Branch data Line data Source code
1 : : // Copyright (c) 2024-present The Bitcoin Core developers
2 : : // Distributed under the MIT software license, see the accompanying
3 : : // file COPYING or https://www.opensource.org/licenses/mit-license.php.
4 : :
5 : : #include <bitcoin-build-config.h> // IWYU pragma: keep
6 : :
7 : : #include <common/netif.h>
8 : :
9 : : #include <netbase.h>
10 : : #include <util/check.h>
11 : : #include <util/log.h>
12 : : #include <util/sock.h>
13 : :
14 : : #if defined(__linux__)
15 : : #include <linux/rtnetlink.h>
16 : : #elif defined(__FreeBSD__)
17 : : #include <netlink/netlink.h>
18 : : #include <netlink/netlink_route.h>
19 : : #elif defined(WIN32)
20 : : #include <iphlpapi.h>
21 : : #elif defined(__APPLE__)
22 : : #include <net/route.h>
23 : : #include <sys/sysctl.h>
24 : : #endif
25 : :
26 : : #ifdef HAVE_IFADDRS
27 : : #include <ifaddrs.h>
28 : : #endif
29 : :
30 : : #include <type_traits>
31 : :
32 : : namespace {
33 : :
34 : : //! Return CNetAddr for the specified OS-level network address.
35 : : //! If a length is not given, it is taken to be sizeof(struct sockaddr_*) for the family.
36 : 2 : std::optional<CNetAddr> FromSockAddr(const struct sockaddr* addr, std::optional<socklen_t> sa_len_opt)
37 : : {
38 : 2 : socklen_t sa_len = 0;
39 [ - + ]: 2 : if (sa_len_opt.has_value()) {
40 : 0 : sa_len = *sa_len_opt;
41 : : } else {
42 : : // If sockaddr length was not specified, determine it from the family.
43 [ - + + ]: 2 : switch (addr->sa_family) {
44 : : case AF_INET: sa_len = sizeof(struct sockaddr_in); break;
45 : 0 : case AF_INET6: sa_len = sizeof(struct sockaddr_in6); break;
46 : 1 : default:
47 : 1 : return std::nullopt;
48 : : }
49 : : }
50 : : // Fill in a CService from the sockaddr, then drop the port part.
51 : 2 : CService service;
52 [ + - + - ]: 1 : if (service.SetSockAddr(addr, sa_len)) {
53 : 1 : return (CNetAddr)service;
54 : : }
55 : 0 : return std::nullopt;
56 : : }
57 : :
58 : : // Linux and FreeBSD.
59 : : #if defined(__linux__) || defined(__FreeBSD__)
60 : :
61 : : // Good for responses containing ~ 10,000-15,000 routes.
62 : : static constexpr ssize_t NETLINK_MAX_RESPONSE_SIZE{1'048'576};
63 : :
64 : 0 : std::optional<CNetAddr> QueryDefaultGatewayImpl(sa_family_t family)
65 : : {
66 : : // Create a netlink socket.
67 : 0 : auto sock{CreateSock(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE)};
68 [ # # ]: 0 : if (!sock) {
69 [ # # # # ]: 0 : LogError("socket(AF_NETLINK): %s\n", NetworkErrorString(errno));
70 : 0 : return std::nullopt;
71 : : }
72 : :
73 : : // Send request.
74 : 0 : struct {
75 : : nlmsghdr hdr; ///< Request header.
76 : : rtmsg data; ///< Request data, a "route message".
77 : : nlattr dst_hdr; ///< One attribute, conveying the route destination address.
78 : : char dst_data[16]; ///< Route destination address. To query the default route we use 0.0.0.0/0 or [::]/0. For IPv4 the first 4 bytes are used.
79 : 0 : } request{};
80 : :
81 : : // Whether to use the first 4 or 16 bytes from request.dst_data.
82 [ # # ]: 0 : const size_t dst_data_len = family == AF_INET ? 4 : 16;
83 : :
84 : 0 : request.hdr.nlmsg_type = RTM_GETROUTE;
85 : 0 : request.hdr.nlmsg_flags = NLM_F_REQUEST;
86 : : #ifdef __linux__
87 : : // Linux IPv4 / IPv6 - this must be present, otherwise no gateway is found
88 : : // FreeBSD IPv4 - does not matter, the gateway is found with or without this
89 : : // FreeBSD IPv6 - this must be absent, otherwise no gateway is found
90 : 0 : request.hdr.nlmsg_flags |= NLM_F_DUMP;
91 : : #endif
92 : 0 : request.hdr.nlmsg_len = NLMSG_LENGTH(sizeof(rtmsg) + sizeof(nlattr) + dst_data_len);
93 : 0 : request.hdr.nlmsg_seq = 0; // Sequence number, used to match which reply is to which request. Irrelevant for us because we send just one request.
94 : 0 : request.data.rtm_family = family;
95 : 0 : request.data.rtm_dst_len = 0; // Prefix length.
96 : : #ifdef __FreeBSD__
97 : : // Linux IPv4 / IPv6 this must be absent, otherwise no gateway is found
98 : : // FreeBSD IPv4 - does not matter, the gateway is found with or without this
99 : : // FreeBSD IPv6 - this must be present, otherwise no gateway is found
100 : : request.data.rtm_flags = RTM_F_PREFIX;
101 : : #endif
102 : 0 : request.dst_hdr.nla_type = RTA_DST;
103 : 0 : request.dst_hdr.nla_len = sizeof(nlattr) + dst_data_len;
104 : :
105 [ # # # # ]: 0 : if (sock->Send(&request, request.hdr.nlmsg_len, 0) != static_cast<ssize_t>(request.hdr.nlmsg_len)) {
106 [ # # # # ]: 0 : LogError("send() to netlink socket: %s\n", NetworkErrorString(errno));
107 : 0 : return std::nullopt;
108 : : }
109 : :
110 : : // Receive response.
111 : : char response[4096];
112 : : ssize_t total_bytes_read{0};
113 : : bool done{false};
114 [ # # ]: 0 : while (!done) {
115 : 0 : int64_t recv_result;
116 : 0 : do {
117 [ # # ]: 0 : recv_result = sock->Recv(response, sizeof(response), 0);
118 [ # # # # ]: 0 : } while (recv_result < 0 && (errno == EINTR || errno == EAGAIN));
119 [ # # ]: 0 : if (recv_result < 0) {
120 [ # # # # ]: 0 : LogError("recv() from netlink socket: %s\n", NetworkErrorString(errno));
121 : 0 : return std::nullopt;
122 : : }
123 : :
124 : 0 : total_bytes_read += recv_result;
125 [ # # ]: 0 : if (total_bytes_read > NETLINK_MAX_RESPONSE_SIZE) {
126 [ # # ]: 0 : LogWarning("Netlink response exceeded size limit (%zu bytes, family=%d)\n", NETLINK_MAX_RESPONSE_SIZE, family);
127 : 0 : return std::nullopt;
128 : : }
129 : :
130 : : using recv_result_t = std::conditional_t<std::is_signed_v<decltype(NLMSG_HDRLEN)>, int64_t, decltype(NLMSG_HDRLEN)>;
131 : :
132 [ # # # # : 0 : for (nlmsghdr* hdr = (nlmsghdr*)response; NLMSG_OK(hdr, static_cast<recv_result_t>(recv_result)); hdr = NLMSG_NEXT(hdr, recv_result)) {
# # ]
133 [ # # ]: 0 : if (!(hdr->nlmsg_flags & NLM_F_MULTI)) {
134 : 0 : done = true;
135 : : }
136 : :
137 [ # # ]: 0 : if (hdr->nlmsg_type == NLMSG_DONE) {
138 : : done = true;
139 : : break;
140 : : }
141 : :
142 : 0 : rtmsg* r = (rtmsg*)NLMSG_DATA(hdr);
143 : 0 : int remaining_len = RTM_PAYLOAD(hdr);
144 : :
145 [ # # ]: 0 : if (hdr->nlmsg_type != RTM_NEWROUTE) {
146 : 0 : continue; // Skip non-route messages
147 : : }
148 : :
149 : : // Only consider default routes (destination prefix length of 0).
150 [ # # ]: 0 : if (r->rtm_dst_len != 0) {
151 : 0 : continue;
152 : : }
153 : :
154 : : // Iterate over the attributes.
155 : 0 : rtattr* rta_gateway = nullptr;
156 : 0 : int scope_id = 0;
157 [ # # # # : 0 : for (rtattr* attr = RTM_RTA(r); RTA_OK(attr, remaining_len); attr = RTA_NEXT(attr, remaining_len)) {
# # ]
158 [ # # ]: 0 : if (attr->rta_type == RTA_GATEWAY) {
159 : : rta_gateway = attr;
160 [ # # # # ]: 0 : } else if (attr->rta_type == RTA_OIF && sizeof(int) == RTA_PAYLOAD(attr)) {
161 : 0 : std::memcpy(&scope_id, RTA_DATA(attr), sizeof(scope_id));
162 : : }
163 : : }
164 : :
165 : : // Found gateway?
166 [ # # ]: 0 : if (rta_gateway != nullptr) {
167 [ # # # # ]: 0 : if (family == AF_INET && sizeof(in_addr) == RTA_PAYLOAD(rta_gateway)) {
168 : 0 : in_addr gw;
169 [ # # ]: 0 : std::memcpy(&gw, RTA_DATA(rta_gateway), sizeof(gw));
170 [ # # ]: 0 : return CNetAddr(gw);
171 [ # # # # ]: 0 : } else if (family == AF_INET6 && sizeof(in6_addr) == RTA_PAYLOAD(rta_gateway)) {
172 : 0 : in6_addr gw;
173 [ # # ]: 0 : std::memcpy(&gw, RTA_DATA(rta_gateway), sizeof(gw));
174 [ # # ]: 0 : return CNetAddr(gw, scope_id);
175 : : }
176 : : }
177 : : }
178 : : }
179 : :
180 : 0 : return std::nullopt;
181 : 0 : }
182 : :
183 : : #elif defined(WIN32)
184 : :
185 : : std::optional<CNetAddr> QueryDefaultGatewayImpl(sa_family_t family)
186 : : {
187 : : NET_LUID interface_luid = {};
188 : : SOCKADDR_INET destination_address = {};
189 : : MIB_IPFORWARD_ROW2 best_route = {};
190 : : SOCKADDR_INET best_source_address = {};
191 : : DWORD best_if_idx = 0;
192 : : DWORD status = 0;
193 : :
194 : : // Pass empty destination address of the requested type (:: or 0.0.0.0) to get interface of default route.
195 : : destination_address.si_family = family;
196 : : status = GetBestInterfaceEx((sockaddr*)&destination_address, &best_if_idx);
197 : : if (status != NO_ERROR) {
198 : : LogError("Could not get best interface for default route: %s\n", NetworkErrorString(status));
199 : : return std::nullopt;
200 : : }
201 : :
202 : : // Get best route to default gateway.
203 : : // Leave interface_luid at all-zeros to use interface index instead.
204 : : status = GetBestRoute2(&interface_luid, best_if_idx, nullptr, &destination_address, 0, &best_route, &best_source_address);
205 : : if (status != NO_ERROR) {
206 : : LogError("Could not get best route for default route for interface index %d: %s\n",
207 : : best_if_idx, NetworkErrorString(status));
208 : : return std::nullopt;
209 : : }
210 : :
211 : : Assume(best_route.NextHop.si_family == family);
212 : : if (family == AF_INET) {
213 : : return CNetAddr(best_route.NextHop.Ipv4.sin_addr);
214 : : } else if(family == AF_INET6) {
215 : : return CNetAddr(best_route.NextHop.Ipv6.sin6_addr, best_route.InterfaceIndex);
216 : : }
217 : : return std::nullopt;
218 : : }
219 : :
220 : : #elif defined(__APPLE__)
221 : :
222 : : #define ROUNDUP32(a) \
223 : : ((a) > 0 ? (1 + (((a) - 1) | (sizeof(uint32_t) - 1))) : sizeof(uint32_t))
224 : :
225 : : //! MacOS: Get default gateway from route table. See route(4) for the format.
226 : : std::optional<CNetAddr> QueryDefaultGatewayImpl(sa_family_t family)
227 : : {
228 : : // net.route.0.inet[6].flags.gateway
229 : : int mib[] = {CTL_NET, PF_ROUTE, 0, family, NET_RT_FLAGS, RTF_GATEWAY};
230 : : // The size of the available data is determined by calling sysctl() with oldp=nullptr. See sysctl(3).
231 : : size_t l = 0;
232 : : if (sysctl(/*name=*/mib, /*namelen=*/sizeof(mib) / sizeof(int), /*oldp=*/nullptr, /*oldlenp=*/&l, /*newp=*/nullptr, /*newlen=*/0) < 0) {
233 : : LogError("Could not get sysctl length of routing table: %s\n", NetworkErrorString(errno));
234 : : return std::nullopt;
235 : : }
236 : : std::vector<std::byte> buf(l);
237 : : if (sysctl(/*name=*/mib, /*namelen=*/sizeof(mib) / sizeof(int), /*oldp=*/buf.data(), /*oldlenp=*/&l, /*newp=*/nullptr, /*newlen=*/0) < 0) {
238 : : LogError("Could not get sysctl data of routing table: %s\n", NetworkErrorString(errno));
239 : : return std::nullopt;
240 : : }
241 : : // Iterate over messages (each message is a routing table entry).
242 : : for (size_t msg_pos = 0; msg_pos < buf.size(); ) {
243 : : if ((msg_pos + sizeof(rt_msghdr)) > buf.size()) return std::nullopt;
244 : : const struct rt_msghdr* rt = (const struct rt_msghdr*)(buf.data() + msg_pos);
245 : : const size_t next_msg_pos = msg_pos + rt->rtm_msglen;
246 : : if (rt->rtm_msglen < sizeof(rt_msghdr) || next_msg_pos > buf.size()) return std::nullopt;
247 : : // Iterate over addresses within message, get destination and gateway (if present).
248 : : // Address data starts after header.
249 : : size_t sa_pos = msg_pos + sizeof(struct rt_msghdr);
250 : : std::optional<CNetAddr> dst, gateway;
251 : : for (int i = 0; i < RTAX_MAX; i++) {
252 : : if (rt->rtm_addrs & (1 << i)) {
253 : : // 2 is just sa_len + sa_family, the theoretical minimum size of a socket address.
254 : : if ((sa_pos + 2) > next_msg_pos) return std::nullopt;
255 : : const struct sockaddr* sa = (const struct sockaddr*)(buf.data() + sa_pos);
256 : : if ((sa_pos + sa->sa_len) > next_msg_pos) return std::nullopt;
257 : : if (i == RTAX_DST) {
258 : : dst = FromSockAddr(sa, sa->sa_len);
259 : : } else if (i == RTAX_GATEWAY) {
260 : : gateway = FromSockAddr(sa, sa->sa_len);
261 : : }
262 : : // Skip sockaddr entries for bit flags we're not interested in,
263 : : // move cursor.
264 : : sa_pos += ROUNDUP32(sa->sa_len);
265 : : }
266 : : }
267 : : // Found default gateway?
268 : : if (dst && gateway && dst->IsBindAny()) { // Route to 0.0.0.0 or :: ?
269 : : return *gateway;
270 : : }
271 : : // Skip to next message.
272 : : msg_pos = next_msg_pos;
273 : : }
274 : : return std::nullopt;
275 : : }
276 : :
277 : : #else
278 : :
279 : : // Dummy implementation.
280 : : std::optional<CNetAddr> QueryDefaultGatewayImpl(sa_family_t)
281 : : {
282 : : return std::nullopt;
283 : : }
284 : :
285 : : #endif
286 : :
287 : : }
288 : :
289 : 0 : std::optional<CNetAddr> QueryDefaultGateway(Network network)
290 : : {
291 [ # # ]: 0 : Assume(network == NET_IPV4 || network == NET_IPV6);
292 : :
293 : 0 : sa_family_t family;
294 [ # # ]: 0 : if (network == NET_IPV4) {
295 : : family = AF_INET;
296 [ # # ]: 0 : } else if(network == NET_IPV6) {
297 : : family = AF_INET6;
298 : : } else {
299 : 0 : return std::nullopt;
300 : : }
301 : :
302 : 0 : std::optional<CNetAddr> ret = QueryDefaultGatewayImpl(family);
303 : :
304 : : // It's possible for the default gateway to be 0.0.0.0 or ::0 on at least Windows
305 : : // for some routing strategies. If so, return as if no default gateway was found.
306 [ # # # # : 0 : if (ret && !ret->IsBindAny()) {
# # ]
307 [ # # ]: 0 : return ret;
308 : : } else {
309 : 0 : return std::nullopt;
310 : : }
311 : 0 : }
312 : :
313 : 1 : std::vector<CNetAddr> GetLocalAddresses()
314 : : {
315 : 1 : std::vector<CNetAddr> addresses;
316 : : #ifdef WIN32
317 : : DWORD status = 0;
318 : : constexpr size_t MAX_ADAPTER_ADDR_SIZE = 4 * 1000 * 1000; // Absolute maximum size of adapter addresses structure we're willing to handle, as a precaution.
319 : : std::vector<std::byte> out_buf(15000, {}); // Start with 15KB allocation as recommended in GetAdaptersAddresses documentation.
320 : : while (true) {
321 : : ULONG out_buf_len = out_buf.size();
322 : : status = GetAdaptersAddresses(AF_UNSPEC, GAA_FLAG_SKIP_ANYCAST | GAA_FLAG_SKIP_MULTICAST | GAA_FLAG_SKIP_DNS_SERVER | GAA_FLAG_SKIP_FRIENDLY_NAME,
323 : : nullptr, reinterpret_cast<PIP_ADAPTER_ADDRESSES>(out_buf.data()), &out_buf_len);
324 : : if (status == ERROR_BUFFER_OVERFLOW && out_buf.size() < MAX_ADAPTER_ADDR_SIZE) {
325 : : // If status == ERROR_BUFFER_OVERFLOW, out_buf_len will contain the needed size.
326 : : // Unfortunately, this cannot be fully relied on, because another process may have added interfaces.
327 : : // So to avoid getting stuck due to a race condition, double the buffer size at least
328 : : // once before retrying (but only up to the maximum allowed size).
329 : : out_buf.resize(std::min(std::max<size_t>(out_buf_len, out_buf.size()) * 2, MAX_ADAPTER_ADDR_SIZE));
330 : : } else {
331 : : break;
332 : : }
333 : : }
334 : :
335 : : if (status != NO_ERROR) {
336 : : // This includes ERROR_NO_DATA if there are no addresses and thus there's not even one PIP_ADAPTER_ADDRESSES
337 : : // record in the returned structure.
338 : : LogError("Could not get local adapter addresses: %s\n", NetworkErrorString(status));
339 : : return addresses;
340 : : }
341 : :
342 : : // Iterate over network adapters.
343 : : for (PIP_ADAPTER_ADDRESSES cur_adapter = reinterpret_cast<PIP_ADAPTER_ADDRESSES>(out_buf.data());
344 : : cur_adapter != nullptr; cur_adapter = cur_adapter->Next) {
345 : : if (cur_adapter->OperStatus != IfOperStatusUp) continue;
346 : : if (cur_adapter->IfType == IF_TYPE_SOFTWARE_LOOPBACK) continue;
347 : :
348 : : // Iterate over unicast addresses for adapter, the only address type we're interested in.
349 : : for (PIP_ADAPTER_UNICAST_ADDRESS cur_address = cur_adapter->FirstUnicastAddress;
350 : : cur_address != nullptr; cur_address = cur_address->Next) {
351 : : // "The IP address is a cluster address and should not be used by most applications."
352 : : if ((cur_address->Flags & IP_ADAPTER_ADDRESS_TRANSIENT) != 0) continue;
353 : :
354 : : if (std::optional<CNetAddr> addr = FromSockAddr(cur_address->Address.lpSockaddr, static_cast<socklen_t>(cur_address->Address.iSockaddrLength))) {
355 : : addresses.push_back(*addr);
356 : : }
357 : : }
358 : : }
359 : : #elif defined(HAVE_IFADDRS)
360 : 1 : struct ifaddrs* myaddrs;
361 [ + - ]: 1 : if (getifaddrs(&myaddrs) == 0) {
362 [ + + ]: 6 : for (struct ifaddrs* ifa = myaddrs; ifa != nullptr; ifa = ifa->ifa_next)
363 : : {
364 [ - + ]: 5 : if (ifa->ifa_addr == nullptr) continue;
365 [ - + ]: 5 : if ((ifa->ifa_flags & IFF_UP) == 0) continue;
366 [ + + ]: 5 : if ((ifa->ifa_flags & IFF_LOOPBACK) != 0) continue;
367 : :
368 [ + - + + ]: 2 : if (std::optional<CNetAddr> addr = FromSockAddr(ifa->ifa_addr, std::nullopt)) {
369 [ + - ]: 1 : addresses.push_back(*addr);
370 : 2 : }
371 : : }
372 : 1 : freeifaddrs(myaddrs);
373 : : }
374 : : #endif
375 : 1 : return addresses;
376 : 0 : }
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