READ THE CODE

Inside Bitcoin

The code behind the network, with room to understand it.

Stable release v32.1bitcoin/bitcoin · f0de87f04062 ↗3,020 source files · 47.5 MB stored on the server340 file guides

Release published 2026-10-28 · Snapshot fetched 2026-11-01. Latest stable release at fetch time; development branches and Git history are excluded. Only the selected code window and visible folders load here.

26,938 bytes · SHA-256 7ed8c053cffc2f29… · View upstream ↗

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 <common/pcp.h>
6
7#include <compat/compat.h>
8#include <crypto/common.h>
9#include <crypto/hex_base.h>
10#include <netaddress.h>
11#include <netbase.h>
12#include <tinyformat.h>
13#include <util/check.h>
14#include <util/log.h>
15#include <util/sock.h>
16#include <util/string.h>
17#include <util/threadinterrupt.h>
18#include <util/time.h>
19
20#include <algorithm>
21#include <atomic>
22#include <compare>
23#include <cstring>
24#include <functional>
25#include <map>
26#include <memory>
27#include <optional>
28#include <span>
29#include <utility>
30#include <vector>
31
32namespace {
33
34// RFC6886 NAT-PMP and RFC6887 Port Control Protocol (PCP) implementation.
35// NAT-PMP and PCP use network byte order (big-endian).
36
37// NAT-PMP (v0) protocol constants.
38//! NAT-PMP uses a fixed server port number (RFC6887 section 1.1).
39constexpr uint16_t NATPMP_SERVER_PORT = 5351;
40//! Version byte for NATPMP (RFC6886 1.1)
41constexpr uint8_t NATPMP_VERSION = 0;
42//! Request opcode base (RFC6886 3).
43constexpr uint8_t NATPMP_REQUEST = 0x00;
44//! Response opcode base (RFC6886 3).
45constexpr uint8_t NATPMP_RESPONSE = 0x80;
46//! Get external address (RFC6886 3.2)
47constexpr uint8_t NATPMP_OP_GETEXTERNAL = 0x00;
48//! Map TCP port (RFC6886 3.3)
49constexpr uint8_t NATPMP_OP_MAP_TCP = 0x02;
50//! Shared request header size in bytes.
51constexpr size_t NATPMP_REQUEST_HDR_SIZE = 2;
52//! Shared response header (minimum) size in bytes.
53constexpr size_t NATPMP_RESPONSE_HDR_SIZE = 8;
54//! GETEXTERNAL request size in bytes, including header (RFC6886 3.2).
55constexpr size_t NATPMP_GETEXTERNAL_REQUEST_SIZE = NATPMP_REQUEST_HDR_SIZE + 0;
56//! GETEXTERNAL response size in bytes, including header (RFC6886 3.2).
57constexpr size_t NATPMP_GETEXTERNAL_RESPONSE_SIZE = NATPMP_RESPONSE_HDR_SIZE + 4;
58//! MAP request size in bytes, including header (RFC6886 3.3).
59constexpr size_t NATPMP_MAP_REQUEST_SIZE = NATPMP_REQUEST_HDR_SIZE + 10;
60//! MAP response size in bytes, including header (RFC6886 3.3).
61constexpr size_t NATPMP_MAP_RESPONSE_SIZE = NATPMP_RESPONSE_HDR_SIZE + 8;
62
63// Shared header offsets (RFC6886 3.2, 3.3), relative to start of packet.
64//!  Offset of version field in packets.
65constexpr size_t NATPMP_HDR_VERSION_OFS = 0;
66//!  Offset of opcode field in packets
67constexpr size_t NATPMP_HDR_OP_OFS = 1;
68//!  Offset of result code in packets. Result codes are 16 bit in NAT-PMP instead of 8 bit in PCP.
69constexpr size_t NATPMP_RESPONSE_HDR_RESULT_OFS = 2;
70
71// GETEXTERNAL response offsets (RFC6886 3.2), relative to start of packet.
72//!  Returned external address
73constexpr size_t NATPMP_GETEXTERNAL_RESPONSE_IP_OFS = 8;
74
75// MAP request offsets (RFC6886 3.3), relative to start of packet.
76//!  Internal port to be mapped.
77constexpr size_t NATPMP_MAP_REQUEST_INTERNAL_PORT_OFS = 4;
78//!  Suggested external port for mapping.
79constexpr size_t NATPMP_MAP_REQUEST_EXTERNAL_PORT_OFS = 6;
80//!  Requested port mapping lifetime in seconds.
81constexpr size_t NATPMP_MAP_REQUEST_LIFETIME_OFS = 8;
82
83// MAP response offsets (RFC6886 3.3), relative to start of packet.
84//!  Internal port for mapping (will match internal port of request).
85constexpr size_t NATPMP_MAP_RESPONSE_INTERNAL_PORT_OFS = 8;
86//!  External port for mapping.
87constexpr size_t NATPMP_MAP_RESPONSE_EXTERNAL_PORT_OFS = 10;
88//!  Created port mapping lifetime in seconds.
89constexpr size_t NATPMP_MAP_RESPONSE_LIFETIME_OFS = 12;
90
91// Relevant NETPMP result codes (RFC6886 3.5).
92//! Result code representing success status.
93constexpr uint8_t NATPMP_RESULT_SUCCESS = 0;
94//! Result code representing unsupported version.
95constexpr uint8_t NATPMP_RESULT_UNSUPP_VERSION = 1;
96//! Result code representing not authorized (router doesn't support port mapping).
97constexpr uint8_t NATPMP_RESULT_NOT_AUTHORIZED = 2;
98//! Result code representing lack of resources.
99constexpr uint8_t NATPMP_RESULT_NO_RESOURCES = 4;
100
101//! Mapping of NATPMP result code to string (RFC6886 3.5). Result codes <=2 match PCP.
102const std::map<uint16_t, std::string> NATPMP_RESULT_STR{
103    {0,  "SUCCESS"},
104    {1,  "UNSUPP_VERSION"},
105    {2,  "NOT_AUTHORIZED"},
106    {3,  "NETWORK_FAILURE"},
107    {4,  "NO_RESOURCES"},
108    {5,  "UNSUPP_OPCODE"},
109};
110
111// PCP (v2) protocol constants.
112//! Maximum packet size in bytes (RFC6887 section 7).
113constexpr size_t PCP_MAX_SIZE = 1100;
114//! PCP uses a fixed server port number (RFC6887 section 19.1). Shared with NAT-PMP.
115constexpr uint16_t PCP_SERVER_PORT = NATPMP_SERVER_PORT;
116//! Version byte. 0 is NAT-PMP (RFC6886), 1 is forbidden, 2 for PCP (RFC6887).
117constexpr uint8_t PCP_VERSION = 2;
118//! PCP Request Header. See RFC6887 section 7.1. Shared with NAT-PMP.
119constexpr uint8_t PCP_REQUEST = NATPMP_REQUEST; // R = 0
120//! PCP Response Header. See RFC6887 section 7.2. Shared with NAT-PMP.
121constexpr uint8_t PCP_RESPONSE = NATPMP_RESPONSE; // R = 1
122//! Map opcode. See RFC6887 section 19.2
123constexpr uint8_t PCP_OP_MAP = 0x01;
124//! TCP protocol number (IANA).
125constexpr uint16_t PCP_PROTOCOL_TCP = 6;
126//! Request and response header size in bytes (RFC6887 section 7.1).
127constexpr size_t PCP_HDR_SIZE = 24;
128//! Map request and response size in bytes (RFC6887 section 11.1).
129constexpr size_t PCP_MAP_SIZE = 36;
130
131// Header offsets shared between request and responses (RFC6887 7.1, 7.2), relative to start of packet.
132//!  Version field (1 byte).
133constexpr size_t PCP_HDR_VERSION_OFS = NATPMP_HDR_VERSION_OFS;
134//!  Opcode field (1 byte).
135constexpr size_t PCP_HDR_OP_OFS = NATPMP_HDR_OP_OFS;
136//!  Requested lifetime (request), granted lifetime (response) (4 bytes).
137constexpr size_t PCP_HDR_LIFETIME_OFS = 4;
138
139// Request header offsets (RFC6887 7.1), relative to start of packet.
140//!  PCP client's IP address (16 bytes).
141constexpr size_t PCP_REQUEST_HDR_IP_OFS = 8;
142
143// Response header offsets (RFC6887 7.2), relative to start of packet.
144//!  Result code (1 byte).
145constexpr size_t PCP_RESPONSE_HDR_RESULT_OFS = 3;
146
147// MAP request/response offsets (RFC6887 11.1), relative to start of opcode-specific data.
148//!  Mapping nonce (12 bytes).
149constexpr size_t PCP_MAP_NONCE_OFS = 0;
150//!  Protocol (1 byte).
151constexpr size_t PCP_MAP_PROTOCOL_OFS = 12;
152//!  Internal port for mapping (2 bytes).
153constexpr size_t PCP_MAP_INTERNAL_PORT_OFS = 16;
154//!  Suggested external port (request), assigned external port (response) (2 bytes).
155constexpr size_t PCP_MAP_EXTERNAL_PORT_OFS = 18;
156//!  Suggested external IP (request), assigned external IP (response) (16 bytes).
157constexpr size_t PCP_MAP_EXTERNAL_IP_OFS = 20;
158
159//! Result code representing success (RFC6887 7.4), shared with NAT-PMP.
160constexpr uint8_t PCP_RESULT_SUCCESS = NATPMP_RESULT_SUCCESS;
161//! Result code representing not authorized (RFC6887 7.4), shared with NAT-PMP.
162constexpr uint8_t PCP_RESULT_NOT_AUTHORIZED = NATPMP_RESULT_NOT_AUTHORIZED;
163//! Result code representing lack of resources (RFC6887 7.4).
164constexpr uint8_t PCP_RESULT_NO_RESOURCES = 8;
165
166//! Mapping of PCP result code to string (RFC6887 7.4). Result codes <=2 match NAT-PMP.
167const std::map<uint8_t, std::string> PCP_RESULT_STR{
168    {0,  "SUCCESS"},
169    {1,  "UNSUPP_VERSION"},
170    {2,  "NOT_AUTHORIZED"},
171    {3,  "MALFORMED_REQUEST"},
172    {4,  "UNSUPP_OPCODE"},
173    {5,  "UNSUPP_OPTION"},
174    {6,  "MALFORMED_OPTION"},
175    {7,  "NETWORK_FAILURE"},
176    {8,  "NO_RESOURCES"},
177    {9,  "UNSUPP_PROTOCOL"},
178    {10, "USER_EX_QUOTA"},
179    {11, "CANNOT_PROVIDE_EXTERNAL"},
180    {12, "ADDRESS_MISMATCH"},
181    {13, "EXCESSIVE_REMOTE_PEER"},
182};
183
184//! Return human-readable string from NATPMP result code.
185std::string NATPMPResultString(uint16_t result_code)
186{
187    auto result_i = NATPMP_RESULT_STR.find(result_code);
188    return strprintf("%s (code %d)", result_i == NATPMP_RESULT_STR.end() ? "(unknown)" : result_i->second,  result_code);
189}
190
191//! Return human-readable string from PCP result code.
192std::string PCPResultString(uint8_t result_code)
193{
194    auto result_i = PCP_RESULT_STR.find(result_code);
195    return strprintf("%s (code %d)", result_i == PCP_RESULT_STR.end() ? "(unknown)" : result_i->second,  result_code);
196}
197
198//! Wrap address in IPv6 according to RFC6887. wrapped_addr needs to be able to store 16 bytes.
199[[nodiscard]] bool PCPWrapAddress(std::span<uint8_t> wrapped_addr, const CNetAddr &addr)
200{
201    Assume(wrapped_addr.size() == ADDR_IPV6_SIZE);
202    if (addr.IsIPv4()) {
203        struct in_addr addr4;
204        if (!addr.GetInAddr(&addr4)) return false;
205        // Section 5: "When the address field holds an IPv4 address, an IPv4-mapped IPv6 address [RFC4291] is used (::ffff:0:0/96)."
206        std::memcpy(wrapped_addr.data(), IPV4_IN_IPV6_PREFIX.data(), IPV4_IN_IPV6_PREFIX.size());
207        std::memcpy(wrapped_addr.data() + IPV4_IN_IPV6_PREFIX.size(), &addr4, ADDR_IPV4_SIZE);
208        return true;
209    } else if (addr.IsIPv6()) {
210        struct in6_addr addr6;
211        if (!addr.GetIn6Addr(&addr6)) return false;
212        std::memcpy(wrapped_addr.data(), &addr6, ADDR_IPV6_SIZE);
213        return true;
214    } else {
215        return false;
216    }
217}
218
219//! Unwrap PCP-encoded address according to RFC6887.
220CNetAddr PCPUnwrapAddress(std::span<const uint8_t> wrapped_addr)
221{
222    Assume(wrapped_addr.size() == ADDR_IPV6_SIZE);
223    if (util::HasPrefix(wrapped_addr, IPV4_IN_IPV6_PREFIX)) {
224        struct in_addr addr4;
225        std::memcpy(&addr4, wrapped_addr.data() + IPV4_IN_IPV6_PREFIX.size(), ADDR_IPV4_SIZE);
226        return CNetAddr(addr4);
227    } else {
228        struct in6_addr addr6;
229        std::memcpy(&addr6, wrapped_addr.data(), ADDR_IPV6_SIZE);
230        return CNetAddr(addr6);
231    }
232}
233
234//! PCP or NAT-PMP send-receive loop.
235std::optional<std::vector<uint8_t>> PCPSendRecv(Sock &sock, const std::string &protocol, std::span<const uint8_t> request, int num_tries,
236        std::chrono::milliseconds timeout_per_try,
237        std::function<bool(std::span<const uint8_t>)> check_packet,
238        CThreadInterrupt& interrupt)
239{
240    using namespace std::chrono;
241    // UDP is a potentially lossy protocol, so we try to send again a few times.
242    uint8_t response[PCP_MAX_SIZE];
243    bool got_response = false;
244    int recvsz = 0;
245    for (int ntry = 0; !got_response && ntry < num_tries; ++ntry) {
246        if (ntry > 0) {
247            LogDebug(BCLog::NET, "%s: Retrying (%d)\n", protocol, ntry);
248        }
249        // Dispatch packet to gateway.
250        if (sock.Send(request.data(), request.size(), 0) != static_cast<ssize_t>(request.size())) {

src/wallet/receive.cpp

src/wallet/coinselection.cpp

src/consensus/validation.h

src/primitives/transaction.cpp

src/script/descriptor.cpp

src/bitcoin-cli.cpp

src/rpc/blockchain.cpp

src/rpc/rawtransaction.cpp

src/init.cpp

src/crypto/sha256.cpp

src/consensus/merkle.h

src/consensus/tx_check.h

src/consensus/tx_verify.h

src/policy/feerate.h

src/policy/feerate.cpp

src/primitives/transaction_identifier.h

src/chainparamsbase.h

src/chainparamsbase.cpp

src/util/moneystr.cpp

src/crypto/ripemd160.h

src/crypto/sha1.h

src/crypto/sha512.h

src/crypto/hmac_sha256.h

src/crypto/hmac_sha512.h

src/crypto/hmac_sha256.cpp

src/crypto/hmac_sha512.cpp

src/crypto/hkdf_sha256_32.h

src/crypto/hkdf_sha256_32.cpp

src/support/cleanse.h

src/support/cleanse.cpp

src/crypto/siphash.cpp

src/crypto/muhash.h

src/crypto/chacha20.h

src/crypto/poly1305.h

src/crypto/chacha20poly1305.h

src/crypto/chacha20poly1305.cpp

src/util/chaintype.cpp

src/util/obfuscation.h

src/util/byte_units.h

src/util/overflow.h

src/blockencodings.cpp

src/net_permissions.cpp

src/policy/packages.cpp

src/policy/rbf.cpp

src/policy/truc_policy.cpp

src/policy/ephemeral_policy.cpp

src/policy/settings.cpp

src/policy/policy.cpp

src/node/transaction.cpp

src/node/coin.cpp

src/rpc/client.cpp

src/rpc/external_signer.cpp

src/rpc/request.cpp

src/rpc/server_util.cpp

src/rpc/fees.cpp

src/rpc/output_script.cpp

src/rpc/rawtransaction_util.cpp

src/rpc/rawtransaction_util.h

src/rpc/register.h

src/rpc/request.h

src/rpc/server_util.h

src/rpc/protocol.h

src/rpc/server.h

src/rpc/signmessage.cpp

src/rpc/txoutproof.cpp

src/rpc/util.cpp

src/rpc/util.h

src/wallet/rpc/addresses.cpp

src/wallet/rpc/backup.cpp

src/wallet/rpc/coins.cpp

src/wallet/rpc/encrypt.cpp

src/wallet/rpc/signmessage.cpp

src/wallet/rpc/util.cpp

src/wallet/rpc/util.h

src/wallet/coincontrol.cpp

src/wallet/coincontrol.h

src/wallet/context.cpp

src/wallet/context.h

src/wallet/crypter.cpp

src/wallet/crypter.h

src/wallet/db.cpp

src/wallet/export.cpp

src/wallet/external_signer_scriptpubkeyman.cpp

src/wallet/rpc/spend.cpp

src/wallet/rpc/transactions.cpp

src/wallet/rpc/wallet.cpp

src/wallet/feebumper.cpp

src/wallet/feebumper.h

src/index/base.h

src/index/base.cpp

src/index/txindex.h

src/index/txindex.cpp

src/index/txindex_key.h

src/index/txospenderindex.h

src/index/txospenderindex.cpp

src/index/blockfilterindex.h

src/index/blockfilterindex.cpp

src/index/coinstatsindex.h

src/index/coinstatsindex.cpp

src/index/db_key.h

src/index/disktxpos.h

src/kernel/chain.cpp

src/kernel/chain.h

src/kernel/checks.cpp

src/kernel/checks.h

src/kernel/context.cpp

src/kernel/context.h

src/kernel/cs_main.cpp

src/kernel/cs_main.h

src/kernel/disconnected_transactions.cpp

src/kernel/disconnected_transactions.h

src/kernel/mempool_removal_reason.cpp

src/kernel/mempool_removal_reason.h

src/kernel/coinstats.cpp

src/kernel/coinstats.h

src/kernel/chainparams.cpp

src/kernel/chainparams.h

src/wallet/sqlite.cpp

src/wallet/sqlite.h

src/wallet/transaction.cpp

src/wallet/transaction.h

src/wallet/dump.cpp

src/wallet/dump.h

src/wallet/init.cpp

src/wallet/walletutil.cpp

src/wallet/walletutil.h

src/wallet/wallettool.cpp

src/wallet/wallettool.h

src/wallet/export.h

src/wallet/migrate.cpp

src/wallet/migrate.h

src/wallet/db.h

src/wallet/walletdb.cpp

src/wallet/interfaces.cpp

src/wallet/scriptpubkeyman.cpp

src/wallet/scriptpubkeyman.h

src/kernel/bitcoinkernel.cpp

src/kernel/bitcoinkernel.h

src/kernel/bitcoinkernel_wrapper.h

src/node/chainstate.cpp

src/node/chainstate.h

src/node/blockstorage.cpp

src/node/blockstorage.h

src/node/mempool_persist.cpp

src/node/mempool_persist.h

src/node/utxo_snapshot.cpp

src/node/utxo_snapshot.h

src/node/kernel_notifications.cpp

src/node/kernel_notifications.h

src/node/blockmanager_args.cpp

src/kernel/blockmanager_opts.h

src/util/expected.cpp

src/policy/settings.h

src/util/types.h

src/kernel/messagestartchars.h

src/kernel/warning.h

src/util/exception.h

src/common/license_info.h

src/node/coins_view_args.h

src/node/database_args.h

src/util/batchpriority.h

src/util/ui_change_type.h

src/node/coins_view_args.cpp

src/node/peerman_args.h

src/util/serfloat.h

src/node/blockmanager_args.h

src/node/database_args.cpp

src/util/overloaded.h

src/interfaces/types.h

src/node/chainstatemanager_args.h

src/node/minisketchwrapper.h

src/util/macros.h

src/util/syserror.h

src/common/run_command.h

src/util/bytevectorhash.cpp

src/node/mempool_persist_args.cpp

src/util/exec.h

src/util/rbf.h

src/crypto/hex_base.h

src/node/mempool_persist_args.h

src/interfaces/echo.h

src/util/any.h

src/util/batchpriority.cpp

src/util/threadnames.h

src/node/coin.h

src/node/mempool_args.h

src/util/asmap.h

src/util/bytevectorhash.h

src/node/context.cpp

src/util/insert.h

src/util/readwritefile.h

src/node/peerman_args.cpp

src/node/interface_ui.cpp

src/interfaces/handler.h

src/node/mining_args.h

src/util/hasher.cpp

src/common/init.h

src/kernel/mempool_limits.h

src/common/system.h

src/crypto/sha3.h

src/util/threadinterrupt.cpp

src/node/protocol_version.h

src/util/exception.cpp

src/common/messages.h

src/node/connection_types.cpp

src/util/bip32.h

src/common/license_info.cpp

src/util/stdmutex.h

src/common/run_command.cpp

src/util/check.cpp

src/util/golombrice.h

src/node/types.h

src/node/timeoffsets.h

src/util/readwritefile.cpp

src/util/fastrange.h

src/util/signalinterrupt.h

src/util/task_runner.h

src/util/syserror.cpp

src/common/interfaces.cpp

src/common/types.h

src/util/threadinterrupt.h

src/kernel/chainstatemanager_opts.h

src/node/psbt.h

src/policy/ephemeral_policy.h

src/util/trace.h

src/common/url.cpp

src/kernel/mempool_options.h

src/util/serfloat.cpp

src/kernel/notifications_interface.h

src/node/timeoffsets.cpp

src/node/warnings.cpp

src/util/hash_type.h

src/crypto/hex_base.cpp

src/node/eviction.h

src/util/tokenbucket.h

src/crypto/aes.h

src/common/pcp.h

src/util/feefrac.cpp

src/node/transaction.h

src/util/threadnames.cpp

src/common/signmessage.h

src/util/exec.cpp

src/util/signalinterrupt.cpp

Independent explanations by MyBitcoinExplorer. Not affiliated with or endorsed by Bitcoin Core. Guides are educational and do not replace the source or its tests.

Bitcoin Core source © its contributors, distributed under the MIT license. Original notices and bundled third-party licenses are retained in the source tree.