From 5cebe53fa15ef110846e629c73822b7b2887935c Mon Sep 17 00:00:00 2001
From: MickaelK <mickael@kerjean.me>
Date: Wed, 13 May 2026 12:24:33 +1000
Subject: [PATCH] feature (plg_backend_sftp): instrument sftp client

---
 server/plugin/plg_backend_sftp/index.go   |  5 +-
 server/plugin/plg_backend_sftp/tracing.go | 87 +++++++++++++++++++++++
 2 files changed, 90 insertions(+), 2 deletions(-)
 create mode 100644 server/plugin/plg_backend_sftp/tracing.go

diff --git a/server/plugin/plg_backend_sftp/index.go b/server/plugin/plg_backend_sftp/index.go
index 5e364588..b24089a7 100644
--- a/server/plugin/plg_backend_sftp/index.go
+++ b/server/plugin/plg_backend_sftp/index.go
@@ -17,7 +17,7 @@ var SftpCache AppCache
 
 type Sftp struct {
 	SSHClient  *ssh.Client
-	SFTPClient *sftp.Client
+	SFTPClient *tracedClient
 	wg         *sync.WaitGroup
 }
 
@@ -74,6 +74,7 @@ func (s Sftp) Init(params map[string]string, app *App) (IBackend, error) {
 			<-app.Context.Done()
 			d.wg.Done()
 		}()
+		d.SFTPClient.app = app
 		return d, nil
 	}
 
@@ -184,7 +185,7 @@ func (s Sftp) Init(params map[string]string, app *App) (IBackend, error) {
 	if err != nil {
 		return &s, err
 	}
-	s.SFTPClient = session
+	s.SFTPClient = &tracedClient{Client: session, app: app}
 	s.wg = new(sync.WaitGroup)
 	s.wg.Add(1)
 	go func() {
diff --git a/server/plugin/plg_backend_sftp/tracing.go b/server/plugin/plg_backend_sftp/tracing.go
new file mode 100644
index 00000000..1d0017eb
--- /dev/null
+++ b/server/plugin/plg_backend_sftp/tracing.go
@@ -0,0 +1,87 @@
+package plg_backend_sftp
+
+import (
+	"os"
+
+	. "github.com/mickael-kerjean/filestash/server/common"
+	"github.com/mickael-kerjean/filestash/server/pkg/tracer"
+
+	"github.com/pkg/sftp"
+)
+
+type tracedClient struct {
+	*sftp.Client
+	app *App
+}
+
+func (t *tracedClient) ReadDir(path string) ([]os.FileInfo, error) {
+	span := NewSpan(t.app, "ReadDir", map[string]string{"sftp.path": path, "sftp.packet": "SSH_FXP_READDIR"})
+	defer span.Close()
+	files, err := t.Client.ReadDir(path)
+	span.SetError(err)
+	return files, err
+}
+
+func (t *tracedClient) OpenFile(path string, flags int) (*sftp.File, error) {
+	span := NewSpan(t.app, "OpenFile", map[string]string{"sftp.path": path, "sftp.packet": "SSH_FXP_OPEN"})
+	defer span.Close()
+	f, err := t.Client.OpenFile(path, flags)
+	span.SetError(err)
+	return f, err
+}
+
+func (t *tracedClient) Mkdir(path string) error {
+	span := NewSpan(t.app, "Mkdir", map[string]string{"sftp.path": path, "sftp.packet": "SSH_FXP_MKDIR"})
+	defer span.Close()
+	err := t.Client.Mkdir(path)
+	span.SetError(err)
+	return err
+}
+
+func (t *tracedClient) Remove(path string) error {
+	span := NewSpan(t.app, "Remove", map[string]string{"sftp.path": path, "sftp.packet": "SSH_FXP_REMOVE"})
+	defer span.Close()
+	err := t.Client.Remove(path)
+	span.SetError(err)
+	return err
+}
+
+func (t *tracedClient) RemoveDirectory(path string) error {
+	span := NewSpan(t.app, "RemoveDirectory", map[string]string{"sftp.path": path, "sftp.packet": "SSH_FXP_RMDIR"})
+	defer span.Close()
+	err := t.Client.RemoveDirectory(path)
+	span.SetError(err)
+	return err
+}
+
+func (t *tracedClient) Rename(from, to string) error {
+	span := NewSpan(t.app, "Rename", map[string]string{"sftp.from": from, "sftp.to": to, "sftp.packet": "SSH_FXP_RENAME"})
+	defer span.Close()
+	err := t.Client.Rename(from, to)
+	span.SetError(err)
+	return err
+}
+
+func (t *tracedClient) Stat(path string) (os.FileInfo, error) {
+	span := NewSpan(t.app, "Stat", map[string]string{"sftp.path": path, "sftp.packet": "SSH_FXP_STAT"})
+	defer span.Close()
+	f, err := t.Client.Stat(path)
+	span.SetError(err)
+	return f, err
+}
+
+func (t *tracedClient) Getwd() (string, error) {
+	span := NewSpan(t.app, "Getwd", map[string]string{"sftp.packet": "SSH_FXP_REALPATH"})
+	defer span.Close()
+	cwd, err := t.Client.Getwd()
+	span.SetError(err)
+	return cwd, err
+}
+
+func NewSpan(app *App, name string, attrs map[string]string) tracer.ISpan {
+	return tracer.StartSpan(tracer.TraceFromContext(app.Context), name, tracer.SpanOptions{
+		Kind:       tracer.KindClient,
+		Service:    "sftp",
+		Attributes: attrs,
+	})
+}