1//===-- GDBRemoteCommunication.cpp ----------------------------------------===//
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
9#include "GDBRemoteCommunication.h"
10#include "ProcessGDBRemoteLog.h"
11#include "lldb/Host/Config.h"
12#include "lldb/Host/FileSystem.h"
13#include "lldb/Host/Host.h"
14#include "lldb/Host/Pipe.h"
15#include "lldb/Host/ProcessLaunchInfo.h"
16#include "lldb/Host/Socket.h"
17#include "lldb/Host/common/TCPSocket.h"
18#include "lldb/Host/posix/ConnectionFileDescriptorPosix.h"
19#include "lldb/Target/Platform.h"
20#include "lldb/Utility/Event.h"
21#include "lldb/Utility/FileSpec.h"
22#include "lldb/Utility/Log.h"
23#include "lldb/Utility/RegularExpression.h"
24#include "lldb/Utility/StreamString.h"
25#include "llvm/ADT/SmallString.h"
26#include "llvm/ADT/StringRef.h"
27#include "llvm/Config/llvm-config.h" // for LLVM_ENABLE_ZLIB
28#include "llvm/Support/Error.h"
29#include "llvm/Support/ScopedPrinter.h"
30#include <climits>
31#include <cstring>
32#include <sys/stat.h>
33#include <variant>
34
35#if HAVE_LIBCOMPRESSION
36#include <compression.h>
37#endif
38
39#if LLVM_ENABLE_ZLIB
40#include <zlib.h>
41#endif
42
43using namespace lldb;
44using namespace lldb_private;
45using namespace lldb_private::process_gdb_remote;
46
47// GDBRemoteCommunication constructor
48GDBRemoteCommunication::GDBRemoteCommunication()
49 : Communication(),
50#ifdef LLDB_CONFIGURATION_DEBUG
51 m_packet_timeout(1000),
52#else
53 m_packet_timeout(1),
54#endif
55 m_echo_number(0), m_supports_qEcho(eLazyBoolCalculate), m_history(512),
56 m_send_acks(true), m_is_platform(false),
57 m_compression_type(CompressionType::None) {
58}
59
60// Destructor
61GDBRemoteCommunication::~GDBRemoteCommunication() {
62 if (IsConnected()) {
63 Disconnect();
64 }
65
66#if HAVE_LIBCOMPRESSION
67 if (m_decompression_scratch)
68 free (m_decompression_scratch);
69#endif
70}
71
72char GDBRemoteCommunication::CalculcateChecksum(llvm::StringRef payload) {
73 int checksum = 0;
74
75 for (char c : payload)
76 checksum += c;
77
78 return checksum & 255;
79}
80
81size_t GDBRemoteCommunication::SendAck() {
82 Log *log = GetLog(mask: GDBRLog::Packets);
83 ConnectionStatus status = eConnectionStatusSuccess;
84 char ch = '+';
85 const size_t bytes_written = WriteAll(src: &ch, src_len: 1, status, error_ptr: nullptr);
86 LLDB_LOGF(log, "<%4" PRIu64 "> send packet: %c", (uint64_t)bytes_written, ch);
87 m_history.AddPacket(packet_char: ch, type: GDBRemotePacket::ePacketTypeSend, bytes_transmitted: bytes_written);
88 return bytes_written;
89}
90
91size_t GDBRemoteCommunication::SendNack() {
92 Log *log = GetLog(mask: GDBRLog::Packets);
93 ConnectionStatus status = eConnectionStatusSuccess;
94 char ch = '-';
95 const size_t bytes_written = WriteAll(src: &ch, src_len: 1, status, error_ptr: nullptr);
96 LLDB_LOGF(log, "<%4" PRIu64 "> send packet: %c", (uint64_t)bytes_written, ch);
97 m_history.AddPacket(packet_char: ch, type: GDBRemotePacket::ePacketTypeSend, bytes_transmitted: bytes_written);
98 return bytes_written;
99}
100
101GDBRemoteCommunication::PacketResult
102GDBRemoteCommunication::SendPacketNoLock(llvm::StringRef payload) {
103 StreamString packet(0, 4, eByteOrderBig);
104 packet.PutChar(ch: '$');
105 packet.Write(src: payload.data(), src_len: payload.size());
106 packet.PutChar(ch: '#');
107 packet.PutHex8(uvalue: CalculcateChecksum(payload));
108 std::string packet_str = std::string(packet.GetString());
109
110 return SendRawPacketNoLock(payload: packet_str);
111}
112
113GDBRemoteCommunication::PacketResult
114GDBRemoteCommunication::SendNotificationPacketNoLock(
115 llvm::StringRef notify_type, std::deque<std::string> &queue,
116 llvm::StringRef payload) {
117 PacketResult ret = PacketResult::Success;
118
119 // If there are no notification in the queue, send the notification
120 // packet.
121 if (queue.empty()) {
122 StreamString packet(0, 4, eByteOrderBig);
123 packet.PutChar(ch: '%');
124 packet.Write(src: notify_type.data(), src_len: notify_type.size());
125 packet.PutChar(ch: ':');
126 packet.Write(src: payload.data(), src_len: payload.size());
127 packet.PutChar(ch: '#');
128 packet.PutHex8(uvalue: CalculcateChecksum(payload));
129 ret = SendRawPacketNoLock(payload: packet.GetString(), skip_ack: true);
130 }
131
132 queue.push_back(x: payload.str());
133 return ret;
134}
135
136GDBRemoteCommunication::PacketResult
137GDBRemoteCommunication::SendRawPacketNoLock(llvm::StringRef packet,
138 bool skip_ack) {
139 if (IsConnected()) {
140 Log *log = GetLog(mask: GDBRLog::Packets);
141 ConnectionStatus status = eConnectionStatusSuccess;
142 const char *packet_data = packet.data();
143 const size_t packet_length = packet.size();
144 size_t bytes_written = WriteAll(src: packet_data, src_len: packet_length, status, error_ptr: nullptr);
145 if (log) {
146 size_t binary_start_offset = 0;
147 if (strncmp(s1: packet_data, s2: "$vFile:pwrite:", n: strlen(s: "$vFile:pwrite:")) ==
148 0) {
149 const char *first_comma = strchr(s: packet_data, c: ',');
150 if (first_comma) {
151 const char *second_comma = strchr(s: first_comma + 1, c: ',');
152 if (second_comma)
153 binary_start_offset = second_comma - packet_data + 1;
154 }
155 }
156
157 // If logging was just enabled and we have history, then dump out what we
158 // have to the log so we get the historical context. The Dump() call that
159 // logs all of the packet will set a boolean so that we don't dump this
160 // more than once
161 if (!m_history.DidDumpToLog())
162 m_history.Dump(log);
163
164 if (binary_start_offset) {
165 StreamString strm;
166 // Print non binary data header
167 strm.Printf(format: "<%4" PRIu64 "> send packet: %.*s", (uint64_t)bytes_written,
168 (int)binary_start_offset, packet_data);
169 const uint8_t *p;
170 // Print binary data exactly as sent
171 for (p = (const uint8_t *)packet_data + binary_start_offset; *p != '#';
172 ++p)
173 strm.Printf(format: "\\x%2.2x", *p);
174 // Print the checksum
175 strm.Printf(format: "%*s", (int)3, p);
176 log->PutString(str: strm.GetString());
177 } else
178 LLDB_LOGF(log, "<%4" PRIu64 "> send packet: %.*s",
179 (uint64_t)bytes_written, (int)packet_length, packet_data);
180 }
181
182 m_history.AddPacket(src: packet.str(), src_len: packet_length,
183 type: GDBRemotePacket::ePacketTypeSend, bytes_transmitted: bytes_written);
184
185 if (bytes_written == packet_length) {
186 if (!skip_ack && GetSendAcks())
187 return GetAck();
188 else
189 return PacketResult::Success;
190 } else {
191 LLDB_LOGF(log, "error: failed to send packet: %.*s", (int)packet_length,
192 packet_data);
193 }
194 }
195 return PacketResult::ErrorSendFailed;
196}
197
198GDBRemoteCommunication::PacketResult GDBRemoteCommunication::GetAck() {
199 StringExtractorGDBRemote packet;
200 PacketResult result = WaitForPacketNoLock(response&: packet, timeout: GetPacketTimeout(), sync_on_timeout: false);
201 if (result == PacketResult::Success) {
202 if (packet.GetResponseType() ==
203 StringExtractorGDBRemote::ResponseType::eAck)
204 return PacketResult::Success;
205 else
206 return PacketResult::ErrorSendAck;
207 }
208 return result;
209}
210
211GDBRemoteCommunication::PacketResult
212GDBRemoteCommunication::ReadPacket(StringExtractorGDBRemote &response,
213 Timeout<std::micro> timeout,
214 bool sync_on_timeout) {
215 using ResponseType = StringExtractorGDBRemote::ResponseType;
216
217 Log *log = GetLog(mask: GDBRLog::Packets);
218 for (;;) {
219 PacketResult result =
220 WaitForPacketNoLock(response, timeout, sync_on_timeout);
221 if (result != PacketResult::Success ||
222 (response.GetResponseType() != ResponseType::eAck &&
223 response.GetResponseType() != ResponseType::eNack))
224 return result;
225 LLDB_LOG(log, "discarding spurious `{0}` packet", response.GetStringRef());
226 }
227}
228
229GDBRemoteCommunication::PacketResult
230GDBRemoteCommunication::WaitForPacketNoLock(StringExtractorGDBRemote &packet,
231 Timeout<std::micro> timeout,
232 bool sync_on_timeout) {
233 uint8_t buffer[8192];
234 Status error;
235
236 Log *log = GetLog(mask: GDBRLog::Packets);
237
238 // Check for a packet from our cache first without trying any reading...
239 if (CheckForPacket(src: nullptr, src_len: 0, packet) != PacketType::Invalid)
240 return PacketResult::Success;
241
242 bool timed_out = false;
243 bool disconnected = false;
244 while (IsConnected() && !timed_out) {
245 lldb::ConnectionStatus status = eConnectionStatusNoConnection;
246 size_t bytes_read = Read(dst: buffer, dst_len: sizeof(buffer), timeout, status, error_ptr: &error);
247
248 LLDB_LOGV(log,
249 "Read(buffer, sizeof(buffer), timeout = {0}, "
250 "status = {1}, error = {2}) => bytes_read = {3}",
251 timeout, Communication::ConnectionStatusAsString(status), error,
252 bytes_read);
253
254 if (bytes_read > 0) {
255 if (CheckForPacket(src: buffer, src_len: bytes_read, packet) != PacketType::Invalid)
256 return PacketResult::Success;
257 } else {
258 switch (status) {
259 case eConnectionStatusTimedOut:
260 case eConnectionStatusInterrupted:
261 if (sync_on_timeout) {
262 /// Sync the remote GDB server and make sure we get a response that
263 /// corresponds to what we send.
264 ///
265 /// Sends a "qEcho" packet and makes sure it gets the exact packet
266 /// echoed back. If the qEcho packet isn't supported, we send a qC
267 /// packet and make sure we get a valid thread ID back. We use the
268 /// "qC" packet since its response if very unique: is responds with
269 /// "QC%x" where %x is the thread ID of the current thread. This
270 /// makes the response unique enough from other packet responses to
271 /// ensure we are back on track.
272 ///
273 /// This packet is needed after we time out sending a packet so we
274 /// can ensure that we are getting the response for the packet we
275 /// are sending. There are no sequence IDs in the GDB remote
276 /// protocol (there used to be, but they are not supported anymore)
277 /// so if you timeout sending packet "abc", you might then send
278 /// packet "cde" and get the response for the previous "abc" packet.
279 /// Many responses are "OK" or "" (unsupported) or "EXX" (error) so
280 /// many responses for packets can look like responses for other
281 /// packets. So if we timeout, we need to ensure that we can get
282 /// back on track. If we can't get back on track, we must
283 /// disconnect.
284 bool sync_success = false;
285 bool got_actual_response = false;
286 // We timed out, we need to sync back up with the
287 char echo_packet[32];
288 int echo_packet_len = 0;
289 RegularExpression response_regex;
290
291 if (m_supports_qEcho == eLazyBoolYes) {
292 echo_packet_len = ::snprintf(s: echo_packet, maxlen: sizeof(echo_packet),
293 format: "qEcho:%u", ++m_echo_number);
294 std::string regex_str = "^";
295 regex_str += echo_packet;
296 regex_str += "$";
297 response_regex = RegularExpression(regex_str);
298 } else {
299 echo_packet_len =
300 ::snprintf(s: echo_packet, maxlen: sizeof(echo_packet), format: "qC");
301 response_regex =
302 RegularExpression(llvm::StringRef("^QC[0-9A-Fa-f]+$"));
303 }
304
305 PacketResult echo_packet_result =
306 SendPacketNoLock(payload: llvm::StringRef(echo_packet, echo_packet_len));
307 if (echo_packet_result == PacketResult::Success) {
308 const uint32_t max_retries = 3;
309 uint32_t successful_responses = 0;
310 for (uint32_t i = 0; i < max_retries; ++i) {
311 StringExtractorGDBRemote echo_response;
312 echo_packet_result =
313 WaitForPacketNoLock(packet&: echo_response, timeout, sync_on_timeout: false);
314 if (echo_packet_result == PacketResult::Success) {
315 ++successful_responses;
316 if (response_regex.Execute(string: echo_response.GetStringRef())) {
317 sync_success = true;
318 break;
319 } else if (successful_responses == 1) {
320 // We got something else back as the first successful
321 // response, it probably is the response to the packet we
322 // actually wanted, so copy it over if this is the first
323 // success and continue to try to get the qEcho response
324 packet = echo_response;
325 got_actual_response = true;
326 }
327 } else if (echo_packet_result == PacketResult::ErrorReplyTimeout)
328 continue; // Packet timed out, continue waiting for a response
329 else
330 break; // Something else went wrong getting the packet back, we
331 // failed and are done trying
332 }
333 }
334
335 // We weren't able to sync back up with the server, we must abort
336 // otherwise all responses might not be from the right packets...
337 if (sync_success) {
338 // We timed out, but were able to recover
339 if (got_actual_response) {
340 // We initially timed out, but we did get a response that came in
341 // before the successful reply to our qEcho packet, so lets say
342 // everything is fine...
343 return PacketResult::Success;
344 }
345 } else {
346 disconnected = true;
347 Disconnect();
348 }
349 } else {
350 timed_out = true;
351 }
352 break;
353 case eConnectionStatusSuccess:
354 // printf ("status = success but error = %s\n",
355 // error.AsCString("<invalid>"));
356 break;
357
358 case eConnectionStatusEndOfFile:
359 case eConnectionStatusNoConnection:
360 case eConnectionStatusLostConnection:
361 case eConnectionStatusError:
362 disconnected = true;
363 Disconnect();
364 break;
365 }
366 }
367 }
368 packet.Clear();
369 if (disconnected)
370 return PacketResult::ErrorDisconnected;
371 if (timed_out)
372 return PacketResult::ErrorReplyTimeout;
373 else
374 return PacketResult::ErrorReplyFailed;
375}
376
377bool GDBRemoteCommunication::DecompressPacket() {
378 Log *log = GetLog(mask: GDBRLog::Packets);
379
380 if (!CompressionIsEnabled())
381 return true;
382
383 size_t pkt_size = m_bytes.size();
384
385 // Smallest possible compressed packet is $N#00 - an uncompressed empty
386 // reply, most commonly indicating an unsupported packet. Anything less than
387 // 5 characters, it's definitely not a compressed packet.
388 if (pkt_size < 5)
389 return true;
390
391 if (m_bytes[0] != '$' && m_bytes[0] != '%')
392 return true;
393 if (m_bytes[1] != 'C' && m_bytes[1] != 'N')
394 return true;
395
396 size_t hash_mark_idx = m_bytes.find(c: '#');
397 if (hash_mark_idx == std::string::npos)
398 return true;
399 if (hash_mark_idx + 2 >= m_bytes.size())
400 return true;
401
402 if (!::isxdigit(m_bytes[hash_mark_idx + 1]) ||
403 !::isxdigit(m_bytes[hash_mark_idx + 2]))
404 return true;
405
406 size_t content_length =
407 pkt_size -
408 5; // not counting '$', 'C' | 'N', '#', & the two hex checksum chars
409 size_t content_start = 2; // The first character of the
410 // compressed/not-compressed text of the packet
411 size_t checksum_idx =
412 hash_mark_idx +
413 1; // The first character of the two hex checksum characters
414
415 // Normally size_of_first_packet == m_bytes.size() but m_bytes may contain
416 // multiple packets. size_of_first_packet is the size of the initial packet
417 // which we'll replace with the decompressed version of, leaving the rest of
418 // m_bytes unmodified.
419 size_t size_of_first_packet = hash_mark_idx + 3;
420
421 // Compressed packets ("$C") start with a base10 number which is the size of
422 // the uncompressed payload, then a : and then the compressed data. e.g.
423 // $C1024:<binary>#00 Update content_start and content_length to only include
424 // the <binary> part of the packet.
425
426 uint64_t decompressed_bufsize = ULONG_MAX;
427 if (m_bytes[1] == 'C') {
428 size_t i = content_start;
429 while (i < hash_mark_idx && isdigit(m_bytes[i]))
430 i++;
431 if (i < hash_mark_idx && m_bytes[i] == ':') {
432 i++;
433 content_start = i;
434 content_length = hash_mark_idx - content_start;
435 std::string bufsize_str(m_bytes.data() + 2, i - 2 - 1);
436 errno = 0;
437 decompressed_bufsize = ::strtoul(nptr: bufsize_str.c_str(), endptr: nullptr, base: 10);
438 if (errno != 0 || decompressed_bufsize == ULONG_MAX) {
439 m_bytes.erase(pos: 0, n: size_of_first_packet);
440 return false;
441 }
442 }
443 }
444
445 if (GetSendAcks()) {
446 char packet_checksum_cstr[3];
447 packet_checksum_cstr[0] = m_bytes[checksum_idx];
448 packet_checksum_cstr[1] = m_bytes[checksum_idx + 1];
449 packet_checksum_cstr[2] = '\0';
450 long packet_checksum = strtol(nptr: packet_checksum_cstr, endptr: nullptr, base: 16);
451
452 long actual_checksum = CalculcateChecksum(
453 payload: llvm::StringRef(m_bytes).substr(Start: 1, N: hash_mark_idx - 1));
454 bool success = packet_checksum == actual_checksum;
455 if (!success) {
456 LLDB_LOGF(log,
457 "error: checksum mismatch: %.*s expected 0x%2.2x, got 0x%2.2x",
458 (int)(pkt_size), m_bytes.c_str(), (uint8_t)packet_checksum,
459 (uint8_t)actual_checksum);
460 }
461 // Send the ack or nack if needed
462 if (!success) {
463 SendNack();
464 m_bytes.erase(pos: 0, n: size_of_first_packet);
465 return false;
466 } else {
467 SendAck();
468 }
469 }
470
471 if (m_bytes[1] == 'N') {
472 // This packet was not compressed -- delete the 'N' character at the start
473 // and the packet may be processed as-is.
474 m_bytes.erase(pos: 1, n: 1);
475 return true;
476 }
477
478 // Reverse the gdb-remote binary escaping that was done to the compressed
479 // text to guard characters like '$', '#', '}', etc.
480 std::vector<uint8_t> unescaped_content;
481 unescaped_content.reserve(n: content_length);
482 size_t i = content_start;
483 while (i < hash_mark_idx) {
484 if (m_bytes[i] == '}') {
485 i++;
486 unescaped_content.push_back(x: m_bytes[i] ^ 0x20);
487 } else {
488 unescaped_content.push_back(x: m_bytes[i]);
489 }
490 i++;
491 }
492
493 uint8_t *decompressed_buffer = nullptr;
494 size_t decompressed_bytes = 0;
495
496 if (decompressed_bufsize != ULONG_MAX) {
497 decompressed_buffer = (uint8_t *)malloc(size: decompressed_bufsize);
498 if (decompressed_buffer == nullptr) {
499 m_bytes.erase(pos: 0, n: size_of_first_packet);
500 return false;
501 }
502 }
503
504#if HAVE_LIBCOMPRESSION
505 if (m_compression_type == CompressionType::ZlibDeflate ||
506 m_compression_type == CompressionType::LZFSE ||
507 m_compression_type == CompressionType::LZ4 ||
508 m_compression_type == CompressionType::LZMA) {
509 compression_algorithm compression_type;
510 if (m_compression_type == CompressionType::LZFSE)
511 compression_type = COMPRESSION_LZFSE;
512 else if (m_compression_type == CompressionType::ZlibDeflate)
513 compression_type = COMPRESSION_ZLIB;
514 else if (m_compression_type == CompressionType::LZ4)
515 compression_type = COMPRESSION_LZ4_RAW;
516 else if (m_compression_type == CompressionType::LZMA)
517 compression_type = COMPRESSION_LZMA;
518
519 if (m_decompression_scratch_type != m_compression_type) {
520 if (m_decompression_scratch) {
521 free (m_decompression_scratch);
522 m_decompression_scratch = nullptr;
523 }
524 size_t scratchbuf_size = 0;
525 if (m_compression_type == CompressionType::LZFSE)
526 scratchbuf_size = compression_decode_scratch_buffer_size (COMPRESSION_LZFSE);
527 else if (m_compression_type == CompressionType::LZ4)
528 scratchbuf_size = compression_decode_scratch_buffer_size (COMPRESSION_LZ4_RAW);
529 else if (m_compression_type == CompressionType::ZlibDeflate)
530 scratchbuf_size = compression_decode_scratch_buffer_size (COMPRESSION_ZLIB);
531 else if (m_compression_type == CompressionType::LZMA)
532 scratchbuf_size =
533 compression_decode_scratch_buffer_size(COMPRESSION_LZMA);
534 if (scratchbuf_size > 0) {
535 m_decompression_scratch = (void*) malloc (scratchbuf_size);
536 m_decompression_scratch_type = m_compression_type;
537 }
538 }
539
540 if (decompressed_bufsize != ULONG_MAX && decompressed_buffer != nullptr) {
541 decompressed_bytes = compression_decode_buffer(
542 decompressed_buffer, decompressed_bufsize,
543 (uint8_t *)unescaped_content.data(), unescaped_content.size(),
544 m_decompression_scratch, compression_type);
545 }
546 }
547#endif
548
549#if LLVM_ENABLE_ZLIB
550 if (decompressed_bytes == 0 && decompressed_bufsize != ULONG_MAX &&
551 decompressed_buffer != nullptr &&
552 m_compression_type == CompressionType::ZlibDeflate) {
553 z_stream stream;
554 memset(s: &stream, c: 0, n: sizeof(z_stream));
555 stream.next_in = (Bytef *)unescaped_content.data();
556 stream.avail_in = (uInt)unescaped_content.size();
557 stream.total_in = 0;
558 stream.next_out = (Bytef *)decompressed_buffer;
559 stream.avail_out = decompressed_bufsize;
560 stream.total_out = 0;
561 stream.zalloc = Z_NULL;
562 stream.zfree = Z_NULL;
563 stream.opaque = Z_NULL;
564
565 if (inflateInit2(&stream, -15) == Z_OK) {
566 int status = inflate(strm: &stream, Z_NO_FLUSH);
567 inflateEnd(strm: &stream);
568 if (status == Z_STREAM_END) {
569 decompressed_bytes = stream.total_out;
570 }
571 }
572 }
573#endif
574
575 if (decompressed_bytes == 0 || decompressed_buffer == nullptr) {
576 if (decompressed_buffer)
577 free(ptr: decompressed_buffer);
578 m_bytes.erase(pos: 0, n: size_of_first_packet);
579 return false;
580 }
581
582 std::string new_packet;
583 new_packet.reserve(res_arg: decompressed_bytes + 6);
584 new_packet.push_back(c: m_bytes[0]);
585 new_packet.append(s: (const char *)decompressed_buffer, n: decompressed_bytes);
586 new_packet.push_back(c: '#');
587 if (GetSendAcks()) {
588 uint8_t decompressed_checksum = CalculcateChecksum(
589 payload: llvm::StringRef((const char *)decompressed_buffer, decompressed_bytes));
590 char decompressed_checksum_str[3];
591 snprintf(s: decompressed_checksum_str, maxlen: 3, format: "%02x", decompressed_checksum);
592 new_packet.append(s: decompressed_checksum_str);
593 } else {
594 new_packet.push_back(c: '0');
595 new_packet.push_back(c: '0');
596 }
597
598 m_bytes.replace(pos: 0, n1: size_of_first_packet, s: new_packet.data(),
599 n2: new_packet.size());
600
601 free(ptr: decompressed_buffer);
602 return true;
603}
604
605GDBRemoteCommunication::PacketType
606GDBRemoteCommunication::CheckForPacket(const uint8_t *src, size_t src_len,
607 StringExtractorGDBRemote &packet) {
608 // Put the packet data into the buffer in a thread safe fashion
609 std::lock_guard<std::recursive_mutex> guard(m_bytes_mutex);
610
611 Log *log = GetLog(mask: GDBRLog::Packets);
612
613 if (src && src_len > 0) {
614 if (log && log->GetVerbose()) {
615 StreamString s;
616 LLDB_LOGF(log, "GDBRemoteCommunication::%s adding %u bytes: %.*s",
617 __FUNCTION__, (uint32_t)src_len, (uint32_t)src_len, src);
618 }
619 m_bytes.append(s: (const char *)src, n: src_len);
620 }
621
622 bool isNotifyPacket = false;
623
624 // Parse up the packets into gdb remote packets
625 if (!m_bytes.empty()) {
626 // end_idx must be one past the last valid packet byte. Start it off with
627 // an invalid value that is the same as the current index.
628 size_t content_start = 0;
629 size_t content_length = 0;
630 size_t total_length = 0;
631 size_t checksum_idx = std::string::npos;
632
633 // Size of packet before it is decompressed, for logging purposes
634 size_t original_packet_size = m_bytes.size();
635 if (CompressionIsEnabled()) {
636 if (!DecompressPacket()) {
637 packet.Clear();
638 return GDBRemoteCommunication::PacketType::Standard;
639 }
640 }
641
642 switch (m_bytes[0]) {
643 case '+': // Look for ack
644 case '-': // Look for cancel
645 case '\x03': // ^C to halt target
646 content_length = total_length = 1; // The command is one byte long...
647 break;
648
649 case '%': // Async notify packet
650 isNotifyPacket = true;
651 [[fallthrough]];
652
653 case '$':
654 // Look for a standard gdb packet?
655 {
656 size_t hash_pos = m_bytes.find(c: '#');
657 if (hash_pos != std::string::npos) {
658 if (hash_pos + 2 < m_bytes.size()) {
659 checksum_idx = hash_pos + 1;
660 // Skip the dollar sign
661 content_start = 1;
662 // Don't include the # in the content or the $ in the content
663 // length
664 content_length = hash_pos - 1;
665
666 total_length =
667 hash_pos + 3; // Skip the # and the two hex checksum bytes
668 } else {
669 // Checksum bytes aren't all here yet
670 content_length = std::string::npos;
671 }
672 }
673 }
674 break;
675
676 default: {
677 // We have an unexpected byte and we need to flush all bad data that is
678 // in m_bytes, so we need to find the first byte that is a '+' (ACK), '-'
679 // (NACK), \x03 (CTRL+C interrupt), or '$' character (start of packet
680 // header) or of course, the end of the data in m_bytes...
681 const size_t bytes_len = m_bytes.size();
682 bool done = false;
683 uint32_t idx;
684 for (idx = 1; !done && idx < bytes_len; ++idx) {
685 switch (m_bytes[idx]) {
686 case '+':
687 case '-':
688 case '\x03':
689 case '%':
690 case '$':
691 done = true;
692 break;
693
694 default:
695 break;
696 }
697 }
698 LLDB_LOGF(log, "GDBRemoteCommunication::%s tossing %u junk bytes: '%.*s'",
699 __FUNCTION__, idx - 1, idx - 1, m_bytes.c_str());
700 m_bytes.erase(pos: 0, n: idx - 1);
701 } break;
702 }
703
704 if (content_length == std::string::npos) {
705 packet.Clear();
706 return GDBRemoteCommunication::PacketType::Invalid;
707 } else if (total_length > 0) {
708
709 // We have a valid packet...
710 assert(content_length <= m_bytes.size());
711 assert(total_length <= m_bytes.size());
712 assert(content_length <= total_length);
713 size_t content_end = content_start + content_length;
714
715 bool success = true;
716 if (log) {
717 // If logging was just enabled and we have history, then dump out what
718 // we have to the log so we get the historical context. The Dump() call
719 // that logs all of the packet will set a boolean so that we don't dump
720 // this more than once
721 if (!m_history.DidDumpToLog())
722 m_history.Dump(log);
723
724 bool binary = false;
725 // Only detect binary for packets that start with a '$' and have a
726 // '#CC' checksum
727 if (m_bytes[0] == '$' && total_length > 4) {
728 for (size_t i = 0; !binary && i < total_length; ++i) {
729 unsigned char c = m_bytes[i];
730 if (!llvm::isPrint(C: c) && !llvm::isSpace(C: c)) {
731 binary = true;
732 }
733 }
734 }
735 if (binary) {
736 StreamString strm;
737 // Packet header...
738 if (CompressionIsEnabled())
739 strm.Printf(format: "<%4" PRIu64 ":%" PRIu64 "> read packet: %c",
740 (uint64_t)original_packet_size, (uint64_t)total_length,
741 m_bytes[0]);
742 else
743 strm.Printf(format: "<%4" PRIu64 "> read packet: %c",
744 (uint64_t)total_length, m_bytes[0]);
745 for (size_t i = content_start; i < content_end; ++i) {
746 // Remove binary escaped bytes when displaying the packet...
747 const char ch = m_bytes[i];
748 if (ch == 0x7d) {
749 // 0x7d is the escape character. The next character is to be
750 // XOR'd with 0x20.
751 const char escapee = m_bytes[++i] ^ 0x20;
752 strm.Printf(format: "%2.2x", escapee);
753 } else {
754 strm.Printf(format: "%2.2x", (uint8_t)ch);
755 }
756 }
757 // Packet footer...
758 strm.Printf(format: "%c%c%c", m_bytes[total_length - 3],
759 m_bytes[total_length - 2], m_bytes[total_length - 1]);
760 log->PutString(str: strm.GetString());
761 } else {
762 if (CompressionIsEnabled())
763 LLDB_LOGF(log, "<%4" PRIu64 ":%" PRIu64 "> read packet: %.*s",
764 (uint64_t)original_packet_size, (uint64_t)total_length,
765 (int)(total_length), m_bytes.c_str());
766 else
767 LLDB_LOGF(log, "<%4" PRIu64 "> read packet: %.*s",
768 (uint64_t)total_length, (int)(total_length),
769 m_bytes.c_str());
770 }
771 }
772
773 m_history.AddPacket(src: m_bytes, src_len: total_length,
774 type: GDBRemotePacket::ePacketTypeRecv, bytes_transmitted: total_length);
775
776 // Copy the packet from m_bytes to packet_str expanding the run-length
777 // encoding in the process.
778 auto maybe_packet_str =
779 ExpandRLE(m_bytes.substr(pos: content_start, n: content_end - content_start));
780 if (!maybe_packet_str) {
781 m_bytes.erase(pos: 0, n: total_length);
782 packet.Clear();
783 return GDBRemoteCommunication::PacketType::Invalid;
784 }
785 packet = StringExtractorGDBRemote(*maybe_packet_str);
786
787 if (m_bytes[0] == '$' || m_bytes[0] == '%') {
788 assert(checksum_idx < m_bytes.size());
789 if (::isxdigit(m_bytes[checksum_idx + 0]) ||
790 ::isxdigit(m_bytes[checksum_idx + 1])) {
791 if (GetSendAcks()) {
792 const char *packet_checksum_cstr = &m_bytes[checksum_idx];
793 char packet_checksum = strtol(nptr: packet_checksum_cstr, endptr: nullptr, base: 16);
794 char actual_checksum = CalculcateChecksum(
795 payload: llvm::StringRef(m_bytes).slice(Start: content_start, End: content_end));
796 success = packet_checksum == actual_checksum;
797 if (!success) {
798 LLDB_LOGF(log,
799 "error: checksum mismatch: %.*s expected 0x%2.2x, "
800 "got 0x%2.2x",
801 (int)(total_length), m_bytes.c_str(),
802 (uint8_t)packet_checksum, (uint8_t)actual_checksum);
803 }
804 // Send the ack or nack if needed
805 if (!success)
806 SendNack();
807 else
808 SendAck();
809 }
810 } else {
811 success = false;
812 LLDB_LOGF(log, "error: invalid checksum in packet: '%s'\n",
813 m_bytes.c_str());
814 }
815 }
816
817 m_bytes.erase(pos: 0, n: total_length);
818 packet.SetFilePos(0);
819
820 if (isNotifyPacket)
821 return GDBRemoteCommunication::PacketType::Notify;
822 else
823 return GDBRemoteCommunication::PacketType::Standard;
824 }
825 }
826 packet.Clear();
827 return GDBRemoteCommunication::PacketType::Invalid;
828}
829
830Status GDBRemoteCommunication::StartDebugserverProcess(
831 std::variant<llvm::StringRef, shared_fd_t> comm,
832 ProcessLaunchInfo &launch_info, const Args *inferior_args) {
833 Log *log = GetLog(mask: GDBRLog::Process);
834
835 Args &debugserver_args = launch_info.GetArguments();
836
837#if !defined(__APPLE__)
838 // First argument to lldb-server must be mode in which to run.
839 debugserver_args.AppendArgument(arg_str: "gdbserver");
840#endif
841
842 // use native registers, not the GDB registers
843 debugserver_args.AppendArgument(arg_str: "--native-regs");
844
845 if (launch_info.GetLaunchInSeparateProcessGroup())
846 debugserver_args.AppendArgument(arg_str: "--setsid");
847
848 llvm::SmallString<128> named_pipe_path;
849 // socket_pipe is used by debug server to communicate back either
850 // TCP port or domain socket name which it listens on. However, we're not
851 // interested in the actualy value here.
852 // The only reason for using the pipe is to serve as a synchronization point -
853 // once data is written to the pipe, debug server is up and running.
854 Pipe socket_pipe;
855
856 // If a url is supplied then use it
857 if (shared_fd_t *comm_fd = std::get_if<shared_fd_t>(ptr: &comm)) {
858 LLDB_LOG(log, "debugserver communicates over fd {0}", comm_fd);
859 assert(*comm_fd != SharedSocket::kInvalidFD);
860 debugserver_args.AppendArgument(arg_str: llvm::formatv(Fmt: "--fd={0}", Vals&: *comm_fd).str());
861 // Send "comm_fd" down to the inferior so it can use it to communicate back
862 // with this process.
863 launch_info.AppendDuplicateFileAction(fd: (int64_t)*comm_fd, dup_fd: (int64_t)*comm_fd);
864 } else {
865 llvm::StringRef url = std::get<llvm::StringRef>(v&: comm);
866 LLDB_LOG(log, "debugserver listens on: {0}", url);
867 debugserver_args.AppendArgument(arg_str: url);
868
869#if defined(__APPLE__)
870 // Using a named pipe as debugserver does not support --pipe.
871 Status error = socket_pipe.CreateWithUniqueName("debugserver-named-pipe",
872 named_pipe_path);
873 if (error.Fail()) {
874 LLDB_LOG(log, "named pipe creation failed: {0}", error);
875 return error;
876 }
877 debugserver_args.AppendArgument(llvm::StringRef("--named-pipe"));
878 debugserver_args.AppendArgument(named_pipe_path);
879#else
880 // Using an unnamed pipe as it's simpler.
881 Status error = socket_pipe.CreateNew();
882 if (error.Fail()) {
883 LLDB_LOG(log, "unnamed pipe creation failed: {0}", error);
884 return error;
885 }
886 pipe_t write = socket_pipe.GetWritePipe();
887 debugserver_args.AppendArgument(arg_str: llvm::StringRef("--pipe"));
888 debugserver_args.AppendArgument(arg_str: llvm::to_string(Value: write));
889 launch_info.AppendDuplicateFileAction(fd: (int64_t)write, dup_fd: (int64_t)write);
890#endif
891 }
892
893 Environment host_env = Host::GetEnvironment();
894 std::string env_debugserver_log_file =
895 host_env.lookup(Key: "LLDB_DEBUGSERVER_LOG_FILE");
896 if (!env_debugserver_log_file.empty()) {
897 debugserver_args.AppendArgument(
898 arg_str: llvm::formatv(Fmt: "--log-file={0}", Vals&: env_debugserver_log_file).str());
899 }
900
901#if defined(__APPLE__)
902 const char *env_debugserver_log_flags = getenv("LLDB_DEBUGSERVER_LOG_FLAGS");
903 if (env_debugserver_log_flags) {
904 debugserver_args.AppendArgument(
905 llvm::formatv("--log-flags={0}", env_debugserver_log_flags).str());
906 }
907#else
908 std::string env_debugserver_log_channels =
909 host_env.lookup(Key: "LLDB_SERVER_LOG_CHANNELS");
910 if (!env_debugserver_log_channels.empty()) {
911 debugserver_args.AppendArgument(
912 arg_str: llvm::formatv(Fmt: "--log-channels={0}", Vals&: env_debugserver_log_channels)
913 .str());
914 }
915#endif
916
917 // Add additional args, starting with LLDB_DEBUGSERVER_EXTRA_ARG_1 until an
918 // env var doesn't come back.
919 uint32_t env_var_index = 1;
920 bool has_env_var;
921 do {
922 char env_var_name[64];
923 snprintf(s: env_var_name, maxlen: sizeof(env_var_name),
924 format: "LLDB_DEBUGSERVER_EXTRA_ARG_%" PRIu32, env_var_index++);
925 std::string extra_arg = host_env.lookup(Key: env_var_name);
926 has_env_var = !extra_arg.empty();
927
928 if (has_env_var) {
929 debugserver_args.AppendArgument(arg_str: llvm::StringRef(extra_arg));
930 LLDB_LOGF(log,
931 "GDBRemoteCommunication::%s adding env var %s contents "
932 "to stub command line (%s)",
933 __FUNCTION__, env_var_name, extra_arg.c_str());
934 }
935 } while (has_env_var);
936
937 if (inferior_args && inferior_args->GetArgumentCount() > 0) {
938 debugserver_args.AppendArgument(arg_str: llvm::StringRef("--"));
939 debugserver_args.AppendArguments(rhs: *inferior_args);
940 }
941
942 // Copy the current environment to the gdbserver/debugserver instance
943 launch_info.GetEnvironment() = host_env;
944
945 // Close STDIN, STDOUT and STDERR.
946 launch_info.AppendCloseFileAction(STDIN_FILENO);
947 launch_info.AppendCloseFileAction(STDOUT_FILENO);
948 launch_info.AppendCloseFileAction(STDERR_FILENO);
949
950 // Redirect STDIN, STDOUT and STDERR to "/dev/null".
951 launch_info.AppendSuppressFileAction(STDIN_FILENO, read: true, write: false);
952 launch_info.AppendSuppressFileAction(STDOUT_FILENO, read: false, write: true);
953 launch_info.AppendSuppressFileAction(STDERR_FILENO, read: false, write: true);
954
955 if (log) {
956 StreamString string_stream;
957 Platform *const platform = nullptr;
958 launch_info.Dump(s&: string_stream, platform);
959 LLDB_LOG(log, "launch info for gdb-remote stub:\n{0}",
960 string_stream.GetData());
961 }
962 if (Status error = Host::LaunchProcess(launch_info); error.Fail()) {
963 LLDB_LOG(log, "launch failed: {0}", error);
964 return error;
965 }
966
967 if (std::holds_alternative<shared_fd_t>(v: comm))
968 return Status();
969
970 Status error;
971 if (named_pipe_path.size() > 0) {
972 error = socket_pipe.OpenAsReader(name: named_pipe_path);
973 if (error.Fail()) {
974 LLDB_LOG(log, "failed to open named pipe {0} for reading: {1}",
975 named_pipe_path, error);
976 }
977 }
978
979 if (socket_pipe.CanWrite())
980 socket_pipe.CloseWriteFileDescriptor();
981 assert(socket_pipe.CanRead());
982
983 // Read data from the pipe -- and ignore it (see comment above).
984 while (error.Success()) {
985 char buf[10];
986 if (llvm::Expected<size_t> num_bytes =
987 socket_pipe.Read(buf, size: std::size(buf), timeout: std::chrono::seconds(10))) {
988 if (*num_bytes == 0)
989 break;
990 } else {
991 error = Status::FromError(error: num_bytes.takeError());
992 }
993 }
994 if (error.Fail()) {
995 LLDB_LOG(log, "failed to synchronize on pipe {0}: {1}", named_pipe_path,
996 error);
997 }
998 socket_pipe.Close();
999
1000 if (named_pipe_path.size() > 0) {
1001 if (Status err = socket_pipe.Delete(name: named_pipe_path); err.Fail())
1002 LLDB_LOG(log, "failed to delete pipe {0}: {1}", named_pipe_path, err);
1003 }
1004
1005 return error;
1006}
1007
1008void GDBRemoteCommunication::DumpHistory(Stream &strm) { m_history.Dump(strm); }
1009
1010GDBRemoteCommunication::ScopedTimeout::ScopedTimeout(
1011 GDBRemoteCommunication &gdb_comm, std::chrono::seconds timeout)
1012 : m_gdb_comm(gdb_comm), m_saved_timeout(0), m_timeout_modified(false) {
1013 auto curr_timeout = gdb_comm.GetPacketTimeout();
1014 // Only update the timeout if the timeout is greater than the current
1015 // timeout. If the current timeout is larger, then just use that.
1016 if (curr_timeout < timeout) {
1017 m_timeout_modified = true;
1018 m_saved_timeout = m_gdb_comm.SetPacketTimeout(timeout);
1019 }
1020}
1021
1022GDBRemoteCommunication::ScopedTimeout::~ScopedTimeout() {
1023 // Only restore the timeout if we set it in the constructor.
1024 if (m_timeout_modified)
1025 m_gdb_comm.SetPacketTimeout(m_saved_timeout);
1026}
1027
1028void llvm::format_provider<GDBRemoteCommunication::PacketResult>::format(
1029 const GDBRemoteCommunication::PacketResult &result, raw_ostream &Stream,
1030 StringRef Style) {
1031 using PacketResult = GDBRemoteCommunication::PacketResult;
1032
1033 switch (result) {
1034 case PacketResult::Success:
1035 Stream << "Success";
1036 break;
1037 case PacketResult::ErrorSendFailed:
1038 Stream << "ErrorSendFailed";
1039 break;
1040 case PacketResult::ErrorSendAck:
1041 Stream << "ErrorSendAck";
1042 break;
1043 case PacketResult::ErrorReplyFailed:
1044 Stream << "ErrorReplyFailed";
1045 break;
1046 case PacketResult::ErrorReplyTimeout:
1047 Stream << "ErrorReplyTimeout";
1048 break;
1049 case PacketResult::ErrorReplyInvalid:
1050 Stream << "ErrorReplyInvalid";
1051 break;
1052 case PacketResult::ErrorReplyAck:
1053 Stream << "ErrorReplyAck";
1054 break;
1055 case PacketResult::ErrorDisconnected:
1056 Stream << "ErrorDisconnected";
1057 break;
1058 case PacketResult::ErrorNoSequenceLock:
1059 Stream << "ErrorNoSequenceLock";
1060 break;
1061 }
1062}
1063
1064std::optional<std::string>
1065GDBRemoteCommunication::ExpandRLE(std::string packet) {
1066 // Reserve enough byte for the most common case (no RLE used).
1067 std::string decoded;
1068 decoded.reserve(res_arg: packet.size());
1069 for (std::string::const_iterator c = packet.begin(); c != packet.end(); ++c) {
1070 if (*c == '*') {
1071 if (decoded.empty())
1072 return std::nullopt;
1073 // '*' indicates RLE. Next character will give us the repeat count and
1074 // previous character is what is to be repeated.
1075 char char_to_repeat = decoded.back();
1076 // Number of time the previous character is repeated.
1077 if (++c == packet.end())
1078 return std::nullopt;
1079 int repeat_count = *c + 3 - ' ';
1080 // We have the char_to_repeat and repeat_count. Now push it in the
1081 // packet.
1082 for (int i = 0; i < repeat_count; ++i)
1083 decoded.push_back(c: char_to_repeat);
1084 } else if (*c == 0x7d) {
1085 // 0x7d is the escape character. The next character is to be XOR'd with
1086 // 0x20.
1087 if (++c == packet.end())
1088 return std::nullopt;
1089 char escapee = *c ^ 0x20;
1090 decoded.push_back(c: escapee);
1091 } else {
1092 decoded.push_back(c: *c);
1093 }
1094 }
1095 return decoded;
1096}
1097

source code of lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp