From 85a6fc25f11533d88feae3e22780227a346c90a7 Mon Sep 17 00:00:00 2001
From: Denis Kenzior <denkenz@gmail.com>
Date: Sat, 18 Sep 2021 14:19:41 -0500
Subject: [PATCH] nl80211util: Add chandef parser

Parse chandef elements from NL80211_CMD_GET_INTERFACE.  This provides
information on the current operating channel.
---
 src/band.h        | 16 ++++++++++++++++
 src/nl80211util.c | 30 ++++++++++++++++++++++++++++++
 src/nl80211util.h |  4 ++++
 3 files changed, 50 insertions(+)

diff --git a/src/band.h b/src/band.h
index 4958a63a..dfb348eb 100644
--- a/src/band.h
+++ b/src/band.h
@@ -27,6 +27,22 @@ enum ofdm_channel_width {
 	OFDM_CHANNEL_WIDTH_160MHZ,
 };
 
+enum band_chandef_width {
+	BAND_CHANDEF_WIDTH_20NOHT = 0,
+	BAND_CHANDEF_WIDTH_20,
+	BAND_CHANDEF_WIDTH_40,
+	BAND_CHANDEF_WIDTH_80,
+	BAND_CHANDEF_WIDTH_80P80,
+	BAND_CHANDEF_WIDTH_160,
+};
+
+struct band_chandef {
+	uint32_t frequency;
+	uint32_t channel_width;
+	uint32_t center1_frequency;
+	uint32_t center2_frequency;
+};
+
 struct band {
 	uint8_t vht_mcs_set[8];
 	uint8_t vht_capabilities[4];
diff --git a/src/nl80211util.c b/src/nl80211util.c
index 7a752a66..d9d4819d 100644
--- a/src/nl80211util.c
+++ b/src/nl80211util.c
@@ -31,6 +31,7 @@
 #include "linux/nl80211.h"
 
 #include "src/nl80211util.h"
+#include "src/band.h"
 
 typedef bool (*attr_handler)(const void *data, uint16_t len, void *o);
 
@@ -138,6 +139,11 @@ static attr_handler handler_for_type(enum nl80211_attrs type)
 	case NL80211_ATTR_ACK:
 		return extract_flag;
 	case NL80211_ATTR_WIPHY_FREQ:
+	case NL80211_ATTR_WIPHY_FREQ_OFFSET:
+	case NL80211_ATTR_WIPHY_CHANNEL_TYPE:
+	case NL80211_ATTR_CHANNEL_WIDTH:
+	case NL80211_ATTR_CENTER_FREQ1:
+	case NL80211_ATTR_CENTER_FREQ2:
 		return extract_uint32;
 	default:
 		break;
@@ -430,3 +436,27 @@ struct l_genl_msg *nl80211_build_cmd_frame(uint32_t ifindex,
 
 	return msg;
 }
+
+int nl80211_parse_chandef(struct l_genl_msg *msg, struct band_chandef *out)
+{
+	struct band_chandef t;
+
+	if (nl80211_parse_attrs(msg,
+			NL80211_ATTR_WIPHY_FREQ, &t.frequency,
+			NL80211_ATTR_CHANNEL_WIDTH, &t.channel_width,
+			NL80211_ATTR_CENTER_FREQ1, &t.center1_frequency,
+			NL80211_ATTR_UNSPEC) < 0)
+		return -ENOENT;
+
+	t.center2_frequency = 0;
+
+	/* Try to parse CENTER_FREQ2, but it is given only for 80P80 */
+	if (t.channel_width == NL80211_CHAN_WIDTH_80P80 &&
+			nl80211_parse_attrs(msg,
+				NL80211_ATTR_CENTER_FREQ2, &t.center2_frequency,
+				NL80211_ATTR_UNSPEC) < 0)
+		return -ENOENT;
+
+	memcpy(out, &t, sizeof(t));
+	return 0;
+}
diff --git a/src/nl80211util.h b/src/nl80211util.h
index 70de0897..01777195 100644
--- a/src/nl80211util.h
+++ b/src/nl80211util.h
@@ -22,6 +22,8 @@
 
 #include <ell/ell.h>
 
+struct band_chandef;
+
 int nl80211_parse_attrs(struct l_genl_msg *msg, int tag, ...);
 
 struct l_genl_msg *nl80211_build_new_key_group(uint32_t ifindex,
@@ -51,3 +53,5 @@ struct l_genl_msg *nl80211_build_cmd_frame(uint32_t ifindex,
 						uint32_t freq,
 						struct iovec *iov,
 						size_t iov_len);
+
+int nl80211_parse_chandef(struct l_genl_msg *msg, struct band_chandef *out);