srt: optional server silence timeout to detect a dead path

library/src/main/java/com/pedro/library/util/streamclient/SrtStreamClient.kt

@@ -73,6 +73,14 @@ class SrtStreamClient(
     srtClient.setLogs(enabled)
   }
 
+  /**
+   * Report a connection failure if the server sends nothing for [millis] (0 = disabled).
+   * See [com.pedro.srt.srt.SrtClient.setServerSilenceTimeout].
+   */
+  fun setServerSilenceTimeout(millis: Long) {
+    srtClient.setServerSilenceTimeout(millis)
+  }
+
   override fun setCheckServerAlive(enabled: Boolean) {
     srtClient.setCheckServerAlive(enabled)
   }

srt/src/main/java/com/pedro/srt/srt/SrtClient.kt

@@ -24,6 +24,7 @@ import com.pedro.common.ConnectionFailed
 import com.pedro.common.UrlParser
 import com.pedro.common.VideoCodec
 import com.pedro.common.frame.MediaFrame
+import com.pedro.common.TimeUtils
 import com.pedro.common.onMainThread
 import com.pedro.common.socket.base.SocketType
 import com.pedro.common.socket.base.StreamSocket
@@ -80,6 +81,7 @@ class SrtClient(private val connectChecker: ConnectChecker) {
   private var jobRetry: Job? = null
 
   private var checkServerAlive = false
+  private var serverSilenceTimeoutMs = 0L
   @Volatile
   var isStreaming = false
     private set
@@ -169,6 +171,19 @@ class SrtClient(private val connectChecker: ConnectChecker) {
     checkServerAlive = enabled
   }
 
+  /**
+   * Report onConnectionFailed("No response from server") if no packet is received from the
+   * server for [millis]. While data is being published, the server acknowledges it with ACK
+   * packets (typically every 10 ms), so a long silence means the path is dead even if sending
+   * does not fail (for example, packets silently dropped by the network).
+   * Unlike [setCheckServerAlive] it needs no ICMP/Echo, which firewalls often block.
+   * Servers only acknowledge received data, so use a value well above the longest pause in
+   * which no media is sent. 0 (default) disables the check.
+   */
+  fun setServerSilenceTimeout(millis: Long) {
+    serverSilenceTimeoutMs = millis
+  }
+
   fun setReTries(reTries: Int) {
     numRetry = reTries
     this.reTries = reTries
@@ -333,11 +348,13 @@ class SrtClient(private val connectChecker: ConnectChecker) {
 
   @Throws(IOException::class)
   private suspend fun handleServerPackets() {
+    var lastServerPacketTs = TimeUtils.getCurrentTimeMillis()
     while (scope.isActive && isStreaming) {
       val error = runCatching {
         if (isAlive()) {
           //ignore packet after connect if tunneled to avoid spam idle
           handleMessages()
+          lastServerPacketTs = TimeUtils.getCurrentTimeMillis()
         } else {
           onMainThread {
             connectChecker.onConnectionFailed("No response from server")
@@ -347,6 +364,12 @@ class SrtClient(private val connectChecker: ConnectChecker) {
       }.exceptionOrNull()
       if (error != null && ConnectionFailed.parse(error.validMessage()) != ConnectionFailed.TIMEOUT) {
         scope.cancel()
+      } else if (error != null && serverSilenceTimeoutMs > 0 &&
+        TimeUtils.getCurrentTimeMillis() - lastServerPacketTs >= serverSilenceTimeoutMs) {
+        onMainThread {
+          connectChecker.onConnectionFailed("No response from server")
+        }
+        scope.cancel()
       }
     }
   }