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| import com.fasterxml.jackson.databind.ObjectMapper import org.slf4j.LoggerFactory import org.springframework.web.socket.* import org.springframework.web.socket.client.WebSocketClient import org.springframework.web.socket.handler.AbstractWebSocketHandler import java.util.concurrent.* import java.util.concurrent.atomic.AtomicBoolean import java.util.concurrent.atomic.AtomicInteger
data class WebSocketProxySession( val session: WebSocketSession, var authorized: Boolean = false, var downConnected: Boolean = false, var lastHeartbeat: Long = System.currentTimeMillis() )
abstract class IWebSocketProxier( val objectMapper: ObjectMapper, private val client: WebSocketClient ) : AbstractWebSocketHandler() { abstract val registerPath: String
open val sessionTimeoutMillis: Long = 10 * 60 * 1000
private val logger = LoggerFactory.getLogger(this::class.java) private val sessions = ConcurrentHashMap<String, WebSocketProxySession>() private val downstreamContexts = ConcurrentHashMap<String, DownstreamContext>() private val scheduler = Executors.newSingleThreadScheduledExecutor( NamedThreadFactory("proxy-session-timeout-") )
init { scheduler.scheduleAtFixedRate( { cleanupExpired() }, sessionTimeoutMillis, sessionTimeoutMillis, TimeUnit.MILLISECONDS ) }
override fun afterConnectionEstablished(session: WebSocketSession) { logger.info("Upstream connected: ${session.id}") sessions[session.id] = WebSocketProxySession(session) onUpstreamOpen(sessions[session.id]!!) }
override fun handleMessage(session: WebSocketSession, message: WebSocketMessage<*>) { val proxy = sessions[session.id] ?: return if (!proxy.authorized) { val ok = onUpstreamFirstMessage(proxy, message) if (!ok) { onUpstreamFirstMessageIsNull(proxy) closeSession(session.id) return } proxy.authorized = true onAuthSuccess(proxy) connectDownstream(session.id) downstreamContexts[session.id]?.pending?.offer(clone(message)) return } val ctx = downstreamContexts[session.id] ?: return if (!ctx.downConnected.get()) { ctx.pending.offer(clone(message)) } else { ctx.sendToDownstream(transformUpstream(message)) } }
override fun afterConnectionClosed(session: WebSocketSession, status: CloseStatus) { logger.info("Upstream closed: ${session.id}") closeSession(session.id) }
fun sendHeartbeat() { val ping = PingMessage() sessions.values.forEach { try { it.session.sendMessage(ping) } catch (_: Exception) { } } }
protected open fun onUpstreamOpen(proxy: WebSocketProxySession) = Unit
protected abstract fun onUpstreamFirstMessage( proxy: WebSocketProxySession, message: WebSocketMessage<*> ): Boolean
protected open fun onUpstreamFirstMessageIsNull(proxy: WebSocketProxySession) { val err = mapOf("finish" to true, "error" to "身份认证失败") proxy.session.sendMessage(TextMessage(objectMapper.writeValueAsString(err))) }
protected open fun onAuthSuccess(proxy: WebSocketProxySession) = Unit
protected abstract fun downstreamUri(proxy: WebSocketProxySession): String
protected abstract fun transformUpstream(message: WebSocketMessage<*>): WebSocketMessage<*>
protected abstract fun transformDownstream(message: WebSocketMessage<*>): WebSocketMessage<*>
protected open fun onSessionClosed(proxy: WebSocketProxySession) = Unit
private fun connectDownstream(sessionId: String) { val proxy = sessions[sessionId]!! val ctx = DownstreamContext(proxy) downstreamContexts[sessionId] = ctx client.execute(object : AbstractWebSocketHandler() { override fun afterConnectionEstablished(down: WebSocketSession) { logger.info("Downstream connected for: $sessionId") ctx.downConnected.set(true) ctx.downstream = down while (true) { val msg = ctx.pending.poll() ?: break ctx.sendToDownstream(transformUpstream(msg)) } }
override fun handleMessage(down: WebSocketSession, msg: WebSocketMessage<*>) { proxy.session.sendMessage(transformDownstream(msg)) }
override fun afterConnectionClosed(down: WebSocketSession, status: CloseStatus) { logger.warn("Downstream closed early: ${status.code}") closeSession(sessionId) } }, downstreamUri(proxy)) }
private fun closeSession(sessionId: String) { sessions.remove(sessionId)?.also { onSessionClosed(it) } downstreamContexts.remove(sessionId)?.closeAll() }
private fun cleanupExpired() { val now = System.currentTimeMillis() sessions.entries .filter { now - it.value.lastHeartbeat > sessionTimeoutMillis } .forEach { closeSession(it.key) } }
private fun clone(msg: WebSocketMessage<*>): WebSocketMessage<*> = when (msg) { is TextMessage -> TextMessage(msg.payload) is BinaryMessage -> BinaryMessage(msg.payload.asReadOnlyBuffer()) else -> msg }
private class DownstreamContext(proxy: WebSocketProxySession) { @Volatile var downstream: WebSocketSession? = null val downConnected = AtomicBoolean(false) val pending = ConcurrentLinkedQueue<WebSocketMessage<*>>() private val executor: ExecutorService = ThreadPoolExecutor( 4, 16, 60, TimeUnit.SECONDS, LinkedBlockingQueue(1000), NamedThreadFactory("proxy-send-${proxy.session.id}") )
fun sendToDownstream(msg: WebSocketMessage<*>) { executor.execute { try { downstream?.sendMessage(msg) } catch (e: Exception) { LoggerFactory.getLogger("DownstreamLogger").error("Send downstream failed", e) } } }
fun closeAll() { try { downstream?.close() } catch (_: Exception) { } executor.shutdownNow() pending.clear() } }
private class NamedThreadFactory(prefix: String) : ThreadFactory { private val cnt = AtomicInteger(1) private val name = "${prefix}-${cnt.getAndIncrement()}" override fun newThread(r: Runnable) = Thread(r, name) } }
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