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/*

 * Copyright (c) 1982, 1986, 1988, 1993

 *      The Regents of the University of California.  All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. All advertising materials mentioning features or use of this software

 *    must display the following acknowledgement:

 *      This product includes software developed by the University of

 *      California, Berkeley and its contributors.

 * 4. Neither the name of the University nor the names of its contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 *

 *      $Id: ip_divert.c,v 1.2 2001-09-27 12:01:55 chris Exp $

 */

#include <sys/param.h>

#include <sys/queue.h>

#include <sys/malloc.h>

#include <sys/mbuf.h>

#include <sys/socket.h>

#include <sys/protosw.h>

#include <sys/socketvar.h>

#include <sys/errno.h>

#include <sys/systm.h>

#include <net/if.h>

#include <net/route.h>

#include <netinet/in.h>

#include <netinet/in_systm.h>

#include <netinet/ip.h>

#include <netinet/in_pcb.h>

#include <netinet/in_var.h>

#include <netinet/ip_var.h>

/*

 * Divert sockets

 */

/*

 * Allocate enough space to hold a full IP packet

 */

#define DIVSNDQ         (65536 + 100)

#define DIVRCVQ         (65536 + 100)

/* Global variables */

/*

 * ip_input() and ip_output() set this secret value before calling us to

 * let us know which divert port to divert a packet to; this is done so

 * we can use the existing prototype for struct protosw's pr_input().

 * This is stored in host order.

 */

u_short ip_divert_port;

/*

 * We set this value to a non-zero port number when we want the call to

 * ip_fw_chk() in ip_input() or ip_output() to ignore ``divert <port>''

 * chain entries. This is stored in host order.

 */

u_short ip_divert_ignore;

/* Internal variables */

static struct inpcbhead divcb;

static struct inpcbinfo divcbinfo;

static u_long   div_sendspace = DIVSNDQ;        /* XXX sysctl ? */

static u_long   div_recvspace = DIVRCVQ;        /* XXX sysctl ? */

/* Optimization: have this preinitialized */

static struct sockaddr_in divsrc = { sizeof(divsrc), AF_INET };

/* Internal functions */

static int div_output(struct socket *so,

                struct mbuf *m, struct mbuf *addr, struct mbuf *control);

/*

 * Initialize divert connection block queue.

 */

void

div_init(void)

{

        LIST_INIT(&divcb);

        divcbinfo.listhead = &divcb;

        /*

         * XXX We don't use the hash list for divert IP, but it's easier

         * to allocate a one entry hash list than it is to check all

         * over the place for hashbase == NULL.

         */

        divcbinfo.hashbase = hashinit(1, M_PCB, &divcbinfo.hashmask);

}

/*

 * Setup generic address and protocol structures

 * for div_input routine, then pass them along with

 * mbuf chain. ip->ip_len is assumed to have had

 * the header length (hlen) subtracted out already.

 * We tell whether the packet was incoming or outgoing

 * by seeing if hlen == 0, which is a hack.

 */

void

div_input(struct mbuf *m, int hlen)

{

        struct ip *ip;

        struct inpcb *inp;

        struct socket *sa;

        /* Sanity check */

        if (ip_divert_port == 0)

                panic("div_input: port is 0");

        /* Assure header */

        if (m->m_len < sizeof(struct ip) &&

            (m = m_pullup(m, sizeof(struct ip))) == 0) {

                return;

        }

        ip = mtod(m, struct ip *);

        /* Record divert port */

        divsrc.sin_port = htons(ip_divert_port);

        /* Restore packet header fields */

        ip->ip_len += hlen;

        HTONS(ip->ip_len);

        HTONS(ip->ip_off);

        /* Record receive interface address, if any */

        divsrc.sin_addr.s_addr = 0;

        if (hlen) {

                struct ifaddr *ifa;

#ifdef DIAGNOSTIC

                /* Sanity check */

                if (!(m->m_flags & M_PKTHDR))

                        panic("div_input: no pkt hdr");

#endif

                /* More fields affected by ip_input() */

                HTONS(ip->ip_id);

                /* Find IP address for recieve interface */

                for (ifa = m->m_pkthdr.rcvif->if_addrlist;

                    ifa != NULL; ifa = ifa->ifa_next) {

                        if (ifa->ifa_addr == NULL)

                                continue;

                        if (ifa->ifa_addr->sa_family != AF_INET)

                                continue;

                        divsrc.sin_addr =

                            ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;

                        break;

                }

        }

        /* Put packet on socket queue, if any */

        sa = NULL;

        for (inp = divcb.lh_first; inp != NULL; inp = inp->inp_list.le_next) {

                if (inp->inp_lport == htons(ip_divert_port))

                        sa = inp->inp_socket;

        }

        if (sa) {

                if (sbappendaddr(&sa->so_rcv, (struct sockaddr *)&divsrc,

                                m, (struct mbuf *)0) == 0)

                        m_freem(m);

                else

                        sorwakeup(sa);

        } else {

                m_freem(m);

                ipstat.ips_noproto++;

                ipstat.ips_delivered--;

        }

}

/*

 * Deliver packet back into the IP processing machinery.

 *

 * If no address specified, or address is 0.0.0.0, send to ip_output();

 * otherwise, send to ip_input() and mark as having been received on

 * the interface with that address.

 *

 * If no address specified, or dest port is 0, allow packet to divert

 * back to this socket; otherwise, don't.

 */

static int

div_output(so, m, addr, control)

        struct socket *so;

        register struct mbuf *m;

        struct mbuf *addr, *control;

{

        register struct inpcb *const inp = sotoinpcb(so);

        register struct ip *const ip = mtod(m, struct ip *);

        struct sockaddr_in *sin = NULL;

        int error = 0;

        if (control)

                m_freem(control);               /* XXX */

        if (addr)

                sin = mtod(addr, struct sockaddr_in *);

        /* Loopback avoidance option */

        ip_divert_ignore = ntohs(inp->inp_lport);

        /* Reinject packet into the system as incoming or outgoing */

        if (!sin || sin->sin_addr.s_addr == 0) {

                /* Don't allow both user specified and setsockopt options,

                   and don't allow packet length sizes that will crash */

                if (((ip->ip_hl != (sizeof (*ip) >> 2)) && inp->inp_options) ||

                     ((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len)) {

                        error = EINVAL;

                        goto cantsend;

                }

                /* Convert fields to host order for ip_output() */

                NTOHS(ip->ip_len);

                NTOHS(ip->ip_off);

                /* Send packet to output processing */

                ipstat.ips_rawout++;                    /* XXX */

                error = ip_output(m, inp->inp_options, &inp->inp_route,

                        (so->so_options & SO_DONTROUTE) |

                        IP_ALLOWBROADCAST | IP_RAWOUTPUT, inp->inp_moptions);

        } else {

                struct ifaddr *ifa;

                /* Find receive interface with the given IP address */

                sin->sin_port = 0;

                if ((ifa = ifa_ifwithaddr((struct sockaddr *) sin)) == 0) {

                        error = EADDRNOTAVAIL;

                        goto cantsend;

                }

                m->m_pkthdr.rcvif = ifa->ifa_ifp;

                /* Send packet to input processing */

                ip_input(m);

        }

        /* Reset for next time (and other packets) */

        ip_divert_ignore = 0;

        return error;

cantsend:

        ip_divert_ignore = 0;

        m_freem(m);

        return error;

}

/*ARGSUSED*/

int

div_usrreq(so, req, m, nam, control)

        register struct socket *so;

        int req;

        struct mbuf *m, *nam, *control;

{

        register int error = 0;

        register struct inpcb *inp = sotoinpcb(so);

        int s;

        if (inp == NULL && req != PRU_ATTACH) {

                error = EINVAL;

                goto release;

        }

        switch (req) {

        case PRU_ATTACH:

                if (inp)

                        panic("div_attach");

                if ((so->so_state & SS_PRIV) == 0) {

                        error = EACCES;

                        break;

                }

                s = splnet();

                error = in_pcballoc(so, &divcbinfo);

                splx(s);

                if (error)

                        break;

                error = soreserve(so, div_sendspace, div_recvspace);

                if (error)

                        break;

                inp = (struct inpcb *)so->so_pcb;

                inp->inp_ip_p = (int)nam;       /* XXX */

                inp->inp_flags |= INP_HDRINCL;

                /* The socket is always "connected" because

                   we always know "where" to send the packet */

                so->so_state |= SS_ISCONNECTED;

                break;

        case PRU_DISCONNECT:

                if ((so->so_state & SS_ISCONNECTED) == 0) {

                        error = ENOTCONN;

                        break;

                }

                /* FALLTHROUGH */

        case PRU_ABORT:

                soisdisconnected(so);

                /* FALLTHROUGH */

        case PRU_DETACH:

                if (inp == 0)

                        panic("div_detach");

                in_pcbdetach(inp);

                break;

        case PRU_BIND:

                s = splnet();

                error = in_pcbbind(inp, nam);

                splx(s);

                break;

        /*

         * Mark the connection as being incapable of further input.

         */

        case PRU_SHUTDOWN:

                socantsendmore(so);

                break;

        case PRU_SEND:

                /* Packet must have a header (but that's about it) */

                if (m->m_len < sizeof (struct ip) ||

                    (m = m_pullup(m, sizeof (struct ip))) == 0) {

                        ipstat.ips_toosmall++;

                        error = EINVAL;

                        break;

                }

                /* Send packet */

                error = div_output(so, m, nam, control);

                m = NULL;

                break;

        case PRU_SOCKADDR:

                in_setsockaddr(inp, nam);

                break;

        case PRU_SENSE:

                /*

                 * stat: don't bother with a blocksize.

                 */

                return (0);

        /*

         * Not supported.

         */

        case PRU_CONNECT:

        case PRU_CONNECT2:

        case PRU_CONTROL:

        case PRU_RCVOOB:

        case PRU_RCVD:

        case PRU_LISTEN:

        case PRU_ACCEPT:

        case PRU_SENDOOB:

        case PRU_PEERADDR:

                error = EOPNOTSUPP;

                break;

        default:

                panic("div_usrreq");

        }

release:

        if (m)

                m_freem(m);

        return (error);

}