1 files changed, 216 insertions, 0 deletions
diff --git a/devpollmplexer.cc b/devpollmplexer.cc
new file mode 100644
index 0000000..37a0d48
--- /dev/null
+++ b/devpollmplexer.cc
@@ -0,0 +1,216 @@
+/*
+ * This file is part of PowerDNS or dnsdist.
+ * Copyright -- PowerDNS.COM B.V. and its contributors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * In addition, for the avoidance of any doubt, permission is granted to
+ * link this program with OpenSSL and to (re)distribute the binaries
+ * produced as the result of such linking.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+/*
+ * NOTE: sys/devpoll.h relies on sigset_t being already defined so we need
+ * to include sys/signal.h *before* including sys/devpoll.h.
+ */
+#include <sys/signal.h>
+#include <sys/devpoll.h>
+#include "mplexer.hh"
+#include "sstuff.hh"
+#include <iostream>
+#include <unistd.h>
+#include "misc.hh"
+
+#include "namespaces.hh"
+
+class DevPollFDMultiplexer : public FDMultiplexer
+{
+public:
+  DevPollFDMultiplexer();
+  ~DevPollFDMultiplexer()
+  {
+    if (d_devpollfd >= 0) {
+      close(d_devpollfd);
+    }
+  }
+
+  int run(struct timeval* tv, int timeout = 500) override;
+  void getAvailableFDs(std::vector<int>& fds, int timeout) override;
+
+  void addFD(int fd, FDMultiplexer::EventKind kind) override;
+  void removeFD(int fd, FDMultiplexer::EventKind kind) override;
+
+  string getName() const override
+  {
+    return "/dev/poll";
+  }
+
+private:
+  int d_devpollfd;
+};
+
+static FDMultiplexer* makeDevPoll()
+{
+  return new DevPollFDMultiplexer();
+}
+
+static struct DevPollRegisterOurselves
+{
+  DevPollRegisterOurselves()
+  {
+    FDMultiplexer::getMultiplexerMap().emplace(1, &makeDevPoll); // priority 1, so that /dev/poll is preferred over poll, but not over completion ports!
+  }
+} doItDevPoll;
+
+DevPollFDMultiplexer::DevPollFDMultiplexer()
+{
+  d_devpollfd = open("/dev/poll", O_RDWR);
+  if (d_devpollfd < 0) {
+    throw FDMultiplexerException("Setting up /dev/poll: " + stringerror());
+  }
+}
+
+static int convertEventKind(FDMultiplexer::EventKind kind)
+{
+  switch (kind) {
+  case FDMultiplexer::EventKind::Read:
+    return POLLIN;
+  case FDMultiplexer::EventKind::Write:
+    return POLLOUT;
+  case FDMultiplexer::EventKind::Both:
+    return POLLIN | POLLOUT;
+  }
+  throw std::runtime_error("Unhandled event kind in the /dev/poll multiplexer");
+}
+
+void DevPollFDMultiplexer::addFD(int fd, FDMultiplexer::EventKind kind)
+{
+  struct pollfd devent;
+  devent.fd = fd;
+  devent.events = convertEventKind(kind);
+  devent.revents = 0;
+
+  if (write(d_devpollfd, &devent, sizeof(devent)) != sizeof(devent)) {
+    throw FDMultiplexerException("Adding fd to /dev/poll/ set: " + stringerror());
+  }
+}
+
+void DevPollFDMultiplexer::removeFD(int fd, FDMultiplexer::EventKind)
+{
+  struct pollfd devent;
+  devent.fd = fd;
+  devent.events = POLLREMOVE;
+  devent.revents = 0;
+
+  if (write(d_devpollfd, &devent, sizeof(devent)) != sizeof(devent)) {
+    throw FDMultiplexerException("Removing fd from epoll set: " + stringerror());
+  }
+}
+
+void DevPollFDMultiplexer::getAvailableFDs(std::vector<int>& fds, int timeout)
+{
+  std::vector<struct pollfd> pollfds(d_readCallbacks.size() + d_writeCallbacks.size());
+  struct dvpoll dvp;
+  dvp.dp_nfds = d_readCallbacks.size() + d_writeCallbacks.size();
+  dvp.dp_fds = pollfds.data();
+  dvp.dp_timeout = timeout;
+  int ret = ioctl(d_devpollfd, DP_POLL, &dvp);
+
+  if (ret < 0 && errno != EINTR) {
+    throw FDMultiplexerException("/dev/poll returned error: " + stringerror());
+  }
+
+  for (int n = 0; n < ret; ++n) {
+    fds.push_back(pollfds.at(n).fd);
+  }
+}
+
+int DevPollFDMultiplexer::run(struct timeval* now, int timeout)
+{
+  if (d_inrun) {
+    throw FDMultiplexerException("FDMultiplexer::run() is not reentrant!\n");
+  }
+  std::vector<struct pollfd> fds(d_readCallbacks.size() + d_writeCallbacks.size());
+  struct dvpoll dvp;
+  dvp.dp_nfds = d_readCallbacks.size() + d_writeCallbacks.size();
+  dvp.dp_fds = fds.data();
+  dvp.dp_timeout = timeout;
+  int ret = ioctl(d_devpollfd, DP_POLL, &dvp);
+  int err = errno;
+  gettimeofday(now, nullptr); // MANDATORY!
+
+  if (ret < 0 && err != EINTR) {
+    throw FDMultiplexerException("/dev/poll returned error: " + stringerror(err));
+  }
+
+  if (ret < 1) { // thanks AB!
+    return 0;
+  }
+
+  d_inrun = true;
+  int count = 0;
+  for (int n = 0; n < ret; ++n) {
+    if ((fds.at(n).revents & POLLIN) || (fds.at(n).revents & POLLERR) || (fds.at(n).revents & POLLHUP)) {
+      const auto& iter = d_readCallbacks.find(fds.at(n).fd);
+      if (iter != d_readCallbacks.end()) {
+        iter->d_callback(iter->d_fd, iter->d_parameter);
+        count++;
+      }
+    }
+
+    if ((fds.at(n).revents & POLLOUT) || (fds.at(n).revents & POLLERR)) {
+      const auto& iter = d_writeCallbacks.find(fds.at(n).fd);
+      if (iter != d_writeCallbacks.end()) {
+        iter->d_callback(iter->d_fd, iter->d_parameter);
+        count++;
+      }
+    }
+  }
+
+  d_inrun = false;
+  return count;
+}
+
+#if 0
+void acceptData(int fd, funcparam_t& parameter)
+{
+  cout<<"Have data on fd "<<fd<<endl;
+  Socket* sock=funcparam_t_cast<Socket*>(parameter);
+  string packet;
+  IPEndpoint rem;
+  sock->recvFrom(packet, rem);
+  cout<<"Received "<<packet.size()<<" bytes!\n";
+}
+
+
+int main()
+{
+  Socket s(AF_INET, SOCK_DGRAM);
+
+  IPEndpoint loc("0.0.0.0", 2000);
+  s.bind(loc);
+
+  DevPollFDMultiplexer sfm;
+
+  sfm.addReadFD(s.getHandle(), &acceptData, &s);
+
+  for(int n=0; n < 100 ; ++n) {
+    sfm.run();
+  }
+  sfm.removeReadFD(s.getHandle());
+  sfm.removeReadFD(s.getHandle());
+}
+#endif