Prevent NULL pointer crash

It used to be assumed that the user sets the LIMOX_USER and LIMOX_PWD
shell variables but there was no error checking if this was not the
case.

This commit adds the check preventing a crash of the whole program.
Furthermore an error message is printed to the terminal.

1 files changed, 23 insertions, 2 deletions

diff --git a/xmpp.c b/xmpp.c
index 77567e8..c718df4 100644
--- a/xmpp.c
+++ b/xmpp.c
@@ -27,6 +27,7 @@
 #include <sys/socket.h>
 #include <arpa/inet.h>
 #include <netdb.h>
+#include <stdbool.h>
 
 
 /*
@@ -135,6 +136,23 @@ int start_stream(int sock_fd, char *jid, char *domainpart)
 }
 
 /*
+ * Get JID and password and return true on success
+ */
+bool get_credentials(char **jid, char **pwd)
+{
+	if (getenv("LIMOX_USER") == NULL || getenv("LIMOX_PWD") == NULL) {
+		printf("Failed to connect.\n");
+		printf("Please set the LIMOX_USER and LIMOX_PWD shell variables.\n");
+		return false;
+	}
+
+	*jid = getenv("LIMOX_USER");
+	*pwd = getenv("LIMOX_PWD");
+
+	return true;
+}
+
+/*
  * Initialize the network connection to the XMPP server and return socket fd
  *
  * TODO: Error handling is missing.
@@ -143,8 +161,11 @@ int xmpp_connect(void)
 {
 	printf("net_init()\n");
 
-	char *jid = getenv("LIMOX_USER");
-	char *pwd = getenv("LIMOX_PWD");
+	char *jid;
+	char *pwd;
+	if (!get_credentials(&jid, &pwd)) {
+		return -1;
+	}
 	printf("Trying to connect as '%s' with '%s'.\n", jid, pwd);
 
 	char *domain = get_domainpart(jid);