net/x25/x25_facilities.c

   1 /*
   2  *      X.25 Packet Layer release 002
   3  *
   4  *      This is ALPHA test software. This code may break your machine,
   5  *      randomly fail to work with new releases, misbehave and/or generally
   6  *      screw up. It might even work.
   7  *
   8  *      This code REQUIRES 2.1.15 or higher
   9  *
  10  *      This module:
  11  *              This module is free software; you can redistribute it and/or
  12  *              modify it under the terms of the GNU General Public License
  13  *              as published by the Free Software Foundation; either version
  14  *              2 of the License, or (at your option) any later version.
  15  *
  16  *      History
  17  *      X.25 001        Split from x25_subr.c
  18  *      mar/20/00       Daniela Squassoni Disabling/enabling of facilities
  19  *                                        negotiation.
  20  *      apr/14/05       Shaun Pereira - Allow fast select with no restriction
  21  *                                      on response.
  22  */
  23
  24 #include <linux/kernel.h>
  25 #include <linux/string.h>
  26 #include <linux/skbuff.h>
  27 #include <net/sock.h>
  28 #include <net/x25.h>
  29
  30 /*
  31  * Parse a set of facilities into the facilities structures. Unrecognised
  32  *      facilities are written to the debug log file.
  33  */
  34 int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities,
  35                 struct x25_dte_facilities *dte_facs, unsigned long *vc_fac_mask)
  36 {
  37         unsigned char *p = skb->data;
  38         unsigned int len = *p++;
  39
  40         *vc_fac_mask = 0;
  41
  42         /*
  43          * The kernel knows which facilities were set on an incoming call but
  44          * currently this information is not available to userspace.  Here we
  45          * give userspace who read incoming call facilities 0 length to indicate
  46          * it wasn't set.
  47          */
  48         dte_facs->calling_len = 0;
  49         dte_facs->called_len = 0;
  50         memset(dte_facs->called_ae, '\0', sizeof(dte_facs->called_ae));
  51         memset(dte_facs->calling_ae, '\0', sizeof(dte_facs->calling_ae));
  52
  53         while (len > 0) {
  54                 switch (*p & X25_FAC_CLASS_MASK) {
  55                 case X25_FAC_CLASS_A:
  56                         switch (*p) {
  57                         case X25_FAC_REVERSE:
  58                                 if((p[1] & 0x81) == 0x81) {
  59                                         facilities->reverse = p[1] & 0x81;
  60                                         *vc_fac_mask |= X25_MASK_REVERSE;
  61                                         break;
  62                                 }
  63
  64                                 if((p[1] & 0x01) == 0x01) {
  65                                         facilities->reverse = p[1] & 0x01;
  66                                         *vc_fac_mask |= X25_MASK_REVERSE;
  67                                         break;
  68                                 }
  69
  70                                 if((p[1] & 0x80) == 0x80) {
  71                                         facilities->reverse = p[1] & 0x80;
  72                                         *vc_fac_mask |= X25_MASK_REVERSE;
  73                                         break;
  74                                 }
  75
  76                                 if(p[1] == 0x00) {
  77                                         facilities->reverse
  78                                                 = X25_DEFAULT_REVERSE;
  79                                         *vc_fac_mask |= X25_MASK_REVERSE;
  80                                         break;
  81                                 }
  82
  83                         case X25_FAC_THROUGHPUT:
  84                                 facilities->throughput = p[1];
  85                                 *vc_fac_mask |= X25_MASK_THROUGHPUT;
  86                                 break;
  87                         case X25_MARKER:
  88                                 break;
  89                         default:
  90                                 printk(KERN_DEBUG "X.25: unknown facility "
  91                                        "%02X, value %02X\n",
  92                                        p[0], p[1]);
  93                                 break;
  94                         }
  95                         p   += 2;
  96                         len -= 2;
  97                         break;
  98                 case X25_FAC_CLASS_B:
  99                         switch (*p) {
 100                         case X25_FAC_PACKET_SIZE:
 101                                 facilities->pacsize_in  = p[1];
 102                                 facilities->pacsize_out = p[2];
 103                                 *vc_fac_mask |= X25_MASK_PACKET_SIZE;
 104                                 break;
 105                         case X25_FAC_WINDOW_SIZE:
 106                                 facilities->winsize_in  = p[1];
 107                                 facilities->winsize_out = p[2];
 108                                 *vc_fac_mask |= X25_MASK_WINDOW_SIZE;
 109                                 break;
 110                         default:
 111                                 printk(KERN_DEBUG "X.25: unknown facility "
 112                                        "%02X, values %02X, %02X\n",
 113                                        p[0], p[1], p[2]);
 114                                 break;
 115                         }
 116                         p   += 3;
 117                         len -= 3;
 118                         break;
 119                 case X25_FAC_CLASS_C:
 120                         printk(KERN_DEBUG "X.25: unknown facility %02X, "
 121                                "values %02X, %02X, %02X\n",
 122                                p[0], p[1], p[2], p[3]);
 123                         p   += 4;
 124                         len -= 4;
 125                         break;
 126                 case X25_FAC_CLASS_D:
 127                         switch (*p) {
 128                         case X25_FAC_CALLING_AE:
 129                                 if (p[1] > X25_MAX_DTE_FACIL_LEN)
 130                                         break;
 131                                 dte_facs->calling_len = p[2];
 132                                 memcpy(dte_facs->calling_ae, &p[3], p[1] - 1);
 133                                 *vc_fac_mask |= X25_MASK_CALLING_AE;
 134                                 break;
 135                         case X25_FAC_CALLED_AE:
 136                                 if (p[1] > X25_MAX_DTE_FACIL_LEN)
 137                                         break;
 138                                 dte_facs->called_len = p[2];
 139                                 memcpy(dte_facs->called_ae, &p[3], p[1] - 1);
 140                                 *vc_fac_mask |= X25_MASK_CALLED_AE;
 141                                 break;
 142                         default:
 143                                 printk(KERN_DEBUG "X.25: unknown facility %02X,"
 144                                         "length %d, values %02X, %02X, "
 145                                         "%02X, %02X\n",
 146                                         p[0], p[1], p[2], p[3], p[4], p[5]);
 147                                 break;
 148                         }
 149                         len -= p[1] + 2;
 150                         p += p[1] + 2;
 151                         break;
 152                 }
 153         }
 154
 155         return p - skb->data;
 156 }
 157
 158 /*
 159  *      Create a set of facilities.
 160  */
 161 int x25_create_facilities(unsigned char *buffer,
 162                 struct x25_facilities *facilities,
 163                 struct x25_dte_facilities *dte_facs, unsigned long facil_mask)
 164 {
 165         unsigned char *p = buffer + 1;
 166         int len;
 167
 168         if (!facil_mask) {
 169                 /*
 170                  * Length of the facilities field in call_req or
 171                  * call_accept packets
 172                  */
 173                 buffer[0] = 0;
 174                 len = 1; /* 1 byte for the length field */
 175                 return len;
 176         }
 177
 178         if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) {
 179                 *p++ = X25_FAC_REVERSE;
 180                 *p++ = facilities->reverse;
 181         }
 182
 183         if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) {
 184                 *p++ = X25_FAC_THROUGHPUT;
 185                 *p++ = facilities->throughput;
 186         }
 187
 188         if ((facilities->pacsize_in || facilities->pacsize_out) &&
 189             (facil_mask & X25_MASK_PACKET_SIZE)) {
 190                 *p++ = X25_FAC_PACKET_SIZE;
 191                 *p++ = facilities->pacsize_in ? : facilities->pacsize_out;
 192                 *p++ = facilities->pacsize_out ? : facilities->pacsize_in;
 193         }
 194
 195         if ((facilities->winsize_in || facilities->winsize_out) &&
 196             (facil_mask & X25_MASK_WINDOW_SIZE)) {
 197                 *p++ = X25_FAC_WINDOW_SIZE;
 198                 *p++ = facilities->winsize_in ? : facilities->winsize_out;
 199                 *p++ = facilities->winsize_out ? : facilities->winsize_in;
 200         }
 201
 202         if (facil_mask & (X25_MASK_CALLING_AE|X25_MASK_CALLED_AE)) {
 203                 *p++ = X25_MARKER;
 204                 *p++ = X25_DTE_SERVICES;
 205         }
 206
 207         if (dte_facs->calling_len && (facil_mask & X25_MASK_CALLING_AE)) {
 208                 unsigned bytecount = (dte_facs->calling_len % 2) ?
 209                                         dte_facs->calling_len / 2 + 1 :
 210                                         dte_facs->calling_len / 2;
 211                 *p++ = X25_FAC_CALLING_AE;
 212                 *p++ = 1 + bytecount;
 213                 *p++ = dte_facs->calling_len;
 214                 memcpy(p, dte_facs->calling_ae, bytecount);
 215                 p += bytecount;
 216         }
 217
 218         if (dte_facs->called_len && (facil_mask & X25_MASK_CALLED_AE)) {
 219                 unsigned bytecount = (dte_facs->called_len % 2) ?
 220                 dte_facs->called_len / 2 + 1 :
 221                 dte_facs->called_len / 2;
 222                 *p++ = X25_FAC_CALLED_AE;
 223                 *p++ = 1 + bytecount;
 224                 *p++ = dte_facs->called_len;
 225                 memcpy(p, dte_facs->called_ae, bytecount);
 226                 p+=bytecount;
 227         }
 228
 229         len       = p - buffer;
 230         buffer[0] = len - 1;
 231
 232         return len;
 233 }
 234
 235 /*
 236  *      Try to reach a compromise on a set of facilities.
 237  *
 238  *      The only real problem is with reverse charging.
 239  */
 240 int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk,
 241                 struct x25_facilities *new, struct x25_dte_facilities *dte)
 242 {
 243         struct x25_sock *x25 = x25_sk(sk);
 244         struct x25_facilities *ours = &x25->facilities;
 245         struct x25_facilities theirs;
 246         int len;
 247
 248         memset(&theirs, 0, sizeof(theirs));
 249         memcpy(new, ours, sizeof(*new));
 250
 251         len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask);
 252
 253         /*
 254          *      They want reverse charging, we won't accept it.
 255          */
 256         if ((theirs.reverse & 0x01 ) && (ours->reverse & 0x01)) {
 257                 SOCK_DEBUG(sk, "X.25: rejecting reverse charging request\n");
 258                 return -1;
 259         }
 260
 261         new->reverse = theirs.reverse;
 262
 263         if (theirs.throughput) {
 264                 if (theirs.throughput < ours->throughput) {
 265                         SOCK_DEBUG(sk, "X.25: throughput negotiated down\n");
 266                         new->throughput = theirs.throughput;
 267                 }
 268         }
 269
 270         if (theirs.pacsize_in && theirs.pacsize_out) {
 271                 if (theirs.pacsize_in < ours->pacsize_in) {
 272                         SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down\n");
 273                         new->pacsize_in = theirs.pacsize_in;
 274                 }
 275                 if (theirs.pacsize_out < ours->pacsize_out) {
 276                         SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down\n");
 277                         new->pacsize_out = theirs.pacsize_out;
 278                 }
 279         }
 280
 281         if (theirs.winsize_in && theirs.winsize_out) {
 282                 if (theirs.winsize_in < ours->winsize_in) {
 283                         SOCK_DEBUG(sk, "X.25: window size inwards negotiated down\n");
 284                         new->winsize_in = theirs.winsize_in;
 285                 }
 286                 if (theirs.winsize_out < ours->winsize_out) {
 287                         SOCK_DEBUG(sk, "X.25: window size outwards negotiated down\n");
 288                         new->winsize_out = theirs.winsize_out;
 289                 }
 290         }
 291
 292         return len;
 293 }
 294
 295 /*
 296  *      Limit values of certain facilities according to the capability of the
 297  *      currently attached x25 link.
 298  */
 299 void x25_limit_facilities(struct x25_facilities *facilities,
 300                           struct x25_neigh *nb)
 301 {
 302
 303         if (!nb->extended) {
 304                 if (facilities->winsize_in  > 7) {
 305                         printk(KERN_DEBUG "X.25: incoming winsize limited to 7\n");
 306                         facilities->winsize_in = 7;
 307                 }
 308                 if (facilities->winsize_out > 7) {
 309                         facilities->winsize_out = 7;
 310                         printk( KERN_DEBUG "X.25: outgoing winsize limited to 7\n");
 311                 }
 312         }
 313 }