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event.c
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event.c
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/*
event.c -- I/O, timeout and signal event handling
Copyright (C) 2012-2013 Guus Sliepen <guus@tinc-vpn.org>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
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.
*/
#include "system.h"
#include "dropin.h"
#include "event.h"
#include "net.h"
#include "utils.h"
#include "xalloc.h"
#include "logger.h"
struct timeval now;
#ifndef HAVE_MINGW
static fd_set readfds;
static fd_set writefds;
#else
static const long READ_EVENTS = FD_READ | FD_ACCEPT | FD_CLOSE;
static const long WRITE_EVENTS = FD_WRITE | FD_CONNECT;
static DWORD event_count = 0;
#endif
static bool running;
static int io_compare(const io_t *a, const io_t *b) {
#ifndef HAVE_MINGW
return a->fd - b->fd;
#else
return a->event - b->event;
#endif
}
static int timeout_compare(const timeout_t *a, const timeout_t *b) {
struct timeval diff;
timersub(&a->tv, &b->tv, &diff);
if(diff.tv_sec < 0)
return -1;
if(diff.tv_sec > 0)
return 1;
if(diff.tv_usec < 0)
return -1;
if(diff.tv_usec > 0)
return 1;
if(a < b)
return -1;
if(a > b)
return 1;
return 0;
}
static splay_tree_t io_tree = {.compare = (splay_compare_t)io_compare};
static splay_tree_t timeout_tree = {.compare = (splay_compare_t)timeout_compare};
void io_add(io_t *io, io_cb_t cb, void *data, int fd, int flags) {
logger(DEBUG_META, LOG_NOTICE, "io_add(%x, %x, %x, %d, %d)", io, cb, data, fd, flags);
if(io->cb) {
logger(DEBUG_META, LOG_NOTICE, "io_add() ignored because of io->cb");
return;
}
io->fd = fd;
#ifdef HAVE_MINGW
if (io->fd != -1) {
io->event = WSACreateEvent();
if (io->event == WSA_INVALID_EVENT)
abort();
}
event_count++;
#endif
io->cb = cb;
io->data = data;
io->node.data = io;
io_set(io, flags);
if(!splay_insert_node(&io_tree, &io->node))
abort();
}
#ifdef HAVE_MINGW
void io_add_event(io_t *io, io_cb_t cb, void *data, WSAEVENT event) {
io_add(io, cb, data, -1, 0);
io->event = event;
}
#endif
void io_set(io_t *io, int flags) {
logger(DEBUG_META, LOG_NOTICE, "io_set(%x, %d)", io, flags);
if (flags == io->flags) {
logger(DEBUG_META, LOG_NOTICE, "io_set() ignored because no-op");
return;
}
io->flags = flags;
if (io->fd == -1) {
logger(DEBUG_META, LOG_NOTICE, "io_set() ignored because no fd");
return;
}
#ifndef HAVE_MINGW
if(flags & IO_READ)
FD_SET(io->fd, &readfds);
else
FD_CLR(io->fd, &readfds);
if(flags & IO_WRITE)
FD_SET(io->fd, &writefds);
else
FD_CLR(io->fd, &writefds);
#else
long events = 0;
if (flags & IO_WRITE)
events |= WRITE_EVENTS;
if (flags & IO_READ)
events |= READ_EVENTS;
if (WSAEventSelect(io->fd, io->event, events) != 0)
abort();
#endif
}
void io_del(io_t *io) {
logger(DEBUG_META, LOG_NOTICE, "io_del(%x)", io);
if(!io->cb) {
logger(DEBUG_META, LOG_NOTICE, "io_del() ignored because no io->cb");
return;
}
io_set(io, 0);
#ifdef HAVE_MINGW
if (io->fd != -1 && WSACloseEvent(io->event) == FALSE)
abort();
event_count--;
#endif
if (!splay_search(&io_tree, io))
logger(DEBUG_META, LOG_NOTICE, "io_del() called with unknown io");
splay_unlink_node(&io_tree, &io->node);
io->cb = NULL;
}
void timeout_add(timeout_t *timeout, timeout_cb_t cb, void *data, struct timeval *tv) {
timeout->cb = cb;
timeout->data = data;
timeout->node.data = timeout;
timeout_set(timeout, tv);
}
void timeout_set(timeout_t *timeout, struct timeval *tv) {
if(timerisset(&timeout->tv))
splay_unlink_node(&timeout_tree, &timeout->node);
if(!now.tv_sec)
gettimeofday(&now, NULL);
timeradd(&now, tv, &timeout->tv);
if(!splay_insert_node(&timeout_tree, &timeout->node))
abort();
}
void timeout_del(timeout_t *timeout) {
if(!timeout->cb)
return;
splay_unlink_node(&timeout_tree, &timeout->node);
timeout->cb = 0;
timeout->tv = (struct timeval){0, 0};
}
#ifndef HAVE_MINGW
static int signal_compare(const signal_t *a, const signal_t *b) {
return a->signum - b->signum;
}
static io_t signalio;
static int pipefd[2] = {-1, -1};
static splay_tree_t signal_tree = {.compare = (splay_compare_t)signal_compare};
static void signal_handler(int signum) {
unsigned char num = signum;
write(pipefd[1], &num, 1);
}
static void signalio_handler(void *data, int flags) {
unsigned char signum;
if(read(pipefd[0], &signum, 1) != 1)
return;
signal_t *sig = splay_search(&signal_tree, &((signal_t){.signum = signum}));
if(sig)
sig->cb(sig->data);
}
static void pipe_init(void) {
if(!pipe(pipefd))
io_add(&signalio, signalio_handler, NULL, pipefd[0], IO_READ);
}
void signal_add(signal_t *sig, signal_cb_t cb, void *data, int signum) {
if(sig->cb)
return;
sig->cb = cb;
sig->data = data;
sig->signum = signum;
sig->node.data = sig;
if(pipefd[0] == -1)
pipe_init();
signal(sig->signum, signal_handler);
if(!splay_insert_node(&signal_tree, &sig->node))
abort();
}
void signal_del(signal_t *sig) {
if(!sig->cb)
return;
signal(sig->signum, SIG_DFL);
splay_unlink_node(&signal_tree, &sig->node);
sig->cb = NULL;
}
#endif
static struct timeval * get_time_remaining(struct timeval *diff) {
gettimeofday(&now, NULL);
struct timeval *tv = NULL;
while(timeout_tree.head) {
timeout_t *timeout = timeout_tree.head->data;
timersub(&timeout->tv, &now, diff);
if(diff->tv_sec < 0) {
timeout->cb(timeout->data);
if(timercmp(&timeout->tv, &now, <))
timeout_del(timeout);
} else {
tv = diff;
break;
}
}
return tv;
}
bool event_loop(void) {
running = true;
#ifndef HAVE_MINGW
fd_set readable;
fd_set writable;
while(running) {
logger(DEBUG_META, LOG_NOTICE, "event_loop() freezing FD sets");
memcpy(&readable, &readfds, sizeof readable);
memcpy(&writable, &writefds, sizeof writable);
struct timeval diff;
struct timeval *tv = get_time_remaining(&diff);
int fds = 0;
if(io_tree.tail) {
io_t *last = io_tree.tail->data;
fds = last->fd + 1;
}
int n = select(fds, &readable, &writable, NULL, tv);
if(n < 0) {
if(sockwouldblock(sockerrno))
continue;
else
return false;
}
if(!n)
continue;
for splay_each(io_t, io, &io_tree) {
if(FD_ISSET(io->fd, &writable))
io->cb(io->data, IO_WRITE);
else if(FD_ISSET(io->fd, &readable))
io->cb(io->data, IO_READ);
}
}
#else
while (running) {
struct timeval diff;
struct timeval *tv = get_time_remaining(&diff);
DWORD timeout_ms = tv ? (tv->tv_sec * 1000 + tv->tv_usec / 1000 + 1) : WSA_INFINITE;
if (!event_count) {
Sleep(timeout_ms);
continue;
}
/*
For some reason, Microsoft decided to make the FD_WRITE event edge-triggered instead of level-triggered,
which is the opposite of what select() does. In practice, that means that if a FD_WRITE event triggers,
it will never trigger again until a send() returns EWOULDBLOCK. Since the semantics of this event loop
is that write events are level-triggered (i.e. they continue firing until the socket is full), we need
to emulate these semantics by making sure we fire each IO_WRITE that is still writeable.
Note that technically FD_CLOSE has the same problem, but it's okay because user code does not rely on
this event being fired again if ignored.
*/
io_t* writeable_io = NULL;
for splay_each(io_t, io, &io_tree)
if (io->flags & IO_WRITE && send(io->fd, NULL, 0, 0) == 0) {
writeable_io = io;
break;
}
if (writeable_io) {
writeable_io->cb(writeable_io->data, IO_WRITE);
continue;
}
WSAEVENT* events = xmalloc(event_count * sizeof(*events));
DWORD event_index = 0;
for splay_each(io_t, io, &io_tree) {
events[event_index] = io->event;
event_index++;
}
DWORD result = WSAWaitForMultipleEvents(event_count, events, FALSE, timeout_ms, FALSE);
WSAEVENT event;
if (result >= WSA_WAIT_EVENT_0 && result < WSA_WAIT_EVENT_0 + event_count)
event = events[result - WSA_WAIT_EVENT_0];
free(events);
if (result == WSA_WAIT_TIMEOUT)
continue;
if (result < WSA_WAIT_EVENT_0 || result >= WSA_WAIT_EVENT_0 + event_count)
return false;
io_t *io = splay_search(&io_tree, &((io_t){.event = event}));
if (!io)
abort();
if (io->fd == -1) {
io->cb(io->data, 0);
} else {
WSANETWORKEVENTS network_events;
if (WSAEnumNetworkEvents(io->fd, io->event, &network_events) != 0)
return false;
if (network_events.lNetworkEvents & WRITE_EVENTS)
io->cb(io->data, IO_WRITE);
if (network_events.lNetworkEvents & READ_EVENTS)
io->cb(io->data, IO_READ);
}
}
#endif
return true;
}
void event_exit(void) {
running = false;
}