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