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From 6cad0f543ccac5abd35a3a617fab72a9c8c64155 Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Wed, 24 Jul 2024 12:06:47 +0200
Subject: [PATCH 06/12] resolv: Do not wait for non-existing second DNS
response after error (bug 30081)
In single-request mode, there is no second response after an error
because the second query has not been sent yet. Waiting for it
introduces an unnecessary timeout.
Reviewed-by: DJ Delorie <dj@redhat.com>
(cherry picked from commit af625987d619388a100b153520d3ee308bda9889)
---
NEWS | 1 +
resolv/Makefile | 3 +
resolv/res_send.c | 2 +-
resolv/tst-resolv-semi-failure.c | 133 +++++++++++++++++++++++++++++
resolv/tst-resolv-short-response.c | 12 +++
5 files changed, 150 insertions(+), 1 deletion(-)
create mode 100644 resolv/tst-resolv-semi-failure.c
diff --git a/NEWS b/NEWS
index c331604747..4156a017ac 100644
--- a/NEWS
+++ b/NEWS
@@ -37,6 +37,7 @@ Security related changes:
The following bugs are resolved with this release:
[29039] Corrupt DTV after reuse of a TLS module ID following dlclose with unused TLS
+ [30081] resolv: Do not wait for non-existing second DNS response after error
[30694] The iconv program no longer tells the user which given encoding name was wrong
[30709] nscd fails to build with cleanup handler if built with -fexceptions
[30721] x86_64: Fix build with --disable-multiarch
diff --git a/resolv/Makefile b/resolv/Makefile
index cca0748f9a..b53a5fcfdb 100644
--- a/resolv/Makefile
+++ b/resolv/Makefile
@@ -106,6 +106,7 @@ tests += \
tst-resolv-nondecimal \
tst-resolv-res_init-multi \
tst-resolv-search \
+ tst-resolv-semi-failure \
tst-resolv-short-response \
tst-resolv-trailing \
@@ -300,6 +301,8 @@ $(objpfx)tst-resolv-nondecimal: $(objpfx)libresolv.so $(shared-thread-library)
$(objpfx)tst-resolv-qtypes: $(objpfx)libresolv.so $(shared-thread-library)
$(objpfx)tst-resolv-rotate: $(objpfx)libresolv.so $(shared-thread-library)
$(objpfx)tst-resolv-search: $(objpfx)libresolv.so $(shared-thread-library)
+$(objpfx)tst-resolv-semi-failure: $(objpfx)libresolv.so \
+ $(shared-thread-library)
$(objpfx)tst-resolv-short-response: $(objpfx)libresolv.so \
$(shared-thread-library)
$(objpfx)tst-resolv-trailing: $(objpfx)libresolv.so $(shared-thread-library)
diff --git a/resolv/res_send.c b/resolv/res_send.c
index bf4ce67b1d..b741b42cae 100644
--- a/resolv/res_send.c
+++ b/resolv/res_send.c
@@ -1236,7 +1236,7 @@ send_dg(res_state statp,
*resplen2 = 0;
return resplen;
}
- if (buf2 != NULL)
+ if (buf2 != NULL && !single_request)
{
/* No data from the first reply. */
resplen = 0;
diff --git a/resolv/tst-resolv-semi-failure.c b/resolv/tst-resolv-semi-failure.c
new file mode 100644
index 0000000000..aa9798b5a7
--- /dev/null
+++ b/resolv/tst-resolv-semi-failure.c
@@ -0,0 +1,133 @@
+/* Test parallel failure/success responses (bug 30081).
+ Copyright (C) 2024 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
+ <https://www.gnu.org/licenses/>. */
+
+#include <resolv.h>
+#include <support/check.h>
+#include <support/resolv_test.h>
+#include <support/check_nss.h>
+
+/* The rcode in the initial response. */
+static volatile int rcode;
+
+/* Whether to fail the initial A query (!fail_aaaa) or the initial
+ AAAA query (fail_aaaa). */
+static volatile bool fail_aaaa;
+
+static void
+response (const struct resolv_response_context *ctx,
+ struct resolv_response_builder *b,
+ const char *qname, uint16_t qclass, uint16_t qtype)
+{
+ /* Handle the failing query. */
+ if ((fail_aaaa && qtype == T_AAAA) && ctx->server_index == 0)
+ {
+ struct resolv_response_flags flags = {.rcode = rcode};
+ resolv_response_init (b, flags);
+ return;
+ }
+
+ /* Otherwise produce a response. */
+ resolv_response_init (b, (struct resolv_response_flags) {});
+ resolv_response_add_question (b, qname, qclass, qtype);
+ resolv_response_section (b, ns_s_an);
+ resolv_response_open_record (b, qname, qclass, qtype, 0);
+ switch (qtype)
+ {
+ case T_A:
+ {
+ char ipv4[4] = {192, 0, 2, 17};
+ resolv_response_add_data (b, &ipv4, sizeof (ipv4));
+ }
+ break;
+ case T_AAAA:
+ {
+ char ipv6[16]
+ = {0x20, 0x01, 0xd, 0xb8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
+ resolv_response_add_data (b, &ipv6, sizeof (ipv6));
+ }
+ break;
+ default:
+ FAIL_EXIT1 ("unexpected TYPE%d query", qtype);
+ }
+ resolv_response_close_record (b);
+}
+
+static void
+check_one (void)
+{
+
+ /* The buggy 1-second query timeout results in 30 seconds of delay,
+ which triggers are test timeout failure. */
+ for (int i = 0; i < 30; ++i)
+ {
+ static const struct addrinfo hints =
+ {
+ .ai_family = AF_UNSPEC,
+ .ai_socktype = SOCK_STREAM,
+ };
+ struct addrinfo *ai;
+ int ret = getaddrinfo ("www.example", "80", &hints, &ai);
+ const char *expected;
+ if (ret == 0 && ai->ai_next != NULL)
+ expected = ("address: STREAM/TCP 192.0.2.17 80\n"
+ "address: STREAM/TCP 2001:db8::1 80\n");
+ else
+ /* Only one response because the AAAA lookup failure is
+ treated as an ignoreable error. */
+ expected = "address: STREAM/TCP 192.0.2.17 80\n";
+ check_addrinfo ("www.example", ai, ret, expected);
+ if (ret == 0)
+ freeaddrinfo (ai);
+ }
+}
+
+static int
+do_test (void)
+{
+ for (int do_single_lookup = 0; do_single_lookup < 2; ++do_single_lookup)
+ {
+ struct resolv_test *aux = resolv_test_start
+ ((struct resolv_redirect_config)
+ {
+ .response_callback = response,
+ });
+
+ if (do_single_lookup)
+ _res.options |= RES_SNGLKUP;
+
+ for (int do_fail_aaaa = 0; do_fail_aaaa < 2; ++do_fail_aaaa)
+ {
+ fail_aaaa = do_fail_aaaa;
+
+ rcode = 2; /* SERVFAIL. */
+ check_one ();
+
+ rcode = 4; /* NOTIMP. */
+ check_one ();
+
+ rcode = 5; /* REFUSED. */
+ check_one ();
+ }
+
+ resolv_test_end (aux);
+ }
+
+ return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/resolv/tst-resolv-short-response.c b/resolv/tst-resolv-short-response.c
index cf1e39876f..be354ae1c7 100644
--- a/resolv/tst-resolv-short-response.c
+++ b/resolv/tst-resolv-short-response.c
@@ -81,6 +81,18 @@ check_one (void)
check_hostent ("www.example", gethostbyname2 ("www.example", AF_INET6),
"name: www.example\n"
"address: 2001:db8::1\n");
+ static const struct addrinfo hints =
+ {
+ .ai_family = AF_UNSPEC,
+ .ai_socktype = SOCK_STREAM,
+ };
+ struct addrinfo *ai;
+ int ret = getaddrinfo ("www.example", "80", &hints, &ai);
+ check_addrinfo ("www.example", ai, ret,
+ "address: STREAM/TCP 192.0.2.17 80\n"
+ "address: STREAM/TCP 2001:db8::1 80\n");
+ if (ret == 0)
+ freeaddrinfo (ai);
}
}
--
2.33.0
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