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
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
#![allow(dead_code)]
#![allow(unused_imports)]

cfg_if::cfg_if! {
    if #[cfg(windows)] {
        use windows::{
            core::*,
            Win32::NetworkManagement::Dns::*,
        };
        use winreg::RegKey;
        use winreg::enums::*;
        use std::ptr::{null_mut};
        use core::ffi::{c_void};

        pub fn dns_query_srv_records(name: &str) -> Vec<String> {
            let mut records = Vec::new();
            unsafe {
                let mut p_query_results: *mut DNS_RECORDA = null_mut();
                let dns_status = DnsQuery_W(&HSTRING::from(name), DNS_TYPE_SRV,
                    DNS_QUERY_STANDARD, None, &mut p_query_results, None);

                match dns_status {
                    Ok(()) => {
                        let p_name_target = (*p_query_results).Data.Srv.pNameTarget;
                        if let Ok(name_target) = PWSTR::from_raw(p_name_target.as_ptr() as *mut u16).to_string() {
                            records.push(name_target);
                        }
                    }
                    Err(error) => error!(%error, "DnsQuery_W failed"),
                }

                DnsFree(Some(p_query_results as *const c_void), DnsFreeRecordList);
            }
            records
        }

        pub struct DnsClientNrptRule {
            rule_name: String,
            namespace: String,
            name_servers: Vec<String>
        }

        pub fn get_dns_client_nrpt_rules() -> Vec<DnsClientNrptRule> {
            let mut rules: Vec<DnsClientNrptRule> = Vec::new();
            let hklm = RegKey::predef(HKEY_LOCAL_MACHINE);
            let dns_policy_config_key_path = "System\\CurrentControlSet\\Services\\Dnscache\\Parameters\\DnsPolicyConfig";
            if let Ok(dns_policy_config_key) = hklm.open_subkey(dns_policy_config_key_path) {
                for rule_name in dns_policy_config_key.enum_keys().map(|x| x.unwrap()) {
                    let dns_policy_rule_key_path = format!("{}\\{}", dns_policy_config_key_path, &rule_name);
                    if let Ok(dns_policy_rule_key) = hklm.open_subkey(dns_policy_rule_key_path) {
                        let namespace: Option<String> = dns_policy_rule_key.get_value("Name").ok(); // REG_MULTI_SZ
                        let name_server_list: Option<String> = dns_policy_rule_key.get_value("GenericDNSServers").ok(); // REG_SZ
                        if let (Some(namespace), Some(name_server_list)) = (namespace, name_server_list) {
                            let name_servers: Vec<String> = name_server_list.split(';').map(|x| x.to_string()).collect();
                            rules.push(DnsClientNrptRule {
                                rule_name,
                                namespace,
                                name_servers,
                            });
                        }
                    }
                }
            }
            rules
        }

        pub fn get_default_name_servers() -> Vec<String> {
            let hklm = RegKey::predef(HKEY_LOCAL_MACHINE);
            let tcpip_linkage_key_path = "SYSTEM\\CurrentControlSet\\Services\\Tcpip\\Linkage";
            let tcpip_interfaces_key_path = "SYSTEM\\CurrentControlSet\\Services\\Tcpip\\Parameters\\Interfaces";
            let dns_registered_adapters_key_path = "SYSTEM\\CurrentControlSet\\Services\\Tcpip\\Parameters\\DNSRegisteredAdapters";

            if let Ok(tcpip_linkage_key) = hklm.open_subkey(tcpip_linkage_key_path) {
                let bind_devices: Vec<String> = tcpip_linkage_key.get_value("Bind").unwrap();
                let device_ids = bind_devices.iter().map(|x| x.strip_prefix("\\Device\\").unwrap());

                for device_id in device_ids {
                    let interface_key_path = format!("{}\\{}", tcpip_interfaces_key_path, &device_id);
                    let dns_adapter_key_path = format!("{}\\{}", dns_registered_adapters_key_path, &device_id);

                    if let (Ok(interface_key), Ok(dns_adapter_key)) = (hklm.open_subkey(interface_key_path), hklm.open_subkey(dns_adapter_key_path)) {
                        let name_server: Option<String> = interface_key.get_value("NameServer").ok().filter(|x: &String| !x.is_empty());
                        let dhcp_name_server: Option<String> = interface_key.get_value("DhcpNameServer").ok().filter(|x: &String| !x.is_empty());
                        let stale_adapter: u32 = dns_adapter_key.get_value("StaleAdapter").unwrap_or(1);

                        if stale_adapter != 1 {
                            if let Some(name_server_list) = name_server.or(dhcp_name_server) {
                                let name_servers: Vec<String> = name_server_list.split(' ')
                                    .map(|c| c.trim().to_string()).filter(|x: &String| !x.is_empty()).collect();
                                return name_servers;
                            }
                        }
                    }
                }
            }
            Vec::new()
        }

        pub fn get_name_servers_for_domain(domain: &str) -> Vec<String> {
            let domain_namespace = if domain.starts_with('.') {
                domain.to_string()
            } else {
                format!(".{}", &domain)
            };

            for nrpt_rule in get_dns_client_nrpt_rules() {
                if nrpt_rule.namespace.ends_with(&domain_namespace) {
                    return nrpt_rule.name_servers;
                }
            }

            get_default_name_servers()
        }

        pub fn detect_kdc_hosts_from_dns_windows(domain: &str) -> Vec<String> {
            let krb_tcp_name = &format!("_kerberos._tcp.{}", domain);
            let krb_tcp_srv = dns_query_srv_records(krb_tcp_name);

            if !krb_tcp_srv.is_empty() {
                return krb_tcp_srv.iter().map(|x| format!("tcp://{}:88", x)).collect()
            }

            let krb_udp_name = &format!("_kerberos._udp.{}", domain);
            let krb_udp_srv = dns_query_srv_records(krb_udp_name);

            if !krb_udp_srv.is_empty() {
                return krb_udp_srv.iter().map(|x| format!("udp://{}:88", x)).collect()
            }

            Vec::new()
        }
    }
}

cfg_if::cfg_if! {
    if #[cfg(any(target_os="macos", target_os="ios"))] {
        use std::time::Duration;
        use tokio::time::timeout;
        use futures::stream::{StreamExt};
        use async_dnssd::{query_record, QueryRecordResult, QueriedRecordFlags, Type};

        #[derive(Clone)]
        pub struct DnsSrvRecord {
            priority: u16,
            weight: u16,
            port: u16,
            target: String
        }

        impl From<&QueryRecordResult> for DnsSrvRecord {
            fn from(record: &QueryRecordResult) -> Self {
                let rdata = record.rdata.as_slice();
                let priority = u16::from_be_bytes(rdata[0..2].try_into().unwrap());
                let weight = u16::from_be_bytes(rdata[2..4].try_into().unwrap());
                let port = u16::from_be_bytes(rdata[4..6].try_into().unwrap());
                let target_data = &rdata[6..rdata.len()];
                DnsSrvRecord {
                    priority,
                    weight,
                    port,
                    target: dns_decode_target_data_to_string(target_data)
                }
            }
        }

        pub fn dns_decode_target_data_to_string(v: &[u8]) -> String {
            let mut names = Vec::new();

            let mut i = 0;
            while i < v.len() {
                let size = v[i] as usize;
                if size == 0 || i + 1 + size > v.len() {
                    break;
                }
                names.push(String::from_utf8_lossy(&v[i+1..i+1+size]));
                i = i + 1 + size;
            }

            names.join(".")
        }

        pub fn dns_query_srv_records(name: &str) -> Vec<DnsSrvRecord> {
            const QUERY_TIMEOUT: u64 = 1000;

            async fn query_with_timeout(name: &str, query_timeout: u64) -> Vec<DnsSrvRecord> {
                let mut dns_records: Vec<DnsSrvRecord> = Vec::new();
                let mut query = query_record(name, Type::SRV);

                loop {
                    match timeout(Duration::from_millis(query_timeout), query.next()).await {
                        Ok(Some(Ok(dns_record))) => {
                            let srv_record: DnsSrvRecord = (&dns_record).into();
                            dns_records.push(srv_record.to_owned());
                            if !dns_record.flags.contains(QueriedRecordFlags::MORE_COMING) {
                                break;
                            }
                        }
                        Ok(None) => {
                            break
                        }
                        Ok(Some(Err(error))) => {
                            error!(%error, "IO error when reading DNS query");
                            break;
                        }
                        Err(error) => {
                            error!(%error, "Timeout when reading DNS query");
                            break;
                        }
                    }
                }

                dns_records
            }

            execute_future(query_with_timeout(name, QUERY_TIMEOUT))
        }

        pub fn detect_kdc_hosts_from_dns_apple(domain: &str) -> Vec<String> {
            let krb_tcp_name = &format!("_kerberos._tcp.{}", domain);
            let krb_tcp_srv = dns_query_srv_records(krb_tcp_name);

            if !krb_tcp_srv.is_empty() {
                return krb_tcp_srv.iter().map(|x| format!("tcp://{}:{}", &x.target, x.port)).collect()
            }

            let krb_udp_name = &format!("_kerberos._udp.{}", domain);
            let krb_udp_srv = dns_query_srv_records(krb_udp_name);

            if !krb_udp_srv.is_empty() {
                return krb_udp_srv.iter().map(|x| format!("udp://{}:{}", &x.target, x.port)).collect()
            }

            Vec::new()
        }
    }
}

cfg_if::cfg_if! {
    if #[cfg(feature="dns_resolver")] {
        use trust_dns_resolver::TokioAsyncResolver;
        use trust_dns_resolver::system_conf::read_system_conf;
        use trust_dns_resolver::config::{ResolverConfig,NameServerConfig,Protocol,ResolverOpts};
        use std::env;
        use std::net::{IpAddr,SocketAddr};
        use std::str::FromStr;
        use url::Url;

        fn get_trust_dns_name_server_from_url_str(url: &str) -> Option<NameServerConfig> {
            let url = if !url.contains("://") && !url.is_empty() {
                format!("udp://{}", url)
            } else {
                url.to_string()
            };

            if let Ok(url) = Url::parse(&url) {
                if let Some(url_host) = url.host_str() {
                    let url_port = url.port().unwrap_or(53);
                    let protocol = match url.scheme().to_lowercase().as_str() {
                        "tcp" => Protocol::Tcp,
                        "udp" => Protocol::Udp,
                        _ => Protocol::Udp,
                    };
                    if let Ok(ip_addr) = IpAddr::from_str(url_host) {
                        let socket_addr = SocketAddr::new(ip_addr, url_port);
                        return Some(NameServerConfig {
                            socket_addr,
                            protocol,
                            tls_dns_name: None,
                            trust_negative_responses: false,
                            bind_addr: None
                        });
                    }
                }
            }

            None
        }

        fn get_trust_dns_resolver_from_name_servers(name_servers: Vec<String>) -> TokioAsyncResolver {
            let mut resolver_config = ResolverConfig::new();

            for name_server_url in name_servers {
                if let Some(name_server) = get_trust_dns_name_server_from_url_str(&name_server_url) {
                    resolver_config.add_name_server(name_server);
                }
            }

            let mut resolver_options = ResolverOpts::default();
            resolver_options.validate = false;

            TokioAsyncResolver::tokio(resolver_config, resolver_options)
        }

        #[cfg(target_os="windows")]
        fn get_trust_dns_resolver(domain: &str) -> Option<TokioAsyncResolver> {
            let name_servers = get_name_servers_for_domain(domain);
            Some(get_trust_dns_resolver_from_name_servers(name_servers))
        }

        #[cfg(not(target_os="windows"))]
        fn get_trust_dns_resolver(_domain: &str) -> Option<TokioAsyncResolver> {
            if let Ok(name_server_list) = env::var("SSPI_DNS_URL") {
                let name_servers: Vec<String> = name_server_list
                    .split(',').map(|c|c.trim()).filter(|x| !x.is_empty()).map(String::from).collect();
                Some(get_trust_dns_resolver_from_name_servers(name_servers))
            } else if let Ok((resolver_config, resolver_options)) = read_system_conf() {
                Some(TokioAsyncResolver::tokio(resolver_config, resolver_options))
            } else {
                None
            }
        }

        pub fn detect_kdc_hosts_from_dns_trust(domain: &str) -> Vec<String> {
            let mut kdc_hosts = Vec::new();

            if let Some(resolver) = get_trust_dns_resolver(domain) {
                if let Ok(records) = execute_future(resolver.srv_lookup(format!("_kerberos._tcp.{}", domain))) {
                    for record in records {
                        let port = record.port();
                        let target_name = record.target().to_string();
                        let target_name = target_name.trim_end_matches('.').to_string();
                        let kdc_host = format!("tcp://{}:{}", &target_name, port);
                        kdc_hosts.push(kdc_host);
                    }
                }

                if let Ok(records) = execute_future(resolver.srv_lookup(format!("_kerberos._udp.{}", domain))) {
                    for record in records {
                        let port = record.port();
                        let target_name = record.target().to_string();
                        let target_name = target_name.trim_end_matches('.').to_string();
                        let kdc_host = format!("udp://{}:{}", &target_name, port);
                        kdc_hosts.push(kdc_host);
                    }
                }
            }

            kdc_hosts
        }
    }
}

#[cfg(any(feature = "dns_resolver", target_os = "macos", target_os = "ios"))]
fn execute_future<Fut>(fut: Fut) -> Fut::Output
where
    Fut: std::future::IntoFuture + Send,
    Fut::Output: Send,
{
    use std::thread;

    use tokio::runtime::{Builder, Handle, Runtime, RuntimeFlavor};
    use tokio::task;

    fn new_runtime() -> Runtime {
        Builder::new_current_thread().enable_all().build().unwrap()
    }

    match Handle::try_current() {
        Ok(handle) => {
            match handle.runtime_flavor() {
                RuntimeFlavor::CurrentThread => thread::scope(|s| {
                    s.spawn(move || new_runtime().block_on(fut.into_future()))
                        .join()
                        .unwrap()
                }),
                // block_in_place can't be used in current_thread runtime
                _ => task::block_in_place(move || handle.block_on(fut.into_future())),
            }
        }
        Err(_) => new_runtime().block_on(fut.into_future()),
    }
}

#[allow(unused_variables)]
#[instrument(level = "debug", ret)]
pub fn detect_kdc_hosts_from_dns(domain: &str) -> Vec<String> {
    cfg_if::cfg_if! {
        if #[cfg(windows)] {
            detect_kdc_hosts_from_dns_windows(domain)
        } else if #[cfg(any(target_os="macos", target_os="ios"))] {
            detect_kdc_hosts_from_dns_apple(domain)
        } else if #[cfg(feature="dns_resolver")] {
            detect_kdc_hosts_from_dns_trust(domain)
        } else {
            Vec::new()
        }
    }
}