resolv: Support binary labels in test framework

The old implementation based on hsearch_r used an ad-hoc C string
encoding and produced an incorrect format on the wire for domain
names which contained bytes which needed escaping when printed.

This commit switches to ns_name_pton for the wire format conversion
(now that we have separate tests for it) and uses a tsearch tree
with a suitable comparison function to locate compression targets.

2 files changed, 122 insertions, 0 deletions

diff --git a/resolv/Makefile b/resolv/Makefile
index b98e68f..6e70ae9 100644
--- a/resolv/Makefile
+++ b/resolv/Makefile
@@ -51,6 +51,7 @@ tests += \
   tst-res_hnok \
   tst-res_use_inet6 \
   tst-resolv-basic \
+  tst-resolv-binary \
   tst-resolv-edns \
   tst-resolv-network \
   tst-resolv-res_init-multi \
@@ -159,6 +160,7 @@ $(objpfx)tst-bug18665-tcp: $(objpfx)libresolv.so $(shared-thread-library)
 $(objpfx)tst-bug18665: $(objpfx)libresolv.so $(shared-thread-library)
 $(objpfx)tst-res_use_inet6: $(objpfx)libresolv.so $(shared-thread-library)
 $(objpfx)tst-resolv-basic: $(objpfx)libresolv.so $(shared-thread-library)
+$(objpfx)tst-resolv-binary: $(objpfx)libresolv.so $(shared-thread-library)
 $(objpfx)tst-resolv-edns: $(objpfx)libresolv.so $(shared-thread-library)
 $(objpfx)tst-resolv-network: $(objpfx)libresolv.so $(shared-thread-library)
 $(objpfx)tst-resolv-res_init: $(libdl) $(objpfx)libresolv.so
diff --git a/resolv/tst-resolv-binary.c b/resolv/tst-resolv-binary.c
new file mode 100644
index 0000000..e7e6d87
--- /dev/null
+++ b/resolv/tst-resolv-binary.c
@@ -0,0 +1,120 @@
+/* Test handling of binary domain names with res_send.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <resolv.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/resolv_test.h>
+
+static void
+response (const struct resolv_response_context *ctx,
+          struct resolv_response_builder *b,
+          const char *qname, uint16_t qclass, uint16_t qtype)
+{
+  TEST_COMPARE (qclass, C_IN);
+  TEST_COMPARE (qtype, T_TXT);
+  TEST_VERIFY (strlen (qname) <= 255);
+
+  struct resolv_response_flags flags = { 0 };
+  resolv_response_init (b, flags);
+  resolv_response_add_question (b, qname, qclass, qtype);
+  resolv_response_section (b, ns_s_an);
+  resolv_response_open_record (b, qname, qclass, T_TXT, 0x12345678);
+  unsigned char qnamelen = strlen (qname);
+  resolv_response_add_data (b, &qnamelen, 1);
+  resolv_response_add_data (b, qname, qnamelen);
+  resolv_response_close_record (b);
+}
+
+static int
+do_test (void)
+{
+  struct resolv_test *aux = resolv_test_start
+    ((struct resolv_redirect_config)
+     {
+       .response_callback = response,
+     });
+
+  for (int b = 0; b <= 255; ++b)
+    {
+      unsigned char query[] =
+        {
+          b, b,                 /* Transaction ID.  */
+          1, 0,                 /* Query with RD flag.  */
+          0, 1,                 /* One question.  */
+          0, 0, 0, 0, 0, 0,     /* The other sections are empty.  */
+          1, b, 7, 'e', 'x', 'a', 'm', 'p', 'l', 'e', 0,
+          0, T_TXT,             /* TXT query.  */
+          0, 1,                 /* Class IN.  */
+        };
+      unsigned char response[512];
+      int ret = res_send (query, sizeof (query), response, sizeof (response));
+
+      char expected_name[20];
+      /* The name is uncompressed in the query, so we can reference it
+         directly.  */
+      TEST_VERIFY_EXIT (ns_name_ntop (query + 12, expected_name,
+                                      sizeof (expected_name)) >= 0);
+      TEST_COMPARE (ret,
+                    (ssize_t) sizeof (query)
+                    + 2             /* Compression reference.  */
+                    + 2 + 2 + 4 + 2 /* Type, class, TTL, RDATA length.  */
+                    + 1             /* Pascal-style string length.  */
+                    + strlen (expected_name));
+
+      /* Mark as answer, with recursion available, and one answer.  */
+      query[2] = 0x81;
+      query[3] = 0x80;
+      query[7] = 1;
+
+      /* Prefix of the response must match the query.  */
+      TEST_COMPARE (memcmp (response, query, sizeof (query)), 0);
+
+      /* The actual answer follows, starting with the compression
+         reference.  */
+      unsigned char *p = response + sizeof (query);
+      TEST_COMPARE (*p++, 0xc0);
+      TEST_COMPARE (*p++, 0x0c);
+
+      /* Type and class.  */
+      TEST_COMPARE (*p++, 0);
+      TEST_COMPARE (*p++, T_TXT);
+      TEST_COMPARE (*p++, 0);
+      TEST_COMPARE (*p++, C_IN);
+
+      /* TTL.  */
+      TEST_COMPARE (*p++, 0x12);
+      TEST_COMPARE (*p++, 0x34);
+      TEST_COMPARE (*p++, 0x56);
+      TEST_COMPARE (*p++, 0x78);
+
+      /* RDATA length.  */
+      TEST_COMPARE (*p++, 0);
+      TEST_COMPARE (*p++, 1 + strlen (expected_name));
+
+      /* RDATA.  */
+      TEST_COMPARE (*p++, strlen (expected_name));
+      TEST_COMPARE (memcmp (p, expected_name, strlen (expected_name)), 0);
+    }
+
+  resolv_test_end (aux);
+
+  return 0;
+}
+
+#include <support/test-driver.c>