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authorFlorian Weimer <fweimer@redhat.com>2017-02-28 15:28:45 +0100
committerFlorian Weimer <fweimer@redhat.com>2017-02-28 15:36:17 +0100
commitcf0bd2f73bd65beab613865bba567d7787836888 (patch)
tree8cde5a2a9547382fac6546c9397aebbb914cb485 /inet
parent37fb019cb02656d0ce0b8d40d56fe8c42f0d1658 (diff)
downloadglibc-cf0bd2f73bd65beab613865bba567d7787836888.tar.gz
sunrpc: Improvements for UDP client timeout handling [BZ #20257]
This commit fixes various aspects in the UDP client timeout handling. Timeouts are now applied in a more consistent fashion. Discarded UDP packets no longer prevent the timeout from happening at all.
Diffstat (limited to 'inet')
-rw-r--r--inet/Makefile8
-rw-r--r--inet/deadline.c122
-rw-r--r--inet/net-internal.h89
-rw-r--r--inet/tst-deadline.c188
4 files changed, 405 insertions, 2 deletions
diff --git a/inet/Makefile b/inet/Makefile
index 010792af8f..6a7d3e0664 100644
--- a/inet/Makefile
+++ b/inet/Makefile
@@ -45,14 +45,18 @@ routines := htonl htons \
in6_addr getnameinfo if_index ifaddrs inet6_option \
getipv4sourcefilter setipv4sourcefilter \
getsourcefilter setsourcefilter inet6_opt inet6_rth \
- inet6_scopeid_pton
+ inet6_scopeid_pton deadline
aux := check_pf check_native ifreq
tests := htontest test_ifindex tst-ntoa tst-ether_aton tst-network \
tst-gethnm test-ifaddrs bug-if1 test-inet6_opt tst-ether_line \
tst-getni1 tst-getni2 tst-inet6_rth tst-checks tst-checks-posix \
- tst-sockaddr tst-inet6_scopeid_pton test-hnto-types
+ tst-sockaddr tst-inet6_scopeid_pton test-hnto-types tst-deadline
+
+# tst-deadline must be linked statically so that we can access
+# internal functions.
+tests-static += tst-deadline
include ../Rules
diff --git a/inet/deadline.c b/inet/deadline.c
new file mode 100644
index 0000000000..c1fa415a39
--- /dev/null
+++ b/inet/deadline.c
@@ -0,0 +1,122 @@
+/* Computing deadlines for timeouts.
+ Copyright (C) 2017 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <net-internal.h>
+
+#include <assert.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <time.h>
+
+struct deadline_current_time internal_function
+__deadline_current_time (void)
+{
+ struct deadline_current_time result;
+ if (__clock_gettime (CLOCK_MONOTONIC, &result.current) != 0)
+ {
+ struct timeval current_tv;
+ if (__gettimeofday (&current_tv, NULL) == 0)
+ __libc_fatal ("Fatal error: gettimeofday system call failed\n");
+ result.current.tv_sec = current_tv.tv_sec;
+ result.current.tv_nsec = current_tv.tv_usec * 1000;
+ }
+ assert (result.current.tv_sec >= 0);
+ return result;
+}
+
+/* A special deadline value for which __deadline_is_infinite is
+ true. */
+static inline struct deadline
+infinite_deadline (void)
+{
+ return (struct deadline) { { -1, -1 } };
+}
+
+struct deadline internal_function
+__deadline_from_timeval (struct deadline_current_time current,
+ struct timeval tv)
+{
+ assert (__is_timeval_valid_timeout (tv));
+
+ /* Compute second-based deadline. Perform the addition in
+ uintmax_t, which is unsigned, to simply overflow detection. */
+ uintmax_t sec = current.current.tv_sec;
+ sec += tv.tv_sec;
+ if (sec < (uintmax_t) tv.tv_sec)
+ return infinite_deadline ();
+
+ /* Compute nanosecond deadline. */
+ int nsec = current.current.tv_nsec + tv.tv_usec * 1000;
+ if (nsec >= 1000 * 1000 * 1000)
+ {
+ /* Carry nanosecond overflow to seconds. */
+ nsec -= 1000 * 1000 * 1000;
+ if (sec + 1 < sec)
+ return infinite_deadline ();
+ ++sec;
+ }
+ /* This uses a GCC extension, otherwise these casts for detecting
+ overflow would not be defined. */
+ if ((time_t) sec < 0 || sec != (uintmax_t) (time_t) sec)
+ return infinite_deadline ();
+
+ return (struct deadline) { { sec, nsec } };
+}
+
+int internal_function
+__deadline_to_ms (struct deadline_current_time current,
+ struct deadline deadline)
+{
+ if (__deadline_is_infinite (deadline))
+ return INT_MAX;
+
+ if (current.current.tv_sec > deadline.absolute.tv_sec
+ || (current.current.tv_sec == deadline.absolute.tv_sec
+ && current.current.tv_nsec >= deadline.absolute.tv_nsec))
+ return 0;
+ time_t sec = deadline.absolute.tv_sec - current.current.tv_sec;
+ if (sec >= INT_MAX)
+ /* This value will overflow below. */
+ return INT_MAX;
+ int nsec = deadline.absolute.tv_nsec - current.current.tv_nsec;
+ if (nsec < 0)
+ {
+ /* Borrow from the seconds field. */
+ assert (sec > 0);
+ --sec;
+ nsec += 1000 * 1000 * 1000;
+ }
+
+ /* Prepare for rounding up to milliseconds. */
+ nsec += 999999;
+ if (nsec > 1000 * 1000 * 1000)
+ {
+ assert (sec < INT_MAX);
+ ++sec;
+ nsec -= 1000 * 1000 * 1000;
+ }
+
+ unsigned int msec = nsec / (1000 * 1000);
+ if (sec > INT_MAX / 1000)
+ return INT_MAX;
+ msec += sec * 1000;
+ if (msec > INT_MAX)
+ return INT_MAX;
+ return msec;
+}
diff --git a/inet/net-internal.h b/inet/net-internal.h
index 087597ed99..2b2632c7ba 100644
--- a/inet/net-internal.h
+++ b/inet/net-internal.h
@@ -20,11 +20,100 @@
#define _NET_INTERNAL_H 1
#include <arpa/inet.h>
+#include <stdbool.h>
#include <stdint.h>
+#include <sys/time.h>
int __inet6_scopeid_pton (const struct in6_addr *address,
const char *scope, uint32_t *result)
internal_function attribute_hidden;
libc_hidden_proto (__inet6_scopeid_pton)
+
+/* Deadline handling for enforcing timeouts.
+
+ Code should call __deadline_current_time to obtain the current time
+ and cache it locally. The cache needs updating after every
+ long-running or potentially blocking operation. Deadlines relative
+ to the current time can be computed using __deadline_from_timeval.
+ The deadlines may have to be recomputed in response to certain
+ events (such as an incoming packet), but they are absolute (not
+ relative to the current time). A timeout suitable for use with the
+ poll function can be computed from such a deadline using
+ __deadline_to_ms.
+
+ The fields in the structs defined belowed should only be used
+ within the implementation. */
+
+/* Cache of the current time. Used to compute deadlines from relative
+ timeouts and vice versa. */
+struct deadline_current_time
+{
+ struct timespec current;
+};
+
+/* Return the current time. Terminates the process if the current
+ time is not available. */
+struct deadline_current_time __deadline_current_time (void)
+ internal_function attribute_hidden;
+
+/* Computed absolute deadline. */
+struct deadline
+{
+ struct timespec absolute;
+};
+
+
+/* For internal use only. */
+static inline bool
+__deadline_is_infinite (struct deadline deadline)
+{
+ return deadline.absolute.tv_nsec < 0;
+}
+
+/* Return true if the current time is at the deadline or past it. */
+static inline bool
+__deadline_elapsed (struct deadline_current_time current,
+ struct deadline deadline)
+{
+ return !__deadline_is_infinite (deadline)
+ && (current.current.tv_sec > deadline.absolute.tv_sec
+ || (current.current.tv_sec == deadline.absolute.tv_sec
+ && current.current.tv_nsec >= deadline.absolute.tv_nsec));
+}
+
+/* Return the deadline which occurs first. */
+static inline struct deadline
+__deadline_first (struct deadline left, struct deadline right)
+{
+ if (__deadline_is_infinite (right)
+ || left.absolute.tv_sec < right.absolute.tv_sec
+ || (left.absolute.tv_sec == right.absolute.tv_sec
+ && left.absolute.tv_nsec < right.absolute.tv_nsec))
+ return left;
+ else
+ return right;
+}
+
+/* Add TV to the current time and return it. Returns a special
+ infinite absolute deadline on overflow. */
+struct deadline __deadline_from_timeval (struct deadline_current_time,
+ struct timeval tv)
+ internal_function attribute_hidden;
+
+/* Compute the number of milliseconds until the specified deadline,
+ from the current time in the argument. The result is mainly for
+ use with poll. If the deadline has already passed, return 0. If
+ the result would overflow an int, return INT_MAX. */
+int __deadline_to_ms (struct deadline_current_time, struct deadline)
+ internal_function attribute_hidden;
+
+/* Return true if TV.tv_sec is non-negative and TV.tv_usec is in the
+ interval [0, 999999]. */
+static inline bool
+__is_timeval_valid_timeout (struct timeval tv)
+{
+ return tv.tv_sec >= 0 && tv.tv_usec >= 0 && tv.tv_usec < 1000 * 1000;
+}
+
#endif /* _NET_INTERNAL_H */
diff --git a/inet/tst-deadline.c b/inet/tst-deadline.c
new file mode 100644
index 0000000000..ed04345c35
--- /dev/null
+++ b/inet/tst-deadline.c
@@ -0,0 +1,188 @@
+/* Tests for computing deadlines for timeouts.
+ Copyright (C) 2017 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <inet/net-internal.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <support/check.h>
+
+/* Find the maximum value which can be represented in a time_t. */
+static time_t
+time_t_max (void)
+{
+ _Static_assert (0 > (time_t) -1, "time_t is signed");
+ uintmax_t current = 1;
+ while (true)
+ {
+ uintmax_t next = current * 2;
+ /* This cannot happen because time_t is signed. */
+ TEST_VERIFY_EXIT (next > current);
+ ++next;
+ if ((time_t) next < 0 || next != (uintmax_t) (time_t) next)
+ /* Value cannot be represented in time_t. Return the previous
+ value. */
+ return current;
+ current = next;
+ }
+}
+
+static int
+do_test (void)
+{
+ {
+ struct deadline_current_time current_time = __deadline_current_time ();
+ TEST_VERIFY (current_time.current.tv_sec >= 0);
+ current_time = __deadline_current_time ();
+ /* Due to CLOCK_MONOTONIC, either seconds or nanoseconds are
+ greater than zero. This is also true for the gettimeofday
+ fallback. */
+ TEST_VERIFY (current_time.current.tv_sec >= 0);
+ TEST_VERIFY (current_time.current.tv_sec > 0
+ || current_time.current.tv_nsec > 0);
+ }
+
+ /* Check basic computations of deadlines. */
+ struct deadline_current_time current_time = { { 1, 123456789 } };
+ struct deadline deadline = __deadline_from_timeval
+ (current_time, (struct timeval) { 0, 1 });
+ TEST_VERIFY (deadline.absolute.tv_sec == 1);
+ TEST_VERIFY (deadline.absolute.tv_nsec == 123457789);
+ TEST_VERIFY (__deadline_to_ms (current_time, deadline) == 1);
+
+ deadline = __deadline_from_timeval
+ (current_time, ((struct timeval) { 0, 2 }));
+ TEST_VERIFY (deadline.absolute.tv_sec == 1);
+ TEST_VERIFY (deadline.absolute.tv_nsec == 123458789);
+ TEST_VERIFY (__deadline_to_ms (current_time, deadline) == 1);
+
+ deadline = __deadline_from_timeval
+ (current_time, ((struct timeval) { 1, 0 }));
+ TEST_VERIFY (deadline.absolute.tv_sec == 2);
+ TEST_VERIFY (deadline.absolute.tv_nsec == 123456789);
+ TEST_VERIFY (__deadline_to_ms (current_time, deadline) == 1000);
+
+ /* Check if timeouts are correctly rounded up to the next
+ millisecond. */
+ for (int i = 0; i < 999999; ++i)
+ {
+ ++current_time.current.tv_nsec;
+ TEST_VERIFY (__deadline_to_ms (current_time, deadline) == 1000);
+ }
+
+ /* A full millisecond has elapsed, so the time to the deadline is
+ now less than 1000. */
+ ++current_time.current.tv_nsec;
+ TEST_VERIFY (__deadline_to_ms (current_time, deadline) == 999);
+
+ /* Check __deadline_to_ms carry-over. */
+ current_time = (struct deadline_current_time) { { 9, 123456789 } };
+ deadline = (struct deadline) { { 10, 122456789 } };
+ TEST_VERIFY (__deadline_to_ms (current_time, deadline) == 999);
+ deadline = (struct deadline) { { 10, 122456790 } };
+ TEST_VERIFY (__deadline_to_ms (current_time, deadline) == 1000);
+ deadline = (struct deadline) { { 10, 123456788 } };
+ TEST_VERIFY (__deadline_to_ms (current_time, deadline) == 1000);
+ deadline = (struct deadline) { { 10, 123456789 } };
+ TEST_VERIFY (__deadline_to_ms (current_time, deadline) == 1000);
+
+ /* Check __deadline_to_ms overflow. */
+ deadline = (struct deadline) { { INT_MAX - 1, 1 } };
+ TEST_VERIFY (__deadline_to_ms (current_time, deadline) == INT_MAX);
+
+ /* Check __deadline_to_ms for elapsed deadlines. */
+ current_time = (struct deadline_current_time) { { 9, 123456789 } };
+ deadline.absolute = current_time.current;
+ TEST_VERIFY (__deadline_to_ms (current_time, deadline) == 0);
+ current_time = (struct deadline_current_time) { { 9, 123456790 } };
+ TEST_VERIFY (__deadline_to_ms (current_time, deadline) == 0);
+ current_time = (struct deadline_current_time) { { 10, 0 } };
+ TEST_VERIFY (__deadline_to_ms (current_time, deadline) == 0);
+ current_time = (struct deadline_current_time) { { 10, 123456788 } };
+ TEST_VERIFY (__deadline_to_ms (current_time, deadline) == 0);
+ current_time = (struct deadline_current_time) { { 10, 123456789 } };
+ TEST_VERIFY (__deadline_to_ms (current_time, deadline) == 0);
+
+ /* Check carry-over in __deadline_from_timeval. */
+ current_time = (struct deadline_current_time) { { 9, 998000001 } };
+ for (int i = 0; i < 2000; ++i)
+ {
+ deadline = __deadline_from_timeval
+ (current_time, (struct timeval) { 1, i });
+ TEST_VERIFY (deadline.absolute.tv_sec == 10);
+ TEST_VERIFY (deadline.absolute.tv_nsec == 998000001 + i * 1000);
+ }
+ for (int i = 2000; i < 3000; ++i)
+ {
+ deadline = __deadline_from_timeval
+ (current_time, (struct timeval) { 2, i });
+ TEST_VERIFY (deadline.absolute.tv_sec == 12);
+ TEST_VERIFY (deadline.absolute.tv_nsec == 1 + (i - 2000) * 1000);
+ }
+
+ /* Check infinite deadlines. */
+ deadline = __deadline_from_timeval
+ ((struct deadline_current_time) { { 0, 1000 * 1000 * 1000 - 1000 } },
+ (struct timeval) { time_t_max (), 1 });
+ TEST_VERIFY (__deadline_is_infinite (deadline));
+ deadline = __deadline_from_timeval
+ ((struct deadline_current_time) { { 0, 1000 * 1000 * 1000 - 1001 } },
+ (struct timeval) { time_t_max (), 1 });
+ TEST_VERIFY (!__deadline_is_infinite (deadline));
+ deadline = __deadline_from_timeval
+ ((struct deadline_current_time)
+ { { time_t_max (), 1000 * 1000 * 1000 - 1000 } },
+ (struct timeval) { 0, 1 });
+ TEST_VERIFY (__deadline_is_infinite (deadline));
+ deadline = __deadline_from_timeval
+ ((struct deadline_current_time)
+ { { time_t_max () / 2 + 1, 0 } },
+ (struct timeval) { time_t_max () / 2 + 1, 0 });
+ TEST_VERIFY (__deadline_is_infinite (deadline));
+
+ /* Check __deadline_first behavior. */
+ deadline = __deadline_first
+ ((struct deadline) { { 1, 2 } },
+ (struct deadline) { { 1, 3 } });
+ TEST_VERIFY (deadline.absolute.tv_sec == 1);
+ TEST_VERIFY (deadline.absolute.tv_nsec == 2);
+ deadline = __deadline_first
+ ((struct deadline) { { 1, 3 } },
+ (struct deadline) { { 1, 2 } });
+ TEST_VERIFY (deadline.absolute.tv_sec == 1);
+ TEST_VERIFY (deadline.absolute.tv_nsec == 2);
+ deadline = __deadline_first
+ ((struct deadline) { { 1, 2 } },
+ (struct deadline) { { 2, 1 } });
+ TEST_VERIFY (deadline.absolute.tv_sec == 1);
+ TEST_VERIFY (deadline.absolute.tv_nsec == 2);
+ deadline = __deadline_first
+ ((struct deadline) { { 1, 2 } },
+ (struct deadline) { { 2, 4 } });
+ TEST_VERIFY (deadline.absolute.tv_sec == 1);
+ TEST_VERIFY (deadline.absolute.tv_nsec == 2);
+ deadline = __deadline_first
+ ((struct deadline) { { 2, 4 } },
+ (struct deadline) { { 1, 2 } });
+ TEST_VERIFY (deadline.absolute.tv_sec == 1);
+ TEST_VERIFY (deadline.absolute.tv_nsec == 2);
+
+ return 0;
+}
+
+#include <support/test-driver.c>