Implement checking whether LDAP users exist

Makefile.am

@@ -2,7 +2,7 @@ bin_PROGRAMS = nest-sanity
 noinst_PROGRAMS = notify-test
 nest_sanity_CFLAGS = $(LIBCURL_CFLAGS)
 nest_sanity_LDADD = $(LIBCURL_LIBS)
-nest_sanity_SOURCES = sanity.c notify.c runtime-config.c
+nest_sanity_SOURCES = sanity.c notify.c runtime-config.c check-users.c
 notify_test_CFLAGS = $(LIBCURL_CFLAGS)
 notify_test_LDADD = $(LIBCURL_LIBS)
 notify_test_SOURCES = notify.c runtime-config.c notify-test.c

check-users.c

@@ -0,0 +1,51 @@
+#include <sys/types.h>
+#include <pwd.h>
+#include "notify.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include "runtime-config.h"
+/* If samuel truly doesn't exist,
+ * there's probably a bigger issue than just an LDAP failure.
+ */
+#define CHECK_USERS_CANARY_USER "samuel"
+int check_users_state;
+void check_users_init() {
+	check_users_state = 0;
+}
+void check_users() {
+	if(should_enable_debug()) {
+		printf("[D] Starting check_users\n");
+	}
+	struct passwd *res;
+	errno = 0;
+	res = getpwnam(CHECK_USERS_CANARY_USER);
+	if(res == NULL) {
+		/* If we've already reported it, let's not report it again */
+		if(check_users_state == 1) return;
+		int res_errno;
+		res_errno = errno;
+		char *res_err_txt;
+		res_err_txt = strerror(res_errno);
+		char *notification_payload;
+		int notification_payload_len;
+		const char *notification_payload_fmt = "samuel doesn't exist, LDAP is probably broken somehow. (getpwnam returned %s)";
+		/* TODO: set a realistic payload length */
+		notification_payload_len = strlen(notification_payload_fmt) + strlen(res_err_txt) + 1;
+		notification_payload = malloc(notification_payload_len+1);
+		snprintf(notification_payload, notification_payload_len, notification_payload_fmt, res_err_txt);
+		int send_alarm_result;
+		send_alarm_result = send_alarm(notification_payload);
+		/* We only set this to 1 if we successfully reported the issue. */
+		if(send_alarm_result == 0) check_users_state = 1;
+	}
+	else {
+		if(check_users_state > 0) {
+			int send_alarm_result;
+			send_alarm_result = send_alarm("samuel exists again, everything is probably okay now");
+			/* Keep notifying until it sends successfully. */
+			if(send_alarm_result == 0) check_users_state = 0;
+		}
+	}
+}

check-users.h

@@ -0,0 +1,5 @@
+#ifndef CHECK_USERS_H_INCLUDED
+#define CHECK_USERS_H_INCLUDED
+int check_users();
+void check_users_init();
+#endif

runtime-config.c

@@ -5,3 +5,6 @@ char *config_get_url() {
 	/* TODO: find a better way to do this */
 	return getenv("NOTIFY_URL");
 }
+int should_enable_debug() {
+	return getenv("NEST_SANITY_DEBUG")!=NULL?1:0;
+}

runtime-config.h

@@ -1,4 +1,5 @@
 #ifndef RUNTIME_CONFIG_INCLUDED
 #define RUNTIME_CONFIG_INCLUDED
 char *config_get_url();
+int should_enable_debug();
 #endif

sanity.c

@@ -1,7 +1,15 @@
 #include <stdlib.h>
+#include <stdbool.h>
+#include <unistd.h>
 #include "runtime-config.h"
 #include "notify.h"
+#include "check-users.h"
 int main() {
 	notify_init_early();
 	notify_init();
+	check_users_init();
+	while(true) {
+		check_users();
+		sleep(30);
+	}
 }