OverviewFilesCommitsIssuesDocsReleasesPeers

pear-git / bin / git-remote-punch

275 lines · text ref:
#!/usr/bin/env bare
/**
 * git-remote-punch - Git remote helper for punch:// URLs
 *
 * Primary P2P git transport for pear-git.
 *
 * Usage:
 *   git clone punch://serverkey/repo
 *   git clone punch://petname/repo (if petname configured)
 *   git clone punch://serverkey/repo?https=https://fallback.url/repo.git
 *
 * Git passes two arguments:
 *   $1 = remote name (usually "origin" or the URL itself)
 *   $2 = remote URL (punch://...)
 *
 * Protocol:
 * 1. Parse punch:// URL to get server key and repo name
 * 2. Derive topic: hash(serverKey + repoName)
 * 3. Connect to topic via Hyperswarm (P2P)
 * 4. If P2P fails, fall back to HTTPS URL if provided
 * 5. Proxy stdin/stdout to connection
 */

// Load Node.js compatibility for Bare runtime
await import('bare-node-runtime/global')

import { spawn } from 'bare-subprocess'
import fs from 'bare-fs'
import path from 'bare-path'
import os from 'bare-os'
import { PetnameManager } from '../lib/p2p/discovery/petnames.js'
import { TopicConnector } from '../lib/p2p/discovery/topic-manager.js'
import { GitP2PClient } from '../lib/p2p/protocol/git-p2p-handler.js'

// Load config for default gateway
function loadConfig() {
  try {
    const configPath = path.join(os.homedir(), '.config', 'pear-git', 'config.json')
    const data = fs.readFileSync(configPath, 'utf-8')
    return JSON.parse(data)
  } catch {
    return {}
  }
}

const args = process.argv.slice(2)
const remoteName = args[0]
const remoteUrl = args[1] || remoteName

async function main() {
  const config = loadConfig()
  const petnames = new PetnameManager()
  await petnames.init()

  let parsed
  let httpsUrl = null

  try {
    const urlObj = new URL(remoteUrl)
    httpsUrl = urlObj.searchParams.get('https')

    // Remove query params for petname parsing
    const cleanUrl = `${urlObj.protocol}//${urlObj.host}${urlObj.pathname}`
    parsed = petnames.parseUrl(cleanUrl)

    if (!httpsUrl && config.defaultGateway) {
      httpsUrl = `${config.defaultGateway}/${parsed.repo}.git`
    }
  } catch (err) {
    console.error(`error: ${err.message}`)
    process.exit(128)
  }

  const { key, repo, isPetname, petname } = parsed

  if (isPetname) {
    console.error(`[punch] Resolved ${petname} -> ${key.slice(0, 8)}...`)
  }
  if (httpsUrl) {
    console.error(`[punch] HTTPS fallback: ${httpsUrl}`)
  }

  const stdin = process.stdin
  const stdout = process.stdout
  const stderr = process.stderr

  let buffer = Buffer.alloc(0)

  const commandHandler = async (chunk) => {
    const chunkBuf = Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk)
    buffer = Buffer.concat([buffer, chunkBuf])

    let newlineIdx
    while ((newlineIdx = buffer.indexOf(0x0a)) !== -1) {
      const line = buffer.slice(0, newlineIdx).toString('utf-8').trim()
      buffer = buffer.slice(newlineIdx + 1)

      if (line === '') continue

      const shouldPipe = await handleCommand(line, key, repo, httpsUrl, stdout, stderr)
      if (shouldPipe) {
        // CRITICAL: Remove this listener before piping starts.
        // In streamx, .on('data') and .pipe() compete for data.
        // If both are active, the data handler consumes chunks
        // that should flow through the pipe, breaking push.
        stdin.removeListener('data', commandHandler)
        return
      }
    }
  }

  stdin.on('data', commandHandler)

  stdin.on('end', () => {
    process.exit(0)
  })
}

async function handleCommand(command, serverKey, repoName, httpsUrl, stdout, stderr) {
  const [cmd, ...args] = command.split(' ')

  switch (cmd) {
    case 'capabilities':
      stdout.write('connect\n')
      stdout.write('\n')
      return false

    case 'connect':
      const service = args[0]
      await handleConnect(service, serverKey, repoName, httpsUrl, stdout, stderr)
      return true

    case 'list':
      stderr.write('[punch] list not implemented, use connect\n')
      stdout.write('\n')
      return false

    default:
      stderr.write(`[punch] Unknown command: ${cmd}\n`)
      process.exit(1)
      return false
  }
}

async function handleConnect(service, serverKey, repoName, httpsUrl, stdout, stderr) {
  stderr.write(`[punch] Connecting to ${serverKey.slice(0, 8)}.../${repoName}\n`)

  const connector = new TopicConnector({ timeout: 15000 })
  await connector.init()

  try {
    stderr.write('[punch] Searching for peers...\n')
    const conn = await connector.connect(serverKey, repoName)
    stderr.write('[punch] Connected via P2P!\n')

    const client = new GitP2PClient()
    await client.initiate(conn, service, repoName)

    // Remove ALL listeners from stdin before forwarding
    process.stdin.removeAllListeners('data')
    process.stdin.removeAllListeners('end')

    // No connection timeout — large repos (1+ GB) can transfer for minutes.
    // Backpressure keeps data flowing; stale connections are detected by
    // the stream's error/close events.

    // Tell git we're ready FIRST (before any data forwarding)
    // This ensures '\n' precedes ref advertisement on stdout
    stdout.write('\n')

    let cleaningUp = false
    function cleanup (code) {
      if (cleaningUp) return
      cleaningUp = true
      // Graceful teardown — destroy swarm properly.
      // Requires udx-native >= 1.20.3 (libudx 0420f62) which fixes
      // use-after-free and double-free bugs in stream teardown.
      connector.destroy().catch(() => {}).then(() => process.exit(code))
    }

    // Manual bidirectional forwarding — NOT pipe()!
    // streamx pipe() unconditionally calls dest.end() when source ends,
    // and SecretStream._final() closes both directions of the noise stream.
    // This kills push (server can't send status after client sends pack).
    //
    // Backpressure: when write() returns false, pause the source.
    // Resume on 'drain'. Without this, large repos overflow the send
    // buffer and cause "unexpected disconnect" / "bad pack header".
    let stdinEnded = false
    process.stdin.on('data', (chunk) => {
      if (!conn.write(chunk)) {
        process.stdin.pause()
      }
    })
    conn.on('drain', () => {
      if (!stdinEnded) process.stdin.resume()
    })

    process.stdin.on('end', () => {
      stdinEnded = true
      conn.end()
      // Safety: if conn.close doesn't fire within 10s after stdin ends, force exit.
      // This prevents io_uring spin when SecretStream teardown races.
      setTimeout(() => cleanup(0), 10000).unref()
    })

    conn.on('data', (chunk) => {
      if (!stdout.write(chunk)) {
        conn.pause()
      }
    })
    stdout.on('drain', () => conn.resume())

    conn.on('close', () => cleanup(0))

    conn.on('error', (err) => {
      stderr.write(`[punch] Connection error: ${err.message}\n`)
      cleanup(128)
    })

  } catch (err) {
    stderr.write(`[punch] P2P connection failed: ${err.message}\n`)

    // Destroy swarm before HTTPS fallback. Hard kill timeout as
    // fallback — connector.destroy() can trigger the libudx double-free.
    const hardKill = setTimeout(() => process.exit(128), 5000)
    hardKill.unref()
    try { await connector.destroy() } catch {}
    clearTimeout(hardKill)

    if (httpsUrl) {
      stderr.write(`[punch] Falling back to HTTPS: ${httpsUrl}\n`)
      await handleHttpsFallback(service, httpsUrl, stdout, stderr)
    } else {
      stderr.write('[punch] No HTTPS fallback available\n')
      process.exit(128)
    }
  }
}

async function handleHttpsFallback(service, httpsUrl, stdout, stderr) {
  const proc = spawn('git-remote-https', ['origin', httpsUrl], {
    stdio: ['pipe', 'pipe', 'pipe']
  })

  proc.stdin.write(`connect ${service}\n`)

  process.stdin.pipe(proc.stdin)
  proc.stdout.pipe(stdout)

  proc.stderr.on('data', (data) => {
    const msg = data.toString()
    if (msg.includes('error') || msg.includes('fatal')) {
      stderr.write(data)
    }
  })

  proc.on('close', (code) => {
    if (code !== 0) {
      stderr.write(`[punch] HTTPS fallback exited with code ${code}\n`)
    }
    process.exit(code || 0)
  })

  proc.on('error', (err) => {
    stderr.write(`[punch] HTTPS fallback error: ${err.message}\n`)
    process.exit(128)
  })
}

main().catch(err => {
  console.error(`[punch] Fatal error: ${err.message}`)
  process.exit(1)
})