Fix local time printing

Using seconds offset from GMT to local time to compute local time give
errors when printing times outside the same daylight saving time period.

Use the localtime() function for default and -tttt cases.
Use the gmtime() function for -ttt and -ttttt cases.

Rename ts_hmsfrac_print() to ts_date_hmsfrac_print().
Remove some variables now useless.
Update some comments.

1 files changed, 40 insertions, 29 deletions

diff --git a/util-print.c b/util-print.c
index 7f23a4b0..06844898 100644
--- a/util-print.c
+++ b/util-print.c
@@ -57,12 +57,15 @@
 #include "ascii_strcasecmp.h"
 #include "timeval-operations.h"
 
-int32_t thiszone;		/* seconds offset from gmt to local time */
 /* invalid string to print '(invalid)' for malformed or corrupted packets */
 const char istr[] = " (invalid)";
 
 #define TOKBUFSIZE 128
 
+
+enum date_flag { WITHOUT_DATE = 0, WITH_DATE = 1 };
+enum time_flag { UTC_TIME = 0, LOCAL_TIME = 1 };
+
 /*
  * Print out a character, filtering out the non-printable ones
  */
@@ -229,32 +232,50 @@ nd_printzp(netdissect_options *ndo,
 }
 
 /*
- * Print the timestamp as HH:MM:SS.FRAC.
+ * Print the timestamp as [YY:MM:DD] HH:MM:SS.FRAC.
+ *   if time_flag == LOCAL_TIME print local time else UTC/GMT time
+ *   if date_flag == WITH_DATE print YY:MM:DD before HH:MM:SS.FRAC
  */
 static void
-ts_hmsfrac_print(netdissect_options *ndo, int sec, int usec)
+ts_date_hmsfrac_print(netdissect_options *ndo, int sec, int usec,
+		      enum date_flag date_flag, enum time_flag time_flag)
 {
+	time_t Time = sec;
+	struct tm *tm;
+	char timestr[32];
+
+	if (time_flag == LOCAL_TIME)
+		tm = localtime(&Time);
+	else
+		tm = gmtime(&Time);
+
+	if (!tm) {
+		ND_PRINT("[Error converting time]");
+		return;
+	}
+	if (date_flag == WITH_DATE)
+		strftime(timestr, sizeof(timestr), "%Y-%m-%d %H:%M:%S", tm);
+	else
+		strftime(timestr, sizeof(timestr), "%H:%M:%S", tm);
+	ND_PRINT("%s", timestr);
+
 #ifdef HAVE_PCAP_SET_TSTAMP_PRECISION
 	switch (ndo->ndo_tstamp_precision) {
 
 	case PCAP_TSTAMP_PRECISION_MICRO:
-		ND_PRINT("%02d:%02d:%02d.%06u", sec / 3600, (sec % 3600) / 60,
-		    sec % 60, usec);
+		ND_PRINT(".%06u", usec);
 		break;
 
 	case PCAP_TSTAMP_PRECISION_NANO:
-		ND_PRINT("%02d:%02d:%02d.%09u", sec / 3600, (sec % 3600) / 60,
-		    sec % 60, usec);
+		ND_PRINT(".%09u", usec);
 		break;
 
 	default:
-		ND_PRINT("%02d:%02d:%02d.{unknown}", sec / 3600, (sec % 3600) / 60,
-		    sec % 60);
+		ND_PRINT(".{unknown}");
 		break;
 	}
 #else
-	ND_PRINT("%02d:%02d:%02d.%06u", sec / 3600, (sec % 3600) / 60,
-	    sec % 60, usec);
+	ND_PRINT(".%06u", usec);
 #endif
 }
 
@@ -291,9 +312,6 @@ void
 ts_print(netdissect_options *ndo,
          const struct timeval *tvp)
 {
-	int s;
-	struct tm *tm;
-	time_t Time;
 	static struct timeval tv_ref;
 	struct timeval tv_result;
 	int negative_offset;
@@ -302,8 +320,8 @@ ts_print(netdissect_options *ndo,
 	switch (ndo->ndo_tflag) {
 
 	case 0: /* Default */
-		s = (tvp->tv_sec + thiszone) % 86400;
-		ts_hmsfrac_print(ndo, s, tvp->tv_usec);
+		ts_date_hmsfrac_print(ndo, tvp->tv_sec, tvp->tv_usec,
+				      WITHOUT_DATE, LOCAL_TIME);
 		ND_PRINT(" ");
 		break;
 
@@ -342,25 +360,18 @@ ts_print(netdissect_options *ndo,
 			netdissect_timevalsub(tvp, &tv_ref, &tv_result, nano_prec);
 
 		ND_PRINT((negative_offset ? "-" : " "));
-		ts_hmsfrac_print(ndo, tv_result.tv_sec, tv_result.tv_usec);
+		ts_date_hmsfrac_print(ndo, tv_result.tv_sec, tv_result.tv_usec,
+				      WITHOUT_DATE, UTC_TIME);
 		ND_PRINT(" ");
 
                 if (ndo->ndo_tflag == 3)
 			tv_ref = *tvp; /* set timestamp for previous packet */
 		break;
 
-	case 4: /* Default + Date */
-		s = (tvp->tv_sec + thiszone) % 86400;
-		Time = (tvp->tv_sec + thiszone) - s;
-		tm = gmtime (&Time);
-		if (!tm)
-			ND_PRINT("Date fail ");
-		else {
-			ND_PRINT("%04d-%02d-%02d ",
-			    tm->tm_year+1900, tm->tm_mon+1, tm->tm_mday);
-			ts_hmsfrac_print(ndo, s, tvp->tv_usec);
-			ND_PRINT(" ");
-		}
+	case 4: /* Date + Default */
+		ts_date_hmsfrac_print(ndo, tvp->tv_sec, tvp->tv_usec,
+				      WITH_DATE, LOCAL_TIME);
+		ND_PRINT(" ");
 		break;
 	}
 }