diff options
author | Guy Harris <gharris@sonic.net> | 2024-03-28 22:45:47 -0700 |
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committer | Guy Harris <gharris@sonic.net> | 2024-03-28 22:45:47 -0700 |
commit | 433405d2a026af01382a5a0ad943b10180068161 (patch) | |
tree | 1767e3e85ef3a7e5c54cb90f217d39016abf47a5 | |
parent | cf3566e677bd30beacbf997ca3afff1ff4831947 (diff) | |
download | tcpdump-433405d2a026af01382a5a0ad943b10180068161.tar.gz |
SMB: clean up date handling.
Pull the routine that carves a DOS date/time up and puts it into a
struct tm into the routine that converts the struct tm into a time_t.
Note a place where a DOS date/time might not fit in a 32-bit integral
time_t (DOS dates and times can go past the Y2.038K date/time).
Do the NT FILETIME to time_t conversion as an all-integer operation.
Catch cases where the result doesn't fit into a time_t. (And rename the
routine to speak of it as a FILETIME; that's what it's called.)
-rw-r--r-- | smbutil.c | 100 |
1 files changed, 51 insertions, 49 deletions
@@ -35,43 +35,38 @@ smb_reset(void) } /* - * interpret a 32 bit dos packed date/time to some parameters - */ -static void -interpret_dos_date(uint32_t date, struct tm *tp) -{ - uint32_t p0, p1, p2, p3; - - p0 = date & 0xFF; - p1 = ((date & 0xFF00) >> 8) & 0xFF; - p2 = ((date & 0xFF0000) >> 16) & 0xFF; - p3 = ((date & 0xFF000000) >> 24) & 0xFF; - - tp->tm_sec = 2 * (p0 & 0x1F); - tp->tm_min = ((p0 >> 5) & 0xFF) + ((p1 & 0x7) << 3); - tp->tm_hour = (p1 >> 3) & 0xFF; - tp->tm_mday = (p2 & 0x1F); - tp->tm_mon = ((p2 >> 5) & 0xFF) + ((p3 & 0x1) << 3) - 1; - tp->tm_year = ((p3 >> 1) & 0xFF) + 80; -} - -/* - * common portion: - * create a unix date from a dos date + * create a UNIX time_t from a 32-bit DOS packetd date/time, with + * the DOS date/time assumed to be local time in *our* location. */ static time_t int_unix_date(uint32_t dos_date) { + uint32_t p0, p1, p2, p3; struct tm t; if (dos_date == 0) return(0); - interpret_dos_date(dos_date, &t); - t.tm_wday = 1; - t.tm_yday = 1; - t.tm_isdst = 0; - + p0 = dos_date & 0xFF; + p1 = ((dos_date & 0xFF00) >> 8) & 0xFF; + p2 = ((dos_date & 0xFF0000) >> 16) & 0xFF; + p3 = ((dos_date & 0xFF000000) >> 24) & 0xFF; + + t.tm_sec = 2 * (p0 & 0x1F); + t.tm_min = ((p0 >> 5) & 0xFF) + ((p1 & 0x7) << 3); + t.tm_hour = (p1 >> 3) & 0xFF; + t.tm_mday = (p2 & 0x1F); + t.tm_mon = ((p2 >> 5) & 0xFF) + ((p3 & 0x1) << 3) - 1; + t.tm_year = ((p3 >> 1) & 0xFF) + 80; + + t.tm_wday = 1; /* XXX - should not affect the result; why 1? */ + t.tm_yday = 1; /* XXX - should not affect the result; why 1? */ + t.tm_isdst = 0; /* XXX - should be -1, to handle DST? */ + + /* + * XXX - if tm_year is 2038 or later, this might not fit in a + * 32-bit time_t. + */ return (mktime(&t)); } @@ -103,31 +98,38 @@ make_unix_date2(netdissect_options *ndo, const u_char *date_ptr) return int_unix_date(x2); } +/* Delta between the NT FILETIME epoch and the POSIX epoch. */ +#define FILETIME_TO_POSIX_DELTA INT64_C(11644473600) + /* - * interpret an 8 byte "filetime" structure to a time_t + * interpret an 8 byte NT FILETIME structure to a time_t * It's originally in "100ns units since jan 1st 1601" */ static time_t -interpret_long_date(netdissect_options *ndo, const u_char *p) +interpret_filetime(netdissect_options *ndo, const u_char *p) { - double d; - time_t ret; - - /* this gives us seconds since jan 1st 1601 (approx) */ - d = (GET_LE_U_4(p + 4) * 256.0 + GET_U_1(p + 3)) * (1.0e-7 * (1 << 24)); - - /* now adjust by 369 years to make the secs since 1970 */ - d -= 369.0 * 365.25 * 24 * 60 * 60; - - /* and a fudge factor as we got it wrong by a few days */ - d += (3 * 24 * 60 * 60 + 6 * 60 * 60 + 2); - - if (d < 0) - return(0); - - ret = (time_t)d; - - return(ret); + int64_t ret; + time_t ret_time_t; + + /* + * Fetch a FILETIME structure; the first 4 bytes are the low-order + * 32 bits of a 64-bit count of 100ns units since 1601-01-01 + * at some specific time, and the next 4 bytes are the high-order + * 32 bits of that count. + */ + ret = (int64_t)(((uint64_t)GET_LE_U_4(p + 4) << 32) + (uint64_t)GET_LE_U_4(p)); + + /* Now convert from FILETIME to POSIX time. */ + ret += FILETIME_TO_POSIX_DELTA; + + ret_time_t = (time_t)ret; + if (ret_time_t != ret) { + /* + * It doesn't fit in a time_t. Return 0, as an error indication. + */ + return(0); + } + return(ret_time_t); } /* @@ -790,7 +792,7 @@ smb_fdata1(netdissect_options *ndo, break; case 3: ND_TCHECK_8(buf); - t = interpret_long_date(ndo, buf); + t = interpret_filetime(ndo, buf); buf += 8; break; default: |