1 /*
2 * Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that: (1) source code distributions
7 * retain the above copyright notice and this paragraph in its entirety, (2)
8 * distributions including binary code include the above copyright notice and
9 * this paragraph in its entirety in the documentation or other materials
10 * provided with the distribution, and (3) all advertising materials mentioning
11 * features or use of this software display the following acknowledgement:
12 * ``This product includes software developed by the University of California,
13 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
14 * the University nor the names of its contributors may be used to endorse
15 * or promote products derived from this software without specific prior
16 * written permission.
17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
18 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
20 *
21 */
22
23 #include <config.h>
24
25 #include "ntp.h"
26
27 #include "extract.h"
28
29 #define JAN_1970 INT64_T_CONSTANT(2208988800) /* 1970 - 1900 in seconds */
30
31 void
p_ntp_time(netdissect_options * ndo,const struct l_fixedpt * lfp)32 p_ntp_time(netdissect_options *ndo,
33 const struct l_fixedpt *lfp)
34 {
35 uint32_t i;
36 uint32_t uf;
37 uint32_t f;
38 double ff;
39
40 i = GET_BE_U_4(lfp->int_part);
41 uf = GET_BE_U_4(lfp->fraction);
42 ff = uf;
43 if (ff < 0.0) /* some compilers are buggy */
44 ff += FMAXINT;
45 ff = ff / FMAXINT; /* shift radix point by 32 bits */
46 f = (uint32_t)(ff * 1000000000.0); /* treat fraction as parts per billion */
47 ND_PRINT("%u.%09u", i, f);
48
49 /*
50 * print the UTC time in human-readable format.
51 */
52 if (i) {
53 int64_t seconds_64bit = (int64_t)i - JAN_1970;
54 time_t seconds;
55 char time_buf[128];
56 const char *time_string;
57
58 seconds = (time_t)seconds_64bit;
59 if (seconds != seconds_64bit) {
60 /*
61 * It doesn't fit into a time_t, so we can't hand it
62 * to gmtime.
63 */
64 time_string = "[Time is too large to fit into a time_t]";
65 } else {
66 /* use ISO 8601 (RFC3339) format */
67 time_string = nd_format_time(time_buf, sizeof (time_buf),
68 "%Y-%m-%dT%H:%M:%SZ", gmtime(&seconds));
69 }
70 ND_PRINT(" (%s)", time_string);
71 }
72 }
73