
+			c.proxyCancel()
+			proxyError.Store(err)
+		}
 	}()
 	go func() {
 		defer close(connCountCloseCh)
@@ -482,7 +486,15 @@ func (c *Command) Run(args []string) (retCode int) {
 		// The only way a user will be able to connect to the session is by
 		// connecting directly to the port and address we report to them here.
 
-		proxyAddr := clientProxy.ListenerAddress(context.Background())
+		proxyAddr := clientProxy.ListenerAddress(c.proxyCtx)
+		if proxyAddr == "" {
+			if err := proxyError.Load(); err != nil {
+				c.PrintCliError(fmt.Errorf("Error starting proxy: %w", err))
+				return base.CommandCliError
+			}
+			c.PrintCliError(fmt.Errorf("Error starting proxy: no address returned"))
+			return base.CommandCliError
+		}
 		var clientProxyHost, clientProxyPort string
 		clientProxyHost, clientProxyPort, err = util.SplitHostPort(proxyAddr)
 		if err != nil && !errors.Is(err, util.ErrMissingPort) {

testing/internal/e2e/tests/base/target_tcp_connect_listen_port_test.go

@@ -0,0 +1,134 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: BUSL-1.1
+
+package base_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/hashicorp/boundary/internal/session"
+	"github.com/hashicorp/boundary/internal/target"
+	"github.com/hashicorp/boundary/testing/internal/e2e"
+	"github.com/hashicorp/boundary/testing/internal/e2e/boundary"
+)
+
+// TestCliTcpTargetConnectListenPort uses the boundary cli to create a target and
+// connect to it multiple times on the same listen port. The cli should return an error when
+// a port is already in use.
+func TestCliTcpTargetConnectListenPort(t *testing.T) {
+	e2e.MaybeSkipTest(t)
+	c, err := loadTestConfig()
+	require.NoError(t, err)
+
+	ctx := context.Background()
+	boundary.AuthenticateAdminCli(t, ctx)
+	orgId, err := boundary.CreateOrgCli(t, ctx)
+	require.NoError(t, err)
+	t.Cleanup(func() {
+		ctx := context.Background()
+		boundary.AuthenticateAdminCli(t, ctx)
+		output := e2e.RunCommand(ctx, "boundary", e2e.WithArgs("scopes", "delete", "-id", orgId))
+		require.NoError(t, output.Err, string(output.Stderr))
+	})
+	projectId, err := boundary.CreateProjectCli(t, ctx, orgId)
+	require.NoError(t, err)
+	targetId, err := boundary.CreateTargetCli(t, ctx, projectId, c.TargetPort,
+		target.WithAddress(c.TargetAddress),
+	)
+	require.NoError(t, err)
+
+	// Connect to target with client port 3333
+	const ListenPort = "3333"
+
+	ctxCancel, cancel := context.WithCancel(ctx)
+	sessionChannel := make(chan *e2e.CommandResult)
+
+	go func() {
+		sessionChannel <- e2e.RunCommand(ctxCancel, "boundary",
+			e2e.WithArgs(
+				"connect",
+				"-target-id", targetId,
+				"-listen-port", ListenPort,
+			),
+		)
+	}()
+	t.Cleanup(cancel)
+
+	s := boundary.WaitForSessionCli(t, ctx, projectId)
+	boundary.WaitForSessionStatusCli(t, ctx, s.Id, session.StatusPending.String())
+	t.Logf("Successfully connected to target with listen port %s", ListenPort)
+
+	t.Logf("Starting new connection to target with same listen port %s", ListenPort)
+	output := e2e.RunCommand(ctx, "boundary",
+		e2e.WithArgs(
+			"connect",
+			"-target-id", targetId,
+			"-listen-port", ListenPort,
+		),
+	)
+
+	require.Error(t, output.Err, "Expected error when connecting to target with same listen port")
+	require.Contains(t, string(output.Stderr), "address already in use")
+	require.Equal(t, 2, output.ExitCode)
+}
+
+// TestCliTcpTargetConnectDefaultClientPort uses the boundary cli to create a target and
+// connect to it multiple times on the same client port. The test is similar to the one above,
+// but sets DefaultClientPort instead of ListenPort
+func TestCliTcpTargetConnectDefaultClientPort(t *testing.T) {
+	const DefaultClientPort = 3333
+	e2e.MaybeSkipTest(t)
+	c, err := loadTestConfig()
+	require.NoError(t, err)
+
+	ctx := context.Background()
+	boundary.AuthenticateAdminCli(t, ctx)
+	orgId, err := boundary.CreateOrgCli(t, ctx)
+	require.NoError(t, err)
+	t.Cleanup(func() {
+		ctx := context.Background()
+		boundary.AuthenticateAdminCli(t, ctx)
+		output := e2e.RunCommand(ctx, "boundary", e2e.WithArgs("scopes", "delete", "-id", orgId))
+		require.NoError(t, output.Err, string(output.Stderr))
+	})
+	projectId, err := boundary.CreateProjectCli(t, ctx, orgId)
+	require.NoError(t, err)
+	targetId, err := boundary.CreateTargetCli(t, ctx, projectId, c.TargetPort,
+		target.WithAddress(c.TargetAddress),
+		target.WithDefaultClientPort(DefaultClientPort),
+	)
+	require.NoError(t, err)
+
+	// Connect to target with DefaultClientPort set
+	ctxCancel, cancel := context.WithCancel(ctx)
+	sessionChannel := make(chan *e2e.CommandResult)
+
+	go func() {
+		sessionChannel <- e2e.RunCommand(ctxCancel, "boundary",
+			e2e.WithArgs(
+				"connect",
+				"-target-id", targetId,
+			),
+		)
+	}()
+	t.Cleanup(cancel)
+
+	s := boundary.WaitForSessionCli(t, ctx, projectId)
+	boundary.WaitForSessionStatusCli(t, ctx, s.Id, session.StatusPending.String())
+	t.Logf("Successfully connected to target with client port %d", DefaultClientPort)
+
+	t.Logf("Starting new connection to target on client port %d", DefaultClientPort)
+	output := e2e.RunCommand(ctx, "boundary",
+		e2e.WithArgs(
+			"connect",
+			"-target-id", targetId,
+		),
+	)
+
+	require.Error(t, output.Err, "Expected error when connecting to target with same listen port")
+	require.Contains(t, string(output.Stderr), "address already in use")
+	require.Equal(t, 2, output.ExitCode)
+}