P2P: Provide mechanism for figuring out p2p_scan_ie() buffer need

The new function, p2p_scan_ie_buf_len(), can be used to figure out
how large a buffer needs to be allocated for p2p_scan_ie() use. This
makes it easier to add new data into the buffer without forcing all
callers to be updated to use a larger buffer.

src/drivers/driver_test.c

@@ -2983,6 +2983,7 @@ static int test_p2p_scan(void *ctx, enum p2p_scan_type type, int freq,
 	int ret;
 	struct wpabuf *wps_ie, *ies;
 	int social_channels[] = { 2412, 2437, 2462, 0, 0 };
+	size_t ielen;
 
 	wpa_printf(MSG_DEBUG, "%s(type=%d freq=%d)",
 		   __func__, type, freq);
@@ -3004,7 +3005,8 @@ static int test_p2p_scan(void *ctx, enum p2p_scan_type type, int freq,
 	if (wps_ie == NULL)
 		return -1;
 
-	ies = wpabuf_alloc(wpabuf_len(wps_ie) + 100);
+	ielen = p2p_scan_ie_buf_len(drv->p2p);
+	ies = wpabuf_alloc(wpabuf_len(wps_ie) + ielen);
 	if (ies == NULL) {
 		wpabuf_free(wps_ie);
 		return -1;

src/p2p/p2p.c

@@ -2462,6 +2462,12 @@ void p2p_scan_ie(struct p2p_data *p2p, struct wpabuf *ies)
 }
 
 
+size_t p2p_scan_ie_buf_len(struct p2p_data *p2p)
+{
+	return 100;
+}
+
+
 int p2p_ie_text(struct wpabuf *p2p_ie, char *buf, char *end)
 {
 	return p2p_attr_text(p2p_ie, buf, end);

src/p2p/p2p.h

@@ -1343,6 +1343,13 @@ int p2p_assoc_req_ie(struct p2p_data *p2p, const u8 *bssid, u8 *buf,
  */
 void p2p_scan_ie(struct p2p_data *p2p, struct wpabuf *ies);
 
+/**
+ * p2p_scan_ie_buf_len - Get maximum buffer length needed for p2p_scan_ie
+ * @p2p: P2P module context from p2p_init()
+ * Returns: Number of octets that p2p_scan_ie() may add to the buffer
+ */
+size_t p2p_scan_ie_buf_len(struct p2p_data *p2p);
+
 /**
  * p2p_go_params - Generate random P2P group parameters
  * @p2p: P2P module context from p2p_init()

wpa_supplicant/p2p_supplicant.c

@@ -92,6 +92,7 @@ static int wpas_p2p_scan(void *ctx, enum p2p_scan_type type, int freq,
 	int ret;
 	struct wpabuf *wps_ie, *ies;
 	int social_channels[] = { 2412, 2437, 2462, 0, 0 };
+	size_t ielen;
 
 	if (wpa_s->global->p2p_disabled || wpa_s->global->p2p == NULL)
 		return -1;
@@ -110,7 +111,8 @@ static int wpas_p2p_scan(void *ctx, enum p2p_scan_type type, int freq,
 	if (wps_ie == NULL)
 		return -1;
 
-	ies = wpabuf_alloc(wpabuf_len(wps_ie) + 100);
+	ielen = p2p_scan_ie_buf_len(wpa_s->global->p2p);
+	ies = wpabuf_alloc(wpabuf_len(wps_ie) + ielen);
 	if (ies == NULL) {
 		wpabuf_free(wps_ie);
 		return -1;
@@ -2766,6 +2768,7 @@ static void wpas_p2p_join_scan(void *eloop_ctx, void *timeout_ctx)
 	int ret;
 	struct wpa_driver_scan_params params;
 	struct wpabuf *wps_ie, *ies;
+	size_t ielen;
 
 	os_memset(&params, 0, sizeof(params));
 
@@ -2782,7 +2785,8 @@ static void wpas_p2p_join_scan(void *eloop_ctx, void *timeout_ctx)
 		return;
 	}
 
-	ies = wpabuf_alloc(wpabuf_len(wps_ie) + 100);
+	ielen = p2p_scan_ie_buf_len(wpa_s->global->p2p);
+	ies = wpabuf_alloc(wpabuf_len(wps_ie) + ielen);
 	if (ies == NULL) {
 		wpabuf_free(wps_ie);
 		wpas_p2p_scan_res_join(wpa_s, NULL);

wpa_supplicant/scan.c

@@ -471,7 +471,8 @@ static void wpa_supplicant_scan(void *eloop_ctx, void *timeout_ctx)
 
 #ifdef CONFIG_P2P
 	if (wps_ie) {
-		if (wpabuf_resize(&wps_ie, 100) == 0) {
+		size_t ielen = p2p_scan_ie_buf_len(wpa_s->global->p2p);
+		if (wpabuf_resize(&wps_ie, ielen) == 0) {
 			wpas_p2p_scan_ie(wpa_s, wps_ie);
 			params.extra_ies = wpabuf_head(wps_ie);
 			params.extra_ies_len = wpabuf_len(wps_ie);