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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/address_sorter_posix.h"
#include <netinet/in.h>
#if defined(OS_MACOSX) || defined(OS_BSD)
#include <sys/socket.h> // Must be included before ifaddrs.h.
#include <ifaddrs.h>
#include <net/if.h>
#include <netinet/in_var.h>
#include <string.h>
#include <sys/ioctl.h>
#endif
#include <algorithm>
#include "base/logging.h"
#include "base/memory/scoped_vector.h"
#include "net/base/net_errors.h"
#include "net/socket/client_socket_factory.h"
#include "net/udp/datagram_client_socket.h"
#if defined(OS_LINUX)
#include "net/base/address_tracker_linux.h"
#endif
namespace net {
namespace {
// Address sorting is performed according to RFC3484 with revisions.
// http://tools.ietf.org/html/draft-ietf-6man-rfc3484bis-06
// Precedence and label are separate to support override through /etc/gai.conf.
// Returns true if |p1| should precede |p2| in the table.
// Sorts table by decreasing prefix size to allow longest prefix matching.
bool ComparePolicy(const AddressSorterPosix::PolicyEntry& p1,
const AddressSorterPosix::PolicyEntry& p2) {
return p1.prefix_length > p2.prefix_length;
}
// Creates sorted PolicyTable from |table| with |size| entries.
AddressSorterPosix::PolicyTable LoadPolicy(
AddressSorterPosix::PolicyEntry* table,
size_t size) {
AddressSorterPosix::PolicyTable result(table, table + size);
std::sort(result.begin(), result.end(), ComparePolicy);
return result;
}
// Search |table| for matching prefix of |address|. |table| must be sorted by
// descending prefix (prefix of another prefix must be later in table).
unsigned GetPolicyValue(const AddressSorterPosix::PolicyTable& table,
const IPAddressNumber& address) {
if (address.size() == kIPv4AddressSize)
return GetPolicyValue(table, ConvertIPv4NumberToIPv6Number(address));
for (unsigned i = 0; i < table.size(); ++i) {
const AddressSorterPosix::PolicyEntry& entry = table[i];
IPAddressNumber prefix(entry.prefix, entry.prefix + kIPv6AddressSize);
if (IPNumberMatchesPrefix(address, prefix, entry.prefix_length))
return entry.value;
}
NOTREACHED();
// The last entry is the least restrictive, so assume it's default.
return table.back().value;
}
bool IsIPv6Multicast(const IPAddressNumber& address) {
DCHECK_EQ(kIPv6AddressSize, address.size());
return address[0] == 0xFF;
}
AddressSorterPosix::AddressScope GetIPv6MulticastScope(
const IPAddressNumber& address) {
DCHECK_EQ(kIPv6AddressSize, address.size());
return static_cast<AddressSorterPosix::AddressScope>(address[1] & 0x0F);
}
bool IsIPv6Loopback(const IPAddressNumber& address) {
DCHECK_EQ(kIPv6AddressSize, address.size());
// IN6_IS_ADDR_LOOPBACK
unsigned char kLoopback[kIPv6AddressSize] = {
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 1,
};
return address == IPAddressNumber(kLoopback, kLoopback + kIPv6AddressSize);
}
bool IsIPv6LinkLocal(const IPAddressNumber& address) {
DCHECK_EQ(kIPv6AddressSize, address.size());
// IN6_IS_ADDR_LINKLOCAL
return (address[0] == 0xFE) && ((address[1] & 0xC0) == 0x80);
}
bool IsIPv6SiteLocal(const IPAddressNumber& address) {
DCHECK_EQ(kIPv6AddressSize, address.size());
// IN6_IS_ADDR_SITELOCAL
return (address[0] == 0xFE) && ((address[1] & 0xC0) == 0xC0);
}
AddressSorterPosix::AddressScope GetScope(
const AddressSorterPosix::PolicyTable& ipv4_scope_table,
const IPAddressNumber& address) {
if (address.size() == kIPv6AddressSize) {
if (IsIPv6Multicast(address)) {
return GetIPv6MulticastScope(address);
} else if (IsIPv6Loopback(address) || IsIPv6LinkLocal(address)) {
return AddressSorterPosix::SCOPE_LINKLOCAL;
} else if (IsIPv6SiteLocal(address)) {
return AddressSorterPosix::SCOPE_SITELOCAL;
} else {
return AddressSorterPosix::SCOPE_GLOBAL;
}
} else if (address.size() == kIPv4AddressSize) {
return static_cast<AddressSorterPosix::AddressScope>(
GetPolicyValue(ipv4_scope_table, address));
} else {
NOTREACHED();
return AddressSorterPosix::SCOPE_NODELOCAL;
}
}
// Default policy table. RFC 3484, Section 2.1.
AddressSorterPosix::PolicyEntry kDefaultPrecedenceTable[] = {
// ::1/128 -- loopback
{ { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 }, 128, 50 },
// ::/0 -- any
{ { }, 0, 40 },
// ::ffff:0:0/96 -- IPv4 mapped
{ { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF }, 96, 35 },
// 2002::/16 -- 6to4
{ { 0x20, 0x02, }, 16, 30 },
// 2001::/32 -- Teredo
{ { 0x20, 0x01, 0, 0 }, 32, 5 },
// fc00::/7 -- unique local address
{ { 0xFC }, 7, 3 },
// ::/96 -- IPv4 compatible
{ { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, 96, 1 },
// fec0::/10 -- site-local expanded scope
{ { 0xFE, 0xC0 }, 10, 1 },
// 3ffe::/16 -- 6bone
{ { 0x3F, 0xFE }, 16, 1 },
};
AddressSorterPosix::PolicyEntry kDefaultLabelTable[] = {
// ::1/128 -- loopback
{ { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 }, 128, 0 },
// ::/0 -- any
{ { }, 0, 1 },
// ::ffff:0:0/96 -- IPv4 mapped
{ { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF }, 96, 4 },
// 2002::/16 -- 6to4
{ { 0x20, 0x02, }, 16, 2 },
// 2001::/32 -- Teredo
{ { 0x20, 0x01, 0, 0 }, 32, 5 },
// fc00::/7 -- unique local address
{ { 0xFC }, 7, 13 },
// ::/96 -- IPv4 compatible
{ { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, 96, 3 },
// fec0::/10 -- site-local expanded scope
{ { 0xFE, 0xC0 }, 10, 11 },
// 3ffe::/16 -- 6bone
{ { 0x3F, 0xFE }, 16, 12 },
};
// Default mapping of IPv4 addresses to scope.
AddressSorterPosix::PolicyEntry kDefaultIPv4ScopeTable[] = {
{ { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF, 0x7F }, 104,
AddressSorterPosix::SCOPE_LINKLOCAL },
{ { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF, 0xA9, 0xFE }, 112,
AddressSorterPosix::SCOPE_LINKLOCAL },
{ { }, 0, AddressSorterPosix::SCOPE_GLOBAL },
};
struct DestinationInfo {
IPAddressNumber address;
AddressSorterPosix::AddressScope scope;
unsigned precedence;
unsigned label;
const AddressSorterPosix::SourceAddressInfo* src;
unsigned common_prefix_length;
};
// Returns true iff |dst_a| should precede |dst_b| in the address list.
// RFC 3484, section 6.
bool CompareDestinations(const DestinationInfo* dst_a,
const DestinationInfo* dst_b) {
// Rule 1: Avoid unusable destinations.
// Unusable destinations are already filtered out.
DCHECK(dst_a->src);
DCHECK(dst_b->src);
// Rule 2: Prefer matching scope.
bool scope_match1 = (dst_a->src->scope == dst_a->scope);
bool scope_match2 = (dst_b->src->scope == dst_b->scope);
if (scope_match1 != scope_match2)
return scope_match1;
// Rule 3: Avoid deprecated addresses.
if (dst_a->src->deprecated != dst_b->src->deprecated)
return !dst_a->src->deprecated;
// Rule 4: Prefer home addresses.
if (dst_a->src->home != dst_b->src->home)
return dst_a->src->home;
// Rule 5: Prefer matching label.
bool label_match1 = (dst_a->src->label == dst_a->label);
bool label_match2 = (dst_b->src->label == dst_b->label);
if (label_match1 != label_match2)
return label_match1;
// Rule 6: Prefer higher precedence.
if (dst_a->precedence != dst_b->precedence)
return dst_a->precedence > dst_b->precedence;
// Rule 7: Prefer native transport.
if (dst_a->src->native != dst_b->src->native)
return dst_a->src->native;
// Rule 8: Prefer smaller scope.
if (dst_a->scope != dst_b->scope)
return dst_a->scope < dst_b->scope;
// Rule 9: Use longest matching prefix. Only for matching address families.
if (dst_a->address.size() == dst_b->address.size()) {
if (dst_a->common_prefix_length != dst_b->common_prefix_length)
return dst_a->common_prefix_length > dst_b->common_prefix_length;
}
// Rule 10: Leave the order unchanged.
// stable_sort takes care of that.
return false;
}
} // namespace
AddressSorterPosix::AddressSorterPosix(ClientSocketFactory* socket_factory)
: socket_factory_(socket_factory),
precedence_table_(LoadPolicy(kDefaultPrecedenceTable,
arraysize(kDefaultPrecedenceTable))),
label_table_(LoadPolicy(kDefaultLabelTable,
arraysize(kDefaultLabelTable))),
ipv4_scope_table_(LoadPolicy(kDefaultIPv4ScopeTable,
arraysize(kDefaultIPv4ScopeTable))) {
NetworkChangeNotifier::AddIPAddressObserver(this);
OnIPAddressChanged();
}
AddressSorterPosix::~AddressSorterPosix() {
NetworkChangeNotifier::RemoveIPAddressObserver(this);
}
void AddressSorterPosix::Sort(const AddressList& list,
const CallbackType& callback) const {
DCHECK(CalledOnValidThread());
ScopedVector<DestinationInfo> sort_list;
for (size_t i = 0; i < list.size(); ++i) {
scoped_ptr<DestinationInfo> info(new DestinationInfo());
info->address = list[i].address();
info->scope = GetScope(ipv4_scope_table_, info->address);
info->precedence = GetPolicyValue(precedence_table_, info->address);
info->label = GetPolicyValue(label_table_, info->address);
// Each socket can only be bound once.
scoped_ptr<DatagramClientSocket> socket(
socket_factory_->CreateDatagramClientSocket(
DatagramSocket::DEFAULT_BIND,
RandIntCallback(),
NULL /* NetLog */,
NetLog::Source()));
// Even though no packets are sent, cannot use port 0 in Connect.
IPEndPoint dest(info->address, 80 /* port */);
int rv = socket->Connect(dest);
if (rv != OK) {
VLOG(1) << "Could not connect to " << dest.ToStringWithoutPort()
<< " reason " << rv;
continue;
}
// Filter out unusable destinations.
IPEndPoint src;
rv = socket->GetLocalAddress(&src);
if (rv != OK) {
LOG(WARNING) << "Could not get local address for "
<< dest.ToStringWithoutPort() << " reason " << rv;
continue;
}
SourceAddressInfo& src_info = source_map_[src.address()];
if (src_info.scope == SCOPE_UNDEFINED) {
// If |source_info_| is out of date, |src| might be missing, but we still
// want to sort, even though the HostCache will be cleared soon.
FillPolicy(src.address(), &src_info);
}
info->src = &src_info;
if (info->address.size() == src.address().size()) {
info->common_prefix_length = std::min(
CommonPrefixLength(info->address, src.address()),
info->src->prefix_length);
}
sort_list.push_back(info.Pass());
}
std::stable_sort(sort_list.begin(), sort_list.end(), CompareDestinations);
AddressList result;
for (size_t i = 0; i < sort_list.size(); ++i)
result.push_back(IPEndPoint(sort_list[i]->address, 0 /* port */));
callback.Run(true, result);
}
void AddressSorterPosix::OnIPAddressChanged() {
DCHECK(CalledOnValidThread());
source_map_.clear();
#if defined(OS_LINUX)
const internal::AddressTrackerLinux* tracker =
NetworkChangeNotifier::GetAddressTracker();
if (!tracker)
return;
typedef internal::AddressTrackerLinux::AddressMap AddressMap;
AddressMap map = tracker->GetAddressMap();
for (AddressMap::const_iterator it = map.begin(); it != map.end(); ++it) {
const IPAddressNumber& address = it->first;
const struct ifaddrmsg& msg = it->second;
SourceAddressInfo& info = source_map_[address];
info.native = false; // TODO(szym): obtain this via netlink.
info.deprecated = msg.ifa_flags & IFA_F_DEPRECATED;
info.home = msg.ifa_flags & IFA_F_HOMEADDRESS;
info.prefix_length = msg.ifa_prefixlen;
FillPolicy(address, &info);
}
#elif defined(OS_MACOSX) || defined(OS_BSD)
// It's not clear we will receive notification when deprecated flag changes.
// Socket for ioctl.
int ioctl_socket = socket(AF_INET6, SOCK_DGRAM, 0);
if (ioctl_socket < 0)
return;
struct ifaddrs* addrs;
int rv = getifaddrs(&addrs);
if (rv < 0) {
LOG(WARNING) << "getifaddrs failed " << rv;
close(ioctl_socket);
return;
}
for (struct ifaddrs* ifa = addrs; ifa != NULL; ifa = ifa->ifa_next) {
IPEndPoint src;
if (!src.FromSockAddr(ifa->ifa_addr, ifa->ifa_addr->sa_len))
continue;
SourceAddressInfo& info = source_map_[src.address()];
// Note: no known way to fill in |native| and |home|.
info.native = info.home = info.deprecated = false;
if (ifa->ifa_addr->sa_family == AF_INET6) {
struct in6_ifreq ifr = {};
strncpy(ifr.ifr_name, ifa->ifa_name, sizeof(ifr.ifr_name) - 1);
DCHECK_LE(ifa->ifa_addr->sa_len, sizeof(ifr.ifr_ifru.ifru_addr));
memcpy(&ifr.ifr_ifru.ifru_addr, ifa->ifa_addr, ifa->ifa_addr->sa_len);
int rv = ioctl(ioctl_socket, SIOCGIFAFLAG_IN6, &ifr);
if (rv >= 0) {
info.deprecated = ifr.ifr_ifru.ifru_flags & IN6_IFF_DEPRECATED;
} else {
LOG(WARNING) << "SIOCGIFAFLAG_IN6 failed " << rv;
}
}
if (ifa->ifa_netmask) {
IPEndPoint netmask;
if (netmask.FromSockAddr(ifa->ifa_netmask, ifa->ifa_addr->sa_len)) {
info.prefix_length = MaskPrefixLength(netmask.address());
} else {
LOG(WARNING) << "FromSockAddr failed on netmask";
}
}
FillPolicy(src.address(), &info);
}
freeifaddrs(addrs);
close(ioctl_socket);
#endif
}
void AddressSorterPosix::FillPolicy(const IPAddressNumber& address,
SourceAddressInfo* info) const {
DCHECK(CalledOnValidThread());
info->scope = GetScope(ipv4_scope_table_, address);
info->label = GetPolicyValue(label_table_, address);
}
// static
scoped_ptr<AddressSorter> AddressSorter::CreateAddressSorter() {
return scoped_ptr<AddressSorter>(
new AddressSorterPosix(ClientSocketFactory::GetDefaultFactory()));
}
} // namespace net
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