1 files changed, 1016 insertions, 0 deletions

diff --git a/net/mac80211/mesh_hwmp.c b/net/mac80211/mesh_hwmp.c
new file mode 100644
index 00000000..2b180530
--- /dev/null
+++ b/net/mac80211/mesh_hwmp.c
@@ -0,0 +1,1016 @@
+/*
+ * Copyright (c) 2008, 2009 open80211s Ltd.
+ * Author:     Luis Carlos Cobo <luisca@cozybit.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/slab.h>
+#include "mesh.h"
+
+#ifdef CONFIG_MAC80211_VERBOSE_MHWMP_DEBUG
+#define mhwmp_dbg(fmt, args...)   printk(KERN_DEBUG "Mesh HWMP: " fmt, ##args)
+#else
+#define mhwmp_dbg(fmt, args...)   do { (void)(0); } while (0)
+#endif
+
+#define TEST_FRAME_LEN	8192
+#define MAX_METRIC	0xffffffff
+#define ARITH_SHIFT	8
+
+/* Number of frames buffered per destination for unresolved destinations */
+#define MESH_FRAME_QUEUE_LEN	10
+#define MAX_PREQ_QUEUE_LEN	64
+
+/* Destination only */
+#define MP_F_DO	0x1
+/* Reply and forward */
+#define MP_F_RF	0x2
+/* Unknown Sequence Number */
+#define MP_F_USN    0x01
+/* Reason code Present */
+#define MP_F_RCODE  0x02
+
+static void mesh_queue_preq(struct mesh_path *, u8);
+
+static inline u32 u32_field_get(u8 *preq_elem, int offset, bool ae)
+{
+	if (ae)
+		offset += 6;
+	return get_unaligned_le32(preq_elem + offset);
+}
+
+static inline u32 u16_field_get(u8 *preq_elem, int offset, bool ae)
+{
+	if (ae)
+		offset += 6;
+	return get_unaligned_le16(preq_elem + offset);
+}
+
+/* HWMP IE processing macros */
+#define AE_F			(1<<6)
+#define AE_F_SET(x)		(*x & AE_F)
+#define PREQ_IE_FLAGS(x)	(*(x))
+#define PREQ_IE_HOPCOUNT(x)	(*(x + 1))
+#define PREQ_IE_TTL(x)		(*(x + 2))
+#define PREQ_IE_PREQ_ID(x)	u32_field_get(x, 3, 0)
+#define PREQ_IE_ORIG_ADDR(x)	(x + 7)
+#define PREQ_IE_ORIG_SN(x)	u32_field_get(x, 13, 0);
+#define PREQ_IE_LIFETIME(x)	u32_field_get(x, 17, AE_F_SET(x));
+#define PREQ_IE_METRIC(x) 	u32_field_get(x, 21, AE_F_SET(x));
+#define PREQ_IE_TARGET_F(x)	(*(AE_F_SET(x) ? x + 32 : x + 26))
+#define PREQ_IE_TARGET_ADDR(x) 	(AE_F_SET(x) ? x + 33 : x + 27)
+#define PREQ_IE_TARGET_SN(x) 	u32_field_get(x, 33, AE_F_SET(x));
+
+
+#define PREP_IE_FLAGS(x)	PREQ_IE_FLAGS(x)
+#define PREP_IE_HOPCOUNT(x)	PREQ_IE_HOPCOUNT(x)
+#define PREP_IE_TTL(x)		PREQ_IE_TTL(x)
+#define PREP_IE_ORIG_ADDR(x)	(x + 3)
+#define PREP_IE_ORIG_SN(x)	u32_field_get(x, 9, 0);
+#define PREP_IE_LIFETIME(x)	u32_field_get(x, 13, AE_F_SET(x));
+#define PREP_IE_METRIC(x)	u32_field_get(x, 17, AE_F_SET(x));
+#define PREP_IE_TARGET_ADDR(x)	(AE_F_SET(x) ? x + 27 : x + 21)
+#define PREP_IE_TARGET_SN(x)	u32_field_get(x, 27, AE_F_SET(x));
+
+#define PERR_IE_TTL(x)		(*(x))
+#define PERR_IE_TARGET_FLAGS(x)	(*(x + 2))
+#define PERR_IE_TARGET_ADDR(x)	(x + 3)
+#define PERR_IE_TARGET_SN(x)	u32_field_get(x, 9, 0);
+#define PERR_IE_TARGET_RCODE(x)	u16_field_get(x, 13, 0);
+
+#define MSEC_TO_TU(x) (x*1000/1024)
+#define SN_GT(x, y) ((long) (y) - (long) (x) < 0)
+#define SN_LT(x, y) ((long) (x) - (long) (y) < 0)
+
+#define net_traversal_jiffies(s) \
+	msecs_to_jiffies(s->u.mesh.mshcfg.dot11MeshHWMPnetDiameterTraversalTime)
+#define default_lifetime(s) \
+	MSEC_TO_TU(s->u.mesh.mshcfg.dot11MeshHWMPactivePathTimeout)
+#define min_preq_int_jiff(s) \
+	(msecs_to_jiffies(s->u.mesh.mshcfg.dot11MeshHWMPpreqMinInterval))
+#define max_preq_retries(s) (s->u.mesh.mshcfg.dot11MeshHWMPmaxPREQretries)
+#define disc_timeout_jiff(s) \
+	msecs_to_jiffies(sdata->u.mesh.mshcfg.min_discovery_timeout)
+
+enum mpath_frame_type {
+	MPATH_PREQ = 0,
+	MPATH_PREP,
+	MPATH_PERR,
+	MPATH_RANN
+};
+
+static const u8 broadcast_addr[ETH_ALEN] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
+
+static int mesh_path_sel_frame_tx(enum mpath_frame_type action, u8 flags,
+		u8 *orig_addr, __le32 orig_sn, u8 target_flags, u8 *target,
+		__le32 target_sn, const u8 *da, u8 hop_count, u8 ttl,
+		__le32 lifetime, __le32 metric, __le32 preq_id,
+		struct ieee80211_sub_if_data *sdata)
+{
+	struct ieee80211_local *local = sdata->local;
+	struct sk_buff *skb = dev_alloc_skb(local->hw.extra_tx_headroom + 400);
+	struct ieee80211_mgmt *mgmt;
+	u8 *pos;
+	int ie_len;
+
+	if (!skb)
+		return -1;
+	skb_reserve(skb, local->hw.extra_tx_headroom);
+	/* 25 is the size of the common mgmt part (24) plus the size of the
+	 * common action part (1)
+	 */
+	mgmt = (struct ieee80211_mgmt *)
+		skb_put(skb, 25 + sizeof(mgmt->u.action.u.mesh_action));
+	memset(mgmt, 0, 25 + sizeof(mgmt->u.action.u.mesh_action));
+	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
+					  IEEE80211_STYPE_ACTION);
+
+	memcpy(mgmt->da, da, ETH_ALEN);
+	memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
+	/* BSSID == SA */
+	memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
+	mgmt->u.action.category = WLAN_CATEGORY_MESH_PATH_SEL;
+	mgmt->u.action.u.mesh_action.action_code = MESH_PATH_SEL_ACTION;
+
+	switch (action) {
+	case MPATH_PREQ:
+		mhwmp_dbg("sending PREQ to %pM\n", target);
+		ie_len = 37;
+		pos = skb_put(skb, 2 + ie_len);
+		*pos++ = WLAN_EID_PREQ;
+		break;
+	case MPATH_PREP:
+		mhwmp_dbg("sending PREP to %pM\n", target);
+		ie_len = 31;
+		pos = skb_put(skb, 2 + ie_len);
+		*pos++ = WLAN_EID_PREP;
+		break;
+	case MPATH_RANN:
+		mhwmp_dbg("sending RANN from %pM\n", orig_addr);
+		ie_len = sizeof(struct ieee80211_rann_ie);
+		pos = skb_put(skb, 2 + ie_len);
+		*pos++ = WLAN_EID_RANN;
+		break;
+	default:
+		kfree_skb(skb);
+		return -ENOTSUPP;
+		break;
+	}
+	*pos++ = ie_len;
+	*pos++ = flags;
+	*pos++ = hop_count;
+	*pos++ = ttl;
+	if (action == MPATH_PREQ) {
+		memcpy(pos, &preq_id, 4);
+		pos += 4;
+	}
+	memcpy(pos, orig_addr, ETH_ALEN);
+	pos += ETH_ALEN;
+	memcpy(pos, &orig_sn, 4);
+	pos += 4;
+	if (action != MPATH_RANN) {
+		memcpy(pos, &lifetime, 4);
+		pos += 4;
+	}
+	memcpy(pos, &metric, 4);
+	pos += 4;
+	if (action == MPATH_PREQ) {
+		/* destination count */
+		*pos++ = 1;
+		*pos++ = target_flags;
+	}
+	if (action != MPATH_RANN) {
+		memcpy(pos, target, ETH_ALEN);
+		pos += ETH_ALEN;
+		memcpy(pos, &target_sn, 4);
+	}
+
+	ieee80211_tx_skb(sdata, skb);
+	return 0;
+}
+
+/**
+ * mesh_send_path error - Sends a PERR mesh management frame
+ *
+ * @target: broken destination
+ * @target_sn: SN of the broken destination
+ * @target_rcode: reason code for this PERR
+ * @ra: node this frame is addressed to
+ */
+int mesh_path_error_tx(u8 ttl, u8 *target, __le32 target_sn,
+		       __le16 target_rcode, const u8 *ra,
+		       struct ieee80211_sub_if_data *sdata)
+{
+	struct ieee80211_local *local = sdata->local;
+	struct sk_buff *skb = dev_alloc_skb(local->hw.extra_tx_headroom + 400);
+	struct ieee80211_mgmt *mgmt;
+	u8 *pos;
+	int ie_len;
+
+	if (!skb)
+		return -1;
+	skb_reserve(skb, local->hw.extra_tx_headroom);
+	/* 25 is the size of the common mgmt part (24) plus the size of the
+	 * common action part (1)
+	 */
+	mgmt = (struct ieee80211_mgmt *)
+		skb_put(skb, 25 + sizeof(mgmt->u.action.u.mesh_action));
+	memset(mgmt, 0, 25 + sizeof(mgmt->u.action.u.mesh_action));
+	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
+					  IEEE80211_STYPE_ACTION);
+
+	memcpy(mgmt->da, ra, ETH_ALEN);
+	memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
+	/* BSSID is left zeroed, wildcard value */
+	mgmt->u.action.category = WLAN_CATEGORY_MESH_PATH_SEL;
+	mgmt->u.action.u.mesh_action.action_code = MESH_PATH_SEL_ACTION;
+	ie_len = 15;
+	pos = skb_put(skb, 2 + ie_len);
+	*pos++ = WLAN_EID_PERR;
+	*pos++ = ie_len;
+	/* ttl */
+	*pos++ = ttl;
+	/* number of destinations */
+	*pos++ = 1;
+	/*
+	 * flags bit, bit 1 is unset if we know the sequence number and
+	 * bit 2 is set if we have a reason code
+	 */
+	*pos = 0;
+	if (!target_sn)
+		*pos |= MP_F_USN;
+	if (target_rcode)
+		*pos |= MP_F_RCODE;
+	pos++;
+	memcpy(pos, target, ETH_ALEN);
+	pos += ETH_ALEN;
+	memcpy(pos, &target_sn, 4);
+	pos += 4;
+	memcpy(pos, &target_rcode, 2);
+
+	ieee80211_tx_skb(sdata, skb);
+	return 0;
+}
+
+void ieee80211s_update_metric(struct ieee80211_local *local,
+		struct sta_info *stainfo, struct sk_buff *skb)
+{
+	struct ieee80211_tx_info *txinfo = IEEE80211_SKB_CB(skb);
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+	int failed;
+
+	if (!ieee80211_is_data(hdr->frame_control))
+		return;
+
+	failed = !(txinfo->flags & IEEE80211_TX_STAT_ACK);
+
+	/* moving average, scaled to 100 */
+	stainfo->fail_avg = ((80 * stainfo->fail_avg + 5) / 100 + 20 * failed);
+	if (stainfo->fail_avg > 95)
+		mesh_plink_broken(stainfo);
+}
+
+static u32 airtime_link_metric_get(struct ieee80211_local *local,
+				   struct sta_info *sta)
+{
+	struct ieee80211_supported_band *sband;
+	/* This should be adjusted for each device */
+	int device_constant = 1 << ARITH_SHIFT;
+	int test_frame_len = TEST_FRAME_LEN << ARITH_SHIFT;
+	int s_unit = 1 << ARITH_SHIFT;
+	int rate, err;
+	u32 tx_time, estimated_retx;
+	u64 result;
+
+	sband = local->hw.wiphy->bands[local->hw.conf.channel->band];
+
+	if (sta->fail_avg >= 100)
+		return MAX_METRIC;
+
+	if (sta->last_tx_rate.flags & IEEE80211_TX_RC_MCS)
+		return MAX_METRIC;
+
+	err = (sta->fail_avg << ARITH_SHIFT) / 100;
+
+	/* bitrate is in units of 100 Kbps, while we need rate in units of
+	 * 1Mbps. This will be corrected on tx_time computation.
+	 */
+	rate = sband->bitrates[sta->last_tx_rate.idx].bitrate;
+	tx_time = (device_constant + 10 * test_frame_len / rate);
+	estimated_retx = ((1 << (2 * ARITH_SHIFT)) / (s_unit - err));
+	result = (tx_time * estimated_retx) >> (2 * ARITH_SHIFT) ;
+	return (u32)result;
+}
+
+/**
+ * hwmp_route_info_get - Update routing info to originator and transmitter
+ *
+ * @sdata: local mesh subif
+ * @mgmt: mesh management frame
+ * @hwmp_ie: hwmp information element (PREP or PREQ)
+ *
+ * This function updates the path routing information to the originator and the
+ * transmitter of a HWMP PREQ or PREP frame.
+ *
+ * Returns: metric to frame originator or 0 if the frame should not be further
+ * processed
+ *
+ * Notes: this function is the only place (besides user-provided info) where
+ * path routing information is updated.
+ */
+static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
+			    struct ieee80211_mgmt *mgmt,
+			    u8 *hwmp_ie, enum mpath_frame_type action)
+{
+	struct ieee80211_local *local = sdata->local;
+	struct mesh_path *mpath;
+	struct sta_info *sta;
+	bool fresh_info;
+	u8 *orig_addr, *ta;
+	u32 orig_sn, orig_metric;
+	unsigned long orig_lifetime, exp_time;
+	u32 last_hop_metric, new_metric;
+	bool process = true;
+
+	rcu_read_lock();
+	sta = sta_info_get(sdata, mgmt->sa);
+	if (!sta) {
+		rcu_read_unlock();
+		return 0;
+	}
+
+	last_hop_metric = airtime_link_metric_get(local, sta);
+	/* Update and check originator routing info */
+	fresh_info = true;
+
+	switch (action) {
+	case MPATH_PREQ:
+		orig_addr = PREQ_IE_ORIG_ADDR(hwmp_ie);
+		orig_sn = PREQ_IE_ORIG_SN(hwmp_ie);
+		orig_lifetime = PREQ_IE_LIFETIME(hwmp_ie);
+		orig_metric = PREQ_IE_METRIC(hwmp_ie);
+		break;
+	case MPATH_PREP:
+		/* Originator here refers to the MP that was the destination in
+		 * the Path Request. The draft refers to that MP as the
+		 * destination address, even though usually it is the origin of
+		 * the PREP frame. We divert from the nomenclature in the draft
+		 * so that we can easily use a single function to gather path
+		 * information from both PREQ and PREP frames.
+		 */
+		orig_addr = PREP_IE_ORIG_ADDR(hwmp_ie);
+		orig_sn = PREP_IE_ORIG_SN(hwmp_ie);
+		orig_lifetime = PREP_IE_LIFETIME(hwmp_ie);
+		orig_metric = PREP_IE_METRIC(hwmp_ie);
+		break;
+	default:
+		rcu_read_unlock();
+		return 0;
+	}
+	new_metric = orig_metric + last_hop_metric;
+	if (new_metric < orig_metric)
+		new_metric = MAX_METRIC;
+	exp_time = TU_TO_EXP_TIME(orig_lifetime);
+
+	if (memcmp(orig_addr, sdata->vif.addr, ETH_ALEN) == 0) {
+		/* This MP is the originator, we are not interested in this
+		 * frame, except for updating transmitter's path info.
+		 */
+		process = false;
+		fresh_info = false;
+	} else {
+		mpath = mesh_path_lookup(orig_addr, sdata);
+		if (mpath) {
+			spin_lock_bh(&mpath->state_lock);
+			if (mpath->flags & MESH_PATH_FIXED)
+				fresh_info = false;
+			else if ((mpath->flags & MESH_PATH_ACTIVE) &&
+			    (mpath->flags & MESH_PATH_SN_VALID)) {
+				if (SN_GT(mpath->sn, orig_sn) ||
+				    (mpath->sn == orig_sn &&
+				     new_metric >= mpath->metric)) {
+					process = false;
+					fresh_info = false;
+				}
+			}
+		} else {
+			mesh_path_add(orig_addr, sdata);
+			mpath = mesh_path_lookup(orig_addr, sdata);
+			if (!mpath) {
+				rcu_read_unlock();
+				return 0;
+			}
+			spin_lock_bh(&mpath->state_lock);
+		}
+
+		if (fresh_info) {
+			mesh_path_assign_nexthop(mpath, sta);
+			mpath->flags |= MESH_PATH_SN_VALID;
+			mpath->metric = new_metric;
+			mpath->sn = orig_sn;
+			mpath->exp_time = time_after(mpath->exp_time, exp_time)
+					  ?  mpath->exp_time : exp_time;
+			mesh_path_activate(mpath);
+			spin_unlock_bh(&mpath->state_lock);
+			mesh_path_tx_pending(mpath);
+			/* draft says preq_id should be saved to, but there does
+			 * not seem to be any use for it, skipping by now
+			 */
+		} else
+			spin_unlock_bh(&mpath->state_lock);
+	}
+
+	/* Update and check transmitter routing info */
+	ta = mgmt->sa;
+	if (memcmp(orig_addr, ta, ETH_ALEN) == 0)
+		fresh_info = false;
+	else {
+		fresh_info = true;
+
+		mpath = mesh_path_lookup(ta, sdata);
+		if (mpath) {
+			spin_lock_bh(&mpath->state_lock);
+			if ((mpath->flags & MESH_PATH_FIXED) ||
+				((mpath->flags & MESH_PATH_ACTIVE) &&
+					(last_hop_metric > mpath->metric)))
+				fresh_info = false;
+		} else {
+			mesh_path_add(ta, sdata);
+			mpath = mesh_path_lookup(ta, sdata);
+			if (!mpath) {
+				rcu_read_unlock();
+				return 0;
+			}
+			spin_lock_bh(&mpath->state_lock);
+		}
+
+		if (fresh_info) {
+			mesh_path_assign_nexthop(mpath, sta);
+			mpath->flags &= ~MESH_PATH_SN_VALID;
+			mpath->metric = last_hop_metric;
+			mpath->exp_time = time_after(mpath->exp_time, exp_time)
+					  ?  mpath->exp_time : exp_time;
+			mesh_path_activate(mpath);
+			spin_unlock_bh(&mpath->state_lock);
+			mesh_path_tx_pending(mpath);
+		} else
+			spin_unlock_bh(&mpath->state_lock);
+	}
+
+	rcu_read_unlock();
+
+	return process ? new_metric : 0;
+}
+
+static void hwmp_preq_frame_process(struct ieee80211_sub_if_data *sdata,
+				    struct ieee80211_mgmt *mgmt,
+				    u8 *preq_elem, u32 metric)
+{
+	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+	struct mesh_path *mpath;
+	u8 *target_addr, *orig_addr;
+	u8 target_flags, ttl;
+	u32 orig_sn, target_sn, lifetime;
+	bool reply = false;
+	bool forward = true;
+
+	/* Update target SN, if present */
+	target_addr = PREQ_IE_TARGET_ADDR(preq_elem);
+	orig_addr = PREQ_IE_ORIG_ADDR(preq_elem);
+	target_sn = PREQ_IE_TARGET_SN(preq_elem);
+	orig_sn = PREQ_IE_ORIG_SN(preq_elem);
+	target_flags = PREQ_IE_TARGET_F(preq_elem);
+
+	mhwmp_dbg("received PREQ from %pM\n", orig_addr);
+
+	if (memcmp(target_addr, sdata->vif.addr, ETH_ALEN) == 0) {
+		mhwmp_dbg("PREQ is for us\n");
+		forward = false;
+		reply = true;
+		metric = 0;
+		if (time_after(jiffies, ifmsh->last_sn_update +
+					net_traversal_jiffies(sdata)) ||
+		    time_before(jiffies, ifmsh->last_sn_update)) {
+			target_sn = ++ifmsh->sn;
+			ifmsh->last_sn_update = jiffies;
+		}
+	} else {
+		rcu_read_lock();
+		mpath = mesh_path_lookup(target_addr, sdata);
+		if (mpath) {
+			if ((!(mpath->flags & MESH_PATH_SN_VALID)) ||
+					SN_LT(mpath->sn, target_sn)) {
+				mpath->sn = target_sn;
+				mpath->flags |= MESH_PATH_SN_VALID;
+			} else if ((!(target_flags & MP_F_DO)) &&
+					(mpath->flags & MESH_PATH_ACTIVE)) {
+				reply = true;
+				metric = mpath->metric;
+				target_sn = mpath->sn;
+				if (target_flags & MP_F_RF)
+					target_flags |= MP_F_DO;
+				else
+					forward = false;
+			}
+		}
+		rcu_read_unlock();
+	}
+
+	if (reply) {
+		lifetime = PREQ_IE_LIFETIME(preq_elem);
+		ttl = ifmsh->mshcfg.element_ttl;
+		if (ttl != 0) {
+			mhwmp_dbg("replying to the PREQ\n");
+			mesh_path_sel_frame_tx(MPATH_PREP, 0, target_addr,
+				cpu_to_le32(target_sn), 0, orig_addr,
+				cpu_to_le32(orig_sn), mgmt->sa, 0, ttl,
+				cpu_to_le32(lifetime), cpu_to_le32(metric),
+				0, sdata);
+		} else
+			ifmsh->mshstats.dropped_frames_ttl++;
+	}
+
+	if (forward) {
+		u32 preq_id;
+		u8 hopcount, flags;
+
+		ttl = PREQ_IE_TTL(preq_elem);
+		lifetime = PREQ_IE_LIFETIME(preq_elem);
+		if (ttl <= 1) {
+			ifmsh->mshstats.dropped_frames_ttl++;
+			return;
+		}
+		mhwmp_dbg("forwarding the PREQ from %pM\n", orig_addr);
+		--ttl;
+		flags = PREQ_IE_FLAGS(preq_elem);
+		preq_id = PREQ_IE_PREQ_ID(preq_elem);
+		hopcount = PREQ_IE_HOPCOUNT(preq_elem) + 1;
+		mesh_path_sel_frame_tx(MPATH_PREQ, flags, orig_addr,
+				cpu_to_le32(orig_sn), target_flags, target_addr,
+				cpu_to_le32(target_sn), broadcast_addr,
+				hopcount, ttl, cpu_to_le32(lifetime),
+				cpu_to_le32(metric), cpu_to_le32(preq_id),
+				sdata);
+		ifmsh->mshstats.fwded_mcast++;
+		ifmsh->mshstats.fwded_frames++;
+	}
+}
+
+
+static inline struct sta_info *
+next_hop_deref_protected(struct mesh_path *mpath)
+{
+	return rcu_dereference_protected(mpath->next_hop,
+					 lockdep_is_held(&mpath->state_lock));
+}
+
+
+static void hwmp_prep_frame_process(struct ieee80211_sub_if_data *sdata,
+				    struct ieee80211_mgmt *mgmt,
+				    u8 *prep_elem, u32 metric)
+{
+	struct mesh_path *mpath;
+	u8 *target_addr, *orig_addr;
+	u8 ttl, hopcount, flags;
+	u8 next_hop[ETH_ALEN];
+	u32 target_sn, orig_sn, lifetime;
+
+	mhwmp_dbg("received PREP from %pM\n", PREP_IE_ORIG_ADDR(prep_elem));
+
+	/* Note that we divert from the draft nomenclature and denominate
+	 * destination to what the draft refers to as origininator. So in this
+	 * function destnation refers to the final destination of the PREP,
+	 * which corresponds with the originator of the PREQ which this PREP
+	 * replies
+	 */
+	target_addr = PREP_IE_TARGET_ADDR(prep_elem);
+	if (memcmp(target_addr, sdata->vif.addr, ETH_ALEN) == 0)
+		/* destination, no forwarding required */
+		return;
+
+	ttl = PREP_IE_TTL(prep_elem);
+	if (ttl <= 1) {
+		sdata->u.mesh.mshstats.dropped_frames_ttl++;
+		return;
+	}
+
+	rcu_read_lock();
+	mpath = mesh_path_lookup(target_addr, sdata);
+	if (mpath)
+		spin_lock_bh(&mpath->state_lock);
+	else
+		goto fail;
+	if (!(mpath->flags & MESH_PATH_ACTIVE)) {
+		spin_unlock_bh(&mpath->state_lock);
+		goto fail;
+	}
+	memcpy(next_hop, next_hop_deref_protected(mpath)->sta.addr, ETH_ALEN);
+	spin_unlock_bh(&mpath->state_lock);
+	--ttl;
+	flags = PREP_IE_FLAGS(prep_elem);
+	lifetime = PREP_IE_LIFETIME(prep_elem);
+	hopcount = PREP_IE_HOPCOUNT(prep_elem) + 1;
+	orig_addr = PREP_IE_ORIG_ADDR(prep_elem);
+	target_sn = PREP_IE_TARGET_SN(prep_elem);
+	orig_sn = PREP_IE_ORIG_SN(prep_elem);
+
+	mesh_path_sel_frame_tx(MPATH_PREP, flags, orig_addr,
+		cpu_to_le32(orig_sn), 0, target_addr,
+		cpu_to_le32(target_sn), next_hop, hopcount,
+		ttl, cpu_to_le32(lifetime), cpu_to_le32(metric),
+		0, sdata);
+	rcu_read_unlock();
+
+	sdata->u.mesh.mshstats.fwded_unicast++;
+	sdata->u.mesh.mshstats.fwded_frames++;
+	return;
+
+fail:
+	rcu_read_unlock();
+	sdata->u.mesh.mshstats.dropped_frames_no_route++;
+}
+
+static void hwmp_perr_frame_process(struct ieee80211_sub_if_data *sdata,
+			     struct ieee80211_mgmt *mgmt, u8 *perr_elem)
+{
+	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+	struct mesh_path *mpath;
+	u8 ttl;
+	u8 *ta, *target_addr;
+	u32 target_sn;
+	u16 target_rcode;
+
+	ta = mgmt->sa;
+	ttl = PERR_IE_TTL(perr_elem);
+	if (ttl <= 1) {
+		ifmsh->mshstats.dropped_frames_ttl++;
+		return;
+	}
+	ttl--;
+	target_addr = PERR_IE_TARGET_ADDR(perr_elem);
+	target_sn = PERR_IE_TARGET_SN(perr_elem);
+	target_rcode = PERR_IE_TARGET_RCODE(perr_elem);
+
+	rcu_read_lock();
+	mpath = mesh_path_lookup(target_addr, sdata);
+	if (mpath) {
+		spin_lock_bh(&mpath->state_lock);
+		if (mpath->flags & MESH_PATH_ACTIVE &&
+		    memcmp(ta, next_hop_deref_protected(mpath)->sta.addr,
+							ETH_ALEN) == 0 &&
+		    (!(mpath->flags & MESH_PATH_SN_VALID) ||
+		    SN_GT(target_sn, mpath->sn))) {
+			mpath->flags &= ~MESH_PATH_ACTIVE;
+			mpath->sn = target_sn;
+			spin_unlock_bh(&mpath->state_lock);
+			mesh_path_error_tx(ttl, target_addr, cpu_to_le32(target_sn),
+					   cpu_to_le16(target_rcode),
+					   broadcast_addr, sdata);
+		} else
+			spin_unlock_bh(&mpath->state_lock);
+	}
+	rcu_read_unlock();
+}
+
+static void hwmp_rann_frame_process(struct ieee80211_sub_if_data *sdata,
+				struct ieee80211_mgmt *mgmt,
+				struct ieee80211_rann_ie *rann)
+{
+	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+	struct mesh_path *mpath;
+	u8 ttl, flags, hopcount;
+	u8 *orig_addr;
+	u32 orig_sn, metric;
+
+	ttl = rann->rann_ttl;
+	if (ttl <= 1) {
+		ifmsh->mshstats.dropped_frames_ttl++;
+		return;
+	}
+	ttl--;
+	flags = rann->rann_flags;
+	orig_addr = rann->rann_addr;
+	orig_sn = rann->rann_seq;
+	hopcount = rann->rann_hopcount;
+	hopcount++;
+	metric = rann->rann_metric;
+	mhwmp_dbg("received RANN from %pM\n", orig_addr);
+
+	rcu_read_lock();
+	mpath = mesh_path_lookup(orig_addr, sdata);
+	if (!mpath) {
+		mesh_path_add(orig_addr, sdata);
+		mpath = mesh_path_lookup(orig_addr, sdata);
+		if (!mpath) {
+			rcu_read_unlock();
+			sdata->u.mesh.mshstats.dropped_frames_no_route++;
+			return;
+		}
+		mesh_queue_preq(mpath,
+				PREQ_Q_F_START | PREQ_Q_F_REFRESH);
+	}
+	if (mpath->sn < orig_sn) {
+		mesh_path_sel_frame_tx(MPATH_RANN, flags, orig_addr,
+				       cpu_to_le32(orig_sn),
+				       0, NULL, 0, broadcast_addr,
+				       hopcount, ttl, 0,
+				       cpu_to_le32(metric + mpath->metric),
+				       0, sdata);
+		mpath->sn = orig_sn;
+	}
+	rcu_read_unlock();
+}
+
+
+void mesh_rx_path_sel_frame(struct ieee80211_sub_if_data *sdata,
+			    struct ieee80211_mgmt *mgmt,
+			    size_t len)
+{
+	struct ieee802_11_elems elems;
+	size_t baselen;
+	u32 last_hop_metric;
+
+	/* need action_code */
+	if (len < IEEE80211_MIN_ACTION_SIZE + 1)
+		return;
+
+	baselen = (u8 *) mgmt->u.action.u.mesh_action.variable - (u8 *) mgmt;
+	ieee802_11_parse_elems(mgmt->u.action.u.mesh_action.variable,
+			len - baselen, &elems);
+
+	if (elems.preq) {
+		if (elems.preq_len != 37)
+			/* Right now we support just 1 destination and no AE */
+			return;
+		last_hop_metric = hwmp_route_info_get(sdata, mgmt, elems.preq,
+						      MPATH_PREQ);
+		if (last_hop_metric)
+			hwmp_preq_frame_process(sdata, mgmt, elems.preq,
+						last_hop_metric);
+	}
+	if (elems.prep) {
+		if (elems.prep_len != 31)
+			/* Right now we support no AE */
+			return;
+		last_hop_metric = hwmp_route_info_get(sdata, mgmt, elems.prep,
+						      MPATH_PREP);
+		if (last_hop_metric)
+			hwmp_prep_frame_process(sdata, mgmt, elems.prep,
+						last_hop_metric);
+	}
+	if (elems.perr) {
+		if (elems.perr_len != 15)
+			/* Right now we support only one destination per PERR */
+			return;
+		hwmp_perr_frame_process(sdata, mgmt, elems.perr);
+	}
+	if (elems.rann)
+		hwmp_rann_frame_process(sdata, mgmt, elems.rann);
+}
+
+/**
+ * mesh_queue_preq - queue a PREQ to a given destination
+ *
+ * @mpath: mesh path to discover
+ * @flags: special attributes of the PREQ to be sent
+ *
+ * Locking: the function must be called from within a rcu read lock block.
+ *
+ */
+static void mesh_queue_preq(struct mesh_path *mpath, u8 flags)
+{
+	struct ieee80211_sub_if_data *sdata = mpath->sdata;
+	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+	struct mesh_preq_queue *preq_node;
+
+	preq_node = kmalloc(sizeof(struct mesh_preq_queue), GFP_ATOMIC);
+	if (!preq_node) {
+		mhwmp_dbg("could not allocate PREQ node\n");
+		return;
+	}
+
+	spin_lock(&ifmsh->mesh_preq_queue_lock);
+	if (ifmsh->preq_queue_len == MAX_PREQ_QUEUE_LEN) {
+		spin_unlock(&ifmsh->mesh_preq_queue_lock);
+		kfree(preq_node);
+		if (printk_ratelimit())
+			mhwmp_dbg("PREQ node queue full\n");
+		return;
+	}
+
+	memcpy(preq_node->dst, mpath->dst, ETH_ALEN);
+	preq_node->flags = flags;
+
+	list_add_tail(&preq_node->list, &ifmsh->preq_queue.list);
+	++ifmsh->preq_queue_len;
+	spin_unlock(&ifmsh->mesh_preq_queue_lock);
+
+	if (time_after(jiffies, ifmsh->last_preq + min_preq_int_jiff(sdata)))
+		ieee80211_queue_work(&sdata->local->hw, &sdata->work);
+
+	else if (time_before(jiffies, ifmsh->last_preq)) {
+		/* avoid long wait if did not send preqs for a long time
+		 * and jiffies wrapped around
+		 */
+		ifmsh->last_preq = jiffies - min_preq_int_jiff(sdata) - 1;
+		ieee80211_queue_work(&sdata->local->hw, &sdata->work);
+	} else
+		mod_timer(&ifmsh->mesh_path_timer, ifmsh->last_preq +
+						min_preq_int_jiff(sdata));
+}
+
+/**
+ * mesh_path_start_discovery - launch a path discovery from the PREQ queue
+ *
+ * @sdata: local mesh subif
+ */
+void mesh_path_start_discovery(struct ieee80211_sub_if_data *sdata)
+{
+	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+	struct mesh_preq_queue *preq_node;
+	struct mesh_path *mpath;
+	u8 ttl, target_flags;
+	u32 lifetime;
+
+	spin_lock_bh(&ifmsh->mesh_preq_queue_lock);
+	if (!ifmsh->preq_queue_len ||
+		time_before(jiffies, ifmsh->last_preq +
+				min_preq_int_jiff(sdata))) {
+		spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
+		return;
+	}
+
+	preq_node = list_first_entry(&ifmsh->preq_queue.list,
+			struct mesh_preq_queue, list);
+	list_del(&preq_node->list);
+	--ifmsh->preq_queue_len;
+	spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
+
+	rcu_read_lock();
+	mpath = mesh_path_lookup(preq_node->dst, sdata);
+	if (!mpath)
+		goto enddiscovery;
+
+	spin_lock_bh(&mpath->state_lock);
+	if (preq_node->flags & PREQ_Q_F_START) {
+		if (mpath->flags & MESH_PATH_RESOLVING) {
+			spin_unlock_bh(&mpath->state_lock);
+			goto enddiscovery;
+		} else {
+			mpath->flags &= ~MESH_PATH_RESOLVED;
+			mpath->flags |= MESH_PATH_RESOLVING;
+			mpath->discovery_retries = 0;
+			mpath->discovery_timeout = disc_timeout_jiff(sdata);
+		}
+	} else if (!(mpath->flags & MESH_PATH_RESOLVING) ||
+			mpath->flags & MESH_PATH_RESOLVED) {
+		mpath->flags &= ~MESH_PATH_RESOLVING;
+		spin_unlock_bh(&mpath->state_lock);
+		goto enddiscovery;
+	}
+
+	ifmsh->last_preq = jiffies;
+
+	if (time_after(jiffies, ifmsh->last_sn_update +
+				net_traversal_jiffies(sdata)) ||
+	    time_before(jiffies, ifmsh->last_sn_update)) {
+		++ifmsh->sn;
+		sdata->u.mesh.last_sn_update = jiffies;
+	}
+	lifetime = default_lifetime(sdata);
+	ttl = sdata->u.mesh.mshcfg.element_ttl;
+	if (ttl == 0) {
+		sdata->u.mesh.mshstats.dropped_frames_ttl++;
+		spin_unlock_bh(&mpath->state_lock);
+		goto enddiscovery;
+	}
+
+	if (preq_node->flags & PREQ_Q_F_REFRESH)
+		target_flags = MP_F_DO;
+	else
+		target_flags = MP_F_RF;
+
+	spin_unlock_bh(&mpath->state_lock);
+	mesh_path_sel_frame_tx(MPATH_PREQ, 0, sdata->vif.addr,
+			cpu_to_le32(ifmsh->sn), target_flags, mpath->dst,
+			cpu_to_le32(mpath->sn), broadcast_addr, 0,
+			ttl, cpu_to_le32(lifetime), 0,
+			cpu_to_le32(ifmsh->preq_id++), sdata);
+	mod_timer(&mpath->timer, jiffies + mpath->discovery_timeout);
+
+enddiscovery:
+	rcu_read_unlock();
+	kfree(preq_node);
+}
+
+/**
+ * mesh_nexthop_lookup - put the appropriate next hop on a mesh frame
+ *
+ * @skb: 802.11 frame to be sent
+ * @sdata: network subif the frame will be sent through
+ *
+ * Returns: 0 if the next hop was found. Nonzero otherwise. If no next hop is
+ * found, the function will start a path discovery and queue the frame so it is
+ * sent when the path is resolved. This means the caller must not free the skb
+ * in this case.
+ */
+int mesh_nexthop_lookup(struct sk_buff *skb,
+			struct ieee80211_sub_if_data *sdata)
+{
+	struct sk_buff *skb_to_free = NULL;
+	struct mesh_path *mpath;
+	struct sta_info *next_hop;
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+	u8 *target_addr = hdr->addr3;
+	int err = 0;
+
+	rcu_read_lock();
+	mpath = mesh_path_lookup(target_addr, sdata);
+
+	if (!mpath) {
+		mesh_path_add(target_addr, sdata);
+		mpath = mesh_path_lookup(target_addr, sdata);
+		if (!mpath) {
+			sdata->u.mesh.mshstats.dropped_frames_no_route++;
+			err = -ENOSPC;
+			goto endlookup;
+		}
+	}
+
+	if (mpath->flags & MESH_PATH_ACTIVE) {
+		if (time_after(jiffies,
+			       mpath->exp_time -
+			       msecs_to_jiffies(sdata->u.mesh.mshcfg.path_refresh_time)) &&
+		    !memcmp(sdata->vif.addr, hdr->addr4, ETH_ALEN) &&
+		    !(mpath->flags & MESH_PATH_RESOLVING) &&
+		    !(mpath->flags & MESH_PATH_FIXED)) {
+			mesh_queue_preq(mpath,
+					PREQ_Q_F_START | PREQ_Q_F_REFRESH);
+		}
+		next_hop = rcu_dereference(mpath->next_hop);
+		if (next_hop)
+			memcpy(hdr->addr1, next_hop->sta.addr, ETH_ALEN);
+		else
+			err = -ENOENT;
+	} else {
+		struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+		if (!(mpath->flags & MESH_PATH_RESOLVING)) {
+			/* Start discovery only if it is not running yet */
+			mesh_queue_preq(mpath, PREQ_Q_F_START);
+		}
+
+		if (skb_queue_len(&mpath->frame_queue) >=
+				MESH_FRAME_QUEUE_LEN)
+			skb_to_free = skb_dequeue(&mpath->frame_queue);
+
+		info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
+		skb_queue_tail(&mpath->frame_queue, skb);
+		if (skb_to_free)
+			mesh_path_discard_frame(skb_to_free, sdata);
+		err = -ENOENT;
+	}
+
+endlookup:
+	rcu_read_unlock();
+	return err;
+}
+
+void mesh_path_timer(unsigned long data)
+{
+	struct mesh_path *mpath = (void *) data;
+	struct ieee80211_sub_if_data *sdata = mpath->sdata;
+
+	if (sdata->local->quiescing)
+		return;
+
+	spin_lock_bh(&mpath->state_lock);
+	if (mpath->flags & MESH_PATH_RESOLVED ||
+			(!(mpath->flags & MESH_PATH_RESOLVING)))
+		mpath->flags &= ~(MESH_PATH_RESOLVING | MESH_PATH_RESOLVED);
+	else if (mpath->discovery_retries < max_preq_retries(sdata)) {
+		++mpath->discovery_retries;
+		mpath->discovery_timeout *= 2;
+		mesh_queue_preq(mpath, 0);
+	} else {
+		mpath->flags = 0;
+		mpath->exp_time = jiffies;
+		mesh_path_flush_pending(mpath);
+	}
+
+	spin_unlock_bh(&mpath->state_lock);
+}
+
+void
+mesh_path_tx_root_frame(struct ieee80211_sub_if_data *sdata)
+{
+	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+
+	mesh_path_sel_frame_tx(MPATH_RANN, 0, sdata->vif.addr,
+			       cpu_to_le32(++ifmsh->sn),
+			       0, NULL, 0, broadcast_addr,
+			       0, sdata->u.mesh.mshcfg.element_ttl,
+			       0, 0, 0, sdata);
+}