alias_skinny.c

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    1 /*-
    2  * alias_skinny.c
    3  *
    4  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    5  *
    6  * Copyright (c) 2002, 2003 MarcusCom, Inc.
    7  * All rights reserved.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  *
   18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   28  * SUCH DAMAGE.
   29  *
   30  * Author: Joe Marcus Clarke <marcus@FreeBSD.org>
   31  *
   32  * $FreeBSD$
   33  */
   34 
   35 #ifdef _KERNEL
   36 #include <sys/param.h>
   37 #include <sys/kernel.h>
   38 #include <sys/module.h>
   39 #else
   40 #include <errno.h>
   41 #include <stdio.h>
   42 #include <unistd.h>
   43 #endif
   44 
   45 #include <netinet/in_systm.h>
   46 #include <netinet/in.h>
   47 #include <netinet/ip.h>
   48 #include <netinet/tcp.h>
   49 
   50 #ifdef _KERNEL
   51 #include <netinet/libalias/alias_local.h>
   52 #include <netinet/libalias/alias_mod.h>
   53 #else
   54 #include "alias_local.h"
   55 #include "alias_mod.h"
   56 #endif
   57 
   58 static void
   59 AliasHandleSkinny(struct libalias *, struct ip *, struct alias_link *);
   60 
   61 static int
   62 fingerprint(struct libalias *la, struct alias_data *ah)
   63 {
   64         if (ah->dport == NULL || ah->sport == NULL || ah->lnk == NULL)
   65                 return (-1);
   66         if (la->skinnyPort != 0 && (ntohs(*ah->sport) == la->skinnyPort ||
   67                                     ntohs(*ah->dport) == la->skinnyPort))
   68                 return (0);
   69         return (-1);
   70 }
   71 
   72 static int
   73 protohandler(struct libalias *la, struct ip *pip, struct alias_data *ah)
   74 {
   75         AliasHandleSkinny(la, pip, ah->lnk);
   76         return (0);
   77 }
   78 
   79 struct proto_handler handlers[] = {
   80         {
   81           .pri = 110,
   82           .dir = IN|OUT,
   83           .proto = TCP,
   84           .fingerprint = &fingerprint,
   85           .protohandler = &protohandler
   86         },
   87         { EOH }
   88 };
   89 
   90 static int
   91 mod_handler(module_t mod, int type, void *data)
   92 {
   93         int error;
   94 
   95         switch (type) {
   96         case MOD_LOAD:
   97                 error = 0;
   98                 LibAliasAttachHandlers(handlers);
   99                 break;
  100         case MOD_UNLOAD:
  101                 error = 0;
  102                 LibAliasDetachHandlers(handlers);
  103                 break;
  104         default:
  105                 error = EINVAL;
  106         }
  107         return (error);
  108 }
  109 
  110 #ifdef _KERNEL
  111 static
  112 #endif
  113 moduledata_t alias_mod = {
  114        "alias_skinny", mod_handler, NULL
  115 };
  116 
  117 #ifdef _KERNEL
  118 DECLARE_MODULE(alias_skinny, alias_mod, SI_SUB_DRIVERS, SI_ORDER_SECOND);
  119 MODULE_VERSION(alias_skinny, 1);
  120 MODULE_DEPEND(alias_skinny, libalias, 1, 1, 1);
  121 #endif
  122 
  123 /*
  124  * alias_skinny.c handles the translation for the Cisco Skinny Station
  125  * protocol.  Skinny typically uses TCP port 2000 to set up calls between
  126  * a Cisco Call Manager and a Cisco IP phone.  When a phone comes on line,
  127  * it first needs to register with the Call Manager.  To do this it sends
  128  * a registration message.  This message contains the IP address of the
  129  * IP phone.  This message must then be translated to reflect our global
  130  * IP address.  Along with the registration message (and usually in the
  131  * same packet), the phone sends an IP port message.  This message indicates
  132  * the TCP port over which it will communicate.
  133  *
  134  * When a call is placed from the phone, the Call Manager will send an
  135  * Open Receive Channel message to the phone to let the caller know someone
  136  * has answered.  The phone then sends back an Open Receive Channel
  137  * Acknowledgement.  In this packet, the phone sends its IP address again,
  138  * and the UDP port over which the voice traffic should flow.  These values
  139  * need translation.  Right after the Open Receive Channel Acknowledgement,
  140  * the Call Manager sends a Start Media Transmission message indicating the
  141  * call is connected.  This message contains the IP address and UDP port
  142  * number of the remote (called) party.  Once this message is translated, the
  143  * call can commence.  The called part sends the first UDP packet to the
  144  * calling phone at the pre-arranged UDP port in the Open Receive Channel
  145  * Acknowledgement.
  146  *
  147  * Skinny is a Cisco-proprietary protocol and is a trademark of Cisco Systems,
  148  * Inc.  All rights reserved.
  149 */
  150 
  151 /* #define LIBALIAS_DEBUG 1 */
  152 
  153 /* Message types that need translating */
  154 #define REG_MSG         0x00000001
  155 #define IP_PORT_MSG     0x00000002
  156 #define OPNRCVCH_ACK    0x00000022
  157 #define START_MEDIATX   0x0000008a
  158 
  159 struct skinny_header {
  160         u_int32_t       len;
  161         u_int32_t       reserved;
  162         u_int32_t       msgId;
  163 };
  164 
  165 struct RegisterMessage {
  166         u_int32_t       msgId;
  167         char            devName   [16];
  168         u_int32_t       uid;
  169         u_int32_t       instance;
  170         u_int32_t       ipAddr;
  171         u_char          devType;
  172         u_int32_t       maxStreams;
  173 };
  174 
  175 struct IpPortMessage {
  176         u_int32_t       msgId;
  177         u_int32_t       stationIpPort;  /* Note: Skinny uses 32-bit port
  178                                          * numbers */
  179 };
  180 
  181 struct OpenReceiveChannelAck {
  182         u_int32_t       msgId;
  183         u_int32_t       status;
  184         u_int32_t       ipAddr;
  185         u_int32_t       port;
  186         u_int32_t       passThruPartyID;
  187 };
  188 
  189 struct StartMediaTransmission {
  190         u_int32_t       msgId;
  191         u_int32_t       conferenceID;
  192         u_int32_t       passThruPartyID;
  193         u_int32_t       remoteIpAddr;
  194         u_int32_t       remotePort;
  195         u_int32_t       MSPacket;
  196         u_int32_t       payloadCap;
  197         u_int32_t       precedence;
  198         u_int32_t       silenceSuppression;
  199         u_short         maxFramesPerPacket;
  200         u_int32_t       G723BitRate;
  201 };
  202 
  203 typedef enum {
  204         ClientToServer = 0,
  205         ServerToClient = 1
  206 } ConvDirection;
  207 
  208 static int
  209 alias_skinny_reg_msg(struct RegisterMessage *reg_msg, struct ip *pip,
  210     struct tcphdr *tc, struct alias_link *lnk,
  211     ConvDirection direction)
  212 {
  213         (void)direction;
  214 
  215         reg_msg->ipAddr = (u_int32_t)GetAliasAddress(lnk).s_addr;
  216 
  217         tc->th_sum = 0;
  218 #ifdef _KERNEL
  219         tc->th_x2 = (TH_RES1 >> 8);
  220 #else
  221         tc->th_sum = TcpChecksum(pip);
  222 #endif
  223 
  224         return (0);
  225 }
  226 
  227 static int
  228 alias_skinny_startmedia(struct StartMediaTransmission *start_media,
  229     struct ip *pip, struct tcphdr *tc,
  230     struct alias_link *lnk, u_int32_t localIpAddr,
  231     ConvDirection direction)
  232 {
  233         struct in_addr dst, src;
  234 
  235         (void)pip;
  236         (void)tc;
  237         (void)lnk;
  238         (void)direction;
  239 
  240         dst.s_addr = start_media->remoteIpAddr;
  241         src.s_addr = localIpAddr;
  242 
  243         /*
  244          * XXX I should probably handle in bound global translations as
  245          * well.
  246          */
  247 
  248         return (0);
  249 }
  250 
  251 static int
  252 alias_skinny_port_msg(struct IpPortMessage *port_msg, struct ip *pip,
  253     struct tcphdr *tc, struct alias_link *lnk,
  254     ConvDirection direction)
  255 {
  256         (void)direction;
  257 
  258         port_msg->stationIpPort = (u_int32_t)ntohs(GetAliasPort(lnk));
  259 
  260         tc->th_sum = 0;
  261 #ifdef _KERNEL
  262         tc->th_x2 = (TH_RES1 >> 8);
  263 #else
  264         tc->th_sum = TcpChecksum(pip);
  265 #endif
  266         return (0);
  267 }
  268 
  269 static int
  270 alias_skinny_opnrcvch_ack(struct libalias *la, struct OpenReceiveChannelAck *opnrcvch_ack,
  271     struct ip *pip, struct tcphdr *tc,
  272     struct alias_link *lnk, u_int32_t * localIpAddr,
  273     ConvDirection direction)
  274 {
  275         struct in_addr null_addr;
  276         struct alias_link *opnrcv_lnk;
  277 
  278         (void)lnk;
  279         (void)direction;
  280 
  281         *localIpAddr = (u_int32_t)opnrcvch_ack->ipAddr;
  282 
  283         null_addr.s_addr = INADDR_ANY;
  284         opnrcv_lnk = FindUdpTcpOut(la, pip->ip_src, null_addr,
  285             htons((u_short) opnrcvch_ack->port), 0,
  286             IPPROTO_UDP, 1);
  287         opnrcvch_ack->ipAddr = (u_int32_t)GetAliasAddress(opnrcv_lnk).s_addr;
  288         opnrcvch_ack->port = (u_int32_t)ntohs(GetAliasPort(opnrcv_lnk));
  289 
  290         tc->th_sum = 0;
  291 #ifdef _KERNEL
  292         tc->th_x2 = (TH_RES1 >> 8);
  293 #else
  294         tc->th_sum = TcpChecksum(pip);
  295 #endif
  296         return (0);
  297 }
  298 
  299 static void
  300 AliasHandleSkinny(struct libalias *la, struct ip *pip, struct alias_link *lnk)
  301 {
  302         size_t hlen, tlen, dlen;
  303         struct tcphdr *tc;
  304         u_int32_t msgId, t, len, lip;
  305         struct skinny_header *sd;
  306         size_t orig_len, skinny_hdr_len = sizeof(struct skinny_header);
  307         ConvDirection direction;
  308 
  309         lip = -1;
  310         tc = (struct tcphdr *)ip_next(pip);
  311         hlen = (pip->ip_hl + tc->th_off) << 2;
  312         tlen = ntohs(pip->ip_len);
  313         dlen = tlen - hlen;
  314 
  315         sd = (struct skinny_header *)tcp_next(tc);
  316 
  317         /*
  318          * XXX This direction is reserved for future use.  I still need to
  319          * handle the scenario where the call manager is on the inside, and
  320          * the calling phone is on the global outside.
  321          */
  322         if (ntohs(tc->th_dport) == la->skinnyPort)
  323                 direction = ClientToServer;
  324         else if (ntohs(tc->th_sport) == la->skinnyPort)
  325                 direction = ServerToClient;
  326         else {
  327 #ifdef LIBALIAS_DEBUG
  328                 fprintf(stderr,
  329                     "PacketAlias/Skinny: Invalid port number, not a Skinny packet\n");
  330 #endif
  331                 return;
  332         }
  333 
  334         orig_len = dlen;
  335         /*
  336          * Skinny packets can contain many messages.  We need to loop
  337          * through the packet using len to determine message boundaries.
  338          * This comes into play big time with port messages being in the
  339          * same packet as register messages.  Also, open receive channel
  340          * acks are usually buried in a packet some 400 bytes long.
  341          */
  342         while (dlen >= skinny_hdr_len) {
  343                 len = (sd->len);
  344                 msgId = (sd->msgId);
  345                 t = len;
  346 
  347                 if (t > orig_len || t > dlen) {
  348 #ifdef LIBALIAS_DEBUG
  349                         fprintf(stderr,
  350                             "PacketAlias/Skinny: Not a skinny packet, invalid length \n");
  351 #endif
  352                         return;
  353                 }
  354                 switch (msgId) {
  355                 case REG_MSG: {
  356                         struct RegisterMessage *reg_mesg;
  357 
  358                         if (len < (int)sizeof(struct RegisterMessage)) {
  359 #ifdef LIBALIAS_DEBUG
  360                                 fprintf(stderr,
  361                                     "PacketAlias/Skinny: Not a skinny packet, bad registration message\n");
  362 #endif
  363                                 return;
  364                         }
  365                         reg_mesg = (struct RegisterMessage *)&sd->msgId;
  366 #ifdef LIBALIAS_DEBUG
  367                         fprintf(stderr,
  368                             "PacketAlias/Skinny: Received a register message");
  369 #endif
  370                         alias_skinny_reg_msg(reg_mesg, pip, tc, lnk, direction);
  371                         break;
  372                 }
  373                 case IP_PORT_MSG: {
  374                         struct IpPortMessage *port_mesg;
  375 
  376                         if (len < (int)sizeof(struct IpPortMessage)) {
  377 #ifdef LIBALIAS_DEBUG
  378                                 fprintf(stderr,
  379                                     "PacketAlias/Skinny: Not a skinny packet, port message\n");
  380 #endif
  381                                 return;
  382                         }
  383 #ifdef LIBALIAS_DEBUG
  384                         fprintf(stderr,
  385                             "PacketAlias/Skinny: Received ipport message\n");
  386 #endif
  387                         port_mesg = (struct IpPortMessage *)&sd->msgId;
  388                         alias_skinny_port_msg(port_mesg, pip, tc, lnk, direction);
  389                         break;
  390                 }
  391                 case OPNRCVCH_ACK: {
  392                         struct OpenReceiveChannelAck *opnrcvchn_ack;
  393 
  394                         if (len < (int)sizeof(struct OpenReceiveChannelAck)) {
  395 #ifdef LIBALIAS_DEBUG
  396                                 fprintf(stderr,
  397                                     "PacketAlias/Skinny: Not a skinny packet, packet,OpnRcvChnAckMsg\n");
  398 #endif
  399                                 return;
  400                         }
  401 #ifdef LIBALIAS_DEBUG
  402                         fprintf(stderr,
  403                             "PacketAlias/Skinny: Received open rcv channel msg\n");
  404 #endif
  405                         opnrcvchn_ack = (struct OpenReceiveChannelAck *)&sd->msgId;
  406                         alias_skinny_opnrcvch_ack(la, opnrcvchn_ack, pip, tc, lnk, &lip, direction);
  407                         break;
  408                 }
  409                 case START_MEDIATX: {
  410                         struct StartMediaTransmission *startmedia_tx;
  411 
  412                         if (len < (int)sizeof(struct StartMediaTransmission)) {
  413 #ifdef LIBALIAS_DEBUG
  414                                 fprintf(stderr,
  415                                     "PacketAlias/Skinny: Not a skinny packet,StartMediaTx Message\n");
  416 #endif
  417                                 return;
  418                         }
  419                         if (lip == -1) {
  420 #ifdef LIBALIAS_DEBUG
  421                                 fprintf(stderr,
  422                                     "PacketAlias/Skinny: received a"
  423                                     " packet,StartMediaTx Message before"
  424                                     " packet,OpnRcvChnAckMsg\n"
  425 #endif
  426                                 return;
  427                         }
  428 
  429 #ifdef LIBALIAS_DEBUG
  430                         fprintf(stderr,
  431                             "PacketAlias/Skinny: Received start media trans msg\n");
  432 #endif
  433                         startmedia_tx = (struct StartMediaTransmission *)&sd->msgId;
  434                         alias_skinny_startmedia(startmedia_tx, pip, tc, lnk, lip, direction);
  435                         break;
  436                 }
  437                 default:
  438                         break;
  439                 }
  440                 /* Place the pointer at the next message in the packet. */
  441                 dlen -= len + (skinny_hdr_len - sizeof(msgId));
  442                 sd = (struct skinny_header *)(((char *)&sd->msgId) + len);
  443         }
  444 }
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FreeBSD/Linux Kernel Cross Reference sys/netinet/libalias/alias_skinny.c

FreeBSD/Linux Kernel Cross Reference
sys/netinet/libalias/alias_skinny.c
