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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/dns/dns_config_service_posix.h"
#include <string>
#include "base/basictypes.h"
#include "base/bind.h"
#include "base/file_path.h"
#include "base/file_util.h"
#include "base/memory/scoped_ptr.h"
#include "net/base/ip_endpoint.h"
#include "net/base/net_util.h"
#include "net/dns/serial_worker.h"
namespace net {
namespace {
#ifndef _PATH_RESCONF // Normally defined in <resolv.h>
#define _PATH_RESCONF "/etc/resolv.conf"
#endif
const FilePath::CharType* kFilePathHosts = FILE_PATH_LITERAL("/etc/hosts");
// A SerialWorker that uses libresolv to initialize res_state and converts
// it to DnsConfig.
class ConfigReader : public SerialWorker {
public:
typedef base::Callback<void(const DnsConfig& config)> CallbackType;
explicit ConfigReader(const CallbackType& callback)
: callback_(callback),
success_(false) {}
void DoWork() OVERRIDE {
success_ = false;
#if defined(OS_ANDROID)
NOTIMPLEMENTED();
#elif defined(OS_OPENBSD)
// Note: res_ninit in glibc always returns 0 and sets RES_INIT.
// res_init behaves the same way.
memset(&_res, 0, sizeof(_res));
if ((res_init() == 0) && (_res.options & RES_INIT)) {
success_ = internal::ConvertResStateToDnsConfig(_res, &dns_config_);
}
#else // all other OS_POSIX
struct __res_state res;
memset(&res, 0, sizeof(res));
if ((res_ninit(&res) == 0) && (res.options & RES_INIT)) {
success_ = internal::ConvertResStateToDnsConfig(res, &dns_config_);
}
// Prefer res_ndestroy where available.
#if defined(OS_MACOSX) || defined(OS_FREEBSD)
res_ndestroy(&res);
#else
res_nclose(&res);
#endif
#endif
}
void OnWorkFinished() OVERRIDE {
DCHECK(!IsCancelled());
if (success_)
callback_.Run(dns_config_);
}
private:
virtual ~ConfigReader() {}
CallbackType callback_;
// Written in DoWork, read in OnWorkFinished, no locking necessary.
DnsConfig dns_config_;
bool success_;
};
} // namespace
namespace internal {
DnsConfigServicePosix::DnsConfigServicePosix() {
config_reader_ = new ConfigReader(
base::Bind(&DnsConfigServicePosix::OnConfigRead,
base::Unretained(this)));
hosts_reader_ = new DnsHostsReader(
FilePath(kFilePathHosts),
base::Bind(&DnsConfigServicePosix::OnHostsRead,
base::Unretained(this)));
}
DnsConfigServicePosix::~DnsConfigServicePosix() {
config_reader_->Cancel();
hosts_reader_->Cancel();
}
void DnsConfigServicePosix::OnDNSChanged(unsigned detail) {
if (detail & NetworkChangeNotifier::CHANGE_DNS_WATCH_FAILED) {
InvalidateConfig();
InvalidateHosts();
// We don't trust a config that we cannot watch in the future.
config_reader_->Cancel();
hosts_reader_->Cancel();
return;
}
if (detail & NetworkChangeNotifier::CHANGE_DNS_WATCH_STARTED)
detail = ~0; // Assume everything changed.
if (detail & NetworkChangeNotifier::CHANGE_DNS_SETTINGS) {
InvalidateConfig();
config_reader_->WorkNow();
}
if (detail & NetworkChangeNotifier::CHANGE_DNS_HOSTS) {
InvalidateHosts();
hosts_reader_->WorkNow();
}
}
#if !defined(OS_ANDROID)
bool ConvertResStateToDnsConfig(const struct __res_state& res,
DnsConfig* dns_config) {
CHECK(dns_config != NULL);
DCHECK(res.options & RES_INIT);
dns_config->nameservers.clear();
#if defined(OS_MACOSX) || defined(OS_FREEBSD)
union res_sockaddr_union addresses[MAXNS];
int nscount = res_getservers(const_cast<res_state>(&res), addresses, MAXNS);
DCHECK_GE(nscount, 0);
DCHECK_LE(nscount, MAXNS);
for (int i = 0; i < nscount; ++i) {
IPEndPoint ipe;
if (!ipe.FromSockAddr(
reinterpret_cast<const struct sockaddr*>(&addresses[i]),
sizeof addresses[i])) {
return false;
}
dns_config->nameservers.push_back(ipe);
}
#elif defined(OS_LINUX)
COMPILE_ASSERT(arraysize(res.nsaddr_list) >= MAXNS &&
arraysize(res._u._ext.nsaddrs) >= MAXNS,
incompatible_libresolv_res_state);
DCHECK_LE(res.nscount, MAXNS);
// Initially, glibc stores IPv6 in |_ext.nsaddrs| and IPv4 in |nsaddr_list|.
// In res_send.c:res_nsend, it merges |nsaddr_list| into |nsaddrs|,
// but we have to combine the two arrays ourselves.
for (int i = 0; i < res.nscount; ++i) {
IPEndPoint ipe;
const struct sockaddr* addr = NULL;
size_t addr_len = 0;
if (res.nsaddr_list[i].sin_family) { // The indicator used by res_nsend.
addr = reinterpret_cast<const struct sockaddr*>(&res.nsaddr_list[i]);
addr_len = sizeof res.nsaddr_list[i];
} else if (res._u._ext.nsaddrs[i] != NULL) {
addr = reinterpret_cast<const struct sockaddr*>(res._u._ext.nsaddrs[i]);
addr_len = sizeof *res._u._ext.nsaddrs[i];
} else {
return false;
}
if (!ipe.FromSockAddr(addr, addr_len))
return false;
dns_config->nameservers.push_back(ipe);
}
#else // !(defined(OS_LINUX) || defined(OS_MACOSX) || defined(OS_FREEBSD))
DCHECK_LE(res.nscount, MAXNS);
for (int i = 0; i < res.nscount; ++i) {
IPEndPoint ipe;
if (!ipe.FromSockAddr(
reinterpret_cast<const struct sockaddr*>(&res.nsaddr_list[i]),
sizeof res.nsaddr_list[i])) {
return false;
}
dns_config->nameservers.push_back(ipe);
}
#endif
dns_config->search.clear();
for (int i = 0; (i < MAXDNSRCH) && res.dnsrch[i]; ++i) {
dns_config->search.push_back(std::string(res.dnsrch[i]));
}
dns_config->ndots = res.ndots;
dns_config->timeout = base::TimeDelta::FromSeconds(res.retrans);
dns_config->attempts = res.retry;
#if defined(RES_ROTATE)
dns_config->rotate = res.options & RES_ROTATE;
#endif
dns_config->edns0 = res.options & RES_USE_EDNS0;
return true;
}
#endif // !defined(OS_ANDROID)
} // namespace internal
// static
scoped_ptr<DnsConfigService> DnsConfigService::CreateSystemService() {
return scoped_ptr<DnsConfigService>(new internal::DnsConfigServicePosix());
}
} // namespace net
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