1 // Copyright 2014 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "net/dns/dns_config_watcher_mac.h"
6
7 #include <dlfcn.h>
8
9 #include "base/lazy_instance.h"
10 #include "third_party/apple_apsl/dnsinfo.h"
11
12 namespace {
13
14 // dnsinfo symbols are available via libSystem.dylib, but can also be present in
15 // SystemConfiguration.framework. To avoid confusion, load them explicitly from
16 // libSystem.dylib.
17 class DnsInfoApi {
18 public:
19 typedef const char* (*dns_configuration_notify_key_t)();
20 typedef dns_config_t* (*dns_configuration_copy_t)();
21 typedef void (*dns_configuration_free_t)(dns_config_t*);
22
DnsInfoApi()23 DnsInfoApi()
24 : dns_configuration_notify_key(NULL),
25 dns_configuration_copy(NULL),
26 dns_configuration_free(NULL) {
27 handle_ = dlopen("/usr/lib/libSystem.dylib",
28 RTLD_LAZY | RTLD_NOLOAD);
29 if (!handle_)
30 return;
31 dns_configuration_notify_key =
32 reinterpret_cast<dns_configuration_notify_key_t>(
33 dlsym(handle_, "dns_configuration_notify_key"));
34 dns_configuration_copy =
35 reinterpret_cast<dns_configuration_copy_t>(
36 dlsym(handle_, "dns_configuration_copy"));
37 dns_configuration_free =
38 reinterpret_cast<dns_configuration_free_t>(
39 dlsym(handle_, "dns_configuration_free"));
40 }
41
~DnsInfoApi()42 ~DnsInfoApi() {
43 if (handle_)
44 dlclose(handle_);
45 }
46
47 dns_configuration_notify_key_t dns_configuration_notify_key;
48 dns_configuration_copy_t dns_configuration_copy;
49 dns_configuration_free_t dns_configuration_free;
50
51 private:
52 void* handle_;
53 };
54
GetDnsInfoApi()55 const DnsInfoApi& GetDnsInfoApi() {
56 static base::LazyInstance<DnsInfoApi>::Leaky api = LAZY_INSTANCE_INITIALIZER;
57 return api.Get();
58 }
59
60 struct DnsConfigTDeleter {
operator ()__anon36202df70111::DnsConfigTDeleter61 inline void operator()(dns_config_t* ptr) const {
62 if (GetDnsInfoApi().dns_configuration_free)
63 GetDnsInfoApi().dns_configuration_free(ptr);
64 }
65 };
66
67 } // namespace
68
69 namespace net {
70 namespace internal {
71
Watch(const base::Callback<void (bool succeeded)> & callback)72 bool DnsConfigWatcher::Watch(
73 const base::Callback<void(bool succeeded)>& callback) {
74 if (!GetDnsInfoApi().dns_configuration_notify_key)
75 return false;
76 return watcher_.Watch(GetDnsInfoApi().dns_configuration_notify_key(),
77 callback);
78 }
79
80 // static
CheckDnsConfig()81 ConfigParsePosixResult DnsConfigWatcher::CheckDnsConfig() {
82 if (!GetDnsInfoApi().dns_configuration_copy)
83 return CONFIG_PARSE_POSIX_NO_DNSINFO;
84 scoped_ptr<dns_config_t, DnsConfigTDeleter> dns_config(
85 GetDnsInfoApi().dns_configuration_copy());
86 if (!dns_config)
87 return CONFIG_PARSE_POSIX_NO_DNSINFO;
88
89 // TODO(szym): Parse dns_config_t for resolvers rather than res_state.
90 // DnsClient can't handle domain-specific unscoped resolvers.
91 unsigned num_resolvers = 0;
92 for (int i = 0; i < dns_config->n_resolver; ++i) {
93 dns_resolver_t* resolver = dns_config->resolver[i];
94 if (!resolver->n_nameserver)
95 continue;
96 if (resolver->options && !strcmp(resolver->options, "mdns"))
97 continue;
98 ++num_resolvers;
99 }
100 if (num_resolvers > 1)
101 return CONFIG_PARSE_POSIX_UNHANDLED_OPTIONS;
102 return CONFIG_PARSE_POSIX_OK;
103 }
104
105 } // namespace internal
106 } // namespace net
107