ConnectivityService: add support to set TCP initial rwnd

The value for the TCP initial receive window comes from,
in order,

kernel
  /proc/sys/net/ipv4/tcp_default_init_rwnd

init.rc (via properties)
  net.tcp.default_init_rwnd

properties
  net.tcp.default_init_rwnd

gservices
  Settings.Global.TCP_DEFAULT_INIT_RWND

Bug: 12020135
Change-Id: I0e271be19472900fa9f3bab037d53383ec014a9e

1 files changed, 9 insertions, 0 deletions

diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index b56923f..342336e 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -2669,6 +2669,15 @@ public class ConnectivityService extends IConnectivityManager.Stub {
             }
             setBufferSize(bufferSizes);
         }
+
+        final String defaultRwndKey = "net.tcp.default_init_rwnd";
+        int defaultRwndValue = SystemProperties.getInt(defaultRwndKey, 0);
+        Integer rwndValue = Settings.Global.getInt(mContext.getContentResolver(),
+            Settings.Global.TCP_DEFAULT_INIT_RWND, defaultRwndValue);
+        final String sysctlKey = "sys.sysctl.tcp_def_init_rwnd";
+        if (rwndValue != 0) {
+            SystemProperties.set(sysctlKey, rwndValue.toString());
+        }
     }
 
     /**