Fix memory corruption in parse_connection_string

- Fixed 'free(): invalid pointer' error when using service prefix format
- Issue was caused by modifying the original allocated string and then trying to free a pointer to the middle of it
- Added proper pointer tracking to ensure correct memory deallocation

wssshtools/wsssht.c

@@ -70,26 +70,28 @@ int parse_connection_string(const char *conn_str, char **service, char **client_
     char *str = strdup(conn_str);
     if (!str) return 0;
 
+    char *working_str = str; // Keep track of what to free
+
     // Check for service prefix (e.g., "ssh://client@host:port")
     char *service_end = strstr(str, "://");
     if (service_end) {
         *service_end = '\0';
         *service = strdup(str);
-        str = service_end + 3;
+        working_str = service_end + 3; // Point to part after "://"
     }
 
     // Find @ separator for client@host
-    char *at_pos = strchr(str, '@');
+    char *at_pos = strchr(working_str, '@');
     if (!at_pos) {
         // No @ found, treat whole string as client_id
-        *client_id = strdup(str);
+        *client_id = strdup(working_str);
         free(str);
         return 1;
     }
 
     // Split client_id and host part
     *at_pos = '\0';
-    *client_id = strdup(str);
+    *client_id = strdup(working_str);
 
     // Parse host and port
     char *host_part = at_pos + 1;