routing_table.cc revision fad4a0b7e55dd82d3815ee96862b6e546727eb6e 
1// Copyright (c) 2012 The Chromium OS 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 "shill/routing_table.h"
6
7#include <arpa/inet.h>
8#include <fcntl.h>
9#include <linux/netlink.h>
10#include <linux/rtnetlink.h>
11#include <netinet/ether.h>
12#include <net/if.h>
13#include <net/if_arp.h>
14#include <string.h>
15#include <sys/socket.h>
16#include <time.h>
17#include <unistd.h>
18
19#include <string>
20
21#include <base/bind.h>
22#include <base/file_path.h>
23#include <base/file_util.h>
24#include <base/hash_tables.h>
25#include <base/logging.h>
26#include <base/memory/scoped_ptr.h>
27#include <base/stl_util.h>
28#include <base/stringprintf.h>
29
30#include "shill/byte_string.h"
31#include "shill/routing_table_entry.h"
32#include "shill/rtnl_handler.h"
33#include "shill/rtnl_listener.h"
34#include "shill/rtnl_message.h"
35#include "shill/scope_logger.h"
36
37using base::Bind;
38using base::Unretained;
39using std::string;
40using std::vector;
41
42namespace shill {
43
44// TODO(ers): not using LAZY_INSTANCE_INITIALIZER
45// because of http://crbug.com/114828
46static base::LazyInstance<RoutingTable> g_routing_table = {0, {{0}}};
47
48// static
49const char RoutingTable::kRouteFlushPath4[] = "/proc/sys/net/ipv4/route/flush";
50// static
51const char RoutingTable::kRouteFlushPath6[] = "/proc/sys/net/ipv6/route/flush";
52
53RoutingTable::RoutingTable()
54    : route_callback_(Bind(&RoutingTable::RouteMsgHandler, Unretained(this))),
55      route_listener_(NULL),
56      rtnl_handler_(RTNLHandler::GetInstance()) {
57  SLOG(Route, 2) << __func__;
58}
59
60RoutingTable::~RoutingTable() {}
61
62RoutingTable* RoutingTable::GetInstance() {
63  return g_routing_table.Pointer();
64}
65
66void RoutingTable::Start() {
67  SLOG(Route, 2) << __func__;
68
69  route_listener_.reset(
70      new RTNLListener(RTNLHandler::kRequestRoute, route_callback_));
71  rtnl_handler_->RequestDump(RTNLHandler::kRequestRoute);
72}
73
74void RoutingTable::Stop() {
75  SLOG(Route, 2) << __func__;
76
77  route_listener_.reset();
78}
79
80bool RoutingTable::AddRoute(int interface_index,
81                            const RoutingTableEntry &entry) {
82  SLOG(Route, 2) << __func__ << ": "
83                 << "destination " << entry.dst.ToString()
84                 << " index " << interface_index
85                 << " gateway " << entry.gateway.ToString()
86                 << " metric " << entry.metric;
87
88  CHECK(!entry.from_rtnl);
89  if (!ApplyRoute(interface_index,
90                  entry,
91                  RTNLMessage::kModeAdd,
92                  NLM_F_CREATE | NLM_F_EXCL)) {
93    return false;
94  }
95  tables_[interface_index].push_back(entry);
96  return true;
97}
98
99bool RoutingTable::GetDefaultRoute(int interface_index,
100                                   IPAddress::Family family,
101                                   RoutingTableEntry *entry) {
102  RoutingTableEntry *found_entry;
103  bool ret = GetDefaultRouteInternal(interface_index, family, &found_entry);
104  if (ret) {
105    *entry = *found_entry;
106  }
107  return ret;
108}
109
110bool RoutingTable::GetDefaultRouteInternal(int interface_index,
111                                           IPAddress::Family family,
112                                           RoutingTableEntry **entry) {
113  SLOG(Route, 2) << __func__ << " index " << interface_index
114                 << " family " << IPAddress::GetAddressFamilyName(family);
115
116  base::hash_map<int, vector<RoutingTableEntry> >::iterator table =
117    tables_.find(interface_index);
118
119  if (table == tables_.end()) {
120    SLOG(Route, 2) << __func__ << " no table";
121    return false;
122  }
123
124  vector<RoutingTableEntry>::iterator nent;
125
126  for (nent = table->second.begin(); nent != table->second.end(); ++nent) {
127    if (nent->dst.IsDefault() && nent->dst.family() == family) {
128      *entry = &(*nent);
129      SLOG(Route, 2) << __func__ << ": found"
130                     << " gateway " << nent->gateway.ToString()
131                     << " metric " << nent->metric;
132      return true;
133    }
134  }
135
136  SLOG(Route, 2) << __func__ << " no route";
137  return false;
138}
139
140bool RoutingTable::SetDefaultRoute(int interface_index,
141                                   const IPAddress &gateway_address,
142                                   uint32 metric) {
143  SLOG(Route, 2) << __func__ << " index " << interface_index
144                 << " metric " << metric;
145
146  RoutingTableEntry *old_entry;
147
148  if (GetDefaultRouteInternal(interface_index,
149                              gateway_address.family(),
150                              &old_entry)) {
151    if (old_entry->gateway.Equals(gateway_address)) {
152      if (old_entry->metric != metric) {
153        ReplaceMetric(interface_index, old_entry, metric);
154      }
155      return true;
156    } else {
157      // TODO(quiche): Update internal state as well?
158      ApplyRoute(interface_index,
159                 *old_entry,
160                 RTNLMessage::kModeDelete,
161                 0);
162    }
163  }
164
165  IPAddress default_address(gateway_address.family());
166  default_address.SetAddressToDefault();
167
168  return AddRoute(interface_index,
169                  RoutingTableEntry(default_address,
170                                    default_address,
171                                    gateway_address,
172                                    metric,
173                                    RT_SCOPE_UNIVERSE,
174                                    false));
175}
176
177bool RoutingTable::ConfigureRoutes(int interface_index,
178                                   const IPConfigRefPtr &ipconfig,
179                                   uint32 metric) {
180  bool ret = true;
181
182  IPAddress::Family address_family = ipconfig->properties().address_family;
183  const vector<IPConfig::Route> &routes = ipconfig->properties().routes;
184
185  for (vector<IPConfig::Route>::const_iterator it = routes.begin();
186       it != routes.end();
187       ++it) {
188    SLOG(Route, 3) << "Installing route:"
189                   << " Destination: " << it->host
190                   << " Netmask: " << it->netmask
191                   << " Gateway: " << it->gateway;
192    IPAddress destination_address(address_family);
193    IPAddress source_address(address_family);  // Left as default.
194    IPAddress gateway_address(address_family);
195    if (!destination_address.SetAddressFromString(it->host)) {
196      LOG(ERROR) << "Failed to parse host "
197                 << it->host;
198      ret = false;
199      continue;
200    }
201    if (!gateway_address.SetAddressFromString(it->gateway)) {
202      LOG(ERROR) << "Failed to parse gateway "
203                 << it->gateway;
204      ret = false;
205      continue;
206    }
207    destination_address.set_prefix(
208        IPAddress::GetPrefixLengthFromMask(address_family, it->netmask));
209    if (!AddRoute(interface_index,
210                  RoutingTableEntry(destination_address,
211                                    source_address,
212                                    gateway_address,
213                                    metric,
214                                    RT_SCOPE_UNIVERSE,
215                                    false))) {
216      ret = false;
217    }
218  }
219  return ret;
220}
221
222void RoutingTable::FlushRoutes(int interface_index) {
223  SLOG(Route, 2) << __func__;
224
225  base::hash_map<int, vector<RoutingTableEntry> >::iterator table =
226    tables_.find(interface_index);
227
228  if (table == tables_.end()) {
229    return;
230  }
231
232  vector<RoutingTableEntry>::iterator nent;
233
234  for (nent = table->second.begin(); nent != table->second.end(); ++nent) {
235      ApplyRoute(interface_index, *nent, RTNLMessage::kModeDelete, 0);
236  }
237  table->second.clear();
238}
239
240void RoutingTable::ResetTable(int interface_index) {
241  tables_.erase(interface_index);
242}
243
244void RoutingTable::SetDefaultMetric(int interface_index, uint32 metric) {
245  SLOG(Route, 2) << __func__ << " index " << interface_index
246                 << " metric " << metric;
247
248  RoutingTableEntry *entry;
249  if (GetDefaultRouteInternal(
250          interface_index, IPAddress::kFamilyIPv4, &entry) &&
251      entry->metric != metric) {
252    ReplaceMetric(interface_index, entry, metric);
253  }
254
255  if (GetDefaultRouteInternal(
256          interface_index, IPAddress::kFamilyIPv6, &entry) &&
257      entry->metric != metric) {
258    ReplaceMetric(interface_index, entry, metric);
259  }
260}
261
262// static
263bool RoutingTable::ParseRoutingTableMessage(const RTNLMessage &message,
264                                            int *interface_index,
265                                            RoutingTableEntry *entry) {
266  if (message.type() != RTNLMessage::kTypeRoute ||
267      message.family() == IPAddress::kFamilyUnknown ||
268      !message.HasAttribute(RTA_OIF)) {
269    return false;
270  }
271
272  const RTNLMessage::RouteStatus &route_status = message.route_status();
273
274  if (route_status.type != RTN_UNICAST ||
275      route_status.table != RT_TABLE_MAIN) {
276    return false;
277  }
278
279  uint32 interface_index_u32 = 0;
280  if (!message.GetAttribute(RTA_OIF).ConvertToCPUUInt32(&interface_index_u32)) {
281    return false;
282  }
283  *interface_index = interface_index_u32;
284
285  uint32 metric = 0;
286  if (message.HasAttribute(RTA_PRIORITY)) {
287    message.GetAttribute(RTA_PRIORITY).ConvertToCPUUInt32(&metric);
288  }
289
290  IPAddress default_addr(message.family());
291  default_addr.SetAddressToDefault();
292
293  ByteString dst_bytes(default_addr.address());
294  if (message.HasAttribute(RTA_DST)) {
295    dst_bytes = message.GetAttribute(RTA_DST);
296  }
297  ByteString src_bytes(default_addr.address());
298  if (message.HasAttribute(RTA_SRC)) {
299    src_bytes = message.GetAttribute(RTA_SRC);
300  }
301  ByteString gateway_bytes(default_addr.address());
302  if (message.HasAttribute(RTA_GATEWAY)) {
303    gateway_bytes = message.GetAttribute(RTA_GATEWAY);
304  }
305
306  entry->dst = IPAddress(message.family(), dst_bytes, route_status.dst_prefix);
307  entry->src = IPAddress(message.family(), src_bytes, route_status.src_prefix);
308  entry->gateway = IPAddress(message.family(), gateway_bytes);
309  entry->metric = metric;
310  entry->scope = route_status.scope;
311  entry->from_rtnl = true;
312
313  return true;
314}
315
316void RoutingTable::RouteMsgHandler(const RTNLMessage &message) {
317  int interface_index;
318  RoutingTableEntry entry;
319
320  if (!ParseRoutingTableMessage(message, &interface_index, &entry)) {
321    return;
322  }
323
324  if (!route_query_sequences_.empty() &&
325      message.route_status().protocol == RTPROT_UNSPEC) {
326    SLOG(Route, 3) << __func__ << ": Message seq: " << message.seq()
327                   << " mode " << message.mode()
328                   << ", next query seq: " << route_query_sequences_.front();
329
330    // Purge queries that have expired (sequence number of this message is
331    // greater than that of the head of the route query sequence).  Do the
332    // math in a way that's roll-over independent.
333    while (route_query_sequences_.front() - message.seq() > kuint32max / 2) {
334      LOG(ERROR) << __func__ << ": Purging un-replied route request sequence "
335                 << route_query_sequences_.front()
336                 << " (< " << message.seq() << ")";
337      route_query_sequences_.pop();
338      if (route_query_sequences_.empty())
339        return;
340    }
341
342    if (route_query_sequences_.front() == message.seq()) {
343      SLOG(Route, 2) << __func__ << ": Adding host route to "
344                     << entry.dst.ToString();
345      route_query_sequences_.pop();
346      RoutingTableEntry add_entry(entry);
347      add_entry.from_rtnl = false;
348      AddRoute(interface_index, add_entry);
349    }
350    return;
351  } else if (message.route_status().protocol != RTPROT_BOOT) {
352    // Responses to route queries come back with a protocol of
353    // RTPROT_UNSPEC.  Otherwise, normal route updates that we are
354    // interested in come with a protocol of RTPROT_BOOT.
355    return;
356  }
357
358  vector<RoutingTableEntry> &table = tables_[interface_index];
359  vector<RoutingTableEntry>::iterator nent;
360  for (nent = table.begin(); nent != table.end(); ++nent) {
361    if (nent->dst.Equals(entry.dst) &&
362        nent->src.Equals(entry.src) &&
363        nent->gateway.Equals(entry.gateway) &&
364        nent->scope == entry.scope) {
365      if (message.mode() == RTNLMessage::kModeDelete &&
366          nent->metric == entry.metric) {
367        table.erase(nent);
368      } else if (message.mode() == RTNLMessage::kModeAdd) {
369        nent->from_rtnl = true;
370        nent->metric = entry.metric;
371      }
372      return;
373    }
374  }
375
376  if (message.mode() == RTNLMessage::kModeAdd) {
377    SLOG(Route, 2) << __func__ << " adding"
378                   << " destination " << entry.dst.ToString()
379                   << " index " << interface_index
380                   << " gateway " << entry.gateway.ToString()
381                   << " metric " << entry.metric;
382    table.push_back(entry);
383  }
384}
385
386bool RoutingTable::ApplyRoute(uint32 interface_index,
387                              const RoutingTableEntry &entry,
388                              RTNLMessage::Mode mode,
389                              unsigned int flags) {
390  SLOG(Route, 2) << base::StringPrintf(
391      "%s: dst %s/%d src %s/%d index %d mode %d flags 0x%x",
392      __func__, entry.dst.ToString().c_str(), entry.dst.prefix(),
393      entry.src.ToString().c_str(), entry.src.prefix(),
394      interface_index, mode, flags);
395
396  RTNLMessage message(
397      RTNLMessage::kTypeRoute,
398      mode,
399      NLM_F_REQUEST | flags,
400      0,
401      0,
402      0,
403      entry.dst.family());
404
405  message.set_route_status(RTNLMessage::RouteStatus(
406      entry.dst.prefix(),
407      entry.src.prefix(),
408      RT_TABLE_MAIN,
409      RTPROT_BOOT,
410      entry.scope,
411      RTN_UNICAST,
412      0));
413
414  message.SetAttribute(RTA_DST, entry.dst.address());
415  if (!entry.src.IsDefault()) {
416    message.SetAttribute(RTA_SRC, entry.src.address());
417  }
418  if (!entry.gateway.IsDefault()) {
419    message.SetAttribute(RTA_GATEWAY, entry.gateway.address());
420  }
421  message.SetAttribute(RTA_PRIORITY,
422                       ByteString::CreateFromCPUUInt32(entry.metric));
423  message.SetAttribute(RTA_OIF,
424                       ByteString::CreateFromCPUUInt32(interface_index));
425
426  return rtnl_handler_->SendMessage(&message);
427}
428
429// Somewhat surprisingly, the kernel allows you to create multiple routes
430// to the same destination through the same interface with different metrics.
431// Therefore, to change the metric on a route, we can't just use the
432// NLM_F_REPLACE flag by itself.  We have to explicitly remove the old route.
433// We do so after creating the route at a new metric so there is no traffic
434// disruption to existing network streams.
435void RoutingTable::ReplaceMetric(uint32 interface_index,
436                                 RoutingTableEntry *entry,
437                                 uint32 metric) {
438  SLOG(Route, 2) << __func__ << " index " << interface_index
439                 << " metric " << metric;
440  RoutingTableEntry new_entry = *entry;
441  new_entry.metric = metric;
442  // First create the route at the new metric.
443  ApplyRoute(interface_index, new_entry, RTNLMessage::kModeAdd,
444             NLM_F_CREATE | NLM_F_REPLACE);
445  // Then delete the route at the old metric.
446  ApplyRoute(interface_index, *entry, RTNLMessage::kModeDelete, 0);
447  // Now, update our routing table (via |*entry|) from |new_entry|.
448  *entry = new_entry;
449}
450
451bool RoutingTable::FlushCache() {
452  static const char *kPaths[2] = { kRouteFlushPath4, kRouteFlushPath6 };
453  bool ret = true;
454
455  SLOG(Route, 2) << __func__;
456
457  for (size_t i = 0; i < arraysize(kPaths); ++i) {
458    if (file_util::WriteFile(FilePath(kPaths[i]), "-1", 2) != 2) {
459      LOG(ERROR) << base::StringPrintf("Cannot write to route flush file %s",
460                                       kPaths[i]);
461      ret = false;
462    }
463  }
464
465  return ret;
466}
467
468bool RoutingTable::RequestRouteToHost(const IPAddress &address,
469                                      int interface_index) {
470  RTNLMessage message(
471      RTNLMessage::kTypeRoute,
472      RTNLMessage::kModeQuery,
473      NLM_F_REQUEST,
474      0,
475      0,
476      interface_index,
477      address.family());
478
479  RTNLMessage::RouteStatus status;
480  status.dst_prefix = address.prefix();
481  message.set_route_status(status);
482  message.SetAttribute(RTA_DST, address.address());
483
484  if (interface_index != -1) {
485    message.SetAttribute(RTA_OIF,
486                         ByteString::CreateFromCPUUInt32(interface_index));
487  }
488
489  if (!rtnl_handler_->SendMessage(&message)) {
490    return false;
491  }
492
493  // Save the sequence number of the request so we can create a route for
494  // this host when we get a reply.
495  route_query_sequences_.push(message.seq());
496
497  return true;
498}
499
500}  // namespace shill
501