fix connection limits

an SFTP client can start multiple transfers on a single connection

Signed-off-by: Nicola Murino <nicola.murino@gmail.com>

internal/ftpd/ftpd_test.go

@@ -37,6 +37,7 @@ import (
 
 	ftpserver "github.com/fclairamb/ftpserverlib"
 	"github.com/jlaffaye/ftp"
+	"github.com/pkg/sftp"
 	"github.com/pquerna/otp"
 	"github.com/pquerna/otp/totp"
 	"github.com/rs/zerolog"
@@ -44,6 +45,7 @@ import (
 	sdkkms "github.com/sftpgo/sdk/kms"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"golang.org/x/crypto/ssh"
 
 	"github.com/drakkan/sftpgo/v2/internal/common"
 	"github.com/drakkan/sftpgo/v2/internal/config"
@@ -671,6 +673,7 @@ func TestBasicFTPHandling(t *testing.T) {
 	assert.Eventually(t, func() bool { return len(common.Connections.GetStats("")) == 0 }, 1*time.Second, 50*time.Millisecond)
 	assert.Eventually(t, func() bool { return common.Connections.GetClientConnections() == 0 }, 1000*time.Millisecond,
 		50*time.Millisecond)
+	assert.Equal(t, int32(0), common.Connections.GetTotalTransfers())
 }
 
 func TestHTTPFs(t *testing.T) {
@@ -715,6 +718,7 @@ func TestHTTPFs(t *testing.T) {
 	assert.Eventually(t, func() bool { return len(common.Connections.GetStats("")) == 0 }, 1*time.Second, 50*time.Millisecond)
 	assert.Eventually(t, func() bool { return common.Connections.GetClientConnections() == 0 }, 1000*time.Millisecond,
 		50*time.Millisecond)
+	assert.Equal(t, int32(0), common.Connections.GetTotalTransfers())
 }
 
 func TestListDirWithWildcards(t *testing.T) {
@@ -1735,6 +1739,66 @@ func TestMaxPerHostConnections(t *testing.T) {
 	common.Config.MaxPerHostConnections = oldValue
 }
 
+func TestMaxTransfers(t *testing.T) {
+	oldValue := common.Config.MaxPerHostConnections
+	common.Config.MaxPerHostConnections = 2
+
+	assert.Eventually(t, func() bool {
+		return common.Connections.GetClientConnections() == 0
+	}, 1000*time.Millisecond, 50*time.Millisecond)
+
+	user := getTestUser()
+	err := dataprovider.AddUser(&user, "", "", "")
+	assert.NoError(t, err)
+	user.Password = ""
+
+	testFilePath := filepath.Join(homeBasePath, testFileName)
+	testFileSize := int64(65535)
+	err = createTestFile(testFilePath, testFileSize)
+	assert.NoError(t, err)
+
+	conn, sftpClient, err := getSftpClient(user)
+	assert.NoError(t, err)
+	defer conn.Close()
+	defer sftpClient.Close()
+
+	f1, err := sftpClient.Create("file1")
+	assert.NoError(t, err)
+	f2, err := sftpClient.Create("file2")
+	assert.NoError(t, err)
+	_, err = f1.Write([]byte(" "))
+	assert.NoError(t, err)
+	_, err = f2.Write([]byte(" "))
+	assert.NoError(t, err)
+
+	client, err := getFTPClient(user, true, nil)
+	if assert.NoError(t, err) {
+		err = checkBasicFTP(client)
+		assert.NoError(t, err)
+		err = ftpUploadFile(testFilePath, testFileName, testFileSize, client, 0)
+		assert.Error(t, err)
+		localDownloadPath := filepath.Join(homeBasePath, testDLFileName)
+		err = ftpDownloadFile(testFileName, localDownloadPath, testFileSize, client, 0)
+		assert.Error(t, err)
+		err := client.Quit()
+		assert.NoError(t, err)
+		err = os.Remove(localDownloadPath)
+		assert.NoError(t, err)
+	}
+
+	err = f1.Close()
+	assert.NoError(t, err)
+	err = f2.Close()
+	assert.NoError(t, err)
+
+	err = dataprovider.DeleteUser(user.Username, "", "", "")
+	assert.NoError(t, err)
+	err = os.RemoveAll(user.GetHomeDir())
+	assert.NoError(t, err)
+
+	common.Config.MaxPerHostConnections = oldValue
+}
+
 func TestRateLimiter(t *testing.T) {
 	oldConfig := config.GetCommonConfig()
 
@@ -3962,6 +4026,7 @@ func TestNestedVirtualFolders(t *testing.T) {
 	assert.Eventually(t, func() bool { return len(common.Connections.GetStats("")) == 0 }, 1*time.Second, 50*time.Millisecond)
 	assert.Eventually(t, func() bool { return common.Connections.GetClientConnections() == 0 }, 1000*time.Millisecond,
 		50*time.Millisecond)
+	assert.Equal(t, int32(0), common.Connections.GetTotalTransfers())
 }
 
 func checkBasicFTP(client *ftp.ServerConn) error {
@@ -4213,6 +4278,30 @@ func getPreLoginScriptContent(user dataprovider.User, nonJSONResponse bool) []by
 	return content
 }
 
+func getSftpClient(user dataprovider.User) (*ssh.Client, *sftp.Client, error) {
+	var sftpClient *sftp.Client
+	config := &ssh.ClientConfig{
+		User:            user.Username,
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
+		Timeout:         5 * time.Second,
+	}
+	if user.Password != "" {
+		config.Auth = []ssh.AuthMethod{ssh.Password(user.Password)}
+	} else {
+		config.Auth = []ssh.AuthMethod{ssh.Password(defaultPassword)}
+	}
+
+	conn, err := ssh.Dial("tcp", sftpServerAddr, config)
+	if err != nil {
+		return conn, sftpClient, err
+	}
+	sftpClient, err = sftp.NewClient(conn)
+	if err != nil {
+		conn.Close()
+	}
+	return conn, sftpClient, err
+}
+
 func getExitCodeScriptContent(exitCode int) []byte {
 	content := []byte("#!/bin/sh\n\n")
 	content = append(content, []byte(fmt.Sprintf("exit %v", exitCode))...)