clang-tools  10.0.0
JSONTransport.cpp
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1 //===--- JSONTransport.cpp - sending and receiving LSP messages over JSON -===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 #include "Logger.h"
9 #include "Protocol.h" // For LSPError
10 #include "Shutdown.h"
11 #include "Transport.h"
12 #include "llvm/Support/Errno.h"
13 #include "llvm/Support/Error.h"
14 
15 namespace clang {
16 namespace clangd {
17 namespace {
18 
19 llvm::json::Object encodeError(llvm::Error E) {
20  std::string Message;
22  if (llvm::Error Unhandled = llvm::handleErrors(
23  std::move(E), [&](const LSPError &L) -> llvm::Error {
24  Message = L.Message;
25  Code = L.Code;
26  return llvm::Error::success();
27  }))
28  Message = llvm::toString(std::move(Unhandled));
29 
30  return llvm::json::Object{
31  {"message", std::move(Message)},
32  {"code", int64_t(Code)},
33  };
34 }
35 
36 llvm::Error decodeError(const llvm::json::Object &O) {
37  std::string Msg = O.getString("message").getValueOr("Unspecified error");
38  if (auto Code = O.getInteger("code"))
39  return llvm::make_error<LSPError>(std::move(Msg), ErrorCode(*Code));
40  return llvm::make_error<llvm::StringError>(std::move(Msg),
41  llvm::inconvertibleErrorCode());
42 }
43 
44 class JSONTransport : public Transport {
45 public:
46  JSONTransport(std::FILE *In, llvm::raw_ostream &Out,
47  llvm::raw_ostream *InMirror, bool Pretty, JSONStreamStyle Style)
48  : In(In), Out(Out), InMirror(InMirror ? *InMirror : llvm::nulls()),
49  Pretty(Pretty), Style(Style) {}
50 
51  void notify(llvm::StringRef Method, llvm::json::Value Params) override {
52  sendMessage(llvm::json::Object{
53  {"jsonrpc", "2.0"},
54  {"method", Method},
55  {"params", std::move(Params)},
56  });
57  }
58  void call(llvm::StringRef Method, llvm::json::Value Params,
59  llvm::json::Value ID) override {
60  sendMessage(llvm::json::Object{
61  {"jsonrpc", "2.0"},
62  {"id", std::move(ID)},
63  {"method", Method},
64  {"params", std::move(Params)},
65  });
66  }
67  void reply(llvm::json::Value ID,
68  llvm::Expected<llvm::json::Value> Result) override {
69  if (Result) {
70  sendMessage(llvm::json::Object{
71  {"jsonrpc", "2.0"},
72  {"id", std::move(ID)},
73  {"result", std::move(*Result)},
74  });
75  } else {
76  sendMessage(llvm::json::Object{
77  {"jsonrpc", "2.0"},
78  {"id", std::move(ID)},
79  {"error", encodeError(Result.takeError())},
80  });
81  }
82  }
83 
84  llvm::Error loop(MessageHandler &Handler) override {
85  while (!feof(In)) {
86  if (shutdownRequested())
87  return llvm::createStringError(
88  std::make_error_code(std::errc::operation_canceled),
89  "Got signal, shutting down");
90  if (ferror(In))
91  return llvm::errorCodeToError(
92  std::error_code(errno, std::system_category()));
93  if (auto JSON = readRawMessage()) {
94  if (auto Doc = llvm::json::parse(*JSON)) {
95  vlog(Pretty ? "<<< {0:2}\n" : "<<< {0}\n", *Doc);
96  if (!handleMessage(std::move(*Doc), Handler))
97  return llvm::Error::success(); // we saw the "exit" notification.
98  } else {
99  // Parse error. Log the raw message.
100  vlog("<<< {0}\n", *JSON);
101  elog("JSON parse error: {0}", llvm::toString(Doc.takeError()));
102  }
103  }
104  }
105  return llvm::errorCodeToError(std::make_error_code(std::errc::io_error));
106  }
107 
108 private:
109  // Dispatches incoming message to Handler onNotify/onCall/onReply.
110  bool handleMessage(llvm::json::Value Message, MessageHandler &Handler);
111  // Writes outgoing message to Out stream.
112  void sendMessage(llvm::json::Value Message) {
113  std::string S;
114  llvm::raw_string_ostream OS(S);
115  OS << llvm::formatv(Pretty ? "{0:2}" : "{0}", Message);
116  OS.flush();
117  Out << "Content-Length: " << S.size() << "\r\n\r\n" << S;
118  Out.flush();
119  vlog(">>> {0}\n", S);
120  }
121 
122  // Read raw string messages from input stream.
123  llvm::Optional<std::string> readRawMessage() {
124  return Style == JSONStreamStyle::Delimited ? readDelimitedMessage()
125  : readStandardMessage();
126  }
127  llvm::Optional<std::string> readDelimitedMessage();
128  llvm::Optional<std::string> readStandardMessage();
129 
130  std::FILE *In;
131  llvm::raw_ostream &Out;
132  llvm::raw_ostream &InMirror;
133  bool Pretty;
134  JSONStreamStyle Style;
135 };
136 
137 bool JSONTransport::handleMessage(llvm::json::Value Message,
138  MessageHandler &Handler) {
139  // Message must be an object with "jsonrpc":"2.0".
140  auto *Object = Message.getAsObject();
141  if (!Object ||
142  Object->getString("jsonrpc") != llvm::Optional<llvm::StringRef>("2.0")) {
143  elog("Not a JSON-RPC 2.0 message: {0:2}", Message);
144  return false;
145  }
146  // ID may be any JSON value. If absent, this is a notification.
147  llvm::Optional<llvm::json::Value> ID;
148  if (auto *I = Object->get("id"))
149  ID = std::move(*I);
150  auto Method = Object->getString("method");
151  if (!Method) { // This is a response.
152  if (!ID) {
153  elog("No method and no response ID: {0:2}", Message);
154  return false;
155  }
156  if (auto *Err = Object->getObject("error"))
157  return Handler.onReply(std::move(*ID), decodeError(*Err));
158  // Result should be given, use null if not.
159  llvm::json::Value Result = nullptr;
160  if (auto *R = Object->get("result"))
161  Result = std::move(*R);
162  return Handler.onReply(std::move(*ID), std::move(Result));
163  }
164  // Params should be given, use null if not.
165  llvm::json::Value Params = nullptr;
166  if (auto *P = Object->get("params"))
167  Params = std::move(*P);
168 
169  if (ID)
170  return Handler.onCall(*Method, std::move(Params), std::move(*ID));
171  else
172  return Handler.onNotify(*Method, std::move(Params));
173 }
174 
175 // Tries to read a line up to and including \n.
176 // If failing, feof(), ferror(), or shutdownRequested() will be set.
177 bool readLine(std::FILE *In, std::string &Out) {
178  static constexpr int BufSize = 1024;
179  size_t Size = 0;
180  Out.clear();
181  for (;;) {
182  Out.resize(Size + BufSize);
183  // Handle EINTR which is sent when a debugger attaches on some platforms.
185  nullptr, [&] { return std::fgets(&Out[Size], BufSize, In); }))
186  return false;
187  clearerr(In);
188  // If the line contained null bytes, anything after it (including \n) will
189  // be ignored. Fortunately this is not a legal header or JSON.
190  size_t Read = std::strlen(&Out[Size]);
191  if (Read > 0 && Out[Size + Read - 1] == '\n') {
192  Out.resize(Size + Read);
193  return true;
194  }
195  Size += Read;
196  }
197 }
198 
199 // Returns None when:
200 // - ferror(), feof(), or shutdownRequested() are set.
201 // - Content-Length is missing or empty (protocol error)
202 llvm::Optional<std::string> JSONTransport::readStandardMessage() {
203  // A Language Server Protocol message starts with a set of HTTP headers,
204  // delimited by \r\n, and terminated by an empty line (\r\n).
205  unsigned long long ContentLength = 0;
206  std::string Line;
207  while (true) {
208  if (feof(In) || ferror(In) || !readLine(In, Line))
209  return llvm::None;
210  InMirror << Line;
211 
212  llvm::StringRef LineRef(Line);
213 
214  // We allow comments in headers. Technically this isn't part
215 
216  // of the LSP specification, but makes writing tests easier.
217  if (LineRef.startswith("#"))
218  continue;
219 
220  // Content-Length is a mandatory header, and the only one we handle.
221  if (LineRef.consume_front("Content-Length: ")) {
222  if (ContentLength != 0) {
223  elog("Warning: Duplicate Content-Length header received. "
224  "The previous value for this message ({0}) was ignored.",
225  ContentLength);
226  }
227  llvm::getAsUnsignedInteger(LineRef.trim(), 0, ContentLength);
228  continue;
229  } else if (!LineRef.trim().empty()) {
230  // It's another header, ignore it.
231  continue;
232  } else {
233  // An empty line indicates the end of headers.
234  // Go ahead and read the JSON.
235  break;
236  }
237  }
238 
239  // The fuzzer likes crashing us by sending "Content-Length: 9999999999999999"
240  if (ContentLength > 1 << 30) { // 1024M
241  elog("Refusing to read message with long Content-Length: {0}. "
242  "Expect protocol errors",
243  ContentLength);
244  return llvm::None;
245  }
246  if (ContentLength == 0) {
247  log("Warning: Missing Content-Length header, or zero-length message.");
248  return llvm::None;
249  }
250 
251  std::string JSON(ContentLength, '\0');
252  for (size_t Pos = 0, Read; Pos < ContentLength; Pos += Read) {
253  // Handle EINTR which is sent when a debugger attaches on some platforms.
254  Read = retryAfterSignalUnlessShutdown(0, [&]{
255  return std::fread(&JSON[Pos], 1, ContentLength - Pos, In);
256  });
257  if (Read == 0) {
258  elog("Input was aborted. Read only {0} bytes of expected {1}.", Pos,
259  ContentLength);
260  return llvm::None;
261  }
262  InMirror << llvm::StringRef(&JSON[Pos], Read);
263  clearerr(In); // If we're done, the error was transient. If we're not done,
264  // either it was transient or we'll see it again on retry.
265  Pos += Read;
266  }
267  return std::move(JSON);
268 }
269 
270 // For lit tests we support a simplified syntax:
271 // - messages are delimited by '---' on a line by itself
272 // - lines starting with # are ignored.
273 // This is a testing path, so favor simplicity over performance here.
274 // When returning None, feof(), ferror(), or shutdownRequested() will be set.
275 llvm::Optional<std::string> JSONTransport::readDelimitedMessage() {
276  std::string JSON;
277  std::string Line;
278  while (readLine(In, Line)) {
279  InMirror << Line;
280  auto LineRef = llvm::StringRef(Line).trim();
281  if (LineRef.startswith("#")) // comment
282  continue;
283 
284  // found a delimiter
285  if (LineRef.rtrim() == "---")
286  break;
287 
288  JSON += Line;
289  }
290 
291  if (shutdownRequested())
292  return llvm::None;
293  if (ferror(In)) {
294  elog("Input error while reading message!");
295  return llvm::None;
296  }
297  return std::move(JSON); // Including at EOF
298 }
299 
300 } // namespace
301 
302 std::unique_ptr<Transport> newJSONTransport(std::FILE *In,
303  llvm::raw_ostream &Out,
304  llvm::raw_ostream *InMirror,
305  bool Pretty,
306  JSONStreamStyle Style) {
307  return std::make_unique<JSONTransport>(In, Out, InMirror, Pretty, Style);
308 }
309 
310 } // namespace clangd
311 } // namespace clang
std::string Code
Some operations such as code completion produce a set of candidates.
constexpr llvm::StringLiteral Message
static llvm::StringRef toString(SpecialMemberFunctionsCheck::SpecialMemberFunctionKind K)
Documents should not be synced at all.
void vlog(const char *Fmt, Ts &&... Vals)
Definition: Logger.h:67
void elog(const char *Fmt, Ts &&... Vals)
Definition: Logger.h:56
void handleErrors(llvm::ArrayRef< ClangTidyError > Errors, ClangTidyContext &Context, bool Fix, unsigned &WarningsAsErrorsCount, llvm::IntrusiveRefCntPtr< llvm::vfs::FileSystem > BaseFS)
Displays the found Errors to the users.
Definition: ClangTidy.cpp:568
void log(const char *Fmt, Ts &&... Vals)
Definition: Logger.h:62
std::unique_ptr< Transport > newJSONTransport(std::FILE *In, llvm::raw_ostream &Out, llvm::raw_ostream *InMirror, bool Pretty, JSONStreamStyle Style)
bool shutdownRequested()
Checks whether requestShutdown() was called.
Definition: Shutdown.cpp:34
Position Pos
Definition: SourceCode.cpp:772
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
const Expr * E
Ret retryAfterSignalUnlessShutdown(const typename std::enable_if< true, Ret >::type &Fail, const Fun &F)
Retry an operation if it gets interrupted by a signal.
Definition: Shutdown.h:68