net: Handle an empty bootp extension section

Avoid generating this section if there is nothing in it.

Signed-off-by: Andre Renaud <andre@designa-electronics.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

diff --git a/net/bootp.c b/net/bootp.c
index aa6cdf0a47a5c17a36a711c62e72043890ce2465..42e14eda417436b0b6ef133055185e2ecb895029 100644 (file)
--- a/net/bootp.c
+++ b/net/bootp.c
@@ -673,6 +673,15 @@ static int bootp_extended(u8 *e)
 
        *e++ = 255;             /* End of the list */
 
+       /*
+        * If nothing in list, remove it altogether. Some DHCP servers get
+        * upset by this minor faux pas and do not respond at all.
+        */
+       if (e == start + 3) {
+               printf("*** Warning: no DHCP options requested\n");
+               e -= 3;
+       }
+
        return e - start;
 }
 #endif