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533 lines
16 KiB
C
533 lines
16 KiB
C
/* Test EDNS handling in the stub resolver.
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Copyright (C) 2016-2020 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 <errno.h>
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#include <netdb.h>
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#include <resolv.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <support/check.h>
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#include <support/resolv_test.h>
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#include <support/support.h>
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#include <support/test-driver.h>
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#include <support/xthread.h>
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/* Data produced by a test query. */
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struct response_data
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{
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char *qname;
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uint16_t qtype;
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struct resolv_edns_info edns;
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};
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/* Global array used by put_response and get_response to record
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response data. The test DNS server returns the index of the array
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element which contains the actual response data. This enables the
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test case to return arbitrary amounts of data with the limited
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number of bits which fit into an IP addres.
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The volatile specifier is needed because the test case accesses
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these variables from a callback function called from a function
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which is marked as __THROW (i.e., a leaf function which actually is
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not). */
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static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
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static struct response_data ** volatile response_data_array;
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volatile static size_t response_data_count;
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/* Extract information from the query, store it in a struct
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response_data object, and return its index in the
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response_data_array. */
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static unsigned int
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put_response (const struct resolv_response_context *ctx,
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const char *qname, uint16_t qtype)
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{
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xpthread_mutex_lock (&mutex);
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++response_data_count;
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/* We only can represent 2**24 indexes in 10.0.0.0/8. */
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TEST_VERIFY (response_data_count < (1 << 24));
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response_data_array = xrealloc
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(response_data_array, sizeof (*response_data_array) * response_data_count);
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unsigned int index = response_data_count - 1;
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struct response_data *data = xmalloc (sizeof (*data));
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*data = (struct response_data)
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{
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.qname = xstrdup (qname),
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.qtype = qtype,
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.edns = ctx->edns,
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};
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response_data_array[index] = data;
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xpthread_mutex_unlock (&mutex);
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return index;
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}
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/* Verify the index into the response_data array and return the data
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at it. */
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static struct response_data *
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get_response (unsigned int index)
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{
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xpthread_mutex_lock (&mutex);
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TEST_VERIFY_EXIT (index < response_data_count);
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struct response_data *result = response_data_array[index];
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xpthread_mutex_unlock (&mutex);
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return result;
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}
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/* Deallocate all response data. */
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static void
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free_response_data (void)
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{
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xpthread_mutex_lock (&mutex);
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size_t count = response_data_count;
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struct response_data **array = response_data_array;
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for (unsigned int i = 0; i < count; ++i)
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{
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struct response_data *data = array[i];
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free (data->qname);
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free (data);
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}
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free (array);
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response_data_array = NULL;
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response_data_count = 0;
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xpthread_mutex_unlock (&mutex);
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}
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#define EDNS_PROBE_EXAMPLE "edns-probe.example"
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static void
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response (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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TEST_VERIFY_EXIT (qname != NULL);
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const char *qname_compare = qname;
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/* The "formerr." prefix can be used to request a FORMERR response on the
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first server. */
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bool send_formerr;
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if (strncmp ("formerr.", qname, strlen ("formerr.")) == 0)
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{
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send_formerr = true;
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qname_compare = qname + strlen ("formerr.");
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}
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else
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{
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send_formerr = false;
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qname_compare = qname;
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}
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/* The "tcp." prefix can be used to request TCP fallback. */
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bool force_tcp;
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if (strncmp ("tcp.", qname_compare, strlen ("tcp.")) == 0)
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{
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force_tcp = true;
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qname_compare += strlen ("tcp.");
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}
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else
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force_tcp = false;
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enum {edns_probe} requested_qname;
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if (strcmp (qname_compare, EDNS_PROBE_EXAMPLE) == 0)
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requested_qname = edns_probe;
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else
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{
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support_record_failure ();
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printf ("error: unexpected QNAME: %s (reduced: %s)\n",
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qname, qname_compare);
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return;
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}
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TEST_VERIFY_EXIT (qclass == C_IN);
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struct resolv_response_flags flags = { };
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flags.tc = force_tcp && !ctx->tcp;
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if (!flags.tc && send_formerr && ctx->server_index == 0)
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/* Send a FORMERR for the first full response from the first
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server. */
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flags.rcode = 1; /* FORMERR */
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resolv_response_init (b, flags);
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resolv_response_add_question (b, qname, qclass, qtype);
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if (flags.tc || flags.rcode != 0)
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return;
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if (test_verbose)
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printf ("info: edns=%d payload_size=%d\n",
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ctx->edns.active, ctx->edns.payload_size);
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/* Encode the response_data object in multiple address records.
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Each record carries two bytes of payload data, and an index. */
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resolv_response_section (b, ns_s_an);
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switch (requested_qname)
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{
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case edns_probe:
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{
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unsigned int index = put_response (ctx, qname, qtype);
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switch (qtype)
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{
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case T_A:
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{
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uint32_t addr = htonl (0x0a000000 | index);
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resolv_response_open_record (b, qname, qclass, qtype, 0);
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resolv_response_add_data (b, &addr, sizeof (addr));
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resolv_response_close_record (b);
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}
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break;
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case T_AAAA:
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{
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char addr[16]
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= {0x20, 0x01, 0xd, 0xb8, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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index >> 16, index >> 8, index};
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resolv_response_open_record (b, qname, qclass, qtype, 0);
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resolv_response_add_data (b, &addr, sizeof (addr));
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resolv_response_close_record (b);
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}
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}
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}
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break;
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}
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}
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/* Update *DATA with data from ADDRESS of SIZE. Set the corresponding
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flag in SHADOW for each byte written. */
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static struct response_data *
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decode_address (const void *address, size_t size)
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{
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switch (size)
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{
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case 4:
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TEST_VERIFY (memcmp (address, "\x0a", 1) == 0);
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break;
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case 16:
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TEST_VERIFY (memcmp (address, "\x20\x01\x0d\xb8", 4) == 0);
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break;
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default:
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FAIL_EXIT1 ("unexpected address size %zu", size);
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}
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const unsigned char *addr = address;
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unsigned int index = addr[size - 3] * 256 * 256
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+ addr[size - 2] * 256
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+ addr[size - 1];
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return get_response (index);
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}
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static struct response_data *
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decode_hostent (struct hostent *e)
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{
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TEST_VERIFY_EXIT (e != NULL);
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TEST_VERIFY_EXIT (e->h_addr_list[0] != NULL);
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TEST_VERIFY (e->h_addr_list[1] == NULL);
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return decode_address (e->h_addr_list[0], e->h_length);
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}
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static struct response_data *
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decode_addrinfo (struct addrinfo *ai, int family)
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{
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struct response_data *data = NULL;
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while (ai != NULL)
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{
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if (ai->ai_family == family)
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{
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struct response_data *new_data;
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switch (family)
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{
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case AF_INET:
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{
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struct sockaddr_in *pin = (struct sockaddr_in *) ai->ai_addr;
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new_data = decode_address (&pin->sin_addr.s_addr, 4);
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}
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break;
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case AF_INET6:
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{
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struct sockaddr_in6 *pin = (struct sockaddr_in6 *) ai->ai_addr;
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new_data = decode_address (&pin->sin6_addr.s6_addr, 16);
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}
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break;
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default:
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FAIL_EXIT1 ("invalid address family %d", ai->ai_family);
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}
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if (data == NULL)
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data = new_data;
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else
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/* Check pointer equality because this should be the same
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response (same index). */
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TEST_VERIFY (data == new_data);
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}
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ai = ai->ai_next;
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}
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TEST_VERIFY_EXIT (data != NULL);
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return data;
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}
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/* Updated by the main test loop in accordance with what is set in
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_res.options. */
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static bool use_edns;
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static bool use_dnssec;
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/* Verify the decoded response data against the flags above. */
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static void
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verify_response_data_payload (struct response_data *data,
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size_t expected_payload)
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{
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bool edns = use_edns || use_dnssec;
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TEST_VERIFY (data->edns.active == edns);
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if (!edns)
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expected_payload = 0;
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if (data->edns.payload_size != expected_payload)
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{
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support_record_failure ();
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printf ("error: unexpected payload size %d (edns=%d)\n",
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(int) data->edns.payload_size, edns);
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}
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uint16_t expected_flags = 0;
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if (use_dnssec)
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expected_flags |= 0x8000; /* DO flag. */
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if (data->edns.flags != expected_flags)
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{
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support_record_failure ();
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printf ("error: unexpected EDNS flags 0x%04x (edns=%d)\n",
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(int) data->edns.flags, edns);
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}
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}
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/* Same as verify_response_data_payload, but use the default
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payload. */
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static void
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verify_response_data (struct response_data *data)
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{
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verify_response_data_payload (data, 1200);
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}
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static void
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check_hostent (struct hostent *e)
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{
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TEST_VERIFY_EXIT (e != NULL);
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verify_response_data (decode_hostent (e));
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}
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static void
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do_ai (int family)
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{
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struct addrinfo hints = { .ai_family = family };
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struct addrinfo *ai;
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int ret = getaddrinfo (EDNS_PROBE_EXAMPLE, "80", &hints, &ai);
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TEST_VERIFY_EXIT (ret == 0);
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switch (family)
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{
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case AF_INET:
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case AF_INET6:
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verify_response_data (decode_addrinfo (ai, family));
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break;
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case AF_UNSPEC:
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verify_response_data (decode_addrinfo (ai, AF_INET));
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verify_response_data (decode_addrinfo (ai, AF_INET6));
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break;
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default:
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FAIL_EXIT1 ("invalid address family %d", family);
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}
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freeaddrinfo (ai);
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}
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enum res_op
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{
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res_op_search,
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res_op_query,
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res_op_querydomain,
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res_op_nsearch,
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res_op_nquery,
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res_op_nquerydomain,
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res_op_last = res_op_nquerydomain,
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};
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static const char *
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res_op_string (enum res_op op)
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{
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switch (op)
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{
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case res_op_search:
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return "res_search";
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case res_op_query:
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return "res_query";
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case res_op_querydomain:
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return "res_querydomain";
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case res_op_nsearch:
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return "res_nsearch";
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case res_op_nquery:
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return "res_nquery";
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case res_op_nquerydomain:
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return "res_nquerydomain";
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}
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FAIL_EXIT1 ("invalid res_op value %d", (int) op);
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}
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/* Call libresolv function OP to look up PROBE_NAME, with an answer
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buffer of SIZE bytes. Check that the advertised UDP buffer size is
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in fact EXPECTED_BUFFER_SIZE. */
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static void
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do_res_search (const char *probe_name, enum res_op op, size_t size,
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size_t expected_buffer_size)
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{
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if (test_verbose)
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printf ("info: testing %s with buffer size %zu\n",
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res_op_string (op), size);
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unsigned char *buffer = xmalloc (size);
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int ret = -1;
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switch (op)
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{
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case res_op_search:
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ret = res_search (probe_name, C_IN, T_A, buffer, size);
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break;
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case res_op_query:
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ret = res_query (probe_name, C_IN, T_A, buffer, size);
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break;
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case res_op_nsearch:
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ret = res_nsearch (&_res, probe_name, C_IN, T_A, buffer, size);
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break;
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case res_op_nquery:
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ret = res_nquery (&_res, probe_name, C_IN, T_A, buffer, size);
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break;
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case res_op_querydomain:
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case res_op_nquerydomain:
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{
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char *example_stripped = xstrdup (probe_name);
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char *dot_example = strstr (example_stripped, ".example");
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if (dot_example != NULL && strcmp (dot_example, ".example") == 0)
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{
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/* Truncate the domain name. */
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*dot_example = '\0';
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if (op == res_op_querydomain)
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ret = res_querydomain
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(example_stripped, "example", C_IN, T_A, buffer, size);
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else
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ret = res_nquerydomain
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(&_res, example_stripped, "example", C_IN, T_A, buffer, size);
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}
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else
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FAIL_EXIT1 ("invalid probe name: %s", probe_name);
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free (example_stripped);
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}
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break;
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}
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TEST_VERIFY_EXIT (ret > 12);
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unsigned char *end = buffer + ret;
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HEADER *hd = (HEADER *) buffer;
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TEST_VERIFY (ntohs (hd->qdcount) == 1);
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TEST_VERIFY (ntohs (hd->ancount) == 1);
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/* Skip over the header. */
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unsigned char *p = buffer + sizeof (*hd);
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/* Skip over the question. */
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ret = dn_skipname (p, end);
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TEST_VERIFY_EXIT (ret > 0);
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p += ret;
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TEST_VERIFY_EXIT (end - p >= 4);
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p += 4;
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/* Skip over the RNAME and the RR header, but stop at the RDATA
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length. */
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ret = dn_skipname (p, end);
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TEST_VERIFY_EXIT (ret > 0);
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p += ret;
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TEST_VERIFY_EXIT (end - p >= 2 + 2 + 4 + 2 + 4);
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p += 2 + 2 + 4;
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/* The IP address should be 4 bytes long. */
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TEST_VERIFY_EXIT (p[0] == 0);
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TEST_VERIFY_EXIT (p[1] == 4);
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/* Extract the address information. */
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p += 2;
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struct response_data *data = decode_address (p, 4);
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verify_response_data_payload (data, expected_buffer_size);
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free (buffer);
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}
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static void
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run_test (const char *probe_name)
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{
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if (test_verbose)
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printf ("\ninfo: * use_edns=%d use_dnssec=%d\n",
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use_edns, use_dnssec);
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check_hostent (gethostbyname (probe_name));
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check_hostent (gethostbyname2 (probe_name, AF_INET));
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check_hostent (gethostbyname2 (probe_name, AF_INET6));
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do_ai (AF_UNSPEC);
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do_ai (AF_INET);
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do_ai (AF_INET6);
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for (int op = 0; op <= res_op_last; ++op)
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{
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do_res_search (probe_name, op, 301, 512);
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do_res_search (probe_name, op, 511, 512);
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do_res_search (probe_name, op, 512, 512);
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do_res_search (probe_name, op, 513, 513);
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do_res_search (probe_name, op, 657, 657);
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do_res_search (probe_name, op, 1199, 1199);
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do_res_search (probe_name, op, 1200, 1200);
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do_res_search (probe_name, op, 1201, 1200);
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do_res_search (probe_name, op, 65535, 1200);
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}
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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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for (int do_edns = 0; do_edns < 2; ++do_edns)
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for (int do_dnssec = 0; do_dnssec < 2; ++do_dnssec)
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for (int do_tcp = 0; do_tcp < 2; ++do_tcp)
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for (int do_formerr = 0; do_formerr < 2; ++do_formerr)
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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,
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});
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use_edns = do_edns;
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if (do_edns)
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_res.options |= RES_USE_EDNS0;
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use_dnssec = do_dnssec;
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if (do_dnssec)
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_res.options |= RES_USE_DNSSEC;
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|
|
|
char *probe_name = xstrdup (EDNS_PROBE_EXAMPLE);
|
|
if (do_tcp)
|
|
{
|
|
char *n = xasprintf ("tcp.%s", probe_name);
|
|
free (probe_name);
|
|
probe_name = n;
|
|
}
|
|
if (do_formerr)
|
|
{
|
|
/* Send a garbage query in an attempt to trigger EDNS
|
|
fallback. */
|
|
char *n = xasprintf ("formerr.%s", probe_name);
|
|
gethostbyname (n);
|
|
free (n);
|
|
}
|
|
|
|
run_test (probe_name);
|
|
|
|
free (probe_name);
|
|
resolv_test_end (aux);
|
|
}
|
|
|
|
free_response_data ();
|
|
return 0;
|
|
}
|
|
|
|
#include <support/test-driver.c>
|