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Fix command injection via file path in convertToWavType #259

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Fix command injection via file path in convertToWavType #259

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50 changes: 39 additions & 11 deletions src/utils.ts
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
import { execFileSync } from 'child_process'
import fs from 'fs'
import path from 'path'
import shell from 'shelljs'
import { Logger } from './types'

export const checkIfFileExists = (filePath: string) => {
Expand Down Expand Up @@ -39,6 +39,42 @@ async function isValidWavHeader(filePath: string): Promise<boolean> {
})
}

// Run ffmpeg to convert `inputFilePath` to a 16 kHz mono PCM WAV at `outputFilePath`.
// Arguments are passed as a discrete argv array with NO shell, so a path containing
// shell metacharacters (quotes, `;`, `$()`, backticks) is treated strictly as data and
// can never be interpreted as a command. Throws with the original error message on failure.
function runFfmpegConversion(inputFilePath: string, outputFilePath: string): void {
try {
execFileSync(
'ffmpeg',
[
'-nostats',
'-loglevel',
'error',
'-y',
'-i',
inputFilePath,
'-ar',
'16000',
'-ac',
'1',
'-c:a',
'pcm_s16le',
outputFilePath,
],
{ stdio: 'pipe' }
)
} catch (err) {
const stderr =
err && typeof err === 'object' && 'stderr' in err && (err as { stderr?: unknown }).stderr
? String((err as { stderr: unknown }).stderr)
: err instanceof Error
? err.message
: 'unknown error'
throw new Error(`[Nodejs-whisper] Failed to convert audio file: ${stderr}`)
}
}

export const convertToWavType = async (inputFilePath: string, logger: Logger = console) => {
const fileExtension = path.extname(inputFilePath).toLowerCase()

Expand All @@ -55,11 +91,7 @@ export const convertToWavType = async (inputFilePath: string, logger: Logger = c

// Use a temporary file to avoid overwrite conflicts
const tempFile = inputFilePath + '.temp.wav'
const command = `ffmpeg -nostats -loglevel error -y -i "${inputFilePath}" -ar 16000 -ac 1 -c:a pcm_s16le "${tempFile}"`
const result = shell.exec(command)
if (result.code !== 0) {
throw new Error(`[Nodejs-whisper] Failed to convert audio file: ${result.stderr}`)
}
runFfmpegConversion(inputFilePath, tempFile)

fs.renameSync(tempFile, inputFilePath)
return inputFilePath
Expand All @@ -73,11 +105,7 @@ export const convertToWavType = async (inputFilePath: string, logger: Logger = c

logger.debug(`[Nodejs-whisper] Converting to a new WAV file: ${outputFilePath}`)

const command = `ffmpeg -nostats -loglevel error -y -i "${inputFilePath}" -ar 16000 -ac 1 -c:a pcm_s16le "${outputFilePath}"`
const result = shell.exec(command)
if (result.code !== 0) {
throw new Error(`[Nodejs-whisper] Failed to convert audio file: ${result.stderr}`)
}
runFfmpegConversion(inputFilePath, outputFilePath)
return outputFilePath
}
}
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