Support set position API in wmediumd

With set position API in wmediumd, we can connect/disconnect wifi
connection with distance between stations like real world.

Type command "wmediumd_control set_position" to use it.

Bug: 230432123
Test: Creating several cuttlefish instance with "launch_cvd", and
change X/Y position of station with "wmediumd_control set_position".
Then the result could be seen with "wmediumd_control list_stations" and
the cuttlefish screen.

Change-Id: I3858b7af8fdd1172b3a544312fa17cc7583ed042

5 files changed, 60 insertions, 13 deletions

diff --git a/wmediumd/api.h b/wmediumd/api.h
index ba507e4..8fa8fe0 100644
--- a/wmediumd/api.h
+++ b/wmediumd/api.h
@@ -70,6 +70,11 @@ enum wmediumd_message {
 	WMEDIUMD_MSG_STOP_PCAP,
 
 	WMEDIUMD_MSG_STATIONS_LIST,
+
+	/*
+	 * Set position of station.
+	 */
+	WMEDIUMD_MSG_SET_POSITION,
 };
 
 struct wmediumd_message_header {
@@ -109,7 +114,7 @@ struct wmediumd_tx_start {
 };
 
 #pragma pack(push, 1)
-	struct wmediumd_set_snr {
+struct wmediumd_set_snr {
 	/* MAC address of node 1 */
 	uint8_t node1_mac[6];
 	/* MAC address of node 2 */
@@ -143,6 +148,15 @@ struct wmediumd_station_infos {
 	uint32_t count;
 	struct wmediumd_station_info stations[0];
 };
+
+struct wmediumd_set_position {
+	/* MAC address */
+	uint8_t mac[6];
+	/* X position of station */
+	double x;
+	/* Y position of station */
+	double y;
+};
 #pragma pack(pop)
 
 #endif /* _WMEDIUMD_API_H */
diff --git a/wmediumd/config.c b/wmediumd/config.c
index fc4986a..0500949 100644
--- a/wmediumd/config.c
+++ b/wmediumd/config.c
@@ -32,6 +32,14 @@
 #include "wmediumd.h"
 #include "config.h"
 
+#ifndef MIN
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+#endif
+
+#ifndef MAX
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+#endif
+
 static void string_to_mac_address(const char *str, u8 *addr)
 {
 	int a[ETH_ALEN];
@@ -110,7 +118,7 @@ static int calc_path_loss_free_space(void *model_param,
 	 * https://en.wikipedia.org/wiki/Free-space_path_loss
 	 */
 	PL = 20.0 * log10(4.0 * M_PI * d * FREQ_1CH / SPEED_LIGHT);
-	return PL;
+	return MAX(PL, 0);
 }
 /*
  * Calculate path loss based on a log distance model
@@ -146,7 +154,7 @@ static int calc_path_loss_log_distance(void *model_param,
 	 */
 	PL = PL0 + 10.0 * param->path_loss_exponent * log10(d) + param->Xg;
 
-	return PL;
+	return MAX(PL, 0);
 }
 /*
  * Calculate path loss based on a itu model
@@ -176,23 +184,23 @@ static int calc_path_loss_itu(void *model_param,
 	 * nFLOORS: number of floors
 	 */
 	PL = 20.0 * log10(FREQ_1CH) + N * log10(d) + param->LF * param->nFLOORS - 28;
-	return PL;
+	return MAX(PL, 0);
 }
 
 static void recalc_path_loss(struct wmediumd *ctx)
 {
-	int start, end, path_loss;
-
+	int start, end, tx_power, path_loss, signal;
 	for (start = 0; start < ctx->num_stas; start++) {
 		for (end = 0; end < ctx->num_stas; end++) {
-			if (start == end)
+			if (start == end) {
 				continue;
+			}
 
-			path_loss = ctx->calc_path_loss(ctx->path_loss_param,
-				ctx->sta_array[end], ctx->sta_array[start]);
-			ctx->snr_matrix[ctx->num_stas * start + end] =
-				ctx->sta_array[start]->tx_power - path_loss -
-				NOISE_LEVEL;
+			tx_power = ctx->sta_array[start]->tx_power;
+			path_loss = ctx->calc_path_loss(ctx->path_loss_param, ctx->sta_array[end], ctx->sta_array[start]);
+			// Test breakage exists in WifiStatsTests when signal is not negative value.
+			signal = MIN(tx_power - path_loss, -1);
+			ctx->snr_matrix[ctx->num_stas * start + end] = signal - NOISE_LEVEL;
 		}
 	}
 }
@@ -700,3 +708,7 @@ int clear_config(struct wmediumd *ctx) {
 
 	return 0;
 }
+
+void calc_path_loss(struct wmediumd *ctx) {
+	recalc_path_loss(ctx);
+}
\ No newline at end of file
diff --git a/wmediumd/config.h b/wmediumd/config.h
index 471ffe1..feac4c2 100644
--- a/wmediumd/config.h
+++ b/wmediumd/config.h
@@ -24,6 +24,7 @@
 #ifndef CONFIG_H_
 #define CONFIG_H_
 
+void calc_path_loss(struct wmediumd *ctx);
 int clear_config(struct wmediumd *ctx);
 int validate_config(const char* file);
 int load_config(struct wmediumd *ctx, const char *file, const char *per_file);
diff --git a/wmediumd/wmediumd.c b/wmediumd/wmediumd.c
index 860c214..31f2ce3 100644
--- a/wmediumd/wmediumd.c
+++ b/wmediumd/wmediumd.c
@@ -1148,6 +1148,21 @@ static int process_get_stations_message(struct wmediumd *ctx, ssize_t *response_
 	return 0;
 }
 
+static int process_set_position_message(struct wmediumd *ctx, struct wmediumd_set_position *set_position) {
+	struct station *node = get_station_by_addr(ctx, set_position->mac);
+
+	if (node == NULL) {
+		return -1;
+	}
+
+	node->x = set_position->x;
+	node->y = set_position->y;
+
+	calc_path_loss(ctx);
+
+	return 0;
+}
+
 static const struct usfstl_vhost_user_ops wmediumd_vu_ops = {
 	.connected = wmediumd_vu_connected,
 	.handle = wmediumd_vu_handle,
@@ -1268,6 +1283,11 @@ static void wmediumd_api_handler(struct usfstl_loop_entry *entry)
 	case WMEDIUMD_MSG_STOP_PCAP:
 		close_pcapng(ctx);
 		break;
+	case WMEDIUMD_MSG_SET_POSITION:
+		if (process_set_position_message(ctx, (struct wmediumd_set_position *)data) < 0) {
+			response = WMEDIUMD_MSG_INVALID;
+		}
+		break;
 	case WMEDIUMD_MSG_ACK:
 		assert(client->wait_for_ack == true);
 		assert(hdr.data_len == 0);
diff --git a/wmediumd/wmediumd.h b/wmediumd/wmediumd.h
index 4001998..f8bc395 100644
--- a/wmediumd/wmediumd.h
+++ b/wmediumd/wmediumd.h
@@ -110,7 +110,7 @@ enum {
 
 #define VERSION_NR 1
 
-#define SNR_DEFAULT 90
+#define SNR_DEFAULT 30
 
 #include <stdint.h>
 #include <stdbool.h>