Lock client connections and update deadline handling

Add mutex locking for client connections to ensure thread safety. Introduce `HasConnection` method to check active connections and `UpdateDeadline` method to handle timeout updates. Refactor connection handling in `checkConn` and `tls` methods accordingly.

client.go

@@ -12,6 +12,7 @@ import (
 	"net"
 	"os"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/wneessen/go-mail/log"
@@ -87,6 +88,7 @@ type DialContextFunc func(ctx context.Context, network, address string) (net.Con
 
 // Client is the SMTP client struct
 type Client struct {
+	mutex sync.RWMutex
 	// connection is the net.Conn that the smtp.Client is based on
 	connection net.Conn
 
@@ -589,6 +591,9 @@ func (c *Client) setDefaultHelo() error {
 
 // DialWithContext establishes a connection to the SMTP server with a given context.Context
 func (c *Client) DialWithContext(dialCtx context.Context) error {
+	c.mutex.Lock()
+	defer c.mutex.Unlock()
+
 	ctx, cancel := context.WithDeadline(dialCtx, time.Now().Add(c.connTimeout))
 	defer cancel()
 
@@ -602,17 +607,16 @@ func (c *Client) DialWithContext(dialCtx context.Context) error {
 			c.dialContextFunc = tlsDialer.DialContext
 		}
 	}
-	var err error
+	connection, err := c.dialContextFunc(ctx, "tcp", c.ServerAddr())
-	c.connection, err = c.dialContextFunc(ctx, "tcp", c.ServerAddr())
 	if err != nil && c.fallbackPort != 0 {
 		// TODO: should we somehow log or append the previous error?
-		c.connection, err = c.dialContextFunc(ctx, "tcp", c.serverFallbackAddr())
+		connection, err = c.dialContextFunc(ctx, "tcp", c.serverFallbackAddr())
 	}
 	if err != nil {
 		return err
 	}
 
-	client, err := smtp.NewClient(c.connection, c.host)
+	client, err := smtp.NewClient(connection, c.host)
 	if err != nil {
 		return err
 	}
@@ -691,7 +695,7 @@ func (c *Client) DialAndSendWithContext(ctx context.Context, messages ...*Msg) e
 // checkConn makes sure that a required server connection is available and extends the
 // connection deadline
 func (c *Client) checkConn() error {
-	if c.connection == nil {
+	if !c.smtpClient.HasConnection() {
 		return ErrNoActiveConnection
 	}
 
@@ -701,7 +705,7 @@ func (c *Client) checkConn() error {
 		}
 	}
 
-	if err := c.connection.SetDeadline(time.Now().Add(c.connTimeout)); err != nil {
+	if err := c.smtpClient.UpdateDeadline(c.connTimeout); err != nil {
 		return ErrDeadlineExtendFailed
 	}
 	return nil
@@ -715,7 +719,7 @@ func (c *Client) serverFallbackAddr() string {
 
 // tls tries to make sure that the STARTTLS requirements are satisfied
 func (c *Client) tls() error {
-	if c.connection == nil {
+	if !c.smtpClient.HasConnection() {
 		return ErrNoActiveConnection
 	}
 	if !c.useSSL && c.tlspolicy != NoTLS {

client_120.go

@@ -13,6 +13,8 @@ import (
 
 // Send sends out the mail message
 func (c *Client) Send(messages ...*Msg) (returnErr error) {
+	c.mutex.Lock()
+	defer c.mutex.Unlock()
 	if err := c.checkConn(); err != nil {
 		returnErr = &SendError{Reason: ErrConnCheck, errlist: []error{err}, isTemp: isTempError(err)}
 		return

connpool.go

@@ -1,215 +0,0 @@
-// SPDX-FileCopyrightText: 2022-2024 The go-mail Authors
-//
-// SPDX-License-Identifier: MIT
-
-package mail
-
-import (
-	"context"
-	"errors"
-	"fmt"
-	"net"
-	"sync"
-)
-
-// Parts of the connection pool code is forked/took inspiration from https://github.com/fatih/pool/
-// Thanks to Fatih Arslan and the project contributors for providing this great concurrency template.
-
-var (
-	// ErrClosed is returned when an operation is attempted on a closed connection pool.
-	ErrClosed = errors.New("connection pool is closed")
-	// ErrNilConn is returned when a nil connection is passed back to the connection pool.
-	ErrNilConn = errors.New("connection is nil")
-	// ErrPoolInvalidCap is returned when the connection pool's capacity settings are
-	// invalid (e.g., initial capacity is negative).
-	ErrPoolInvalidCap = errors.New("invalid connection pool capacity settings")
-)
-
-// Pool interface describes a connection pool implementation. A Pool is
-// thread-/go-routine safe.
-type Pool interface {
-	// Get returns a new connection from the pool. Closing the connections returns
-	// it back into the Pool. Closing a connection when the Pool is destroyed or
-	// full will be counted as an error.
-	Get(ctx context.Context) (net.Conn, error)
-
-	// Close closes the pool and all its connections. After Close() the pool is
-	// no longer usable.
-	Close()
-
-	// Size returns the current number of connections of the pool.
-	Size() int
-}
-
-// connPool implements the Pool interface
-type connPool struct {
-	// mutex is used to synchronize access to the connection pool to ensure thread-safe operations.
-	mutex sync.RWMutex
-	// conns is a channel used to manage and distribute net.Conn objects within the connection pool.
-	conns chan net.Conn
-
-	// dialCtxFunc represents the actual net.Conn returned by the DialContextFunc.
-	dialCtxFunc DialContextFunc
-	// dialNetwork specifies the network type (e.g., "tcp", "udp") used to establish connections in
-	// the connection pool.
-	dialNetwork string
-	// dialAddress specifies the address used to establish network connections within the connection pool.
-	dialAddress string
-}
-
-// PoolConn is a wrapper around net.Conn to modify the the behavior of net.Conn's Close() method.
-type PoolConn struct {
-	net.Conn
-	mutex    sync.RWMutex
-	pool     *connPool
-	unusable bool
-}
-
-// Close puts a given pool connection back to the pool instead of closing it.
-func (c *PoolConn) Close() error {
-	c.mutex.RLock()
-	defer c.mutex.RUnlock()
-
-	if c.unusable {
-		if c.Conn != nil {
-			return c.Conn.Close()
-		}
-		return nil
-	}
-	return c.pool.put(c.Conn)
-}
-
-// MarkUnusable marks the connection not usable any more, to let the pool close it instead
-// of returning it to pool.
-func (c *PoolConn) MarkUnusable() {
-	c.mutex.Lock()
-	c.unusable = true
-	c.mutex.Unlock()
-}
-
-// NewConnPool returns a new pool based on buffered channels with an initial
-// capacity and maximum capacity. The DialContextFunc is used when the initial
-// capacity is greater than zero to fill the pool. A zero initialCap doesn't
-// fill the Pool until a new Get() is called. During a Get(), if there is no
-// new connection available in the pool, a new connection will be created via
-// the corresponding DialContextFunc() method.
-func NewConnPool(ctx context.Context, initialCap, maxCap int, dialCtxFunc DialContextFunc,
-	network, address string,
-) (Pool, error) {
-	if initialCap < 0 || maxCap <= 0 || initialCap > maxCap {
-		return nil, ErrPoolInvalidCap
-	}
-
-	pool := &connPool{
-		conns:       make(chan net.Conn, maxCap),
-		dialCtxFunc: dialCtxFunc,
-		dialAddress: address,
-		dialNetwork: network,
-	}
-
-	// Initial connections for the pool. Pool will be closed on connection error
-	for i := 0; i < initialCap; i++ {
-		conn, err := dialCtxFunc(ctx, network, address)
-		if err != nil {
-			pool.Close()
-			return nil, fmt.Errorf("dialContextFunc is not able to fill the connection pool: %w", err)
-		}
-		pool.conns <- conn
-	}
-
-	return pool, nil
-}
-
-// Get satisfies the Get() method of the Pool inteface. If there is no new
-// connection available in the Pool, a new connection will be created via the
-// DialContextFunc() method.
-func (p *connPool) Get(ctx context.Context) (net.Conn, error) {
-	conns, dialCtxFunc := p.getConnsAndDialContext()
-	if conns == nil {
-		return nil, ErrClosed
-	}
-
-	// wrap the connections into the custom net.Conn implementation that puts
-	// connections back to the pool
-	select {
-	case <-ctx.Done():
-		return nil, fmt.Errorf("failed to get connection: %w", ctx.Err())
-	case conn := <-conns:
-		if conn == nil {
-			return nil, ErrClosed
-		}
-		return p.wrapConn(conn), nil
-	default:
-		conn, err := dialCtxFunc(ctx, p.dialNetwork, p.dialAddress)
-		if err != nil {
-			return nil, fmt.Errorf("dialContextFunc failed: %w", err)
-		}
-		return p.wrapConn(conn), nil
-	}
-}
-
-// Close terminates all connections in the pool and frees associated resources. Once closed,
-// the pool is no longer usable.
-func (p *connPool) Close() {
-	p.mutex.Lock()
-	conns := p.conns
-	p.conns = nil
-	p.dialCtxFunc = nil
-	p.dialAddress = ""
-	p.dialNetwork = ""
-	p.mutex.Unlock()
-
-	if conns == nil {
-		return
-	}
-
-	close(conns)
-	for conn := range conns {
-		_ = conn.Close()
-	}
-}
-
-// Size returns the current number of connections in the connection pool.
-func (p *connPool) Size() int {
-	conns, _ := p.getConnsAndDialContext()
-	return len(conns)
-}
-
-// getConnsAndDialContext returns the connection channel and the DialContext function for the
-// connection pool.
-func (p *connPool) getConnsAndDialContext() (chan net.Conn, DialContextFunc) {
-	p.mutex.RLock()
-	conns := p.conns
-	dialCtxFunc := p.dialCtxFunc
-	p.mutex.RUnlock()
-	return conns, dialCtxFunc
-}
-
-// put puts a passed connection back into the pool. If the pool is full or closed,
-// conn is simply closed. A nil conn will be rejected with an error.
-func (p *connPool) put(conn net.Conn) error {
-	if conn == nil {
-		return ErrNilConn
-	}
-
-	p.mutex.RLock()
-	defer p.mutex.RUnlock()
-
-	if p.conns == nil {
-		return conn.Close()
-	}
-
-	select {
-	case p.conns <- conn:
-		return nil
-	default:
-		return conn.Close()
-	}
-}
-
-// wrapConn wraps a given net.Conn with a PoolConn, modifying the net.Conn's Close() method.
-func (p *connPool) wrapConn(conn net.Conn) net.Conn {
-	poolconn := &PoolConn{pool: p}
-	poolconn.Conn = conn
-	return poolconn
-}

connpool_test.go

@@ -1,423 +0,0 @@
-// SPDX-FileCopyrightText: 2022-2024 The go-mail Authors
-//
-// SPDX-License-Identifier: MIT
-
-package mail
-
-import (
-	"context"
-	"fmt"
-	"net"
-	"sync"
-	"testing"
-	"time"
-)
-
-func TestNewConnPool(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	serverPort := TestServerPortBase + 10
-	featureSet := "250-AUTH PLAIN\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-	go func() {
-		if err := simpleSMTPServer(ctx, featureSet, true, serverPort); err != nil {
-			t.Errorf("failed to start test server: %s", err)
-			return
-		}
-	}()
-	time.Sleep(time.Millisecond * 300)
-
-	pool, err := newConnPool(serverPort)
-	if err != nil {
-		t.Errorf("failed to create connection pool: %s", err)
-	}
-	defer pool.Close()
-	if pool == nil {
-		t.Errorf("connection pool is nil")
-		return
-	}
-	if pool.Size() != 5 {
-		t.Errorf("expected 5 connections, got %d", pool.Size())
-	}
-	conn, err := pool.Get(context.Background())
-	if err != nil {
-		t.Errorf("failed to get connection: %s", err)
-	}
-	if _, err := conn.Write([]byte("EHLO test.localhost.localdomain\r\nQUIT\r\n")); err != nil {
-		t.Errorf("failed to write quit command to first connection: %s", err)
-	}
-}
-
-func TestConnPool_Get_Type(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	serverPort := TestServerPortBase + 11
-	featureSet := "250-AUTH PLAIN\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-	go func() {
-		if err := simpleSMTPServer(ctx, featureSet, true, serverPort); err != nil {
-			t.Errorf("failed to start test server: %s", err)
-			return
-		}
-	}()
-	time.Sleep(time.Millisecond * 300)
-
-	pool, err := newConnPool(serverPort)
-	if err != nil {
-		t.Errorf("failed to create connection pool: %s", err)
-	}
-	defer pool.Close()
-
-	conn, err := pool.Get(context.Background())
-	if err != nil {
-		t.Errorf("failed to get new connection from pool: %s", err)
-		return
-	}
-
-	_, ok := conn.(*PoolConn)
-	if !ok {
-		t.Error("received connection from pool is not of type PoolConn")
-		return
-	}
-	if _, err := conn.Write([]byte("EHLO test.localhost.localdomain\r\nQUIT\r\n")); err != nil {
-		t.Errorf("failed to write quit command to first connection: %s", err)
-	}
-}
-
-func TestConnPool_Get(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	serverPort := TestServerPortBase + 12
-	featureSet := "250-AUTH PLAIN\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-	go func() {
-		if err := simpleSMTPServer(ctx, featureSet, true, serverPort); err != nil {
-			t.Errorf("failed to start test server: %s", err)
-			return
-		}
-	}()
-	time.Sleep(time.Millisecond * 300)
-
-	p, _ := newConnPool(serverPort)
-	defer p.Close()
-
-	conn, err := p.Get(context.Background())
-	if err != nil {
-		t.Errorf("failed to get new connection from pool: %s", err)
-		return
-	}
-	if _, err = conn.Write([]byte("EHLO test.localhost.localdomain\r\nQUIT\r\n")); err != nil {
-		t.Errorf("failed to write quit command to first connection: %s", err)
-	}
-
-	if p.Size() != 4 {
-		t.Errorf("getting new connection from pool failed. Expected pool size: 4, got %d", p.Size())
-	}
-
-	var wg sync.WaitGroup
-	for i := 0; i < 4; i++ {
-		wg.Add(1)
-		go func() {
-			defer wg.Done()
-			wgconn, err := p.Get(context.Background())
-			if err != nil {
-				t.Errorf("failed to get new connection from pool: %s", err)
-			}
-			if _, err = wgconn.Write([]byte("EHLO test.localhost.localdomain\r\nQUIT\r\n")); err != nil {
-				t.Errorf("failed to write quit command to first connection: %s", err)
-			}
-		}()
-	}
-	wg.Wait()
-
-	if p.Size() != 0 {
-		t.Errorf("Get error. Expecting 0, got %d", p.Size())
-	}
-
-	conn, err = p.Get(context.Background())
-	if err != nil {
-		t.Errorf("failed to get new connection from pool: %s", err)
-	}
-	if _, err = conn.Write([]byte("EHLO test.localhost.localdomain\r\nQUIT\r\n")); err != nil {
-		t.Errorf("failed to write quit command to first connection: %s", err)
-	}
-	p.Close()
-}
-
-func TestPoolConn_Close(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	serverPort := TestServerPortBase + 13
-	featureSet := "250-AUTH PLAIN\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-	go func() {
-		if err := simpleSMTPServer(ctx, featureSet, true, serverPort); err != nil {
-			t.Errorf("failed to start test server: %s", err)
-			return
-		}
-	}()
-	time.Sleep(time.Millisecond * 300)
-
-	netDialer := net.Dialer{}
-	p, err := NewConnPool(context.Background(), 0, 30, netDialer.DialContext, "tcp",
-		fmt.Sprintf("127.0.0.1:%d", serverPort))
-	if err != nil {
-		t.Errorf("failed to create connection pool: %s", err)
-	}
-	defer p.Close()
-
-	conns := make([]net.Conn, 30)
-	for i := 0; i < 30; i++ {
-		conn, _ := p.Get(context.Background())
-		if _, err = conn.Write([]byte("EHLO test.localhost.localdomain\r\nQUIT\r\n")); err != nil {
-			t.Errorf("failed to write quit command to first connection: %s", err)
-		}
-		conns[i] = conn
-	}
-	for _, conn := range conns {
-		if err = conn.Close(); err != nil {
-			t.Errorf("failed to close connection: %s", err)
-		}
-	}
-
-	if p.Size() != 30 {
-		t.Errorf("failed to return all connections to pool. Expected pool size: 30, got %d", p.Size())
-	}
-
-	conn, err := p.Get(context.Background())
-	if err != nil {
-		t.Errorf("failed to get new connection from pool: %s", err)
-	}
-	if _, err = conn.Write([]byte("EHLO test.localhost.localdomain\r\nQUIT\r\n")); err != nil {
-		t.Errorf("failed to write quit command to first connection: %s", err)
-	}
-	p.Close()
-
-	if err = conn.Close(); err != nil {
-		t.Errorf("failed to close connection: %s", err)
-	}
-	if p.Size() != 0 {
-		t.Errorf("closed pool shouldn't allow to put connections.")
-	}
-}
-
-func TestPoolConn_MarkUnusable(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	serverPort := TestServerPortBase + 14
-	featureSet := "250-AUTH PLAIN\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-	go func() {
-		if err := simpleSMTPServer(ctx, featureSet, true, serverPort); err != nil {
-			t.Errorf("failed to start test server: %s", err)
-			return
-		}
-	}()
-	time.Sleep(time.Millisecond * 300)
-
-	pool, _ := newConnPool(serverPort)
-	defer pool.Close()
-
-	conn, err := pool.Get(context.Background())
-	if err != nil {
-		t.Errorf("failed to get new connection from pool: %s", err)
-	}
-	if err = conn.Close(); err != nil {
-		t.Errorf("failed to close connection: %s", err)
-	}
-
-	poolSize := pool.Size()
-	conn, err = pool.Get(context.Background())
-	if err != nil {
-		t.Errorf("failed to get new connection from pool: %s", err)
-	}
-	if err = conn.Close(); err != nil {
-		t.Errorf("failed to close connection: %s", err)
-	}
-	if pool.Size() != poolSize {
-		t.Errorf("pool size is expected to be equal to initial size")
-	}
-
-	conn, err = pool.Get(context.Background())
-	if err != nil {
-		t.Errorf("failed to get new connection from pool: %s", err)
-	}
-	if pc, ok := conn.(*PoolConn); !ok {
-		t.Errorf("this should never happen")
-	} else {
-		pc.MarkUnusable()
-	}
-	if err = conn.Close(); err != nil {
-		t.Errorf("failed to close connection: %s", err)
-	}
-	if pool.Size() != poolSize-1 {
-		t.Errorf("pool size is expected to be: %d but got: %d", poolSize-1, pool.Size())
-	}
-}
-
-func TestConnPool_Close(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	serverPort := TestServerPortBase + 15
-	featureSet := "250-AUTH PLAIN\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-	go func() {
-		if err := simpleSMTPServer(ctx, featureSet, true, serverPort); err != nil {
-			t.Errorf("failed to start test server: %s", err)
-			return
-		}
-	}()
-	time.Sleep(time.Millisecond * 300)
-
-	pool, err := newConnPool(serverPort)
-	if err != nil {
-		t.Errorf("failed to create connection pool: %s", err)
-	}
-	pool.Close()
-
-	castPool := pool.(*connPool)
-
-	if castPool.conns != nil {
-		t.Error("closing pool failed: conns channel should be nil")
-	}
-	if castPool.dialCtxFunc != nil {
-		t.Error("closing pool failed: dialCtxFunc should be nil")
-	}
-	if castPool.dialAddress != "" {
-		t.Error("closing pool failed: dialAddress should be empty")
-	}
-	if castPool.dialNetwork != "" {
-		t.Error("closing pool failed: dialNetwork should be empty")
-	}
-
-	conn, err := pool.Get(context.Background())
-	if err == nil {
-		t.Errorf("closing pool failed: getting new connection should return an error")
-	}
-	if conn != nil {
-		t.Errorf("closing pool failed: getting new connection should return a nil-connection")
-	}
-	if pool.Size() != 0 {
-		t.Errorf("closing pool failed: pool size should be 0, but got: %d", pool.Size())
-	}
-}
-
-func TestConnPool_Concurrency(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	serverPort := TestServerPortBase + 16
-	featureSet := "250-AUTH PLAIN\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-	go func() {
-		if err := simpleSMTPServer(ctx, featureSet, true, serverPort); err != nil {
-			t.Errorf("failed to start test server: %s", err)
-			return
-		}
-	}()
-	time.Sleep(time.Millisecond * 300)
-
-	pool, err := newConnPool(serverPort)
-	if err != nil {
-		t.Errorf("failed to create connection pool: %s", err)
-	}
-	defer pool.Close()
-	pipe := make(chan net.Conn)
-
-	getWg := sync.WaitGroup{}
-	closeWg := sync.WaitGroup{}
-	for i := 0; i < 30; i++ {
-		getWg.Add(1)
-		closeWg.Add(1)
-		go func() {
-			conn, err := pool.Get(context.Background())
-			if err != nil {
-				t.Errorf("failed to get new connection from pool: %s", err)
-			}
-			pipe <- conn
-			getWg.Done()
-		}()
-
-		go func() {
-			conn := <-pipe
-			if conn == nil {
-				return
-			}
-			if err = conn.Close(); err != nil {
-				t.Errorf("failed to close connection: %s", err)
-			}
-			closeWg.Done()
-		}()
-		getWg.Wait()
-		closeWg.Wait()
-	}
-}
-
-func TestConnPool_GetContextCancel(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	serverPort := TestServerPortBase + 17
-	featureSet := "250-AUTH PLAIN\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-	go func() {
-		if err := simpleSMTPServer(ctx, featureSet, true, serverPort); err != nil {
-			t.Errorf("failed to start test server: %s", err)
-			return
-		}
-	}()
-	time.Sleep(time.Millisecond * 300)
-
-	p, err := newConnPool(serverPort)
-	if err != nil {
-		t.Errorf("failed to create connection pool: %s", err)
-	}
-	defer p.Close()
-
-	connCtx, connCancel := context.WithCancel(context.Background())
-	defer connCancel()
-
-	conn, err := p.Get(connCtx)
-	if err != nil {
-		t.Errorf("failed to get new connection from pool: %s", err)
-		return
-	}
-	if _, err = conn.Write([]byte("EHLO test.localhost.localdomain\r\nQUIT\r\n")); err != nil {
-		t.Errorf("failed to write quit command to first connection: %s", err)
-	}
-
-	if p.Size() != 4 {
-		t.Errorf("getting new connection from pool failed. Expected pool size: 4, got %d", p.Size())
-	}
-
-	var wg sync.WaitGroup
-	for i := 0; i < 4; i++ {
-		wg.Add(1)
-		go func() {
-			defer wg.Done()
-			wgconn, err := p.Get(connCtx)
-			if err != nil {
-				t.Errorf("failed to get new connection from pool: %s", err)
-			}
-			if _, err = wgconn.Write([]byte("EHLO test.localhost.localdomain\r\nQUIT\r\n")); err != nil {
-				t.Errorf("failed to write quit command to first connection: %s", err)
-			}
-		}()
-	}
-	wg.Wait()
-
-	if p.Size() != 0 {
-		t.Errorf("Get error. Expecting 0, got %d", p.Size())
-	}
-
-	connCancel()
-	_, err = p.Get(connCtx)
-	if err == nil {
-		t.Errorf("getting new connection on canceled context should fail, but didn't")
-	}
-	p.Close()
-}
-
-func newConnPool(port int) (Pool, error) {
-	netDialer := net.Dialer{}
-	return NewConnPool(context.Background(), 5, 30, netDialer.DialContext, "tcp",
-		fmt.Sprintf("127.0.0.1:%d", port))
-}

smtp/smtp.go

@@ -30,6 +30,7 @@ import (
 	"net/textproto"
 	"os"
 	"strings"
+	"time"
 
 	"github.com/wneessen/go-mail/log"
 )
@@ -472,6 +473,19 @@ func (c *Client) SetDSNRcptNotifyOption(d string) {
 	c.dsnrntype = d
 }
 
+// HasConnection checks if the client has an active connection.
+// Returns true if the `conn` field is not nil, indicating an active connection.
+func (c *Client) HasConnection() bool {
+	return c.conn != nil
+}
+
+func (c *Client) UpdateDeadline(timeout time.Duration) error {
+	if err := c.conn.SetDeadline(time.Now().Add(timeout)); err != nil {
+		return fmt.Errorf("smtp: failed to update deadline: %w", err)
+	}
+	return nil
+}
+
 // debugLog checks if the debug flag is set and if so logs the provided message to
 // the log.Logger interface
 func (c *Client) debugLog(d log.Direction, f string, a ...interface{}) {