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1 : : // Copyright (c) 2024 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 <logging.h>
10 : : #include <netbase.h>
11 : : #include <util/check.h>
12 : : #include <util/sock.h>
13 : : #include <util/syserror.h>
14 : :
15 : : #if defined(__linux__)
16 : : #include <linux/rtnetlink.h>
17 : : #elif defined(__FreeBSD__)
18 : : #include <osreldate.h>
19 : : #if __FreeBSD_version >= 1400000
20 : : // Workaround https://github.com/freebsd/freebsd-src/pull/1070.
21 : : #define typeof __typeof
22 : : #include <netlink/netlink.h>
23 : : #include <netlink/netlink_route.h>
24 : : #endif
25 : : #elif defined(WIN32)
26 : : #include <iphlpapi.h>
27 : : #elif defined(__APPLE__)
28 : : #include <net/route.h>
29 : : #include <sys/sysctl.h>
30 : : #endif
31 : :
32 : : #ifdef HAVE_IFADDRS
33 : : #include <sys/types.h>
34 : : #include <ifaddrs.h>
35 : : #endif
36 : :
37 : : namespace {
38 : :
39 : : //! Return CNetAddr for the specified OS-level network address.
40 : : //! If a length is not given, it is taken to be sizeof(struct sockaddr_*) for the family.
41 : 0 : std::optional<CNetAddr> FromSockAddr(const struct sockaddr* addr, std::optional<socklen_t> sa_len_opt)
42 : : {
43 : 0 : socklen_t sa_len = 0;
44 [ # # ]: 0 : if (sa_len_opt.has_value()) {
45 : 0 : sa_len = *sa_len_opt;
46 : : } else {
47 : : // If sockaddr length was not specified, determine it from the family.
48 [ # # # ]: 0 : switch (addr->sa_family) {
49 : : case AF_INET: sa_len = sizeof(struct sockaddr_in); break;
50 : 0 : case AF_INET6: sa_len = sizeof(struct sockaddr_in6); break;
51 : 0 : default:
52 : 0 : return std::nullopt;
53 : : }
54 : : }
55 : : // Fill in a CService from the sockaddr, then drop the port part.
56 : 0 : CService service;
57 [ # # # # ]: 0 : if (service.SetSockAddr(addr, sa_len)) {
58 : 0 : return (CNetAddr)service;
59 : : }
60 : 0 : return std::nullopt;
61 : : }
62 : :
63 : : // Linux and FreeBSD 14.0+. For FreeBSD 13.2 the code can be compiled but
64 : : // running it requires loading a special kernel module, otherwise socket(AF_NETLINK,...)
65 : : // will fail, so we skip that.
66 : : #if defined(__linux__) || (defined(__FreeBSD__) && __FreeBSD_version >= 1400000)
67 : :
68 : 0 : std::optional<CNetAddr> QueryDefaultGatewayImpl(sa_family_t family)
69 : : {
70 : : // Create a netlink socket.
71 : 0 : auto sock{CreateSock(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE)};
72 [ # # ]: 0 : if (!sock) {
73 [ # # # # : 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Error, "socket(AF_NETLINK): %s\n", NetworkErrorString(errno));
# # # # ]
74 : 0 : return std::nullopt;
75 : : }
76 : :
77 : : // Send request.
78 : 0 : struct {
79 : : nlmsghdr hdr; ///< Request header.
80 : : rtmsg data; ///< Request data, a "route message".
81 : : nlattr dst_hdr; ///< One attribute, conveying the route destination address.
82 : : 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.
83 : 0 : } request{};
84 : :
85 : : // Whether to use the first 4 or 16 bytes from request.dst_data.
86 [ # # ]: 0 : const size_t dst_data_len = family == AF_INET ? 4 : 16;
87 : :
88 : 0 : request.hdr.nlmsg_type = RTM_GETROUTE;
89 : 0 : request.hdr.nlmsg_flags = NLM_F_REQUEST;
90 : : #ifdef __linux__
91 : : // Linux IPv4 / IPv6 - this must be present, otherwise no gateway is found
92 : : // FreeBSD IPv4 - does not matter, the gateway is found with or without this
93 : : // FreeBSD IPv6 - this must be absent, otherwise no gateway is found
94 : 0 : request.hdr.nlmsg_flags |= NLM_F_DUMP;
95 : : #endif
96 : 0 : request.hdr.nlmsg_len = NLMSG_LENGTH(sizeof(rtmsg) + sizeof(nlattr) + dst_data_len);
97 : 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.
98 : 0 : request.data.rtm_family = family;
99 : 0 : request.data.rtm_dst_len = 0; // Prefix length.
100 : : #ifdef __FreeBSD__
101 : : // Linux IPv4 / IPv6 this must be absent, otherwise no gateway is found
102 : : // FreeBSD IPv4 - does not matter, the gateway is found with or without this
103 : : // FreeBSD IPv6 - this must be present, otherwise no gateway is found
104 : : request.data.rtm_flags = RTM_F_PREFIX;
105 : : #endif
106 : 0 : request.dst_hdr.nla_type = RTA_DST;
107 : 0 : request.dst_hdr.nla_len = sizeof(nlattr) + dst_data_len;
108 : :
109 [ # # # # ]: 0 : if (sock->Send(&request, request.hdr.nlmsg_len, 0) != static_cast<ssize_t>(request.hdr.nlmsg_len)) {
110 [ # # # # : 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Error, "send() to netlink socket: %s\n", NetworkErrorString(errno));
# # # # ]
111 : 0 : return std::nullopt;
112 : : }
113 : :
114 : : // Receive response.
115 : 0 : char response[4096];
116 : 0 : int64_t recv_result;
117 : 0 : do {
118 [ # # ]: 0 : recv_result = sock->Recv(response, sizeof(response), 0);
119 [ # # # # ]: 0 : } while (recv_result < 0 && (errno == EINTR || errno == EAGAIN));
120 [ # # ]: 0 : if (recv_result < 0) {
121 [ # # # # : 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Error, "recv() from netlink socket: %s\n", NetworkErrorString(errno));
# # # # ]
122 : 0 : return std::nullopt;
123 : : }
124 : :
125 [ # # # # : 0 : for (nlmsghdr* hdr = (nlmsghdr*)response; NLMSG_OK(hdr, recv_result); hdr = NLMSG_NEXT(hdr, recv_result)) {
# # ]
126 : 0 : rtmsg* r = (rtmsg*)NLMSG_DATA(hdr);
127 : 0 : int remaining_len = RTM_PAYLOAD(hdr);
128 : :
129 : : // Iterate over the attributes.
130 : 0 : rtattr *rta_gateway = nullptr;
131 : 0 : int scope_id = 0;
132 [ # # # # : 0 : for (rtattr* attr = RTM_RTA(r); RTA_OK(attr, remaining_len); attr = RTA_NEXT(attr, remaining_len)) {
# # ]
133 [ # # ]: 0 : if (attr->rta_type == RTA_GATEWAY) {
134 : : rta_gateway = attr;
135 [ # # # # ]: 0 : } else if (attr->rta_type == RTA_OIF && sizeof(int) == RTA_PAYLOAD(attr)) {
136 : 0 : std::memcpy(&scope_id, RTA_DATA(attr), sizeof(scope_id));
137 : : }
138 : : }
139 : :
140 : : // Found gateway?
141 [ # # ]: 0 : if (rta_gateway != nullptr) {
142 [ # # # # ]: 0 : if (family == AF_INET && sizeof(in_addr) == RTA_PAYLOAD(rta_gateway)) {
143 : 0 : in_addr gw;
144 [ # # ]: 0 : std::memcpy(&gw, RTA_DATA(rta_gateway), sizeof(gw));
145 [ # # ]: 0 : return CNetAddr(gw);
146 [ # # # # ]: 0 : } else if (family == AF_INET6 && sizeof(in6_addr) == RTA_PAYLOAD(rta_gateway)) {
147 : 0 : in6_addr gw;
148 [ # # ]: 0 : std::memcpy(&gw, RTA_DATA(rta_gateway), sizeof(gw));
149 [ # # ]: 0 : return CNetAddr(gw, scope_id);
150 : : }
151 : : }
152 : : }
153 : :
154 : 0 : return std::nullopt;
155 : 0 : }
156 : :
157 : : #elif defined(WIN32)
158 : :
159 : : std::optional<CNetAddr> QueryDefaultGatewayImpl(sa_family_t family)
160 : : {
161 : : NET_LUID interface_luid = {};
162 : : SOCKADDR_INET destination_address = {};
163 : : MIB_IPFORWARD_ROW2 best_route = {};
164 : : SOCKADDR_INET best_source_address = {};
165 : : DWORD best_if_idx = 0;
166 : : DWORD status = 0;
167 : :
168 : : // Pass empty destination address of the requested type (:: or 0.0.0.0) to get interface of default route.
169 : : destination_address.si_family = family;
170 : : status = GetBestInterfaceEx((sockaddr*)&destination_address, &best_if_idx);
171 : : if (status != NO_ERROR) {
172 : : LogPrintLevel(BCLog::NET, BCLog::Level::Error, "Could not get best interface for default route: %s\n", NetworkErrorString(status));
173 : : return std::nullopt;
174 : : }
175 : :
176 : : // Get best route to default gateway.
177 : : // Leave interface_luid at all-zeros to use interface index instead.
178 : : status = GetBestRoute2(&interface_luid, best_if_idx, nullptr, &destination_address, 0, &best_route, &best_source_address);
179 : : if (status != NO_ERROR) {
180 : : LogPrintLevel(BCLog::NET, BCLog::Level::Error, "Could not get best route for default route for interface index %d: %s\n",
181 : : best_if_idx, NetworkErrorString(status));
182 : : return std::nullopt;
183 : : }
184 : :
185 : : Assume(best_route.NextHop.si_family == family);
186 : : if (family == AF_INET) {
187 : : return CNetAddr(best_route.NextHop.Ipv4.sin_addr);
188 : : } else if(family == AF_INET6) {
189 : : return CNetAddr(best_route.NextHop.Ipv6.sin6_addr, best_route.InterfaceIndex);
190 : : }
191 : : return std::nullopt;
192 : : }
193 : :
194 : : #elif defined(__APPLE__)
195 : :
196 : : #define ROUNDUP32(a) \
197 : : ((a) > 0 ? (1 + (((a) - 1) | (sizeof(uint32_t) - 1))) : sizeof(uint32_t))
198 : :
199 : : //! MacOS: Get default gateway from route table. See route(4) for the format.
200 : : std::optional<CNetAddr> QueryDefaultGatewayImpl(sa_family_t family)
201 : : {
202 : : // net.route.0.inet[6].flags.gateway
203 : : int mib[] = {CTL_NET, PF_ROUTE, 0, family, NET_RT_FLAGS, RTF_GATEWAY};
204 : : // The size of the available data is determined by calling sysctl() with oldp=nullptr. See sysctl(3).
205 : : size_t l = 0;
206 : : if (sysctl(/*name=*/mib, /*namelen=*/sizeof(mib) / sizeof(int), /*oldp=*/nullptr, /*oldlenp=*/&l, /*newp=*/nullptr, /*newlen=*/0) < 0) {
207 : : LogPrintLevel(BCLog::NET, BCLog::Level::Error, "Could not get sysctl length of routing table: %s\n", SysErrorString(errno));
208 : : return std::nullopt;
209 : : }
210 : : std::vector<std::byte> buf(l);
211 : : if (sysctl(/*name=*/mib, /*namelen=*/sizeof(mib) / sizeof(int), /*oldp=*/buf.data(), /*oldlenp=*/&l, /*newp=*/nullptr, /*newlen=*/0) < 0) {
212 : : LogPrintLevel(BCLog::NET, BCLog::Level::Error, "Could not get sysctl data of routing table: %s\n", SysErrorString(errno));
213 : : return std::nullopt;
214 : : }
215 : : // Iterate over messages (each message is a routing table entry).
216 : : for (size_t msg_pos = 0; msg_pos < buf.size(); ) {
217 : : if ((msg_pos + sizeof(rt_msghdr)) > buf.size()) return std::nullopt;
218 : : const struct rt_msghdr* rt = (const struct rt_msghdr*)(buf.data() + msg_pos);
219 : : const size_t next_msg_pos = msg_pos + rt->rtm_msglen;
220 : : if (rt->rtm_msglen < sizeof(rt_msghdr) || next_msg_pos > buf.size()) return std::nullopt;
221 : : // Iterate over addresses within message, get destination and gateway (if present).
222 : : // Address data starts after header.
223 : : size_t sa_pos = msg_pos + sizeof(struct rt_msghdr);
224 : : std::optional<CNetAddr> dst, gateway;
225 : : for (int i = 0; i < RTAX_MAX; i++) {
226 : : if (rt->rtm_addrs & (1 << i)) {
227 : : // 2 is just sa_len + sa_family, the theoretical minimum size of a socket address.
228 : : if ((sa_pos + 2) > next_msg_pos) return std::nullopt;
229 : : const struct sockaddr* sa = (const struct sockaddr*)(buf.data() + sa_pos);
230 : : if ((sa_pos + sa->sa_len) > next_msg_pos) return std::nullopt;
231 : : if (i == RTAX_DST) {
232 : : dst = FromSockAddr(sa, sa->sa_len);
233 : : } else if (i == RTAX_GATEWAY) {
234 : : gateway = FromSockAddr(sa, sa->sa_len);
235 : : }
236 : : // Skip sockaddr entries for bit flags we're not interested in,
237 : : // move cursor.
238 : : sa_pos += ROUNDUP32(sa->sa_len);
239 : : }
240 : : }
241 : : // Found default gateway?
242 : : if (dst && gateway && dst->IsBindAny()) { // Route to 0.0.0.0 or :: ?
243 : : return *gateway;
244 : : }
245 : : // Skip to next message.
246 : : msg_pos = next_msg_pos;
247 : : }
248 : : return std::nullopt;
249 : : }
250 : :
251 : : #else
252 : :
253 : : // Dummy implementation.
254 : : std::optional<CNetAddr> QueryDefaultGatewayImpl(sa_family_t)
255 : : {
256 : : return std::nullopt;
257 : : }
258 : :
259 : : #endif
260 : :
261 : : }
262 : :
263 : 0 : std::optional<CNetAddr> QueryDefaultGateway(Network network)
264 : : {
265 : 0 : Assume(network == NET_IPV4 || network == NET_IPV6);
266 : :
267 : 0 : sa_family_t family;
268 [ # # ]: 0 : if (network == NET_IPV4) {
269 : : family = AF_INET;
270 [ # # ]: 0 : } else if(network == NET_IPV6) {
271 : : family = AF_INET6;
272 : : } else {
273 : 0 : return std::nullopt;
274 : : }
275 : :
276 : 0 : std::optional<CNetAddr> ret = QueryDefaultGatewayImpl(family);
277 : :
278 : : // It's possible for the default gateway to be 0.0.0.0 or ::0 on at least Windows
279 : : // for some routing strategies. If so, return as if no default gateway was found.
280 [ # # # # : 0 : if (ret && !ret->IsBindAny()) {
# # ]
281 [ # # ]: 0 : return ret;
282 : : } else {
283 : 0 : return std::nullopt;
284 : : }
285 : 0 : }
286 : :
287 : 0 : std::vector<CNetAddr> GetLocalAddresses()
288 : : {
289 : 0 : std::vector<CNetAddr> addresses;
290 : : #ifdef WIN32
291 : : DWORD status = 0;
292 : : 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.
293 : : std::vector<std::byte> out_buf(15000, {}); // Start with 15KB allocation as recommended in GetAdaptersAddresses documentation.
294 : : while (true) {
295 : : ULONG out_buf_len = out_buf.size();
296 : : status = GetAdaptersAddresses(AF_UNSPEC, GAA_FLAG_SKIP_ANYCAST | GAA_FLAG_SKIP_MULTICAST | GAA_FLAG_SKIP_DNS_SERVER | GAA_FLAG_SKIP_FRIENDLY_NAME,
297 : : nullptr, reinterpret_cast<PIP_ADAPTER_ADDRESSES>(out_buf.data()), &out_buf_len);
298 : : if (status == ERROR_BUFFER_OVERFLOW && out_buf.size() < MAX_ADAPTER_ADDR_SIZE) {
299 : : // If status == ERROR_BUFFER_OVERFLOW, out_buf_len will contain the needed size.
300 : : // Unfortunately, this cannot be fully relied on, because another process may have added interfaces.
301 : : // So to avoid getting stuck due to a race condition, double the buffer size at least
302 : : // once before retrying (but only up to the maximum allowed size).
303 : : out_buf.resize(std::min(std::max<size_t>(out_buf_len, out_buf.size()) * 2, MAX_ADAPTER_ADDR_SIZE));
304 : : } else {
305 : : break;
306 : : }
307 : : }
308 : :
309 : : if (status != NO_ERROR) {
310 : : // This includes ERROR_NO_DATA if there are no addresses and thus there's not even one PIP_ADAPTER_ADDRESSES
311 : : // record in the returned structure.
312 : : LogPrintLevel(BCLog::NET, BCLog::Level::Error, "Could not get local adapter addresses: %s\n", NetworkErrorString(status));
313 : : return addresses;
314 : : }
315 : :
316 : : // Iterate over network adapters.
317 : : for (PIP_ADAPTER_ADDRESSES cur_adapter = reinterpret_cast<PIP_ADAPTER_ADDRESSES>(out_buf.data());
318 : : cur_adapter != nullptr; cur_adapter = cur_adapter->Next) {
319 : : if (cur_adapter->OperStatus != IfOperStatusUp) continue;
320 : : if (cur_adapter->IfType == IF_TYPE_SOFTWARE_LOOPBACK) continue;
321 : :
322 : : // Iterate over unicast addresses for adapter, the only address type we're interested in.
323 : : for (PIP_ADAPTER_UNICAST_ADDRESS cur_address = cur_adapter->FirstUnicastAddress;
324 : : cur_address != nullptr; cur_address = cur_address->Next) {
325 : : // "The IP address is a cluster address and should not be used by most applications."
326 : : if ((cur_address->Flags & IP_ADAPTER_ADDRESS_TRANSIENT) != 0) continue;
327 : :
328 : : if (std::optional<CNetAddr> addr = FromSockAddr(cur_address->Address.lpSockaddr, static_cast<socklen_t>(cur_address->Address.iSockaddrLength))) {
329 : : addresses.push_back(*addr);
330 : : }
331 : : }
332 : : }
333 : : #elif defined(HAVE_IFADDRS)
334 : 0 : struct ifaddrs* myaddrs;
335 [ # # ]: 0 : if (getifaddrs(&myaddrs) == 0) {
336 [ # # ]: 0 : for (struct ifaddrs* ifa = myaddrs; ifa != nullptr; ifa = ifa->ifa_next)
337 : : {
338 [ # # ]: 0 : if (ifa->ifa_addr == nullptr) continue;
339 [ # # ]: 0 : if ((ifa->ifa_flags & IFF_UP) == 0) continue;
340 [ # # ]: 0 : if ((ifa->ifa_flags & IFF_LOOPBACK) != 0) continue;
341 : :
342 [ # # # # ]: 0 : if (std::optional<CNetAddr> addr = FromSockAddr(ifa->ifa_addr, std::nullopt)) {
343 [ # # ]: 0 : addresses.push_back(*addr);
344 : 0 : }
345 : : }
346 : 0 : freeifaddrs(myaddrs);
347 : : }
348 : : #endif
349 : 0 : return addresses;
350 : 0 : }
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