LXR linux/net/x25/x25

   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 */
  34int 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 */
 161int 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 + 1) >> 1;
 209                *p++ = X25_FAC_CALLING_AE;
 210                *p++ = 1 + bytecount;
 211                *p++ = dte_facs->calling_len;
 212                memcpy(p, dte_facs->calling_ae, bytecount);
 213                p += bytecount;
 214        }
 215
 216        if (dte_facs->called_len && (facil_mask & X25_MASK_CALLED_AE)) {
 217                unsigned bytecount = (dte_facs->called_len % 2) ?
 218                dte_facs->called_len / 2 + 1 :
 219                dte_facs->called_len / 2;
 220                *p++ = X25_FAC_CALLED_AE;
 221                *p++ = 1 + bytecount;
 222                *p++ = dte_facs->called_len;
 223                memcpy(p, dte_facs->called_ae, bytecount);
 224                p+=bytecount;
 225        }
 226
 227        len       = p - buffer;
 228        buffer[0] = len - 1;
 229
 230        return len;
 231}
 232
 233/*
 234 *      Try to reach a compromise on a set of facilities.
 235 *
 236 *      The only real problem is with reverse charging.
 237 */
 238int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk,
 239                struct x25_facilities *new, struct x25_dte_facilities *dte)
 240{
 241        struct x25_sock *x25 = x25_sk(sk);
 242        struct x25_facilities *ours = &x25->facilities;
 243        struct x25_facilities theirs;
 244        int len;
 245
 246        memset(&theirs, 0, sizeof(theirs));
 247        memcpy(new, ours, sizeof(*new));
 248
 249        len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask);
 250
 251        /*
 252         *      They want reverse charging, we won't accept it.
 253         */
 254        if ((theirs.reverse & 0x01 ) && (ours->reverse & 0x01)) {
 255                SOCK_DEBUG(sk, "X.25: rejecting reverse charging request\n");
 256                return -1;
 257        }
 258
 259        new->reverse = theirs.reverse;
 260
 261        if (theirs.throughput) {
 262                if (theirs.throughput < ours->throughput) {
 263                        SOCK_DEBUG(sk, "X.25: throughput negotiated down\n");
 264                        new->throughput = theirs.throughput;
 265                }
 266        }
 267
 268        if (theirs.pacsize_in && theirs.pacsize_out) {
 269                if (theirs.pacsize_in < ours->pacsize_in) {
 270                        SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down\n");
 271                        new->pacsize_in = theirs.pacsize_in;
 272                }
 273                if (theirs.pacsize_out < ours->pacsize_out) {
 274                        SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down\n");
 275                        new->pacsize_out = theirs.pacsize_out;
 276                }
 277        }
 278
 279        if (theirs.winsize_in && theirs.winsize_out) {
 280                if (theirs.winsize_in < ours->winsize_in) {
 281                        SOCK_DEBUG(sk, "X.25: window size inwards negotiated down\n");
 282                        new->winsize_in = theirs.winsize_in;
 283                }
 284                if (theirs.winsize_out < ours->winsize_out) {
 285                        SOCK_DEBUG(sk, "X.25: window size outwards negotiated down\n");
 286                        new->winsize_out = theirs.winsize_out;
 287                }
 288        }
 289
 290        return len;
 291}
 292
 293/*
 294 *      Limit values of certain facilities according to the capability of the
 295 *      currently attached x25 link.
 296 */
 297void x25_limit_facilities(struct x25_facilities *facilities,
 298                          struct x25_neigh *nb)
 299{
 300
 301        if (!nb->extended) {
 302                if (facilities->winsize_in  > 7) {
 303                        printk(KERN_DEBUG "X.25: incoming winsize limited to 7\n");
 304                        facilities->winsize_in = 7;
 305                }
 306                if (facilities->winsize_out > 7) {
 307                        facilities->winsize_out = 7;
 308                        printk( KERN_DEBUG "X.25: outgoing winsize limited to 7\n");
 309                }
 310        }
 311}
 312