src/p2p/p2p_utils.c

   1 /*
   2  * P2P - generic helper functions
   3  * Copyright (c) 2009, Atheros Communications
   4  *
   5  * This software may be distributed under the terms of the BSD license.
   6  * See README for more details.
   7  */
   8
   9 #include "includes.h"
  10
  11 #include "common.h"
  12 #include "p2p_i.h"
  13
  14
  15 /**
  16  * p2p_random - Generate random string for SSID and passphrase
  17  * @buf: Buffer for returning the result
  18  * @len: Number of octets to write to the buffer
  19  * Returns: 0 on success, -1 on failure
  20  *
  21  * This function generates a random string using the following character set:
  22  * 'A'-'Z', 'a'-'z', '0'-'9'.
  23  */
  24 int p2p_random(char *buf, size_t len)
  25 {
  26         u8 val;
  27         size_t i;
  28         u8 letters = 'Z' - 'A' + 1;
  29         u8 numbers = 10;
  30
  31         if (os_get_random((unsigned char *) buf, len))
  32                 return -1;
  33         /* Character set: 'A'-'Z', 'a'-'z', '0'-'9' */
  34         for (i = 0; i < len; i++) {
  35                 val = buf[i];
  36                 val %= 2 * letters + numbers;
  37                 if (val < letters)
  38                         buf[i] = 'A' + val;
  39                 else if (val < 2 * letters)
  40                         buf[i] = 'a' + (val - letters);
  41                 else
  42                         buf[i] = '0' + (val - 2 * letters);
  43         }
  44
  45         return 0;
  46 }
  47
  48
  49 /**
  50  * p2p_channel_to_freq - Convert channel info to frequency
  51  * @op_class: Operating class
  52  * @channel: Channel number
  53  * Returns: Frequency in MHz or -1 if the specified channel is unknown
  54  */
  55 int p2p_channel_to_freq(int op_class, int channel)
  56 {
  57         /* Table E-4 in IEEE Std 802.11-2012 - Global operating classes */
  58         /* TODO: more operating classes */
  59         switch (op_class) {
  60         case 81:
  61                 /* channels 1..13 */
  62                 if (channel < 1 || channel > 13)
  63                         return -1;
  64                 return 2407 + 5 * channel;
  65         case 82:
  66                 /* channel 14 */
  67                 if (channel != 14)
  68                         return -1;
  69                 return 2414 + 5 * channel;
  70         case 83: /* channels 1..9; 40 MHz */
  71         case 84: /* channels 5..13; 40 MHz */
  72                 if (channel < 1 || channel > 13)
  73                         return -1;
  74                 return 2407 + 5 * channel;
  75         case 115: /* channels 36,40,44,48; indoor only */
  76         case 118: /* channels 52,56,60,64; dfs */
  77                 if (channel < 36 || channel > 64)
  78                         return -1;
  79                 return 5000 + 5 * channel;
  80         case 124: /* channels 149,153,157,161 */
  81         case 125: /* channels 149,153,157,161,165,169 */
  82                 if (channel < 149 || channel > 161)
  83                         return -1;
  84                 return 5000 + 5 * channel;
  85         case 116: /* channels 36,44; 40 MHz; indoor only */
  86         case 117: /* channels 40,48; 40 MHz; indoor only */
  87         case 119: /* channels 52,60; 40 MHz; dfs */
  88         case 120: /* channels 56,64; 40 MHz; dfs */
  89                 if (channel < 36 || channel > 64)
  90                         return -1;
  91                 return 5000 + 5 * channel;
  92         case 126: /* channels 149,157; 40 MHz */
  93         case 127: /* channels 153,161; 40 MHz */
  94                 if (channel < 149 || channel > 161)
  95                         return -1;
  96                 return 5000 + 5 * channel;
  97         }
  98         return -1;
  99 }
 100
 101
 102 /**
 103  * p2p_freq_to_channel - Convert frequency into channel info
 104  * @op_class: Buffer for returning operating class
 105  * @channel: Buffer for returning channel number
 106  * Returns: 0 on success, -1 if the specified frequency is unknown
 107  */
 108 int p2p_freq_to_channel(unsigned int freq, u8 *op_class, u8 *channel)
 109 {
 110         /* TODO: more operating classes */
 111         if (freq >= 2412 && freq <= 2472) {
 112                 *op_class = 81; /* 2.407 GHz, channels 1..13 */
 113                 *channel = (freq - 2407) / 5;
 114                 return 0;
 115         }
 116
 117         if (freq == 2484) {
 118                 *op_class = 82; /* channel 14 */
 119                 *channel = 14;
 120                 return 0;
 121         }
 122
 123         if (freq >= 5180 && freq <= 5240) {
 124                 *op_class = 115; /* 5 GHz, channels 36..48 */
 125                 *channel = (freq - 5000) / 5;
 126                 return 0;
 127         }
 128
 129         if (freq >= 5745 && freq <= 5805) {
 130                 *op_class = 124; /* 5 GHz, channels 149..161 */
 131                 *channel = (freq - 5000) / 5;
 132                 return 0;
 133         }
 134
 135         return -1;
 136 }
 137
 138
 139 static void p2p_reg_class_intersect(const struct p2p_reg_class *a,
 140                                     const struct p2p_reg_class *b,
 141                                     struct p2p_reg_class *res)
 142 {
 143         size_t i, j;
 144
 145         res->reg_class = a->reg_class;
 146
 147         for (i = 0; i < a->channels; i++) {
 148                 for (j = 0; j < b->channels; j++) {
 149                         if (a->channel[i] != b->channel[j])
 150                                 continue;
 151                         res->channel[res->channels] = a->channel[i];
 152                         res->channels++;
 153                         if (res->channels == P2P_MAX_REG_CLASS_CHANNELS)
 154                                 return;
 155                 }
 156         }
 157 }
 158
 159
 160 /**
 161  * p2p_channels_intersect - Intersection of supported channel lists
 162  * @a: First set of supported channels
 163  * @b: Second set of supported channels
 164  * @res: Data structure for returning the intersection of support channels
 165  *
 166  * This function can be used to find a common set of supported channels. Both
 167  * input channels sets are assumed to use the same country code. If different
 168  * country codes are used, the regulatory class numbers may not be matched
 169  * correctly and results are undefined.
 170  */
 171 void p2p_channels_intersect(const struct p2p_channels *a,
 172                             const struct p2p_channels *b,
 173                             struct p2p_channels *res)
 174 {
 175         size_t i, j;
 176
 177         os_memset(res, 0, sizeof(*res));
 178
 179         for (i = 0; i < a->reg_classes; i++) {
 180                 const struct p2p_reg_class *a_reg = &a->reg_class[i];
 181                 for (j = 0; j < b->reg_classes; j++) {
 182                         const struct p2p_reg_class *b_reg = &b->reg_class[j];
 183                         if (a_reg->reg_class != b_reg->reg_class)
 184                                 continue;
 185                         p2p_reg_class_intersect(
 186                                 a_reg, b_reg,
 187                                 &res->reg_class[res->reg_classes]);
 188                         if (res->reg_class[res->reg_classes].channels) {
 189                                 res->reg_classes++;
 190                                 if (res->reg_classes == P2P_MAX_REG_CLASSES)
 191                                         return;
 192                         }
 193                 }
 194         }
 195 }
 196
 197
 198 /**
 199  * p2p_channels_includes - Check whether a channel is included in the list
 200  * @channels: List of supported channels
 201  * @reg_class: Regulatory class of the channel to search
 202  * @channel: Channel number of the channel to search
 203  * Returns: 1 if channel was found or 0 if not
 204  */
 205 int p2p_channels_includes(const struct p2p_channels *channels, u8 reg_class,
 206                           u8 channel)
 207 {
 208         size_t i, j;
 209         for (i = 0; i < channels->reg_classes; i++) {
 210                 const struct p2p_reg_class *reg = &channels->reg_class[i];
 211                 if (reg->reg_class != reg_class)
 212                         continue;
 213                 for (j = 0; j < reg->channels; j++) {
 214                         if (reg->channel[j] == channel)
 215                                 return 1;
 216                 }
 217         }
 218         return 0;
 219 }
 220
 221
 222 int p2p_channels_includes_freq(const struct p2p_channels *channels,
 223                                unsigned int freq)
 224 {
 225         size_t i, j;
 226         for (i = 0; i < channels->reg_classes; i++) {
 227                 const struct p2p_reg_class *reg = &channels->reg_class[i];
 228                 for (j = 0; j < reg->channels; j++) {
 229                         if (p2p_channel_to_freq(reg->reg_class,
 230                                                 reg->channel[j]) == (int) freq)
 231                                 return 1;
 232                 }
 233         }
 234         return 0;
 235 }
 236
 237
 238 int p2p_supported_freq(struct p2p_data *p2p, unsigned int freq)
 239 {
 240         u8 op_reg_class, op_channel;
 241         if (p2p_freq_to_channel(freq, &op_reg_class, &op_channel) < 0)
 242                 return 0;
 243         return p2p_channels_includes(&p2p->cfg->channels, op_reg_class,
 244                                      op_channel);
 245 }
 246
 247
 248 unsigned int p2p_get_pref_freq(struct p2p_data *p2p,
 249                                const struct p2p_channels *channels)
 250 {
 251         unsigned int i;
 252         int freq = 0;
 253
 254         if (channels == NULL) {
 255                 if (p2p->cfg->num_pref_chan) {
 256                         freq = p2p_channel_to_freq(
 257                                 p2p->cfg->pref_chan[0].op_class,
 258                                 p2p->cfg->pref_chan[0].chan);
 259                         if (freq < 0)
 260                                 freq = 0;
 261                 }
 262                 return freq;
 263         }
 264
 265         for (i = 0; p2p->cfg->pref_chan && i < p2p->cfg->num_pref_chan; i++) {
 266                 freq = p2p_channel_to_freq(p2p->cfg->pref_chan[i].op_class,
 267                                            p2p->cfg->pref_chan[i].chan);
 268                 if (p2p_channels_includes_freq(channels, freq))
 269                         return freq;
 270         }
 271
 272         return 0;
 273 }