From cc394973d41f881b9bf6254d75a8eb0614c7b747 Mon Sep 17 00:00:00 2001
From: Xiao Ma <xiaom@google.com>
Date: Thu, 9 Apr 2020 01:55:06 +0000
Subject: Add a new field changePrefixOnDecline in DhcpServingParamsParcel.

A new boolean flag (changePrefixOnDecline) to be added in
the DhcpServingParamsParcel, indicating whether or not the DHCP
server should request a new prefix (e.g. a different subnet
prefix) from IpServer when receiving DHCPDECLINE message.

Bug: 130741856
Test: atest NetworkStackTests NetworkStackNextTests
Merged-In: I8cb0f844ef98a5f17d4e07e1812a1abf73aa4c07
Change-Id: I8cb0f844ef98a5f17d4e07e1812a1abf73aa4c07
---
 src/android/net/dhcp/DhcpServingParams.java | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

(limited to 'src')

diff --git a/src/android/net/dhcp/DhcpServingParams.java b/src/android/net/dhcp/DhcpServingParams.java
index 63f847d..c52cae9 100644
--- a/src/android/net/dhcp/DhcpServingParams.java
+++ b/src/android/net/dhcp/DhcpServingParams.java
@@ -90,6 +90,13 @@ public class DhcpServingParams {
     @Nullable
     public final Inet4Address clientAddr;
 
+    /**
+     * Indicates whether the DHCP server should request a new prefix from IpServer when receiving
+     * DHCPDECLINE message in certain particular link (e.g. there is only one downstream USB
+     * tethering client). If it's false, process DHCPDECLINE message as RFC2131#4.3.3 suggests.
+     */
+    public final boolean changePrefixOnDecline;
+
     /**
      * Checked exception thrown when some parameters used to build {@link DhcpServingParams} are
      * missing or invalid.
@@ -103,7 +110,8 @@ public class DhcpServingParams {
     private DhcpServingParams(@NonNull LinkAddress serverAddr,
             @NonNull Set<Inet4Address> defaultRouters,
             @NonNull Set<Inet4Address> dnsServers, @NonNull Set<Inet4Address> excludedAddrs,
-            long dhcpLeaseTimeSecs, int linkMtu, boolean metered, Inet4Address clientAddr) {
+            long dhcpLeaseTimeSecs, int linkMtu, boolean metered, Inet4Address clientAddr,
+            boolean changePrefixOnDecline) {
         this.serverAddr = serverAddr;
         this.defaultRouters = defaultRouters;
         this.dnsServers = dnsServers;
@@ -112,6 +120,7 @@ public class DhcpServingParams {
         this.linkMtu = linkMtu;
         this.metered = metered;
         this.clientAddr = clientAddr;
+        this.changePrefixOnDecline = changePrefixOnDecline;
     }
 
     /**
@@ -140,6 +149,7 @@ public class DhcpServingParams {
                 .setLinkMtu(parcel.linkMtu)
                 .setMetered(parcel.metered)
                 .setClientAddr(clientAddr)
+                .setChangePrefixOnDecline(parcel.changePrefixOnDecline)
                 .build();
     }
 
@@ -195,6 +205,7 @@ public class DhcpServingParams {
         private int mLinkMtu = MTU_UNSET;
         private boolean mMetered;
         private Inet4Address mClientAddr;
+        private boolean mChangePrefixOnDecline;
 
         /**
          * Set the server address and served prefix for the DHCP server.
@@ -328,6 +339,17 @@ public class DhcpServingParams {
             return this;
         }
 
+        /**
+         * Set whether the DHCP server should request a new prefix from IpServer when receiving
+         * DHCPDECLINE message in certain particular link.
+         *
+         * <p>If not set, the default value is false.
+         */
+        public Builder setChangePrefixOnDecline(boolean changePrefixOnDecline) {
+            this.mChangePrefixOnDecline = changePrefixOnDecline;
+            return this;
+        }
+
         /**
          * Create a new {@link DhcpServingParams} instance based on parameters set in the builder.
          *
@@ -382,7 +404,7 @@ public class DhcpServingParams {
                     Collections.unmodifiableSet(new HashSet<>(mDefaultRouters)),
                     Collections.unmodifiableSet(new HashSet<>(mDnsServers)),
                     Collections.unmodifiableSet(excl),
-                    mDhcpLeaseTimeSecs, mLinkMtu, mMetered, mClientAddr);
+                    mDhcpLeaseTimeSecs, mLinkMtu, mMetered, mClientAddr, mChangePrefixOnDecline);
         }
     }
 
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