net: bootp: add config option BOOTP_RANDOM_XID

The new config option BOOTP_RANDOM_XID will randomize the transaction ID
for each new BOOT/DHCPv4 exchange.

Signed-off-by: Sean Edmond <seanedmond@microsoft.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

diff --git a/cmd/Kconfig b/cmd/Kconfig
index 54c4ab8570c4530a44fad1345b86a87016f78981..82f6a089586d2329b4a597803a3d91d610fe3401 100644 (file)
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1909,6 +1909,13 @@ config BOOTP_VCI_STRING
        default "U-Boot.arm" if ARM
        default "U-Boot"
 
+config BOOTP_RANDOM_XID
+       bool "Send random transaction ID to BOOTP/DHCP server"
+       depends on CMD_BOOTP && (LIB_RAND || LIB_HW_RAND)
+       help
+         Selecting this will allow for a random transaction ID to get
+         selected for each BOOTP/DHCPv4 exchange.
+
 if CMD_DHCP6
 
 config DHCP6_PXE_CLIENTARCH

diff --git a/net/bootp.c b/net/bootp.c
index c34ffe27854a95a757534a7576f667d9659adf78..285fcba73484b8900c0da87998027b07a1d7c79e 100644 (file)
--- a/net/bootp.c
+++ b/net/bootp.c
@@ -834,22 +834,25 @@ void bootp_request(void)
 
        /* Only generate a new transaction ID for each new BOOTP request */
        if (bootp_try == 1) {
-               /*
-                *      Bootp ID is the lower 4 bytes of our ethernet address
-                *      plus the current time in ms.
-                */
-               bootp_id = ((u32)net_ethaddr[2] << 24)
-                       | ((u32)net_ethaddr[3] << 16)
-                       | ((u32)net_ethaddr[4] << 8)
-                       | (u32)net_ethaddr[5];
-               bootp_id += get_timer(0);
-               bootp_id = htonl(bootp_id);
-               bootp_add_id(bootp_id);
-               net_copy_u32(&bp->bp_id, &bootp_id);
-       } else {
-               net_copy_u32(&bp->bp_id, &bootp_id);
+               if (IS_ENABLED(CONFIG_BOOTP_RANDOM_XID)) {
+                       srand(get_ticks() + rand());
+                       bootp_id = rand();
+               } else {
+                       /*
+                        *      Bootp ID is the lower 4 bytes of our ethernet address
+                        *      plus the current time in ms.
+                        */
+                       bootp_id = ((u32)net_ethaddr[2] << 24)
+                               | ((u32)net_ethaddr[3] << 16)
+                               | ((u32)net_ethaddr[4] << 8)
+                               | (u32)net_ethaddr[5];
+                       bootp_id += get_timer(0);
+                       bootp_id = htonl(bootp_id);
+               }
        }
 
+       bootp_add_id(bootp_id);
+       net_copy_u32(&bp->bp_id, &bootp_id);
        /*
         * Calculate proper packet lengths taking into account the
         * variable size of the options field