P2P: Add support for preferred channel list

p2p_pref_chan configuration parameter can now be used to set the
list of preferred channel for P2P GO Negotiation. This will be used
in the priority order if the peer does not support the channel we
are trying to use as the GO (configured operating channel or the
best 2.4 GHz/5 GHz channel) for the case where a forced channel is
not used.

p2p_pref_chan=<op class:channel>,...

For example:
p2p_pref_chan=81:1,81:2,81:3,81:4,81:5,81:6

This would configure 2.4 GHz channels 1-6 as the preferred ones with
channel 1 the most preferred option.

These configuration parameters can be set in wpa_supplicant.conf and
dynamically updated with "wpa_cli set <param> <value>".

Signed-hostap: Jouni Malinen <jouni@qca.qualcomm.com>

src/p2p/p2p.c

@@ -2212,6 +2212,16 @@ struct p2p_data * p2p_init(const struct p2p_config *cfg)
 		p2p->cfg->model_number = os_strdup(cfg->model_number);
 	if (cfg->serial_number)
 		p2p->cfg->serial_number = os_strdup(cfg->serial_number);
+	if (cfg->pref_chan) {
+		p2p->cfg->pref_chan = os_malloc(cfg->num_pref_chan *
+						sizeof(struct p2p_channel));
+		if (p2p->cfg->pref_chan) {
+			os_memcpy(p2p->cfg->pref_chan, cfg->pref_chan,
+				  cfg->num_pref_chan *
+				  sizeof(struct p2p_channel));
+		} else
+			p2p->cfg->num_pref_chan = 0;
+	}
 
 	p2p->min_disc_int = 1;
 	p2p->max_disc_int = 3;
@@ -2246,6 +2256,7 @@ void p2p_deinit(struct p2p_data *p2p)
 	os_free(p2p->cfg->model_name);
 	os_free(p2p->cfg->model_number);
 	os_free(p2p->cfg->serial_number);
+	os_free(p2p->cfg->pref_chan);
 	os_free(p2p->groups);
 	wpabuf_free(p2p->sd_resp);
 	os_free(p2p->after_scan_tx);
@@ -3701,6 +3712,28 @@ int p2p_set_oper_channel(struct p2p_data *p2p, u8 op_reg_class, u8 op_channel,
 }
 
 
+int p2p_set_pref_chan(struct p2p_data *p2p, unsigned int num_pref_chan,
+		      const struct p2p_channel *pref_chan)
+{
+	struct p2p_channel *n;
+
+	if (pref_chan) {
+		n = os_malloc(num_pref_chan * sizeof(struct p2p_channel));
+		if (n == NULL)
+			return -1;
+		os_memcpy(n, pref_chan,
+			  num_pref_chan * sizeof(struct p2p_channel));
+	} else
+		n = NULL;
+
+	os_free(p2p->cfg->pref_chan);
+	p2p->cfg->pref_chan = n;
+	p2p->cfg->num_pref_chan = num_pref_chan;
+
+	return 0;
+}
+
+
 int p2p_get_interface_addr(struct p2p_data *p2p, const u8 *dev_addr,
 			   u8 *iface_addr)
 {

src/p2p/p2p.h

@@ -218,6 +218,11 @@ enum p2p_prov_disc_status {
 	P2P_PROV_DISC_REJECTED,
 };
 
+struct p2p_channel {
+	u8 op_class;
+	u8 chan;
+};
+
 /**
  * struct p2p_config - P2P configuration
  *
@@ -264,6 +269,16 @@ struct p2p_config {
 	 */
 	struct p2p_channels channels;
 
+	/**
+	 * num_pref_chan - Number of pref_chan entries
+	 */
+	unsigned int num_pref_chan;
+
+	/**
+	 * pref_chan - Preferred channels for GO Negotiation
+	 */
+	struct p2p_channel *pref_chan;
+
 	/**
 	 * pri_dev_type - Primary Device Type (see WPS)
 	 */
@@ -1608,6 +1623,16 @@ int p2p_add_wps_vendor_extension(struct p2p_data *p2p,
 int p2p_set_oper_channel(struct p2p_data *p2p, u8 op_reg_class, u8 op_channel,
 			 int cfg_op_channel);
 
+/**
+ * p2p_set_pref_chan - Set P2P preferred channel list
+ * @p2p: P2P module context from p2p_init()
+ * @num_pref_chan: Number of entries in pref_chan list
+ * @pref_chan: Preferred channels or %NULL to remove preferences
+ * Returns: 0 on success, -1 on failure
+ */
+int p2p_set_pref_chan(struct p2p_data *p2p, unsigned int num_pref_chan,
+		      const struct p2p_channel *pref_chan);
+
 /**
  * p2p_in_progress - Check whether a P2P operation is progress
  * @p2p: P2P module context from p2p_init()

src/p2p/p2p_go_neg.c

@@ -296,6 +296,7 @@ static void p2p_reselect_channel(struct p2p_data *p2p,
 	struct p2p_reg_class *cl;
 	int freq;
 	u8 op_reg_class, op_channel;
+	unsigned int i;
 
 	wpa_msg(p2p->cfg->msg_ctx, MSG_DEBUG, "P2P: Selected operating "
 		"channel (reg_class %u channel %u) not acceptable to the "
@@ -328,6 +329,21 @@ static void p2p_reselect_channel(struct p2p_data *p2p,
 		return;
 	}
 
+	/* Select channel with highest preference if the peer supports it */
+	for (i = 0; p2p->cfg->pref_chan && i < p2p->cfg->num_pref_chan; i++) {
+		if (p2p_channels_includes(intersection,
+					  p2p->cfg->pref_chan[i].op_class,
+					  p2p->cfg->pref_chan[i].chan)) {
+			p2p->op_reg_class = p2p->cfg->pref_chan[i].op_class;
+			p2p->op_channel = p2p->cfg->pref_chan[i].chan;
+			wpa_msg(p2p->cfg->msg_ctx, MSG_DEBUG, "P2P: Pick "
+				"highest preferred chnnel (op_class %u "
+				"channel %u) from intersection",
+				p2p->op_reg_class, p2p->op_channel);
+			return;
+		}
+	}
+
 	/*
 	 * Fall back to whatever is included in the channel intersection since
 	 * no better options seems to be available.

wpa_supplicant/config.c

@@ -13,6 +13,7 @@
 #include "crypto/sha1.h"
 #include "rsn_supp/wpa.h"
 #include "eap_peer/eap.h"
+#include "p2p/p2p.h"
 #include "config.h"
 
 
@@ -1849,6 +1850,7 @@ void wpa_config_free(struct wpa_config *config)
 	os_free(config->config_methods);
 	os_free(config->p2p_ssid_postfix);
 	os_free(config->pssid);
+	os_free(config->p2p_pref_chan);
 	os_free(config);
 }
 
@@ -2692,6 +2694,55 @@ static int wpa_config_process_sec_device_type(
 	config->num_sec_device_types++;
 	return 0;
 }
+
+
+static int wpa_config_process_p2p_pref_chan(
+	const struct global_parse_data *data,
+	struct wpa_config *config, int line, const char *pos)
+{
+	struct p2p_channel *pref = NULL, *n;
+	unsigned int num = 0;
+	const char *pos2;
+	u8 op_class, chan;
+
+	/* format: class:chan,class:chan,... */
+
+	while (*pos) {
+		op_class = atoi(pos);
+		pos2 = os_strchr(pos, ':');
+		if (pos2 == NULL)
+			goto fail;
+		pos2++;
+		chan = atoi(pos2);
+
+		n = os_realloc(pref, (num + 1) * sizeof(struct p2p_channel));
+		if (n == NULL)
+			goto fail;
+		pref = n;
+		pref[num].op_class = op_class;
+		pref[num].chan = chan;
+		num++;
+
+		pos = os_strchr(pos2, ',');
+		if (pos == NULL)
+			break;
+		pos++;
+	}
+
+	os_free(config->p2p_pref_chan);
+	config->p2p_pref_chan = pref;
+	config->num_p2p_pref_chan = num;
+	wpa_hexdump(MSG_DEBUG, "P2P: Preferred class/channel pairs",
+		    (u8 *) config->p2p_pref_chan,
+		    config->num_p2p_pref_chan * sizeof(struct p2p_channel));
+
+	return 0;
+
+fail:
+	os_free(pref);
+	wpa_printf(MSG_ERROR, "Line %d: Invalid p2p_pref_chan list", line);
+	return -1;
+}
 #endif /* CONFIG_P2P */
 
 
@@ -2768,6 +2819,7 @@ static const struct global_parse_data global_fields[] = {
 	{ INT_RANGE(persistent_reconnect, 0, 1), 0 },
 	{ INT_RANGE(p2p_intra_bss, 0, 1), CFG_CHANGED_P2P_INTRA_BSS },
 	{ INT(p2p_group_idle), 0 },
+	{ FUNC(p2p_pref_chan), CFG_CHANGED_P2P_PREF_CHAN },
 #endif /* CONFIG_P2P */
 	{ FUNC(country), CFG_CHANGED_COUNTRY },
 	{ INT(bss_max_count), 0 },

wpa_supplicant/config.h

@@ -164,6 +164,7 @@ struct wpa_cred {
 #define CFG_CHANGED_VENDOR_EXTENSION BIT(10)
 #define CFG_CHANGED_P2P_LISTEN_CHANNEL BIT(11)
 #define CFG_CHANGED_P2P_OPER_CHANNEL BIT(12)
+#define CFG_CHANGED_P2P_PREF_CHAN BIT(13)
 
 /**
  * struct wpa_config - wpa_supplicant configuration data
@@ -503,6 +504,8 @@ struct wpa_config {
 	char *p2p_ssid_postfix;
 	int persistent_reconnect;
 	int p2p_intra_bss;
+	unsigned int num_p2p_pref_chan;
+	struct p2p_channel *p2p_pref_chan;
 
 #define MAX_WPS_VENDOR_EXT 10
 	/**

wpa_supplicant/config_file.c

@@ -16,6 +16,7 @@
 #include "config.h"
 #include "base64.h"
 #include "uuid.h"
+#include "p2p/p2p.h"
 
 
 /**
@@ -790,6 +791,16 @@ static void wpa_config_write_global(FILE *f, struct wpa_config *config)
 		fprintf(f, "p2p_intra_bss=%u\n", config->p2p_intra_bss);
 	if (config->p2p_group_idle)
 		fprintf(f, "p2p_group_idle=%u\n", config->p2p_group_idle);
+	if (config->p2p_pref_chan) {
+		unsigned int i;
+		fprintf(f, "p2p_pref_chan=");
+		for (i = 0; i < config->num_p2p_pref_chan; i++) {
+			fprintf(f, "%s%u:%u", i > 0 ? "," : "",
+				config->p2p_pref_chan[i].op_class,
+				config->p2p_pref_chan[i].chan);
+		}
+		fprintf(f, "\n");
+	}
 #endif /* CONFIG_P2P */
 	if (config->country[0] && config->country[1]) {
 		fprintf(f, "country=%c%c\n",

wpa_supplicant/p2p_supplicant.c

@@ -4151,6 +4151,14 @@ void wpas_p2p_update_config(struct wpa_supplicant *wpa_s)
 			wpa_printf(MSG_ERROR, "P2P: Own oper channel update "
 				   "failed: %d", ret);
 	}
+
+	if (wpa_s->conf->changed_parameters & CFG_CHANGED_P2P_PREF_CHAN) {
+		if (p2p_set_pref_chan(p2p, wpa_s->conf->num_p2p_pref_chan,
+				      wpa_s->conf->p2p_pref_chan) < 0) {
+			wpa_printf(MSG_ERROR, "P2P: Preferred channel list "
+				   "update failed");
+		}
+	}
 }