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;
  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         if (skb->len < 1)
  54                 return 0;
  55
  56         len = *p++;
  57
  58         if (len >= skb->len)
  59                 return -1;
  60
  61         while (len > 0) {
  62                 switch (*p & X25_FAC_CLASS_MASK) {
  63                 case X25_FAC_CLASS_A:
  64                         if (len < 2)
  65                                 return 0;
  66                         switch (*p) {
  67                         case X25_FAC_REVERSE:
  68                                 if((p[1] & 0x81) == 0x81) {
  69                                         facilities->reverse = p[1] & 0x81;
  70                                         *vc_fac_mask |= X25_MASK_REVERSE;
  71                                         break;
  72                                 }
  73
  74                                 if((p[1] & 0x01) == 0x01) {
  75                                         facilities->reverse = p[1] & 0x01;
  76                                         *vc_fac_mask |= X25_MASK_REVERSE;
  77                                         break;
  78                                 }
  79
  80                                 if((p[1] & 0x80) == 0x80) {
  81                                         facilities->reverse = p[1] & 0x80;
  82                                         *vc_fac_mask |= X25_MASK_REVERSE;
  83                                         break;
  84                                 }
  85
  86                                 if(p[1] == 0x00) {
  87                                         facilities->reverse
  88                                                 = X25_DEFAULT_REVERSE;
  89                                         *vc_fac_mask |= X25_MASK_REVERSE;
  90                                         break;
  91                                 }
  92
  93                         case X25_FAC_THROUGHPUT:
  94                                 facilities->throughput = p[1];
  95                                 *vc_fac_mask |= X25_MASK_THROUGHPUT;
  96                                 break;
  97                         case X25_MARKER:
  98                                 break;
  99                         default:
 100                                 printk(KERN_DEBUG "X.25: unknown facility "
 101                                        "%02X, value %02X\n",
 102                                        p[0], p[1]);
 103                                 break;
 104                         }
 105                         p   += 2;
 106                         len -= 2;
 107                         break;
 108                 case X25_FAC_CLASS_B:
 109                         if (len < 3)
 110                                 return 0;
 111                         switch (*p) {
 112                         case X25_FAC_PACKET_SIZE:
 113                                 facilities->pacsize_in  = p[1];
 114                                 facilities->pacsize_out = p[2];
 115                                 *vc_fac_mask |= X25_MASK_PACKET_SIZE;
 116                                 break;
 117                         case X25_FAC_WINDOW_SIZE:
 118                                 facilities->winsize_in  = p[1];
 119                                 facilities->winsize_out = p[2];
 120                                 *vc_fac_mask |= X25_MASK_WINDOW_SIZE;
 121                                 break;
 122                         default:
 123                                 printk(KERN_DEBUG "X.25: unknown facility "
 124                                        "%02X, values %02X, %02X\n",
 125                                        p[0], p[1], p[2]);
 126                                 break;
 127                         }
 128                         p   += 3;
 129                         len -= 3;
 130                         break;
 131                 case X25_FAC_CLASS_C:
 132                         if (len < 4)
 133                                 return 0;
 134                         printk(KERN_DEBUG "X.25: unknown facility %02X, "
 135                                "values %02X, %02X, %02X\n",
 136                                p[0], p[1], p[2], p[3]);
 137                         p   += 4;
 138                         len -= 4;
 139                         break;
 140                 case X25_FAC_CLASS_D:
 141                         if (len < p[1] + 2)
 142                                 return 0;
 143                         switch (*p) {
 144                         case X25_FAC_CALLING_AE:
 145                                 if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1)
 146                                         return 0;
 147                                 dte_facs->calling_len = p[2];
 148                                 memcpy(dte_facs->calling_ae, &p[3], p[1] - 1);
 149                                 *vc_fac_mask |= X25_MASK_CALLING_AE;
 150                                 break;
 151                         case X25_FAC_CALLED_AE:
 152                                 if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1)
 153                                         return 0;
 154                                 dte_facs->called_len = p[2];
 155                                 memcpy(dte_facs->called_ae, &p[3], p[1] - 1);
 156                                 *vc_fac_mask |= X25_MASK_CALLED_AE;
 157                                 break;
 158                         default:
 159                                 printk(KERN_DEBUG "X.25: unknown facility %02X,"
 160                                         "length %d\n", p[0], p[1]);
 161                                 break;
 162                         }
 163                         len -= p[1] + 2;
 164                         p += p[1] + 2;
 165                         break;
 166                 }
 167         }
 168
 169         return p - skb->data;
 170 }
 171
 172 /*
 173  *      Create a set of facilities.
 174  */
 175 int x25_create_facilities(unsigned char *buffer,
 176                 struct x25_facilities *facilities,
 177                 struct x25_dte_facilities *dte_facs, unsigned long facil_mask)
 178 {
 179         unsigned char *p = buffer + 1;
 180         int len;
 181
 182         if (!facil_mask) {
 183                 /*
 184                  * Length of the facilities field in call_req or
 185                  * call_accept packets
 186                  */
 187                 buffer[0] = 0;
 188                 len = 1; /* 1 byte for the length field */
 189                 return len;
 190         }
 191
 192         if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) {
 193                 *p++ = X25_FAC_REVERSE;
 194                 *p++ = facilities->reverse;
 195         }
 196
 197         if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) {
 198                 *p++ = X25_FAC_THROUGHPUT;
 199                 *p++ = facilities->throughput;
 200         }
 201
 202         if ((facilities->pacsize_in || facilities->pacsize_out) &&
 203             (facil_mask & X25_MASK_PACKET_SIZE)) {
 204                 *p++ = X25_FAC_PACKET_SIZE;
 205                 *p++ = facilities->pacsize_in ? : facilities->pacsize_out;
 206                 *p++ = facilities->pacsize_out ? : facilities->pacsize_in;
 207         }
 208
 209         if ((facilities->winsize_in || facilities->winsize_out) &&
 210             (facil_mask & X25_MASK_WINDOW_SIZE)) {
 211                 *p++ = X25_FAC_WINDOW_SIZE;
 212                 *p++ = facilities->winsize_in ? : facilities->winsize_out;
 213                 *p++ = facilities->winsize_out ? : facilities->winsize_in;
 214         }
 215
 216         if (facil_mask & (X25_MASK_CALLING_AE|X25_MASK_CALLED_AE)) {
 217                 *p++ = X25_MARKER;
 218                 *p++ = X25_DTE_SERVICES;
 219         }
 220
 221         if (dte_facs->calling_len && (facil_mask & X25_MASK_CALLING_AE)) {
 222                 unsigned bytecount = (dte_facs->calling_len + 1) >> 1;
 223                 *p++ = X25_FAC_CALLING_AE;
 224                 *p++ = 1 + bytecount;
 225                 *p++ = dte_facs->calling_len;
 226                 memcpy(p, dte_facs->calling_ae, bytecount);
 227                 p += bytecount;
 228         }
 229
 230         if (dte_facs->called_len && (facil_mask & X25_MASK_CALLED_AE)) {
 231                 unsigned bytecount = (dte_facs->called_len % 2) ?
 232                 dte_facs->called_len / 2 + 1 :
 233                 dte_facs->called_len / 2;
 234                 *p++ = X25_FAC_CALLED_AE;
 235                 *p++ = 1 + bytecount;
 236                 *p++ = dte_facs->called_len;
 237                 memcpy(p, dte_facs->called_ae, bytecount);
 238                 p+=bytecount;
 239         }
 240
 241         len       = p - buffer;
 242         buffer[0] = len - 1;
 243
 244         return len;
 245 }
 246
 247 /*
 248  *      Try to reach a compromise on a set of facilities.
 249  *
 250  *      The only real problem is with reverse charging.
 251  */
 252 int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk,
 253                 struct x25_facilities *new, struct x25_dte_facilities *dte)
 254 {
 255         struct x25_sock *x25 = x25_sk(sk);
 256         struct x25_facilities *ours = &x25->facilities;
 257         struct x25_facilities theirs;
 258         int len;
 259
 260         memset(&theirs, 0, sizeof(theirs));
 261         memcpy(new, ours, sizeof(*new));
 262
 263         len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask);
 264         if (len < 0)
 265                 return len;
 266
 267         /*
 268          *      They want reverse charging, we won't accept it.
 269          */
 270         if ((theirs.reverse & 0x01 ) && (ours->reverse & 0x01)) {
 271                 SOCK_DEBUG(sk, "X.25: rejecting reverse charging request\n");
 272                 return -1;
 273         }
 274
 275         new->reverse = theirs.reverse;
 276
 277         if (theirs.throughput) {
 278                 int theirs_in =  theirs.throughput & 0x0f;
 279                 int theirs_out = theirs.throughput & 0xf0;
 280                 int ours_in  = ours->throughput & 0x0f;
 281                 int ours_out = ours->throughput & 0xf0;
 282                 if (!ours_in || theirs_in < ours_in) {
 283                         SOCK_DEBUG(sk, "X.25: inbound throughput negotiated\n");
 284                         new->throughput = (new->throughput & 0xf0) | theirs_in;
 285                 }
 286                 if (!ours_out || theirs_out < ours_out) {
 287                         SOCK_DEBUG(sk,
 288                                 "X.25: outbound throughput negotiated\n");
 289                         new->throughput = (new->throughput & 0x0f) | theirs_out;
 290                 }
 291         }
 292
 293         if (theirs.pacsize_in && theirs.pacsize_out) {
 294                 if (theirs.pacsize_in < ours->pacsize_in) {
 295                         SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down\n");
 296                         new->pacsize_in = theirs.pacsize_in;
 297                 }
 298                 if (theirs.pacsize_out < ours->pacsize_out) {
 299                         SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down\n");
 300                         new->pacsize_out = theirs.pacsize_out;
 301                 }
 302         }
 303
 304         if (theirs.winsize_in && theirs.winsize_out) {
 305                 if (theirs.winsize_in < ours->winsize_in) {
 306                         SOCK_DEBUG(sk, "X.25: window size inwards negotiated down\n");
 307                         new->winsize_in = theirs.winsize_in;
 308                 }
 309                 if (theirs.winsize_out < ours->winsize_out) {
 310                         SOCK_DEBUG(sk, "X.25: window size outwards negotiated down\n");
 311                         new->winsize_out = theirs.winsize_out;
 312                 }
 313         }
 314
 315         return len;
 316 }
 317
 318 /*
 319  *      Limit values of certain facilities according to the capability of the
 320  *      currently attached x25 link.
 321  */
 322 void x25_limit_facilities(struct x25_facilities *facilities,
 323                           struct x25_neigh *nb)
 324 {
 325
 326         if (!nb->extended) {
 327                 if (facilities->winsize_in  > 7) {
 328                         printk(KERN_DEBUG "X.25: incoming winsize limited to 7\n");
 329                         facilities->winsize_in = 7;
 330                 }
 331                 if (facilities->winsize_out > 7) {
 332                         facilities->winsize_out = 7;
 333                         printk( KERN_DEBUG "X.25: outgoing winsize limited to 7\n");
 334                 }
 335         }
 336 }