[PATCH v6 1/3] net: Enhancements for dhcp option 209

Sean Edmond
2024-04-29T18:35:21Z

- Enable option 209 by default
- Set pxelinux_configfile to NULL to avoid potential double free
- change hardcoded 209 to a define

Signed-off-by: Sean Edmond <seanedmond@microsoft.com>

---

Changes in v7:
- Reword this commit

Changes in v6:
- Reword this commit

Changes in v4:
- rebase master and resolve conflicts
- default y for BOOTP_PXE_DHCP_OPTION (feedback from review)
- change commit description for this patch (this is now
an enhancement patch)

Changes in v3:
- add define for option 209 and rfc5071 reference

cmd/Kconfig | 1 +
cmd/pxe.c | 2 ++
net/bootp.c | 4 ++--
net/bootp.h | 2 ++
4 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/cmd/Kconfig b/cmd/Kconfig
index c182d73ddbd..54c4ab8570c 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1898,6 +1898,7 @@ 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
diff --git a/cmd/pxe.c b/cmd/pxe.c
index 21134eb7a30..9404f445187 100644
--- a/cmd/pxe.c
+++ b/cmd/pxe.c
@@ -65,6 +65,8 @@ 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;
}
diff --git a/net/bootp.c b/net/bootp.c
index c15472f5d37..b9e3cccb4f9 100644
--- a/net/bootp.c
+++ b/net/bootp.c
@@ -603,7 +603,7 @@ static int dhcp_extended(u8 *e, int message_type, struct in_addr server_ip,
*cnt += 1;
#endif
if (IS_ENABLED(CONFIG_BOOTP_PXE_DHCP_OPTION)) {
- *e++ = 209; /* PXELINUX Config File */
+ *e++ = DHCP_OPTION_PXE_CONFIG_FILE; /* PXELINUX Config File */
*cnt += 1;
}
/* no options, so back up to avoid sending an empty request list */
@@ -922,7 +922,7 @@ static void dhcp_process_options(uchar *popt, uchar *end)
net_boot_file_name[size] = 0;
}
break;
- case 209: /* PXELINUX Config File */
+ case DHCP_OPTION_PXE_CONFIG_FILE: /* PXELINUX Config File */
if (IS_ENABLED(CONFIG_BOOTP_PXE_DHCP_OPTION)) {
/* In case it has already been allocated when get DHCP Offer packet,
* free first to avoid memory leak.
diff --git a/net/bootp.h b/net/bootp.h
index 4e32b19d424..24b32c73f62 100644
--- a/net/bootp.h
+++ b/net/bootp.h
@@ -91,6 +91,8 @@ typedef enum { INIT,
#define DHCP_NAK 6
#define DHCP_RELEASE 7

+#define DHCP_OPTION_PXE_CONFIG_FILE 209 /* "ConfigFile" option according to rfc5071 */
+
/**********************************************************************/

#endif /* __BOOTP_H__ */
--
2.42.0