diff options
Diffstat (limited to 'inet')
| -rw-r--r-- | inet/Makefile | 8 | ||||
| -rw-r--r-- | inet/deadline.c | 122 | ||||
| -rw-r--r-- | inet/net-internal.h | 89 | ||||
| -rw-r--r-- | inet/tst-deadline.c | 188 |
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 (¤t_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> |