scan.c

linux内核源码

	struct ieeetypes_ibssparamset *pibss;
	DECLARE_MAC_BUF(mac);
	struct ieeetypes_countryinfoset *pcountryinfo;
	u8 *pos, *end, *p;
	u8 n_ex_rates = 0, got_basic_rates = 0, n_basic_rates = 0;
	u16 beaconsize = 0;
	int ret;

	lbs_deb_enter(LBS_DEB_SCAN);

	if (*bytesleft >= sizeof(beaconsize)) {
		/* Extract & convert beacon size from the command buffer */
		beaconsize = le16_to_cpu(get_unaligned((u16 *)*pbeaconinfo));
		*bytesleft -= sizeof(beaconsize);
		*pbeaconinfo += sizeof(beaconsize);
	}

	if (beaconsize == 0 || beaconsize > *bytesleft) {
		*pbeaconinfo += *bytesleft;
		*bytesleft = 0;
		ret = -1;
		goto done;
	}

	/* Initialize the current working beacon pointer for this BSS iteration */
	pos = *pbeaconinfo;
	end = pos + beaconsize;

	/* Advance the return beacon pointer past the current beacon */
	*pbeaconinfo += beaconsize;
	*bytesleft -= beaconsize;

	memcpy(bss->bssid, pos, ETH_ALEN);
	lbs_deb_scan("process_bss: AP BSSID %s\n", print_mac(mac, bss->bssid));
	pos += ETH_ALEN;

	if ((end - pos) < 12) {
		lbs_deb_scan("process_bss: Not enough bytes left\n");
		ret = -1;
		goto done;
	}

	/*
	 * next 4 fields are RSSI, time stamp, beacon interval,
	 *   and capability information
	 */

	/* RSSI is 1 byte long */
	bss->rssi = *pos;
	lbs_deb_scan("process_bss: RSSI=%02X\n", *pos);
	pos++;

	/* time stamp is 8 bytes long */
	pos += 8;

	/* beacon interval is 2 bytes long */
	bss->beaconperiod = le16_to_cpup((void *) pos);
	pos += 2;

	/* capability information is 2 bytes long */
	bss->capability = le16_to_cpup((void *) pos);
	lbs_deb_scan("process_bss: capabilities = 0x%4X\n", bss->capability);
	pos += 2;

	if (bss->capability & WLAN_CAPABILITY_PRIVACY)
		lbs_deb_scan("process_bss: AP WEP enabled\n");
	if (bss->capability & WLAN_CAPABILITY_IBSS)
		bss->mode = IW_MODE_ADHOC;
	else
		bss->mode = IW_MODE_INFRA;

	/* rest of the current buffer are IE's */
	lbs_deb_scan("process_bss: IE length for this AP = %zd\n", end - pos);
	lbs_deb_hex(LBS_DEB_SCAN, "process_bss: IE info", pos, end - pos);

	/* process variable IE */
	while (pos <= end - 2) {
		struct ieee80211_info_element * elem =
			(struct ieee80211_info_element *) pos;

		if (pos + elem->len > end) {
			lbs_deb_scan("process_bss: error in processing IE, "
			       "bytes left < IE length\n");
			break;
		}

		switch (elem->id) {
		case MFIE_TYPE_SSID:
			bss->ssid_len = elem->len;
			memcpy(bss->ssid, elem->data, elem->len);
			lbs_deb_scan("ssid '%s', ssid length %u\n",
			             escape_essid(bss->ssid, bss->ssid_len),
			             bss->ssid_len);
			break;

		case MFIE_TYPE_RATES:
			n_basic_rates = min_t(u8, MAX_RATES, elem->len);
			memcpy(bss->rates, elem->data, n_basic_rates);
			got_basic_rates = 1;
			break;

		case MFIE_TYPE_FH_SET:
			pFH = (struct ieeetypes_fhparamset *) pos;
			memmove(&bss->phyparamset.fhparamset, pFH,
				sizeof(struct ieeetypes_fhparamset));
#if 0 /* I think we can store these LE */
			bss->phyparamset.fhparamset.dwelltime
			    = le16_to_cpu(bss->phyparamset.fhparamset.dwelltime);
#endif
			break;

		case MFIE_TYPE_DS_SET:
			pDS = (struct ieeetypes_dsparamset *) pos;
			bss->channel = pDS->currentchan;
			memcpy(&bss->phyparamset.dsparamset, pDS,
			       sizeof(struct ieeetypes_dsparamset));
			break;

		case MFIE_TYPE_CF_SET:
			pCF = (struct ieeetypes_cfparamset *) pos;
			memcpy(&bss->ssparamset.cfparamset, pCF,
			       sizeof(struct ieeetypes_cfparamset));
			break;

		case MFIE_TYPE_IBSS_SET:
			pibss = (struct ieeetypes_ibssparamset *) pos;
			bss->atimwindow = le32_to_cpu(pibss->atimwindow);
			memmove(&bss->ssparamset.ibssparamset, pibss,
				sizeof(struct ieeetypes_ibssparamset));
#if 0
			bss->ssparamset.ibssparamset.atimwindow
			    = le16_to_cpu(bss->ssparamset.ibssparamset.atimwindow);
#endif
			break;

		case MFIE_TYPE_COUNTRY:
			pcountryinfo = (struct ieeetypes_countryinfoset *) pos;
			if (pcountryinfo->len < sizeof(pcountryinfo->countrycode)
			    || pcountryinfo->len > 254) {
				lbs_deb_scan("process_bss: 11D- Err "
				       "CountryInfo len =%d min=%zd max=254\n",
				       pcountryinfo->len,
				       sizeof(pcountryinfo->countrycode));
				ret = -1;
				goto done;
			}

			memcpy(&bss->countryinfo,
			       pcountryinfo, pcountryinfo->len + 2);
			lbs_deb_hex(LBS_DEB_SCAN, "process_bss: 11d countryinfo",
				(u8 *) pcountryinfo,
				(u32) (pcountryinfo->len + 2));
			break;

		case MFIE_TYPE_RATES_EX:
			/* only process extended supported rate if data rate is
			 * already found. Data rate IE should come before
			 * extended supported rate IE
			 */
			if (!got_basic_rates)
				break;

			n_ex_rates = elem->len;
			if (n_basic_rates + n_ex_rates > MAX_RATES)
				n_ex_rates = MAX_RATES - n_basic_rates;

			p = bss->rates + n_basic_rates;
			memcpy(p, elem->data, n_ex_rates);
			break;

		case MFIE_TYPE_GENERIC:
			if (elem->len >= 4 &&
			    elem->data[0] == 0x00 &&
			    elem->data[1] == 0x50 &&
			    elem->data[2] == 0xf2 &&
			    elem->data[3] == 0x01) {
				bss->wpa_ie_len = min(elem->len + 2,
				                      MAX_WPA_IE_LEN);
				memcpy(bss->wpa_ie, elem, bss->wpa_ie_len);
				lbs_deb_hex(LBS_DEB_SCAN, "process_bss: WPA IE", bss->wpa_ie,
				            elem->len);
			} else if (elem->len >= MARVELL_MESH_IE_LENGTH &&
			    elem->data[0] == 0x00 &&
			    elem->data[1] == 0x50 &&
			    elem->data[2] == 0x43 &&
			    elem->data[3] == 0x04) {
				bss->mesh = 1;
			}
			break;

		case MFIE_TYPE_RSN:
			bss->rsn_ie_len = min(elem->len + 2, MAX_WPA_IE_LEN);
			memcpy(bss->rsn_ie, elem, bss->rsn_ie_len);
			lbs_deb_hex(LBS_DEB_SCAN, "process_bss: RSN_IE", bss->rsn_ie, elem->len);
			break;

		default:
			break;
		}

		pos += elem->len + 2;
	}

	/* Timestamp */
	bss->last_scanned = jiffies;
	libertas_unset_basic_rate_flags(bss->rates, sizeof(bss->rates));

	ret = 0;

done:
	lbs_deb_leave_args(LBS_DEB_SCAN, "ret %d", ret);
	return ret;
}

/**
 *  @brief This function finds a specific compatible BSSID in the scan list
 *
 *  Used in association code
 *
 *  @param adapter  A pointer to wlan_adapter
 *  @param bssid    BSSID to find in the scan list
 *  @param mode     Network mode: Infrastructure or IBSS
 *
 *  @return         index in BSSID list, or error return code (< 0)
 */
struct bss_descriptor *libertas_find_bssid_in_list(wlan_adapter * adapter,
		u8 * bssid, u8 mode)
{
	struct bss_descriptor * iter_bss;
	struct bss_descriptor * found_bss = NULL;

	lbs_deb_enter(LBS_DEB_SCAN);

	if (!bssid)
		goto out;

	lbs_deb_hex(LBS_DEB_SCAN, "looking for",
		bssid, ETH_ALEN);

	/* Look through the scan table for a compatible match.  The loop will
	 *   continue past a matched bssid that is not compatible in case there
	 *   is an AP with multiple SSIDs assigned to the same BSSID
	 */
	mutex_lock(&adapter->lock);
	list_for_each_entry (iter_bss, &adapter->network_list, list) {
		if (compare_ether_addr(iter_bss->bssid, bssid))
			continue; /* bssid doesn't match */
		switch (mode) {
		case IW_MODE_INFRA:
		case IW_MODE_ADHOC:
			if (!is_network_compatible(adapter, iter_bss, mode))
				break;
			found_bss = iter_bss;
			break;
		default:
			found_bss = iter_bss;
			break;
		}
	}
	mutex_unlock(&adapter->lock);

out:
	lbs_deb_leave_args(LBS_DEB_SCAN, "found_bss %p", found_bss);
	return found_bss;
}

/**
 *  @brief This function finds ssid in ssid list.
 *
 *  Used in association code
 *
 *  @param adapter  A pointer to wlan_adapter
 *  @param ssid     SSID to find in the list
 *  @param bssid    BSSID to qualify the SSID selection (if provided)
 *  @param mode     Network mode: Infrastructure or IBSS
 *
 *  @return         index in BSSID list
 */
struct bss_descriptor * libertas_find_ssid_in_list(wlan_adapter * adapter,
		   u8 *ssid, u8 ssid_len, u8 * bssid, u8 mode,
		   int channel)
{
	u8 bestrssi = 0;
	struct bss_descriptor * iter_bss = NULL;
	struct bss_descriptor * found_bss = NULL;
	struct bss_descriptor * tmp_oldest = NULL;

	lbs_deb_enter(LBS_DEB_SCAN);

	mutex_lock(&adapter->lock);

	list_for_each_entry (iter_bss, &adapter->network_list, list) {
		if (   !tmp_oldest
		    || (iter_bss->last_scanned < tmp_oldest->last_scanned))
			tmp_oldest = iter_bss;

		if (libertas_ssid_cmp(iter_bss->ssid, iter_bss->ssid_len,
		                      ssid, ssid_len) != 0)
			continue; /* ssid doesn't match */
		if (bssid && compare_ether_addr(iter_bss->bssid, bssid) != 0)
			continue; /* bssid doesn't match */
		if ((channel > 0) && (iter_bss->channel != channel))
			continue; /* channel doesn't match */

		switch (mode) {
		case IW_MODE_INFRA:
		case IW_MODE_ADHOC:
			if (!is_network_compatible(adapter, iter_bss, mode))
				break;

			if (bssid) {
				/* Found requested BSSID */
				found_bss = iter_bss;
				goto out;
			}

			if (SCAN_RSSI(iter_bss->rssi) > bestrssi) {
				bestrssi = SCAN_RSSI(iter_bss->rssi);
				found_bss = iter_bss;
			}
			break;
		case IW_MODE_AUTO:
		default:
			if (SCAN_RSSI(iter_bss->rssi) > bestrssi) {
				bestrssi = SCAN_RSSI(iter_bss->rssi);
				found_bss = iter_bss;
			}
			break;
		}
	}

out:
	mutex_unlock(&adapter->lock);
	lbs_deb_leave_args(LBS_DEB_SCAN, "found_bss %p", found_bss);
	return found_bss;
}

/**
 *  @brief This function finds the best SSID in the Scan List
 *
 *  Search the scan table for the best SSID that also matches the current
 *   adapter network preference (infrastructure or adhoc)
 *
 *  @param adapter  A pointer to wlan_adapter
 *
 *  @return         index in BSSID list
 */
static struct bss_descriptor * libertas_find_best_ssid_in_list(wlan_adapter * adapter,
		u8 mode)
{
	u8 bestrssi = 0;
	struct bss_descriptor * iter_bss;
	struct bss_descriptor * best_bss = NULL;

	lbs_deb_enter(LBS_DEB_SCAN);

	mutex_lock(&adapter->lock);

	list_for_each_entry (iter_bss, &adapter->network_list, list) {
		switch (mode) {
		case IW_MODE_INFRA:
		case IW_MODE_ADHOC:
			if (!is_network_compatible(adapter, iter_bss, mode))
				break;
			if (SCAN_RSSI(iter_bss->rssi) <= bestrssi)
				break;
			bestrssi = SCAN_RSSI(iter_bss->rssi);
			best_bss = iter_bss;
			break;
		case IW_MODE_AUTO:
		default:
			if (SCAN_RSSI(iter_bss->rssi) <= bestrssi)
				break;
			bestrssi = SCAN_RSSI(iter_bss->rssi);
			best_bss = iter_bss;
			break;
		}
	}

	mutex_unlock(&adapter->lock);
	lbs_deb_leave_args(LBS_DEB_SCAN, "best_bss %p", best_bss);
	return best_bss;
}

/**
 *  @brief Find the AP with specific ssid in the scan list
 *
 *  Used from association worker.
 *
 *  @param priv         A pointer to wlan_private structure
 *  @param pSSID        A pointer to AP's ssid
 *
 *  @return             0--success, otherwise--fail
 */
int libertas_find_best_network_ssid(wlan_private * priv,
		u8 *out_ssid, u8 *out_ssid_len, u8 preferred_mode, u8 *out_mode)
{
	wlan_adapter *adapter = priv->adapter;
	int ret = -1;
	struct bss_descriptor * found;

	lbs_deb_enter(LBS_DEB_SCAN);

	wlan_scan_networks(priv, NULL, 1);
	if (adapter->surpriseremoved)
		goto out;

	wait_event_interruptible(adapter->cmd_pending, !adapter->nr_cmd_pending);

	found = libertas_find_best_ssid_in_list(adapter, preferred_mode);
	if (found && (found->ssid_len > 0)) {
		memcpy(out_ssid, &found->ssid, IW_ESSID_MAX_SIZE);
		*out_ssid_len = found->ssid_len;
		*out_mode = found->mode;
		ret = 0;
	}

out:
	lbs_deb_leave_args(LBS_DEB_SCAN, "ret %d", ret);
	return ret;
}

/**
 *  @brief Scan Network
 *
 *  @param dev          A pointer to net_device structure
 *  @param info         A pointer to iw_request_info structure
 *  @param vwrq         A pointer to iw_param structure
 *  @param extra        A pointer to extra data buf
 *
 *  @return             0 --success, otherwise fail
 */
int libertas_set_scan(struct net_device *dev, struct iw_request_info *info,
		  struct iw_param *vwrq, char *extra)
{
	wlan_private *priv = dev->priv;
	wlan_adapter *adapter = priv->adapter;

	lbs_deb_enter(LBS_DEB_SCAN);

	if (!delayed_work_pending(&priv->scan_work)) {
		queue_delayed_work(priv->work_thread, &priv->scan_work,
		                   msecs_to_jiffies(50));
	}

	if (adapter->surpriseremoved)
		return -1;

	lbs_deb_leave(LBS_DEB_SCAN);
	return 0;
}


/**
 *  @brief Send a scan command for all available channels filtered on a spec
 *
 *  Used in association code and from debugfs
 *
 *  @param priv             A pointer to wlan_private structure
 *  @param ssid             A pointer to the SSID to scan for
 *  @param ssid_len         Length of the SSID
 *  @param clear_ssid       Should existing scan results with this SSID
 *                          be cleared?
 *  @param prequestedssid   A pointer to AP's ssid
 *  @param keeppreviousscan Flag used to save/clear scan table before scan
 *
 *  @return                0-success, otherwise fail
 */