[U-Boot] Fix potential empty DHCP Parameter Request List

[Gray Remlin]

 Signed-off-by: Gray Remlin <g_remlin at rocketmail.com>

---
 net/bootp.c |   16 +++++++++++++++-
 1 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/net/bootp.c b/net/bootp.c
index e679f8b..1289e3b 100644
--- a/net/bootp.c
+++ b/net/bootp.c
@@ -417,8 +417,21 @@ static int DhcpExtended (u8 * e, int message_type,
IPaddr_t ServerID, IPaddr_t R
                return x - start;
 #endif

+/*
+ * RFC2132: An empty Parameter Request List is not legitimate,
+ * it must have at minimum one request.
+ */
+#if defined(CONFIG_BOOTP_SUBNETMASK) || \
+    defined(CONFIG_BOOTP_TIMEOFFSET) || \
+    defined(CONFIG_BOOTP_GATEWAY) || \
+    defined(CONFIG_BOOTP_DNS) || \
+    defined(CONFIG_BOOTP_HOSTNAME) || \
+    defined(CONFIG_BOOTP_BOOTFILESIZE) || \
+    defined(CONFIG_BOOTP_BOOTPATH) || \
+    defined(CONFIG_BOOTP_NISDOMAIN) || \
+    defined(CONFIG_BOOTP_NTPSERVER)
        *e++ = 55;              /* Parameter Request List */
-        cnt = e++;             /* Pointer to count of requested items */
+       cnt = e++;              /* Pointer to count of requested items */
        *cnt = 0;
 #if defined(CONFIG_BOOTP_SUBNETMASK)
        *e++  = 1;              /* Subnet Mask */
@@ -456,6 +469,7 @@ static int DhcpExtended (u8 * e, int message_type,
IPaddr_t ServerID, IPaddr_t R
        *e++  = 42;
        *cnt += 1;
 #endif
+#endif
        *e++  = 255;            /* End of the list */

        /* Pad to minimal length */
--