feat(file-explorer): support drag-and-drop file import over SSH (#1279)

Co-authored-by: Orca <help@stably.ai>

src/main/ssh/sftp-upload.ts

@@ -0,0 +1,97 @@
+import { createReadStream } from 'fs'
+import { readdir } from 'fs/promises'
+import { join as pathJoin } from 'path'
+import type { SFTPWrapper } from 'ssh2'
+
+export function mkdirSftp(sftp: SFTPWrapper, path: string): Promise<void> {
+  return new Promise((resolve, reject) => {
+    sftp.mkdir(path, (err) => {
+      // Why: SFTP status code 4 (SSH_FX_FAILURE) is a generic code that
+      // OpenSSH returns for "already exists," but could also cover other
+      // failures (e.g. permission denied on parent). We accept this ambiguity
+      // because the next operation (write/recurse) will surface the real error.
+      if (err && (err as { code?: number }).code !== 4) {
+        reject(err)
+      } else {
+        resolve()
+      }
+    })
+  })
+}
+
+export function uploadFile(
+  sftp: SFTPWrapper,
+  localPath: string,
+  remotePath: string
+): Promise<void> {
+  return new Promise((resolve, reject) => {
+    let settled = false
+    const readStream = createReadStream(localPath)
+    const writeStream = sftp.createWriteStream(remotePath)
+
+    const settle = (fn: typeof resolve | typeof reject, val?: unknown): void => {
+      if (settled) {
+        return
+      }
+      settled = true
+      readStream.destroy()
+      writeStream.destroy()
+      fn(val as never)
+    }
+
+    writeStream.on('close', () => settle(resolve))
+    writeStream.on('error', (err) => settle(reject, err))
+    readStream.on('error', (err) => settle(reject, err))
+
+    readStream.pipe(writeStream)
+  })
+}
+
+export async function uploadDirectory(
+  sftp: SFTPWrapper,
+  localDir: string,
+  remoteDir: string
+): Promise<void> {
+  const entries = await readdir(localDir, { withFileTypes: true })
+  for (const entry of entries) {
+    const localPath = pathJoin(localDir, entry.name)
+    const remotePath = `${remoteDir}/${entry.name}`
+
+    // Why: skip symlinks and special files (sockets, FIFOs, devices) to
+    // prevent following symlinks that could exfiltrate local files to the
+    // remote. The caller's pre-scan catches symlinks up-front, but this
+    // guard closes the TOCTOU gap if one is created between scan and upload.
+    if (entry.isSymbolicLink() || (!entry.isFile() && !entry.isDirectory())) {
+      continue
+    }
+
+    if (entry.isDirectory()) {
+      await mkdirSftp(sftp, remotePath)
+      await uploadDirectory(sftp, localPath, remotePath)
+    } else {
+      await uploadFile(sftp, localPath, remotePath)
+    }
+  }
+}
+
+/**
+ * Check whether a path exists on the remote via SFTP lstat.
+ * Returns true if the path exists (file, directory, or symlink).
+ */
+export function sftpPathExists(sftp: SFTPWrapper, remotePath: string): Promise<boolean> {
+  return new Promise((resolve, reject) => {
+    sftp.lstat(remotePath, (err) => {
+      if (!err) {
+        resolve(true)
+        return
+      }
+      // Why: SFTP status code 2 = SSH_FX_NO_SUCH_FILE — the path does not
+      // exist, which is the expected "no collision" signal for deconfliction.
+      if ((err as { code?: number }).code === 2) {
+        resolve(false)
+        return
+      }
+      reject(err)
+    })
+  })
+}

src/main/ssh/ssh-relay-deploy-helpers.ts

@@ -1,63 +1,9 @@
-import { createReadStream } from 'fs'
-import type { SFTPWrapper, ClientChannel } from 'ssh2'
+import type { ClientChannel } from 'ssh2'
 import type { SshConnection } from './ssh-connection'
 import { RELAY_SENTINEL, RELAY_SENTINEL_TIMEOUT_MS } from './relay-protocol'
 import type { MultiplexerTransport } from './ssh-channel-multiplexer'
 
-// ── SFTP upload helpers ───────────────────────────────────────────────
-
-export async function uploadDirectory(
-  sftp: SFTPWrapper,
-  localDir: string,
-  remoteDir: string
-): Promise<void> {
-  const { readdirSync, statSync } = await import('fs')
-  const { join: pathJoin } = await import('path')
-
-  const entries = readdirSync(localDir)
-  for (const entry of entries) {
-    const localPath = pathJoin(localDir, entry)
-    const remotePath = `${remoteDir}/${entry}`
-    const stat = statSync(localPath)
-
-    if (stat.isDirectory()) {
-      await mkdirSftp(sftp, remotePath)
-      await uploadDirectory(sftp, localPath, remotePath)
-    } else {
-      await uploadFile(sftp, localPath, remotePath)
-    }
-  }
-}
-
-export function mkdirSftp(sftp: SFTPWrapper, path: string): Promise<void> {
-  return new Promise((resolve, reject) => {
-    sftp.mkdir(path, (err) => {
-      // Ignore "already exists" errors (SFTP status code 4 = SSH_FX_FAILURE)
-      if (err && (err as { code?: number }).code !== 4) {
-        reject(err)
-      } else {
-        resolve()
-      }
-    })
-  })
-}
-
-export function uploadFile(
-  sftp: SFTPWrapper,
-  localPath: string,
-  remotePath: string
-): Promise<void> {
-  return new Promise((resolve, reject) => {
-    const readStream = createReadStream(localPath)
-    const writeStream = sftp.createWriteStream(remotePath)
-
-    writeStream.on('close', resolve)
-    writeStream.on('error', reject)
-    readStream.on('error', reject)
-
-    readStream.pipe(writeStream)
-  })
-}
+export { uploadFile, uploadDirectory, mkdirSftp } from './sftp-upload'
 
 // ── Sentinel detection ────────────────────────────────────────────────