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Commit 5113da7e authored by Benedict Wong's avatar Benedict Wong
Browse files

Speculatively fix L2TP keepalive issues by reducing mtu 

This change reduces MTU/MRU values for racoon/pppd from 1400 to 1388 in
an attempt to fix keepalive issues experienced in the field.

Bug: 119076193
Test: Speculative change, original issues were not reproducible.
Change-Id: I7731503260fdc8bcbc6c5fcda6991ead6fb7c52e
parent bad5c4ec

services/core/java/com/android/server/connectivity/Vpn.java

+7 −3
Original line number Diff line number Diff line
@@ -2143,7 +2143,11 @@ public class Vpn { 
                break;

        }



        // Prepare arguments for mtpd.

        // Prepare arguments for mtpd. MTU/MRU calculated conservatively. Only IPv4 supported

        // because LegacyVpn.

        // 1500 - 60 (Carrier-internal IPv6 + UDP + GTP) - 10 (PPP) - 16 (L2TP) - 8 (UDP)

        //   - 77 (IPsec w/ SHA-2 512, 256b trunc-len, AES-CBC) - 8 (UDP encap) - 20 (IPv4)

        //   - 28 (464xlat)

        String[] mtpd = null;

        switch (profile.type) {

            case VpnProfile.TYPE_PPTP:
@@ -2151,7 +2155,7 @@ public class Vpn { 
                    iface, "pptp", profile.server, "1723",

                    "name", profile.username, "password", profile.password,

                    "linkname", "vpn", "refuse-eap", "nodefaultroute",

                    "usepeerdns", "idle", "1800", "mtu", "1400", "mru", "1400",

                    "usepeerdns", "idle", "1800", "mtu", "1270", "mru", "1270",

                    (profile.mppe ? "+mppe" : "nomppe"),

                };

                break;
@@ -2161,7 +2165,7 @@ public class Vpn { 
                    iface, "l2tp", profile.server, "1701", profile.l2tpSecret,

                    "name", profile.username, "password", profile.password,

                    "linkname", "vpn", "refuse-eap", "nodefaultroute",

                    "usepeerdns", "idle", "1800", "mtu", "1400", "mru", "1400",

                    "usepeerdns", "idle", "1800", "mtu", "1270", "mru", "1270",

                };

                break;

        }

tests/net/java/com/android/server/connectivity/VpnTest.java

+1 −1
Original line number Diff line number Diff line
@@ -1090,7 +1090,7 @@ public class VpnTest { 
                    new String[] { EGRESS_IFACE, "l2tp", expectedAddr, "1701", profile.l2tpSecret,

                            "name", profile.username, "password", profile.password,

                            "linkname", "vpn", "refuse-eap", "nodefaultroute", "usepeerdns",

                            "idle", "1800", "mtu", "1400", "mru", "1400" },

                            "idle", "1800", "mtu", "1270", "mru", "1270" },

                    deps.mtpdArgs.get(10, TimeUnit.SECONDS));

            // Now wait for the runner to be ready before testing for the route.

            legacyRunnerReady.block(10_000);