zero-knowledge file sharing
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TypeScript
12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879808182838485868788899091929394959697import { Database } from "bun:sqlite";import { mkdirSync, unlinkSync } from "fs";
import { config } from "./config.ts";
const DATA_DIR = config.dataDir;const FILES_DIR = `${DATA_DIR}/files`;mkdirSync(FILES_DIR, { recursive: true });
const db = new Database(`${DATA_DIR}/drop.db`, { create: true });db.run("PRAGMA journal_mode = WAL;");
db.run(` CREATE TABLE IF NOT EXISTS files ( id TEXT PRIMARY KEY, expires_at INTEGER NOT NULL, burn_after_read INTEGER NOT NULL, meta_enc TEXT NOT NULL );`);
db.run( "CREATE INDEX IF NOT EXISTS idx_files_expires_at ON files (expires_at);",);
const insertStmt = db.prepare<void, [string, number, number, string]>( "INSERT INTO files (id, expires_at, burn_after_read, meta_enc) VALUES (?, ?, ?, ?)",);
type FileRow = { id: string; expires_at: number; burn_after_read: number; meta_enc: string;};
const selectStmt = db.prepare<FileRow, [string]>( "SELECT * FROM files WHERE id = ?",);
const deleteStmt = db.prepare<void, [string]>("DELETE FROM files WHERE id = ?");
const burnStmt = db.prepare<FileRow, [string]>( "DELETE FROM files WHERE id = ? AND burn_after_read = 1 RETURNING *",);
const cleanStmt = db.prepare<{ id: string }, [number]>( "DELETE FROM files WHERE expires_at <= ? RETURNING id",);
export function createFile( id: string, expiresAt: number, burnAfterRead: boolean, metaEnc: string,): void { insertStmt.run(id, expiresAt, burnAfterRead ? 1 : 0, metaEnc);}
// Read-only lookup — does not trigger burn-after-read or delete expired rowsexport function peekFile(id: string) { const row = selectStmt.get(id); if (!row) return null; if (row.expires_at <= Math.floor(Date.now() / 1000)) return null; return row;}
export function getFile(id: string) { // Try atomic burn-after-read first — if the row has burn_after_read=1, // this deletes and returns it in one step, preventing double-reads const burned = burnStmt.get(id); if (burned) { if (burned.expires_at <= Math.floor(Date.now() / 1000)) return null; return burned; } const row = selectStmt.get(id); if (!row) return null; if (row.expires_at <= Math.floor(Date.now() / 1000)) { deleteStmt.run(id); return null; } return row;}
export function unlinkFile(id: string): void { try { unlinkSync(`${FILES_DIR}/${id}`); } catch {}}
export function cleanExpired(): void { const now = Math.floor(Date.now() / 1000); for (const { id } of cleanStmt.all(now)) { unlinkFile(id); }}