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      1 /*
      2  * P2P - generic helper functions
      3  * Copyright (c) 2009, Atheros Communications
      4  *
      5  * This program is free software; you can redistribute it and/or modify
      6  * it under the terms of the GNU General Public License version 2 as
      7  * published by the Free Software Foundation.
      8  *
      9  * Alternatively, this software may be distributed under the terms of BSD
     10  * license.
     11  *
     12  * See README and COPYING for more details.
     13  */
     14 
     15 #include "includes.h"
     16 
     17 #include "common.h"
     18 #include "p2p_i.h"
     19 
     20 
     21 /**
     22  * p2p_random - Generate random string for SSID and passphrase
     23  * @buf: Buffer for returning the result
     24  * @len: Number of octets to write to the buffer
     25  * Returns: 0 on success, -1 on failure
     26  *
     27  * This function generates a random string using the following character set:
     28  * 'A'-'Z', 'a'-'z', '0'-'9'.
     29  */
     30 int p2p_random(char *buf, size_t len)
     31 {
     32 	u8 val;
     33 	size_t i;
     34 	u8 letters = 'Z' - 'A' + 1;
     35 	u8 numbers = 10;
     36 
     37 	if (os_get_random((unsigned char *) buf, len))
     38 		return -1;
     39 	/* Character set: 'A'-'Z', 'a'-'z', '0'-'9' */
     40 	for (i = 0; i < len; i++) {
     41 		val = buf[i];
     42 		val %= 2 * letters + numbers;
     43 		if (val < letters)
     44 			buf[i] = 'A' + val;
     45 		else if (val < 2 * letters)
     46 			buf[i] = 'a' + (val - letters);
     47 		else
     48 			buf[i] = '0' + (val - 2 * letters);
     49 	}
     50 
     51 	return 0;
     52 }
     53 
     54 
     55 static int p2p_channel_to_freq_j4(int reg_class, int channel)
     56 {
     57 	/* Table J-4 in P802.11REVmb/D4.0 - Global operating classes */
     58 	/* TODO: more regulatory classes */
     59 	switch (reg_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_channel_to_freq - Convert channel info to frequency
    104  * @country: Country code
    105  * @reg_class: Regulatory class
    106  * @channel: Channel number
    107  * Returns: Frequency in MHz or -1 if the specified channel is unknown
    108  */
    109 int p2p_channel_to_freq(const char *country, int reg_class, int channel)
    110 {
    111 	if (country[2] == 0x04)
    112 		return p2p_channel_to_freq_j4(reg_class, channel);
    113 
    114 	/* These are mainly for backwards compatibility; to be removed */
    115 	switch (reg_class) {
    116 	case 1: /* US/1, EU/1, JP/1 = 5 GHz, channels 36,40,44,48 */
    117 		if (channel < 36 || channel > 48)
    118 			return -1;
    119 		return 5000 + 5 * channel;
    120 	case 3: /* US/3 = 5 GHz, channels 149,153,157,161 */
    121 	case 5: /* US/5 = 5 GHz, channels 149,153,157,161 */
    122 		if (channel < 149 || channel > 161)
    123 			return -1;
    124 		return 5000 + 5 * channel;
    125 	case 4: /* EU/4 = 2.407 GHz, channels 1..13 */
    126 	case 12: /* US/12 = 2.407 GHz, channels 1..11 */
    127 	case 30: /* JP/30 = 2.407 GHz, channels 1..13 */
    128 		if (channel < 1 || channel > 13)
    129 			return -1;
    130 		return 2407 + 5 * channel;
    131 	case 31: /* JP/31 = 2.414 GHz, channel 14 */
    132 		if (channel != 14)
    133 			return -1;
    134 		return 2414 + 5 * channel;
    135 	}
    136 
    137 	return -1;
    138 }
    139 
    140 
    141 /**
    142  * p2p_freq_to_channel - Convert frequency into channel info
    143  * @country: Country code
    144  * @reg_class: Buffer for returning regulatory class
    145  * @channel: Buffer for returning channel number
    146  * Returns: 0 on success, -1 if the specified frequency is unknown
    147  */
    148 int p2p_freq_to_channel(const char *country, unsigned int freq, u8 *reg_class,
    149 			u8 *channel)
    150 {
    151 	/* TODO: more operating classes */
    152 	if (freq >= 2412 && freq <= 2472) {
    153 		*reg_class = 81; /* 2.407 GHz, channels 1..13 */
    154 		*channel = (freq - 2407) / 5;
    155 		return 0;
    156 	}
    157 
    158 	if (freq == 2484) {
    159 		*reg_class = 82; /* channel 14 */
    160 		*channel = 14;
    161 		return 0;
    162 	}
    163 
    164 	if (freq >= 5180 && freq <= 5240) {
    165 		*reg_class = 115; /* 5 GHz, channels 36..48 */
    166 		*channel = (freq - 5000) / 5;
    167 		return 0;
    168 	}
    169 
    170 	if (freq >= 5745 && freq <= 5805) {
    171 		*reg_class = 124; /* 5 GHz, channels 149..161 */
    172 		*channel = (freq - 5000) / 5;
    173 		return 0;
    174 	}
    175 
    176 	return -1;
    177 }
    178 
    179 
    180 static void p2p_reg_class_intersect(const struct p2p_reg_class *a,
    181 				    const struct p2p_reg_class *b,
    182 				    struct p2p_reg_class *res)
    183 {
    184 	size_t i, j;
    185 
    186 	res->reg_class = a->reg_class;
    187 
    188 	for (i = 0; i < a->channels; i++) {
    189 		for (j = 0; j < b->channels; j++) {
    190 			if (a->channel[i] != b->channel[j])
    191 				continue;
    192 			res->channel[res->channels] = a->channel[i];
    193 			res->channels++;
    194 			if (res->channels == P2P_MAX_REG_CLASS_CHANNELS)
    195 				return;
    196 		}
    197 	}
    198 }
    199 
    200 
    201 /**
    202  * p2p_channels_intersect - Intersection of supported channel lists
    203  * @a: First set of supported channels
    204  * @b: Second set of supported channels
    205  * @res: Data structure for returning the intersection of support channels
    206  *
    207  * This function can be used to find a common set of supported channels. Both
    208  * input channels sets are assumed to use the same country code. If different
    209  * country codes are used, the regulatory class numbers may not be matched
    210  * correctly and results are undefined.
    211  */
    212 void p2p_channels_intersect(const struct p2p_channels *a,
    213 			    const struct p2p_channels *b,
    214 			    struct p2p_channels *res)
    215 {
    216 	size_t i, j;
    217 
    218 	os_memset(res, 0, sizeof(*res));
    219 
    220 	for (i = 0; i < a->reg_classes; i++) {
    221 		const struct p2p_reg_class *a_reg = &a->reg_class[i];
    222 		for (j = 0; j < b->reg_classes; j++) {
    223 			const struct p2p_reg_class *b_reg = &b->reg_class[j];
    224 			if (a_reg->reg_class != b_reg->reg_class)
    225 				continue;
    226 			p2p_reg_class_intersect(
    227 				a_reg, b_reg,
    228 				&res->reg_class[res->reg_classes]);
    229 			if (res->reg_class[res->reg_classes].channels) {
    230 				res->reg_classes++;
    231 				if (res->reg_classes == P2P_MAX_REG_CLASSES)
    232 					return;
    233 			}
    234 		}
    235 	}
    236 }
    237 
    238 
    239 /**
    240  * p2p_channels_includes - Check whether a channel is included in the list
    241  * @channels: List of supported channels
    242  * @reg_class: Regulatory class of the channel to search
    243  * @channel: Channel number of the channel to search
    244  * Returns: 1 if channel was found or 0 if not
    245  */
    246 int p2p_channels_includes(const struct p2p_channels *channels, u8 reg_class,
    247 			  u8 channel)
    248 {
    249 	size_t i, j;
    250 	for (i = 0; i < channels->reg_classes; i++) {
    251 		const struct p2p_reg_class *reg = &channels->reg_class[i];
    252 		if (reg->reg_class != reg_class)
    253 			continue;
    254 		for (j = 0; j < reg->channels; j++) {
    255 			if (reg->channel[j] == channel)
    256 				return 1;
    257 		}
    258 	}
    259 	return 0;
    260 }
    261 
    262 
    263 int p2p_supported_freq(struct p2p_data *p2p, unsigned int freq)
    264 {
    265 	u8 op_reg_class, op_channel;
    266 	if (p2p_freq_to_channel(p2p->cfg->country, freq,
    267 				&op_reg_class, &op_channel) < 0)
    268 		return 0;
    269 	return p2p_channels_includes(&p2p->cfg->channels, op_reg_class,
    270 				     op_channel);
    271 }
    272