[PATCH 03/10] net: dhcp: use net_eth_to_udp() for packet parsing

[Ahmad Fatoum]

On 4/2/26 8:36 AM, Sascha Hauer wrote:
> Replace the separate net_eth_to_udp_payload(), net_eth_to_udphdr() and
> net_eth_to_udplen() calls with the new consolidated net_eth_to_udp()
> helper.  This validates the packet length before accessing any headers.
> 
> Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
> Co-Authored-By: Claude Opus 4.6 <noreply at anthropic.com>

Reviewed-by: Ahmad Fatoum <a.fatoum at pengutronix.de>

> ---
>  net/dhcp.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/net/dhcp.c b/net/dhcp.c
> index e25b64842d..39168a2d53 100644
> --- a/net/dhcp.c
> +++ b/net/dhcp.c
> @@ -391,16 +391,18 @@ static void dhcp_send_request_packet(struct bootp *bp_offer)
>   */
>  static void dhcp_handler(void *ctx, char *packet, unsigned int len)
>  {
> -	char *pkt = net_eth_to_udp_payload(packet);
> -	struct udphdr *udp = net_eth_to_udphdr(packet);
> -	struct bootp *bp = (struct bootp *)pkt;
> +	struct net_udp_pkt udp;
> +	struct bootp *bp;
> +
> +	if (net_eth_to_udp(packet, len, &udp))
> +		return;
>  
> -	len = net_eth_to_udplen(packet);
> +	bp = udp.payload;
>  
> -	debug("DHCPHandler: got packet: (len=%d) state: %d\n",
> -		len, dhcp_state);
> +	debug("DHCPHandler: got packet: (len=%u) state: %d\n",
> +		udp.len, dhcp_state);
>  
> -	if (bootp_check_packet(pkt, ntohs(udp->uh_sport), len)) /* Filter out pkts we don't want */
> +	if (bootp_check_packet(udp.payload, ntohs(udp.udp->uh_sport), udp.len))
>  		return;
>  
>  	switch (dhcp_state) {
> 

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