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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 <common/pcp.h>
6 : :
7 : : #include <common/netif.h>
8 : : #include <crypto/common.h>
9 : : #include <logging.h>
10 : : #include <netaddress.h>
11 : : #include <netbase.h>
12 : : #include <random.h>
13 : : #include <span.h>
14 : : #include <util/check.h>
15 : : #include <util/readwritefile.h>
16 : : #include <util/sock.h>
17 : : #include <util/strencodings.h>
18 : :
19 : : namespace {
20 : :
21 : : // RFC6886 NAT-PMP and RFC6887 Port Control Protocol (PCP) implementation.
22 : : // NAT-PMP and PCP use network byte order (big-endian).
23 : :
24 : : // NAT-PMP (v0) protocol constants.
25 : : //! NAT-PMP uses a fixed server port number (RFC6887 section 1.1).
26 : : constexpr uint16_t NATPMP_SERVER_PORT = 5351;
27 : : //! Version byte for NATPMP (RFC6886 1.1)
28 : : constexpr uint8_t NATPMP_VERSION = 0;
29 : : //! Request opcode base (RFC6886 3).
30 : : constexpr uint8_t NATPMP_REQUEST = 0x00;
31 : : //! Response opcode base (RFC6886 3).
32 : : constexpr uint8_t NATPMP_RESPONSE = 0x80;
33 : : //! Get external address (RFC6886 3.2)
34 : : constexpr uint8_t NATPMP_OP_GETEXTERNAL = 0x00;
35 : : //! Map TCP port (RFC6886 3.3)
36 : : constexpr uint8_t NATPMP_OP_MAP_TCP = 0x02;
37 : : //! Shared request header size in bytes.
38 : : constexpr size_t NATPMP_REQUEST_HDR_SIZE = 2;
39 : : //! Shared response header (minimum) size in bytes.
40 : : constexpr size_t NATPMP_RESPONSE_HDR_SIZE = 8;
41 : : //! GETEXTERNAL request size in bytes, including header (RFC6886 3.2).
42 : : constexpr size_t NATPMP_GETEXTERNAL_REQUEST_SIZE = NATPMP_REQUEST_HDR_SIZE + 0;
43 : : //! GETEXTERNAL response size in bytes, including header (RFC6886 3.2).
44 : : constexpr size_t NATPMP_GETEXTERNAL_RESPONSE_SIZE = NATPMP_RESPONSE_HDR_SIZE + 4;
45 : : //! MAP request size in bytes, including header (RFC6886 3.3).
46 : : constexpr size_t NATPMP_MAP_REQUEST_SIZE = NATPMP_REQUEST_HDR_SIZE + 10;
47 : : //! MAP response size in bytes, including header (RFC6886 3.3).
48 : : constexpr size_t NATPMP_MAP_RESPONSE_SIZE = NATPMP_RESPONSE_HDR_SIZE + 8;
49 : :
50 : : // Shared header offsets (RFC6886 3.2, 3.3), relative to start of packet.
51 : : //! Offset of version field in packets.
52 : : constexpr size_t NATPMP_HDR_VERSION_OFS = 0;
53 : : //! Offset of opcode field in packets
54 : : constexpr size_t NATPMP_HDR_OP_OFS = 1;
55 : : //! Offset of result code in packets. Result codes are 16 bit in NAT-PMP instead of 8 bit in PCP.
56 : : constexpr size_t NATPMP_RESPONSE_HDR_RESULT_OFS = 2;
57 : :
58 : : // GETEXTERNAL response offsets (RFC6886 3.2), relative to start of packet.
59 : : //! Returned external address
60 : : constexpr size_t NATPMP_GETEXTERNAL_RESPONSE_IP_OFS = 8;
61 : :
62 : : // MAP request offsets (RFC6886 3.3), relative to start of packet.
63 : : //! Internal port to be mapped.
64 : : constexpr size_t NATPMP_MAP_REQUEST_INTERNAL_PORT_OFS = 4;
65 : : //! Suggested external port for mapping.
66 : : constexpr size_t NATPMP_MAP_REQUEST_EXTERNAL_PORT_OFS = 6;
67 : : //! Requested port mapping lifetime in seconds.
68 : : constexpr size_t NATPMP_MAP_REQUEST_LIFETIME_OFS = 8;
69 : :
70 : : // MAP response offsets (RFC6886 3.3), relative to start of packet.
71 : : //! Internal port for mapping (will match internal port of request).
72 : : constexpr size_t NATPMP_MAP_RESPONSE_INTERNAL_PORT_OFS = 8;
73 : : //! External port for mapping.
74 : : constexpr size_t NATPMP_MAP_RESPONSE_EXTERNAL_PORT_OFS = 10;
75 : : //! Created port mapping lifetime in seconds.
76 : : constexpr size_t NATPMP_MAP_RESPONSE_LIFETIME_OFS = 12;
77 : :
78 : : // Relevant NETPMP result codes (RFC6886 3.5).
79 : : //! Result code representing success status.
80 : : constexpr uint8_t NATPMP_RESULT_SUCCESS = 0;
81 : : //! Result code representing unsupported version.
82 : : constexpr uint8_t NATPMP_RESULT_UNSUPP_VERSION = 1;
83 : : //! Result code representing lack of resources.
84 : : constexpr uint8_t NATPMP_RESULT_NO_RESOURCES = 4;
85 : :
86 : : //! Mapping of NATPMP result code to string (RFC6886 3.5). Result codes <=2 match PCP.
87 : : const std::map<uint8_t, std::string> NATPMP_RESULT_STR{
88 : : {0, "SUCCESS"},
89 : : {1, "UNSUPP_VERSION"},
90 : : {2, "NOT_AUTHORIZED"},
91 : : {3, "NETWORK_FAILURE"},
92 : : {4, "NO_RESOURCES"},
93 : : {5, "UNSUPP_OPCODE"},
94 : : };
95 : :
96 : : // PCP (v2) protocol constants.
97 : : //! Maximum packet size in bytes (RFC6887 section 7).
98 : : constexpr size_t PCP_MAX_SIZE = 1100;
99 : : //! PCP uses a fixed server port number (RFC6887 section 19.1). Shared with NAT-PMP.
100 : : constexpr uint16_t PCP_SERVER_PORT = NATPMP_SERVER_PORT;
101 : : //! Version byte. 0 is NAT-PMP (RFC6886), 1 is forbidden, 2 for PCP (RFC6887).
102 : : constexpr uint8_t PCP_VERSION = 2;
103 : : //! PCP Request Header. See RFC6887 section 7.1. Shared with NAT-PMP.
104 : : constexpr uint8_t PCP_REQUEST = NATPMP_REQUEST; // R = 0
105 : : //! PCP Response Header. See RFC6887 section 7.2. Shared with NAT-PMP.
106 : : constexpr uint8_t PCP_RESPONSE = NATPMP_RESPONSE; // R = 1
107 : : //! Map opcode. See RFC6887 section 19.2
108 : : constexpr uint8_t PCP_OP_MAP = 0x01;
109 : : //! TCP protocol number (IANA).
110 : : constexpr uint16_t PCP_PROTOCOL_TCP = 6;
111 : : //! Request and response header size in bytes (RFC6887 section 7.1).
112 : : constexpr size_t PCP_HDR_SIZE = 24;
113 : : //! Map request and response size in bytes (RFC6887 section 11.1).
114 : : constexpr size_t PCP_MAP_SIZE = 36;
115 : :
116 : : // Header offsets shared between request and responses (RFC6887 7.1, 7.2), relative to start of packet.
117 : : //! Version field (1 byte).
118 : : constexpr size_t PCP_HDR_VERSION_OFS = NATPMP_HDR_VERSION_OFS;
119 : : //! Opcode field (1 byte).
120 : : constexpr size_t PCP_HDR_OP_OFS = NATPMP_HDR_OP_OFS;
121 : : //! Requested lifetime (request), granted lifetime (response) (4 bytes).
122 : : constexpr size_t PCP_HDR_LIFETIME_OFS = 4;
123 : :
124 : : // Request header offsets (RFC6887 7.1), relative to start of packet.
125 : : //! PCP client's IP address (16 bytes).
126 : : constexpr size_t PCP_REQUEST_HDR_IP_OFS = 8;
127 : :
128 : : // Response header offsets (RFC6887 7.2), relative to start of packet.
129 : : //! Result code (1 byte).
130 : : constexpr size_t PCP_RESPONSE_HDR_RESULT_OFS = 3;
131 : :
132 : : // MAP request/response offsets (RFC6887 11.1), relative to start of opcode-specific data.
133 : : //! Mapping nonce (12 bytes).
134 : : constexpr size_t PCP_MAP_NONCE_OFS = 0;
135 : : //! Protocol (1 byte).
136 : : constexpr size_t PCP_MAP_PROTOCOL_OFS = 12;
137 : : //! Internal port for mapping (2 bytes).
138 : : constexpr size_t PCP_MAP_INTERNAL_PORT_OFS = 16;
139 : : //! Suggested external port (request), assigned external port (response) (2 bytes).
140 : : constexpr size_t PCP_MAP_EXTERNAL_PORT_OFS = 18;
141 : : //! Suggested external IP (request), assigned external IP (response) (16 bytes).
142 : : constexpr size_t PCP_MAP_EXTERNAL_IP_OFS = 20;
143 : :
144 : : //! Result code representing success (RFC6887 7.4), shared with NAT-PMP.
145 : : constexpr uint8_t PCP_RESULT_SUCCESS = NATPMP_RESULT_SUCCESS;
146 : : //! Result code representing lack of resources (RFC6887 7.4).
147 : : constexpr uint8_t PCP_RESULT_NO_RESOURCES = 8;
148 : :
149 : : //! Mapping of PCP result code to string (RFC6887 7.4). Result codes <=2 match NAT-PMP.
150 : : const std::map<uint8_t, std::string> PCP_RESULT_STR{
151 : : {0, "SUCCESS"},
152 : : {1, "UNSUPP_VERSION"},
153 : : {2, "NOT_AUTHORIZED"},
154 : : {3, "MALFORMED_REQUEST"},
155 : : {4, "UNSUPP_OPCODE"},
156 : : {5, "UNSUPP_OPTION"},
157 : : {6, "MALFORMED_OPTION"},
158 : : {7, "NETWORK_FAILURE"},
159 : : {8, "NO_RESOURCES"},
160 : : {9, "UNSUPP_PROTOCOL"},
161 : : {10, "USER_EX_QUOTA"},
162 : : {11, "CANNOT_PROVIDE_EXTERNAL"},
163 : : {12, "ADDRESS_MISMATCH"},
164 : : {13, "EXCESSIVE_REMOTE_PEER"},
165 : : };
166 : :
167 : : //! Return human-readable string from NATPMP result code.
168 : 0 : std::string NATPMPResultString(uint8_t result_code)
169 : : {
170 : 0 : auto result_i = NATPMP_RESULT_STR.find(result_code);
171 [ # # # # ]: 0 : return strprintf("%s (code %d)", result_i == NATPMP_RESULT_STR.end() ? "(unknown)" : result_i->second, result_code);
172 : : }
173 : :
174 : : //! Return human-readable string from PCP result code.
175 : 0 : std::string PCPResultString(uint8_t result_code)
176 : : {
177 : 0 : auto result_i = PCP_RESULT_STR.find(result_code);
178 [ # # # # ]: 0 : return strprintf("%s (code %d)", result_i == PCP_RESULT_STR.end() ? "(unknown)" : result_i->second, result_code);
179 : : }
180 : :
181 : : //! Wrap address in IPv6 according to RFC6887. wrapped_addr needs to be able to store 16 bytes.
182 : 0 : [[nodiscard]] bool PCPWrapAddress(Span<uint8_t> wrapped_addr, const CNetAddr &addr)
183 : : {
184 : 0 : Assume(wrapped_addr.size() == ADDR_IPV6_SIZE);
185 [ # # ]: 0 : if (addr.IsIPv4()) {
186 : 0 : struct in_addr addr4;
187 [ # # ]: 0 : if (!addr.GetInAddr(&addr4)) return false;
188 : : // Section 5: "When the address field holds an IPv4 address, an IPv4-mapped IPv6 address [RFC4291] is used (::ffff:0:0/96)."
189 : 0 : std::memcpy(wrapped_addr.data(), IPV4_IN_IPV6_PREFIX.data(), IPV4_IN_IPV6_PREFIX.size());
190 : 0 : std::memcpy(wrapped_addr.data() + IPV4_IN_IPV6_PREFIX.size(), &addr4, ADDR_IPV4_SIZE);
191 : 0 : return true;
192 [ # # ]: 0 : } else if (addr.IsIPv6()) {
193 : 0 : struct in6_addr addr6;
194 [ # # ]: 0 : if (!addr.GetIn6Addr(&addr6)) return false;
195 : 0 : std::memcpy(wrapped_addr.data(), &addr6, ADDR_IPV6_SIZE);
196 : 0 : return true;
197 : : } else {
198 : : return false;
199 : : }
200 : : }
201 : :
202 : : //! Unwrap PCP-encoded address according to RFC6887.
203 : 0 : CNetAddr PCPUnwrapAddress(Span<const uint8_t> wrapped_addr)
204 : : {
205 : 0 : Assume(wrapped_addr.size() == ADDR_IPV6_SIZE);
206 [ # # ]: 0 : if (util::HasPrefix(wrapped_addr, IPV4_IN_IPV6_PREFIX)) {
207 : 0 : struct in_addr addr4;
208 : 0 : std::memcpy(&addr4, wrapped_addr.data() + IPV4_IN_IPV6_PREFIX.size(), ADDR_IPV4_SIZE);
209 : 0 : return CNetAddr(addr4);
210 : : } else {
211 : 0 : struct in6_addr addr6;
212 : 0 : std::memcpy(&addr6, wrapped_addr.data(), ADDR_IPV6_SIZE);
213 : 0 : return CNetAddr(addr6);
214 : : }
215 : : }
216 : :
217 : : //! PCP or NAT-PMP send-receive loop.
218 : 0 : std::optional<std::vector<uint8_t>> PCPSendRecv(Sock &sock, const std::string &protocol, Span<const uint8_t> request, int num_tries,
219 : : std::chrono::milliseconds timeout_per_try,
220 : : std::function<bool(Span<const uint8_t>)> check_packet)
221 : : {
222 : 0 : using namespace std::chrono;
223 : : // UDP is a potentially lossy protocol, so we try to send again a few times.
224 : 0 : uint8_t response[PCP_MAX_SIZE];
225 : 0 : bool got_response = false;
226 : 0 : int recvsz = 0;
227 [ # # # # ]: 0 : for (int ntry = 0; !got_response && ntry < num_tries; ++ntry) {
228 [ # # ]: 0 : if (ntry > 0) {
229 [ # # ]: 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Debug, "%s: Retrying (%d)\n", protocol, ntry);
230 : : }
231 : : // Dispatch packet to gateway.
232 [ # # ]: 0 : if (sock.Send(request.data(), request.size(), 0) != static_cast<ssize_t>(request.size())) {
233 [ # # # # ]: 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "%s: Could not send request: %s\n", protocol, NetworkErrorString(WSAGetLastError()));
234 : 0 : return std::nullopt; // Network-level error, probably no use retrying.
235 : : }
236 : :
237 : : // Wait for response(s) until we get a valid response, a network error, or time out.
238 : 0 : auto cur_time = time_point_cast<milliseconds>(steady_clock::now());
239 : 0 : auto deadline = cur_time + timeout_per_try;
240 [ # # ]: 0 : while ((cur_time = time_point_cast<milliseconds>(steady_clock::now())) < deadline) {
241 : 0 : Sock::Event occurred = 0;
242 [ # # ]: 0 : if (!sock.Wait(deadline - cur_time, Sock::RECV, &occurred)) {
243 [ # # # # ]: 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "%s: Could not wait on socket: %s\n", protocol, NetworkErrorString(WSAGetLastError()));
244 : 0 : return std::nullopt; // Network-level error, probably no use retrying.
245 : : }
246 [ # # ]: 0 : if (!occurred) {
247 [ # # ]: 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Debug, "%s: Timeout\n", protocol);
248 : : break; // Retry.
249 : : }
250 : :
251 : : // Receive response.
252 : 0 : recvsz = sock.Recv(response, sizeof(response), MSG_DONTWAIT);
253 [ # # ]: 0 : if (recvsz < 0) {
254 [ # # # # ]: 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "%s: Could not receive response: %s\n", protocol, NetworkErrorString(WSAGetLastError()));
255 : 0 : return std::nullopt; // Network-level error, probably no use retrying.
256 : : }
257 [ # # # # ]: 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Debug, "%s: Received response of %d bytes: %s\n", protocol, recvsz, HexStr(Span(response, recvsz)));
258 : :
259 [ # # ]: 0 : if (check_packet(Span<uint8_t>(response, recvsz))) {
260 : : got_response = true; // Got expected response, break from receive loop as well as from retry loop.
261 : : break;
262 : : }
263 : : }
264 : : }
265 [ # # ]: 0 : if (!got_response) {
266 [ # # ]: 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Debug, "%s: Giving up after %d tries\n", protocol, num_tries);
267 : 0 : return std::nullopt;
268 : : }
269 : 0 : return std::vector<uint8_t>(response, response + recvsz);
270 : : }
271 : :
272 : : }
273 : :
274 : 0 : std::variant<MappingResult, MappingError> NATPMPRequestPortMap(const CNetAddr &gateway, uint16_t port, uint32_t lifetime, int num_tries, std::chrono::milliseconds timeout_per_try)
275 : : {
276 : 0 : struct sockaddr_storage dest_addr;
277 : 0 : socklen_t dest_addrlen = sizeof(struct sockaddr_storage);
278 : :
279 [ # # # # ]: 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Debug, "natpmp: Requesting port mapping port %d from gateway %s\n", port, gateway.ToStringAddr());
280 : :
281 : : // Validate gateway, make sure it's IPv4. NAT-PMP does not support IPv6.
282 [ # # # # ]: 0 : if (!CService(gateway, PCP_SERVER_PORT).GetSockAddr((struct sockaddr*)&dest_addr, &dest_addrlen)) return MappingError::NETWORK_ERROR;
283 [ # # ]: 0 : if (dest_addr.ss_family != AF_INET) return MappingError::NETWORK_ERROR;
284 : :
285 : : // Create IPv4 UDP socket
286 : 0 : auto sock{CreateSock(AF_INET, SOCK_DGRAM, IPPROTO_UDP)};
287 [ # # ]: 0 : if (!sock) {
288 [ # # # # : 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "natpmp: Could not create UDP socket: %s\n", NetworkErrorString(WSAGetLastError()));
# # # # ]
289 : 0 : return MappingError::NETWORK_ERROR;
290 : : }
291 : :
292 : : // Associate UDP socket to gateway.
293 [ # # # # ]: 0 : if (sock->Connect((struct sockaddr*)&dest_addr, dest_addrlen) != 0) {
294 [ # # # # : 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "natpmp: Could not connect to gateway: %s\n", NetworkErrorString(WSAGetLastError()));
# # # # ]
295 : 0 : return MappingError::NETWORK_ERROR;
296 : : }
297 : :
298 : : // Use getsockname to get the address toward the default gateway (the internal address).
299 : 0 : struct sockaddr_in internal;
300 : 0 : socklen_t internal_addrlen = sizeof(struct sockaddr_in);
301 [ # # # # ]: 0 : if (sock->GetSockName((struct sockaddr*)&internal, &internal_addrlen) != 0) {
302 [ # # # # : 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "natpmp: Could not get sock name: %s\n", NetworkErrorString(WSAGetLastError()));
# # # # ]
303 : 0 : return MappingError::NETWORK_ERROR;
304 : : }
305 : :
306 : : // Request external IP address (RFC6886 section 3.2).
307 [ # # ]: 0 : std::vector<uint8_t> request(NATPMP_GETEXTERNAL_REQUEST_SIZE);
308 [ # # ]: 0 : request[NATPMP_HDR_VERSION_OFS] = NATPMP_VERSION;
309 : 0 : request[NATPMP_HDR_OP_OFS] = NATPMP_REQUEST | NATPMP_OP_GETEXTERNAL;
310 : :
311 [ # # ]: 0 : auto recv_res = PCPSendRecv(*sock, "natpmp", request, num_tries, timeout_per_try,
312 : 0 : [&](const Span<const uint8_t> response) -> bool {
313 [ # # ]: 0 : if (response.size() < NATPMP_GETEXTERNAL_RESPONSE_SIZE) {
314 [ # # ]: 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "natpmp: Response too small\n");
315 : 0 : return false; // Wasn't response to what we expected, try receiving next packet.
316 : : }
317 [ # # # # ]: 0 : if (response[NATPMP_HDR_VERSION_OFS] != NATPMP_VERSION || response[NATPMP_HDR_OP_OFS] != (NATPMP_RESPONSE | NATPMP_OP_GETEXTERNAL)) {
318 [ # # ]: 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "natpmp: Response to wrong command\n");
319 : 0 : return false; // Wasn't response to what we expected, try receiving next packet.
320 : : }
321 : : return true;
322 [ # # ]: 0 : });
323 : :
324 : 0 : struct in_addr external_addr;
325 [ # # ]: 0 : if (recv_res) {
326 [ # # ]: 0 : const std::span<const uint8_t> response = *recv_res;
327 : :
328 [ # # ]: 0 : Assume(response.size() >= NATPMP_GETEXTERNAL_RESPONSE_SIZE);
329 [ # # ]: 0 : uint16_t result_code = ReadBE16(response.data() + NATPMP_RESPONSE_HDR_RESULT_OFS);
330 [ # # ]: 0 : if (result_code != NATPMP_RESULT_SUCCESS) {
331 [ # # # # : 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "natpmp: Getting external address failed with result %s\n", NATPMPResultString(result_code));
# # # # ]
332 : 0 : return MappingError::PROTOCOL_ERROR;
333 : : }
334 : :
335 [ # # ]: 0 : std::memcpy(&external_addr, response.data() + NATPMP_GETEXTERNAL_RESPONSE_IP_OFS, ADDR_IPV4_SIZE);
336 : : } else {
337 : 0 : return MappingError::NETWORK_ERROR;
338 : : }
339 : :
340 : : // Create TCP mapping request (RFC6886 section 3.3).
341 [ # # ]: 0 : request = std::vector<uint8_t>(NATPMP_MAP_REQUEST_SIZE);
342 : 0 : request[NATPMP_HDR_VERSION_OFS] = NATPMP_VERSION;
343 : 0 : request[NATPMP_HDR_OP_OFS] = NATPMP_REQUEST | NATPMP_OP_MAP_TCP;
344 : 0 : WriteBE16(request.data() + NATPMP_MAP_REQUEST_INTERNAL_PORT_OFS, port);
345 : 0 : WriteBE16(request.data() + NATPMP_MAP_REQUEST_EXTERNAL_PORT_OFS, port);
346 : 0 : WriteBE32(request.data() + NATPMP_MAP_REQUEST_LIFETIME_OFS, lifetime);
347 : :
348 [ # # ]: 0 : recv_res = PCPSendRecv(*sock, "natpmp", request, num_tries, timeout_per_try,
349 [ # # ]: 0 : [&](const Span<const uint8_t> response) -> bool {
350 [ # # ]: 0 : if (response.size() < NATPMP_MAP_RESPONSE_SIZE) {
351 [ # # ]: 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "natpmp: Response too small\n");
352 : 0 : return false; // Wasn't response to what we expected, try receiving next packet.
353 : : }
354 [ # # # # ]: 0 : if (response[0] != NATPMP_VERSION || response[1] != (NATPMP_RESPONSE | NATPMP_OP_MAP_TCP)) {
355 [ # # ]: 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "natpmp: Response to wrong command\n");
356 : 0 : return false; // Wasn't response to what we expected, try receiving next packet.
357 : : }
358 [ # # ]: 0 : uint16_t internal_port = ReadBE16(response.data() + NATPMP_MAP_RESPONSE_INTERNAL_PORT_OFS);
359 [ # # ]: 0 : if (internal_port != port) {
360 [ # # ]: 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "natpmp: Response port doesn't match request\n");
361 : 0 : return false; // Wasn't response to what we expected, try receiving next packet.
362 : : }
363 : : return true;
364 : 0 : });
365 : :
366 [ # # ]: 0 : if (recv_res) {
367 [ # # ]: 0 : const std::span<uint8_t> response = *recv_res;
368 : :
369 [ # # ]: 0 : Assume(response.size() >= NATPMP_MAP_RESPONSE_SIZE);
370 [ # # ]: 0 : uint16_t result_code = ReadBE16(response.data() + NATPMP_RESPONSE_HDR_RESULT_OFS);
371 [ # # ]: 0 : if (result_code != NATPMP_RESULT_SUCCESS) {
372 [ # # # # : 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "natpmp: Port mapping failed with result %s\n", NATPMPResultString(result_code));
# # # # ]
373 [ # # ]: 0 : if (result_code == NATPMP_RESULT_NO_RESOURCES) {
374 : 0 : return MappingError::NO_RESOURCES;
375 : : }
376 : 0 : return MappingError::PROTOCOL_ERROR;
377 : : }
378 : :
379 [ # # ]: 0 : uint32_t lifetime_ret = ReadBE32(response.data() + NATPMP_MAP_RESPONSE_LIFETIME_OFS);
380 [ # # ]: 0 : uint16_t external_port = ReadBE16(response.data() + NATPMP_MAP_RESPONSE_EXTERNAL_PORT_OFS);
381 [ # # # # ]: 0 : return MappingResult(NATPMP_VERSION, CService(internal.sin_addr, port), CService(external_addr, external_port), lifetime_ret);
382 : : } else {
383 : 0 : return MappingError::NETWORK_ERROR;
384 : : }
385 : 0 : }
386 : :
387 : 0 : std::variant<MappingResult, MappingError> PCPRequestPortMap(const PCPMappingNonce &nonce, const CNetAddr &gateway, const CNetAddr &bind, uint16_t port, uint32_t lifetime, int num_tries, std::chrono::milliseconds timeout_per_try)
388 : : {
389 : 0 : struct sockaddr_storage dest_addr, bind_addr;
390 : 0 : socklen_t dest_addrlen = sizeof(struct sockaddr_storage), bind_addrlen = sizeof(struct sockaddr_storage);
391 : :
392 [ # # # # : 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Debug, "pcp: Requesting port mapping for addr %s port %d from gateway %s\n", bind.ToStringAddr(), port, gateway.ToStringAddr());
# # ]
393 : :
394 : : // Validate addresses, make sure they're the same network family.
395 [ # # # # ]: 0 : if (!CService(gateway, PCP_SERVER_PORT).GetSockAddr((struct sockaddr*)&dest_addr, &dest_addrlen)) return MappingError::NETWORK_ERROR;
396 [ # # # # ]: 0 : if (!CService(bind, 0).GetSockAddr((struct sockaddr*)&bind_addr, &bind_addrlen)) return MappingError::NETWORK_ERROR;
397 [ # # ]: 0 : if (dest_addr.ss_family != bind_addr.ss_family) return MappingError::NETWORK_ERROR;
398 : :
399 : : // Create UDP socket (IPv4 or IPv6 based on provided gateway).
400 : 0 : auto sock{CreateSock(dest_addr.ss_family, SOCK_DGRAM, IPPROTO_UDP)};
401 [ # # ]: 0 : if (!sock) {
402 [ # # # # : 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "pcp: Could not create UDP socket: %s\n", NetworkErrorString(WSAGetLastError()));
# # # # ]
403 : 0 : return MappingError::NETWORK_ERROR;
404 : : }
405 : :
406 : : // Make sure that we send from requested destination address, anything else will be
407 : : // rejected by a security-conscious router.
408 [ # # # # ]: 0 : if (sock->Bind((struct sockaddr*)&bind_addr, bind_addrlen) != 0) {
409 [ # # # # : 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "pcp: Could not bind to address: %s\n", NetworkErrorString(WSAGetLastError()));
# # # # ]
410 : 0 : return MappingError::NETWORK_ERROR;
411 : : }
412 : :
413 : : // Associate UDP socket to gateway.
414 [ # # # # ]: 0 : if (sock->Connect((struct sockaddr*)&dest_addr, dest_addrlen) != 0) {
415 [ # # # # : 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "pcp: Could not connect to gateway: %s\n", NetworkErrorString(WSAGetLastError()));
# # # # ]
416 : 0 : return MappingError::NETWORK_ERROR;
417 : : }
418 : :
419 : : // Use getsockname to get the address toward the default gateway (the internal address),
420 : : // in case we don't know what address to map
421 : : // (this is only needed if bind is INADDR_ANY, but it doesn't hurt as an extra check).
422 : 0 : struct sockaddr_storage internal_addr;
423 : 0 : socklen_t internal_addrlen = sizeof(struct sockaddr_storage);
424 [ # # # # ]: 0 : if (sock->GetSockName((struct sockaddr*)&internal_addr, &internal_addrlen) != 0) {
425 [ # # # # : 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "pcp: Could not get sock name: %s\n", NetworkErrorString(WSAGetLastError()));
# # # # ]
426 : 0 : return MappingError::NETWORK_ERROR;
427 : : }
428 [ # # ]: 0 : CService internal;
429 [ # # # # ]: 0 : if (!internal.SetSockAddr((struct sockaddr*)&internal_addr)) return MappingError::NETWORK_ERROR;
430 [ # # # # : 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Debug, "pcp: Internal address after connect: %s\n", internal.ToStringAddr());
# # # # ]
431 : :
432 : : // Build request packet. Make sure the packet is zeroed so that reserved fields are zero
433 : : // as required by the spec (and not potentially leak data).
434 : : // Make sure there's space for the request header and MAP specific request data.
435 [ # # ]: 0 : std::vector<uint8_t> request(PCP_HDR_SIZE + PCP_MAP_SIZE);
436 : : // Fill in request header, See RFC6887 Figure 2.
437 : 0 : size_t ofs = 0;
438 : 0 : request[ofs + PCP_HDR_VERSION_OFS] = PCP_VERSION;
439 : 0 : request[ofs + PCP_HDR_OP_OFS] = PCP_REQUEST | PCP_OP_MAP;
440 : 0 : WriteBE32(request.data() + ofs + PCP_HDR_LIFETIME_OFS, lifetime);
441 [ # # # # ]: 0 : if (!PCPWrapAddress(Span(request).subspan(ofs + PCP_REQUEST_HDR_IP_OFS, ADDR_IPV6_SIZE), internal)) return MappingError::NETWORK_ERROR;
442 : :
443 : 0 : ofs += PCP_HDR_SIZE;
444 : :
445 : : // Fill in MAP request packet, See RFC6887 Figure 9.
446 : : // Randomize mapping nonce (this is repeated in the response, to be able to
447 : : // correlate requests and responses, and used to authenticate changes to the mapping).
448 : 0 : std::memcpy(request.data() + ofs + PCP_MAP_NONCE_OFS, nonce.data(), PCP_MAP_NONCE_SIZE);
449 : 0 : request[ofs + PCP_MAP_PROTOCOL_OFS] = PCP_PROTOCOL_TCP;
450 : 0 : WriteBE16(request.data() + ofs + PCP_MAP_INTERNAL_PORT_OFS, port);
451 : 0 : WriteBE16(request.data() + ofs + PCP_MAP_EXTERNAL_PORT_OFS, port);
452 [ # # # # ]: 0 : if (!PCPWrapAddress(Span(request).subspan(ofs + PCP_MAP_EXTERNAL_IP_OFS, ADDR_IPV6_SIZE), bind)) return MappingError::NETWORK_ERROR;
453 : :
454 : 0 : ofs += PCP_MAP_SIZE;
455 [ # # ]: 0 : Assume(ofs == request.size());
456 : :
457 : : // Receive loop.
458 : 0 : bool is_natpmp = false;
459 [ # # ]: 0 : auto recv_res = PCPSendRecv(*sock, "pcp", request, num_tries, timeout_per_try,
460 [ # # ]: 0 : [&](const Span<const uint8_t> response) -> bool {
461 : : // Unsupported version according to RFC6887 appendix A and RFC6886 section 3.5, can fall back to NAT-PMP.
462 [ # # # # : 0 : if (response.size() == NATPMP_RESPONSE_HDR_SIZE && response[PCP_HDR_VERSION_OFS] == NATPMP_VERSION && response[PCP_RESPONSE_HDR_RESULT_OFS] == NATPMP_RESULT_UNSUPP_VERSION) {
# # ]
463 : 0 : is_natpmp = true;
464 : 0 : return true; // Let it through to caller.
465 : : }
466 [ # # ]: 0 : if (response.size() < (PCP_HDR_SIZE + PCP_MAP_SIZE)) {
467 [ # # ]: 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "pcp: Response too small\n");
468 : 0 : return false; // Wasn't response to what we expected, try receiving next packet.
469 : : }
470 [ # # # # ]: 0 : if (response[PCP_HDR_VERSION_OFS] != PCP_VERSION || response[PCP_HDR_OP_OFS] != (PCP_RESPONSE | PCP_OP_MAP)) {
471 [ # # ]: 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "pcp: Response to wrong command\n");
472 : 0 : return false; // Wasn't response to what we expected, try receiving next packet.
473 : : }
474 : : // Handle MAP opcode response. See RFC6887 Figure 10.
475 : : // Check that returned mapping nonce matches our request.
476 [ # # ]: 0 : if (!std::ranges::equal(response.subspan(PCP_HDR_SIZE + PCP_MAP_NONCE_OFS, PCP_MAP_NONCE_SIZE), nonce)) {
477 [ # # ]: 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "pcp: Mapping nonce mismatch\n");
478 : 0 : return false; // Wasn't response to what we expected, try receiving next packet.
479 : : }
480 : 0 : uint8_t protocol = response[PCP_HDR_SIZE + 12];
481 [ # # ]: 0 : uint16_t internal_port = ReadBE16(response.data() + PCP_HDR_SIZE + 16);
482 [ # # # # ]: 0 : if (protocol != PCP_PROTOCOL_TCP || internal_port != port) {
483 [ # # ]: 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "pcp: Response protocol or port doesn't match request\n");
484 : 0 : return false; // Wasn't response to what we expected, try receiving next packet.
485 : : }
486 : : return true;
487 [ # # ]: 0 : });
488 : :
489 [ # # ]: 0 : if (!recv_res) {
490 : 0 : return MappingError::NETWORK_ERROR;
491 : : }
492 [ # # ]: 0 : if (is_natpmp) {
493 : 0 : return MappingError::UNSUPP_VERSION;
494 : : }
495 : :
496 [ # # ]: 0 : const std::span<const uint8_t> response = *recv_res;
497 : : // If we get here, we got a valid MAP response to our request.
498 : : // Check to see if we got the result we expected.
499 [ # # ]: 0 : Assume(response.size() >= (PCP_HDR_SIZE + PCP_MAP_SIZE));
500 : 0 : uint8_t result_code = response[PCP_RESPONSE_HDR_RESULT_OFS];
501 [ # # ]: 0 : uint32_t lifetime_ret = ReadBE32(response.data() + PCP_HDR_LIFETIME_OFS);
502 [ # # ]: 0 : uint16_t external_port = ReadBE16(response.data() + PCP_HDR_SIZE + PCP_MAP_EXTERNAL_PORT_OFS);
503 [ # # ]: 0 : CNetAddr external_addr{PCPUnwrapAddress(response.subspan(PCP_HDR_SIZE + PCP_MAP_EXTERNAL_IP_OFS, ADDR_IPV6_SIZE))};
504 [ # # ]: 0 : if (result_code != PCP_RESULT_SUCCESS) {
505 [ # # # # : 0 : LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "pcp: Mapping failed with result %s\n", PCPResultString(result_code));
# # # # ]
506 [ # # ]: 0 : if (result_code == PCP_RESULT_NO_RESOURCES) {
507 : 0 : return MappingError::NO_RESOURCES;
508 : : }
509 : 0 : return MappingError::PROTOCOL_ERROR;
510 : : }
511 : :
512 [ # # # # ]: 0 : return MappingResult(PCP_VERSION, CService(internal, port), CService(external_addr, external_port), lifetime_ret);
513 : 0 : }
514 : :
515 : 0 : std::string MappingResult::ToString()
516 : : {
517 : 0 : Assume(version == NATPMP_VERSION || version == PCP_VERSION);
518 : 0 : return strprintf("%s:%s -> %s (for %ds)",
519 [ # # ]: 0 : version == NATPMP_VERSION ? "natpmp" : "pcp",
520 [ # # ]: 0 : external.ToStringAddrPort(),
521 : 0 : internal.ToStringAddrPort(),
522 : 0 : lifetime
523 [ # # ]: 0 : );
524 : : }
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