From: "Luis R. Rodriguez" <lrodriguez@atheros.com>
To: johannes@sipsolutions.net
Cc: linux-wireless@vger.kernel.org, 8an@praha12.net,
	"Luis R. Rodriguez" <lrodriguez@atheros.com>
Subject: [PATCH] iw: add country IE parsing
Date: Wed, 17 Feb 2010 21:13:28 -0500
Message-Id: <1266459208-12408-1-git-send-email-lrodriguez@atheros.com>
Sender: linux-wireless-owner@vger.kernel.org

Spits out the channels as seen on the IE, useful when debugging
issues with APs. When found the equivalent distance of the
coverage class is printed out in meters.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
---

Sorry, resending, I mistakenly sent to lkml instead of linux-wireless.

OK so I removed the line that says we're printing IEs and also
added a distance compuation based on Lukáš Turek's forumal.

coverage = (distance + 449) / 450;
coverage/450 = distance + 499
(coverage/450) - 499 = distance 

So in meters:

distance = (coverage/450) - 499

 scan.c |   96 ++++++++++++++++++++++++++++++++++++++++++++++++++++-----------
 1 files changed, 79 insertions(+), 17 deletions(-)

diff --git a/scan.c b/scan.c
index ec63e61..2d7f15e 100644
--- a/scan.c
+++ b/scan.c
@@ -36,6 +36,23 @@ struct scan_params {
 	bool show_both_ie_sets;
 };
 
+#define IEEE80211_COUNTRY_EXTENSION_ID 201
+
+struct ieee80211_country_ie_triplet {
+	union {
+		struct {
+			__u8 first_channel;
+			__u8 num_channels;
+			__s8 max_power;
+		} __attribute__ ((packed)) chans;
+		struct {
+			__u8 reg_extension_id;
+			__u8 reg_class;
+			__u8 coverage_class;
+		} __attribute__ ((packed)) ext;
+	};
+} __attribute__ ((packed));
+
 static int handle_scan(struct nl80211_state *state,
 		       struct nl_cb *cb,
 		       struct nl_msg *msg,
@@ -143,29 +160,74 @@ static void print_ds(const uint8_t type, uint8_t len, const uint8_t *data)
 	printf(" channel %d\n", data[0]);
 }
 
-static void print_country(const uint8_t type, uint8_t len, const uint8_t *data)
+static const char *country_env_str(char environment)
 {
-	int i;
-
-	printf(" %.*s", 2, data);
-	switch (data[2]) {
+	switch (environment) {
 	case 'I':
-		printf(" (indoor)");
-		break;
+		return "Indoor only";
 	case 'O':
-		printf(" (outdoor)");
-		break;
+		return "Outdoor only";
 	case ' ':
-		printf(" (in/outdoor)");
-		break;
+		return "Indoor/Outdoor";
 	default:
-		printf(" (invalid environment)");
-		break;
+		return "bogus";
 	}
-	printf(", data:");
-	for(i=0; i<len-3; i++)
-		printf(" %.02x", data[i + 3]);
-	printf("\n");
+}
+
+/*
+ * Using the inverse of the distance to coverage class
+ * formula we get that in meters
+ * distance = (coverage/450) - 499
+ */
+static int coverage_class_to_distance(__u8 coverage_class)
+{
+	return (coverage_class / 450) - 499;
+}
+
+static void print_country(const uint8_t type, uint8_t len, const uint8_t *data)
+{
+	printf(" %.*s", 2, data);
+
+	printf("\tEnvironment: %s\n", country_env_str(data[2]));
+
+	data += 3;
+	len -= 3;
+
+	if (len < 3) {
+		printf("\t\tNo country IE triplets present\n");
+		return;
+	}
+
+	while (len >= 3) {
+		int end_channel;
+		struct ieee80211_country_ie_triplet *triplet =
+			(struct ieee80211_country_ie_triplet *) data;
+
+		if (triplet->ext.reg_extension_id >= IEEE80211_COUNTRY_EXTENSION_ID) {
+			printf("\t\tExtension ID: %d Regulatory Class: %d Coverage class: %d (Approx %d meters)\n",
+			       triplet->ext.reg_extension_id,
+			       triplet->ext.reg_class,
+			       triplet->ext.coverage_class,
+			       coverage_class_to_distance(triplet->ext.coverage_class));
+
+			data += 3;
+			len -= 3;
+			continue;
+		}
+
+		/* 2 GHz */
+		if (triplet->chans.first_channel <= 14)
+			end_channel = triplet->chans.first_channel + (triplet->chans.num_channels - 1);
+		else
+			end_channel =  triplet->chans.first_channel + (4 * (triplet->chans.num_channels - 1));
+
+		printf("\t\tChannels [%d - %d]\n", triplet->chans.first_channel, end_channel);
+
+		data += 3;
+		len -= 3;
+	}
+
+	return;
 }
 
 static void print_powerconstraint(const uint8_t type, uint8_t len, const uint8_t *data)
-- 
1.6.3.3