wiphy: Add freq set constrain API

src/scan.c

@@ -1725,6 +1725,23 @@ void scan_freq_set_foreach(const struct scan_freq_set *freqs,
 	}
 }
 
+void scan_freq_set_constrain(struct scan_freq_set *set,
+					const struct scan_freq_set *constraint)
+{
+	struct l_uintset *intersection;
+
+	intersection = l_uintset_intersect(constraint->channels_5ghz,
+							set->channels_5ghz);
+	if (!intersection)
+		/* This shouldn't ever be the case. */
+		return;
+
+	l_uintset_free(set->channels_5ghz);
+	set->channels_5ghz = intersection;
+
+	set->channels_2ghz &= constraint->channels_2ghz;
+}
+
 bool scan_init(struct l_genl_family *in)
 {
 	const struct l_settings *config = iwd_get_config();

src/scan.h

@@ -126,6 +126,8 @@ void scan_freq_set_foreach(const struct scan_freq_set *freqs,
 				scan_freq_set_func_t func, void *user_data);
 void scan_freq_set_merge(struct scan_freq_set *to,
 					const struct scan_freq_set *from);
+void scan_freq_set_constrain(struct scan_freq_set *set,
+					const struct scan_freq_set *constraint);
 
 bool scan_ifindex_add(uint32_t ifindex);
 bool scan_ifindex_remove(uint32_t ifindex);

src/wiphy.c

@@ -306,6 +306,18 @@ bool wiphy_supports_adhoc_rsn(struct wiphy *wiphy)
 	return wiphy->support_adhoc_rsn;
 }
 
+bool wiphy_constrain_freq_set(const struct wiphy *wiphy,
+						struct scan_freq_set *set)
+{
+	scan_freq_set_constrain(set, wiphy->supported_freqs);
+
+	if (!scan_freq_set_get_bands(set))
+		/* The set is empty. */
+		return false;
+
+	return true;
+}
+
 static char **wiphy_get_supported_iftypes(struct wiphy *wiphy, uint16_t mask)
 {
 	uint16_t supported_mask = wiphy->supported_iftypes & mask;

src/wiphy.h

@@ -25,6 +25,7 @@
 
 struct wiphy;
 struct scan_bss;
+struct scan_freq_set;
 
 enum wiphy_state_watch_event {
 	WIPHY_STATE_WATCH_EVENT_POWERED,
@@ -50,6 +51,9 @@ struct wiphy *wiphy_create(uint32_t wiphy_id, const char *name);
 bool wiphy_destroy(struct wiphy *wiphy);
 void wiphy_update_from_genl(struct wiphy *wiphy, struct l_genl_msg *msg);
 
+bool wiphy_constrain_freq_set(const struct wiphy *wiphy,
+						struct scan_freq_set *set);
+
 const char *wiphy_get_path(struct wiphy *wiphy);
 uint32_t wiphy_get_supported_bands(struct wiphy *wiphy);
 const struct scan_freq_set *wiphy_get_supported_freqs(