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                         switch (*p) {
  65                         case X25_FAC_REVERSE:
  66                                 if((p[1] & 0x81) == 0x81) {
  67                                         facilities->reverse = p[1] & 0x81;
  68                                         *vc_fac_mask |= X25_MASK_REVERSE;
  69                                         break;
  70                                 }
  71
  72                                 if((p[1] & 0x01) == 0x01) {
  73                                         facilities->reverse = p[1] & 0x01;
  74                                         *vc_fac_mask |= X25_MASK_REVERSE;
  75                                         break;
  76                                 }
  77
  78                                 if((p[1] & 0x80) == 0x80) {
  79                                         facilities->reverse = p[1] & 0x80;
  80                                         *vc_fac_mask |= X25_MASK_REVERSE;
  81                                         break;
  82                                 }
  83
  84                                 if(p[1] == 0x00) {
  85                                         facilities->reverse
  86                                                 = X25_DEFAULT_REVERSE;
  87                                         *vc_fac_mask |= X25_MASK_REVERSE;
  88                                         break;
  89                                 }
  90
  91                         case X25_FAC_THROUGHPUT:
  92                                 facilities->throughput = p[1];
  93                                 *vc_fac_mask |= X25_MASK_THROUGHPUT;
  94                                 break;
  95                         case X25_MARKER:
  96                                 break;
  97                         default:
  98                                 printk(KERN_DEBUG "X.25: unknown facility "
  99                                        "%02X, value %02X\n",
 100                                        p[0], p[1]);
 101                                 break;
 102                         }
 103                         p   += 2;
 104                         len -= 2;
 105                         break;
 106                 case X25_FAC_CLASS_B:
 107                         switch (*p) {
 108                         case X25_FAC_PACKET_SIZE:
 109                                 facilities->pacsize_in  = p[1];
 110                                 facilities->pacsize_out = p[2];
 111                                 *vc_fac_mask |= X25_MASK_PACKET_SIZE;
 112                                 break;
 113                         case X25_FAC_WINDOW_SIZE:
 114                                 facilities->winsize_in  = p[1];
 115                                 facilities->winsize_out = p[2];
 116                                 *vc_fac_mask |= X25_MASK_WINDOW_SIZE;
 117                                 break;
 118                         default:
 119                                 printk(KERN_DEBUG "X.25: unknown facility "
 120                                        "%02X, values %02X, %02X\n",
 121                                        p[0], p[1], p[2]);
 122                                 break;
 123                         }
 124                         p   += 3;
 125                         len -= 3;
 126                         break;
 127                 case X25_FAC_CLASS_C:
 128                         printk(KERN_DEBUG "X.25: unknown facility %02X, "
 129                                "values %02X, %02X, %02X\n",
 130                                p[0], p[1], p[2], p[3]);
 131                         p   += 4;
 132                         len -= 4;
 133                         break;
 134                 case X25_FAC_CLASS_D:
 135                         switch (*p) {
 136                         case X25_FAC_CALLING_AE:
 137                                 if (p[1] > X25_MAX_DTE_FACIL_LEN)
 138                                         break;
 139                                 dte_facs->calling_len = p[2];
 140                                 memcpy(dte_facs->calling_ae, &p[3], p[1] - 1);
 141                                 *vc_fac_mask |= X25_MASK_CALLING_AE;
 142                                 break;
 143                         case X25_FAC_CALLED_AE:
 144                                 if (p[1] > X25_MAX_DTE_FACIL_LEN)
 145                                         break;
 146                                 dte_facs->called_len = p[2];
 147                                 memcpy(dte_facs->called_ae, &p[3], p[1] - 1);
 148                                 *vc_fac_mask |= X25_MASK_CALLED_AE;
 149                                 break;
 150                         default:
 151                                 printk(KERN_DEBUG "X.25: unknown facility %02X,"
 152                                         "length %d, values %02X, %02X, "
 153                                         "%02X, %02X\n",
 154                                         p[0], p[1], p[2], p[3], p[4], p[5]);
 155                                 break;
 156                         }
 157                         len -= p[1] + 2;
 158                         p += p[1] + 2;
 159                         break;
 160                 }
 161         }
 162
 163         return p - skb->data;
 164 }
 165
 166 /*
 167  *      Create a set of facilities.
 168  */
 169 int x25_create_facilities(unsigned char *buffer,
 170                 struct x25_facilities *facilities,
 171                 struct x25_dte_facilities *dte_facs, unsigned long facil_mask)
 172 {
 173         unsigned char *p = buffer + 1;
 174         int len;
 175
 176         if (!facil_mask) {
 177                 /*
 178                  * Length of the facilities field in call_req or
 179                  * call_accept packets
 180                  */
 181                 buffer[0] = 0;
 182                 len = 1; /* 1 byte for the length field */
 183                 return len;
 184         }
 185
 186         if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) {
 187                 *p++ = X25_FAC_REVERSE;
 188                 *p++ = facilities->reverse;
 189         }
 190
 191         if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) {
 192                 *p++ = X25_FAC_THROUGHPUT;
 193                 *p++ = facilities->throughput;
 194         }
 195
 196         if ((facilities->pacsize_in || facilities->pacsize_out) &&
 197             (facil_mask & X25_MASK_PACKET_SIZE)) {
 198                 *p++ = X25_FAC_PACKET_SIZE;
 199                 *p++ = facilities->pacsize_in ? : facilities->pacsize_out;
 200                 *p++ = facilities->pacsize_out ? : facilities->pacsize_in;
 201         }
 202
 203         if ((facilities->winsize_in || facilities->winsize_out) &&
 204             (facil_mask & X25_MASK_WINDOW_SIZE)) {
 205                 *p++ = X25_FAC_WINDOW_SIZE;
 206                 *p++ = facilities->winsize_in ? : facilities->winsize_out;
 207                 *p++ = facilities->winsize_out ? : facilities->winsize_in;
 208         }
 209
 210         if (facil_mask & (X25_MASK_CALLING_AE|X25_MASK_CALLED_AE)) {
 211                 *p++ = X25_MARKER;
 212                 *p++ = X25_DTE_SERVICES;
 213         }
 214
 215         if (dte_facs->calling_len && (facil_mask & X25_MASK_CALLING_AE)) {
 216                 unsigned bytecount = (dte_facs->calling_len + 1) >> 1;
 217                 *p++ = X25_FAC_CALLING_AE;
 218                 *p++ = 1 + bytecount;
 219                 *p++ = dte_facs->calling_len;
 220                 memcpy(p, dte_facs->calling_ae, bytecount);
 221                 p += bytecount;
 222         }
 223
 224         if (dte_facs->called_len && (facil_mask & X25_MASK_CALLED_AE)) {
 225                 unsigned bytecount = (dte_facs->called_len % 2) ?
 226                 dte_facs->called_len / 2 + 1 :
 227                 dte_facs->called_len / 2;
 228                 *p++ = X25_FAC_CALLED_AE;
 229                 *p++ = 1 + bytecount;
 230                 *p++ = dte_facs->called_len;
 231                 memcpy(p, dte_facs->called_ae, bytecount);
 232                 p+=bytecount;
 233         }
 234
 235         len       = p - buffer;
 236         buffer[0] = len - 1;
 237
 238         return len;
 239 }
 240
 241 /*
 242  *      Try to reach a compromise on a set of facilities.
 243  *
 244  *      The only real problem is with reverse charging.
 245  */
 246 int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk,
 247                 struct x25_facilities *new, struct x25_dte_facilities *dte)
 248 {
 249         struct x25_sock *x25 = x25_sk(sk);
 250         struct x25_facilities *ours = &x25->facilities;
 251         struct x25_facilities theirs;
 252         int len;
 253
 254         memset(&theirs, 0, sizeof(theirs));
 255         memcpy(new, ours, sizeof(*new));
 256
 257         len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask);
 258         if (len < 0)
 259                 return len;
 260
 261         /*
 262          *      They want reverse charging, we won't accept it.
 263          */
 264         if ((theirs.reverse & 0x01 ) && (ours->reverse & 0x01)) {
 265                 SOCK_DEBUG(sk, "X.25: rejecting reverse charging request\n");
 266                 return -1;
 267         }
 268
 269         new->reverse = theirs.reverse;
 270
 271         if (theirs.throughput) {
 272                 int theirs_in =  theirs.throughput & 0x0f;
 273                 int theirs_out = theirs.throughput & 0xf0;
 274                 int ours_in  = ours->throughput & 0x0f;
 275                 int ours_out = ours->throughput & 0xf0;
 276                 if (!ours_in || theirs_in < ours_in) {
 277                         SOCK_DEBUG(sk, "X.25: inbound throughput negotiated\n");
 278                         new->throughput = (new->throughput & 0xf0) | theirs_in;
 279                 }
 280                 if (!ours_out || theirs_out < ours_out) {
 281                         SOCK_DEBUG(sk,
 282                                 "X.25: outbound throughput negotiated\n");
 283                         new->throughput = (new->throughput & 0x0f) | theirs_out;
 284                 }
 285         }
 286
 287         if (theirs.pacsize_in && theirs.pacsize_out) {
 288                 if (theirs.pacsize_in < ours->pacsize_in) {
 289                         SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down\n");
 290                         new->pacsize_in = theirs.pacsize_in;
 291                 }
 292                 if (theirs.pacsize_out < ours->pacsize_out) {
 293                         SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down\n");
 294                         new->pacsize_out = theirs.pacsize_out;
 295                 }
 296         }
 297
 298         if (theirs.winsize_in && theirs.winsize_out) {
 299                 if (theirs.winsize_in < ours->winsize_in) {
 300                         SOCK_DEBUG(sk, "X.25: window size inwards negotiated down\n");
 301                         new->winsize_in = theirs.winsize_in;
 302                 }
 303                 if (theirs.winsize_out < ours->winsize_out) {
 304                         SOCK_DEBUG(sk, "X.25: window size outwards negotiated down\n");
 305                         new->winsize_out = theirs.winsize_out;
 306                 }
 307         }
 308
 309         return len;
 310 }
 311
 312 /*
 313  *      Limit values of certain facilities according to the capability of the
 314  *      currently attached x25 link.
 315  */
 316 void x25_limit_facilities(struct x25_facilities *facilities,
 317                           struct x25_neigh *nb)
 318 {
 319
 320         if (!nb->extended) {
 321                 if (facilities->winsize_in  > 7) {
 322                         printk(KERN_DEBUG "X.25: incoming winsize limited to 7\n");
 323                         facilities->winsize_in = 7;
 324                 }
 325                 if (facilities->winsize_out > 7) {
 326                         facilities->winsize_out = 7;
 327                         printk( KERN_DEBUG "X.25: outgoing winsize limited to 7\n");
 328                 }
 329         }
 330 }