- Add basic daemon and Makefile

Makefile

@@ -0,0 +1,14 @@
+PREFIX=/usr/local
+INC=-I$(PREFIX)/include
+LIB=-L$(PREFIX)/lib  -lutil
+FLAGS=-Wall -O2 -pipe -funroll-loops -ffast-math -fno-strict-aliasing
+CC?=cc
+
+all: fsipd
+
+fsipd: fsipd.c Makefile 
+	$(CC) $(FLAGS) $(INC) $(LIB) fsipd.c -o fsipd
+
+clean:
+	rm -f fsipd
+

fsipd.c

@@ -0,0 +1,170 @@
+/*-
+ * Copyright (c) 2015, Babak Farrokhi
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include <sys/cdefs.h>
+#include <sys/types.h>
+#include <sys/param.h>
+#include <sys/time.h>
+#include <sys/file.h>
+#include <sys/socket.h>
+#include <net/if.h>
+#include <net/if_var.h>
+#include <net/if_types.h>
+#include <ifaddrs.h>
+
+#include <err.h>
+#include <errno.h>
+
+#include <signal.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sysexits.h>
+#include <unistd.h>
+#include <libutil.h>
+
+/* Globals */
+struct pidfh *pfh;
+
+/*
+ * Prepare for a clean shutdown
+ */
+void 
+daemon_shutdown()
+{
+	pidfile_remove(pfh);
+}
+
+/*
+ * Act upon receiving signals
+ */
+void 
+signal_handler(int sig)
+{
+	switch (sig) {
+
+	case SIGHUP:
+	case SIGINT:
+	case SIGTERM:
+		daemon_shutdown();
+		exit(EXIT_SUCCESS);
+		break;
+	default:
+		break;
+	}
+}
+
+/*
+ * Daemonize and persist pid
+ */
+int 
+daemon_start()
+{
+	struct sigaction sig_action;
+	sigset_t sig_set;
+	pid_t otherpid;
+
+	char *no_fork = getenv("no_fork");
+
+	if (!no_fork || strcmp("1", no_fork)) {
+
+		/* Check if parent process id is set */
+		if (getppid() == 1) {
+			/* PPID exists, therefore we are already a daemon */
+			return (EXIT_FAILURE);
+		}
+		/* Check if we can acquire the pid file */
+		pfh = pidfile_open(NULL, 0600, &otherpid);
+
+		if (pfh == NULL) {
+			if (errno == EEXIST) {
+				errx(EXIT_FAILURE, "Daemon already running, pid: %jd.", (intmax_t)otherpid);
+			}
+			warn("Cannot open or create pidfile.");
+		}
+		/* fork ourselves if not asked otherwise */
+		if (fork()) {
+			return (EXIT_SUCCESS);
+		}
+		/* we are the child, complete the daemonization */
+
+		/* Close standard IO */
+		fclose(stdin);
+		fclose(stdout);
+		fclose(stderr);
+
+		/* Block unnecessary signals */
+		sigemptyset(&sig_set);
+		sigaddset(&sig_set, SIGCHLD);	/* ignore child - i.e. we
+						 * don't need to wait for it */
+		sigaddset(&sig_set, SIGTSTP);	/* ignore Tty stop signals */
+		sigaddset(&sig_set, SIGTTOU);	/* ignore Tty background
+						 * writes */
+		sigaddset(&sig_set, SIGTTIN);	/* ignore Tty background reads */
+		sigprocmask(SIG_BLOCK, &sig_set, NULL);	/* Block the above
+							 * specified signals */
+
+		/* Catch necessary signals */
+		sig_action.sa_handler = signal_handler;
+		sigemptyset(&sig_action.sa_mask);
+		sig_action.sa_flags = 0;
+
+		sigaction(SIGTERM, &sig_action, NULL);
+		sigaction(SIGHUP, &sig_action, NULL);
+		sigaction(SIGINT, &sig_action, NULL);
+
+		/* create new session and process group */
+		setsid();
+
+		/* persist pid */
+		pidfile_write(pfh);
+
+	}
+
+	/* TODO: Network Logic Here */
+	while (1) {
+
+		sleep(5);
+
+	}
+
+	return (0);
+}
+
+int 
+main(int argc, char *argv[])
+{
+	if (argc > 1) {
+		char *first_arg = argv[1];
+
+		if (!strcmp(first_arg, "start")) {
+			return daemon_start();
+		}
+	}
+	return (EXIT_SUCCESS);
+}