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  */
  21
  22 #include <linux/errno.h>
  23 #include <linux/types.h>
  24 #include <linux/socket.h>
  25 #include <linux/in.h>
  26 #include <linux/kernel.h>
  27 #include <linux/sched.h>
  28 #include <linux/timer.h>
  29 #include <linux/string.h>
  30 #include <linux/sockios.h>
  31 #include <linux/net.h>
  32 #include <linux/inet.h>
  33 #include <linux/netdevice.h>
  34 #include <linux/skbuff.h>
  35 #include <net/sock.h>
  36 #include <asm/system.h>
  37 #include <linux/fcntl.h>
  38 #include <linux/mm.h>
  39 #include <linux/interrupt.h>
  40 #include <net/x25.h>
  41
  42 /*
  43  *      Parse a set of facilities into the facilities structure. Unrecognised
  44  *      facilities are written to the debug log file.
  45  */
  46 int x25_parse_facilities(struct sk_buff *skb,
  47                          struct x25_facilities *facilities,
  48                          unsigned long *vc_fac_mask)
  49 {
  50         unsigned char *p = skb->data;
  51         unsigned int len = *p++;
  52
  53         *vc_fac_mask = 0;
  54
  55         while (len > 0) {
  56                 switch (*p & X25_FAC_CLASS_MASK) {
  57                 case X25_FAC_CLASS_A:
  58                         switch (*p) {
  59                         case X25_FAC_REVERSE:
  60                                 facilities->reverse = p[1] & 0x01;
  61                                 *vc_fac_mask |= X25_MASK_REVERSE;
  62                                 break;
  63                         case X25_FAC_THROUGHPUT:
  64                                 facilities->throughput = p[1];
  65                                 *vc_fac_mask |= X25_MASK_THROUGHPUT;
  66                                 break;
  67                         default:
  68                                 printk(KERN_DEBUG "X.25: unknown facility "
  69                                        "%02X, value %02X\n",
  70                                        p[0], p[1]);
  71                                 break;
  72                         }
  73                         p   += 2;
  74                         len -= 2;
  75                         break;
  76                 case X25_FAC_CLASS_B:
  77                         switch (*p) {
  78                         case X25_FAC_PACKET_SIZE:
  79                                 facilities->pacsize_in  = p[1];
  80                                 facilities->pacsize_out = p[2];
  81                                 *vc_fac_mask |= X25_MASK_PACKET_SIZE;
  82                                 break;
  83                         case X25_FAC_WINDOW_SIZE:
  84                                 facilities->winsize_in  = p[1];
  85                                 facilities->winsize_out = p[2];
  86                                 *vc_fac_mask |= X25_MASK_WINDOW_SIZE;
  87                                 break;
  88                         default:
  89                                 printk(KERN_DEBUG "X.25: unknown facility "
  90                                        "%02X, values %02X, %02X\n",
  91                                        p[0], p[1], p[2]);
  92                                 break;
  93                         }
  94                         p   += 3;
  95                         len -= 3;
  96                         break;
  97                 case X25_FAC_CLASS_C:
  98                         printk(KERN_DEBUG "X.25: unknown facility %02X, "
  99                                "values %02X, %02X, %02X\n",
 100                                p[0], p[1], p[2], p[3]);
 101                         p   += 4;
 102                         len -= 4;
 103                         break;
 104                 case X25_FAC_CLASS_D:
 105                         printk(KERN_DEBUG "X.25: unknown facility %02X, "
 106                                "length %d, values %02X, %02X, %02X, %02X\n",
 107                                p[0], p[1], p[2], p[3], p[4], p[5]);
 108                         len -= p[1] + 2;
 109                         p   += p[1] + 2;
 110                         break;
 111                 }
 112         }
 113
 114         return p - skb->data;
 115 }
 116
 117 /*
 118  *      Create a set of facilities.
 119  */
 120 int x25_create_facilities(unsigned char *buffer,
 121                           struct x25_facilities *facilities,
 122                           unsigned long facil_mask)
 123 {
 124         unsigned char *p = buffer + 1;
 125         int len;
 126
 127         if (!facil_mask) {
 128                 /*
 129                  * Length of the facilities field in call_req or
 130                  * call_accept packets
 131                  */
 132                 buffer[0] = 0;
 133                 len = 1; /* 1 byte for the length field */
 134                 return len;
 135         }
 136
 137         if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) {
 138                 *p++ = X25_FAC_REVERSE;
 139                 *p++ = !!facilities->reverse;
 140         }
 141
 142         if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) {
 143                 *p++ = X25_FAC_THROUGHPUT;
 144                 *p++ = facilities->throughput;
 145         }
 146
 147         if ((facilities->pacsize_in || facilities->pacsize_out) &&
 148             (facil_mask & X25_MASK_PACKET_SIZE)) {
 149                 *p++ = X25_FAC_PACKET_SIZE;
 150                 *p++ = facilities->pacsize_in ? : facilities->pacsize_out;
 151                 *p++ = facilities->pacsize_out ? : facilities->pacsize_in;
 152         }
 153
 154         if ((facilities->winsize_in || facilities->winsize_out) &&
 155             (facil_mask & X25_MASK_WINDOW_SIZE)) {
 156                 *p++ = X25_FAC_WINDOW_SIZE;
 157                 *p++ = facilities->winsize_in ? : facilities->winsize_out;
 158                 *p++ = facilities->winsize_out ? : facilities->winsize_in;
 159         }
 160
 161         len       = p - buffer;
 162         buffer[0] = len - 1;
 163
 164         return len;
 165 }
 166
 167 /*
 168  *      Try to reach a compromise on a set of facilities.
 169  *
 170  *      The only real problem is with reverse charging.
 171  */
 172 int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk,
 173                              struct x25_facilities *new)
 174 {
 175         struct x25_opt *x25 = x25_sk(sk);
 176         struct x25_facilities *ours = &x25->facilities;
 177         struct x25_facilities theirs;
 178         int len;
 179
 180         memset(&theirs, 0, sizeof(theirs));
 181         memcpy(new, ours, sizeof(*new));
 182
 183         len = x25_parse_facilities(skb, &theirs, &x25->vc_facil_mask);
 184
 185         /*
 186          *      They want reverse charging, we won't accept it.
 187          */
 188         if (theirs.reverse && ours->reverse) {
 189                 SOCK_DEBUG(sk, "X.25: rejecting reverse charging request");
 190                 return -1;
 191         }
 192
 193         new->reverse = theirs.reverse;
 194
 195         if (theirs.throughput) {
 196                 if (theirs.throughput < ours->throughput) {
 197                         SOCK_DEBUG(sk, "X.25: throughput negotiated down");
 198                         new->throughput = theirs.throughput;
 199                 }
 200         }
 201
 202         if (theirs.pacsize_in && theirs.pacsize_out) {
 203                 if (theirs.pacsize_in < ours->pacsize_in) {
 204                         SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down");
 205                         new->pacsize_in = theirs.pacsize_in;
 206                 }
 207                 if (theirs.pacsize_out < ours->pacsize_out) {
 208                         SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down");
 209                         new->pacsize_out = theirs.pacsize_out;
 210                 }
 211         }
 212
 213         if (theirs.winsize_in && theirs.winsize_out) {
 214                 if (theirs.winsize_in < ours->winsize_in) {
 215                         SOCK_DEBUG(sk, "X.25: window size inwards negotiated down");
 216                         new->winsize_in = theirs.winsize_in;
 217                 }
 218                 if (theirs.winsize_out < ours->winsize_out) {
 219                         SOCK_DEBUG(sk, "X.25: window size outwards negotiated down");
 220                         new->winsize_out = theirs.winsize_out;
 221                 }
 222         }
 223
 224         return len;
 225 }
 226
 227 /*
 228  *      Limit values of certain facilities according to the capability of the
 229  *      currently attached x25 link.
 230  */
 231 void x25_limit_facilities(struct x25_facilities *facilities,
 232                           struct x25_neigh *nb)
 233 {
 234
 235         if (!nb->extended) {
 236                 if (facilities->winsize_in  > 7) {
 237                         printk(KERN_DEBUG "X.25: incoming winsize limited to 7\n");
 238                         facilities->winsize_in = 7;
 239                 }
 240                 if (facilities->winsize_out > 7) {
 241                         facilities->winsize_out = 7;
 242                         printk( KERN_DEBUG "X.25: outgoing winsize limited to 7\n");
 243                 }
 244         }
 245 }