[PATCH v2 01/13] resolv: Add tst-resolv-byaddr for testing reverse lookup
Siddhesh Poyarekar
siddhesh@gotplt.org
Mon Aug 29 19:56:17 GMT 2022
On 2022-08-26 06:33, Florian Weimer via Libc-alpha wrote:
> Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
> ---
> resolv/Makefile | 2 +
> resolv/tst-resolv-byaddr.c | 326 +++++++++++++++++++++++++++
> resolv/tst-resolv-maybe_insert_sig.h | 32 +++
> 3 files changed, 360 insertions(+)
> create mode 100644 resolv/tst-resolv-byaddr.c
> create mode 100644 resolv/tst-resolv-maybe_insert_sig.h
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
since it changed a bit :)
>
> diff --git a/resolv/Makefile b/resolv/Makefile
> index 5b15321f9b..98b10d97a0 100644
> --- a/resolv/Makefile
> +++ b/resolv/Makefile
> @@ -91,6 +91,7 @@ tests += \
> tst-res_hnok \
> tst-resolv-basic \
> tst-resolv-binary \
> + tst-resolv-byaddr \
> tst-resolv-edns \
> tst-resolv-network \
> tst-resolv-noaaaa \
> @@ -260,6 +261,7 @@ $(objpfx)tst-resolv-ai_idn-nolibidn2.out: \
> $(gen-locales) $(objpfx)tst-no-libidn2.so
> $(objpfx)tst-resolv-basic: $(objpfx)libresolv.so $(shared-thread-library)
> $(objpfx)tst-resolv-binary: $(objpfx)libresolv.so $(shared-thread-library)
> +$(objpfx)tst-resolv-byaddr: $(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: $(objpfx)libresolv.so
> diff --git a/resolv/tst-resolv-byaddr.c b/resolv/tst-resolv-byaddr.c
> new file mode 100644
> index 0000000000..6299e89837
> --- /dev/null
> +++ b/resolv/tst-resolv-byaddr.c
> @@ -0,0 +1,326 @@
> +/* Test reverse DNS lookup.
> + Copyright (C) 2022 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 <arpa/inet.h>
> +#include <errno.h>
> +#include <netdb.h>
> +#include <stdbool.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <support/check.h>
> +#include <support/check_nss.h>
> +#include <support/next_to_fault.h>
> +#include <support/resolv_test.h>
> +#include <support/support.h>
> +
> +#include "tst-resolv-maybe_insert_sig.h"
> +
> +/* QNAME format:
> +
> + ADDRESSES.CNAMES...(lots of 0s)...8.b.d.0.1.0.0.2.ip6.arpa.
> + CNAMES|ADDRESSES.2.0.192.in-addr-arpa.
> +
> + For the IPv4 reverse lookup, the address count is in the lower
> + bits.
> +
> + CNAMES is the length of the CNAME chain, ADDRESSES is the number of
> + addresses in the response. The special value 15 means that there
> + are no addresses, and the RCODE is NXDOMAIN. */
> +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_PTR);
> +
> + unsigned int addresses, cnames, bits;
> + char *tail;
> + if (strstr (qname, "ip6.arpa") != NULL
> + && sscanf (qname, "%x.%x.%ms", &addresses, &cnames, &tail) == 3)
> + TEST_COMPARE_STRING (tail, "\
> +0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa");
> + else if (sscanf (qname, "%u.%ms", &bits, &tail) == 2)
> + {
> + TEST_COMPARE_STRING (tail, "2.0.192.in-addr.arpa");
> + addresses = bits & 0x0f;
> + cnames = bits >> 4;
> + }
> + else
> + FAIL_EXIT1 ("invalid QNAME: %s", qname);
> + free (tail);
> +
> + int rcode;
> + if (addresses == 15)
> + {
> + /* Special case: Use no addresses with NXDOMAIN response. */
> + rcode = ns_r_nxdomain;
> + addresses = 0;
> + }
> + else
> + rcode = 0;
> +
> + struct resolv_response_flags flags = { .rcode = rcode };
> + resolv_response_init (b, flags);
> + resolv_response_add_question (b, qname, qclass, qtype);
> + resolv_response_section (b, ns_s_an);
> + maybe_insert_sig (b, qname);
> +
> + /* Provide the requested number of CNAME records. */
> + char *previous_name = (char *) qname;
> + for (int unique = 0; unique < cnames; ++unique)
> + {
> + resolv_response_open_record (b, previous_name, qclass, T_CNAME, 60);
> + char *new_name = xasprintf ("%d.alias.example", unique);
> + resolv_response_add_name (b, new_name);
> + resolv_response_close_record (b);
> +
> + maybe_insert_sig (b, qname);
> +
> + if (previous_name != qname)
> + free (previous_name);
> + previous_name = new_name;
> + }
> +
> + for (int unique = 0; unique < addresses; ++unique)
> + {
> + resolv_response_open_record (b, previous_name, qclass, T_PTR, 60);
> + char *ptr = xasprintf ("unique-%d.cnames-%u.addresses-%u.example",
> + unique, cnames, addresses);
> + resolv_response_add_name (b, ptr);
> + free (ptr);
> + resolv_response_close_record (b);
> + }
> +
> + if (previous_name != qname)
> + free (previous_name);
> +}
> +
> +/* Used to check that gethostbyaddr_r does not write past the buffer
> + end. */
> +static struct support_next_to_fault ntf;
> +
> +/* Perform a gethostbyaddr call and check the result. */
> +static void
> +check_gethostbyaddr (const char *address, const char *expected)
> +{
> + unsigned char bytes[16];
> + unsigned int byteslen;
> + int family;
> + if (strchr (address, ':') != NULL)
> + {
> + family = AF_INET6;
> + byteslen = 16;
> + }
> + else
> + {
> + family = AF_INET;
> + byteslen = 4;
> + }
> + TEST_COMPARE (inet_pton (family, address, bytes), 1);
> +
> + struct hostent *e = gethostbyaddr (bytes, byteslen, family);
> + check_hostent (address, e, expected);
> +
> + if (e == NULL)
> + return;
> +
> + /* Try gethostbyaddr_r with increasing sizes until success. First
> + compute a reasonable minimum buffer size, to avoid many pointless
> + attempts. */
> + size_t minimum_size = strlen (e->h_name);
> + for (int i = 0; e->h_addr_list[i] != NULL; ++i)
> + minimum_size += e->h_length + sizeof (char *);
> + for (int i = 0; e->h_aliases[i] != NULL; ++i)
> + minimum_size += strlen (e->h_aliases[i]) + 1 + sizeof (char *);
> +
> + /* Gradually increase the size until success. */
> + for (size_t size = minimum_size; size < ntf.length; ++size)
> + {
> + struct hostent result;
> + int herrno;
> + int ret = gethostbyaddr_r (bytes, byteslen, family, &result,
> + ntf.buffer + ntf.length - size, size,
> + &e, &herrno);
> + if (ret == ERANGE)
> + /* Retry with larger size. */
> + TEST_COMPARE (herrno, NETDB_INTERNAL);
> + else if (ret == 0)
> + {
> + TEST_VERIFY (size > minimum_size);
> + check_hostent (address, e, expected);
> + return;
> + }
> + else
> + FAIL_EXIT1 ("Unexpected gethostbyaddr_r failure: %d", ret);
> + }
> +
> + FAIL_EXIT1 ("gethostbyaddr_r always failed for: %s", address);
> +}
> +
> +/* Perform a getnameinfo call and check the result. */
> +static void
> +check_getnameinfo (const char *address, const char *expected)
> +{
> + struct sockaddr_in sin = { };
> + struct sockaddr_in6 sin6 = { };
> + void *sa;
> + socklen_t salen;
> + if (strchr (address, ':') != NULL)
> + {
> + sin6.sin6_family = AF_INET6;
> + TEST_COMPARE (inet_pton (AF_INET6, address, &sin6.sin6_addr), 1);
> + sin6.sin6_port = htons (80);
> + sa = &sin6;
> + salen = sizeof (sin6);
> + }
> + else
> + {
> + sin.sin_family = AF_INET;
> + TEST_COMPARE (inet_pton (AF_INET, address, &sin.sin_addr), 1);
> + sin.sin_port = htons (80);
> + sa = &sin;
> + salen = sizeof (sin);
> + }
> +
> + char host[64];
> + char service[64];
> + int ret = getnameinfo (sa, salen, host,
> + sizeof (host), service, sizeof (service),
> + NI_NAMEREQD | NI_NUMERICSERV);
> + switch (ret)
> + {
> + case 0:
> + TEST_COMPARE_STRING (host, expected);
> + TEST_COMPARE_STRING (service, "80");
> + break;
> + case EAI_SYSTEM:
> + TEST_COMPARE_STRING (strerror (errno), expected);
> + break;
> + default:
> + TEST_COMPARE_STRING (gai_strerror (ret), expected);
> + }
> +}
> +
> +static int
> +do_test (void)
> +{
> + /* Some reasonably upper bound for the maximum response size. */
> + ntf = support_next_to_fault_allocate (4096);
> +
> + struct resolv_test *obj = resolv_test_start
> + ((struct resolv_redirect_config)
> + {
> + .response_callback = response
> + });
> +
> + for (int do_insert_sig = 0; do_insert_sig < 2; ++do_insert_sig)
> + {
> + insert_sig = do_insert_sig;
> +
> + /* No PTR record, RCODE=0. */
> + check_gethostbyaddr ("192.0.2.0", "error: NO_RECOVERY\n");
> + check_getnameinfo ("192.0.2.0", "Name or service not known");
> + check_gethostbyaddr ("192.0.2.16", "error: NO_RECOVERY\n");
> + check_getnameinfo ("192.0.2.16", "Name or service not known");
> + check_gethostbyaddr ("192.0.2.32", "error: NO_RECOVERY\n");
> + check_getnameinfo ("192.0.2.32", "Name or service not known");
> + check_gethostbyaddr ("2001:db8::", "error: NO_RECOVERY\n");
> + check_getnameinfo ("2001:db8::", "Name or service not known");
> + check_gethostbyaddr ("2001:db8::10", "error: NO_RECOVERY\n");
> + check_getnameinfo ("2001:db8::10", "Name or service not known");
> + check_gethostbyaddr ("2001:db8::20", "error: NO_RECOVERY\n");
> + check_getnameinfo ("2001:db8::20", "Name or service not known");
> +
> + /* No PTR record, NXDOMAIN. */
> + check_gethostbyaddr ("192.0.2.15", "error: HOST_NOT_FOUND\n");
> + check_getnameinfo ("192.0.2.15", "Name or service not known");
> + check_gethostbyaddr ("192.0.2.31", "error: HOST_NOT_FOUND\n");
> + check_getnameinfo ("192.0.2.31", "Name or service not known");
> + check_gethostbyaddr ("192.0.2.47", "error: HOST_NOT_FOUND\n");
> + check_getnameinfo ("192.0.2.47", "Name or service not known");
> + check_gethostbyaddr ("2001:db8::f", "error: HOST_NOT_FOUND\n");
> + check_getnameinfo ("2001:db8::f", "Name or service not known");
> + check_gethostbyaddr ("2001:db8::1f", "error: HOST_NOT_FOUND\n");
> + check_getnameinfo ("2001:db8::1f", "Name or service not known");
> + check_gethostbyaddr ("2001:db8::2f", "error: HOST_NOT_FOUND\n");
> + check_getnameinfo ("2001:db8::2f", "Name or service not known");
> +
> + /* Actual response data. Only the first PTR record is returned. */
> + check_gethostbyaddr ("192.0.2.1",
> + "name: unique-0.cnames-0.addresses-1.example\n"
> + "address: 192.0.2.1\n");
> + check_getnameinfo ("192.0.2.1",
> + "unique-0.cnames-0.addresses-1.example");
> + check_gethostbyaddr ("192.0.2.17",
> + "name: unique-0.cnames-1.addresses-1.example\n"
> + "address: 192.0.2.17\n");
> + check_getnameinfo ("192.0.2.17",
> + "unique-0.cnames-1.addresses-1.example");
> + check_gethostbyaddr ("192.0.2.18",
> + "name: unique-0.cnames-1.addresses-2.example\n"
> + "address: 192.0.2.18\n");
> + check_getnameinfo ("192.0.2.18",
> + "unique-0.cnames-1.addresses-2.example");
> + check_gethostbyaddr ("192.0.2.33",
> + "name: unique-0.cnames-2.addresses-1.example\n"
> + "address: 192.0.2.33\n");
> + check_getnameinfo ("192.0.2.33",
> + "unique-0.cnames-2.addresses-1.example");
> + check_gethostbyaddr ("192.0.2.34",
> + "name: unique-0.cnames-2.addresses-2.example\n"
> + "address: 192.0.2.34\n");
> + check_getnameinfo ("192.0.2.34",
> + "unique-0.cnames-2.addresses-2.example");
> +
> + /* Same for IPv6 addresses. */
> + check_gethostbyaddr ("2001:db8::1",
> + "name: unique-0.cnames-0.addresses-1.example\n"
> + "address: 2001:db8::1\n");
> + check_getnameinfo ("2001:db8::1",
> + "unique-0.cnames-0.addresses-1.example");
> + check_gethostbyaddr ("2001:db8::11",
> + "name: unique-0.cnames-1.addresses-1.example\n"
> + "address: 2001:db8::11\n");
> + check_getnameinfo ("2001:db8::11",
> + "unique-0.cnames-1.addresses-1.example");
> + check_gethostbyaddr ("2001:db8::12",
> + "name: unique-0.cnames-1.addresses-2.example\n"
> + "address: 2001:db8::12\n");
> + check_getnameinfo ("2001:db8::12",
> + "unique-0.cnames-1.addresses-2.example");
> + check_gethostbyaddr ("2001:db8::21",
> + "name: unique-0.cnames-2.addresses-1.example\n"
> + "address: 2001:db8::21\n");
> + check_getnameinfo ("2001:db8::21",
> + "unique-0.cnames-2.addresses-1.example");
> + check_gethostbyaddr ("2001:db8::22",
> + "name: unique-0.cnames-2.addresses-2.example\n"
> + "address: 2001:db8::22\n");
> + check_getnameinfo ("2001:db8::22",
> + "unique-0.cnames-2.addresses-2.example");
> + }
> +
> + resolv_test_end (obj);
> +
> + support_next_to_fault_free (&ntf);
> + return 0;
> +}
> +
> +#include <support/test-driver.c>
> diff --git a/resolv/tst-resolv-maybe_insert_sig.h b/resolv/tst-resolv-maybe_insert_sig.h
> new file mode 100644
> index 0000000000..05725225af
> --- /dev/null
> +++ b/resolv/tst-resolv-maybe_insert_sig.h
> @@ -0,0 +1,32 @@
> +/* Code snippet for optionally inserting ignored SIG records in resolver tests.
> + Copyright (C) 2022 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/>. */
> +
> +/* Set to true for an alternative pass that inserts (ignored) SIG
> + records. This does not alter the response, so this property is not
> + encoded in the QNAME. The variable needs to be volatile because
> + leaf attributes tell GCC that the response function is not
> + called. */
> +static volatile bool insert_sig;
> +
> +static void
> +maybe_insert_sig (struct resolv_response_builder *b, const char *owner)
> +{
> + resolv_response_open_record (b, owner, C_IN, T_SIG, 60);
> + resolv_response_add_data (b, "", 1);
> + resolv_response_close_record (b);
> +}
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