Replace hand-rolled date printing/parsing code with strftime()/strptime().

Use timegm() because all the dates are in UTC and the 'standard'
routines can't handle the truth.

Remove some 'time_t is 32bits' assumptions.

Print 'UTC' at the end of dates in the leases file, rather than
mentioning that all dates are UTC in a comment at the top of the
file.

Feedback and suggestions from guenther@, kettenis@, otto@, tedu@,
deraadt@.

3 files changed, 62 insertions, 166 deletions

diff --git a/usr.sbin/dhcpd/db.c b/usr.sbin/dhcpd/db.c
index 8e3887e7ace..3f0df99eea6 100644
--- a/usr.sbin/dhcpd/db.c
+++ b/usr.sbin/dhcpd/db.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: db.c,v 1.11 2013/04/13 16:40:36 krw Exp $	*/
+/*	$OpenBSD: db.c,v 1.12 2013/04/17 19:26:10 krw Exp $	*/
 
 /*
  * Persistent database management routines for DHCPD.
@@ -56,8 +56,8 @@ time_t write_time;
 int
 write_lease(struct lease *lease)
 {
-	struct tm *t;
-	char tbuf[64];
+	char tbuf[26];	/* "w yyyy/mm/dd hh:mm:ss UTC" */
+	size_t rsltsz;
 	int errors = 0;
 	int i;
 
@@ -66,21 +66,15 @@ write_lease(struct lease *lease)
 	if (fprintf(db_file, "lease %s {\n", piaddr(lease->ip_addr)) == -1)
 		++errors;
 
-	t = gmtime(&lease->starts);
-	snprintf(tbuf, sizeof(tbuf), "%d %d/%02d/%02d %02d:%02d:%02d;",
-	    t->tm_wday, t->tm_year + 1900, t->tm_mon + 1, t->tm_mday,
-	    t->tm_hour, t->tm_min, t->tm_sec);
+	rsltsz = strftime(tbuf, sizeof(tbuf), DB_TIMEFMT,
+	    gmtime(&lease->starts));
+	if (rsltsz == 0 || fprintf(db_file, "\tstarts %s;\n", tbuf) == -1)
+		errors++;
 
-	if (fprintf(db_file, "\tstarts %s\n", tbuf) == -1)
-		++errors;
-
-	t = gmtime(&lease->ends);
-	snprintf(tbuf, sizeof(tbuf), "%d %d/%02d/%02d %02d:%02d:%02d;",
-	    t->tm_wday, t->tm_year + 1900, t->tm_mon + 1, t->tm_mday,
-	    t->tm_hour, t->tm_min, t->tm_sec);
-
-	if (fprintf(db_file, "\tends %s", tbuf) == -1)
-		++errors;
+	rsltsz = strftime(tbuf, sizeof(tbuf), DB_TIMEFMT,
+	    gmtime(&lease->ends));
+	if (rsltsz == 0 || fprintf(db_file, "\tends %s;\n", tbuf) == -1)
+		errors++;
 
 	if (lease->hardware_addr.hlen) {
 		if (fprintf(db_file, "\n\thardware %s %s;",
@@ -206,14 +200,6 @@ new_lease_file(void)
 	fflush(db_file);
 	rewind(db_file);
 
-	/*
-	 * Write an introduction so people don't complain about time being off.
-	 */
-	fprintf(db_file, "# All times in this file are in UTC (GMT), "
-	    "not your local timezone.\n");
-	fprintf(db_file, "# The format of this file is documented in "
-	    "the dhcpd.leases(5) manual page.\n\n");
-
 	/* Write out all the leases that we know of... */
 	counting = 0;
 	write_leases();
diff --git a/usr.sbin/dhcpd/dhcpd.h b/usr.sbin/dhcpd/dhcpd.h
index 125e71fbfb2..9c13aa803d8 100644
--- a/usr.sbin/dhcpd/dhcpd.h
+++ b/usr.sbin/dhcpd/dhcpd.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dhcpd.h,v 1.46 2013/02/03 21:04:19 krw Exp $ */
+/*	$OpenBSD: dhcpd.h,v 1.47 2013/04/17 19:26:10 krw Exp $ */
 
 /*
  * Copyright (c) 1995, 1996, 1997, 1998, 1999
@@ -74,6 +74,9 @@
 #include "dhcp.h"
 #include "tree.h"
 
+#define DB_TIMEFMT	"%w %Y/%m/%d %T UTC"
+#define OLD_DB_TIMEFMT	"%w %Y/%m/%d %T"
+
 #define SERVER_PORT	67
 #define CLIENT_PORT	68
 
diff --git a/usr.sbin/dhcpd/parse.c b/usr.sbin/dhcpd/parse.c
index b7c5159d37b..060927dbb54 100644
--- a/usr.sbin/dhcpd/parse.c
+++ b/usr.sbin/dhcpd/parse.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: parse.c,v 1.13 2010/03/27 14:11:38 krw Exp $	*/
+/*	$OpenBSD: parse.c,v 1.14 2013/04/17 19:26:10 krw Exp $	*/
 
 /* Common parser code for dhcpd and dhclient. */
 
@@ -259,6 +259,7 @@ void
 parse_lease_time(FILE *cfile, time_t *timep)
 {
 	char *val;
+	uint32_t value;
 	int token;
 
 	token = next_token(&val, cfile);
@@ -267,9 +268,9 @@ parse_lease_time(FILE *cfile, time_t *timep)
 		skip_to_semi(cfile);
 		return;
 	}
-	convert_num((unsigned char *)timep, val, 10, 32);
+	convert_num((unsigned char *)&value, val, 10, 32);
 	/* Unswap the number - convert_num returns stuff in NBO. */
-	*timep = ntohl(*timep);	/* XXX */
+	*timep = ntohl(value);	/* XXX */
 
 	parse_semi(cfile);
 }
@@ -465,160 +466,66 @@ convert_num(unsigned char *buf, char *str, int base, int size)
 
 /*
  * date :== NUMBER NUMBER SLASH NUMBER SLASH NUMBER
- *		NUMBER COLON NUMBER COLON NUMBER SEMI
+ *		NUMBER COLON NUMBER COLON NUMBER UTC SEMI
  *
- * Dates are always in GMT; first number is day of week; next is
+ * Dates are always in UTC; first number is day of week; next is
  * year/month/day; next is hours:minutes:seconds on a 24-hour
  * clock.
  */
 time_t
 parse_date(FILE *cfile)
 {
-	static int months[11] = { 31, 59, 90, 120, 151, 181,
-	    212, 243, 273, 304, 334 };
-	int guess, token;
 	struct tm tm;
-	char *val;
-
-	/* Day of week... */
-	token = next_token(&val, cfile);
-	if (token != TOK_NUMBER) {
-		parse_warn("numeric day of week expected.");
-		if (token != ';')
-			skip_to_semi(cfile);
-		return (0);
-	}
-	tm.tm_wday = atoi(val);
-
-	/* Year... */
-	token = next_token(&val, cfile);
-	if (token != TOK_NUMBER) {
-		parse_warn("numeric year expected.");
-		if (token != ';')
-			skip_to_semi(cfile);
-		return (0);
-	}
-	tm.tm_year = atoi(val);
-	if (tm.tm_year > 1900)
-		tm.tm_year -= 1900;
-
-	/* Slash separating year from month... */
-	token = next_token(&val, cfile);
-	if (token != '/') {
-		parse_warn("expected slash separating year from month.");
-		if (token != ';')
-			skip_to_semi(cfile);
-		return (0);
-	}
-
-	/* Month... */
-	token = next_token(&val, cfile);
-	if (token != TOK_NUMBER) {
-		parse_warn("numeric month expected.");
-		if (token != ';')
-			skip_to_semi(cfile);
-		return (0);
-	}
-	tm.tm_mon = atoi(val) - 1;
-
-	/* Slash separating month from day... */
-	token = next_token(&val, cfile);
-	if (token != '/') {
-		parse_warn("expected slash separating month from day.");
-		if (token != ';')
-			skip_to_semi(cfile);
-		return (0);
-	}
-
-	/* Day... */
-	token = next_token(&val, cfile);
-	if (token != TOK_NUMBER) {
-		parse_warn("numeric day of month expected.");
-		if (token != ';')
-			skip_to_semi(cfile);
-		return (0);
-	}
-	tm.tm_mday = atoi(val);
-
-	/* Hour... */
-	token = next_token(&val, cfile);
-	if (token != TOK_NUMBER) {
-		parse_warn("numeric hour expected.");
-		if (token != ';')
-			skip_to_semi(cfile);
-		return (0);
-	}
-	tm.tm_hour = atoi(val);
+	char timestr[26]; /* "w yyyy/mm/dd hh:mm:ss UTC" */
+	char *val, *p;
+	size_t n;
+	time_t guess;
+	int token;
 
-	/* Colon separating hour from minute... */
-	token = next_token(&val, cfile);
-	if (token != ':') {
-		parse_warn("expected colon separating hour from minute.");
-		if (token != ';')
-			skip_to_semi(cfile);
-		return (0);
-	}
+	memset(timestr, 0, sizeof(timestr));
 
-	/* Minute... */
-	token = next_token(&val, cfile);
-	if (token != TOK_NUMBER) {
-		parse_warn("numeric minute expected.");
-		if (token != ';')
+	do {
+		token = peek_token(NULL, cfile);
+		switch (token) {
+		case TOK_NAME:
+		case TOK_NUMBER:
+		case '/':
+		case ':':
+			token = next_token(&val, cfile);
+			n = strlcat(timestr, val, sizeof(timestr));
+			if (n >= sizeof(timestr)) {
+				/* XXX Will break after year 9999! */
+				parse_warn("time string too long");
+				skip_to_semi(cfile);
+				return (0);
+			}
+			break;
+		case';':
+			break;
+		default:
+			parse_warn("invalid time string");
 			skip_to_semi(cfile);
-		return (0);
-	}
-	tm.tm_min = atoi(val);
+			return (0);
+		}
+	} while (token != ';');
 
-	/* Colon separating minute from second... */
-	token = next_token(&val, cfile);
-	if (token != ':') {
-		parse_warn("expected colon separating minute from second.");
-		if (token != ';')
-			skip_to_semi(cfile);
-		return (0);
-	}
+	parse_semi(cfile);
 
-	/* Second... */
-	token = next_token(&val, cfile);
-	if (token != TOK_NUMBER) {
-		parse_warn("numeric second expected.");
-		if (token != ';')
-			skip_to_semi(cfile);
-		return (0);
+	memset(&tm, 0, sizeof(tm));	/* 'cuz strptime ignores tm_isdt. */
+	p = strptime(timestr, DB_TIMEFMT, &tm);
+	if (p == NULL || *p != '\0') {
+		p = strptime(timestr, OLD_DB_TIMEFMT, &tm);
+		if (p == NULL || *p != '\0') {
+			parse_warn("unparseable time string");
+			return (0);
+		}
 	}
-	tm.tm_sec = atoi(val);
-	tm.tm_isdst = 0;
-
-	/* XXX: We assume that mktime does not use tm_yday. */
-	tm.tm_yday = 0;
 
-	/* Make sure the date ends in a semicolon... */
-	token = next_token(&val, cfile);
-	if (token != ';') {
-		parse_warn("semicolon expected.");
-		skip_to_semi(cfile);
+	guess = timegm(&tm);
+	if (guess == -1) {
+		parse_warn("time could not be represented");
 		return (0);
 	}
 
-	/* Guess the time value... */
-	guess = ((((((365 * (tm.tm_year - 70) +	/* Days in years since '70 */
-	    (tm.tm_year - 69) / 4 +	/* Leap days since '70 */
-	    (tm.tm_mon			/* Days in months this year */
-	    ? months[tm.tm_mon - 1] : 0) +
-	    (tm.tm_mon > 1 &&		/* Leap day this year */
-	    !((tm.tm_year - 72) & 3)) +
-	    tm.tm_mday - 1) * 24) +	/* Day of month */
-	    tm.tm_hour) * 60) + tm.tm_min) * 60) + tm.tm_sec;
-
-	/*
-	 * This guess could be wrong because of leap seconds or other
-	 * weirdness we don't know about that the system does.   For
-	 * now, we're just going to accept the guess, but at some point
-	 * it might be nice to do a successive approximation here to get
-	 * an exact value.   Even if the error is small, if the server
-	 * is restarted frequently (and thus the lease database is
-	 * reread), the error could accumulate into something
-	 * significant.
-	 */
 	return (guess);
 }