P2P: Move random channel selection into a helper function

The new p2p_channel_select() function can be re-used to implement
random channel selection from a set of operating classes in all
places that need such functonality.

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

src/p2p/p2p_go_neg.c

@@ -348,6 +348,7 @@ void p2p_reselect_channel(struct p2p_data *p2p,
 	int freq;
 	u8 op_reg_class, op_channel;
 	unsigned int i;
+	const int op_classes_5ghz[] = { 115, 124, 0 };
 
 	if (p2p->own_freq_preference > 0 &&
 	    p2p_freq_to_channel(p2p->own_freq_preference,
@@ -438,24 +439,11 @@ void p2p_reselect_channel(struct p2p_data *p2p,
 	}
 
 	/* Prefer a 5 GHz channel */
-	for (i = 0; i < intersection->reg_classes; i++) {
-		struct p2p_reg_class *c = &intersection->reg_class[i];
-		if ((c->reg_class == 115 || c->reg_class == 124) &&
-		    c->channels) {
-			unsigned int r;
-
-			/*
-			 * Pick one of the available channels in the operating
-			 * class at random.
-			 */
-			os_get_random((u8 *) &r, sizeof(r));
-			r %= c->channels;
-			p2p_dbg(p2p, "Pick possible 5 GHz channel (op_class %u channel %u) from intersection",
-				c->reg_class, c->channel[r]);
-			p2p->op_reg_class = c->reg_class;
-			p2p->op_channel = c->channel[r];
-			return;
-		}
+	if (p2p_channel_select(intersection, op_classes_5ghz,
+			       &p2p->op_reg_class, &p2p->op_channel) == 0) {
+		p2p_dbg(p2p, "Pick possible 5 GHz channel (op_class %u channel %u) from intersection",
+			p2p->op_reg_class, p2p->op_channel);
+		return;
 	}
 
 	/*

src/p2p/p2p_i.h

@@ -581,6 +581,8 @@ int p2p_channels_includes(const struct p2p_channels *channels, u8 reg_class,
 			  u8 channel);
 void p2p_channels_dump(struct p2p_data *p2p, const char *title,
 		       const struct p2p_channels *chan);
+int p2p_channel_select(struct p2p_channels *chans, const int *classes,
+		       u8 *op_class, u8 *op_channel);
 
 /* p2p_parse.c */
 int p2p_parse_p2p_ie(const struct wpabuf *buf, struct p2p_message *msg);

src/p2p/p2p_utils.c

@@ -439,3 +439,36 @@ void p2p_channels_dump(struct p2p_data *p2p, const char *title,
 
 	p2p_dbg(p2p, "%s:%s", title, buf);
 }
+
+
+int p2p_channel_select(struct p2p_channels *chans, const int *classes,
+		       u8 *op_class, u8 *op_channel)
+{
+	unsigned int i, j, r;
+
+	for (i = 0; i < chans->reg_classes; i++) {
+		struct p2p_reg_class *c = &chans->reg_class[i];
+
+		if (c->channels == 0)
+			continue;
+
+		for (j = 0; classes[j]; j++) {
+			if (c->reg_class == classes[j])
+				break;
+		}
+		if (!classes[j])
+			continue;
+
+		/*
+		 * Pick one of the available channels in the operating class at
+		 * random.
+		 */
+		os_get_random((u8 *) &r, sizeof(r));
+		r %= c->channels;
+		*op_class = c->reg_class;
+		*op_channel = c->channel[r];
+		return 0;
+	}
+
+	return -1;
+}