Allow "_" in URIs.

Note that this is contrary to RFC-2396, which only allows alphanumeric
characters and hyphens. We need this change because internet hosts out
there clearly don't care enough about standards.

bug: 18023709

Change-Id: I9459f58d49ccc68af887a14c889eaa60b6c3150d

2 files changed, 10 insertions, 3 deletions

diff --git a/luni/src/main/java/java/net/URI.java b/luni/src/main/java/java/net/URI.java
index f206473..60bb5db 100644
--- a/luni/src/main/java/java/net/URI.java
+++ b/luni/src/main/java/java/net/URI.java
@@ -571,7 +571,10 @@ public final class URI implements Comparable<URI>, Serializable {
 
     private boolean isValidDomainName(String host) {
         try {
-            UriCodec.validateSimple(host, "-.");
+            // The RFCs don't permit underscores in hostnames, but URI has to because
+            // a certain large website doesn't seem to care about standards and specs.
+            // See bugs 18023709, 17579865 and 18016625.
+            UriCodec.validateSimple(host, "_-.");
         } catch (URISyntaxException e) {
             return false;
         }
diff --git a/luni/src/test/java/libcore/java/net/URITest.java b/luni/src/test/java/libcore/java/net/URITest.java
index 7f4c086..c87433a 100644
--- a/luni/src/test/java/libcore/java/net/URITest.java
+++ b/luni/src/test/java/libcore/java/net/URITest.java
@@ -702,11 +702,15 @@ public final class URITest extends TestCase {
     }
 
     // http://code.google.com/p/android/issues/detail?id=37577
+    // http://b/18023709
+    // http://b/17579865
+    // http://b/18016625
     public void testUnderscore() throws Exception {
         URI uri = new URI("http://a_b.c.d.net/");
         assertEquals("a_b.c.d.net", uri.getAuthority());
-        // The RFC's don't permit underscores in hostnames, and neither does URI (unlike URL).
-        assertNull(uri.getHost());
+        // The RFC's don't permit underscores in hostnames, but URI has to because
+        // a certain large website doesn't seem to care about standards and specs.
+        assertEquals("a_b.c.d.net", uri.getHost());
     }
 
     // Adding a new test? Consider adding an equivalent test to URLTest.java