[usyslogd] split off syslog parsing

 - Add proto.{h,c} for parsing of syslog message
 - Also parse time stamp in addition to priority

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>

1 files changed, 177 insertions, 0 deletions

diff --git a/syslogd/proto.c b/syslogd/proto.c
new file mode 100644
index 0000000..3487dbd
--- /dev/null
+++ b/syslogd/proto.c
@@ -0,0 +1,177 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * Copyright (C) 2018 - David Oberhollenzer
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+#include <stddef.h>
+#include <string.h>
+#include <ctype.h>
+#include <time.h>
+
+#include "proto.h"
+
+static const char *months[] = {
+	"Jan", "Feb", "Mar", "Apr",
+	"May", "Jun", "Jul", "Aug",
+	"Sep", "Oct", "Nov", "Dec"
+};
+
+static const int days[12] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
+
+static int isleap(int year)
+{
+	return ((year % 4 == 0) && (year % 100 != 0)) || ((year % 400) == 0);
+}
+
+static int mdays(int year, int month)
+{
+	return (isleap(year) && month == 2) ? 29 : days[month - 1];
+}
+
+static char *read_num(char *str, int *out, int maxval)
+{
+	if (str == NULL || !isdigit(*str))
+		return NULL;
+	for (*out = 0; isdigit(*str); ++str) {
+		(*out) = (*out) * 10 + (*str) - '0';
+		if ((*out) > maxval)
+			return NULL;
+	}
+	return str;
+}
+
+static char *skip_space(char *str)
+{
+	if (str == NULL || !isspace(*str))
+		return NULL;
+	while (isspace(*str))
+		++str;
+	return str;
+}
+
+static char *read_date_bsd(char *str, struct tm *tm)
+{
+	int year, month, day, hour, minute, second;
+	time_t t;
+
+	/* decode date */
+	for (month = 0; month < 12; ++month) {
+		if (strncmp(str, months[month], 3) == 0) {
+			str = skip_space(str + 3);
+			break;
+		}
+	}
+
+	str = read_num(str, &day, 31);
+	str = skip_space(str);
+
+	t = time(NULL);
+	if (localtime_r(&t, tm) == NULL)
+		return NULL;
+
+	year = tm->tm_year;
+
+	/* sanity check */
+	if (str == NULL || month >= 12 || day < 1)
+		return NULL;
+	if (month == 11 && tm->tm_mon == 0)
+		--year;
+	if (day > mdays(year + 1900, month + 1))
+		return NULL;
+
+	/* decode time */
+	str = read_num(str, &hour, 23);
+	if (str == NULL || *(str++) != ':')
+		return NULL;
+	str = read_num(str, &minute, 59);
+	if (str == NULL || *(str++) != ':')
+		return NULL;
+	str = read_num(str, &second, 59);
+	str = skip_space(str);
+
+	/* store result */
+	memset(tm, 0, sizeof(*tm));
+	tm->tm_sec = second;
+	tm->tm_min = minute;
+	tm->tm_hour = hour;
+	tm->tm_mday = day;
+	tm->tm_mon = month;
+	tm->tm_year = year;
+	return str;
+}
+
+static char *decode_priority(char *str, int *priority)
+{
+	while (isspace(*str))
+		++str;
+	if (*(str++) != '<')
+		return NULL;
+	str = read_num(str, priority, 23 * 8 + 7);
+	if (str == NULL || *(str++) != '>')
+		return NULL;
+	while (isspace(*str))
+		++str;
+	return str;
+}
+
+int syslog_msg_parse(syslog_msg_t *msg, char *str)
+{
+	char *ident, *ptr;
+	struct tm tstamp;
+	pid_t pid = 0;
+	int priority;
+
+	memset(msg, 0, sizeof(*msg));
+
+	str = decode_priority(str, &priority);
+	if (str == NULL)
+		return -1;
+
+	msg->facility = priority >> 3;
+	msg->level = priority & 0x07;
+
+	str = read_date_bsd(str, &tstamp);
+	if (str == NULL)
+		return -1;
+
+	ident = str;
+	while (*str != '\0' && *str != ':')
+		++str;
+
+	if (*str == ':') {
+		*(str++) = '\0';
+		while (isspace(*str))
+			++str;
+
+		ptr = ident;
+		while (*ptr != '[' && *ptr != '\0')
+			++ptr;
+
+		if (*ptr == '[') {
+			*(ptr++) = '\0';
+
+			while (isdigit(*ptr))
+				pid = pid * 10 + *(ptr++) - '0';
+		}
+	} else {
+		ident = NULL;
+	}
+
+	msg->timestamp = mktime(&tstamp);
+	msg->pid = pid;
+	msg->ident = ident;
+	msg->message = str;
+	return 0;
+}