Extract domain from JID with parser function

It is mandatory to have an IP address to dial a TCP connection. FOr this
purpose the JID which is given by the user has to be converted into a
FQDN and then translated to an IP via DNS.

The function added with this commit implements this first part. The
extraction of the domain (more precisely the FQDN) from the JID.

1 files changed, 35 insertions, 1 deletions

diff --git a/xmpp.c b/xmpp.c
index be677fc..865b235 100644
--- a/xmpp.c
+++ b/xmpp.c
@@ -2,16 +2,50 @@
 
 #include <stdlib.h>
 #include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
 
 
+/*
+ * Get the domainpart of the Jabber ID (JID).
+ * See https://datatracker.ietf.org/doc/html/rfc7622#section-3.2 for details.
+ */
+char *domainpart(char *jid)
+{
+	int start = 0;           // inclusive
+	int stop = strlen(jid);  // exclusive
+
+	for(int i=0; i<strlen(jid); i++) {
+		if (jid[i] == '/') {
+			stop = i;
+			break;
+		}
+	}
+
+	for(int i=0; i<strlen(jid); i++) {
+		if (jid[i] == '@') {
+			start = i + 1;
+			break;
+		}
+	}
+
+	char* retval = (char *)malloc((stop-start+1) * sizeof(char));
+	memcpy(retval, jid+start, (stop-start)*sizeof(char));
+	retval[stop] = '\0';
+
+	return retval;
+}
+
 void net_init(void)
 {
 	printf("net_init()\n");
 
 	char* user_str = getenv("LIMOX_USER");
 	char* pwd_str = getenv("LIMOX_PWD");
-
+	char *domain = domainpart(user_str);
 	printf("Trying to connect as '%s' with '%s'.\n", user_str, pwd_str);
+	printf("Domainpart is '%s'.\n", domain);
 }
 
 void net_quit(void)