linux-imx

/* SPDX-License-Identifier: GPL-2.0 */

/*

 *  Definitions for the UDP-Lite (RFC 3828) code.

 */

#ifndef _UDPLITE_H

#define _UDPLITE_H

​

#include <net/ip6_checksum.h>

​

/* UDP-Lite socket options */

#define UDPLITE_SEND_CSCOV   10 /* sender partial coverage (as sent)      */

#define UDPLITE_RECV_CSCOV   11 /* receiver partial coverage (threshold ) */

​

extern struct proto         udplite_prot;

extern struct udp_table     udplite_table;

​

/*

 *  Checksum computation is all in software, hence simpler getfrag.

 */

static __inline__ int udplite_getfrag(void *from, char *to, int  offset,

                      int len, int odd, struct sk_buff *skb)

{

    struct msghdr *msg = from;

    return copy_from_iter_full(to, len, &msg->msg_iter) ? 0 : -EFAULT;

}

​

/* Designate sk as UDP-Lite socket */

static inline int udplite_sk_init(struct sock *sk)

{

    udp_init_sock(sk);

    udp_sk(sk)->pcflag = UDPLITE_BIT;

    return 0;

}

​

/*

 *  Checksumming routines

 */

static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh)

{

    u16 cscov;

​

        /* In UDPv4 a zero checksum means that the transmitter generated no

         * checksum. UDP-Lite (like IPv6) mandates checksums, hence packets

         * with a zero checksum field are illegal.                            */

    if (uh->check == 0) {

        net_dbg_ratelimited("UDPLite: zeroed checksum field\n");

        return 1;

    }

​

    cscov = ntohs(uh->len);

​

    if (cscov == 0)      /* Indicates that full coverage is required. */

        ;

    else if (cscov < 8  || cscov > skb->len) {

        /*

         * Coverage length violates RFC 3828: log and discard silently.

         */

        net_dbg_ratelimited("UDPLite: bad csum coverage %d/%d\n",

                    cscov, skb->len);

        return 1;

​

    } else if (cscov < skb->len) {

            UDP_SKB_CB(skb)->partial_cov = 1;

        UDP_SKB_CB(skb)->cscov = cscov;

        if (skb->ip_summed == CHECKSUM_COMPLETE)

            skb->ip_summed = CHECKSUM_NONE;

        skb->csum_valid = 0;

        }

​

    return 0;

}

​

/* Slow-path computation of checksum. Socket is locked. */

static inline __wsum udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb)

{

    const struct udp_sock *up = udp_sk(skb->sk);

    int cscov = up->len;

    __wsum csum = 0;

​

    if (up->pcflag & UDPLITE_SEND_CC) {

        /*

         * Sender has set `partial coverage' option on UDP-Lite socket.

         * The special case "up->pcslen == 0" signifies full coverage.

         */

        if (up->pcslen < up->len) {

            if (0 < up->pcslen)

                cscov = up->pcslen;

            udp_hdr(skb)->len = htons(up->pcslen);

        }

        /*

         * NOTE: Causes for the error case  `up->pcslen > up->len':

         *        (i)  Application error (will not be penalized).