IDN: Fix handling of long domain names.

Fix merge conflict into mnc-mr1-release
We were incorrectly using sizeof() to calculate the size of the
output array. Note that this change also changes the output size
to 512 to minimize behavioural differences (especially wrt. ICU
checks on sizes).

bug: 30765246
Change-Id: I5d28ddc45d2d6d2bed3e479ca195ed2779b906ed
(cherry picked from commit a1e0873b)

luni/src/main/native/libcore_icu_NativeIDN.cpp

@@ -37,7 +37,8 @@ static jstring NativeIDN_convertImpl(JNIEnv* env, jclass, jstring javaSrc, jint
     if (src.get() == NULL) {
         return NULL;
     }
-    UChar dst[256];
+    static const size_t kDstSize = 512;
+    UChar dst[kDstSize];
     UErrorCode status = U_ZERO_ERROR;
 
     // We're stuck implementing IDNA-2003 for now since that's what we specify.
@@ -47,10 +48,10 @@ static jstring NativeIDN_convertImpl(JNIEnv* env, jclass, jstring javaSrc, jint
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
     size_t resultLength = toAscii
-        ? uidna_IDNToASCII(src.get(), src.size(), &dst[0], sizeof(dst), flags, NULL, &status)
-        : uidna_IDNToUnicode(src.get(), src.size(), &dst[0], sizeof(dst), flags, NULL, &status);
+        ? uidna_IDNToASCII(src.get(), src.size(), &dst[0], kDstSize, flags, NULL, &status)
+        : uidna_IDNToUnicode(src.get(), src.size(), &dst[0], kDstSize, flags, NULL, &status);
 #pragma GCC diagnostic pop
-
+    
     if (U_FAILURE(status)) {
         jniThrowException(env, "java/lang/IllegalArgumentException", u_errorName(status));
         return NULL;

luni/src/test/java/libcore/java/net/IDNTest.java

@@ -37,4 +37,15 @@ public class IDNTest extends TestCase {
         String longInput = makePunyString(512);
         assertEquals(longInput, IDN.toUnicode(longInput));
     }
+
+    // http://b/30765246
+    public void testLongDomainName() {
+        String label63 = "123456789-123456789-123456789-123456789-123456789-123456789-123";
+        String host255 = label63 + "." + label63 + "." + label63 + "." + label63;
+        try {
+            IDN.toASCII(host255.substring(3) + ".com");
+            fail();
+        } catch (IllegalArgumentException expected) {
+        }
+    }
 }