small fix

Author: arturobernalg

httpclient5/src/main/java/org/apache/hc/client5/http/AddressSelectingDnsResolver.java

@@ -50,7 +50,7 @@
 import org.slf4j.LoggerFactory;
 
 /**
- * {@code Rfc6724AddressSelectingDnsResolver} wraps a delegate {@link DnsResolver}
+ * {@code AddressSelectingDnsResolver} wraps a delegate {@link DnsResolver}
  * and applies RFC 6724 destination address selection rules (RFC 6724 §6)
  * to the returned addresses. It can also enforce or bias a protocol family preference.
  *
@@ -185,16 +185,10 @@ private static List<InetAddress> filterCandidates(
             final InetAddress[] resolved,
             final ProtocolFamilyPreference pref) {
 
-        final List<InetAddress> out = new ArrayList<>(resolved.length);
-        for (final InetAddress a : resolved) {
-            if (!isUsableDestination(a)) {
-                continue;
-            }
-            if (shouldInclude(pref, a)) {
-                out.add(a);
-            }
-        }
-        return out;
+        return Arrays.stream(resolved)
+                .filter(AddressSelectingDnsResolver::isUsableDestination)
+                .filter(a -> shouldInclude(pref, a))
+                .collect(Collectors.toList());
     }
 
     private static boolean shouldInclude(final ProtocolFamilyPreference pref, final InetAddress a) {
@@ -220,17 +214,9 @@ private List<InetAddress> sortByRfc6724(final List<InetAddress> addrs) {
             LOG.trace("RFC6724 input candidates: {}", fmt(addrs));
         }
 
-        final List<InetSocketAddress> socketAddresses = new ArrayList<>(addrs.size());
-        for (final InetAddress a : addrs) {
-            socketAddresses.add(new InetSocketAddress(a, PROBE_PORT));
-        }
-
-        final List<InetAddress> srcs = inferSourceAddresses(socketAddresses);
-
         final List<Info> infos = new ArrayList<>(addrs.size());
-        for (int i = 0; i < addrs.size(); i++) {
-            final InetAddress dst = addrs.get(i);
-            final InetAddress src = srcs.get(i);
+        for (final InetAddress dst : addrs) {
+            final InetAddress src = inferSourceAddress(new InetSocketAddress(dst, PROBE_PORT));
             infos.add(new Info(dst, src, ipAttrOf(dst), ipAttrOf(src)));
         }
 
@@ -245,10 +231,9 @@ private List<InetAddress> sortByRfc6724(final List<InetAddress> addrs) {
 
         infos.sort(RFC6724_COMPARATOR);
 
-        final List<InetAddress> out = new ArrayList<>(infos.size());
-        for (final Info info : infos) {
-            out.add(info.dst);
-        }
+        final List<InetAddress> out = infos.stream()
+                .map(info -> info.dst)
+                .collect(Collectors.toList());
 
         if (LOG.isTraceEnabled()) {
             LOG.trace("RFC6724 output order: {}", fmt(out));
@@ -257,30 +242,15 @@ private List<InetAddress> sortByRfc6724(final List<InetAddress> addrs) {
         return out;
     }
 
-    private List<InetAddress> inferSourceAddresses(final List<InetSocketAddress> destinations) {
-        final List<InetAddress> srcs = new ArrayList<>(destinations.size());
-
-        for (final InetSocketAddress dest : destinations) {
-            InetAddress src = null;
-            try {
-                src = sourceAddressResolver.resolveSource(dest);
-            } catch (final SocketException ignore) {
-                if (LOG.isTraceEnabled()) {
-                    LOG.trace("RFC6724 could not infer source address for {}: {}", dest, ignore.toString());
-                }
-            }
-            srcs.add(src);
-        }
-
-        if (LOG.isTraceEnabled()) {
-            final List<String> printable = new ArrayList<>(srcs.size());
-            for (final InetAddress a : srcs) {
-                printable.add(addr(a));
+    private InetAddress inferSourceAddress(final InetSocketAddress destination) {
+        try {
+            return sourceAddressResolver.resolveSource(destination);
+        } catch (final SocketException ex) {
+            if (LOG.isTraceEnabled()) {
+                LOG.trace("RFC6724 could not infer source address for {}: {}", destination, ex.toString());
             }
-            LOG.trace("RFC6724 inferred source addresses: {}", printable);
+            return null;
         }
-
-        return srcs;
     }
 
     private static List<InetAddress> applyFamilyPreference(
@@ -388,7 +358,8 @@ private static final class Attr {
         }
     }
 
-    private enum Scope {
+    // Package-private for unit testing.
+    enum Scope {
         INTERFACE_LOCAL(0x1),
         LINK_LOCAL(0x2),
         ADMIN_LOCAL(0x4),
@@ -419,9 +390,12 @@ static Scope fromValue(final int v) {
                 case 0x8: {
                     return ORG_LOCAL;
                 }
-                default: {
+                case 0xe: {
                     return GLOBAL;
                 }
+                default: {
+                    throw new IllegalArgumentException("Unknown scope value: 0x" + Integer.toHexString(v));
+                }
             }
         }
     }
@@ -434,7 +408,8 @@ private static Attr ipAttrOf(final InetAddress ip) {
         return new Attr(classifyScope(ip), e.precedence, e.label);
     }
 
-    private static Scope classifyScope(final InetAddress ip) {
+    // Package-private for unit testing.
+    static Scope classifyScope(final InetAddress ip) {
         if (ip.isLoopbackAddress()) {
             return Scope.INTERFACE_LOCAL;
         }
@@ -443,8 +418,14 @@ private static Scope classifyScope(final InetAddress ip) {
         }
         if (ip.isMulticastAddress()) {
             if (ip instanceof Inet6Address) {
-                // RFC 6724 §3.1 and RFC 4291: low 4 bits of second byte are scope for IPv6 multicast.
-                return Scope.fromValue(ip.getAddress()[1] & 0x0f);
+                // RFC 6724 §3.1 and RFC 4291: low 4 bits of second byte encode scope for IPv6 multicast.
+                // Not all nibble values map to a known Scope constant; treat unknown values as GLOBAL.
+                final int nibble = ip.getAddress()[1] & 0x0f;
+                try {
+                    return Scope.fromValue(nibble);
+                } catch (final IllegalArgumentException e) {
+                    return Scope.GLOBAL;
+                }
             }
             return Scope.GLOBAL;
         }
@@ -466,7 +447,8 @@ private static final class PolicyEntry {
         }
     }
 
-    private static final class Network {
+    // Package-private for unit testing.
+    static final class Network {
         final byte[] ip;
         final int bits;
 
@@ -549,6 +531,11 @@ private static PolicyEntry classify(final InetAddress ip) {
         final int preferB = 1;
 
         // RFC 6724 §6: destination address selection rules.
+        //
+        // Rules 3, 4 and 7 are not implementable with standard JDK APIs:
+        //   Rule 3 (Avoid deprecated source addresses) — InetAddress exposes no deprecation state.
+        //   Rule 4 (Prefer home addresses) — Mobile IPv6 concept; not applicable to an HTTP client.
+        //   Rule 7 (Prefer native transport) — JDK provides no encapsulation/tunneling info.
 
         // Rule 1: Avoid unusable destinations.
         final boolean validA = aSrc != null && !aSrc.isAnyLocalAddress();
@@ -571,6 +558,10 @@ private static PolicyEntry classify(final InetAddress ip) {
             return preferB;
         }
 
+        // Rule 3: Avoid deprecated addresses — skipped (see above).
+
+        // Rule 4: Prefer home addresses — skipped (see above).
+
         // Rule 5: Prefer matching label.
         if (aSrcAttr.label == aDstAttr.label && bSrcAttr.label != bDstAttr.label) {
             return preferA;
@@ -587,6 +578,8 @@ private static PolicyEntry classify(final InetAddress ip) {
             return preferB;
         }
 
+        // Rule 7: Prefer native transport — skipped (see above).
+
         // Rule 8: Prefer smaller scope.
         if (aDstAttr.scope.value < bDstAttr.scope.value) {
             return preferA;
@@ -595,7 +588,7 @@ private static PolicyEntry classify(final InetAddress ip) {
             return preferB;
         }
 
-        // Rule 9: Longest matching prefix (IPv6 only).
+        // Rule 9: Longest matching prefix (IPv6 only, per RFC 6724 §6).
         if (aDst instanceof Inet6Address && bDst instanceof Inet6Address) {
             final int commonA = commonPrefixLen(aSrc, aDst);
             final int commonB = commonPrefixLen(bSrc, bDst);
@@ -645,19 +638,15 @@ static String addr(final InetAddress a) {
     }
 
     static List<String> fmt(final InetAddress[] arr) {
-        final List<String> out = new ArrayList<>(arr.length);
-        for (final InetAddress a : arr) {
-            out.add(addr(a));
-        }
-        return out;
+        return Arrays.stream(arr)
+                .map(AddressSelectingDnsResolver::addr)
+                .collect(Collectors.toList());
     }
 
     static List<String> fmt(final List<InetAddress> arr) {
-        final List<String> out = new ArrayList<>(arr.size());
-        for (final InetAddress a : arr) {
-            out.add(addr(a));
-        }
-        return out;
+        return arr.stream()
+                .map(AddressSelectingDnsResolver::addr)
+                .collect(Collectors.toList());
     }
 
 }