net/dns/address_sorter_posix.cc

   1 // Copyright (c) 2012 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/address_sorter_posix.h"
   6
   7 #include <netinet/in.h>
   8
   9 #if defined(OS_MACOSX) || defined(OS_BSD)
  10 #include <sys/socket.h>  // Must be included before ifaddrs.h.
  11 #include <ifaddrs.h>
  12 #include <net/if.h>
  13 #include <netinet/in_var.h>
  14 #include <string.h>
  15 #include <sys/ioctl.h>
  16 #endif
  17
  18 #include <algorithm>
  19
  20 #include "base/logging.h"
  21 #include "base/memory/scoped_vector.h"
  22 #include "net/base/net_errors.h"
  23 #include "net/socket/client_socket_factory.h"
  24 #include "net/udp/datagram_client_socket.h"
  25
  26 #if defined(OS_LINUX)
  27 #include "net/base/address_tracker_linux.h"
  28 #endif
  29
  30 namespace net {
  31
  32 namespace {
  33
  34 // Address sorting is performed according to RFC3484 with revisions.
  35 // http://tools.ietf.org/html/draft-ietf-6man-rfc3484bis-06
  36 // Precedence and label are separate to support override through /etc/gai.conf.
  37
  38 // Returns true if |p1| should precede |p2| in the table.
  39 // Sorts table by decreasing prefix size to allow longest prefix matching.
  40 bool ComparePolicy(const AddressSorterPosix::PolicyEntry& p1,
  41                    const AddressSorterPosix::PolicyEntry& p2) {
  42   return p1.prefix_length > p2.prefix_length;
  43 }
  44
  45 // Creates sorted PolicyTable from |table| with |size| entries.
  46 AddressSorterPosix::PolicyTable LoadPolicy(
  47     AddressSorterPosix::PolicyEntry* table,
  48     size_t size) {
  49   AddressSorterPosix::PolicyTable result(table, table + size);
  50   std::sort(result.begin(), result.end(), ComparePolicy);
  51   return result;
  52 }
  53
  54 // Search |table| for matching prefix of |address|. |table| must be sorted by
  55 // descending prefix (prefix of another prefix must be later in table).
  56 unsigned GetPolicyValue(const AddressSorterPosix::PolicyTable& table,
  57                         const IPAddressNumber& address) {
  58   if (address.size() == kIPv4AddressSize)
  59     return GetPolicyValue(table, ConvertIPv4NumberToIPv6Number(address));
  60   for (unsigned i = 0; i < table.size(); ++i) {
  61     const AddressSorterPosix::PolicyEntry& entry = table[i];
  62     IPAddressNumber prefix(entry.prefix, entry.prefix + kIPv6AddressSize);
  63     if (IPNumberMatchesPrefix(address, prefix, entry.prefix_length))
  64       return entry.value;
  65   }
  66   NOTREACHED();
  67   // The last entry is the least restrictive, so assume it's default.
  68   return table.back().value;
  69 }
  70
  71 bool IsIPv6Multicast(const IPAddressNumber& address) {
  72   DCHECK_EQ(kIPv6AddressSize, address.size());
  73   return address[0] == 0xFF;
  74 }
  75
  76 AddressSorterPosix::AddressScope GetIPv6MulticastScope(
  77     const IPAddressNumber& address) {
  78   DCHECK_EQ(kIPv6AddressSize, address.size());
  79   return static_cast<AddressSorterPosix::AddressScope>(address[1] & 0x0F);
  80 }
  81
  82 bool IsIPv6Loopback(const IPAddressNumber& address) {
  83   DCHECK_EQ(kIPv6AddressSize, address.size());
  84   // IN6_IS_ADDR_LOOPBACK
  85   unsigned char kLoopback[kIPv6AddressSize] = {
  86     0, 0, 0, 0, 0, 0, 0, 0,
  87     0, 0, 0, 0, 0, 0, 0, 1,
  88   };
  89   return address == IPAddressNumber(kLoopback, kLoopback + kIPv6AddressSize);
  90 }
  91
  92 bool IsIPv6LinkLocal(const IPAddressNumber& address) {
  93   DCHECK_EQ(kIPv6AddressSize, address.size());
  94   // IN6_IS_ADDR_LINKLOCAL
  95   return (address[0] == 0xFE) && ((address[1] & 0xC0) == 0x80);
  96 }
  97
  98 bool IsIPv6SiteLocal(const IPAddressNumber& address) {
  99   DCHECK_EQ(kIPv6AddressSize, address.size());
 100   // IN6_IS_ADDR_SITELOCAL
 101   return (address[0] == 0xFE) && ((address[1] & 0xC0) == 0xC0);
 102 }
 103
 104 AddressSorterPosix::AddressScope GetScope(
 105     const AddressSorterPosix::PolicyTable& ipv4_scope_table,
 106     const IPAddressNumber& address) {
 107   if (address.size() == kIPv6AddressSize) {
 108     if (IsIPv6Multicast(address)) {
 109       return GetIPv6MulticastScope(address);
 110     } else if (IsIPv6Loopback(address) || IsIPv6LinkLocal(address)) {
 111       return AddressSorterPosix::SCOPE_LINKLOCAL;
 112     } else if (IsIPv6SiteLocal(address)) {
 113       return AddressSorterPosix::SCOPE_SITELOCAL;
 114     } else {
 115       return AddressSorterPosix::SCOPE_GLOBAL;
 116     }
 117   } else if (address.size() == kIPv4AddressSize) {
 118     return static_cast<AddressSorterPosix::AddressScope>(
 119         GetPolicyValue(ipv4_scope_table, address));
 120   } else {
 121     NOTREACHED();
 122     return AddressSorterPosix::SCOPE_NODELOCAL;
 123   }
 124 }
 125
 126 // Default policy table. RFC 3484, Section 2.1.
 127 AddressSorterPosix::PolicyEntry kDefaultPrecedenceTable[] = {
 128   // ::1/128 -- loopback
 129   { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 }, 128, 50 },
 130   // ::/0 -- any
 131   { { }, 0, 40 },
 132   // ::ffff:0:0/96 -- IPv4 mapped
 133   { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF }, 96, 35 },
 134   // 2002::/16 -- 6to4
 135   { { 0x20, 0x02, }, 16, 30 },
 136   // 2001::/32 -- Teredo
 137   { { 0x20, 0x01, 0, 0 }, 32, 5 },
 138   // fc00::/7 -- unique local address
 139   { { 0xFC }, 7, 3 },
 140   // ::/96 -- IPv4 compatible
 141   { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, 96, 1 },
 142   // fec0::/10 -- site-local expanded scope
 143   { { 0xFE, 0xC0 }, 10, 1 },
 144   // 3ffe::/16 -- 6bone
 145   { { 0x3F, 0xFE }, 16, 1 },
 146 };
 147
 148 AddressSorterPosix::PolicyEntry kDefaultLabelTable[] = {
 149   // ::1/128 -- loopback
 150   { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 }, 128, 0 },
 151   // ::/0 -- any
 152   { { }, 0, 1 },
 153   // ::ffff:0:0/96 -- IPv4 mapped
 154   { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF }, 96, 4 },
 155   // 2002::/16 -- 6to4
 156   { { 0x20, 0x02, }, 16, 2 },
 157   // 2001::/32 -- Teredo
 158   { { 0x20, 0x01, 0, 0 }, 32, 5 },
 159   // fc00::/7 -- unique local address
 160   { { 0xFC }, 7, 13 },
 161   // ::/96 -- IPv4 compatible
 162   { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, 96, 3 },
 163   // fec0::/10 -- site-local expanded scope
 164   { { 0xFE, 0xC0 }, 10, 11 },
 165   // 3ffe::/16 -- 6bone
 166   { { 0x3F, 0xFE }, 16, 12 },
 167 };
 168
 169 // Default mapping of IPv4 addresses to scope.
 170 AddressSorterPosix::PolicyEntry kDefaultIPv4ScopeTable[] = {
 171   { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF, 0x7F }, 104,
 172       AddressSorterPosix::SCOPE_LINKLOCAL },
 173   { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF, 0xA9, 0xFE }, 112,
 174       AddressSorterPosix::SCOPE_LINKLOCAL },
 175   { { }, 0, AddressSorterPosix::SCOPE_GLOBAL },
 176 };
 177
 178 struct DestinationInfo {
 179   IPAddressNumber address;
 180   AddressSorterPosix::AddressScope scope;
 181   unsigned precedence;
 182   unsigned label;
 183   const AddressSorterPosix::SourceAddressInfo* src;
 184   unsigned common_prefix_length;
 185 };
 186
 187 // Returns true iff |dst_a| should precede |dst_b| in the address list.
 188 // RFC 3484, section 6.
 189 bool CompareDestinations(const DestinationInfo* dst_a,
 190                          const DestinationInfo* dst_b) {
 191   // Rule 1: Avoid unusable destinations.
 192   // Unusable destinations are already filtered out.
 193   DCHECK(dst_a->src);
 194   DCHECK(dst_b->src);
 195
 196   // Rule 2: Prefer matching scope.
 197   bool scope_match1 = (dst_a->src->scope == dst_a->scope);
 198   bool scope_match2 = (dst_b->src->scope == dst_b->scope);
 199   if (scope_match1 != scope_match2)
 200     return scope_match1;
 201
 202   // Rule 3: Avoid deprecated addresses.
 203   if (dst_a->src->deprecated != dst_b->src->deprecated)
 204     return !dst_a->src->deprecated;
 205
 206   // Rule 4: Prefer home addresses.
 207   if (dst_a->src->home != dst_b->src->home)
 208     return dst_a->src->home;
 209
 210   // Rule 5: Prefer matching label.
 211   bool label_match1 = (dst_a->src->label == dst_a->label);
 212   bool label_match2 = (dst_b->src->label == dst_b->label);
 213   if (label_match1 != label_match2)
 214     return label_match1;
 215
 216   // Rule 6: Prefer higher precedence.
 217   if (dst_a->precedence != dst_b->precedence)
 218     return dst_a->precedence > dst_b->precedence;
 219
 220   // Rule 7: Prefer native transport.
 221   if (dst_a->src->native != dst_b->src->native)
 222     return dst_a->src->native;
 223
 224   // Rule 8: Prefer smaller scope.
 225   if (dst_a->scope != dst_b->scope)
 226     return dst_a->scope < dst_b->scope;
 227
 228   // Rule 9: Use longest matching prefix. Only for matching address families.
 229   if (dst_a->address.size() == dst_b->address.size()) {
 230     if (dst_a->common_prefix_length != dst_b->common_prefix_length)
 231       return dst_a->common_prefix_length > dst_b->common_prefix_length;
 232   }
 233
 234   // Rule 10: Leave the order unchanged.
 235   // stable_sort takes care of that.
 236   return false;
 237 }
 238
 239 }  // namespace
 240
 241 AddressSorterPosix::AddressSorterPosix(ClientSocketFactory* socket_factory)
 242     : socket_factory_(socket_factory),
 243       precedence_table_(LoadPolicy(kDefaultPrecedenceTable,
 244                                    arraysize(kDefaultPrecedenceTable))),
 245       label_table_(LoadPolicy(kDefaultLabelTable,
 246                               arraysize(kDefaultLabelTable))),
 247       ipv4_scope_table_(LoadPolicy(kDefaultIPv4ScopeTable,
 248                               arraysize(kDefaultIPv4ScopeTable))) {
 249   NetworkChangeNotifier::AddIPAddressObserver(this);
 250   OnIPAddressChanged();
 251 }
 252
 253 AddressSorterPosix::~AddressSorterPosix() {
 254   NetworkChangeNotifier::RemoveIPAddressObserver(this);
 255 }
 256
 257 void AddressSorterPosix::Sort(const AddressList& list,
 258                               const CallbackType& callback) const {
 259   DCHECK(CalledOnValidThread());
 260   ScopedVector<DestinationInfo> sort_list;
 261
 262   for (size_t i = 0; i < list.size(); ++i) {
 263     scoped_ptr<DestinationInfo> info(new DestinationInfo());
 264     info->address = list[i].address();
 265     info->scope = GetScope(ipv4_scope_table_, info->address);
 266     info->precedence = GetPolicyValue(precedence_table_, info->address);
 267     info->label = GetPolicyValue(label_table_, info->address);
 268
 269     // Each socket can only be bound once.
 270     scoped_ptr<DatagramClientSocket> socket(
 271         socket_factory_->CreateDatagramClientSocket(
 272             DatagramSocket::DEFAULT_BIND,
 273             RandIntCallback(),
 274             NULL /* NetLog */,
 275             NetLog::Source()));
 276
 277     // Even though no packets are sent, cannot use port 0 in Connect.
 278     IPEndPoint dest(info->address, 80 /* port */);
 279     int rv = socket->Connect(dest);
 280     if (rv != OK) {
 281       VLOG(1) << "Could not connect to " << dest.ToStringWithoutPort()
 282               << " reason " << rv;
 283       continue;
 284     }
 285     // Filter out unusable destinations.
 286     IPEndPoint src;
 287     rv = socket->GetLocalAddress(&src);
 288     if (rv != OK) {
 289       LOG(WARNING) << "Could not get local address for "
 290                    << dest.ToStringWithoutPort() << " reason " << rv;
 291       continue;
 292     }
 293
 294     SourceAddressInfo& src_info = source_map_[src.address()];
 295     if (src_info.scope == SCOPE_UNDEFINED) {
 296       // If |source_info_| is out of date, |src| might be missing, but we still
 297       // want to sort, even though the HostCache will be cleared soon.
 298       FillPolicy(src.address(), &src_info);
 299     }
 300     info->src = &src_info;
 301
 302     if (info->address.size() == src.address().size()) {
 303       info->common_prefix_length = std::min(
 304           CommonPrefixLength(info->address, src.address()),
 305           info->src->prefix_length);
 306     }
 307     sort_list.push_back(info.Pass());
 308   }
 309
 310   std::stable_sort(sort_list.begin(), sort_list.end(), CompareDestinations);
 311
 312   AddressList result;
 313   for (size_t i = 0; i < sort_list.size(); ++i)
 314     result.push_back(IPEndPoint(sort_list[i]->address, 0 /* port */));
 315
 316   callback.Run(true, result);
 317 }
 318
 319 void AddressSorterPosix::OnIPAddressChanged() {
 320   DCHECK(CalledOnValidThread());
 321   source_map_.clear();
 322 #if defined(OS_LINUX)
 323   const internal::AddressTrackerLinux* tracker =
 324       NetworkChangeNotifier::GetAddressTracker();
 325   if (!tracker)
 326     return;
 327   typedef internal::AddressTrackerLinux::AddressMap AddressMap;
 328   AddressMap map = tracker->GetAddressMap();
 329   for (AddressMap::const_iterator it = map.begin(); it != map.end(); ++it) {
 330     const IPAddressNumber& address = it->first;
 331     const struct ifaddrmsg& msg = it->second;
 332     SourceAddressInfo& info = source_map_[address];
 333     info.native = false;  // TODO(szym): obtain this via netlink.
 334     info.deprecated = msg.ifa_flags & IFA_F_DEPRECATED;
 335     info.home = msg.ifa_flags & IFA_F_HOMEADDRESS;
 336     info.prefix_length = msg.ifa_prefixlen;
 337     FillPolicy(address, &info);
 338   }
 339 #elif defined(OS_MACOSX) || defined(OS_BSD)
 340   // It's not clear we will receive notification when deprecated flag changes.
 341   // Socket for ioctl.
 342   int ioctl_socket = socket(AF_INET6, SOCK_DGRAM, 0);
 343   if (ioctl_socket < 0)
 344     return;
 345
 346   struct ifaddrs* addrs;
 347   int rv = getifaddrs(&addrs);
 348   if (rv < 0) {
 349     LOG(WARNING) << "getifaddrs failed " << rv;
 350     close(ioctl_socket);
 351     return;
 352   }
 353
 354   for (struct ifaddrs* ifa = addrs; ifa != NULL; ifa = ifa->ifa_next) {
 355     IPEndPoint src;
 356     if (!src.FromSockAddr(ifa->ifa_addr, ifa->ifa_addr->sa_len))
 357       continue;
 358     SourceAddressInfo& info = source_map_[src.address()];
 359     // Note: no known way to fill in |native| and |home|.
 360     info.native = info.home = info.deprecated = false;
 361     if (ifa->ifa_addr->sa_family == AF_INET6) {
 362       struct in6_ifreq ifr = {};
 363       strncpy(ifr.ifr_name, ifa->ifa_name, sizeof(ifr.ifr_name) - 1);
 364       DCHECK_LE(ifa->ifa_addr->sa_len, sizeof(ifr.ifr_ifru.ifru_addr));
 365       memcpy(&ifr.ifr_ifru.ifru_addr, ifa->ifa_addr, ifa->ifa_addr->sa_len);
 366       int rv = ioctl(ioctl_socket, SIOCGIFAFLAG_IN6, &ifr);
 367       if (rv >= 0) {
 368         info.deprecated = ifr.ifr_ifru.ifru_flags & IN6_IFF_DEPRECATED;
 369       } else {
 370         LOG(WARNING) << "SIOCGIFAFLAG_IN6 failed " << rv;
 371       }
 372     }
 373     if (ifa->ifa_netmask) {
 374       IPEndPoint netmask;
 375       if (netmask.FromSockAddr(ifa->ifa_netmask, ifa->ifa_addr->sa_len)) {
 376         info.prefix_length = MaskPrefixLength(netmask.address());
 377       } else {
 378         LOG(WARNING) << "FromSockAddr failed on netmask";
 379       }
 380     }
 381     FillPolicy(src.address(), &info);
 382   }
 383   freeifaddrs(addrs);
 384   close(ioctl_socket);
 385 #endif
 386 }
 387
 388 void AddressSorterPosix::FillPolicy(const IPAddressNumber& address,
 389                                     SourceAddressInfo* info) const {
 390   DCHECK(CalledOnValidThread());
 391   info->scope = GetScope(ipv4_scope_table_, address);
 392   info->label = GetPolicyValue(label_table_, address);
 393 }
 394
 395 // static
 396 scoped_ptr<AddressSorter> AddressSorter::CreateAddressSorter() {
 397   return scoped_ptr<AddressSorter>(
 398       new AddressSorterPosix(ClientSocketFactory::GetDefaultFactory()));
 399 }
 400
 401 }  // namespace net
 402