usyslogd: minor header restructuring/file structure cleanup

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

1 files changed, 285 insertions, 0 deletions

diff --git a/syslogd/syslogd.c b/syslogd/syslogd.c
new file mode 100644
index 0000000..03f4b55
--- /dev/null
+++ b/syslogd/syslogd.c
@@ -0,0 +1,285 @@
+/* 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 <getopt.h>
+#include <errno.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <pwd.h>
+#include <grp.h>
+
+#include "syslogd.h"
+#include "util.h"
+
+
+#define GPL_URL "https://gnu.org/licenses/gpl.html"
+
+
+static const struct option long_opts[] = {
+	{ "help", no_argument, NULL, 'h' },
+	{ "version", no_argument, NULL, 'V' },
+	{ "rotate-replace", no_argument, NULL, 'r' },
+	{ "max-size", required_argument, NULL, 'm' },
+	{ "user", required_argument, NULL, 'u' },
+	{ "group", required_argument, NULL, 'g' },
+	{ "chroot", required_argument, NULL, 'c' },
+	{ NULL, 0, NULL, 0 },
+};
+
+const char *short_opts = "hVrm:";
+
+const char *version_string =
+"usyslogd (pygos init) " PACKAGE_VERSION "\n"
+"Copyright (C) 2018 David Oberhollenzer\n\n"
+"License GPLv3+: GNU GPL version 3 or later <" GPL_URL ">.\n"
+"This is free software: you are free to change and redistribute it.\n"
+"There is NO WARRANTY, to the extent permitted by law.\n";
+
+const char *usage_string =
+"Usage: usyslogd [OPTIONS..]\n\n"
+"The following options are supported:\n"
+"  -h, --help             Print this help text and exit\n"
+"  -V, --version          Print version information and exit\n"
+"  -r, --rotate-replace   Replace old log files when doing log rotation.\n"
+"  -m, --max-size <size>  Automatically rotate log files bigger than this.\n"
+"  -u, --user <name>      Run the syslog daemon as this user. If not set,\n"
+"                         try to use the user '" DEFAULT_USER "'.\n"
+"  -g, --group <name>     Run the syslog daemon as this group. If not set,\n"
+"                         try to use the group '" DEFAULT_GROUP "'.\n"
+"  -c, --chroot           If set, do a chroot into the log file path.\n";
+
+
+
+static volatile sig_atomic_t syslog_run = 1;
+static volatile sig_atomic_t syslog_rotate = 0;
+static int log_flags = 0;
+static size_t max_size = 0;
+static uid_t uid = 0;
+static gid_t gid = 0;
+static bool dochroot = false;
+
+
+
+static void sighandler(int signo)
+{
+	switch (signo) {
+	case SIGINT:
+	case SIGTERM:
+		syslog_run = 0;
+		break;
+	case SIGHUP:
+		syslog_rotate = 1;
+		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);
+	sigaction(SIGHUP, &act, NULL);
+}
+
+static int handle_data(int fd)
+{
+	char buffer[2048];
+	syslog_msg_t msg;
+	ssize_t ret;
+
+	memset(buffer, 0, sizeof(buffer));
+
+	ret = read(fd, buffer, sizeof(buffer));
+	if (ret <= 0)
+		return -1;
+
+	if (syslog_msg_parse(&msg, buffer))
+		return -1;
+
+	return logmgr->write(logmgr, &msg);
+}
+
+static void process_options(int argc, char **argv)
+{
+	struct passwd *pw = getpwnam(DEFAULT_USER);
+	struct group *grp = getgrnam(DEFAULT_GROUP);
+	char *end;
+	int i;
+
+	if (pw != NULL)
+		uid = pw->pw_uid;
+
+	if (grp != NULL)
+		gid = grp->gr_gid;
+
+	for (;;) {
+		i = getopt_long(argc, argv, short_opts, long_opts, NULL);
+		if (i == -1)
+			break;
+
+		switch (i) {
+		case 'r':
+			log_flags |= LOG_ROTATE_OVERWRITE;
+			break;
+		case 'm':
+			log_flags |= LOG_ROTATE_SIZE_LIMIT;
+			max_size = strtol(optarg, &end, 10);
+			if (max_size == 0 || *end != '\0') {
+				fputs("Numeric argument > 0 expected for -m\n",
+				      stderr);
+				goto fail;
+			}
+			break;
+		case 'u':
+			pw = getpwnam(optarg);
+			if (pw == NULL) {
+				fprintf(stderr, "Cannot get UID for user %s\n",
+					optarg);
+				goto fail;
+			}
+			uid = pw->pw_uid;
+			break;
+		case 'g':
+			grp = getgrnam(optarg);
+			if (grp == NULL) {
+				fprintf(stderr,
+					"Cannot get GID for group %s\n",
+					optarg);
+				goto fail;
+			}
+			gid = grp->gr_gid;
+			break;
+		case 'c':
+			dochroot = true;
+			break;
+		case 'h':
+			fputs(usage_string, stdout);
+			exit(EXIT_SUCCESS);
+		case 'V':
+			fputs(version_string, stdout);
+			exit(EXIT_SUCCESS);
+		default:
+			goto fail;
+		}
+	}
+	return;
+fail:
+	fputs("Try `usyslogd --help' for more information\n", stderr);
+	exit(EXIT_FAILURE);
+}
+
+static int chroot_setup(void)
+{
+	if (mkdir(SYSLOG_PATH, 0750)) {
+		if (errno != EEXIST) {
+			perror("mkdir " SYSLOG_PATH);
+			return -1;
+		}
+	}
+
+	if (uid > 0 && gid > 0 && chown(SYSLOG_PATH, uid, gid) != 0) {
+		perror("chown " SYSLOG_PATH);
+		return -1;
+	}
+
+	if (chmod(SYSLOG_PATH, 0750)) {
+		perror("chmod " SYSLOG_PATH);
+		return -1;
+	}
+
+	if (chdir(SYSLOG_PATH)) {
+		perror("cd " SYSLOG_PATH);
+		return -1;
+	}
+
+	if (dochroot && chroot(SYSLOG_PATH) != 0) {
+		perror("chroot " SYSLOG_PATH);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int user_setup(void)
+{
+	if (gid > 0 && setresgid(gid, gid, gid) != 0) {
+		perror("setgid");
+		return -1;
+	}
+	if (uid > 0 && setresuid(uid, uid, uid) != 0) {
+		perror("setuid");
+		return -1;
+	}
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	int sfd, status = EXIT_FAILURE;
+
+	process_options(argc, argv);
+
+	signal_setup();
+
+	sfd = mksock(SYSLOG_SOCKET, SOCK_FLAG_EVERYONE | SOCK_FLAG_DGRAM);
+	if (sfd < 0)
+		return EXIT_FAILURE;
+
+	if (uid > 0 && gid > 0 && chown(SYSLOG_SOCKET, uid, gid) != 0) {
+		perror("chown " SYSLOG_SOCKET);
+		return -1;
+	}
+
+	if (chroot_setup())
+		return EXIT_FAILURE;
+
+	if (user_setup())
+		return EXIT_FAILURE;
+
+	if (logmgr->init(logmgr, log_flags, max_size))
+		goto out;
+
+	while (syslog_run) {
+		if (syslog_rotate) {
+			logmgr->rotate(logmgr);
+			syslog_rotate = 0;
+		}
+
+		handle_data(sfd);
+	}
+
+	status = EXIT_SUCCESS;
+out:
+	logmgr->cleanup(logmgr);
+	if (sfd > 0)
+		close(sfd);
+	unlink(SYSLOG_SOCKET);
+	return status;
+}