p2p_utils.c revision 3bdda0eea1d423ad6feac810ceee94d75761d667 
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 */
24int 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 */
55int 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 */
108int 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		if ((freq - 2407) % 5)
113			return -1;
114
115		*op_class = 81; /* 2.407 GHz, channels 1..13 */
116		*channel = (freq - 2407) / 5;
117		return 0;
118	}
119
120	if (freq == 2484) {
121		*op_class = 82; /* channel 14 */
122		*channel = 14;
123		return 0;
124	}
125
126	if (freq >= 5180 && freq <= 5240) {
127		if ((freq - 5000) % 5)
128			return -1;
129
130		*op_class = 115; /* 5 GHz, channels 36..48 */
131		*channel = (freq - 5000) / 5;
132		return 0;
133	}
134
135	if (freq >= 5745 && freq <= 5805) {
136		if ((freq - 5000) % 5)
137			return -1;
138
139		*op_class = 124; /* 5 GHz, channels 149..161 */
140		*channel = (freq - 5000) / 5;
141		return 0;
142	}
143
144	return -1;
145}
146
147
148static void p2p_reg_class_intersect(const struct p2p_reg_class *a,
149				    const struct p2p_reg_class *b,
150				    struct p2p_reg_class *res)
151{
152	size_t i, j;
153
154	res->reg_class = a->reg_class;
155
156	for (i = 0; i < a->channels; i++) {
157		for (j = 0; j < b->channels; j++) {
158			if (a->channel[i] != b->channel[j])
159				continue;
160			res->channel[res->channels] = a->channel[i];
161			res->channels++;
162			if (res->channels == P2P_MAX_REG_CLASS_CHANNELS)
163				return;
164		}
165	}
166}
167
168
169/**
170 * p2p_channels_intersect - Intersection of supported channel lists
171 * @a: First set of supported channels
172 * @b: Second set of supported channels
173 * @res: Data structure for returning the intersection of support channels
174 *
175 * This function can be used to find a common set of supported channels. Both
176 * input channels sets are assumed to use the same country code. If different
177 * country codes are used, the regulatory class numbers may not be matched
178 * correctly and results are undefined.
179 */
180void p2p_channels_intersect(const struct p2p_channels *a,
181			    const struct p2p_channels *b,
182			    struct p2p_channels *res)
183{
184	size_t i, j;
185
186	os_memset(res, 0, sizeof(*res));
187
188	for (i = 0; i < a->reg_classes; i++) {
189		const struct p2p_reg_class *a_reg = &a->reg_class[i];
190		for (j = 0; j < b->reg_classes; j++) {
191			const struct p2p_reg_class *b_reg = &b->reg_class[j];
192			if (a_reg->reg_class != b_reg->reg_class)
193				continue;
194			p2p_reg_class_intersect(
195				a_reg, b_reg,
196				&res->reg_class[res->reg_classes]);
197			if (res->reg_class[res->reg_classes].channels) {
198				res->reg_classes++;
199				if (res->reg_classes == P2P_MAX_REG_CLASSES)
200					return;
201			}
202		}
203	}
204}
205
206
207/**
208 * p2p_channels_includes - Check whether a channel is included in the list
209 * @channels: List of supported channels
210 * @reg_class: Regulatory class of the channel to search
211 * @channel: Channel number of the channel to search
212 * Returns: 1 if channel was found or 0 if not
213 */
214int p2p_channels_includes(const struct p2p_channels *channels, u8 reg_class,
215			  u8 channel)
216{
217	size_t i, j;
218	for (i = 0; i < channels->reg_classes; i++) {
219		const struct p2p_reg_class *reg = &channels->reg_class[i];
220		if (reg->reg_class != reg_class)
221			continue;
222		for (j = 0; j < reg->channels; j++) {
223			if (reg->channel[j] == channel)
224				return 1;
225		}
226	}
227	return 0;
228}
229
230
231int p2p_channels_includes_freq(const struct p2p_channels *channels,
232			       unsigned int freq)
233{
234	size_t i, j;
235	for (i = 0; i < channels->reg_classes; i++) {
236		const struct p2p_reg_class *reg = &channels->reg_class[i];
237		for (j = 0; j < reg->channels; j++) {
238			if (p2p_channel_to_freq(reg->reg_class,
239						reg->channel[j]) == (int) freq)
240				return 1;
241		}
242	}
243	return 0;
244}
245
246
247int p2p_supported_freq(struct p2p_data *p2p, unsigned int freq)
248{
249	u8 op_reg_class, op_channel;
250
251#ifdef ANDROID_P2P
252	if ((freq >= 5170 && freq < 5745) &&
253	    (os_strncasecmp(p2p->cfg->country, "US", 2) == 0))
254		return 0;
255#endif
256	if (p2p_freq_to_channel(freq, &op_reg_class, &op_channel) < 0)
257		return 0;
258	return p2p_channels_includes(&p2p->cfg->channels, op_reg_class,
259				     op_channel);
260}
261
262
263unsigned int p2p_get_pref_freq(struct p2p_data *p2p,
264			       const struct p2p_channels *channels)
265{
266	unsigned int i;
267	int freq = 0;
268
269	if (channels == NULL) {
270		if (p2p->cfg->num_pref_chan) {
271			freq = p2p_channel_to_freq(
272				p2p->cfg->pref_chan[0].op_class,
273				p2p->cfg->pref_chan[0].chan);
274			if (freq < 0)
275				freq = 0;
276		}
277		return freq;
278	}
279
280	for (i = 0; p2p->cfg->pref_chan && i < p2p->cfg->num_pref_chan; i++) {
281		freq = p2p_channel_to_freq(p2p->cfg->pref_chan[i].op_class,
282					   p2p->cfg->pref_chan[i].chan);
283		if (p2p_channels_includes_freq(channels, freq))
284			return freq;
285	}
286
287	return 0;
288}
289