From 84e0e2365ba533fbb247145bc44991ea4b401782 Mon Sep 17 00:00:00 2001
From: Mauro Molin <molmauro@amazon.com>
Date: Thu, 27 Jul 2023 17:10:16 +0100
Subject: [PATCH] Fix Name constructor failing with max length relative name
 and root origin

The Name constructor failed when passing a max-length (253 chars) relative name and Name.root as origin, while this name is technically allowed.

The failure was caused by the Name constructor having the local "absolute" variable wrongly set to false in this case. This change fixes this by updating this flag when the origin is present.

Previous to this fix the workaround was to pass a null origin and manually append the final dot (root) to the string: in this case the constructor would work (as demonstrated by the "ctor_max_length_abs" test.

With this change I've also added a few tests for these edge-cases.
---
 src/main/java/org/xbill/DNS/Name.java     |  1 +
 src/test/java/org/xbill/DNS/NameTest.java | 49 +++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/src/main/java/org/xbill/DNS/Name.java b/src/main/java/org/xbill/DNS/Name.java
index 9c5465fc..0147d0d3 100644
--- a/src/main/java/org/xbill/DNS/Name.java
+++ b/src/main/java/org/xbill/DNS/Name.java
@@ -271,6 +271,7 @@ public Name(String s, Name origin) throws TextParseException {
       appendFromString(s, label, pos);
     }
     if (origin != null && !absolute) {
+      absolute = origin.isAbsolute();
       appendFromString(s, origin.name, origin.labels);
     }
     // A relative name that is MAXNAME octets long is a strange and wonderful thing.
diff --git a/src/test/java/org/xbill/DNS/NameTest.java b/src/test/java/org/xbill/DNS/NameTest.java
index d5986e3a..7ba35f94 100644
--- a/src/test/java/org/xbill/DNS/NameTest.java
+++ b/src/test/java/org/xbill/DNS/NameTest.java
@@ -350,6 +350,55 @@ void ctor_max_length_abs() throws TextParseException {
       assertEquals(255, n.length());
     }
 
+    @Test
+    void ctor_max_length_rel_with_root_origin() throws TextParseException {
+      // relative name with three 63-char labels and a 61-char label with Name.root as origin
+      Name n =
+          new Name(
+              "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb.ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc.ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd",
+              Name.root);
+      assertTrue(n.isAbsolute());
+      assertFalse(n.isWild());
+      assertEquals(5, n.labels());
+      assertEquals(255, n.length());
+    }
+
+    @Test
+    void ctor_max_length_rel_with_abs_origin() throws TextParseException {
+      // relative name with three 63-char labels and a 52-char label with 9-char absolute name as
+      // origin
+      Name n =
+          new Name(
+              "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb.ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc.dddddddddddddddddddddddddddddddddddddddddddddddddddd",
+              Name.fromString("absolute."));
+      assertTrue(n.isAbsolute());
+      assertFalse(n.isWild());
+      assertEquals(6, n.labels());
+      assertEquals(255, n.length());
+    }
+
+    @Test
+    void ctor_too_long_rel_with_rel_origin() throws TextParseException {
+      // relative name with three 63-char labels and a 53-char label with an 8-char relative origin
+      assertThrows(
+          TextParseException.class,
+          () ->
+              new Name(
+                  "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb.ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc.ddddddddddddddddddddddddddddddddddddddddddddddddddddd",
+                  new Name("relative")));
+    }
+
+    @Test
+    void ctor_too_long_rel_with_abs_origin() {
+      // relative name with three 63-char labels and a 53-char label with a 9-char absolute origin
+      assertThrows(
+          TextParseException.class,
+          () ->
+              new Name(
+                  "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb.ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc.ddddddddddddddddddddddddddddddddddddddddddddddddddddd",
+                  new Name("absolute.")));
+    }
+
     @Test
     void ctor_escaped() throws TextParseException {
       Name n = new Name("ab\\123cd");