| /* DNS test framework and libresolv redirection. |
| Copyright (C) 2016-2018 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 |
| <http://www.gnu.org/licenses/>. */ |
| |
| #ifndef SUPPORT_RESOLV_TEST_H |
| #define SUPPORT_RESOLV_TEST_H |
| |
| #include <arpa/nameser.h> |
| #include <stdbool.h> |
| #include <sys/cdefs.h> |
| |
| __BEGIN_DECLS |
| |
| /* Information about EDNS properties of a DNS query. */ |
| struct resolv_edns_info |
| { |
| bool active; |
| uint8_t extended_rcode; |
| uint8_t version; |
| uint16_t flags; |
| uint16_t payload_size; |
| }; |
| |
| /* This struct provides context information when the response callback |
| specified in struct resolv_redirect_config is invoked. */ |
| struct resolv_response_context |
| { |
| const unsigned char *query_buffer; |
| size_t query_length; |
| int server_index; |
| bool tcp; |
| struct resolv_edns_info edns; |
| }; |
| |
| /* This opaque struct is used to construct responses from within the |
| response callback function. */ |
| struct resolv_response_builder; |
| |
| /* This opaque struct collects information about the resolver testing |
| currently in progress. */ |
| struct resolv_test; |
| |
| enum |
| { |
| /* Maximum number of test servers supported by the framework. */ |
| resolv_max_test_servers = 3, |
| }; |
| |
| /* Configuration settings specific to individual test servers. */ |
| struct resolv_redirect_server_config |
| { |
| bool disable_tcp; /* If true, no TCP server is listening. */ |
| bool disable_udp; /* If true, no UDP server is listening. */ |
| }; |
| |
| /* Instructions for setting up the libresolv redirection. */ |
| struct resolv_redirect_config |
| { |
| /* The response_callback function is called for every incoming DNS |
| packet, over UDP or TCP. It must be specified, the other |
| configuration settings are optional. */ |
| void (*response_callback) (const struct resolv_response_context *, |
| struct resolv_response_builder *, |
| const char *qname, |
| uint16_t qclass, uint16_t qtype); |
| |
| /* Per-server configuration. */ |
| struct resolv_redirect_server_config servers[resolv_max_test_servers]; |
| |
| /* Search path entries. The first entry serves as the default |
| domain name as well. */ |
| const char *search[7]; |
| |
| /* Number of servers to activate in resolv. 0 means the default, |
| resolv_max_test_servers. */ |
| int nscount; |
| |
| /* If true, use a single thread to process all UDP queries. This |
| may results in more predictable ordering of queries and |
| responses. */ |
| bool single_thread_udp; |
| |
| /* Do not rewrite the _res variable or change NSS defaults. Use |
| server_address_overrides below to tell the testing framework on |
| which addresses to create the servers. */ |
| bool disable_redirect; |
| |
| /* Use these addresses for creating the DNS servers. The array must |
| have ns_count (or resolv_max_test_servers) sockaddr * elements if |
| not NULL. */ |
| const struct sockaddr *const *server_address_overrides; |
| }; |
| |
| /* Configure NSS to use, nss_dns only for aplicable databases, and try |
| to put the process into a network namespace for better isolation. |
| This may have to be called before resolv_test_start, before the |
| process creates any threads. Otherwise, initialization is |
| performed by resolv_test_start implicitly. */ |
| void resolv_test_init (void); |
| |
| /* Initiate resolver testing. This updates the _res variable as |
| needed. As a side effect, NSS is reconfigured to use nss_dns only |
| for aplicable databases, and the process may enter a network |
| namespace for better isolation. */ |
| struct resolv_test *resolv_test_start (struct resolv_redirect_config); |
| |
| /* Call this function at the end of resolver testing, to free |
| resources and report pending errors (if any). */ |
| void resolv_test_end (struct resolv_test *); |
| |
| /* The remaining facilities in this file are used for constructing |
| response packets from the response_callback function. */ |
| |
| /* Special settings for constructing responses from the callback. */ |
| struct resolv_response_flags |
| { |
| /* 4-bit response code to incorporate into the response. */ |
| unsigned char rcode; |
| |
| /* If true, the TC (truncation) flag will be set. */ |
| bool tc; |
| |
| /* Initial section count values. Can be used to artificially |
| increase the counts, for malformed packet testing.*/ |
| unsigned short qdcount; |
| unsigned short ancount; |
| unsigned short nscount; |
| unsigned short adcount; |
| }; |
| |
| /* Begin a new response with the requested flags. Must be called |
| first. */ |
| void resolv_response_init (struct resolv_response_builder *, |
| struct resolv_response_flags); |
| |
| /* Switches to the section in the response packet. Only forward |
| movement is supported. */ |
| void resolv_response_section (struct resolv_response_builder *, ns_sect); |
| |
| /* Add a question record to the question section. */ |
| void resolv_response_add_question (struct resolv_response_builder *, |
| const char *name, uint16_t class, |
| uint16_t type); |
| /* Starts a new resource record with the specified owner name, class, |
| type, and TTL. Data is supplied with resolv_response_add_data or |
| resolv_response_add_name. */ |
| void resolv_response_open_record (struct resolv_response_builder *, |
| const char *name, uint16_t class, |
| uint16_t type, uint32_t ttl); |
| |
| /* Add unstructed bytes to the RDATA part of a resource record. */ |
| void resolv_response_add_data (struct resolv_response_builder *, |
| const void *, size_t); |
| |
| /* Add a compressed domain name to the RDATA part of a resource |
| record. */ |
| void resolv_response_add_name (struct resolv_response_builder *, |
| const char *name); |
| |
| /* Mark the end of the constructed record. Must be called last. */ |
| void resolv_response_close_record (struct resolv_response_builder *); |
| |
| /* Drop this query packet (that is, do not send a response, not even |
| an empty packet). */ |
| void resolv_response_drop (struct resolv_response_builder *); |
| |
| /* In TCP mode, close the connection after this packet (if a response |
| is sent). */ |
| void resolv_response_close (struct resolv_response_builder *); |
| |
| /* The size of the response packet built so far. */ |
| size_t resolv_response_length (const struct resolv_response_builder *); |
| |
| __END_DECLS |
| |
| #endif /* SUPPORT_RESOLV_TEST_H */ |
