/*-
 * alias_skinny.c
 *
 * Copyright (c) 2002, 2003 MarcusCom, Inc.
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 *
 * Author: Joe Marcus Clarke <marcus@FreeBSD.org>
 *
 * $FreeBSD: src/sys/netinet/libalias/alias_skinny.c,v 1.14.8.1 2009/04/15 03:14:26 kensmith Exp $
 */

#ifdef _KERNEL
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/module.h>
#else
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#endif

#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>

#ifdef _KERNEL
#include <netinet/libalias/alias_local.h>
#include <netinet/libalias/alias_mod.h>
#else
#include "alias_local.h"
#include "alias_mod.h"
#endif

static void
AliasHandleSkinny(struct libalias *, struct ip *, struct alias_link *);

static int
fingerprint(struct libalias *la, struct ip *pip, struct alias_data *ah)
{

    if (ah->dport == NULL || ah->sport == NULL || ah->lnk == NULL)
        return (-1);
    if (la->skinnyPort != 0 && (ntohs(*ah->sport) == la->skinnyPort ||
                    ntohs(*ah->dport) == la->skinnyPort))
        return (0);
    return (-1);
}

static int
protohandler(struct libalias *la, struct ip *pip, struct alias_data *ah)
{

        AliasHandleSkinny(la, pip, ah->lnk);
    return (0);
}

struct proto_handler handlers[] = {
    {
      .pri = 110,
      .dir = IN|OUT,
      .proto = TCP,
      .fingerprint = &fingerprint,
      .protohandler = &protohandler
    },
    { EOH }
};

static int
mod_handler(module_t mod, int type, void *data)
{
    int error;

    switch (type) {
    case MOD_LOAD:
        error = 0;
        LibAliasAttachHandlers(handlers);
        break;
    case MOD_UNLOAD:
        error = 0;
        LibAliasDetachHandlers(handlers);
        break;
    default:
        error = EINVAL;
    }
    return (error);
}

#ifdef _KERNEL
static
#endif
moduledata_t alias_mod = {
       "alias_skinny", mod_handler, NULL
};

#ifdef  _KERNEL
DECLARE_MODULE(alias_skinny, alias_mod, SI_SUB_DRIVERS, SI_ORDER_SECOND);
MODULE_VERSION(alias_skinny, 1);
MODULE_DEPEND(alias_skinny, libalias, 1, 1, 1);
#endif

/*
 * alias_skinny.c handles the translation for the Cisco Skinny Station
 * protocol.  Skinny typically uses TCP port 2000 to set up calls between
 * a Cisco Call Manager and a Cisco IP phone.  When a phone comes on line,
 * it first needs to register with the Call Manager.  To do this it sends
 * a registration message.  This message contains the IP address of the
 * IP phone.  This message must then be translated to reflect our global
 * IP address.  Along with the registration message (and usually in the
 * same packet), the phone sends an IP port message.  This message indicates
 * the TCP port over which it will communicate.
 *
 * When a call is placed from the phone, the Call Manager will send an
 * Open Receive Channel message to the phone to let the caller know someone
 * has answered.  The phone then sends back an Open Receive Channel
 * Acknowledgement.  In this packet, the phone sends its IP address again,
 * and the UDP port over which the voice traffic should flow.  These values
 * need translation.  Right after the Open Receive Channel Acknowledgement,
 * the Call Manager sends a Start Media Transmission message indicating the
 * call is connected.  This message contains the IP address and UDP port
 * number of the remote (called) party.  Once this message is translated, the
 * call can commence.  The called part sends the first UDP packet to the
 * calling phone at the pre-arranged UDP port in the Open Receive Channel
 * Acknowledgement.
 *
 * Skinny is a Cisco-proprietary protocol and is a trademark of Cisco Systems,
 * Inc.  All rights reserved.
*/

/* #define LIBALIAS_DEBUG 1 */

/* Message types that need translating */
#define REG_MSG         0x00000001
#define IP_PORT_MSG     0x00000002
#define OPNRCVCH_ACK    0x00000022
#define START_MEDIATX   0x0000008a

struct skinny_header {
    u_int32_t   len;
    u_int32_t   reserved;
    u_int32_t   msgId;
};

struct RegisterMessage {
    u_int32_t   msgId;
    char        devName   [16];
    u_int32_t   uid;
    u_int32_t   instance;
    u_int32_t   ipAddr;
    u_char      devType;
    u_int32_t   maxStreams;
};

struct IpPortMessage {
    u_int32_t   msgId;
    u_int32_t   stationIpPort;  /* Note: Skinny uses 32-bit port
                     * numbers */
};

struct OpenReceiveChannelAck {
    u_int32_t   msgId;
    u_int32_t   status;
    u_int32_t   ipAddr;
    u_int32_t   port;
    u_int32_t   passThruPartyID;
};

struct StartMediaTransmission {
    u_int32_t   msgId;
    u_int32_t   conferenceID;
    u_int32_t   passThruPartyID;
    u_int32_t   remoteIpAddr;
    u_int32_t   remotePort;
    u_int32_t   MSPacket;
    u_int32_t   payloadCap;
    u_int32_t   precedence;
    u_int32_t   silenceSuppression;
    u_short     maxFramesPerPacket;
    u_int32_t   G723BitRate;
};

typedef enum {
    ClientToServer = 0,
    ServerToClient = 1
} ConvDirection;


static int
alias_skinny_reg_msg(struct RegisterMessage *reg_msg, struct ip *pip,
    struct tcphdr *tc, struct alias_link *lnk,
    ConvDirection direction)
{
    (void)direction;

    reg_msg->ipAddr = (u_int32_t) GetAliasAddress(lnk).s_addr;

    tc->th_sum = 0;
#ifdef _KERNEL
    tc->th_x2 = 1;
#else
    tc->th_sum = TcpChecksum(pip);
#endif

    return (0);
}

static int
alias_skinny_startmedia(struct StartMediaTransmission *start_media,
    struct ip *pip, struct tcphdr *tc,
    struct alias_link *lnk, u_int32_t localIpAddr,
    ConvDirection direction)
{
    struct in_addr dst, src;

    (void)pip;
    (void)tc;
    (void)lnk;
    (void)direction;

    dst.s_addr = start_media->remoteIpAddr;
    src.s_addr = localIpAddr;

    /*
     * XXX I should probably handle in bound global translations as
     * well.
     */

    return (0);
}

static int
alias_skinny_port_msg(struct IpPortMessage *port_msg, struct ip *pip,
    struct tcphdr *tc, struct alias_link *lnk,
    ConvDirection direction)
{
    (void)direction;

    port_msg->stationIpPort = (u_int32_t) ntohs(GetAliasPort(lnk));

    tc->th_sum = 0;
#ifdef _KERNEL
    tc->th_x2 = 1;
#else
    tc->th_sum = TcpChecksum(pip);
#endif
    return (0);
}

static int
alias_skinny_opnrcvch_ack(struct libalias *la, struct OpenReceiveChannelAck *opnrcvch_ack,
    struct ip *pip, struct tcphdr *tc,
    struct alias_link *lnk, u_int32_t * localIpAddr,
    ConvDirection direction)
{
    struct in_addr null_addr;
    struct alias_link *opnrcv_lnk;
    u_int32_t localPort;

    (void)lnk;
    (void)direction;

    *localIpAddr = (u_int32_t) opnrcvch_ack->ipAddr;
    localPort = opnrcvch_ack->port;

    null_addr.s_addr = INADDR_ANY;
    opnrcv_lnk = FindUdpTcpOut(la, pip->ip_src, null_addr,
        htons((u_short) opnrcvch_ack->port), 0,
        IPPROTO_UDP, 1);
    opnrcvch_ack->ipAddr = (u_int32_t) GetAliasAddress(opnrcv_lnk).s_addr;
    opnrcvch_ack->port = (u_int32_t) ntohs(GetAliasPort(opnrcv_lnk));

    tc->th_sum = 0;
#ifdef _KERNEL
    tc->th_x2 = 1;
#else
    tc->th_sum = TcpChecksum(pip);
#endif
    return (0);
}

static void
AliasHandleSkinny(struct libalias *la, struct ip *pip, struct alias_link *lnk)
{
    size_t hlen, tlen, dlen;
    struct tcphdr *tc;
    u_int32_t msgId, t, len, lip;
    struct skinny_header *sd;
    size_t orig_len, skinny_hdr_len = sizeof(struct skinny_header);
    ConvDirection direction;

    lip = -1;
    tc = (struct tcphdr *)ip_next(pip);
    hlen = (pip->ip_hl + tc->th_off) << 2;
    tlen = ntohs(pip->ip_len);
    dlen = tlen - hlen;

    sd = (struct skinny_header *)tcp_next(tc);

    /*
     * XXX This direction is reserved for future use.  I still need to
     * handle the scenario where the call manager is on the inside, and
     * the calling phone is on the global outside.
     */
    if (ntohs(tc->th_dport) == la->skinnyPort) {
        direction = ClientToServer;
    } else if (ntohs(tc->th_sport) == la->skinnyPort) {
        direction = ServerToClient;
    } else {
#ifdef LIBALIAS_DEBUG
        fprintf(stderr,
            "PacketAlias/Skinny: Invalid port number, not a Skinny packet\n");
#endif
        return;
    }

    orig_len = dlen;
    /*
     * Skinny packets can contain many messages.  We need to loop
     * through the packet using len to determine message boundaries.
     * This comes into play big time with port messages being in the
     * same packet as register messages.  Also, open receive channel
     * acks are usually buried in a pakcet some 400 bytes long.
     */
    while (dlen >= skinny_hdr_len) {
        len = (sd->len);
        msgId = (sd->msgId);
        t = len;

        if (t > orig_len || t > dlen) {
#ifdef LIBALIAS_DEBUG
            fprintf(stderr,
                "PacketAlias/Skinny: Not a skinny packet, invalid length \n");
#endif
            return;
        }
        switch (msgId) {
        case REG_MSG: {
            struct RegisterMessage *reg_mesg;

            if (len < (int)sizeof(struct RegisterMessage)) {
#ifdef LIBALIAS_DEBUG
                fprintf(stderr,
                    "PacketAlias/Skinny: Not a skinny packet, bad registration message\n");
#endif
                return;
            }
            reg_mesg = (struct RegisterMessage *)&sd->msgId;
#ifdef LIBALIAS_DEBUG
            fprintf(stderr,
                "PacketAlias/Skinny: Received a register message");
#endif
            alias_skinny_reg_msg(reg_mesg, pip, tc, lnk, direction);
            break;
        }
        case IP_PORT_MSG: {
            struct IpPortMessage *port_mesg;

            if (len < (int)sizeof(struct IpPortMessage)) {
#ifdef LIBALIAS_DEBUG
                fprintf(stderr,
                    "PacketAlias/Skinny: Not a skinny packet, port message\n");
#endif
                return;
            }
#ifdef LIBALIAS_DEBUG
            fprintf(stderr,
                "PacketAlias/Skinny: Received ipport message\n");
#endif
            port_mesg = (struct IpPortMessage *)&sd->msgId;
            alias_skinny_port_msg(port_mesg, pip, tc, lnk, direction);
            break;
        }
        case OPNRCVCH_ACK: {
            struct OpenReceiveChannelAck *opnrcvchn_ack;

            if (len < (int)sizeof(struct OpenReceiveChannelAck)) {
#ifdef LIBALIAS_DEBUG
                fprintf(stderr,
                    "PacketAlias/Skinny: Not a skinny packet, packet,OpnRcvChnAckMsg\n");
#endif
                return;
            }
#ifdef LIBALIAS_DEBUG
            fprintf(stderr,
                "PacketAlias/Skinny: Received open rcv channel msg\n");
#endif
            opnrcvchn_ack = (struct OpenReceiveChannelAck *)&sd->msgId;
            alias_skinny_opnrcvch_ack(la, opnrcvchn_ack, pip, tc, lnk, &lip, direction);
            break;
        }
        case START_MEDIATX: {
            struct StartMediaTransmission *startmedia_tx;

            if (len < (int)sizeof(struct StartMediaTransmission)) {
#ifdef LIBALIAS_DEBUG
                fprintf(stderr,
                    "PacketAlias/Skinny: Not a skinny packet,StartMediaTx Message\n");
#endif
                return;
            }
            if (lip == -1) {
#ifdef LIBALIAS_DEBUG
                fprintf(stderr,
                    "PacketAlias/Skinny: received a"
                    " packet,StartMediaTx Message before"
                    " packet,OpnRcvChnAckMsg\n"
#endif
                return;
            }

#ifdef LIBALIAS_DEBUG
            fprintf(stderr,
                "PacketAlias/Skinny: Received start media trans msg\n");
#endif
            startmedia_tx = (struct StartMediaTransmission *)&sd->msgId;
            alias_skinny_startmedia(startmedia_tx, pip, tc, lnk, lip, direction);
            break;
        }
        default:
            break;
        }
        /* Place the pointer at the next message in the packet. */
        dlen -= len + (skinny_hdr_len - sizeof(msgId));
        sd = (struct skinny_header *)(((char *)&sd->msgId) + len);
    }
}
