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	This patch adds two tests that verify correct behavior of getaddrinfo when DNS resolution fails with a temporary error. Both tests ensure that getaddrinfo returns EAI_AGAIN in cases where no valid address can be resolved due to network or resolver failure. * tst-getaddrinfo-eai-again.c Runs inside the glibc test-container without any DNS server configured. The test performs queries using AF_INET, AF_INET6, and AF_UNSPEC and verifies that getaddrinfo returns EAI_AGAIN when resolution fails. * tst-getaddrinfo-eai-again-timeout.c Runs outside of the container but uses the resolv_test framework to simulate network failures. The test covers two failure modes: - No response from the server (resolv_response_drop) - Zero-length reply from the server In both cases, getaddrinfo is expected to return EAI_AGAIN. Reviewed-by: Florian Weimer <fweimer@redhat.com>
		
			
				
	
	
		
			123 lines
		
	
	
		
			3.7 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			123 lines
		
	
	
		
			3.7 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
/* Test for BZ #16849. Verify that getaddrinfo correctly returns
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   EAI_AGAIN when DNS resolution fails due to timeout or malformed
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   responses.
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   This test uses two simulated failure modes:
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   - The DNS server does not respond at all (resolv_response_drop).
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   - The DNS server responds with a zero-length packet.
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   Copyright (C) 2025 Free Software Foundation, Inc.
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   This file is part of the GNU C Library.
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   The GNU C Library is free software; you can redistribute it and/or
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   modify it under the terms of the GNU Lesser General Public
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   License as published by the Free Software Foundation; either
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   version 2.1 of the License, or (at your option) any later version.
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   The GNU C Library is distributed in the hope that it will be useful,
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   but WITHOUT ANY WARRANTY; without even the implied warranty of
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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   Lesser General Public License for more details.
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   You should have received a copy of the GNU Lesser General Public
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   License along with the GNU C Library; if not, see
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   <https://www.gnu.org/licenses/>.  */
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#include <netdb.h>
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#include <resolv.h>
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#include <stdbool.h>
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#include <support/check.h>
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#include <support/resolv_test.h>
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/* Track whether the callbacks were actually invoked.  */
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static volatile bool response_called_drop = false;
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static volatile bool response_called_zero_len = false;
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/* Simulate a DNS server that sends a zero-length response.  */
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static void
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response_zero_len (const struct resolv_response_context *ctx,
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                   struct resolv_response_builder *b,
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                   const char *qname, uint16_t qclass, uint16_t qtype)
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{
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  response_called_zero_len = true;
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  /* Do nothing — zero-length reply.  */
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}
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/* Simulate a DNS server that drops the request.  */
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static void
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response_drop (const struct resolv_response_context *ctx,
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               struct resolv_response_builder *b,
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               const char *qname, uint16_t qclass, uint16_t qtype)
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{
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  response_called_drop = true;
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  resolv_response_drop (b);
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}
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/* Query getaddrinfo for multiple families and expect EAI_AGAIN.  */
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static void
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query_host (const char *host_name)
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{
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  int family[] = { AF_INET, AF_INET6, AF_UNSPEC };
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  const char *family_names[] = { "AF_INET", "AF_INET6", "AF_UNSPEC" };
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  for (int i = 0; i < 3; i++)
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    {
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      struct addrinfo hints =
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        {
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          .ai_socktype = 0,
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          .ai_protocol = 0,
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          .ai_family = family[i],
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          .ai_flags = 0,
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        };
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      struct addrinfo *result;
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      int res = getaddrinfo (host_name, NULL, &hints, &result);
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      if (res != EAI_AGAIN)
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        FAIL_EXIT1 ("getaddrinfo (%s, %s) returned %s, expected EAI_AGAIN",
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                    host_name, family_names[i], gai_strerror (res));
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    }
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}
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/* Simulate DNS server dropping all queries.  */
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static void
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test_drop (void)
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{
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  struct resolv_test *aux = resolv_test_start
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    ((struct resolv_redirect_config)
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     {
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       .response_callback = response_drop,
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     });
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  /* Reduce default timeout to make the test run faster.  */
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  _res.retrans = 1;
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  _res.retry = 1;
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  query_host ("site.example");
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  resolv_test_end (aux);
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}
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/* Simulate DNS server sending zero-length responses.  */
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static void
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test_zero_len_packet (void)
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{
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  struct resolv_test *aux = resolv_test_start
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    ((struct resolv_redirect_config)
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     {
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       .response_callback = response_zero_len,
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     });
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  query_host ("site.example");
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  resolv_test_end (aux);
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}
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static int
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do_test (void)
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{
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  test_drop ();
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  test_zero_len_packet ();
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  if (!response_called_drop)
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    FAIL_EXIT1 ("response_drop callback was not called");
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  if (!response_called_zero_len)
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    FAIL_EXIT1 ("response_zero_len callback was not called");
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  return 0;
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}
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#include <support/test-driver.c>
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