117 lines
4.5 KiB
Kotlin
117 lines
4.5 KiB
Kotlin
package com.opendance.studio.net
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import android.util.Log
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import kotlinx.coroutines.Dispatchers
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import kotlinx.coroutines.async
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import kotlinx.coroutines.awaitAll
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import kotlinx.coroutines.coroutineScope
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import kotlinx.coroutines.flow.Flow
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import kotlinx.coroutines.flow.flow
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import kotlinx.coroutines.flow.flowOn
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import kotlinx.coroutines.sync.Semaphore
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import kotlinx.coroutines.sync.withPermit
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import kotlinx.coroutines.withContext
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import java.net.Inet4Address
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import java.net.InetSocketAddress
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import java.net.NetworkInterface
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import java.net.Socket
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/**
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* T-AND-006：主机发现
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*
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* Windows 客户端是**裸 WebSocket 服务端**（不是 HTTP 服务），因此不能靠扫描
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* HTTP 端点发现；这里用「TCP 能否连上 8765 端口」作为探测手段。
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*
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* 策略：取手机在 WiFi 网的 IPv4 地址，推导 /24 网段，并发探测该网段内所有
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* 主机的目标端口（默认并发 32、单机超时 300ms，整段约 2~3 秒）。
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*/
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object HostDiscovery {
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private const val TAG = "HostDiscovery"
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const val DEFAULT_PORT = 8765
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private const val CONNECT_TIMEOUT_MS = 300
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private const val MAX_CONCURRENCY = 32
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/** 发现结果 */
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data class Candidate(val ip: String, val port: Int, val latencyMs: Long)
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/** 手机自身的 WiFi IPv4 地址（形如 192.168.1.23），无网络时返回 null */
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suspend fun localIpv4Address(): String? = withContext(Dispatchers.IO) {
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try {
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val candidates = mutableListOf<String>()
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for (nif in NetworkInterface.getNetworkInterfaces()) {
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if (!nif.isUp || nif.isLoopback) continue
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val name = nif.name.lowercase()
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// 排除蜂窝与隧道网卡，优先 WiFi / 以太网
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if (name.startsWith("rmnet") || name.startsWith("dummy") || name.startsWith("tun")) continue
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for (address in nif.inetAddresses) {
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if (address !is Inet4Address || address.isLoopbackAddress) continue
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val ip = address.hostAddress ?: continue
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// 排除链路本地地址（169.254.x.x）
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if (ip.startsWith("169.254.")) continue
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candidates.add(ip)
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}
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}
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// 优先返回私有网段地址；否则退回第一个可用地址
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candidates.firstOrNull { isPrivateIpv4(it) } ?: candidates.firstOrNull()
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} catch (e: Exception) {
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Log.w(TAG, "获取本机地址失败：${e.message}")
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null
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}
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}
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/** 判断是否为 RFC1918 私有地址 */
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fun isPrivateIpv4(ip: String): Boolean {
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val parts = ip.split(".").mapNotNull { it.toIntOrNull() }
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if (parts.size != 4) return false
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val (a, b) = parts[0] to parts[1]
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return a == 10 ||
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(a == 172 && b in 16..31) ||
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(a == 192 && b == 168)
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}
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/** 由本机地址推导 /24 前缀，如 192.168.1.23 → "192.168.1" */
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fun subnetPrefix(ip: String): String? {
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val parts = ip.split(".")
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if (parts.size != 4) return null
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return parts.take(3).joinToString(".")
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}
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/**
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* 扫描网段。以 Flow 形式逐步产出候选，便于 UI 边扫边显示。
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*/
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fun scan(prefix: String, port: Int = DEFAULT_PORT): Flow<Candidate> = flow {
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val semaphore = Semaphore(MAX_CONCURRENCY)
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val candidates = coroutineScope {
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(1..254).map { last ->
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async(Dispatchers.IO) {
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semaphore.withPermit {
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probe("$prefix.$last", port)
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}
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}
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}.awaitAll()
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}
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// 按延迟排序，最快响应的最可能是目标机
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candidates.filterNotNull().sortedBy { it.latencyMs }.forEach { emit(it) }
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}.flowOn(Dispatchers.IO)
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/** 探测单个主机：能建立 TCP 连接即认为端口开放 */
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private fun probe(ip: String, port: Int): Candidate? {
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val started = System.currentTimeMillis()
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return try {
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Socket().use { socket ->
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socket.connect(InetSocketAddress(ip, port), CONNECT_TIMEOUT_MS)
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Candidate(ip, port, System.currentTimeMillis() - started)
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}
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} catch (e: Exception) {
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null
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}
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}
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/** 单个主机连通性检查（连接页「测试连接」用） */
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suspend fun checkHost(ip: String, port: Int = DEFAULT_PORT): Candidate? = withContext(Dispatchers.IO) {
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probe(ip, port)
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}
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}
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