1 //
2 // Copyright (C) 2015 The Android Open Source Project
3 //
4 // Licensed under the Apache License, Version 2.0 (the "License");
5 // you may not use this file except in compliance with the License.
6 // You may obtain a copy of the License at
7 //
8 // http://www.apache.org/licenses/LICENSE-2.0
9 //
10 // Unless required by applicable law or agreed to in writing, software
11 // distributed under the License is distributed on an "AS IS" BASIS,
12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 // See the License for the specific language governing permissions and
14 // limitations under the License.
15 //
16
17 #include "shill/dns_server_proxy.h"
18
19 #include <map>
20
21 #include <base/bind.h>
22 #include <base/strings/stringprintf.h>
23
24 #include "shill/logging.h"
25 #include "shill/process_manager.h"
26
27 using std::string;
28 using std::vector;
29
30 namespace shill {
31
32 namespace {
33 const char kDnsmasqPath[] = "/system/bin/dnsmasq";
34 const char kDnsmasqPidFilePath[] = "/data/misc/shill/dnsmasq.pid";
35 const char kDnsmasqUser[] = "system";
36 const char kDnsmasqGroup[] = "system";
37 const int kInvalidPID = -1;
38 }
39
DNSServerProxy(const vector<string> & dns_servers)40 DNSServerProxy::DNSServerProxy(const vector<string>& dns_servers)
41 : process_manager_(ProcessManager::GetInstance()),
42 pid_(kInvalidPID),
43 dns_servers_(dns_servers) {}
44
~DNSServerProxy()45 DNSServerProxy::~DNSServerProxy() {
46 if (pid_ != kInvalidPID) {
47 Stop();
48 }
49 }
50
Start()51 bool DNSServerProxy::Start() {
52 if (pid_ != kInvalidPID) {
53 LOG(ERROR) << __func__ << ": already started";
54 return false;
55 }
56 // Setup command line arguments for dnsmasq.
57 vector<string> args;
58 args.push_back("--no-hosts");
59 args.push_back("--listen-address=127.0.0.1");
60 args.push_back("--no-resolv");
61 args.push_back("--keep-in-foreground");
62 args.push_back(base::StringPrintf("--user=%s", kDnsmasqUser));
63 args.push_back(base::StringPrintf("--group=%s", kDnsmasqGroup));
64 for (const auto& server : dns_servers_) {
65 args.push_back(base::StringPrintf("--server=%s", server.c_str()));
66 }
67 args.push_back(base::StringPrintf("--pid-file=%s", kDnsmasqPidFilePath));
68 // Start dnsmasq.
69 // TODO(zqiu): start dnsmasq with Minijail when the latter is working on
70 // Android (b/24572800).
71 pid_t pid =
72 process_manager_->StartProcess(
73 FROM_HERE,
74 base::FilePath(kDnsmasqPath),
75 args,
76 std::map<string, string>(), // No environment variables needed.
77 true, // Terminate with parent.
78 base::Bind(&DNSServerProxy::OnProcessExited,
79 weak_factory_.GetWeakPtr()));
80 if (pid < 0) {
81 return false;
82 }
83
84 pid_ = pid;
85 LOG(INFO) << "Spawned " << kDnsmasqPath << " with pid: " << pid_;
86 return true;
87 }
88
Stop()89 void DNSServerProxy::Stop() {
90 if (pid_ == kInvalidPID) {
91 LOG(ERROR) << __func__ << ": already stopped";
92 return;
93 }
94 process_manager_->StopProcess(pid_);
95 }
96
OnProcessExited(int exit_status)97 void DNSServerProxy::OnProcessExited(int exit_status) {
98 CHECK(pid_);
99 if (exit_status != EXIT_SUCCESS) {
100 LOG(WARNING) << "pid " << pid_ << " exit status " << exit_status;
101 }
102 pid_ = kInvalidPID;
103 }
104
105 } // namespace shill
106