udhcpc: check that 4-byte options are indeed 4-byte, closes 11506

function                                             old     new   delta
udhcp_get_option32                                     -      27     +27
udhcp_get_option                                     231     248     +17
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/0 up/down: 44/0)               Total: 44 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h
index 7ad603d33..9511152ff 100644
--- a/networking/udhcp/common.h
+++ b/networking/udhcp/common.h
@@ -205,6 +205,10 @@ extern const uint8_t dhcp_option_lengths[] ALIGN1;
 unsigned FAST_FUNC udhcp_option_idx(const char *name, const char *option_strings);
 
 uint8_t *udhcp_get_option(struct dhcp_packet *packet, int code) FAST_FUNC;
+/* Same as above + ensures that option length is 4 bytes
+ * (returns NULL if size is different)
+ */
+uint8_t *udhcp_get_option32(struct dhcp_packet *packet, int code) FAST_FUNC;
 int udhcp_end_option(uint8_t *optionptr) FAST_FUNC;
 void udhcp_add_binary_option(struct dhcp_packet *packet, uint8_t *addopt) FAST_FUNC;
 #if ENABLE_UDHCPC || ENABLE_UDHCPD