root/net/ipv4/ipcomp.c

DEFINITIONS

1. ipcomp4_err
2. ipcomp_tunnel_create
3. ipcomp_tunnel_attach
4. ipcomp4_init_state
5. ipcomp4_init
6. ipcomp4_fini

/*
 * IP Payload Compression Protocol (IPComp) - RFC3173.
 *
 * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * Todo:
 *   - Tunable compression parameters.
 *   - Compression stats.
 *   - Adaptive compression.
 */
#include <linux/module.h>
#include <linux/err.h>
#include <linux/rtnetlink.h>
#include <net/ip.h>
#include <net/xfrm.h>
#include <net/icmp.h>
#include <net/ipcomp.h>
#include <net/protocol.h>
#include <net/sock.h>

static void ipcomp4_err(struct sk_buff *skb, u32 info)
{
        __be32 spi;
        struct iphdr *iph = (struct iphdr *)skb->data;
        struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
        struct xfrm_state *x;

        if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
            icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
                return;

        spi = htonl(ntohs(ipch->cpi));
        x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
                              spi, IPPROTO_COMP, AF_INET);
        if (!x)
                return;
        NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIPQUAD_FMT "\n",
                 spi, NIPQUAD(iph->daddr));
        xfrm_state_put(x);
}

/* We always hold one tunnel user reference to indicate a tunnel */
static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
{
        struct xfrm_state *t;

        t = xfrm_state_alloc();
        if (t == NULL)
                goto out;

        t->id.proto = IPPROTO_IPIP;
        t->id.spi = x->props.saddr.a4;
        t->id.daddr.a4 = x->id.daddr.a4;
        memcpy(&t->sel, &x->sel, sizeof(t->sel));
        t->props.family = AF_INET;
        t->props.mode = x->props.mode;
        t->props.saddr.a4 = x->props.saddr.a4;
        t->props.flags = x->props.flags;

        if (xfrm_init_state(t))
                goto error;

        atomic_set(&t->tunnel_users, 1);
out:
        return t;

error:
        t->km.state = XFRM_STATE_DEAD;
        xfrm_state_put(t);
        t = NULL;
        goto out;
}

/*
 * Must be protected by xfrm_cfg_mutex.  State and tunnel user references are
 * always incremented on success.
 */
static int ipcomp_tunnel_attach(struct xfrm_state *x)
{
        int err = 0;
        struct xfrm_state *t;

        t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
                              x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
        if (!t) {
                t = ipcomp_tunnel_create(x);
                if (!t) {
                        err = -EINVAL;
                        goto out;
                }
                xfrm_state_insert(t);
                xfrm_state_hold(t);
        }
        x->tunnel = t;
        atomic_inc(&t->tunnel_users);
out:
        return err;
}

static int ipcomp4_init_state(struct xfrm_state *x)
{
        int err = -EINVAL;

        x->props.header_len = 0;
        switch (x->props.mode) {
        case XFRM_MODE_TRANSPORT:
                break;
        case XFRM_MODE_TUNNEL:
                x->props.header_len += sizeof(struct iphdr);
                break;
        default:
                goto out;
        }

        err = ipcomp_init_state(x);
        if (err)
                goto out;

        if (x->props.mode == XFRM_MODE_TUNNEL) {
                err = ipcomp_tunnel_attach(x);
                if (err)
                        goto error_tunnel;
        }

        err = 0;
out:
        return err;

error_tunnel:
        ipcomp_destroy(x);
        goto out;
}

static const struct xfrm_type ipcomp_type = {
        .description    = "IPCOMP4",
        .owner          = THIS_MODULE,
        .proto          = IPPROTO_COMP,
        .init_state     = ipcomp4_init_state,
        .destructor     = ipcomp_destroy,
        .input          = ipcomp_input,
        .output         = ipcomp_output
};

static struct net_protocol ipcomp4_protocol = {
        .handler        =       xfrm4_rcv,
        .err_handler    =       ipcomp4_err,
        .no_policy      =       1,
};

static int __init ipcomp4_init(void)
{
        if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
                printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
                return -EAGAIN;
        }
        if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
                printk(KERN_INFO "ipcomp init: can't add protocol\n");
                xfrm_unregister_type(&ipcomp_type, AF_INET);
                return -EAGAIN;
        }
        return 0;
}

static void __exit ipcomp4_fini(void)
{
        if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
                printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
        if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
                printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
}

module_init(ipcomp4_init);
module_exit(ipcomp4_fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173");
MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");

MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP);