1  // Copyright (c) 2015-present The Bitcoin Core developers
  2  // Distributed under the MIT software license, see the accompanying
  3  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  4  
  5  #include <httprpc.h>
  6  
  7  #include <common/args.h>
  8  #include <crypto/hmac_sha256.h>
  9  #include <httpserver.h>
 10  #include <logging.h>
 11  #include <netaddress.h>
 12  #include <rpc/protocol.h>
 13  #include <rpc/server.h>
 14  #include <util/fs.h>
 15  #include <util/fs_helpers.h>
 16  #include <util/strencodings.h>
 17  #include <util/string.h>
 18  #include <walletinitinterface.h>
 19  
 20  #include <algorithm>
 21  #include <iterator>
 22  #include <map>
 23  #include <memory>
 24  #include <optional>
 25  #include <set>
 26  #include <string>
 27  #include <vector>
 28  
 29  using util::SplitString;
 30  using util::TrimStringView;
 31  
 32  /** WWW-Authenticate to present with 401 Unauthorized response */
 33  static const char* WWW_AUTH_HEADER_DATA = "Basic realm=\"jsonrpc\"";
 34  
 35  /* List of -rpcauth values */
 36  static std::vector<std::vector<std::string>> g_rpcauth;
 37  /* RPC Auth Whitelist */
 38  static std::map<std::string, std::set<std::string>> g_rpc_whitelist;
 39  static bool g_rpc_whitelist_default = false;
 40  
 41  static void JSONErrorReply(HTTPRequest* req, UniValue objError, const JSONRPCRequest& jreq)
 42  {
 43      // Sending HTTP errors is a legacy JSON-RPC behavior.
 44      Assume(jreq.m_json_version != JSONRPCVersion::V2);
 45  
 46      // Send error reply from json-rpc error object
 47      int nStatus = HTTP_INTERNAL_SERVER_ERROR;
 48      int code = objError.find_value("code").getInt<int>();
 49  
 50      if (code == RPC_INVALID_REQUEST)
 51          nStatus = HTTP_BAD_REQUEST;
 52      else if (code == RPC_METHOD_NOT_FOUND)
 53          nStatus = HTTP_NOT_FOUND;
 54  
 55      std::string strReply = JSONRPCReplyObj(NullUniValue, std::move(objError), jreq.id, jreq.m_json_version).write() + "\n";
 56  
 57      req->WriteHeader("Content-Type", "application/json");
 58      req->WriteReply(nStatus, strReply);
 59  }
 60  
 61  //This function checks username and password against -rpcauth
 62  //entries from config file.
 63  static bool CheckUserAuthorized(std::string_view user, std::string_view pass)
 64  {
 65      for (const auto& fields : g_rpcauth) {
 66          if (!TimingResistantEqual(std::string_view(fields[0]), user)) {
 67              continue;
 68          }
 69  
 70          const std::string& salt = fields[1];
 71          const std::string& hash = fields[2];
 72  
 73          std::array<unsigned char, CHMAC_SHA256::OUTPUT_SIZE> out;
 74          CHMAC_SHA256(UCharCast(salt.data()), salt.size()).Write(UCharCast(pass.data()), pass.size()).Finalize(out.data());
 75          std::string hash_from_pass = HexStr(out);
 76  
 77          if (TimingResistantEqual(hash_from_pass, hash)) {
 78              return true;
 79          }
 80      }
 81      return false;
 82  }
 83  
 84  static bool RPCAuthorized(const std::string& strAuth, std::string& strAuthUsernameOut)
 85  {
 86      if (!strAuth.starts_with("Basic "))
 87          return false;
 88      std::string_view strUserPass64 = TrimStringView(std::string_view{strAuth}.substr(6));
 89      auto userpass_data = DecodeBase64(strUserPass64);
 90      std::string strUserPass;
 91      if (!userpass_data) return false;
 92      strUserPass.assign(userpass_data->begin(), userpass_data->end());
 93  
 94      size_t colon_pos = strUserPass.find(':');
 95      if (colon_pos == std::string::npos) {
 96          return false; // Invalid basic auth.
 97      }
 98      std::string user = strUserPass.substr(0, colon_pos);
 99      std::string pass = strUserPass.substr(colon_pos + 1);
100      strAuthUsernameOut = user;
101      return CheckUserAuthorized(user, pass);
102  }
103  
104  static bool HTTPReq_JSONRPC(const std::any& context, HTTPRequest* req)
105  {
106      // JSONRPC handles only POST
107      if (req->GetRequestMethod() != HTTPRequest::POST) {
108          req->WriteReply(HTTP_BAD_METHOD, "JSONRPC server handles only POST requests");
109          return false;
110      }
111      // Check authorization
112      std::pair<bool, std::string> authHeader = req->GetHeader("authorization");
113      if (!authHeader.first) {
114          req->WriteHeader("WWW-Authenticate", WWW_AUTH_HEADER_DATA);
115          req->WriteReply(HTTP_UNAUTHORIZED);
116          return false;
117      }
118  
119      JSONRPCRequest jreq;
120      jreq.context = context;
121      jreq.peerAddr = req->GetPeer().ToStringAddrPort();
122      if (!RPCAuthorized(authHeader.second, jreq.authUser)) {
123          LogWarning("ThreadRPCServer incorrect password attempt from %s", jreq.peerAddr);
124  
125          /* Deter brute-forcing
126             If this results in a DoS the user really
127             shouldn't have their RPC port exposed. */
128          UninterruptibleSleep(std::chrono::milliseconds{250});
129  
130          req->WriteHeader("WWW-Authenticate", WWW_AUTH_HEADER_DATA);
131          req->WriteReply(HTTP_UNAUTHORIZED);
132          return false;
133      }
134  
135      try {
136          // Parse request
137          UniValue valRequest;
138          if (!valRequest.read(req->ReadBody()))
139              throw JSONRPCError(RPC_PARSE_ERROR, "Parse error");
140  
141          // Set the URI
142          jreq.URI = req->GetURI();
143  
144          UniValue reply;
145          bool user_has_whitelist = g_rpc_whitelist.contains(jreq.authUser);
146          if (!user_has_whitelist && g_rpc_whitelist_default) {
147              LogWarning("RPC User %s not allowed to call any methods", jreq.authUser);
148              req->WriteReply(HTTP_FORBIDDEN);
149              return false;
150  
151          // singleton request
152          } else if (valRequest.isObject()) {
153              jreq.parse(valRequest);
154              if (user_has_whitelist && !g_rpc_whitelist[jreq.authUser].contains(jreq.strMethod)) {
155                  LogWarning("RPC User %s not allowed to call method %s", jreq.authUser, jreq.strMethod);
156                  req->WriteReply(HTTP_FORBIDDEN);
157                  return false;
158              }
159  
160              // Legacy 1.0/1.1 behavior is for failed requests to throw
161              // exceptions which return HTTP errors and RPC errors to the client.
162              // 2.0 behavior is to catch exceptions and return HTTP success with
163              // RPC errors, as long as there is not an actual HTTP server error.
164              const bool catch_errors{jreq.m_json_version == JSONRPCVersion::V2};
165              reply = JSONRPCExec(jreq, catch_errors);
166  
167              if (jreq.IsNotification()) {
168                  // Even though we do execute notifications, we do not respond to them
169                  req->WriteReply(HTTP_NO_CONTENT);
170                  return true;
171              }
172  
173          // array of requests
174          } else if (valRequest.isArray()) {
175              // Check authorization for each request's method
176              if (user_has_whitelist) {
177                  for (unsigned int reqIdx = 0; reqIdx < valRequest.size(); reqIdx++) {
178                      if (!valRequest[reqIdx].isObject()) {
179                          throw JSONRPCError(RPC_INVALID_REQUEST, "Invalid Request object");
180                      } else {
181                          const UniValue& request = valRequest[reqIdx].get_obj();
182                          // Parse method
183                          std::string strMethod = request.find_value("method").get_str();
184                          if (!g_rpc_whitelist[jreq.authUser].contains(strMethod)) {
185                              LogWarning("RPC User %s not allowed to call method %s", jreq.authUser, strMethod);
186                              req->WriteReply(HTTP_FORBIDDEN);
187                              return false;
188                          }
189                      }
190                  }
191              }
192  
193              // Execute each request
194              reply = UniValue::VARR;
195              for (size_t i{0}; i < valRequest.size(); ++i) {
196                  // Batches never throw HTTP errors, they are always just included
197                  // in "HTTP OK" responses. Notifications never get any response.
198                  UniValue response;
199                  try {
200                      jreq.parse(valRequest[i]);
201                      response = JSONRPCExec(jreq, /*catch_errors=*/true);
202                  } catch (UniValue& e) {
203                      response = JSONRPCReplyObj(NullUniValue, std::move(e), jreq.id, jreq.m_json_version);
204                  } catch (const std::exception& e) {
205                      response = JSONRPCReplyObj(NullUniValue, JSONRPCError(RPC_PARSE_ERROR, e.what()), jreq.id, jreq.m_json_version);
206                  }
207                  if (!jreq.IsNotification()) {
208                      reply.push_back(std::move(response));
209                  }
210              }
211              // Return no response for an all-notification batch, but only if the
212              // batch request is non-empty. Technically according to the JSON-RPC
213              // 2.0 spec, an empty batch request should also return no response,
214              // However, if the batch request is empty, it means the request did
215              // not contain any JSON-RPC version numbers, so returning an empty
216              // response could break backwards compatibility with old RPC clients
217              // relying on previous behavior. Return an empty array instead of an
218              // empty response in this case to favor being backwards compatible
219              // over complying with the JSON-RPC 2.0 spec in this case.
220              if (reply.size() == 0 && valRequest.size() > 0) {
221                  req->WriteReply(HTTP_NO_CONTENT);
222                  return true;
223              }
224          }
225          else
226              throw JSONRPCError(RPC_PARSE_ERROR, "Top-level object parse error");
227  
228          req->WriteHeader("Content-Type", "application/json");
229          req->WriteReply(HTTP_OK, reply.write() + "\n");
230      } catch (UniValue& e) {
231          JSONErrorReply(req, std::move(e), jreq);
232          return false;
233      } catch (const std::exception& e) {
234          JSONErrorReply(req, JSONRPCError(RPC_PARSE_ERROR, e.what()), jreq);
235          return false;
236      }
237      return true;
238  }
239  
240  static bool InitRPCAuthentication()
241  {
242      std::string user;
243      std::string pass;
244  
245      if (gArgs.GetArg("-rpcpassword", "") == "")
246      {
247          std::optional<fs::perms> cookie_perms{std::nullopt};
248          auto cookie_perms_arg{gArgs.GetArg("-rpccookieperms")};
249          if (cookie_perms_arg) {
250              auto perm_opt = InterpretPermString(*cookie_perms_arg);
251              if (!perm_opt) {
252                  LogError("Invalid -rpccookieperms=%s; must be one of 'owner', 'group', or 'all'.", *cookie_perms_arg);
253                  return false;
254              }
255              cookie_perms = *perm_opt;
256          }
257  
258          switch (GenerateAuthCookie(cookie_perms, user, pass)) {
259          case GenerateAuthCookieResult::ERR:
260              return false;
261          case GenerateAuthCookieResult::DISABLED:
262              LogInfo("RPC authentication cookie file generation is disabled.");
263              break;
264          case GenerateAuthCookieResult::OK:
265              LogInfo("Using random cookie authentication.");
266              break;
267          }
268      } else {
269          LogInfo("Using rpcuser/rpcpassword authentication.");
270          LogWarning("The use of rpcuser/rpcpassword is less secure, because credentials are configured in plain text. It is recommended that locally-run instances switch to cookie-based auth, or otherwise to use hashed rpcauth credentials. See share/rpcauth in the source directory for more information.");
271          user = gArgs.GetArg("-rpcuser", "");
272          pass = gArgs.GetArg("-rpcpassword", "");
273      }
274  
275      // If there is a plaintext credential, hash it with a random salt before storage.
276      if (!user.empty() || !pass.empty()) {
277          // Generate a random 16 byte hex salt.
278          std::array<unsigned char, 16> raw_salt;
279          GetStrongRandBytes(raw_salt);
280          std::string salt = HexStr(raw_salt);
281  
282          // Compute HMAC.
283          std::array<unsigned char, CHMAC_SHA256::OUTPUT_SIZE> out;
284          CHMAC_SHA256(UCharCast(salt.data()), salt.size()).Write(UCharCast(pass.data()), pass.size()).Finalize(out.data());
285          std::string hash = HexStr(out);
286  
287          g_rpcauth.push_back({user, salt, hash});
288      }
289  
290      if (!gArgs.GetArgs("-rpcauth").empty()) {
291          LogInfo("Using rpcauth authentication.\n");
292          for (const std::string& rpcauth : gArgs.GetArgs("-rpcauth")) {
293              std::vector<std::string> fields{SplitString(rpcauth, ':')};
294              const std::vector<std::string> salt_hmac{SplitString(fields.back(), '$')};
295              if (fields.size() == 2 && salt_hmac.size() == 2) {
296                  fields.pop_back();
297                  fields.insert(fields.end(), salt_hmac.begin(), salt_hmac.end());
298                  g_rpcauth.push_back(fields);
299              } else {
300                  LogWarning("Invalid -rpcauth argument.");
301                  return false;
302              }
303          }
304      }
305  
306      g_rpc_whitelist_default = gArgs.GetBoolArg("-rpcwhitelistdefault", !gArgs.GetArgs("-rpcwhitelist").empty());
307      for (const std::string& strRPCWhitelist : gArgs.GetArgs("-rpcwhitelist")) {
308          auto pos = strRPCWhitelist.find(':');
309          std::string strUser = strRPCWhitelist.substr(0, pos);
310          bool intersect = g_rpc_whitelist.contains(strUser);
311          std::set<std::string>& whitelist = g_rpc_whitelist[strUser];
312          if (pos != std::string::npos) {
313              std::string strWhitelist = strRPCWhitelist.substr(pos + 1);
314              std::vector<std::string> whitelist_split = SplitString(strWhitelist, ", ");
315              std::set<std::string> new_whitelist{
316                  std::make_move_iterator(whitelist_split.begin()),
317                  std::make_move_iterator(whitelist_split.end())};
318              if (intersect) {
319                  std::set<std::string> tmp_whitelist;
320                  std::set_intersection(new_whitelist.begin(), new_whitelist.end(),
321                         whitelist.begin(), whitelist.end(), std::inserter(tmp_whitelist, tmp_whitelist.end()));
322                  new_whitelist = std::move(tmp_whitelist);
323              }
324              whitelist = std::move(new_whitelist);
325          }
326      }
327  
328      return true;
329  }
330  
331  bool StartHTTPRPC(const std::any& context)
332  {
333      LogDebug(BCLog::RPC, "Starting HTTP RPC server\n");
334      if (!InitRPCAuthentication())
335          return false;
336  
337      auto handle_rpc = [context](HTTPRequest* req, const std::string&) { return HTTPReq_JSONRPC(context, req); };
338      RegisterHTTPHandler("/", true, handle_rpc);
339      if (g_wallet_init_interface.HasWalletSupport()) {
340          RegisterHTTPHandler("/wallet/", false, handle_rpc);
341      }
342      struct event_base* eventBase = EventBase();
343      assert(eventBase);
344      return true;
345  }
346  
347  void InterruptHTTPRPC()
348  {
349      LogDebug(BCLog::RPC, "Interrupting HTTP RPC server\n");
350  }
351  
352  void StopHTTPRPC()
353  {
354      LogDebug(BCLog::RPC, "Stopping HTTP RPC server\n");
355      UnregisterHTTPHandler("/", true);
356      if (g_wallet_init_interface.HasWalletSupport()) {
357          UnregisterHTTPHandler("/wallet/", false);
358      }
359  }