net/ipv4/ip_masq_cuseeme.c

   1 /*
   2  *              IP_MASQ_FTP CUSeeMe masquerading module
   3  *
   4  *
   5  * Version:     @(#)$Id: ip_masq_cuseeme.c,v 1.4 1998/10/06 04:48:57 davem Exp $
   6  *
   7  * Author:      Richard Lynch
   8  *
   9  *
  10  * Fixes:
  11  *      Richard Lynch           :       Updated patch to conform to new module
  12  *                                      specifications
  13  *      Nigel Metheringham      :       Multiple port support
  14  *      Michael Owings          :       Fixed broken init code
  15  *                                      Added code to update inbound
  16  *                                      packets with correct local addresses.
  17  *                                      Fixes audio and "chat" problems
  18  *                                      Thanx to the CU-SeeMe Consortium for
  19  *                                      technical docs
  20  *      Steven Clarke           :       Small changes for 2.1
  21  *
  22  *
  23  *
  24  *      This program is free software; you can redistribute it and/or
  25  *      modify it under the terms of the GNU General Public License
  26  *      as published by the Free Software Foundation; either version
  27  *      2 of the License, or (at your option) any later version.
  28  *
  29  * Multiple Port Support
  30  *      The helper can be made to handle up to MAX_MASQ_APP_PORTS (normally 12)
  31  *      with the port numbers being defined at module load time.  The module
  32  *      uses the symbol "ports" to define a list of monitored ports, which can
  33  *      be specified on the insmod command line as
  34  *              ports=x1,x2,x3...
  35  *      where x[n] are integer port numbers.  This option can be put into
  36  *      /etc/conf.modules (or /etc/modules.conf depending on your config)
  37  *      where modload will pick it up should you use modload to load your
  38  *      modules.
  39  *
  40  */
  41
  42 #include <linux/config.h>
  43 #include <linux/module.h>
  44 #include <asm/system.h>
  45 #include <linux/types.h>
  46 #include <linux/kernel.h>
  47 #include <linux/skbuff.h>
  48 #include <linux/in.h>
  49 #include <linux/ip.h>
  50 #include <linux/init.h>
  51 #include <net/protocol.h>
  52 #include <net/udp.h>
  53
  54 /* #define IP_MASQ_NDEBUG */
  55 #include <net/ip_masq.h>
  56
  57 #pragma pack(1)
  58 /* CU-SeeMe Data Header */
  59 typedef struct {
  60         u_short         dest_family;
  61         u_short         dest_port;
  62         u_long          dest_addr;
  63         short           family;
  64         u_short         port;
  65         u_long          addr;
  66         u_long          seq;
  67         u_short         msg;
  68         u_short         data_type;
  69         u_short         packet_len;
  70 } cu_header;
  71
  72 /* Open Continue Header */
  73 typedef struct  {
  74         cu_header       cu_head;
  75         u_short         client_count; /* Number of client info structs */
  76         u_long          seq_no;
  77         char            user_name[20];
  78         char            stuff[4]; /* flags,  version stuff,  etc */
  79 }oc_header;
  80
  81 /* client info structures */
  82 typedef struct {
  83         u_long          address; /* Client address */
  84         char            stuff[8]; /* Flags, pruning bitfield,  packet counts etc */
  85 } client_info;
  86 #pragma pack()
  87
  88 /*
  89  * List of ports (up to MAX_MASQ_APP_PORTS) to be handled by helper
  90  * First port is set to the default port.
  91  */
  92 static int ports[MAX_MASQ_APP_PORTS] = {7648}; /* I rely on the trailing items being set to zero */
  93 struct ip_masq_app *masq_incarnations[MAX_MASQ_APP_PORTS];
  94
  95 /*
  96  *     Debug level
  97  */
  98 #ifdef CONFIG_IP_MASQ_DEBUG
  99 static int debug=0;
 100 MODULE_PARM(debug, "i");
 101 #endif
 102
 103 MODULE_PARM(ports, "1-" __MODULE_STRING(MAX_MASQ_APP_PORTS) "i");
 104
 105 static int
 106 masq_cuseeme_init_1 (struct ip_masq_app *mapp, struct ip_masq *ms)
 107 {
 108         MOD_INC_USE_COUNT;
 109         return 0;
 110 }
 111
 112 static int
 113 masq_cuseeme_done_1 (struct ip_masq_app *mapp, struct ip_masq *ms)
 114 {
 115         MOD_DEC_USE_COUNT;
 116         return 0;
 117 }
 118
 119 int
 120 masq_cuseeme_out (struct ip_masq_app *mapp, struct ip_masq *ms, struct sk_buff **skb_p, __u32 maddr)
 121 {
 122         struct sk_buff *skb = *skb_p;
 123         struct iphdr *iph = skb->nh.iph;
 124         struct udphdr *uh = (struct udphdr *)&(((char *)iph)[iph->ihl*4]);
 125         cu_header *cu_head;
 126         char *data=(char *)&uh[1];
 127
 128         if (skb->len - ((unsigned char *) data - skb->h.raw) >= sizeof(cu_header))
 129         {
 130                 cu_head         = (cu_header *) data;
 131                 /* cu_head->port   = ms->mport; */
 132                 if( cu_head->addr )
 133                 cu_head->addr = (u_long) maddr;
 134                 if(ntohs(cu_head->data_type) == 257)
 135                         IP_MASQ_DEBUG(1-debug, "Sending talk packet!\n");
 136         }
 137         return 0;
 138 }
 139
 140 int
 141 masq_cuseeme_in (struct ip_masq_app *mapp, struct ip_masq *ms, struct sk_buff **skb_p, __u32 maddr)
 142 {
 143         struct sk_buff *skb = *skb_p;
 144         struct iphdr *iph = skb->nh.iph;
 145         struct udphdr *uh = (struct udphdr *)&(((char *)iph)[iph->ihl*4]);
 146         cu_header *cu_head;
 147         oc_header       *oc;
 148         client_info     *ci;
 149         char *data=(char *)&uh[1];
 150         u_short len = skb->len - ((unsigned char *) data - skb->h.raw);
 151         int             i, off;
 152
 153         if (len >= sizeof(cu_header))
 154         {
 155                 cu_head         = (cu_header *) data;
 156                 if(cu_head->dest_addr) /* Correct destination address */
 157                         cu_head->dest_addr = (u_long) ms->saddr;
 158                 if(ntohs(cu_head->data_type)==101 && len > sizeof(oc_header))
 159                 {
 160                         oc = (oc_header * ) data;
 161                         /* Spin (grovel) thru client_info structs till we find our own */
 162                         off=sizeof(oc_header);
 163                         for(i=0;
 164                             (i < oc->client_count && off+sizeof(client_info) <= len);
 165                             i++)
 166                         {
 167                                 ci=(client_info *)(data+off);
 168                                 if(ci->address==(u_long) maddr)
 169                                 {
 170                                         /* Update w/ our real ip address and exit */
 171                                         ci->address = (u_long) ms->saddr;
 172                                         break;
 173                                 }
 174                                 else
 175                                    off+=sizeof(client_info);
 176                         }
 177                 }
 178         }
 179         return 0;
 180 }
 181
 182 struct ip_masq_app ip_masq_cuseeme = {
 183         NULL,                   /* next */
 184         "cuseeme",
 185         0,                      /* type */
 186         0,                      /* n_attach */
 187         masq_cuseeme_init_1,    /* ip_masq_init_1 */
 188         masq_cuseeme_done_1,    /* ip_masq_done_1 */
 189         masq_cuseeme_out,       /* pkt_out */
 190         masq_cuseeme_in         /* pkt_in */
 191 };
 192
 193
 194 /*
 195  *      ip_masq_cuseeme initialization
 196  */
 197
 198 __initfunc(int ip_masq_cuseeme_init(void))
 199 {
 200         int i, j;
 201
 202         for (i=0; (i<MAX_MASQ_APP_PORTS); i++) {
 203                 if (ports[i]) {
 204                         if ((masq_incarnations[i] = kmalloc(sizeof(struct ip_masq_app),
 205                                                             GFP_KERNEL)) == NULL)
 206                                 return -ENOMEM;
 207                         memcpy(masq_incarnations[i], &ip_masq_cuseeme, sizeof(struct ip_masq_app));
 208                         if ((j = register_ip_masq_app(masq_incarnations[i],
 209                                                       IPPROTO_UDP,
 210                                                       ports[i]))) {
 211                                 return j;
 212                         }
 213 #if DEBUG_CONFIG_IP_MASQ_CUSEEME
 214                         IP_MASQ_DEBUG(1-debug, "CuSeeMe: loaded support on port[%d] = %d\n",
 215                                i, ports[i]);
 216 #endif
 217                 } else {
 218                         /* To be safe, force the incarnation table entry to NULL */
 219                         masq_incarnations[i] = NULL;
 220                 }
 221         }
 222         return 0;
 223 }
 224
 225 /*
 226  *      ip_masq_cuseeme fin.
 227  */
 228
 229 int ip_masq_cuseeme_done(void)
 230 {
 231         int i, j, k;
 232
 233         k=0;
 234         for (i=0; (i<MAX_MASQ_APP_PORTS); i++) {
 235                 if (masq_incarnations[i]) {
 236                         if ((j = unregister_ip_masq_app(masq_incarnations[i]))) {
 237                                 k = j;
 238                         } else {
 239                                 kfree(masq_incarnations[i]);
 240                                 masq_incarnations[i] = NULL;
 241                                 IP_MASQ_DEBUG(1-debug, "CuSeeMe: unloaded support on port[%d] = %d\n", i, ports[i]);
 242                         }
 243                 }
 244         }
 245         return k;
 246 }
 247
 248 #ifdef MODULE
 249 EXPORT_NO_SYMBOLS;
 250
 251 int init_module(void)
 252 {
 253         if (ip_masq_cuseeme_init() != 0)
 254                 return -EIO;
 255         return 0;
 256 }
 257
 258 void cleanup_module(void)
 259 {
 260         if (ip_masq_cuseeme_done() != 0)
 261                 IP_MASQ_DEBUG(1-debug, "ip_masq_cuseeme: can't remove module");
 262 }
 263
 264 #endif /* MODULE */