Merge patch series "BOOTP/DHCPv4 enhancements"

Sean Edmond <[email protected]> says:

In our datacenter application, a single DHCP server is servicing 36000+ clients.
Improvements are required to the DHCPv4 retransmission behavior to align with
RFC and ensure less pressure is exerted on the server:
- retransmission backoff interval maximum is configurable
  (environment variable bootpretransmitperiodmax)
- initial retransmission backoff interval is configurable
  (environment variable bootpretransmitperiodinit)
- transaction ID is kept the same for each BOOTP/DHCPv4 request
  (not recreated on each retry)

For our application we'll use:
- bootpretransmitperiodmax=16000
- bootpretransmitperiodinit=2000

A new configuration BOOTP_RANDOM_XID has been added to enable a randomized
BOOTP/DHCPv4 transaction ID.

Enhance DHCPv4 sending/parsing option 209 (PXE config file).  A previous
patch was accepted.  A new patch fixes a possible double free() and
addresses latest review comments.

Link: https://lore.kernel.org/r/[email protected]

2 files changed, 27 insertions, 0 deletions

diff --git a/cmd/Kconfig b/cmd/Kconfig
index f21d27cb27f..9a70c7a0b83 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1986,6 +1986,7 @@ config BOOTP_PXE_CLIENTARCH
 
 config BOOTP_PXE_DHCP_OPTION
 	bool "Request & store 'pxe_configfile' from BOOTP/DHCP server"
+	default y
 	depends on BOOTP_PXE
 
 config BOOTP_VCI_STRING
@@ -1996,6 +1997,30 @@ 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
+	hex
+	default 0x16 if ARM64
+	default 0x15 if ARM
+	default 0xFF
+
+config DHCP6_PXE_DHCP_OPTION
+	bool "Request & store 'pxe_configfile' from DHCP6 server"
+
+config DHCP6_ENTERPRISE_ID
+	int "Enterprise ID to send in DHCPv6 Vendor Class Option"
+	default 0
+
+endif
+
 config CMD_TFTPPUT
 	bool "tftp put"
 	depends on CMD_TFTPBOOT
diff --git a/cmd/pxe.c b/cmd/pxe.c
index 0f26b3b4219..71d8b542b28 100644
--- a/cmd/pxe.c
+++ b/cmd/pxe.c
@@ -64,6 +64,8 @@ static int pxe_dhcp_option_path(struct pxe_context *ctx, unsigned long pxefile_a
 	int ret = get_pxe_file(ctx, pxelinux_configfile, pxefile_addr_r);
 
 	free(pxelinux_configfile);
+	/* set to NULL to avoid double-free if DHCP is tried again */
+	pxelinux_configfile = NULL;
 
 	return ret;
 }