/* Test parallel queries with transaction ID collisions. Copyright (C) 2020-2022 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 . */ #include #include #include #include #include #include #include #include #include #include #include #include /* Result of parsing a DNS question name. A question name has the form reorder-N-M-rcode-C.example.net, where N and M are either 0 and 1, corresponding to the reorder member, and C is a number that will be stored in the rcode field. Also see parse_qname below. */ struct parsed_qname { /* The DNS response code requested from the first server. The second server always responds with RCODE zero. */ int rcode; /* Indicates whether to perform reordering in the responses from the respective server. */ bool reorder[2]; }; /* Fills *PARSED based on QNAME. */ static void parse_qname (struct parsed_qname *parsed, const char *qname) { int reorder0; int reorder1; int rcode; char *suffix; if (sscanf (qname, "reorder-%d-%d.rcode-%d.%ms", &reorder0, &reorder1, &rcode, &suffix) == 4) { if (reorder0 != 0) TEST_COMPARE (reorder0, 1); if (reorder1 != 0) TEST_COMPARE (reorder1, 1); TEST_VERIFY (rcode >= 0 && rcode <= 15); TEST_COMPARE_STRING (suffix, "example.net"); free (suffix); parsed->rcode = rcode; parsed->reorder[0] = reorder0; parsed->reorder[1] = reorder1; } else FAIL_EXIT1 ("unexpected query: %s", qname); } /* Used to construct a response. The first server responds with an error, the second server succeeds. */ static void build_response (const struct resolv_response_context *ctx, struct resolv_response_builder *b, const char *qname, uint16_t qclass, uint16_t qtype) { struct parsed_qname parsed; parse_qname (&parsed, qname); switch (ctx->server_index) { case 0: { struct resolv_response_flags flags = { 0 }; if (parsed.rcode == 0) /* Simulate a delegation in case a NODATA (RCODE zero) response is requested. */ flags.clear_ra = true; else flags.rcode = parsed.rcode; resolv_response_init (b, flags); resolv_response_add_question (b, qname, qclass, qtype); } break; case 1: { struct resolv_response_flags flags = { 0, }; resolv_response_init (b, 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); if (qtype == T_A) { char ipv4[4] = { 192, 0, 2, 1 }; resolv_response_add_data (b, &ipv4, sizeof (ipv4)); } else { 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)); } resolv_response_close_record (b); } break; } } /* Used to reorder responses. */ struct resolv_response_context *previous_query; /* Used to keep track of the queries received. */ static int previous_server_index = -1; static uint16_t previous_qtype; /* For each server, buffer the first query and then send both answers to the second query, reordered if requested. */ 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 (qtype == T_A || qtype == T_AAAA); if (ctx->server_index != 0) TEST_COMPARE (ctx->server_index, 1); struct parsed_qname parsed; parse_qname (&parsed, qname); if (previous_query == NULL) { /* No buffered query. Record this query and do not send a response. */ TEST_COMPARE (previous_qtype, 0); previous_query = resolv_response_context_duplicate (ctx); previous_qtype = qtype; resolv_response_drop (b); previous_server_index = ctx->server_index; if (test_verbose) printf ("info: buffering first query for: %s\n", qname); } else { TEST_VERIFY (previous_query != 0); TEST_COMPARE (ctx->server_index, previous_server_index); TEST_VERIFY (previous_qtype != qtype); /* Not a duplicate. */ /* If reordering, send a response for this query explicitly, and then skip the implicit send. */ if (parsed.reorder[ctx->server_index]) { if (test_verbose) printf ("info: sending reordered second response for: %s\n", qname); build_response (ctx, b, qname, qclass, qtype); resolv_response_send_udp (ctx, b); resolv_response_drop (b); } /* Build a response for the previous query and send it, thus reordering the two responses. */ { if (test_verbose) printf ("info: sending first response for: %s\n", qname); struct resolv_response_builder *btmp = resolv_response_builder_allocate (previous_query->query_buffer, previous_query->query_length); build_response (ctx, btmp, qname, qclass, previous_qtype); resolv_response_send_udp (ctx, btmp); resolv_response_builder_free (btmp); } /* If not reordering, send the reply as usual. */ if (!parsed.reorder[ctx->server_index]) { if (test_verbose) printf ("info: sending non-reordered second response for: %s\n", qname); build_response (ctx, b, qname, qclass, qtype); } /* Unbuffer the response and prepare for the next query. */ resolv_response_context_free (previous_query); previous_query = NULL; previous_qtype = 0; previous_server_index = -1; } } /* Runs a query for QNAME and checks for the expected reply. See struct parsed_qname for the expected format for QNAME. */ static void test_qname (const char *qname, int rcode) { struct resolv_context *ctx = __resolv_context_get (); TEST_VERIFY_EXIT (ctx != NULL); unsigned char q1[512]; int q1len = res_mkquery (QUERY, qname, C_IN, T_A, NULL, 0, NULL, q1, sizeof (q1)); TEST_VERIFY_EXIT (q1len > 12); unsigned char q2[512]; int q2len = res_mkquery (QUERY, qname, C_IN, T_AAAA, NULL, 0, NULL, q2, sizeof (q2)); TEST_VERIFY_EXIT (q2len > 12); /* Produce a transaction ID collision. */ memcpy (q2, q1, 2); unsigned char ans1[512]; unsigned char *ans1p = ans1; unsigned char *ans2p = NULL; int nans2p = 0; int resplen2 = 0; int ans2p_malloced = 0; /* Perform a parallel A/AAAA query. */ int resplen1 = __res_context_send (ctx, q1, q1len, q2, q2len, ans1, sizeof (ans1), &ans1p, &ans2p, &nans2p, &resplen2, &ans2p_malloced); TEST_VERIFY (resplen1 > 12); TEST_VERIFY (resplen2 > 12); if (resplen1 <= 12 || resplen2 <= 12) return; if (rcode == 1 || rcode == 3) { /* Format Error and Name Error responses does not trigger switching to the next server. */ TEST_COMPARE (ans1p[3] & 0x0f, rcode); TEST_COMPARE (ans2p[3] & 0x0f, rcode); return; } /* The response should be successful. */ TEST_COMPARE (ans1p[3] & 0x0f, 0); TEST_COMPARE (ans2p[3] & 0x0f, 0); /* Due to bug 19691, the answer may not be in the slot matching the query. Assume that the AAAA response is the longer one. */ unsigned char *a_answer; int a_answer_length; unsigned char *aaaa_answer; int aaaa_answer_length; if (resplen2 > resplen1) { a_answer = ans1p; a_answer_length = resplen1; aaaa_answer = ans2p; aaaa_answer_length = resplen2; } else { a_answer = ans2p; a_answer_length = resplen2; aaaa_answer = ans1p; aaaa_answer_length = resplen1; } { char *expected = xasprintf ("name: %s\n" "address: 192.0.2.1\n", qname); check_dns_packet (qname, a_answer, a_answer_length, expected); free (expected); } { char *expected = xasprintf ("name: %s\n" "address: 2001:db8::1\n", qname); check_dns_packet (qname, aaaa_answer, aaaa_answer_length, expected); free (expected); } if (ans2p_malloced) free (ans2p); __resolv_context_put (ctx); } static int do_test (void) { struct resolv_test *aux = resolv_test_start ((struct resolv_redirect_config) { .response_callback = response, /* The response callback use global state (the previous_* variables), and query processing must therefore be serialized. */ .single_thread_udp = true, }); for (int rcode = 0; rcode <= 5; ++rcode) for (int do_reorder_0 = 0; do_reorder_0 < 2; ++do_reorder_0) for (int do_reorder_1 = 0; do_reorder_1 < 2; ++do_reorder_1) { char *qname = xasprintf ("reorder-%d-%d.rcode-%d.example.net", do_reorder_0, do_reorder_1, rcode); test_qname (qname, rcode); free (qname); } resolv_test_end (aux); return 0; } #include