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collabora-online/net/FakeSocket.cpp

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
/*
* Copyright the Collabora Online contributors.
*
* SPDX-License-Identifier: MPL-2.0
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <cassert>
#include <chrono>
#include <condition_variable>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <sstream>
#include <mutex>
#include <thread>
#include <vector>
// A "fake socket" is represented by a number, a smallish integer, just like a real socket.
//
// There is one FakeSocketPair for each two sequential fake socket numbers. When you create one, you
// will always get the lower (even) number in a pair. The higher number will be returned if you
// successfully call fakeSocketConnect() from the lower number to some other fake socket.
//
// After you create a fake socket, there is basically just two things you can do with it:
//
// 1) Call fakeSocketConnect on it giving another fake socket number to connect to. Once the
// connection is successful, you can call fakeSocketRead() and fakeSocketWrite() on your original
// socket.
//
// 2) Call fakeSocketListen() on it, indicating it is a "server" socket. After that, keep calling
// fakeSocketAccept() and each time that returns successfully, it will return a new fake socket that
// is connected to another fake socket that called fakeSocketConnect() to the server socket. You can
// then call fakeSocketRead() and fakeSocketWrite() on it.
//
// This all is complicated a bit by the fact that all the API is non-blocking.
struct FakeSocketPair
{
int fd[2];
bool listening;
int connectingFd;
bool shutdown[2];
bool readable[2];
std::vector<std::vector<char>> buffer[2];
FakeSocketPair()
{
fd[0] = -1;
fd[1] = -1;
listening = false;
connectingFd = -1;
shutdown[0] = false;
shutdown[1] = false;
readable[0] = false;
readable[1] = false;
}
};
static thread_local std::ostringstream loggingBuffer;
static void (*loggingCallback)(const std::string&) = nullptr;
static std::mutex theMutex;
static std::condition_variable theCV;
static int fakeSocketLogLevel = 0;
static void fakeSocketDumpStateImpl();
// Avoid problems with order of initialisation of static globals.
static std::vector<FakeSocketPair>& getFds()
{
static std::vector<FakeSocketPair> fds;
return fds;
}
static std::string flush()
{
static bool alwaysStderr = std::getenv("FAKESOCKET_LOG_ALWAYS_STDERR") != nullptr;
if (alwaysStderr)
std::cerr << std::this_thread::get_id() << ':' << loggingBuffer.str() << std::endl;
else if (loggingCallback != nullptr)
loggingCallback(loggingBuffer.str());
loggingBuffer.str("");
return "";
}
#ifdef __ANDROID__
// kill the verbose logging on Android
#define FAKESOCKET_LOG(level, arg)
#else
#define FAKESOCKET_LOG(level, arg) do { if (level <= fakeSocketLogLevel) { loggingBuffer << arg; } } while (false)
#endif
void fakeSocketSetLoggingCallback(void (*callback)(const std::string&))
{
loggingCallback = callback;
}
static int fakeSocketAllocate()
{
if (fakeSocketLogLevel == 0)
{
char *logLevel = std::getenv("FAKESOCKET_LOG_LEVEL");
if (logLevel == nullptr)
fakeSocketLogLevel = 1;
else
{
fakeSocketLogLevel = std::strtol(logLevel, nullptr, 10);
if (fakeSocketLogLevel != 1 && fakeSocketLogLevel != 2)
fakeSocketLogLevel = 1;
}
}
std::vector<FakeSocketPair>& fds = getFds();
std::lock_guard<std::mutex> lock(theMutex);
// We always allocate a new FakeSocketPair struct. Let's not bother with potential issues with
// reusing them. It isn't like we would be allocating thousands anyway during the typical
// lifetime of an app. Also, not reusing FakeSocket fd numbers means that it is easier to set a
// conditional breakpoint on an operation on a specific fd when debugging some problematic
// scenario.
const int i = fds.size();
fds.resize(i + 1);
FakeSocketPair& result = fds[i];
result.fd[0] = i*2;
return i*2;
}
int fakeSocketSocket()
{
const int result = fakeSocketAllocate();
FAKESOCKET_LOG(1, "FakeSocket Create #" << result << flush());
return result;
}
int fakeSocketPipe2(int pipefd[2])
{
pipefd[0] = fakeSocketAllocate();
assert(pipefd[0] >= 0);
std::vector<FakeSocketPair>& fds = getFds();
FakeSocketPair& pair = fds[pipefd[0]/2];
std::unique_lock<std::mutex> lock(theMutex);
assert(pair.fd[0] == pipefd[0]);
pair.fd[1] = pair.fd[0] + 1;
pipefd[1] = pair.fd[1];
FAKESOCKET_LOG(1, "FakeSocket Pipe created (#" << pipefd[0] << ",#" << pipefd[1] << ')' << flush());
return 0;
}
static std::string pollBits(int bits)
{
if (bits == 0)
return "-";
std::string result;
if (bits & POLLERR)
{
if (result != "")
result += '+';
result += "ERR";
}
if (bits & POLLHUP)
{
if (result != "")
result += '+';
result += "HUP";
}
if (bits & POLLIN)
{
if (result != "")
result += '+';
result += "IN";
}
if (bits & POLLNVAL)
{
if (result != "")
result += '+';
result += "NVAL";
}
if (bits & POLLOUT)
{
if (result != "")
result += '+';
result += "OUT";
}
if (bits & POLLPRI)
{
if (result != "")
result += '+';
result += "PRI";
}
return result;
}
static bool checkForPoll(std::vector<FakeSocketPair>& fds, struct pollfd *pollfds, int nfds)
{
bool retval = false;
for (int i = 0; i < nfds; i++)
{
const int K = ((pollfds[i].fd)&1);
const int N = 1 - K;
if (pollfds[i].fd < 0 || static_cast<unsigned>(pollfds[i].fd/2) >= fds.size())
{
pollfds[i].revents = POLLNVAL;
retval = true;
}
else
{
if (fds[pollfds[i].fd/2].fd[K] == -1)
{
pollfds[i].revents = POLLNVAL;
retval = true;
}
else
pollfds[i].revents = 0;
}
if (pollfds[i].revents == 0)
{
if (pollfds[i].events & POLLIN)
{
if (fds[pollfds[i].fd/2].readable[K] ||
(K == 0 && fds[pollfds[i].fd/2].listening && fds[pollfds[i].fd/2].connectingFd != -1))
{
pollfds[i].revents |= POLLIN;
retval = true;
}
}
// With multiple buffers, a socket is always writable unless the peer is closed or shut down
if (pollfds[i].events & POLLOUT)
{
if (fds[pollfds[i].fd/2].fd[N] != -1 && !fds[pollfds[i].fd/2].shutdown[N])
{
pollfds[i].revents |= POLLOUT;
retval = true;
}
}
if (fds[pollfds[i].fd/2].shutdown[N])
{
pollfds[i].revents |= POLLHUP;
retval = true;
}
}
}
return retval;
}
int fakeSocketPoll(struct pollfd *pollfds, int nfds, int timeout)
{
FAKESOCKET_LOG(2, "FakeSocket Poll ");
for (int i = 0; i < nfds; i++)
{
if (i > 0)
FAKESOCKET_LOG(2, ',');
FAKESOCKET_LOG(2, '#' << pollfds[i].fd << ':' << pollBits(pollfds[i].events));
}
FAKESOCKET_LOG(2, ", timeout:" << timeout << flush());
std::vector<FakeSocketPair>& fds = getFds();
std::unique_lock<std::mutex> lock(theMutex);
if (timeout > 0)
{
auto const now = std::chrono::steady_clock::now();
auto const end = now + std::chrono::milliseconds(timeout);
while (!checkForPoll(fds, pollfds, nfds))
if (theCV.wait_until(lock, end) == std::cv_status::timeout)
{
FAKESOCKET_LOG(2, "FakeSocket Poll timeout: 0" << flush());
return 0;
}
}
else if (timeout == 0)
{
checkForPoll(fds, pollfds, nfds);
}
else // timeout < 0
{
while (!checkForPoll(fds, pollfds, nfds))
theCV.wait(lock);
}
int result = 0;
for (int i = 0; i < nfds; i++)
{
if (pollfds[i].revents != 0)
result++;
}
FAKESOCKET_LOG(2, "FakeSocket Poll result: ");
for (int i = 0; i < nfds; i++)
{
if (i > 0)
FAKESOCKET_LOG(2, ',');
FAKESOCKET_LOG(2, '#' << pollfds[i].fd << ':' << pollBits(pollfds[i].revents));
}
FAKESOCKET_LOG(2, ": " << result << flush());
return result;
}
int fakeSocketListen(int fd)
{
std::vector<FakeSocketPair>& fds = getFds();
std::unique_lock<std::mutex> lock(theMutex);
if (fd < 0 || static_cast<unsigned>(fd/2) >= fds.size() || fds[fd/2].fd[fd&1] == -1)
{
FAKESOCKET_LOG(1, "FakeSocket EBADF: Listening on #" << fd << flush());
errno = EBADF;
return -1;
}
FakeSocketPair& pair = fds[fd/2];
if (fd&1 || pair.fd[1] != -1)
{
FAKESOCKET_LOG(1, "FakeSocket EISCONN: Listening on #" << fd << flush());
errno = EISCONN;
return -1;
}
if (pair.listening)
{
FAKESOCKET_LOG(1, "FakeSocket EIO: Listening on #" << fd << flush());
errno = EIO;
return -1;
}
pair.listening = true;
pair.connectingFd = -1;
FAKESOCKET_LOG(1, "FakeSocket Listen #" << fd << flush());
return 0;
}
int fakeSocketConnect(int fd1, int fd2)
{
std::vector<FakeSocketPair>& fds = getFds();
std::unique_lock<std::mutex> lock(theMutex);
if (fd1 < 0 || fd2 < 0 || static_cast<unsigned>(fd1/2) >= fds.size() || static_cast<unsigned>(fd2/2) >= fds.size())
{
FAKESOCKET_LOG(1, "FakeSocket EBADF: Connect #" << fd1 << " to #" << fd2 << flush());
errno = EBADF;
return -1;
}
if (fd1/2 == fd2/2)
{
FAKESOCKET_LOG(1, "FakeSocket EBADF: Connect #" << fd1 << " to #" << fd2 << flush());
errno = EBADF;
return -1;
}
FakeSocketPair& pair1 = fds[fd1/2];
FakeSocketPair& pair2 = fds[fd2/2];
if ((fd1&1) || (fd2&1))
{
FAKESOCKET_LOG(1, "FakeSocket EISCONN: Connect #" << fd1 << " to #" << fd2 << flush());
errno = EISCONN;
return -1;
}
if (!pair2.listening || pair2.connectingFd != -1)
{
FAKESOCKET_LOG(1, "FakeSocket ECONNREFUSED: Connect #" << fd1 << " to #" << fd2 << flush());
errno = ECONNREFUSED;
return -1;
}
pair2.connectingFd = fd1;
theCV.notify_all();
while (pair1.fd[1] == -1)
theCV.wait(lock);
assert(pair1.fd[1] == pair1.fd[0] + 1);
FAKESOCKET_LOG(1, "FakeSocket Connect #" << fd1 << " to #" << fd2 << ": #" << pair1.fd[1] << flush());
return 0;
}
int fakeSocketAccept4(int fd)
{
std::vector<FakeSocketPair>& fds = getFds();
std::unique_lock<std::mutex> lock(theMutex);
if (fd < 0 || static_cast<unsigned>(fd/2) >= fds.size())
{
FAKESOCKET_LOG(1, "FakeSocket EBADF: Accept #" << fd << flush());
errno = EBADF;
return -1;
}
if (fd & 1)
{
FAKESOCKET_LOG(1, "FakeSocket EISCONN: Accept #" << fd << flush());
errno = EISCONN;
return -1;
}
FakeSocketPair& pair = fds[fd/2];
if (!pair.listening)
{
FAKESOCKET_LOG(1, "FakeSocket EIO: Accept #" << fd << flush());
errno = EIO;
return -1;
}
while (pair.connectingFd == -1)
theCV.wait(lock);
assert(pair.connectingFd >= 0);
assert(static_cast<unsigned>(pair.connectingFd/2) < fds.size());
assert((pair.connectingFd&1) == 0);
FakeSocketPair& pair2 = fds[pair.connectingFd/2];
assert(pair2.fd[1] == -1);
assert(pair2.fd[0] == pair.connectingFd);
pair.connectingFd = -1;
pair2.fd[1] = pair2.fd[0] + 1;
theCV.notify_all();
FAKESOCKET_LOG(1, "FakeSocket Accept #" << fd << ": #" << pair2.fd[1] << flush());
fakeSocketDumpStateImpl();
return pair2.fd[1];
}
int fakeSocketPeer(int fd)
{
std::vector<FakeSocketPair>& fds = getFds();
std::unique_lock<std::mutex> lock(theMutex);
if (fd < 0 || static_cast<unsigned>(fd/2) >= fds.size())
{
FAKESOCKET_LOG(1, "FakeSocket EBADF: Peer of #" << fd << flush());
errno = EBADF;
return -1;
}
FakeSocketPair& pair = fds[fd/2];
const int K = (fd&1);
const int N = 1 - K;
FAKESOCKET_LOG(1, "FakeSocket Peer of #" << fd << ": #" << pair.fd[N] << flush());
return pair.fd[N];
}
ssize_t fakeSocketAvailableDataLength(int fd)
{
std::vector<FakeSocketPair>& fds = getFds();
std::unique_lock<std::mutex> lock(theMutex);
if (fd < 0 || static_cast<unsigned>(fd/2) >= fds.size())
{
errno = EBADF;
return -1;
}
FakeSocketPair& pair = fds[fd/2];
// K: for this fd
const int K = (fd&1);
if (!pair.readable[K])
{
FAKESOCKET_LOG(2, "FakeSocket EAGAIN: Available data on #" << fd << flush());
errno = EAGAIN;
return -1;
}
ssize_t result = 0;
if (pair.buffer[K].size() > 0)
result = pair.buffer[K][0].size();
FAKESOCKET_LOG(2, "FakeSocket Available data on #" << fd << ": " << result << flush());
return result;
}
ssize_t fakeSocketRead(int fd, void *buf, size_t nbytes)
{
std::vector<FakeSocketPair>& fds = getFds();
std::unique_lock<std::mutex> lock(theMutex);
if (fd < 0 || static_cast<unsigned>(fd/2) >= fds.size())
{
FAKESOCKET_LOG(2, "FakeSocket EBADF: Read from #" << fd << ", " << nbytes << (nbytes == 1 ? " byte" : " bytes") << flush());
errno = EBADF;
return -1;
}
FakeSocketPair& pair = fds[fd/2];
// K: for this fd
const int K = (fd&1);
// N: for its peer
const int N = 1 - K;
if (pair.fd[K] == -1)
{
FAKESOCKET_LOG(2, "FakeSocket EBADF: Read from #" << fd << ", " << nbytes << (nbytes == 1 ? " byte" : " bytes") << flush());
errno = EBADF;
return -1;
}
if (pair.shutdown[K])
{
FAKESOCKET_LOG(2, "FakeSocket Read from #" << fd << " (shut down) got 0 bytes" << flush());
return 0;
}
if (!pair.readable[K])
{
FAKESOCKET_LOG(2, "FakeSocket EAGAIN: Read from #" << fd << ", " << nbytes << (nbytes == 1 ? " byte" : " bytes") << flush());
errno = EAGAIN;
return -1;
}
ssize_t result = 0;
if (pair.buffer[K].size() > 0)
{
// These sockets are record-oriented. It won't work to read less than the whole record in
// turn to be read.
result = pair.buffer[K][0].size();
if (nbytes < static_cast<unsigned>(result))
{
FAKESOCKET_LOG(2, "FakeSocket EAGAIN: Read from #" << fd << ", " << nbytes << (nbytes == 1 ? " byte" : " bytes") << flush());
errno = EAGAIN; // Not the right errno, but what would be?
return -1;
}
memmove(buf, pair.buffer[K][0].data(), result);
pair.buffer[K].erase(pair.buffer[K].begin());
}
// If peer is closed or shut down, we continue to be readable
if (pair.fd[N] == -1 || pair.shutdown[N])
pair.readable[K] = true;
else if (pair.buffer[K].empty())
pair.readable[K] = false;
FAKESOCKET_LOG(2, "FakeSocket Read from #" << fd << " got " << result << (result == 1 ? " byte" : " bytes") << flush());
return result;
}
ssize_t fakeSocketWrite(int fd, const void *buf, size_t nbytes)
{
std::vector<FakeSocketPair>& fds = getFds();
std::unique_lock<std::mutex> lock(theMutex);
if (fd < 0 || static_cast<unsigned>(fd/2) >= fds.size())
{
FAKESOCKET_LOG(2, "FakeSocket EBADF: Write to #" << fd << ", " << nbytes << (nbytes == 1 ? " byte" : " bytes") << flush());
errno = EBADF;
return -1;
}
FakeSocketPair& pair = fds[fd/2];
// K: for this fd
// N: for its peer, whose read buffer we want to write into
const int K = (fd&1);
const int N = 1 - K;
if (pair.fd[K] == -1)
{
FAKESOCKET_LOG(2, "FakeSocket EBADF: Write to #" << fd << ", " << nbytes << (nbytes == 1 ? " byte" : " bytes") << flush());
errno = EBADF;
return -1;
}
if (pair.shutdown[K])
{
// Should we raise(SIGPIPE)? Probably not, Online code does not expect SIGPIPE at all...
FAKESOCKET_LOG(2, "FakeSocket EPIPE: Write to #" << fd << " (shut down), " << nbytes << (nbytes == 1 ? " byte" : " bytes") << flush());
errno = EPIPE;
return -1;
}
pair.buffer[N].emplace_back(std::vector<char>(nbytes));
memmove(pair.buffer[N].back().data(), buf, nbytes);
pair.readable[N] = true;
theCV.notify_all();
FAKESOCKET_LOG(2, "FakeSocket Write to #" << fd << ": " << nbytes << (nbytes == 1 ? " byte" : " bytes") << flush());
return nbytes;
}
int fakeSocketShutdown(int fd)
{
std::vector<FakeSocketPair>& fds = getFds();
std::unique_lock<std::mutex> lock(theMutex);
if (fd < 0 || static_cast<unsigned>(fd/2) >= fds.size())
{
FAKESOCKET_LOG(1, "FakeSocket EBADF: Shutdown #" << fd << flush());
errno = EBADF;
return -1;
}
FakeSocketPair& pair = fds[fd/2];
const int K = (fd&1);
const int N = 1 - K;
if (pair.fd[K] == -1)
{
FAKESOCKET_LOG(1, "FakeSocket EBADF: Shutdown #" << fd << flush());
errno = EBADF;
return -1;
}
if (pair.fd[N] == -1)
{
FAKESOCKET_LOG(1, "FakeSocket ENOTCONN: Shutdown #" << fd << flush());
errno = ENOTCONN;
return -1;
}
pair.shutdown[K] = true;
pair.readable[K] = true;
theCV.notify_all();
FAKESOCKET_LOG(1, "FakeSocket Shutdown #" << fd << flush());
return 0;
}
int fakeSocketClose(int fd)
{
std::vector<FakeSocketPair>& fds = getFds();
std::unique_lock<std::mutex> lock(theMutex);
if (fd < 0 || static_cast<unsigned>(fd/2) >= fds.size())
{
FAKESOCKET_LOG(1, "FakeSocket EBADF: Close #" << fd << flush());
errno = EBADF;
return -1;
}
FakeSocketPair& pair = fds[fd/2];
const int K = (fd&1);
const int N = 1 - K;
if (pair.fd[K] == -1)
{
FAKESOCKET_LOG(1, "FakeSocket EBADF: Close #" << fd << flush());
errno = EBADF;
return -1;
}
assert(pair.fd[K] == fd);
pair.fd[K] = -1;
pair.buffer[K].resize(0);
pair.readable[N] = true;
theCV.notify_all();
FAKESOCKET_LOG(1, "FakeSocket Close #" << fd << flush());
fakeSocketDumpStateImpl();
return 0;
}
static void fakeSocketDumpStateImpl()
{
std::vector<FakeSocketPair>& fds = getFds();
FAKESOCKET_LOG(1, "FakeSocket open sockets:" << flush());
for (int i = 0; i < static_cast<int>(fds.size()); i++)
{
if (fds[i].fd[0] != -1)
{
assert(fds[i].fd[0] == i*2);
FAKESOCKET_LOG(1, " #" << fds[i].fd[0]);
if (fds[i].fd[1] != -1)
{
assert(fds[i].fd[1] == i*2+1);
assert(!fds[i].listening);
FAKESOCKET_LOG(1, " <=> #" << fds[i].fd[1]);
}
else if (fds[i].listening)
{
FAKESOCKET_LOG(1, " listening");
}
FAKESOCKET_LOG(1, flush());
}
else if (fds[i].fd[1] != -1)
{
assert(fds[i].fd[1] == i*2+1);
assert(!fds[i].listening);
FAKESOCKET_LOG(1, " #" << fds[i].fd[1] << flush());
}
}
}
void fakeSocketDumpState()
{
std::unique_lock<std::mutex> lock(theMutex);
fakeSocketDumpStateImpl();
}
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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