src/net/base/address_tracker_linux.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/base/address_tracker_linux.h"
   6
   7 #include <errno.h>
   8 #include <linux/if.h>
   9 #include <sys/ioctl.h>
  10
  11 #include "base/logging.h"
  12 #include "base/posix/eintr_wrapper.h"
  13 #include "base/threading/thread_restrictions.h"
  14
  15 namespace net {
  16 namespace internal {
  17
  18 namespace {
  19
  20 // Retrieves address from NETLINK address message.
  21 // Sets |really_deprecated| for IPv6 addresses with preferred lifetimes of 0.
  22 bool GetAddress(const struct nlmsghdr* header,
  23                 IPAddressNumber* out,
  24                 bool* really_deprecated) {
  25   if (really_deprecated)
  26     *really_deprecated = false;
  27   const struct ifaddrmsg* msg =
  28       reinterpret_cast<struct ifaddrmsg*>(NLMSG_DATA(header));
  29   size_t address_length = 0;
  30   switch (msg->ifa_family) {
  31     case AF_INET:
  32       address_length = kIPv4AddressSize;
  33       break;
  34     case AF_INET6:
  35       address_length = kIPv6AddressSize;
  36       break;
  37     default:
  38       // Unknown family.
  39       return false;
  40   }
  41   // Use IFA_ADDRESS unless IFA_LOCAL is present. This behavior here is based on
  42   // getaddrinfo in glibc (check_pf.c). Judging from kernel implementation of
  43   // NETLINK, IPv4 addresses have only the IFA_ADDRESS attribute, while IPv6
  44   // have the IFA_LOCAL attribute.
  45   unsigned char* address = NULL;
  46   unsigned char* local = NULL;
  47   size_t length = IFA_PAYLOAD(header);
  48   for (const struct rtattr* attr =
  49            reinterpret_cast<const struct rtattr*>(IFA_RTA(msg));
  50        RTA_OK(attr, length);
  51        attr = RTA_NEXT(attr, length)) {
  52     switch (attr->rta_type) {
  53       case IFA_ADDRESS:
  54         DCHECK_GE(RTA_PAYLOAD(attr), address_length);
  55         address = reinterpret_cast<unsigned char*>(RTA_DATA(attr));
  56         break;
  57       case IFA_LOCAL:
  58         DCHECK_GE(RTA_PAYLOAD(attr), address_length);
  59         local = reinterpret_cast<unsigned char*>(RTA_DATA(attr));
  60         break;
  61       case IFA_CACHEINFO: {
  62         const struct ifa_cacheinfo *cache_info =
  63             reinterpret_cast<const struct ifa_cacheinfo*>(RTA_DATA(attr));
  64         if (really_deprecated)
  65           *really_deprecated = (cache_info->ifa_prefered == 0);
  66       } break;
  67       default:
  68         break;
  69     }
  70   }
  71   if (local)
  72     address = local;
  73   if (!address)
  74     return false;
  75   out->assign(address, address + address_length);
  76   return true;
  77 }
  78
  79 // Returns the name for the interface with interface index |interface_index|.
  80 // The return value points to a function-scoped static so it may be changed by
  81 // subsequent calls. This function could be replaced with if_indextoname() but
  82 // net/if.h cannot be mixed with linux/if.h so we'll stick with exclusively
  83 // talking to the kernel and not the C library.
  84 const char* GetInterfaceName(int interface_index) {
  85   int ioctl_socket = socket(AF_INET, SOCK_DGRAM, 0);
  86   if (ioctl_socket < 0)
  87     return "";
  88   static struct ifreq ifr;
  89   memset(&ifr, 0, sizeof(ifr));
  90   ifr.ifr_ifindex = interface_index;
  91   int rv = ioctl(ioctl_socket, SIOCGIFNAME, &ifr);
  92   close(ioctl_socket);
  93   if (rv != 0)
  94     return "";
  95   return ifr.ifr_name;
  96 }
  97
  98 }  // namespace
  99
 100 AddressTrackerLinux::AddressTrackerLinux(const base::Closure& address_callback,
 101                                          const base::Closure& link_callback,
 102                                          const base::Closure& tunnel_callback)
 103     : get_interface_name_(GetInterfaceName),
 104       address_callback_(address_callback),
 105       link_callback_(link_callback),
 106       tunnel_callback_(tunnel_callback),
 107       netlink_fd_(-1),
 108       is_offline_(true),
 109       is_offline_initialized_(false),
 110       is_offline_initialized_cv_(&is_offline_lock_) {
 111   DCHECK(!address_callback.is_null());
 112   DCHECK(!link_callback.is_null());
 113 }
 114
 115 AddressTrackerLinux::~AddressTrackerLinux() {
 116   CloseSocket();
 117 }
 118
 119 void AddressTrackerLinux::Init() {
 120   netlink_fd_ = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
 121   if (netlink_fd_ < 0) {
 122     PLOG(ERROR) << "Could not create NETLINK socket";
 123     AbortAndForceOnline();
 124     return;
 125   }
 126
 127   // Request notifications.
 128   struct sockaddr_nl addr = {};
 129   addr.nl_family = AF_NETLINK;
 130   addr.nl_pid = getpid();
 131   // TODO(szym): Track RTMGRP_LINK as well for ifi_type, http://crbug.com/113993
 132   addr.nl_groups = RTMGRP_IPV4_IFADDR | RTMGRP_IPV6_IFADDR | RTMGRP_NOTIFY |
 133       RTMGRP_LINK;
 134   int rv = bind(netlink_fd_,
 135                 reinterpret_cast<struct sockaddr*>(&addr),
 136                 sizeof(addr));
 137   if (rv < 0) {
 138     PLOG(ERROR) << "Could not bind NETLINK socket";
 139     AbortAndForceOnline();
 140     return;
 141   }
 142
 143   // Request dump of addresses.
 144   struct sockaddr_nl peer = {};
 145   peer.nl_family = AF_NETLINK;
 146
 147   struct {
 148     struct nlmsghdr header;
 149     struct rtgenmsg msg;
 150   } request = {};
 151
 152   request.header.nlmsg_len = NLMSG_LENGTH(sizeof(request.msg));
 153   request.header.nlmsg_type = RTM_GETADDR;
 154   request.header.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
 155   request.header.nlmsg_pid = getpid();
 156   request.msg.rtgen_family = AF_UNSPEC;
 157
 158   rv = HANDLE_EINTR(sendto(netlink_fd_, &request, request.header.nlmsg_len,
 159                            0, reinterpret_cast<struct sockaddr*>(&peer),
 160                            sizeof(peer)));
 161   if (rv < 0) {
 162     PLOG(ERROR) << "Could not send NETLINK request";
 163     AbortAndForceOnline();
 164     return;
 165   }
 166
 167   // Consume pending message to populate the AddressMap, but don't notify.
 168   // Sending another request without first reading responses results in EBUSY.
 169   bool address_changed;
 170   bool link_changed;
 171   bool tunnel_changed;
 172   ReadMessages(&address_changed, &link_changed, &tunnel_changed);
 173
 174   // Request dump of link state
 175   request.header.nlmsg_type = RTM_GETLINK;
 176
 177   rv = HANDLE_EINTR(sendto(netlink_fd_, &request, request.header.nlmsg_len, 0,
 178                            reinterpret_cast<struct sockaddr*>(&peer),
 179                            sizeof(peer)));
 180   if (rv < 0) {
 181     PLOG(ERROR) << "Could not send NETLINK request";
 182     AbortAndForceOnline();
 183     return;
 184   }
 185
 186   // Consume pending message to populate links_online_, but don't notify.
 187   ReadMessages(&address_changed, &link_changed, &tunnel_changed);
 188   {
 189     base::AutoLock lock(is_offline_lock_);
 190     is_offline_initialized_ = true;
 191     is_offline_initialized_cv_.Signal();
 192   }
 193
 194   rv = base::MessageLoopForIO::current()->WatchFileDescriptor(
 195       netlink_fd_, true, base::MessageLoopForIO::WATCH_READ, &watcher_, this);
 196   if (rv < 0) {
 197     PLOG(ERROR) << "Could not watch NETLINK socket";
 198     AbortAndForceOnline();
 199     return;
 200   }
 201 }
 202
 203 void AddressTrackerLinux::AbortAndForceOnline() {
 204   CloseSocket();
 205   base::AutoLock lock(is_offline_lock_);
 206   is_offline_ = false;
 207   is_offline_initialized_ = true;
 208   is_offline_initialized_cv_.Signal();
 209 }
 210
 211 AddressTrackerLinux::AddressMap AddressTrackerLinux::GetAddressMap() const {
 212   base::AutoLock lock(address_map_lock_);
 213   return address_map_;
 214 }
 215
 216 NetworkChangeNotifier::ConnectionType
 217 AddressTrackerLinux::GetCurrentConnectionType() {
 218   // http://crbug.com/125097
 219   base::ThreadRestrictions::ScopedAllowWait allow_wait;
 220   base::AutoLock lock(is_offline_lock_);
 221   // Make sure the initial offline state is set before returning.
 222   while (!is_offline_initialized_) {
 223     is_offline_initialized_cv_.Wait();
 224   }
 225   // TODO(droger): Return something more detailed than CONNECTION_UNKNOWN.
 226   // http://crbug.com/160537
 227   return is_offline_ ? NetworkChangeNotifier::CONNECTION_NONE :
 228                        NetworkChangeNotifier::CONNECTION_UNKNOWN;
 229 }
 230
 231 void AddressTrackerLinux::ReadMessages(bool* address_changed,
 232                                        bool* link_changed,
 233                                        bool* tunnel_changed) {
 234   *address_changed = false;
 235   *link_changed = false;
 236   *tunnel_changed = false;
 237   char buffer[4096];
 238   bool first_loop = true;
 239   for (;;) {
 240     int rv = HANDLE_EINTR(recv(netlink_fd_,
 241                                buffer,
 242                                sizeof(buffer),
 243                                // Block the first time through loop.
 244                                first_loop ? 0 : MSG_DONTWAIT));
 245     first_loop = false;
 246     if (rv == 0) {
 247       LOG(ERROR) << "Unexpected shutdown of NETLINK socket.";
 248       return;
 249     }
 250     if (rv < 0) {
 251       if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
 252         break;
 253       PLOG(ERROR) << "Failed to recv from netlink socket";
 254       return;
 255     }
 256     HandleMessage(buffer, rv, address_changed, link_changed, tunnel_changed);
 257   };
 258   if (*link_changed) {
 259     base::AutoLock lock(is_offline_lock_);
 260     is_offline_ = online_links_.empty();
 261   }
 262 }
 263
 264 void AddressTrackerLinux::HandleMessage(char* buffer,
 265                                         size_t length,
 266                                         bool* address_changed,
 267                                         bool* link_changed,
 268                                         bool* tunnel_changed) {
 269   DCHECK(buffer);
 270   for (struct nlmsghdr* header = reinterpret_cast<struct nlmsghdr*>(buffer);
 271        NLMSG_OK(header, length);
 272        header = NLMSG_NEXT(header, length)) {
 273     switch (header->nlmsg_type) {
 274       case NLMSG_DONE:
 275         return;
 276       case NLMSG_ERROR: {
 277         const struct nlmsgerr* msg =
 278             reinterpret_cast<struct nlmsgerr*>(NLMSG_DATA(header));
 279         LOG(ERROR) << "Unexpected netlink error " << msg->error << ".";
 280       } return;
 281       case RTM_NEWADDR: {
 282         IPAddressNumber address;
 283         bool really_deprecated;
 284         if (GetAddress(header, &address, &really_deprecated)) {
 285           base::AutoLock lock(address_map_lock_);
 286           struct ifaddrmsg* msg =
 287               reinterpret_cast<struct ifaddrmsg*>(NLMSG_DATA(header));
 288           // Routers may frequently (every few seconds) output the IPv6 ULA
 289           // prefix which can cause the linux kernel to frequently output two
 290           // back-to-back messages, one without the deprecated flag and one with
 291           // the deprecated flag but both with preferred lifetimes of 0. Avoid
 292           // interpretting this as an actual change by canonicalizing the two
 293           // messages by setting the deprecated flag based on the preferred
 294           // lifetime also.  http://crbug.com/268042
 295           if (really_deprecated)
 296             msg->ifa_flags |= IFA_F_DEPRECATED;
 297           // Only indicate change if the address is new or ifaddrmsg info has
 298           // changed.
 299           AddressMap::iterator it = address_map_.find(address);
 300           if (it == address_map_.end()) {
 301             address_map_.insert(it, std::make_pair(address, *msg));
 302             *address_changed = true;
 303           } else if (memcmp(&it->second, msg, sizeof(*msg))) {
 304             it->second = *msg;
 305             *address_changed = true;
 306           }
 307         }
 308       } break;
 309       case RTM_DELADDR: {
 310         IPAddressNumber address;
 311         if (GetAddress(header, &address, NULL)) {
 312           base::AutoLock lock(address_map_lock_);
 313           if (address_map_.erase(address))
 314             *address_changed = true;
 315         }
 316       } break;
 317       case RTM_NEWLINK: {
 318         const struct ifinfomsg* msg =
 319             reinterpret_cast<struct ifinfomsg*>(NLMSG_DATA(header));
 320         if (!(msg->ifi_flags & IFF_LOOPBACK) && (msg->ifi_flags & IFF_UP) &&
 321             (msg->ifi_flags & IFF_LOWER_UP) && (msg->ifi_flags & IFF_RUNNING)) {
 322           if (online_links_.insert(msg->ifi_index).second) {
 323             *link_changed = true;
 324             if (IsTunnelInterface(msg))
 325               *tunnel_changed = true;
 326           }
 327         } else {
 328           if (online_links_.erase(msg->ifi_index)) {
 329             *link_changed = true;
 330             if (IsTunnelInterface(msg))
 331               *tunnel_changed = true;
 332           }
 333         }
 334       } break;
 335       case RTM_DELLINK: {
 336         const struct ifinfomsg* msg =
 337             reinterpret_cast<struct ifinfomsg*>(NLMSG_DATA(header));
 338         if (online_links_.erase(msg->ifi_index)) {
 339           *link_changed = true;
 340           if (IsTunnelInterface(msg))
 341             *tunnel_changed = true;
 342         }
 343       } break;
 344       default:
 345         break;
 346     }
 347   }
 348 }
 349
 350 void AddressTrackerLinux::OnFileCanReadWithoutBlocking(int fd) {
 351   DCHECK_EQ(netlink_fd_, fd);
 352   bool address_changed;
 353   bool link_changed;
 354   bool tunnel_changed;
 355   ReadMessages(&address_changed, &link_changed, &tunnel_changed);
 356   if (address_changed)
 357     address_callback_.Run();
 358   if (link_changed)
 359     link_callback_.Run();
 360   if (tunnel_changed)
 361     tunnel_callback_.Run();
 362 }
 363
 364 void AddressTrackerLinux::OnFileCanWriteWithoutBlocking(int /* fd */) {}
 365
 366 void AddressTrackerLinux::CloseSocket() {
 367   if (netlink_fd_ >= 0 && IGNORE_EINTR(close(netlink_fd_)) < 0)
 368     PLOG(ERROR) << "Could not close NETLINK socket.";
 369   netlink_fd_ = -1;
 370 }
 371
 372 bool AddressTrackerLinux::IsTunnelInterface(const struct ifinfomsg* msg) const {
 373   // Linux kernel drivers/net/tun.c uses "tun" name prefix.
 374   return strncmp(get_interface_name_(msg->ifi_index), "tun", 3) == 0;
 375 }
 376
 377 }  // namespace internal
 378 }  // namespace net