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/* Test __libc_res_nsend buffer mismanagement, basic TCP coverage.
Copyright (C) 2016-2025 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 <errno.h>
#include <netdb.h>
#include <resolv.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <support/check.h>
#include <support/check_nss.h>
#include <support/resolv_test.h>
#include <support/xthread.h>
#include <support/xmemstream.h>
static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
static int initial_address_count = 1;
static int subsequent_address_count = 2000;
static int response_number = 0;
static void
response (const struct resolv_response_context *ctx,
struct resolv_response_builder *b,
const char *qname, uint16_t qclass, uint16_t qtype)
{
TEST_VERIFY_EXIT (qname != NULL);
/* If not using TCP, just force its use. */
if (!ctx->tcp)
{
struct resolv_response_flags flags = {.tc = true};
resolv_response_init (b, flags);
resolv_response_add_question (b, qname, qclass, qtype);
return;
}
struct resolv_response_flags flags = {};
resolv_response_init (b, flags);
resolv_response_add_question (b, qname, qclass, qtype);
resolv_response_section (b, ns_s_an);
/* The number of addresses (in the additional section) for the name
server record (in the authoritative section). */
int address_count;
xpthread_mutex_lock (&lock);
++response_number;
if (response_number == 1)
address_count = initial_address_count;
else if (response_number == 2)
{
address_count = 0;
resolv_response_drop (b);
resolv_response_close (b);
}
else
address_count = subsequent_address_count;
xpthread_mutex_unlock (&lock);
/* Only add the address record to the answer section if we requested
any name server addresses. */
if (address_count > 0)
{
resolv_response_open_record (b, qname, qclass, qtype, 0);
switch (qtype)
{
case T_A:
{
char ipv4[4] = {10, response_number >> 8, response_number, 0};
ipv4[3] = 2 * ctx->tcp + 4 * ctx->server_index;
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,
response_number >> 8, response_number, 0, 0};
ipv6[15] = 2 * ctx->tcp + 4 * ctx->server_index;
resolv_response_add_data (b, &ipv6, sizeof (ipv6));
}
break;
default:
support_record_failure ();
printf ("error: unexpected QTYPE: %s/%u/%u\n",
qname, qclass, qtype);
}
resolv_response_close_record (b);
/* Add the name server record. */
resolv_response_section (b, ns_s_ns);
resolv_response_open_record (b, "example", C_IN, T_NS, 0);
resolv_response_add_name (b, "ns.example");
resolv_response_close_record (b);
/* Increase the response size with name server addresses. These
addresses are not copied out of nss_dns, and thus do not
trigger getaddrinfo retries with a larger buffer, making
testing more predictable. */
resolv_response_section (b, ns_s_ar);
for (int i = 1; i <= address_count; ++i)
{
resolv_response_open_record (b, "ns.example", qclass, qtype, 0);
switch (qtype)
{
case T_A:
{
char ipv4[4] = {response_number, i >> 8, i, 0};
ipv4[3] = 2 * ctx->tcp + 4 * ctx->server_index;
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,
response_number >> 8, response_number,
i >> 8, i, 0, 0};
ipv6[15] = 2 * ctx->tcp + 4 * ctx->server_index;
resolv_response_add_data (b, &ipv6, sizeof (ipv6));
}
break;
default:
support_record_failure ();
printf ("error: unexpected QTYPE: %s/%u/%u\n",
qname, qclass, qtype);
}
resolv_response_close_record (b);
}
}
}
static char *
expected_result (unsigned port, unsigned response_number)
{
struct xmemstream mem;
xopen_memstream (&mem);
/* We fail the second TCP query to the first server by closing the
connection immediately, without returning any data. This should
cause failover to the second server. */
int server_index = 1;
fprintf (mem.out, "address: STREAM/TCP 10.%u.%u.%u %u\n",
(response_number >> 8) & 0xff, response_number & 0xff,
2 + 4 * server_index, port);
fprintf (mem.out, "address: STREAM/TCP 2001:db8::%x:%x %u\n",
(response_number + 1) & 0xffff,
2 + 4 * server_index, port);
xfclose_memstream (&mem);
return mem.buffer;
}
static void
test_different_sizes (void)
{
struct addrinfo hints =
{
.ai_family = AF_UNSPEC,
.ai_socktype = SOCK_STREAM,
.ai_protocol = IPPROTO_TCP,
};
struct addrinfo *ai;
char *expected;
int ret;
/* This magic number produces a response size close to 2048
bytes. */
initial_address_count = 124;
response_number = 0;
ret = getaddrinfo ("www.example", "80", &hints, &ai);
expected = expected_result (80, 3);
check_addrinfo ("www.example:80", ai, ret, expected);
if (ret == 0)
freeaddrinfo (ai);
free (expected);
response_number = 0;
ret = getaddrinfo ("www123.example", "80", &hints, &ai);
if (ret == 0)
freeaddrinfo (ai);
response_number = 0;
ret = getaddrinfo ("www1234.example", "80", &hints, &ai);
if (ret == 0)
freeaddrinfo (ai);
response_number = 0;
ret = getaddrinfo ("www12345.example", "80", &hints, &ai);
if (ret == 0)
freeaddrinfo (ai);
}
static int
do_test (void)
{
struct resolv_test *obj = resolv_test_start
((struct resolv_redirect_config)
{
.response_callback = response
});
test_different_sizes ();
_res.options |= RES_SNGLKUP;
test_different_sizes ();
_res.options |= RES_SNGLKUPREOP;
test_different_sizes ();
resolv_test_end (obj);
return 0;
}
#include <support/test-driver.c>
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