1 //===-- GDBRemoteCommunicationServerPlatform.cpp ----------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "GDBRemoteCommunicationServerPlatform.h"
11 
12 #include <errno.h>
13 
14 #include <chrono>
15 #include <csignal>
16 #include <cstring>
17 #include <mutex>
18 #include <sstream>
19 
20 #include "llvm/Support/FileSystem.h"
21 #include "llvm/Support/Threading.h"
22 
23 #include "lldb/Host/Config.h"
24 #include "lldb/Host/ConnectionFileDescriptor.h"
25 #include "lldb/Host/Host.h"
26 #include "lldb/Host/HostInfo.h"
27 #include "lldb/Target/FileAction.h"
28 #include "lldb/Target/Platform.h"
29 #include "lldb/Target/Process.h"
30 #include "lldb/Target/UnixSignals.h"
31 #include "lldb/Utility/JSON.h"
32 #include "lldb/Utility/Log.h"
33 #include "lldb/Utility/StreamGDBRemote.h"
34 #include "lldb/Utility/StreamString.h"
35 #include "lldb/Utility/StructuredData.h"
36 #include "lldb/Utility/UriParser.h"
37 
38 #include "lldb/Utility/StringExtractorGDBRemote.h"
39 
40 using namespace lldb;
41 using namespace lldb_private;
42 using namespace lldb_private::process_gdb_remote;
43 
44 //----------------------------------------------------------------------
45 // GDBRemoteCommunicationServerPlatform constructor
46 //----------------------------------------------------------------------
47 GDBRemoteCommunicationServerPlatform::GDBRemoteCommunicationServerPlatform(
48     const Socket::SocketProtocol socket_protocol, const char *socket_scheme)
49     : GDBRemoteCommunicationServerCommon("gdb-remote.server",
50                                          "gdb-remote.server.rx_packet"),
51       m_socket_protocol(socket_protocol), m_socket_scheme(socket_scheme),
52       m_spawned_pids_mutex(), m_port_map(), m_port_offset(0) {
53   m_pending_gdb_server.pid = LLDB_INVALID_PROCESS_ID;
54   m_pending_gdb_server.port = 0;
55 
56   RegisterMemberFunctionHandler(
57       StringExtractorGDBRemote::eServerPacketType_qC,
58       &GDBRemoteCommunicationServerPlatform::Handle_qC);
59   RegisterMemberFunctionHandler(
60       StringExtractorGDBRemote::eServerPacketType_qGetWorkingDir,
61       &GDBRemoteCommunicationServerPlatform::Handle_qGetWorkingDir);
62   RegisterMemberFunctionHandler(
63       StringExtractorGDBRemote::eServerPacketType_qLaunchGDBServer,
64       &GDBRemoteCommunicationServerPlatform::Handle_qLaunchGDBServer);
65   RegisterMemberFunctionHandler(
66       StringExtractorGDBRemote::eServerPacketType_qQueryGDBServer,
67       &GDBRemoteCommunicationServerPlatform::Handle_qQueryGDBServer);
68   RegisterMemberFunctionHandler(
69       StringExtractorGDBRemote::eServerPacketType_qKillSpawnedProcess,
70       &GDBRemoteCommunicationServerPlatform::Handle_qKillSpawnedProcess);
71   RegisterMemberFunctionHandler(
72       StringExtractorGDBRemote::eServerPacketType_qProcessInfo,
73       &GDBRemoteCommunicationServerPlatform::Handle_qProcessInfo);
74   RegisterMemberFunctionHandler(
75       StringExtractorGDBRemote::eServerPacketType_QSetWorkingDir,
76       &GDBRemoteCommunicationServerPlatform::Handle_QSetWorkingDir);
77   RegisterMemberFunctionHandler(
78       StringExtractorGDBRemote::eServerPacketType_jSignalsInfo,
79       &GDBRemoteCommunicationServerPlatform::Handle_jSignalsInfo);
80 
81   RegisterPacketHandler(StringExtractorGDBRemote::eServerPacketType_interrupt,
82                         [](StringExtractorGDBRemote packet, Status &error,
83                            bool &interrupt, bool &quit) {
84                           error.SetErrorString("interrupt received");
85                           interrupt = true;
86                           return PacketResult::Success;
87                         });
88 }
89 
90 //----------------------------------------------------------------------
91 // Destructor
92 //----------------------------------------------------------------------
93 GDBRemoteCommunicationServerPlatform::~GDBRemoteCommunicationServerPlatform() {}
94 
95 Status GDBRemoteCommunicationServerPlatform::LaunchGDBServer(
96     const lldb_private::Args &args, std::string hostname, lldb::pid_t &pid,
97     uint16_t &port, std::string &socket_name) {
98   if (port == UINT16_MAX)
99     port = GetNextAvailablePort();
100 
101   // Spawn a new thread to accept the port that gets bound after binding to
102   // port 0 (zero).
103 
104   // ignore the hostname send from the remote end, just use the ip address that
105   // we're currently communicating with as the hostname
106 
107   // Spawn a debugserver and try to get the port it listens to.
108   ProcessLaunchInfo debugserver_launch_info;
109   if (hostname.empty())
110     hostname = "127.0.0.1";
111 
112   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_PLATFORM));
113   if (log)
114     log->Printf("Launching debugserver with: %s:%u...", hostname.c_str(), port);
115 
116   // Do not run in a new session so that it can not linger after the platform
117   // closes.
118   debugserver_launch_info.SetLaunchInSeparateProcessGroup(false);
119   debugserver_launch_info.SetMonitorProcessCallback(
120       std::bind(&GDBRemoteCommunicationServerPlatform::DebugserverProcessReaped,
121                 this, std::placeholders::_1),
122       false);
123 
124   llvm::StringRef platform_scheme;
125   llvm::StringRef platform_ip;
126   int platform_port;
127   llvm::StringRef platform_path;
128   std::string platform_uri = GetConnection()->GetURI();
129   bool ok = UriParser::Parse(platform_uri, platform_scheme, platform_ip,
130                              platform_port, platform_path);
131   UNUSED_IF_ASSERT_DISABLED(ok);
132   assert(ok);
133 
134   std::ostringstream url;
135 // debugserver does not accept the URL scheme prefix.
136 #if !defined(__APPLE__)
137   url << m_socket_scheme << "://";
138 #endif
139   uint16_t *port_ptr = &port;
140   if (m_socket_protocol == Socket::ProtocolTcp)
141     url << platform_ip.str() << ":" << port;
142   else {
143     socket_name = GetDomainSocketPath("gdbserver").GetPath();
144     url << socket_name;
145     port_ptr = nullptr;
146   }
147 
148   Status error = StartDebugserverProcess(
149       url.str().c_str(), nullptr, debugserver_launch_info, port_ptr, &args, -1);
150 
151   pid = debugserver_launch_info.GetProcessID();
152   if (pid != LLDB_INVALID_PROCESS_ID) {
153     std::lock_guard<std::recursive_mutex> guard(m_spawned_pids_mutex);
154     m_spawned_pids.insert(pid);
155     if (port > 0)
156       AssociatePortWithProcess(port, pid);
157   } else {
158     if (port > 0)
159       FreePort(port);
160   }
161   return error;
162 }
163 
164 GDBRemoteCommunication::PacketResult
165 GDBRemoteCommunicationServerPlatform::Handle_qLaunchGDBServer(
166     StringExtractorGDBRemote &packet) {
167   // Spawn a local debugserver as a platform so we can then attach or launch a
168   // process...
169 
170   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_PLATFORM));
171   if (log)
172     log->Printf("GDBRemoteCommunicationServerPlatform::%s() called",
173                 __FUNCTION__);
174 
175   ConnectionFileDescriptor file_conn;
176   std::string hostname;
177   packet.SetFilePos(::strlen("qLaunchGDBServer;"));
178   llvm::StringRef name;
179   llvm::StringRef value;
180   uint16_t port = UINT16_MAX;
181   while (packet.GetNameColonValue(name, value)) {
182     if (name.equals("host"))
183       hostname = value;
184     else if (name.equals("port"))
185       value.getAsInteger(0, port);
186   }
187 
188   lldb::pid_t debugserver_pid = LLDB_INVALID_PROCESS_ID;
189   std::string socket_name;
190   Status error =
191       LaunchGDBServer(Args(), hostname, debugserver_pid, port, socket_name);
192   if (error.Fail()) {
193     if (log)
194       log->Printf("GDBRemoteCommunicationServerPlatform::%s() debugserver "
195                   "launch failed: %s",
196                   __FUNCTION__, error.AsCString());
197     return SendErrorResponse(9);
198   }
199 
200   if (log)
201     log->Printf("GDBRemoteCommunicationServerPlatform::%s() debugserver "
202                 "launched successfully as pid %" PRIu64,
203                 __FUNCTION__, debugserver_pid);
204 
205   StreamGDBRemote response;
206   response.Printf("pid:%" PRIu64 ";port:%u;", debugserver_pid,
207                   port + m_port_offset);
208   if (!socket_name.empty()) {
209     response.PutCString("socket_name:");
210     response.PutCStringAsRawHex8(socket_name.c_str());
211     response.PutChar(';');
212   }
213 
214   PacketResult packet_result = SendPacketNoLock(response.GetString());
215   if (packet_result != PacketResult::Success) {
216     if (debugserver_pid != LLDB_INVALID_PROCESS_ID)
217       Host::Kill(debugserver_pid, SIGINT);
218   }
219   return packet_result;
220 }
221 
222 GDBRemoteCommunication::PacketResult
223 GDBRemoteCommunicationServerPlatform::Handle_qQueryGDBServer(
224     StringExtractorGDBRemote &packet) {
225   if (m_pending_gdb_server.pid == LLDB_INVALID_PROCESS_ID)
226     return SendErrorResponse(4);
227 
228   JSONObject::SP server_sp = std::make_shared<JSONObject>();
229   server_sp->SetObject("port",
230                        std::make_shared<JSONNumber>(m_pending_gdb_server.port));
231   if (!m_pending_gdb_server.socket_name.empty())
232     server_sp->SetObject(
233         "socket_name",
234         std::make_shared<JSONString>(m_pending_gdb_server.socket_name.c_str()));
235 
236   JSONArray server_list;
237   server_list.AppendObject(server_sp);
238 
239   StreamGDBRemote response;
240   server_list.Write(response);
241 
242   StreamGDBRemote escaped_response;
243   escaped_response.PutEscapedBytes(response.GetString().data(),
244                                    response.GetSize());
245   return SendPacketNoLock(escaped_response.GetString());
246 }
247 
248 GDBRemoteCommunication::PacketResult
249 GDBRemoteCommunicationServerPlatform::Handle_qKillSpawnedProcess(
250     StringExtractorGDBRemote &packet) {
251   packet.SetFilePos(::strlen("qKillSpawnedProcess:"));
252 
253   lldb::pid_t pid = packet.GetU64(LLDB_INVALID_PROCESS_ID);
254 
255   // verify that we know anything about this pid. Scope for locker
256   {
257     std::lock_guard<std::recursive_mutex> guard(m_spawned_pids_mutex);
258     if (m_spawned_pids.find(pid) == m_spawned_pids.end()) {
259       // not a pid we know about
260       return SendErrorResponse(10);
261     }
262   }
263 
264   // go ahead and attempt to kill the spawned process
265   if (KillSpawnedProcess(pid))
266     return SendOKResponse();
267   else
268     return SendErrorResponse(11);
269 }
270 
271 bool GDBRemoteCommunicationServerPlatform::KillSpawnedProcess(lldb::pid_t pid) {
272   // make sure we know about this process
273   {
274     std::lock_guard<std::recursive_mutex> guard(m_spawned_pids_mutex);
275     if (m_spawned_pids.find(pid) == m_spawned_pids.end())
276       return false;
277   }
278 
279   // first try a SIGTERM (standard kill)
280   Host::Kill(pid, SIGTERM);
281 
282   // check if that worked
283   for (size_t i = 0; i < 10; ++i) {
284     {
285       std::lock_guard<std::recursive_mutex> guard(m_spawned_pids_mutex);
286       if (m_spawned_pids.find(pid) == m_spawned_pids.end()) {
287         // it is now killed
288         return true;
289       }
290     }
291     usleep(10000);
292   }
293 
294   // check one more time after the final usleep
295   {
296     std::lock_guard<std::recursive_mutex> guard(m_spawned_pids_mutex);
297     if (m_spawned_pids.find(pid) == m_spawned_pids.end())
298       return true;
299   }
300 
301   // the launched process still lives.  Now try killing it again, this time
302   // with an unblockable signal.
303   Host::Kill(pid, SIGKILL);
304 
305   for (size_t i = 0; i < 10; ++i) {
306     {
307       std::lock_guard<std::recursive_mutex> guard(m_spawned_pids_mutex);
308       if (m_spawned_pids.find(pid) == m_spawned_pids.end()) {
309         // it is now killed
310         return true;
311       }
312     }
313     usleep(10000);
314   }
315 
316   // check one more time after the final usleep Scope for locker
317   {
318     std::lock_guard<std::recursive_mutex> guard(m_spawned_pids_mutex);
319     if (m_spawned_pids.find(pid) == m_spawned_pids.end())
320       return true;
321   }
322 
323   // no luck - the process still lives
324   return false;
325 }
326 
327 GDBRemoteCommunication::PacketResult
328 GDBRemoteCommunicationServerPlatform::Handle_qProcessInfo(
329     StringExtractorGDBRemote &packet) {
330   lldb::pid_t pid = m_process_launch_info.GetProcessID();
331   m_process_launch_info.Clear();
332 
333   if (pid == LLDB_INVALID_PROCESS_ID)
334     return SendErrorResponse(1);
335 
336   ProcessInstanceInfo proc_info;
337   if (!Host::GetProcessInfo(pid, proc_info))
338     return SendErrorResponse(1);
339 
340   StreamString response;
341   CreateProcessInfoResponse_DebugServerStyle(proc_info, response);
342   return SendPacketNoLock(response.GetString());
343 }
344 
345 GDBRemoteCommunication::PacketResult
346 GDBRemoteCommunicationServerPlatform::Handle_qGetWorkingDir(
347     StringExtractorGDBRemote &packet) {
348 
349   llvm::SmallString<64> cwd;
350   if (std::error_code ec = llvm::sys::fs::current_path(cwd))
351     return SendErrorResponse(ec.value());
352 
353   StreamString response;
354   response.PutBytesAsRawHex8(cwd.data(), cwd.size());
355   return SendPacketNoLock(response.GetString());
356 }
357 
358 GDBRemoteCommunication::PacketResult
359 GDBRemoteCommunicationServerPlatform::Handle_QSetWorkingDir(
360     StringExtractorGDBRemote &packet) {
361   packet.SetFilePos(::strlen("QSetWorkingDir:"));
362   std::string path;
363   packet.GetHexByteString(path);
364 
365   if (std::error_code ec = llvm::sys::fs::set_current_path(path))
366     return SendErrorResponse(ec.value());
367   return SendOKResponse();
368 }
369 
370 GDBRemoteCommunication::PacketResult
371 GDBRemoteCommunicationServerPlatform::Handle_qC(
372     StringExtractorGDBRemote &packet) {
373   // NOTE: lldb should now be using qProcessInfo for process IDs.  This path
374   // here
375   // should not be used.  It is reporting process id instead of thread id.  The
376   // correct answer doesn't seem to make much sense for lldb-platform.
377   // CONSIDER: flip to "unsupported".
378   lldb::pid_t pid = m_process_launch_info.GetProcessID();
379 
380   StreamString response;
381   response.Printf("QC%" PRIx64, pid);
382 
383   // If we launch a process and this GDB server is acting as a platform, then
384   // we need to clear the process launch state so we can start launching
385   // another process. In order to launch a process a bunch or packets need to
386   // be sent: environment packets, working directory, disable ASLR, and many
387   // more settings. When we launch a process we then need to know when to clear
388   // this information. Currently we are selecting the 'qC' packet as that
389   // packet which seems to make the most sense.
390   if (pid != LLDB_INVALID_PROCESS_ID) {
391     m_process_launch_info.Clear();
392   }
393 
394   return SendPacketNoLock(response.GetString());
395 }
396 
397 GDBRemoteCommunication::PacketResult
398 GDBRemoteCommunicationServerPlatform::Handle_jSignalsInfo(
399     StringExtractorGDBRemote &packet) {
400   StructuredData::Array signal_array;
401 
402   const auto &signals = Host::GetUnixSignals();
403   for (auto signo = signals->GetFirstSignalNumber();
404        signo != LLDB_INVALID_SIGNAL_NUMBER;
405        signo = signals->GetNextSignalNumber(signo)) {
406     auto dictionary = std::make_shared<StructuredData::Dictionary>();
407 
408     dictionary->AddIntegerItem("signo", signo);
409     dictionary->AddStringItem("name", signals->GetSignalAsCString(signo));
410 
411     bool suppress, stop, notify;
412     signals->GetSignalInfo(signo, suppress, stop, notify);
413     dictionary->AddBooleanItem("suppress", suppress);
414     dictionary->AddBooleanItem("stop", stop);
415     dictionary->AddBooleanItem("notify", notify);
416 
417     signal_array.Push(dictionary);
418   }
419 
420   StreamString response;
421   signal_array.Dump(response);
422   return SendPacketNoLock(response.GetString());
423 }
424 
425 bool GDBRemoteCommunicationServerPlatform::DebugserverProcessReaped(
426     lldb::pid_t pid) {
427   std::lock_guard<std::recursive_mutex> guard(m_spawned_pids_mutex);
428   FreePortForProcess(pid);
429   m_spawned_pids.erase(pid);
430   return true;
431 }
432 
433 Status GDBRemoteCommunicationServerPlatform::LaunchProcess() {
434   if (!m_process_launch_info.GetArguments().GetArgumentCount())
435     return Status("%s: no process command line specified to launch",
436                   __FUNCTION__);
437 
438   // specify the process monitor if not already set.  This should generally be
439   // what happens since we need to reap started processes.
440   if (!m_process_launch_info.GetMonitorProcessCallback())
441     m_process_launch_info.SetMonitorProcessCallback(
442         std::bind(
443             &GDBRemoteCommunicationServerPlatform::DebugserverProcessReaped,
444             this, std::placeholders::_1),
445         false);
446 
447   Status error = Host::LaunchProcess(m_process_launch_info);
448   if (!error.Success()) {
449     fprintf(stderr, "%s: failed to launch executable %s", __FUNCTION__,
450             m_process_launch_info.GetArguments().GetArgumentAtIndex(0));
451     return error;
452   }
453 
454   printf("Launched '%s' as process %" PRIu64 "...\n",
455          m_process_launch_info.GetArguments().GetArgumentAtIndex(0),
456          m_process_launch_info.GetProcessID());
457 
458   // add to list of spawned processes.  On an lldb-gdbserver, we would expect
459   // there to be only one.
460   const auto pid = m_process_launch_info.GetProcessID();
461   if (pid != LLDB_INVALID_PROCESS_ID) {
462     // add to spawned pids
463     std::lock_guard<std::recursive_mutex> guard(m_spawned_pids_mutex);
464     m_spawned_pids.insert(pid);
465   }
466 
467   return error;
468 }
469 
470 void GDBRemoteCommunicationServerPlatform::SetPortMap(PortMap &&port_map) {
471   m_port_map = port_map;
472 }
473 
474 uint16_t GDBRemoteCommunicationServerPlatform::GetNextAvailablePort() {
475   if (m_port_map.empty())
476     return 0; // Bind to port zero and get a port, we didn't have any
477               // limitations
478 
479   for (auto &pair : m_port_map) {
480     if (pair.second == LLDB_INVALID_PROCESS_ID) {
481       pair.second = ~(lldb::pid_t)LLDB_INVALID_PROCESS_ID;
482       return pair.first;
483     }
484   }
485   return UINT16_MAX;
486 }
487 
488 bool GDBRemoteCommunicationServerPlatform::AssociatePortWithProcess(
489     uint16_t port, lldb::pid_t pid) {
490   PortMap::iterator pos = m_port_map.find(port);
491   if (pos != m_port_map.end()) {
492     pos->second = pid;
493     return true;
494   }
495   return false;
496 }
497 
498 bool GDBRemoteCommunicationServerPlatform::FreePort(uint16_t port) {
499   PortMap::iterator pos = m_port_map.find(port);
500   if (pos != m_port_map.end()) {
501     pos->second = LLDB_INVALID_PROCESS_ID;
502     return true;
503   }
504   return false;
505 }
506 
507 bool GDBRemoteCommunicationServerPlatform::FreePortForProcess(lldb::pid_t pid) {
508   if (!m_port_map.empty()) {
509     for (auto &pair : m_port_map) {
510       if (pair.second == pid) {
511         pair.second = LLDB_INVALID_PROCESS_ID;
512         return true;
513       }
514     }
515   }
516   return false;
517 }
518 
519 const FileSpec &GDBRemoteCommunicationServerPlatform::GetDomainSocketDir() {
520   static FileSpec g_domainsocket_dir;
521   static llvm::once_flag g_once_flag;
522 
523   llvm::call_once(g_once_flag, []() {
524     const char *domainsocket_dir_env =
525         ::getenv("LLDB_DEBUGSERVER_DOMAINSOCKET_DIR");
526     if (domainsocket_dir_env != nullptr)
527       g_domainsocket_dir = FileSpec(domainsocket_dir_env);
528     else
529       g_domainsocket_dir = HostInfo::GetProcessTempDir();
530   });
531 
532   return g_domainsocket_dir;
533 }
534 
535 FileSpec
536 GDBRemoteCommunicationServerPlatform::GetDomainSocketPath(const char *prefix) {
537   llvm::SmallString<128> socket_path;
538   llvm::SmallString<128> socket_name(
539       (llvm::StringRef(prefix) + ".%%%%%%").str());
540 
541   FileSpec socket_path_spec(GetDomainSocketDir());
542   socket_path_spec.AppendPathComponent(socket_name.c_str());
543 
544   llvm::sys::fs::createUniqueFile(socket_path_spec.GetCString(), socket_path);
545   return FileSpec(socket_path.c_str());
546 }
547 
548 void GDBRemoteCommunicationServerPlatform::SetPortOffset(uint16_t port_offset) {
549   m_port_offset = port_offset;
550 }
551 
552 void GDBRemoteCommunicationServerPlatform::SetPendingGdbServer(
553     lldb::pid_t pid, uint16_t port, const std::string &socket_name) {
554   m_pending_gdb_server.pid = pid;
555   m_pending_gdb_server.port = port;
556   m_pending_gdb_server.socket_name = socket_name;
557 }
558