1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
|
/* DNS test framework and libresolv redirection.
Copyright (C) 2016-2017 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;
};
/* 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 */
|
