routing_table.cc revision c0beca55d290fe0b1c96d78cbbcf94b05c23f5a5 
1//
2// Copyright (C) 2012 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/routing_table.h"
18
19#include <arpa/inet.h>
20#include <fcntl.h>
21#include <linux/netlink.h>
22#include <linux/rtnetlink.h>
23#include <netinet/ether.h>
24#include <net/if.h>  // NOLINT - must be included after netinet/ether.h
25#include <net/if_arp.h>
26#include <string.h>
27#include <sys/socket.h>
28#include <time.h>
29#include <unistd.h>
30
31#include <memory>
32#include <string>
33
34#include <base/bind.h>
35#include <base/files/file_path.h>
36#include <base/files/file_util.h>
37#include <base/stl_util.h>
38#include <base/strings/stringprintf.h>
39
40#include "shill/ipconfig.h"
41#include "shill/logging.h"
42#include "shill/net/byte_string.h"
43#include "shill/net/rtnl_handler.h"
44#include "shill/net/rtnl_listener.h"
45#include "shill/net/rtnl_message.h"
46#include "shill/routing_table_entry.h"
47
48using base::Bind;
49using base::FilePath;
50using base::Unretained;
51using std::deque;
52using std::string;
53using std::vector;
54
55namespace shill {
56
57namespace Logging {
58static auto kModuleLogScope = ScopeLogger::kRoute;
59static string ObjectID(RoutingTable* r) { return "(routing_table)"; }
60}
61
62namespace {
63base::LazyInstance<RoutingTable> g_routing_table = LAZY_INSTANCE_INITIALIZER;
64}  // namespace
65
66// static
67const char RoutingTable::kRouteFlushPath4[] = "/proc/sys/net/ipv4/route/flush";
68// static
69const char RoutingTable::kRouteFlushPath6[] = "/proc/sys/net/ipv6/route/flush";
70
71RoutingTable::RoutingTable()
72    : route_callback_(Bind(&RoutingTable::RouteMsgHandler, Unretained(this))),
73      rtnl_handler_(RTNLHandler::GetInstance()) {
74  SLOG(this, 2) << __func__;
75}
76
77RoutingTable::~RoutingTable() {}
78
79RoutingTable* RoutingTable::GetInstance() {
80  return g_routing_table.Pointer();
81}
82
83void RoutingTable::Start() {
84  SLOG(this, 2) << __func__;
85
86  route_listener_.reset(
87      new RTNLListener(RTNLHandler::kRequestRoute, route_callback_));
88  rtnl_handler_->RequestDump(RTNLHandler::kRequestRoute);
89}
90
91void RoutingTable::Stop() {
92  SLOG(this, 2) << __func__;
93
94  route_listener_.reset();
95}
96
97bool RoutingTable::AddRoute(int interface_index,
98                            const RoutingTableEntry& entry) {
99  SLOG(this, 2) << __func__ << ": "
100                << "destination " << entry.dst.ToString()
101                << " index " << interface_index
102                << " gateway " << entry.gateway.ToString()
103                << " metric " << entry.metric;
104
105  CHECK(!entry.from_rtnl);
106  if (!ApplyRoute(interface_index,
107                  entry,
108                  RTNLMessage::kModeAdd,
109                  NLM_F_CREATE | NLM_F_EXCL)) {
110    return false;
111  }
112  tables_[interface_index].push_back(entry);
113  return true;
114}
115
116bool RoutingTable::GetDefaultRoute(int interface_index,
117                                   IPAddress::Family family,
118                                   RoutingTableEntry* entry) {
119  RoutingTableEntry* found_entry;
120  bool ret = GetDefaultRouteInternal(interface_index, family, &found_entry);
121  if (ret) {
122    *entry = *found_entry;
123  }
124  return ret;
125}
126
127bool RoutingTable::GetDefaultRouteInternal(int interface_index,
128                                           IPAddress::Family family,
129                                           RoutingTableEntry** entry) {
130  SLOG(this, 2) << __func__ << " index " << interface_index
131                << " family " << IPAddress::GetAddressFamilyName(family);
132
133  Tables::iterator table = tables_.find(interface_index);
134  if (table == tables_.end()) {
135    SLOG(this, 2) << __func__ << " no table";
136    return false;
137  }
138
139  for (auto& nent : table->second) {
140    if (nent.dst.IsDefault() && nent.dst.family() == family) {
141      *entry = &nent;
142      SLOG(this, 2) << __func__ << ": found"
143                    << " gateway " << nent.gateway.ToString()
144                    << " metric " << nent.metric;
145      return true;
146    }
147  }
148
149  SLOG(this, 2) << __func__ << " no route";
150  return false;
151}
152
153bool RoutingTable::SetDefaultRoute(int interface_index,
154                                   const IPAddress& gateway_address,
155                                   uint32_t metric,
156                                   uint8_t table_id) {
157  SLOG(this, 2) << __func__ << " index " << interface_index
158                << " metric " << metric;
159
160  RoutingTableEntry* old_entry;
161
162  if (GetDefaultRouteInternal(interface_index,
163                              gateway_address.family(),
164                              &old_entry)) {
165    if (old_entry->gateway.Equals(gateway_address)) {
166      if (old_entry->metric != metric) {
167        ReplaceMetric(interface_index, old_entry, metric);
168      }
169      return true;
170    } else {
171      // TODO(quiche): Update internal state as well?
172      ApplyRoute(interface_index,
173                 *old_entry,
174                 RTNLMessage::kModeDelete,
175                 0);
176    }
177  }
178
179  IPAddress default_address(gateway_address.family());
180  default_address.SetAddressToDefault();
181
182  return AddRoute(interface_index,
183                  RoutingTableEntry(default_address,
184                                    default_address,
185                                    gateway_address,
186                                    metric,
187                                    RT_SCOPE_UNIVERSE,
188                                    false,
189                                    table_id,
190                                    RoutingTableEntry::kDefaultTag));
191}
192
193bool RoutingTable::ConfigureRoutes(int interface_index,
194                                   const IPConfigRefPtr& ipconfig,
195                                   uint32_t metric,
196                                   uint8_t table_id) {
197  bool ret = true;
198
199  IPAddress::Family address_family = ipconfig->properties().address_family;
200  const vector<IPConfig::Route>& routes = ipconfig->properties().routes;
201
202  for (const auto& route : routes) {
203    SLOG(this, 3) << "Installing route:"
204                  << " Destination: " << route.host
205                  << " Netmask: " << route.netmask
206                  << " Gateway: " << route.gateway;
207    IPAddress destination_address(address_family);
208    IPAddress source_address(address_family);  // Left as default.
209    IPAddress gateway_address(address_family);
210    if (!destination_address.SetAddressFromString(route.host)) {
211      LOG(ERROR) << "Failed to parse host "
212                 << route.host;
213      ret = false;
214      continue;
215    }
216    if (!gateway_address.SetAddressFromString(route.gateway)) {
217      LOG(ERROR) << "Failed to parse gateway "
218                 << route.gateway;
219      ret = false;
220      continue;
221    }
222    destination_address.set_prefix(
223        IPAddress::GetPrefixLengthFromMask(address_family, route.netmask));
224    if (!AddRoute(interface_index,
225                  RoutingTableEntry(destination_address,
226                                    source_address,
227                                    gateway_address,
228                                    metric,
229                                    RT_SCOPE_UNIVERSE,
230                                    false,
231                                    table_id,
232                                    RoutingTableEntry::kDefaultTag))) {
233      ret = false;
234    }
235  }
236  return ret;
237}
238
239void RoutingTable::FlushRoutes(int interface_index) {
240  SLOG(this, 2) << __func__;
241
242  auto table = tables_.find(interface_index);
243  if (table == tables_.end()) {
244    return;
245  }
246
247  for (const auto& nent : table->second) {
248    ApplyRoute(interface_index, nent, RTNLMessage::kModeDelete, 0);
249  }
250  table->second.clear();
251}
252
253void RoutingTable::FlushRoutesWithTag(int tag) {
254  SLOG(this, 2) << __func__;
255
256  for (auto& table : tables_) {
257    for (auto nent = table.second.begin(); nent != table.second.end();) {
258      if (nent->tag == tag) {
259        ApplyRoute(table.first, *nent, RTNLMessage::kModeDelete, 0);
260        nent = table.second.erase(nent);
261      } else {
262        ++nent;
263      }
264    }
265  }
266}
267
268void RoutingTable::ResetTable(int interface_index) {
269  tables_.erase(interface_index);
270}
271
272void RoutingTable::SetDefaultMetric(int interface_index, uint32_t metric) {
273  SLOG(this, 2) << __func__ << " index " << interface_index
274                << " metric " << metric;
275
276  RoutingTableEntry* entry;
277  if (GetDefaultRouteInternal(
278          interface_index, IPAddress::kFamilyIPv4, &entry) &&
279      entry->metric != metric) {
280    ReplaceMetric(interface_index, entry, metric);
281  }
282
283  if (GetDefaultRouteInternal(
284          interface_index, IPAddress::kFamilyIPv6, &entry) &&
285      entry->metric != metric) {
286    ReplaceMetric(interface_index, entry, metric);
287  }
288}
289
290// static
291bool RoutingTable::ParseRoutingTableMessage(const RTNLMessage& message,
292                                            int* interface_index,
293                                            RoutingTableEntry* entry) {
294  if (message.type() != RTNLMessage::kTypeRoute ||
295      message.family() == IPAddress::kFamilyUnknown ||
296      !message.HasAttribute(RTA_OIF)) {
297    return false;
298  }
299
300  const RTNLMessage::RouteStatus& route_status = message.route_status();
301
302  if (route_status.type != RTN_UNICAST) {
303    return false;
304  }
305
306  uint32_t interface_index_u32 = 0;
307  if (!message.GetAttribute(RTA_OIF).ConvertToCPUUInt32(&interface_index_u32)) {
308    return false;
309  }
310  *interface_index = interface_index_u32;
311
312  uint32_t metric = 0;
313  if (message.HasAttribute(RTA_PRIORITY)) {
314    message.GetAttribute(RTA_PRIORITY).ConvertToCPUUInt32(&metric);
315  }
316
317  IPAddress default_addr(message.family());
318  default_addr.SetAddressToDefault();
319
320  ByteString dst_bytes(default_addr.address());
321  if (message.HasAttribute(RTA_DST)) {
322    dst_bytes = message.GetAttribute(RTA_DST);
323  }
324  ByteString src_bytes(default_addr.address());
325  if (message.HasAttribute(RTA_SRC)) {
326    src_bytes = message.GetAttribute(RTA_SRC);
327  }
328  ByteString gateway_bytes(default_addr.address());
329  if (message.HasAttribute(RTA_GATEWAY)) {
330    gateway_bytes = message.GetAttribute(RTA_GATEWAY);
331  }
332
333  entry->dst = IPAddress(message.family(), dst_bytes, route_status.dst_prefix);
334  entry->src = IPAddress(message.family(), src_bytes, route_status.src_prefix);
335  entry->gateway = IPAddress(message.family(), gateway_bytes);
336  entry->metric = metric;
337  entry->scope = route_status.scope;
338  entry->from_rtnl = true;
339  entry->table = route_status.table;
340
341  return true;
342}
343
344void RoutingTable::RouteMsgHandler(const RTNLMessage& message) {
345  int interface_index;
346  RoutingTableEntry entry;
347
348  if (!ParseRoutingTableMessage(message, &interface_index, &entry)) {
349    return;
350  }
351
352  if (!route_queries_.empty() &&
353      message.route_status().protocol == RTPROT_UNSPEC) {
354    SLOG(this, 3) << __func__ << ": Message seq: " << message.seq()
355                  << " mode " << message.mode()
356                  << ", next query seq: " << route_queries_.front().sequence;
357
358    // Purge queries that have expired (sequence number of this message is
359    // greater than that of the head of the route query sequence).  Do the
360    // math in a way that's roll-over independent.
361    while (route_queries_.front().sequence - message.seq() > kuint32max / 2) {
362      LOG(ERROR) << __func__ << ": Purging un-replied route request sequence "
363                 << route_queries_.front().sequence
364                 << " (< " << message.seq() << ")";
365      route_queries_.pop_front();
366      if (route_queries_.empty())
367        return;
368    }
369
370    const Query& query = route_queries_.front();
371    if (query.sequence == message.seq()) {
372      RoutingTableEntry add_entry(entry);
373      add_entry.from_rtnl = false;
374      add_entry.tag = query.tag;
375      add_entry.table = query.table_id;
376      bool added = true;
377      if (add_entry.gateway.IsDefault()) {
378        SLOG(this, 2) << __func__ << ": Ignoring route result with no gateway "
379                      << "since we don't need to plumb these.";
380      } else {
381        SLOG(this, 2) << __func__ << ": Adding host route to "
382                      << add_entry.dst.ToString();
383        added = AddRoute(interface_index, add_entry);
384      }
385      if (added && !query.callback.is_null()) {
386        SLOG(this, 2) << "Running query callback.";
387        query.callback.Run(interface_index, add_entry);
388      }
389      route_queries_.pop_front();
390    }
391    return;
392  } else if (message.route_status().protocol != RTPROT_BOOT) {
393    // Responses to route queries come back with a protocol of
394    // RTPROT_UNSPEC.  Otherwise, normal route updates that we are
395    // interested in come with a protocol of RTPROT_BOOT.
396    return;
397  }
398
399  TableEntryVector& table = tables_[interface_index];
400  for (auto nent = table.begin(); nent != table.end(); ++nent)  {
401    if (nent->dst.Equals(entry.dst) &&
402        nent->src.Equals(entry.src) &&
403        nent->gateway.Equals(entry.gateway) &&
404        nent->scope == entry.scope) {
405      if (message.mode() == RTNLMessage::kModeDelete &&
406          nent->metric == entry.metric) {
407        table.erase(nent);
408      } else if (message.mode() == RTNLMessage::kModeAdd) {
409        nent->from_rtnl = true;
410        nent->metric = entry.metric;
411      }
412      return;
413    }
414  }
415
416  if (message.mode() == RTNLMessage::kModeAdd) {
417    SLOG(this, 2) << __func__ << " adding"
418                  << " destination " << entry.dst.ToString()
419                  << " index " << interface_index
420                  << " gateway " << entry.gateway.ToString()
421                  << " metric " << entry.metric;
422    table.push_back(entry);
423  }
424}
425
426bool RoutingTable::ApplyRoute(uint32_t interface_index,
427                              const RoutingTableEntry& entry,
428                              RTNLMessage::Mode mode,
429                              unsigned int flags) {
430  SLOG(this, 2) << base::StringPrintf(
431      "%s: dst %s/%d src %s/%d index %d mode %d flags 0x%x",
432      __func__, entry.dst.ToString().c_str(), entry.dst.prefix(),
433      entry.src.ToString().c_str(), entry.src.prefix(),
434      interface_index, mode, flags);
435
436  RTNLMessage message(
437      RTNLMessage::kTypeRoute,
438      mode,
439      NLM_F_REQUEST | flags,
440      0,
441      0,
442      0,
443      entry.dst.family());
444
445  message.set_route_status(RTNLMessage::RouteStatus(
446      entry.dst.prefix(),
447      entry.src.prefix(),
448      entry.table,
449      RTPROT_BOOT,
450      entry.scope,
451      RTN_UNICAST,
452      0));
453
454  message.SetAttribute(RTA_DST, entry.dst.address());
455  if (!entry.src.IsDefault()) {
456    message.SetAttribute(RTA_SRC, entry.src.address());
457  }
458  if (!entry.gateway.IsDefault()) {
459    message.SetAttribute(RTA_GATEWAY, entry.gateway.address());
460  }
461  message.SetAttribute(RTA_PRIORITY,
462                       ByteString::CreateFromCPUUInt32(entry.metric));
463  message.SetAttribute(RTA_OIF,
464                       ByteString::CreateFromCPUUInt32(interface_index));
465
466  return rtnl_handler_->SendMessage(&message);
467}
468
469// Somewhat surprisingly, the kernel allows you to create multiple routes
470// to the same destination through the same interface with different metrics.
471// Therefore, to change the metric on a route, we can't just use the
472// NLM_F_REPLACE flag by itself.  We have to explicitly remove the old route.
473// We do so after creating the route at a new metric so there is no traffic
474// disruption to existing network streams.
475void RoutingTable::ReplaceMetric(uint32_t interface_index,
476                                 RoutingTableEntry* entry,
477                                 uint32_t metric) {
478  SLOG(this, 2) << __func__ << " index " << interface_index
479                << " metric " << metric;
480  RoutingTableEntry new_entry = *entry;
481  new_entry.metric = metric;
482  // First create the route at the new metric.
483  ApplyRoute(interface_index, new_entry, RTNLMessage::kModeAdd,
484             NLM_F_CREATE | NLM_F_REPLACE);
485  // Then delete the route at the old metric.
486  ApplyRoute(interface_index, *entry, RTNLMessage::kModeDelete, 0);
487  // Now, update our routing table (via |*entry|) from |new_entry|.
488  *entry = new_entry;
489}
490
491bool RoutingTable::FlushCache() {
492  static const char* kPaths[2] = { kRouteFlushPath4, kRouteFlushPath6 };
493  bool ret = true;
494
495  SLOG(this, 2) << __func__;
496
497  for (size_t i = 0; i < arraysize(kPaths); ++i) {
498    if (base::WriteFile(FilePath(kPaths[i]), "-1", 2) != 2) {
499      LOG(ERROR) << base::StringPrintf("Cannot write to route flush file %s",
500                                       kPaths[i]);
501      ret = false;
502    }
503  }
504
505  return ret;
506}
507
508bool RoutingTable::RequestRouteToHost(const IPAddress& address,
509                                      int interface_index,
510                                      int tag,
511                                      const Query::Callback& callback,
512                                      uint8_t table_id) {
513  // Make sure we don't get a cached response that is no longer valid.
514  FlushCache();
515
516  RTNLMessage message(
517      RTNLMessage::kTypeRoute,
518      RTNLMessage::kModeQuery,
519      NLM_F_REQUEST,
520      0,
521      0,
522      interface_index,
523      address.family());
524
525  RTNLMessage::RouteStatus status;
526  status.dst_prefix = address.prefix();
527  message.set_route_status(status);
528  message.SetAttribute(RTA_DST, address.address());
529
530  if (interface_index != -1) {
531    message.SetAttribute(RTA_OIF,
532                         ByteString::CreateFromCPUUInt32(interface_index));
533  }
534
535  if (!rtnl_handler_->SendMessage(&message)) {
536    return false;
537  }
538
539  // Save the sequence number of the request so we can create a route for
540  // this host when we get a reply.
541  route_queries_.push_back(Query(message.seq(), tag, callback, table_id));
542
543  return true;
544}
545
546bool RoutingTable::CreateBlackholeRoute(int interface_index,
547                                        IPAddress::Family family,
548                                        uint32_t metric,
549                                        uint8_t table_id) {
550  SLOG(this, 2) << base::StringPrintf(
551      "%s: index %d family %s metric %d",
552      __func__, interface_index,
553      IPAddress::GetAddressFamilyName(family).c_str(), metric);
554
555  RTNLMessage message(
556      RTNLMessage::kTypeRoute,
557      RTNLMessage::kModeAdd,
558      NLM_F_REQUEST | NLM_F_CREATE | NLM_F_EXCL,
559      0,
560      0,
561      0,
562      family);
563
564  message.set_route_status(RTNLMessage::RouteStatus(
565      0,
566      0,
567      table_id,
568      RTPROT_BOOT,
569      RT_SCOPE_UNIVERSE,
570      RTN_BLACKHOLE,
571      0));
572
573  message.SetAttribute(RTA_PRIORITY,
574                       ByteString::CreateFromCPUUInt32(metric));
575  message.SetAttribute(RTA_OIF,
576                       ByteString::CreateFromCPUUInt32(interface_index));
577
578  return rtnl_handler_->SendMessage(&message);
579}
580
581bool RoutingTable::CreateLinkRoute(int interface_index,
582                                   const IPAddress& local_address,
583                                   const IPAddress& remote_address,
584                                   uint8_t table_id) {
585  if (!local_address.CanReachAddress(remote_address)) {
586    LOG(ERROR) << __func__ << " failed: "
587               << remote_address.ToString() << " is not reachable from "
588               << local_address.ToString();
589    return false;
590  }
591
592  IPAddress default_address(local_address.family());
593  default_address.SetAddressToDefault();
594  IPAddress destination_address(remote_address);
595  destination_address.set_prefix(
596      IPAddress::GetMaxPrefixLength(remote_address.family()));
597  SLOG(this, 2) << "Creating link route to " << destination_address.ToString()
598                << " from " << local_address.ToString()
599                << " on interface index " << interface_index;
600  return AddRoute(interface_index,
601                  RoutingTableEntry(destination_address,
602                                    local_address,
603                                    default_address,
604                                    0,
605                                    RT_SCOPE_LINK,
606                                    false,
607                                    table_id,
608                                    RoutingTableEntry::kDefaultTag));
609}
610
611}  // namespace shill
612