// SPDX-License-Identifier: GPL-2.0-only
/*
 * File: datagram.c
 *
 * Datagram (ISI) Phonet sockets
 *
 * Copyright (C) 2008 Nokia Corporation.
 *
 * Authors: Sakari Ailus <sakari.ailus@nokia.com>
 *          Rémi Denis-Courmont
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/socket.h>
#include <asm/ioctls.h>
#include <net/sock.h>

#include <linux/phonet.h>
#include <linux/export.h>
#include <net/phonet/phonet.h>

static int pn_backlog_rcv(struct sock *sk, struct sk_buff *skb);

/* associated socket ceases to exist */
static void pn_sock_close(struct sock *sk, long timeout)
{
        sk_common_release(sk);
}

static int pn_ioctl(struct sock *sk, int cmd, int *karg)
{
        struct sk_buff *skb;

        switch (cmd) {
        case SIOCINQ:
                spin_lock_bh(&sk->sk_receive_queue.lock);
                skb = skb_peek(&sk->sk_receive_queue);
                *karg = skb ? skb->len : 0;
                spin_unlock_bh(&sk->sk_receive_queue.lock);
                return 0;

        case SIOCPNADDRESOURCE:
        case SIOCPNDELRESOURCE: {
                        u32 res = *karg;
                        if (res >= 256)
                                return -EINVAL;
                        if (cmd == SIOCPNADDRESOURCE)
                                return pn_sock_bind_res(sk, res);
                        else
                                return pn_sock_unbind_res(sk, res);
                }
        }

        return -ENOIOCTLCMD;
}

/* Destroy socket. All references are gone. */
static void pn_destruct(struct sock *sk)
{
        skb_queue_purge(&sk->sk_receive_queue);
}

static int pn_init(struct sock *sk)
{
        sk->sk_destruct = pn_destruct;
        return 0;
}

static int pn_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
{
        DECLARE_SOCKADDR(struct sockaddr_pn *, target, msg->msg_name);
        struct sk_buff *skb;
        int err;

        if (msg->msg_flags & ~(MSG_DONTWAIT|MSG_EOR|MSG_NOSIGNAL|
                                MSG_CMSG_COMPAT))
                return -EOPNOTSUPP;

        if (target == NULL)
                return -EDESTADDRREQ;

        if (msg->msg_namelen < sizeof(struct sockaddr_pn))
                return -EINVAL;

        if (target->spn_family != AF_PHONET)
                return -EAFNOSUPPORT;

        skb = sock_alloc_send_skb(sk, MAX_PHONET_HEADER + len,
                                        msg->msg_flags & MSG_DONTWAIT, &err);
        if (skb == NULL)
                return err;
        skb_reserve(skb, MAX_PHONET_HEADER);

        err = memcpy_from_msg((void *)skb_put(skb, len), msg, len);
        if (err < 0) {
                kfree_skb(skb);
                return err;
        }

        /*
         * Fill in the Phonet header and
         * finally pass the packet forwards.
         */
        err = pn_skb_send(sk, skb, target);

        /* If ok, return len. */
        return (err >= 0) ? len : err;
}

static int pn_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
                      int flags, int *addr_len)
{
        struct sk_buff *skb = NULL;
        struct sockaddr_pn sa;
        int rval = -EOPNOTSUPP;
        int copylen;

        if (flags & ~(MSG_PEEK|MSG_TRUNC|MSG_DONTWAIT|MSG_NOSIGNAL|
                        MSG_CMSG_COMPAT))
                goto out_nofree;

        skb = skb_recv_datagram(sk, flags, &rval);
        if (skb == NULL)
                goto out_nofree;

        pn_skb_get_src_sockaddr(skb, &sa);

        copylen = skb->len;
        if (len < copylen) {
                msg->msg_flags |= MSG_TRUNC;
                copylen = len;
        }

        rval = skb_copy_datagram_msg(skb, 0, msg, copylen);
        if (rval) {
                rval = -EFAULT;
                goto out;
        }

        rval = (flags & MSG_TRUNC) ? skb->len : copylen;

        if (msg->msg_name != NULL) {
                __sockaddr_check_size(sizeof(sa));
                memcpy(msg->msg_name, &sa, sizeof(sa));
                *addr_len = sizeof(sa);
        }

out:
        skb_free_datagram(sk, skb);

out_nofree:
        return rval;
}

/* Queue an skb for a sock. */
static int pn_backlog_rcv(struct sock *sk, struct sk_buff *skb)
{
        int err = sock_queue_rcv_skb(sk, skb);

        if (err < 0)
                kfree_skb(skb);
        return err ? NET_RX_DROP : NET_RX_SUCCESS;
}

/* Module registration */
static struct proto pn_proto = {
        .close          = pn_sock_close,
        .ioctl          = pn_ioctl,
        .init           = pn_init,
        .sendmsg        = pn_sendmsg,
        .recvmsg        = pn_recvmsg,
        .backlog_rcv    = pn_backlog_rcv,
        .hash           = pn_sock_hash,
        .unhash         = pn_sock_unhash,
        .get_port       = pn_sock_get_port,
        .obj_size       = sizeof(struct pn_sock),
        .owner          = THIS_MODULE,
        .name           = "PHONET",
};

static const struct phonet_protocol pn_dgram_proto = {
        .ops            = &phonet_dgram_ops,
        .prot           = &pn_proto,
        .sock_type      = SOCK_DGRAM,
};

int __init isi_register(void)
{
        return phonet_proto_register(PN_PROTO_PHONET, &pn_dgram_proto);
}

void __exit isi_unregister(void)
{
        phonet_proto_unregister(PN_PROTO_PHONET, &pn_dgram_proto);
}