diff options
Diffstat (limited to 'src/usr.sbin/rdate/ntpleaps.c')
| -rw-r--r-- | src/usr.sbin/rdate/ntpleaps.c | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/src/usr.sbin/rdate/ntpleaps.c b/src/usr.sbin/rdate/ntpleaps.c new file mode 100644 index 0000000..8c9323e --- /dev/null +++ b/src/usr.sbin/rdate/ntpleaps.c @@ -0,0 +1,196 @@ +/* $OpenBSD: ntpleaps.c,v 1.13 2014/10/08 04:48:22 deraadt Exp $ */ + +/* + * Copyright (c) 2002 Thorsten Glaser. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * - Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * - Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following + * disclaimer in the documentation and/or other materials provided + * with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER + * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + */ + +/* Leap second support for NTP clients (generic) */ + +/* + * I could include tzfile.h, but this would make the code unportable + * at no real benefit. Read tzfile.h for why. + */ + +#include <sys/types.h> +#include <netinet/in.h> + +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +#include "ntpleaps.h" + +static u_int64_t *leapsecs; +static unsigned int leapsecs_num; + +u_int32_t read_be_dword(u_int8_t *ptr); + + +int +ntpleaps_init(void) +{ + static int doneinit; + static int donewarn; + + if (doneinit) + return (0); + + if (ntpleaps_read() == 0) { + doneinit = 1; + return (0); + } + + /* This does not really hurt, but users will complain about + * off-by-22-seconds (at time of coding) errors if we don't warn. + */ + if (!donewarn) { + fputs("Warning: error reading tzfile. You will NOT be\n" + "able to get legal time or posix compliance!\n", stderr); + donewarn = 1; /* put it only once */ + } + + return (-1); +} + +int +ntpleaps_sub(u_int64_t *t) +{ + unsigned int i = 0; + u_int64_t u; + int r = 1; + + if (ntpleaps_init() == -1) + return (-1); + + u = *t; + + while (i < leapsecs_num) { + if (u < leapsecs[i]) { + r--; + break; + } + if (u == leapsecs[i++]) + break; + } + + *t = u - i; + return (r); +} + +u_int32_t +read_be_dword(u_int8_t *ptr) +{ + u_int32_t res; + + memcpy(&res, ptr, 4); + return (ntohl(res)); +} + + +int +ntpleaps_read(void) +{ + int fd; + unsigned int r; + u_int8_t buf[32]; + u_int32_t m1, m2, m3; + u_int64_t s; + u_int64_t *l; + + fd = open("/usr/share/zoneinfo/right/UTC", O_RDONLY | O_NDELAY); + if (fd == -1) + return (-1); + + /* Check signature */ + read(fd, buf, 4); + buf[4] = 0; + if (strcmp((const char *)buf, "TZif")) { + close(fd); + return (-1); + } + + /* Pre-initialize buf[24..27] so we need not check read(2) result */ + buf[24] = 0; + buf[25] = 0; + buf[26] = 0; + buf[27] = 0; + + /* Skip uninteresting parts of header */ + read(fd, buf, 28); + + /* Read number of leap second entries */ + r = read_be_dword(&buf[24]); + /* Check for plausibility - arbitrary values */ + if ((r < 20) || (r > 60000)) { + close(fd); + return (-1); + } + if ((l = reallocarray(NULL, r, sizeof(u_int64_t))) == NULL) { + close(fd); + return (-1); + } + + /* Skip further uninteresting stuff */ + read(fd, buf, 12); + m1 = read_be_dword(buf); + m2 = read_be_dword(&buf[4]); + m3 = read_be_dword(&buf[8]); + m3 += (m1 << 2)+m1+(m2 << 2)+(m2 << 1); + lseek(fd, (off_t)m3, SEEK_CUR); + + /* Now go parse the tzfile leap second info */ + for (m1 = 0; m1 < r; m1++) { + if (read(fd, buf, 8) != 8) { + free(l); + close(fd); + return (-1); + } + s = SEC_TO_TAI64(read_be_dword(buf)); + /* + * Assume just _one_ leap second on each entry, and compensate + * the lacking error checking by validating the first entry + * against the known value + */ + if (!m1 && s != 0x4000000004B2580AULL) { + free(l); + close(fd); + return (-1); + } + l[m1] = s; + } + + /* Clean up and activate the table */ + close(fd); + if (leapsecs != NULL) + free(leapsecs); + leapsecs = l; + leapsecs_num = r; + return (0); +} |