quic_reactor.c
/*
* Copyright 2022-2023 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include "internal/quic_reactor.h"
#include "internal/common.h"
#include "internal/thread_arch.h"
/*
* Core I/O Reactor Framework
* ==========================
*/
void ossl_quic_reactor_init(QUIC_REACTOR *rtor,
void (*tick_cb)(QUIC_TICK_RESULT *res, void *arg,
uint32_t flags),
void *tick_cb_arg,
OSSL_TIME initial_tick_deadline)
{
rtor->poll_r.type = BIO_POLL_DESCRIPTOR_TYPE_NONE;
rtor->poll_w.type = BIO_POLL_DESCRIPTOR_TYPE_NONE;
rtor->net_read_desired = 0;
rtor->net_write_desired = 0;
rtor->can_poll_r = 0;
rtor->can_poll_w = 0;
rtor->tick_deadline = initial_tick_deadline;
rtor->tick_cb = tick_cb;
rtor->tick_cb_arg = tick_cb_arg;
}
void ossl_quic_reactor_set_poll_r(QUIC_REACTOR *rtor, const BIO_POLL_DESCRIPTOR *r)
{
if (r == NULL)
rtor->poll_r.type = BIO_POLL_DESCRIPTOR_TYPE_NONE;
else
rtor->poll_r = *r;
rtor->can_poll_r
= ossl_quic_reactor_can_support_poll_descriptor(rtor, &rtor->poll_r);
}
void ossl_quic_reactor_set_poll_w(QUIC_REACTOR *rtor, const BIO_POLL_DESCRIPTOR *w)
{
if (w == NULL)
rtor->poll_w.type = BIO_POLL_DESCRIPTOR_TYPE_NONE;
else
rtor->poll_w = *w;
rtor->can_poll_w
= ossl_quic_reactor_can_support_poll_descriptor(rtor, &rtor->poll_w);
}
const BIO_POLL_DESCRIPTOR *ossl_quic_reactor_get_poll_r(const QUIC_REACTOR *rtor)
{
return &rtor->poll_r;
}
const BIO_POLL_DESCRIPTOR *ossl_quic_reactor_get_poll_w(const QUIC_REACTOR *rtor)
{
return &rtor->poll_w;
}
int ossl_quic_reactor_can_support_poll_descriptor(const QUIC_REACTOR *rtor,
const BIO_POLL_DESCRIPTOR *d)
{
return d->type == BIO_POLL_DESCRIPTOR_TYPE_SOCK_FD;
}
int ossl_quic_reactor_can_poll_r(const QUIC_REACTOR *rtor)
{
return rtor->can_poll_r;
}
int ossl_quic_reactor_can_poll_w(const QUIC_REACTOR *rtor)
{
return rtor->can_poll_w;
}
int ossl_quic_reactor_net_read_desired(QUIC_REACTOR *rtor)
{
return rtor->net_read_desired;
}
int ossl_quic_reactor_net_write_desired(QUIC_REACTOR *rtor)
{
return rtor->net_write_desired;
}
OSSL_TIME ossl_quic_reactor_get_tick_deadline(QUIC_REACTOR *rtor)
{
return rtor->tick_deadline;
}
int ossl_quic_reactor_tick(QUIC_REACTOR *rtor, uint32_t flags)
{
QUIC_TICK_RESULT res = {0};
/*
* Note that the tick callback cannot fail; this is intentional. Arguably it
* does not make that much sense for ticking to 'fail' (in the sense of an
* explicit error indicated to the user) because ticking is by its nature
* best effort. If something fatal happens with a connection we can report
* it on the next actual application I/O call.
*/
rtor->tick_cb(&res, rtor->tick_cb_arg, flags);
rtor->net_read_desired = res.net_read_desired;
rtor->net_write_desired = res.net_write_desired;
rtor->tick_deadline = res.tick_deadline;
return 1;
}
/*
* Blocking I/O Adaptation Layer
* =============================
*/
/*
* Utility which can be used to poll on up to two FDs. This is designed to
* support use of split FDs (e.g. with SSL_set_rfd and SSL_set_wfd where
* different FDs are used for read and write).
*
* Generally use of poll(2) is preferred where available. Windows, however,
* hasn't traditionally offered poll(2), only select(2). WSAPoll() was
* introduced in Vista but has seemingly been buggy until relatively recent
* versions of Windows 10. Moreover we support XP so this is not a suitable
* target anyway. However, the traditional issues with select(2) turn out not to
* be an issue on Windows; whereas traditional *NIX select(2) uses a bitmap of
* FDs (and thus is limited in the magnitude of the FDs expressible), Windows
* select(2) is very different. In Windows, socket handles are not allocated
* contiguously from zero and thus this bitmap approach was infeasible. Thus in
* adapting the Berkeley sockets API to Windows a different approach was taken
* whereby the fd_set contains a fixed length array of socket handles and an
* integer indicating how many entries are valid; thus Windows select()
* ironically is actually much more like *NIX poll(2) than *NIX select(2). In
* any case, this means that the relevant limit for Windows select() is the
* number of FDs being polled, not the magnitude of those FDs. Since we only
* poll for two FDs here, this limit does not concern us.
*
* Usage: rfd and wfd may be the same or different. Either or both may also be
* -1. If rfd_want_read is 1, rfd is polled for readability, and if
* wfd_want_write is 1, wfd is polled for writability. Note that since any
* passed FD is always polled for error conditions, setting rfd_want_read=0 and
* wfd_want_write=0 is not the same as passing -1 for both FDs.
*
* deadline is a timestamp to return at. If it is ossl_time_infinite(), the call
* never times out.
*
* Returns 0 on error and 1 on success. Timeout expiry is considered a success
* condition. We don't elaborate our return values here because the way we are
* actually using this doesn't currently care.
*
* If mutex is non-NULL, it is assumed to be held for write and is unlocked for
* the duration of the call.
*
* Precondition: mutex is NULL or is held for write (unchecked)
* Postcondition: mutex is NULL or is held for write (unless
* CRYPTO_THREAD_write_lock fails)
*/
static int poll_two_fds(int rfd, int rfd_want_read,
int wfd, int wfd_want_write,
OSSL_TIME deadline,
CRYPTO_MUTEX *mutex)
{
#if defined(OPENSSL_SYS_WINDOWS) || !defined(POLLIN)
fd_set rfd_set, wfd_set, efd_set;
OSSL_TIME now, timeout;
struct timeval tv, *ptv;
int maxfd, pres;
# ifndef OPENSSL_SYS_WINDOWS
/*
* On Windows there is no relevant limit to the magnitude of a fd value (see
* above). On *NIX the fd_set uses a bitmap and we must check the limit.
*/
if (rfd >= FD_SETSIZE || wfd >= FD_SETSIZE)
return 0;
# endif
FD_ZERO(&rfd_set);
FD_ZERO(&wfd_set);
FD_ZERO(&efd_set);
if (rfd != -1 && rfd_want_read)
openssl_fdset(rfd, &rfd_set);
if (wfd != -1 && wfd_want_write)
openssl_fdset(wfd, &wfd_set);
/* Always check for error conditions. */
if (rfd != -1)
openssl_fdset(rfd, &efd_set);
if (wfd != -1)
openssl_fdset(wfd, &efd_set);
maxfd = rfd;
if (wfd > maxfd)
maxfd = wfd;
if (!ossl_assert(rfd != -1 || wfd != -1
|| !ossl_time_is_infinite(deadline)))
/* Do not block forever; should not happen. */
return 0;
# if defined(OPENSSL_THREADS)
if (mutex != NULL)
ossl_crypto_mutex_unlock(mutex);
# endif
do {
/*
* select expects a timeout, not a deadline, so do the conversion.
* Update for each call to ensure the correct value is used if we repeat
* due to EINTR.
*/
if (ossl_time_is_infinite(deadline)) {
ptv = NULL;
} else {
now = ossl_time_now();
/*
* ossl_time_subtract saturates to zero so we don't need to check if
* now > deadline.
*/
timeout = ossl_time_subtract(deadline, now);
tv = ossl_time_to_timeval(timeout);
ptv = &tv;
}
pres = select(maxfd + 1, &rfd_set, &wfd_set, &efd_set, ptv);
} while (pres == -1 && get_last_socket_error_is_eintr());
# if defined(OPENSSL_THREADS)
if (mutex != NULL)
ossl_crypto_mutex_lock(mutex);
# endif
return pres < 0 ? 0 : 1;
#else
int pres, timeout_ms;
OSSL_TIME now, timeout;
struct pollfd pfds[2] = {0};
size_t npfd = 0;
if (rfd == wfd) {
pfds[npfd].fd = rfd;
pfds[npfd].events = (rfd_want_read ? POLLIN : 0)
| (wfd_want_write ? POLLOUT : 0);
if (rfd >= 0 && pfds[npfd].events != 0)
++npfd;
} else {
pfds[npfd].fd = rfd;
pfds[npfd].events = (rfd_want_read ? POLLIN : 0);
if (rfd >= 0 && pfds[npfd].events != 0)
++npfd;
pfds[npfd].fd = wfd;
pfds[npfd].events = (wfd_want_write ? POLLOUT : 0);
if (wfd >= 0 && pfds[npfd].events != 0)
++npfd;
}
if (!ossl_assert(npfd != 0 || !ossl_time_is_infinite(deadline)))
/* Do not block forever; should not happen. */
return 0;
# if defined(OPENSSL_THREADS)
if (mutex != NULL)
ossl_crypto_mutex_unlock(mutex);
# endif
do {
if (ossl_time_is_infinite(deadline)) {
timeout_ms = -1;
} else {
now = ossl_time_now();
timeout = ossl_time_subtract(deadline, now);
timeout_ms = ossl_time2ms(timeout);
}
pres = poll(pfds, npfd, timeout_ms);
} while (pres == -1 && get_last_socket_error_is_eintr());
# if defined(OPENSSL_THREADS)
if (mutex != NULL)
ossl_crypto_mutex_lock(mutex);
# endif
return pres < 0 ? 0 : 1;
#endif
}
static int poll_descriptor_to_fd(const BIO_POLL_DESCRIPTOR *d, int *fd)
{
if (d == NULL || d->type == BIO_POLL_DESCRIPTOR_TYPE_NONE) {
*fd = INVALID_SOCKET;
return 1;
}
if (d->type != BIO_POLL_DESCRIPTOR_TYPE_SOCK_FD
|| d->value.fd == INVALID_SOCKET)
return 0;
*fd = d->value.fd;
return 1;
}
/*
* Poll up to two abstract poll descriptors. Currently we only support
* poll descriptors which represent FDs.
*
* If mutex is non-NULL, it is assumed be a lock currently held for write and is
* unlocked for the duration of any wait.
*
* Precondition: mutex is NULL or is held for write (unchecked)
* Postcondition: mutex is NULL or is held for write (unless
* CRYPTO_THREAD_write_lock fails)
*/
static int poll_two_descriptors(const BIO_POLL_DESCRIPTOR *r, int r_want_read,
const BIO_POLL_DESCRIPTOR *w, int w_want_write,
OSSL_TIME deadline,
CRYPTO_MUTEX *mutex)
{
int rfd, wfd;
if (!poll_descriptor_to_fd(r, &rfd)
|| !poll_descriptor_to_fd(w, &wfd))
return 0;
return poll_two_fds(rfd, r_want_read, wfd, w_want_write, deadline, mutex);
}
/*
* Block until a predicate function evaluates to true.
*
* If mutex is non-NULL, it is assumed be a lock currently held for write and is
* unlocked for the duration of any wait.
*
* Precondition: Must hold channel write lock (unchecked)
* Precondition: mutex is NULL or is held for write (unchecked)
* Postcondition: mutex is NULL or is held for write (unless
* CRYPTO_THREAD_write_lock fails)
*/
int ossl_quic_reactor_block_until_pred(QUIC_REACTOR *rtor,
int (*pred)(void *arg), void *pred_arg,
uint32_t flags,
CRYPTO_MUTEX *mutex)
{
int res;
for (;;) {
if ((flags & SKIP_FIRST_TICK) != 0)
flags &= ~SKIP_FIRST_TICK;
else
/* best effort */
ossl_quic_reactor_tick(rtor, 0);
if ((res = pred(pred_arg)) != 0)
return res;
if (!poll_two_descriptors(ossl_quic_reactor_get_poll_r(rtor),
ossl_quic_reactor_net_read_desired(rtor),
ossl_quic_reactor_get_poll_w(rtor),
ossl_quic_reactor_net_write_desired(rtor),
ossl_quic_reactor_get_tick_deadline(rtor),
mutex))
/*
* We don't actually care why the call succeeded (timeout, FD
* readiness), we just call reactor_tick and start trying to do I/O
* things again. If poll_two_fds returns 0, this is some other
* non-timeout failure and we should stop here.
*
* TODO(QUIC FUTURE): In the future we could avoid unnecessary
* syscalls by not retrying network I/O that isn't ready based
* on the result of the poll call. However this might be difficult
* because it requires we do the call to poll(2) or equivalent
* syscall ourselves, whereas in the general case the application
* does the polling and just calls SSL_handle_events().
* Implementing this optimisation in the future will probably
* therefore require API changes.
*/
return 0;
}
}
