initial work on daemon

configure.ac

@@ -6,13 +6,13 @@ AC_LANG([C])
 AM_INIT_AUTOMAKE
 
 # Checks for programs.
-AC_PROG_CC
+AC_PROG_CC_C99
 
 # Checks for libraries.
 PKG_CHECK_MODULES([gammu], [gammu >= 1.0])
 
 # Checks for header files.
-AC_CHECK_HEADERS([fcntl.h stdlib.h string.h syslog.h unistd.h])
+AC_CHECK_HEADERS([fcntl.h signal.h stdlib.h string.h syslog.h unistd.h])
 
 # Checks for typedefs, structures, and compiler characteristics.
 

yasnd.c

@@ -1,17 +1,101 @@
-// #include <gammu/gammu.h>
-
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/wait.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <fcntl.h>
 #include <errno.h>
 #include <unistd.h>
 #include <syslog.h>
+#include <signal.h>
 #include <string.h>
+// #include <gammu/gammu.h>
+
+// Target hosts count
+#define NUM_HOSTS 3
+
+// Should we do excessive debug logging or not
+#define DEBUG
+
+typedef struct {
+	char* hostname; // address of host
+	pid_t helper_pid; // pid of helper('pinger') child process
+	int fail_count; // how many times in a row host was unreachable
+} host_decl;
+
+host_decl hosts[NUM_HOSTS];
+
+void init()
+{
+	hosts[0].hostname="10.0.0.1";
+	hosts[0].fail_count=0;
+	hosts[1].hostname="10.0.0.2";
+	hosts[1].fail_count=0;
+	hosts[2].hostname="10.0.0.254";
+	hosts[2].fail_count=0;
+}
+
+void log_event(const char *message)
+{
+	#ifdef DEBUG
+		syslog(LOG_INFO,"%s",message);
+	#endif
+}
+
+void check_host(int num,host_decl host)
+{
+	pid_t pid = fork();
+	if (pid < 0) {
+                exit(EXIT_FAILURE);
+        }
+        // If pid == 0, then we are in the child
+        if (pid == 0) {
+		char tmp[50];
+		sprintf(tmp, "Pinging host %s", host.hostname);
+		log_event(tmp);
+		execl("/bin/ping","/bin/ping","-c 4","-n",host.hostname,(char*) 0);
+		// STUB: check result of exec call
+		exit(EXIT_SUCCESS);
+        }
+	// Save child's pid
+	host.helper_pid=pid;
+}
+
+void loop_function()
+{
+	for (int i=0;i<NUM_HOSTS;i++)
+	{
+		check_host(i,hosts[i]);
+	}
+	for (int i=0;i<NUM_HOSTS;i++)
+	{
+		int pid_status;
+		int result = waitpid(hosts[i].helper_pid, &pid_status, NULL);
+		if (result > 0)
+		{
+			if (WIFEXITED(pid_status))
+			{
+				char tmp[50];
+				sprintf(tmp, "Finished child %d with result %d", result, WEXITSTATUS(pid_status));
+				log_event(tmp);
+				// if host is alive - reset failure counter
+				// otherwise - increment it
+				if (WEXITSTATUS(pid_status) == 0)
+					hosts[i].fail_count=0;
+				else
+					hosts[i].fail_count++;
+			}
+		}
+	}
+}
+
+void termination_handler(int signum)
+{
+	closelog();
+	exit(EXIT_SUCCESS);
+}
 
 int main(void) {
-        
 	/* Our process ID and Session ID */
 	pid_t pid, sid;
 
@@ -20,8 +104,7 @@ int main(void) {
 	if (pid < 0) {
 		exit(EXIT_FAILURE);
 	}
-        /* If we got a good PID, then
-           we can exit the parent process. */
+	/* If we got a good PID, then we can exit the parent process. */
 	if (pid > 0) {
 		exit(EXIT_SUCCESS);
 	}
@@ -30,6 +113,7 @@ int main(void) {
 	umask(0);
 
 	/* Open any logs here */
+	openlog("yasnd", LOG_PID|LOG_CONS, LOG_USER);
 
 	/* Create a new SID for the child process */
 	sid = setsid();
@@ -38,8 +122,6 @@ int main(void) {
 		exit(EXIT_FAILURE);
 	}
 
-
-        
 	/* Change the current working directory */
 	if ((chdir("/")) < 0) {
 		/* Log the failure */
@@ -51,13 +133,17 @@ int main(void) {
 	close(STDOUT_FILENO);
 	close(STDERR_FILENO);
 
-        /* Daemon-specific initialization goes here */
+	// Set signal handler for SIGTERM
+	signal(SIGTERM, termination_handler);
+
+	// Init apropriate structures
+	init();
 
 	/* The Big Loop */
 	while (1) {
-           /* Do some task here ... */
-           
-           sleep(30); /* wait 30 seconds */
+		loop_function();
+//		sleep(60); /* wait 60 seconds */
+		exit(EXIT_SUCCESS);
 	}
 	exit(EXIT_SUCCESS);
 }