Add minimalistic syslog daemon

For now this daemon simply dumps all syslog messages into seperate log
files and doesn't do much parsing. Since the messages are readable ASCII
anyway, this should not be to much of a problem and sufficient for
debugging.

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

4 files changed, 320 insertions, 0 deletions

diff --git a/syslogd/Makemodule.am b/syslogd/Makemodule.am
new file mode 100644
index 0000000..489acc9
--- /dev/null
+++ b/syslogd/Makemodule.am
@@ -0,0 +1,8 @@
+usyslogd_SOURCES = syslogd/main.c
+usyslogd_SOURCES += syslogd/logfile.c syslogd/logfile.h
+usyslogd_CPPFLAGS = $(AM_CPPFLAGS)
+usyslogd_CFLAGS = $(AM_CFLAGS)
+usyslogd_LDFLAGS = $(AM_LDFLAGS)
+usyslogd_LDADD = libinit.a
+
+sbin_PROGRAMS += usyslogd
diff --git a/syslogd/logfile.c b/syslogd/logfile.c
new file mode 100644
index 0000000..a59f7e7
--- /dev/null
+++ b/syslogd/logfile.c
@@ -0,0 +1,69 @@
+/* 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 <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <fcntl.h>
+
+#include "logfile.h"
+
+
+logfile_t *logfile_create(const char *name)
+{
+	logfile_t *file;
+
+	file = calloc(1, sizeof(*file) + strlen(name) + 1);
+	if (file == NULL) {
+		perror("calloc");
+		return NULL;
+	}
+
+	strcpy(file->name, name);
+
+	file->fd = open(file->name, O_WRONLY | O_CREAT, 0640);
+	if (file->fd < 0)
+		goto fail;
+
+	if (lseek(file->fd, 0, SEEK_END))
+		goto fail;
+
+	return file;
+fail:
+	perror(file->name);
+	free(file);
+	return NULL;
+}
+
+void logfile_destroy(logfile_t *file)
+{
+	close(file->fd);
+	free(file);
+}
+
+void logfile_write(logfile_t *file, const char *format, ...)
+{
+	va_list ap;
+
+	va_start(ap, format);
+	vdprintf(file->fd, format, ap);
+	va_end(ap);
+
+	fsync(file->fd);
+}
diff --git a/syslogd/logfile.h b/syslogd/logfile.h
new file mode 100644
index 0000000..58da272
--- /dev/null
+++ b/syslogd/logfile.h
@@ -0,0 +1,34 @@
+/* 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/>.
+ */
+#ifndef LOGFILE_H
+#define LOGFILE_H
+
+typedef struct logfile_t {
+	struct logfile_t *next;
+	int fd;
+
+	char name[];
+} logfile_t;
+
+logfile_t *logfile_create(const char *name);
+
+void logfile_destroy(logfile_t *file);
+
+void logfile_write(logfile_t *file, const char *format, ...);
+
+#endif /* LOGFILE_H */
diff --git a/syslogd/main.c b/syslogd/main.c
new file mode 100644
index 0000000..a5702b7
--- /dev/null
+++ b/syslogd/main.c
@@ -0,0 +1,209 @@
+/* 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 <sys/types.h>
+#include <sys/stat.h>
+#include <sys/socket.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <string.h>
+#include <errno.h>
+#include <stdio.h>
+#include <ctype.h>
+
+#include "logfile.h"
+#include "util.h"
+
+
+#define SYSLOG_SOCKET "/dev/log"
+#define SYSLOG_PATH "/var/log"
+
+
+static volatile sig_atomic_t syslog_run = 1;
+static logfile_t *logfiles = NULL;
+
+static const enum_map_t facilities[] = {
+	{ "kernel.log", 0 },
+	{ "user.log", 1 },
+	{ "mail.log", 2 },
+	{ "daemon.log", 3 },
+	{ "auth.log", 4 },
+	{ "syslog.log", 5 },
+	{ "lpr.log", 6 },
+	{ "news.log", 7 },
+	{ "uucp.log", 8 },
+	{ "clock.log", 9 },
+	{ "authpriv.log", 10 },
+	{ "ftp.log", 11 },
+	{ "ntp.log", 12 },
+	{ "audit.log", 13 },
+	{ "alert.log", 14 },
+	{ "cron.log", 15 },
+	{ "local0.log", 16 },
+	{ "local1.log", 17 },
+	{ "local2.log", 18 },
+	{ "local3.log", 19 },
+	{ "local4.log", 20 },
+	{ "local5.log", 21 },
+	{ "local6.log", 22 },
+	{ "local7.log", 23 },
+	{ NULL, 0 },
+};
+
+static const enum_map_t levels[] = {
+	{ "emergency", 0 },
+	{ "alert", 1 },
+	{ "critical", 2 },
+	{ "error", 3 },
+	{ "warning", 4 },
+	{ "notice", 5 },
+	{ "info", 6 },
+	{ "debug", 7 },
+	{ NULL, 0 },
+};
+
+
+static int directory_setup(void)
+{
+	if (mkdir(SYSLOG_PATH, 0755)) {
+		if (errno != EEXIST) {
+			perror("mkdir " SYSLOG_PATH);
+			return -1;
+		}
+	}
+
+	if (chdir(SYSLOG_PATH)) {
+		perror("cd " SYSLOG_PATH);
+		return -1;
+	}
+
+	return 0;
+}
+
+static void sighandler(int signo)
+{
+	switch (signo) {
+	case SIGINT:
+	case SIGTERM:
+		syslog_run = 0;
+		break;
+	default:
+		break;
+	}
+}
+
+static void signal_setup(void)
+{
+	struct sigaction act;
+
+	memset(&act, 0, sizeof(act));
+	act.sa_handler = sighandler;
+
+	sigaction(SIGINT, &act, NULL);
+	sigaction(SIGTERM, &act, NULL);
+}
+
+static int print_to_log(int facility, int level, const char *data)
+{
+	const char *fac_name, *lvl_str;
+	logfile_t *log;
+
+	fac_name = enum_to_name(facilities, facility);
+	if (fac_name == NULL)
+		return -1;
+
+	lvl_str = enum_to_name(levels, level);
+	if (lvl_str == NULL)
+		return -1;
+
+	for (log = logfiles; log != NULL; log = log->next) {
+		if (!strcmp(log->name, fac_name))
+			break;
+	}
+
+	if (log == NULL) {
+		log = logfile_create(fac_name);
+		if (log == NULL)
+			return -1;
+		log->next = logfiles;
+		logfiles = log;
+	}
+
+	logfile_write(log, "[%s] %s", lvl_str, data);
+	return 0;
+}
+
+static int handle_data(int fd)
+{
+	char buffer[2048], *ptr;
+	int i = 0, priority;
+	ssize_t ret;
+
+	memset(buffer, 0, sizeof(buffer));
+
+	ret = read(fd, buffer, sizeof(buffer));
+	if (ret <= 0)
+		return -1;
+
+	for (ptr = buffer; isspace(*ptr); ++ptr)
+		;
+	if (*(ptr++) != '<')
+		return -1;
+	if (!isdigit(*ptr))
+		return -1;
+	for (priority = 0; isdigit(*ptr); ++ptr)
+		priority = priority * 10 + (*ptr) - '0';
+	if (*(ptr++) != '>')
+		return -1;
+	while (isspace(*ptr))
+		++ptr;
+
+	return print_to_log(priority >> 3, priority & 0x07, ptr);
+}
+
+int main(void)
+{
+	int sfd, status = EXIT_FAILURE;
+	logfile_t *log;
+
+	signal_setup();
+
+	sfd = mksock(SYSLOG_SOCKET, SOCK_FLAG_EVERYONE | SOCK_FLAG_DGRAM);
+	if (sfd < 0)
+		return EXIT_FAILURE;
+
+	if (directory_setup())
+		goto out;
+
+	while (syslog_run) {
+		handle_data(sfd);
+	}
+
+	status = EXIT_SUCCESS;
+out:
+	while (logfiles != NULL) {
+		log = logfiles;
+		logfiles = logfiles->next;
+
+		logfile_destroy(log);
+	}
+	if (sfd > 0)
+		close(sfd);
+	unlink(SYSLOG_SOCKET);
+	return status;
+}