1//===-- llvm/Support/raw_socket_stream.cpp - Socket streams --*- C++ -*-===//
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// This file contains raw_ostream implementations for streams to communicate
10// via UNIX sockets
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Support/raw_socket_stream.h"
15#include "llvm/Config/config.h"
16#include "llvm/Support/Error.h"
17#include "llvm/Support/FileSystem.h"
18
19#include <atomic>
20#include <fcntl.h>
21#include <functional>
22#include <thread>
23
24#ifndef _WIN32
25#include <poll.h>
26#include <sys/socket.h>
27#include <sys/un.h>
28#else
29#include "llvm/Support/Windows/WindowsSupport.h"
30// winsock2.h must be included before afunix.h. Briefly turn off clang-format to
31// avoid error.
32// clang-format off
33#include <winsock2.h>
34#include <afunix.h>
35// clang-format on
36#include <io.h>
37#endif // _WIN32
38
39#if defined(HAVE_UNISTD_H)
40#include <unistd.h>
41#endif
42
43using namespace llvm;
44
45#ifdef _WIN32
46WSABalancer::WSABalancer() {
47 WSADATA WsaData;
48 ::memset(&WsaData, 0, sizeof(WsaData));
49 if (WSAStartup(MAKEWORD(2, 2), &WsaData) != 0) {
50 llvm::report_fatal_error("WSAStartup failed");
51 }
52}
53
54WSABalancer::~WSABalancer() { WSACleanup(); }
55#endif // _WIN32
56
57static std::error_code getLastSocketErrorCode() {
58#ifdef _WIN32
59 return std::error_code(::WSAGetLastError(), std::system_category());
60#else
61 return errnoAsErrorCode();
62#endif
63}
64
65static sockaddr_un setSocketAddr(StringRef SocketPath) {
66 struct sockaddr_un Addr;
67 memset(s: &Addr, c: 0, n: sizeof(Addr));
68 Addr.sun_family = AF_UNIX;
69 strncpy(dest: Addr.sun_path, src: SocketPath.str().c_str(), n: sizeof(Addr.sun_path) - 1);
70 return Addr;
71}
72
73static Expected<int> getSocketFD(StringRef SocketPath) {
74#ifdef _WIN32
75 SOCKET Socket = socket(AF_UNIX, SOCK_STREAM, 0);
76 if (Socket == INVALID_SOCKET) {
77#else
78 int Socket = socket(AF_UNIX, SOCK_STREAM, protocol: 0);
79 if (Socket == -1) {
80#endif // _WIN32
81 return llvm::make_error<StringError>(Args: getLastSocketErrorCode(),
82 Args: "Create socket failed");
83 }
84
85 struct sockaddr_un Addr = setSocketAddr(SocketPath);
86 if (::connect(fd: Socket, addr: (struct sockaddr *)&Addr, len: sizeof(Addr)) == -1)
87 return llvm::make_error<StringError>(Args: getLastSocketErrorCode(),
88 Args: "Connect socket failed");
89
90#ifdef _WIN32
91 return _open_osfhandle(Socket, 0);
92#else
93 return Socket;
94#endif // _WIN32
95}
96
97ListeningSocket::ListeningSocket(int SocketFD, StringRef SocketPath,
98 int PipeFD[2])
99 : FD(SocketFD), SocketPath(SocketPath), PipeFD{PipeFD[0], PipeFD[1]} {}
100
101ListeningSocket::ListeningSocket(ListeningSocket &&LS)
102 : FD(LS.FD.load()), SocketPath(LS.SocketPath),
103 PipeFD{LS.PipeFD[0], LS.PipeFD[1]} {
104
105 LS.FD = -1;
106 LS.SocketPath.clear();
107 LS.PipeFD[0] = -1;
108 LS.PipeFD[1] = -1;
109}
110
111Expected<ListeningSocket> ListeningSocket::createUnix(StringRef SocketPath,
112 int MaxBacklog) {
113
114 // Handle instances where the target socket address already exists and
115 // differentiate between a preexisting file with and without a bound socket
116 //
117 // ::bind will return std::errc:address_in_use if a file at the socket address
118 // already exists (e.g., the file was not properly unlinked due to a crash)
119 // even if another socket has not yet binded to that address
120 if (llvm::sys::fs::exists(Path: SocketPath)) {
121 Expected<int> MaybeFD = getSocketFD(SocketPath);
122 if (!MaybeFD) {
123
124 // Regardless of the error, notify the caller that a file already exists
125 // at the desired socket address and that there is no bound socket at that
126 // address. The file must be removed before ::bind can use the address
127 consumeError(Err: MaybeFD.takeError());
128 return llvm::make_error<StringError>(
129 Args: std::make_error_code(e: std::errc::file_exists),
130 Args: "Socket address unavailable");
131 }
132 ::close(fd: std::move(*MaybeFD));
133
134 // Notify caller that the provided socket address already has a bound socket
135 return llvm::make_error<StringError>(
136 Args: std::make_error_code(e: std::errc::address_in_use),
137 Args: "Socket address unavailable");
138 }
139
140#ifdef _WIN32
141 WSABalancer _;
142 SOCKET Socket = socket(AF_UNIX, SOCK_STREAM, 0);
143 if (Socket == INVALID_SOCKET)
144#else
145 int Socket = socket(AF_UNIX, SOCK_STREAM, protocol: 0);
146 if (Socket == -1)
147#endif
148 return llvm::make_error<StringError>(Args: getLastSocketErrorCode(),
149 Args: "socket create failed");
150
151 struct sockaddr_un Addr = setSocketAddr(SocketPath);
152 if (::bind(fd: Socket, addr: (struct sockaddr *)&Addr, len: sizeof(Addr)) == -1) {
153 // Grab error code from call to ::bind before calling ::close
154 std::error_code EC = getLastSocketErrorCode();
155 ::close(fd: Socket);
156 return llvm::make_error<StringError>(Args&: EC, Args: "Bind error");
157 }
158
159 // Mark socket as passive so incoming connections can be accepted
160 if (::listen(fd: Socket, n: MaxBacklog) == -1)
161 return llvm::make_error<StringError>(Args: getLastSocketErrorCode(),
162 Args: "Listen error");
163
164 int PipeFD[2];
165#ifdef _WIN32
166 // Reserve 1 byte for the pipe and use default textmode
167 if (::_pipe(PipeFD, 1, 0) == -1)
168#else
169 if (::pipe(pipedes: PipeFD) == -1)
170#endif // _WIN32
171 return llvm::make_error<StringError>(Args: getLastSocketErrorCode(),
172 Args: "pipe failed");
173
174#ifdef _WIN32
175 return ListeningSocket{_open_osfhandle(Socket, 0), SocketPath, PipeFD};
176#else
177 return ListeningSocket{Socket, SocketPath, PipeFD};
178#endif // _WIN32
179}
180
181// If a file descriptor being monitored by ::poll is closed by another thread,
182// the result is unspecified. In the case ::poll does not unblock and return,
183// when ActiveFD is closed, you can provide another file descriptor via CancelFD
184// that when written to will cause poll to return. Typically CancelFD is the
185// read end of a unidirectional pipe.
186//
187// Timeout should be -1 to block indefinitly
188//
189// getActiveFD is a callback to handle ActiveFD's of std::atomic<int> and int
190static std::error_code
191manageTimeout(const std::chrono::milliseconds &Timeout,
192 const std::function<int()> &getActiveFD,
193 const std::optional<int> &CancelFD = std::nullopt) {
194 struct pollfd FD[2];
195 FD[0].events = POLLIN;
196#ifdef _WIN32
197 SOCKET WinServerSock = _get_osfhandle(getActiveFD());
198 FD[0].fd = WinServerSock;
199#else
200 FD[0].fd = getActiveFD();
201#endif
202 uint8_t FDCount = 1;
203 if (CancelFD.has_value()) {
204 FD[1].events = POLLIN;
205 FD[1].fd = CancelFD.value();
206 FDCount++;
207 }
208
209 // Keep track of how much time has passed in case ::poll or WSAPoll are
210 // interupted by a signal and need to be recalled
211 auto Start = std::chrono::steady_clock::now();
212 auto RemainingTimeout = Timeout;
213 int PollStatus = 0;
214 do {
215 // If Timeout is -1 then poll should block and RemainingTimeout does not
216 // need to be recalculated
217 if (PollStatus != 0 && Timeout != std::chrono::milliseconds(-1)) {
218 auto TotalElapsedTime =
219 std::chrono::duration_cast<std::chrono::milliseconds>(
220 d: std::chrono::steady_clock::now() - Start);
221
222 if (TotalElapsedTime >= Timeout)
223 return std::make_error_code(e: std::errc::operation_would_block);
224
225 RemainingTimeout = Timeout - TotalElapsedTime;
226 }
227#ifdef _WIN32
228 PollStatus = WSAPoll(FD, FDCount, RemainingTimeout.count());
229 } while (PollStatus == SOCKET_ERROR &&
230 getLastSocketErrorCode() == std::errc::interrupted);
231#else
232 PollStatus = ::poll(fds: FD, nfds: FDCount, timeout: RemainingTimeout.count());
233 } while (PollStatus == -1 &&
234 getLastSocketErrorCode() == std::errc::interrupted);
235#endif
236
237 // If ActiveFD equals -1 or CancelFD has data to be read then the operation
238 // has been canceled by another thread
239 if (getActiveFD() == -1 || (CancelFD.has_value() && FD[1].revents & POLLIN))
240 return std::make_error_code(e: std::errc::operation_canceled);
241#if _WIN32
242 if (PollStatus == SOCKET_ERROR)
243#else
244 if (PollStatus == -1)
245#endif
246 return getLastSocketErrorCode();
247 if (PollStatus == 0)
248 return std::make_error_code(e: std::errc::timed_out);
249 if (FD[0].revents & POLLNVAL)
250 return std::make_error_code(e: std::errc::bad_file_descriptor);
251 return std::error_code();
252}
253
254Expected<std::unique_ptr<raw_socket_stream>>
255ListeningSocket::accept(const std::chrono::milliseconds &Timeout) {
256 auto getActiveFD = [this]() -> int { return FD; };
257 std::error_code TimeoutErr = manageTimeout(Timeout, getActiveFD, CancelFD: PipeFD[0]);
258 if (TimeoutErr)
259 return llvm::make_error<StringError>(Args&: TimeoutErr, Args: "Timeout error");
260
261 int AcceptFD;
262#ifdef _WIN32
263 SOCKET WinAcceptSock = ::accept(_get_osfhandle(FD), NULL, NULL);
264 AcceptFD = _open_osfhandle(WinAcceptSock, 0);
265#else
266 AcceptFD = ::accept(fd: FD, NULL, NULL);
267#endif
268
269 if (AcceptFD == -1)
270 return llvm::make_error<StringError>(Args: getLastSocketErrorCode(),
271 Args: "Socket accept failed");
272 return std::make_unique<raw_socket_stream>(args&: AcceptFD);
273}
274
275void ListeningSocket::shutdown() {
276 int ObservedFD = FD.load();
277
278 if (ObservedFD == -1)
279 return;
280
281 // If FD equals ObservedFD set FD to -1; If FD doesn't equal ObservedFD then
282 // another thread is responsible for shutdown so return
283 if (!FD.compare_exchange_strong(i1&: ObservedFD, i2: -1))
284 return;
285
286 ::close(fd: ObservedFD);
287 ::unlink(name: SocketPath.c_str());
288
289 // Ensure ::poll returns if shutdown is called by a separate thread
290 char Byte = 'A';
291 ssize_t written = ::write(fd: PipeFD[1], buf: &Byte, n: 1);
292
293 // Ignore any write() error
294 (void)written;
295}
296
297ListeningSocket::~ListeningSocket() {
298 shutdown();
299
300 // Close the pipe's FDs in the destructor instead of within
301 // ListeningSocket::shutdown to avoid unnecessary synchronization issues that
302 // would occur as PipeFD's values would have to be changed to -1
303 //
304 // The move constructor sets PipeFD to -1
305 if (PipeFD[0] != -1)
306 ::close(fd: PipeFD[0]);
307 if (PipeFD[1] != -1)
308 ::close(fd: PipeFD[1]);
309}
310
311//===----------------------------------------------------------------------===//
312// raw_socket_stream
313//===----------------------------------------------------------------------===//
314
315raw_socket_stream::raw_socket_stream(int SocketFD)
316 : raw_fd_stream(SocketFD, true) {}
317
318raw_socket_stream::~raw_socket_stream() {}
319
320Expected<std::unique_ptr<raw_socket_stream>>
321raw_socket_stream::createConnectedUnix(StringRef SocketPath) {
322#ifdef _WIN32
323 WSABalancer _;
324#endif // _WIN32
325 Expected<int> FD = getSocketFD(SocketPath);
326 if (!FD)
327 return FD.takeError();
328 return std::make_unique<raw_socket_stream>(args&: *FD);
329}
330
331ssize_t raw_socket_stream::read(char *Ptr, size_t Size,
332 const std::chrono::milliseconds &Timeout) {
333 auto getActiveFD = [this]() -> int { return this->get_fd(); };
334 std::error_code Err = manageTimeout(Timeout, getActiveFD);
335 // Mimic raw_fd_stream::read error handling behavior
336 if (Err) {
337 raw_fd_stream::error_detected(EC: Err);
338 return -1;
339 }
340 return raw_fd_stream::read(Ptr, Size);
341}
342