* RouterAddress:

- Deprecate some setters
  - Add warning about setCost()
  - Change cost storage from int to short
  - Cost range checks
* NTCP:
  - Republish even if only changing cost
* Transports:
  - Sort multiple peer addresses by cost, with adjustment for local IPv6 preference
  - Add default IPv6Config for ease of changing later

core/java/src/net/i2p/data/RouterAddress.java

@@ -38,7 +38,7 @@ import net.i2p.util.OrderedProperties;
  * @author jrandom
  */
 public class RouterAddress extends DataStructureImpl {
-    private int _cost;
+    private short _cost;
     //private Date _expiration;
     private String _transportStyle;
     private final Properties _options;
@@ -50,19 +50,21 @@ public class RouterAddress extends DataStructureImpl {
     public static final String PROP_PORT = "port";
 
     public RouterAddress() {
-        _cost = -1;
         _options = new OrderedProperties();
     }
 
     /**
      *  For efficiency when created by a Transport.
      *  @param options not copied; do not reuse or modify
+     *  @param cost 0-255
      *  @since IPv6
      */
     public RouterAddress(String style, OrderedProperties options, int cost) {
         _transportStyle = style;
         _options = options;
-        _cost = cost;
+        if (cost < 0 || cost > 255)
+            throw new IllegalArgumentException();
+        _cost = (short) cost;
     }
 
     /**
@@ -71,6 +73,7 @@ public class RouterAddress extends DataStructureImpl {
      * No value above 255 is allowed.
      *
      * Unused before 0.7.12
+     * @return 0-255
      */
     public int getCost() {
         return _cost;
@@ -78,12 +81,18 @@ public class RouterAddress extends DataStructureImpl {
 
     /**
      * Configure the weighted cost of using the address.
-     * No value above 255 is allowed.
+     * No value negative or above 255 is allowed.
+     *
+     * WARNING - do not change cost on a published address or it will break the RI sig.
+     * There is no check here.
+     * Rarely used, use 3-arg constructor.
      *
      * NTCP is set to 10 and SSU to 5 by default, unused before 0.7.12
      */
     public void setCost(int cost) {
-        _cost = cost;
+        if (cost < 0 || cost > 255)
+            throw new IllegalArgumentException();
+        _cost = (short) cost;
     }
 
     /**
@@ -124,6 +133,7 @@ public class RouterAddress extends DataStructureImpl {
      * Configure the type of transport that must be used to communicate on this address
      *
      * @throws IllegalStateException if was already set
+     * @deprecated unused, use 3-arg constructor
      */
     public void setTransportStyle(String transportStyle) {
         if (_transportStyle != null)
@@ -163,6 +173,7 @@ public class RouterAddress extends DataStructureImpl {
      * Makes a copy.
      * @param options non-null
      * @throws IllegalStateException if was already set
+     * @deprecated unused, use 3-arg constructor
      */
     public void setOptions(Properties options) {
         if (!_options.isEmpty())
@@ -234,7 +245,7 @@ public class RouterAddress extends DataStructureImpl {
     public void readBytes(InputStream in) throws DataFormatException, IOException {
         if (_transportStyle != null)
             throw new IllegalStateException();
-        _cost = (int) DataHelper.readLong(in, 1);
+        _cost = (short) DataHelper.readLong(in, 1);
         //_expiration = DataHelper.readDate(in);
         DataHelper.readDate(in);
         _transportStyle = DataHelper.readString(in);
@@ -251,8 +262,8 @@ public class RouterAddress extends DataStructureImpl {
      *  readin and the signature will fail.
      */
     public void writeBytes(OutputStream out) throws DataFormatException, IOException {
-        if ((_cost < 0) || (_transportStyle == null))
+        if (_transportStyle == null)
-            throw new DataFormatException("Not enough data to write a router address");
+            throw new DataFormatException("uninitialized");
         DataHelper.writeLong(out, 1, _cost);
         //DataHelper.writeDate(out, _expiration);
         DataHelper.writeDate(out, null);

router/java/src/net/i2p/router/transport/TransportImpl.java

@@ -14,6 +14,7 @@ import java.net.InetAddress;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.Iterator;
@@ -471,7 +472,8 @@ public abstract class TransportImpl implements Transport {
     }
 
     /** Do we increase the advertised cost when approaching conn limits? */
-    public static final boolean ADJUST_COST = true;
+    protected static final boolean ADJUST_COST = true;
+    protected static final int CONGESTION_COST_ADJUSTMENT = 2;
 
     /**
      *  What addresses are we currently listening to?
@@ -563,6 +565,67 @@ public abstract class TransportImpl implements Transport {
         return rv;
     }
 
+    /**
+     *  Get all available address we can use,
+     *  shuffled and then sorted by cost/preference.
+     *  Lowest cost (most preferred) first.
+     *  @return non-null, possibly empty
+     *  @since IPv6
+     */
+    protected List<RouterAddress> getTargetAddresses(RouterInfo target) {
+        List<RouterAddress> rv = target.getTargetAddresses(getStyle());
+        // Shuffle so everybody doesn't use the first one
+        if (rv.size() > 1) {
+            Collections.shuffle(rv, _context.random());
+            TransportUtil.IPv6Config config = getIPv6Config();
+            int adj;
+            switch (config) {
+              case IPV6_DISABLED:
+                adj = 10; break;
+              case IPV6_NOT_PREFERRED:
+                adj = 1; break;
+              default:
+              case IPV6_ENABLED:
+                adj = 0; break;
+              case IPV6_PREFERRED:
+                adj = -1; break;
+              case IPV6_ONLY:
+                adj = -10; break;
+            }
+            Collections.sort(rv, new AddrComparator(adj));
+        }
+        return rv;
+    }
+
+    /**
+     *  Compare based on published cost, adjusting for our IPv6 preference.
+     *  Lowest cost (most preferred) first.
+     *  @since IPv6
+     */
+    private static class AddrComparator implements Comparator<RouterAddress> {
+        private final int adj;
+
+        public AddrComparator(int ipv6Adjustment) {
+            adj = ipv6Adjustment;
+        }
+
+        public int compare(RouterAddress l, RouterAddress r) {
+            int lc = l.getCost();
+            int rc = r.getCost();
+            byte[] lip = l.getIP();
+            byte[] rip = r.getIP();
+            if (lip != null && lip.length == 16)
+                lc += adj;
+            if (rip != null && rip.length == 16)
+                rc += adj;
+            if (lc > rc)
+                return 1;
+            if (lc < rc)
+                return -1;
+            return 0;
+        }
+    }
+
     /**
      *  Notify a transport of an external address change.
      *  This may be from a local interface, UPnP, a config change, etc.

router/java/src/net/i2p/router/transport/TransportUtil.java

@@ -52,6 +52,7 @@ public abstract class TransportUtil {
     }
 
     private static final Map<String, IPv6Config> BY_NAME = new HashMap<String, IPv6Config>();
+    private static final IPv6Config DEFAULT_IPV6_CONFIG = IPv6Config.IPV6_DISABLED;
 
     static {
         for (IPv6Config cfg : IPv6Config.values()) {
@@ -68,17 +69,17 @@ public abstract class TransportUtil {
         else if (transportStyle.equals("SSU"))
             cfg = ctx.getProperty(SSU_IPV6_CONFIG);
         else
-            return IPv6Config.IPV6_DISABLED;
+            return DEFAULT_IPV6_CONFIG;
         return getIPv6Config(cfg);
     }
 
     public static IPv6Config getIPv6Config(String cfg) {
         if (cfg == null)
-            return IPv6Config.IPV6_DISABLED;
+            return DEFAULT_IPV6_CONFIG;
         IPv6Config c = BY_NAME.get(cfg);
         if (c != null)
             return c;
-        return IPv6Config.IPV6_DISABLED;
+        return DEFAULT_IPV6_CONFIG;
     }
 
     /**

router/java/src/net/i2p/router/transport/ntcp/NTCPTransport.java

@@ -3,6 +3,7 @@ package net.i2p.router.transport.ntcp;
 import java.io.IOException;
 import java.net.InetSocketAddress;
 import java.net.InetAddress;
+import java.net.Inet6Address;
 import java.net.UnknownHostException;
 import java.nio.channels.ServerSocketChannel;
 import java.nio.channels.SocketChannel;
@@ -35,6 +36,8 @@ import net.i2p.router.transport.Transport;
 import static net.i2p.router.transport.Transport.AddressSource.*;
 import net.i2p.router.transport.TransportBid;
 import net.i2p.router.transport.TransportImpl;
+import net.i2p.router.transport.TransportUtil;
+import static net.i2p.router.transport.TransportUtil.IPv6Config.*;
 import net.i2p.router.transport.crypto.DHSessionKeyBuilder;
 import net.i2p.router.transport.udp.UDPTransport;
 import net.i2p.util.Addresses;
@@ -350,7 +353,7 @@ public class NTCPTransport extends TransportImpl {
      *  @since 0.9.6
      */
     private RouterAddress getTargetAddress(RouterInfo target) {
-        List<RouterAddress> addrs = target.getTargetAddresses(STYLE);
+        List<RouterAddress> addrs = getTargetAddresses(target);
         for (int i = 0; i < addrs.size(); i++) {
             RouterAddress addr = addrs.get(i);
             byte[] ip = addr.getIP();
@@ -501,7 +504,8 @@ public class NTCPTransport extends TransportImpl {
                 OrderedProperties props = new OrderedProperties();
                 props.setProperty(RouterAddress.PROP_HOST, ia.getHostAddress());
                 props.setProperty(RouterAddress.PROP_PORT, Integer.toString(port));
-                myAddress = new RouterAddress(STYLE, props, DEFAULT_COST);
+                int cost = getDefaultCost(ia instanceof Inet6Address);
+                myAddress = new RouterAddress(STYLE, props, cost);
                 replaceAddress(myAddress);
             }
         }
@@ -604,7 +608,8 @@ public class NTCPTransport extends TransportImpl {
                     OrderedProperties props = new OrderedProperties();
                     props.setProperty(RouterAddress.PROP_HOST, bindTo);
                     props.setProperty(RouterAddress.PROP_PORT, Integer.toString(port));
-                    myAddress = new RouterAddress(STYLE, props, DEFAULT_COST);
+                    int cost = getDefaultCost(false);
+                    myAddress = new RouterAddress(STYLE, props, cost);
                 }
                 if (!_endpoints.isEmpty()) {
                     // If we are already bound to the new address, OR
@@ -778,10 +783,23 @@ public class NTCPTransport extends TransportImpl {
         OrderedProperties props = new OrderedProperties();
         props.setProperty(RouterAddress.PROP_HOST, name);
         props.setProperty(RouterAddress.PROP_PORT, Integer.toString(p));
-        RouterAddress addr = new RouterAddress(STYLE, props, DEFAULT_COST);
+        int cost = getDefaultCost(false);
+        RouterAddress addr = new RouterAddress(STYLE, props, cost);
         return addr;
     }
     
+    private int getDefaultCost(boolean isIPv6) {
+        int rv = DEFAULT_COST;
+        if (isIPv6) {
+            TransportUtil.IPv6Config config = getIPv6Config();
+            if (config == IPV6_PREFERRED)
+                rv--;
+            else if (config == IPV6_NOT_PREFERRED)
+                rv++;
+        }
+        return rv;
+    }
+
     /**
      *  UDP changed addresses, tell NTCP and (possibly) restart
      *
@@ -831,7 +849,7 @@ public class NTCPTransport extends TransportImpl {
         OrderedProperties newProps = new OrderedProperties();
         int cost;
         if (oldAddr == null) {
-            cost = DEFAULT_COST;
+            cost = getDefaultCost(ip != null && ip.length == 16);
         } else {
             cost = oldAddr.getCost();
             newProps.putAll(oldAddr.getOptionsMap());
@@ -930,21 +948,24 @@ public class NTCPTransport extends TransportImpl {
 
         if (!changed) {
             if (oldAddr != null) {
+                // change cost only?
                 int oldCost = oldAddr.getCost();
-                int newCost = DEFAULT_COST;
+                int newCost = getDefaultCost(ohost != null && ohost.contains(":"));
-                if (TransportImpl.ADJUST_COST && !haveCapacity())
+                if (ADJUST_COST && !haveCapacity())
-                    newCost++;
+                    newCost += CONGESTION_COST_ADJUSTMENT;
                 if (newCost != oldCost) {
-                    oldAddr.setCost(newCost);
+                    newAddr.setCost(newCost);
                     if (_log.shouldLog(Log.WARN))
                         _log.warn("Changing NTCP cost from " + oldCost + " to " + newCost);
+                    // fall thru and republish
                 } else {
                     _log.info("No change to NTCP Address");
+                    return;
                 }
             } else {
                 _log.info("No change to NTCP Address");
+                return;
             }
-            return;
         }
 
         // stopListening stops the pumper, readers, and writers, so required even if

router/java/src/net/i2p/router/transport/udp/UDPTransport.java

@@ -38,6 +38,8 @@ import net.i2p.router.transport.Transport;
 import static net.i2p.router.transport.Transport.AddressSource.*;
 import net.i2p.router.transport.TransportBid;
 import net.i2p.router.transport.TransportImpl;
+import net.i2p.router.transport.TransportUtil;
+import static net.i2p.router.transport.TransportUtil.IPv6Config.*;
 import static net.i2p.router.transport.udp.PeerTestState.Role.*;
 import net.i2p.router.transport.crypto.DHSessionKeyBuilder;
 import net.i2p.router.util.RandomIterator;
@@ -1544,10 +1546,7 @@ public class UDPTransport extends TransportImpl implements TimedWeightedPriority
      *  @since 0.9.6
      */
     RouterAddress getTargetAddress(RouterInfo target) {
-        List<RouterAddress> addrs = target.getTargetAddresses(STYLE);
+        List<RouterAddress> addrs = getTargetAddresses(target);
-        // Shuffle so everybody doesn't use the first one
-        if (addrs.size() > 1)
-            Collections.shuffle(addrs, _context.random());
         for (int i = 0; i < addrs.size(); i++) {
             RouterAddress addr = addrs.get(i);
             if (addr.getOption("ihost0") == null) {
@@ -1821,7 +1820,16 @@ public class UDPTransport extends TransportImpl implements TimedWeightedPriority
             // the whole mechanism is not helpful.
             int cost = DEFAULT_COST;
             if (ADJUST_COST && !haveCapacity(91))
-                cost++;
+                cost += CONGESTION_COST_ADJUSTMENT;
+            if (introducersIncluded)
+                cost += 2;
+            if (isIPv6) {
+                TransportUtil.IPv6Config config = getIPv6Config();
+                if (config == IPV6_PREFERRED)
+                    cost--;
+                else if (config == IPV6_NOT_PREFERRED)
+                    cost++;
+            }
             RouterAddress addr = new RouterAddress(STYLE, options, cost);
 
             RouterAddress current = getCurrentAddress(isIPv6);
@@ -2996,7 +3004,7 @@ public class UDPTransport extends TransportImpl implements TimedWeightedPriority
             if (peerInfo == null)
                 continue;
             ip = null;
-            List<RouterAddress> addrs = peerInfo.getTargetAddresses(STYLE);
+            List<RouterAddress> addrs = getTargetAddresses(peerInfo);
             for (RouterAddress addr : addrs) {
                 ip = addr.getIP();
                 if (ip != null && ip.length == 4)