ieee80211_input.c

Linux下wifi实现

			ni->ni_rxseqs[tid] = rxseq;
		}
	}

	switch (type) {
	case IEEE80211_FC0_TYPE_DATA:
		hdrspace = ieee80211_hdrspace(ic, wh);
		if (skb->len < hdrspace) {
			IEEE80211_DISCARD(vap, IEEE80211_MSG_ANY,
				wh, "data", "too short: len %u, expecting %u",
			 	skb->len, hdrspace);
			vap->iv_stats.is_rx_tooshort++;
			goto out;		/* XXX */
		}
		switch (vap->iv_opmode) {
		case IEEE80211_M_STA:
			if ((dir != IEEE80211_FC1_DIR_FROMDS) &&
			    (!((vap->iv_flags_ext & IEEE80211_FEXT_WDS) &&
			    (dir == IEEE80211_FC1_DIR_DSTODS)))) {
				IEEE80211_DISCARD(vap, IEEE80211_MSG_ANY,
					wh, "data", "invalid dir 0x%x", dir);
				vap->iv_stats.is_rx_wrongdir++;
				goto out;
			}
			if ((dev->flags & IFF_MULTICAST) &&
			    IEEE80211_IS_MULTICAST(wh->i_addr1)) {
				if (IEEE80211_ADDR_EQ(wh->i_addr3, vap->iv_myaddr)) {
					/*
					 * In IEEE802.11 network, multicast packet
					 * sent from me is broadcasted from AP.
					 * It should be silently discarded for
					 * SIMPLEX interface.
					 *
					 * NB: Linux has no IFF_ flag to indicate
					 *     if an interface is SIMPLEX or not;
					 *     so we always assume it to be true.
					 */
					IEEE80211_DISCARD(vap, IEEE80211_MSG_INPUT,
						wh, NULL, "%s", "multicast echo");
					vap->iv_stats.is_rx_mcastecho++;
					goto out;
				}
				/* 
				 * if it is brodcasted by me on behalf of
				 * a station behind me, drop it.
				 */
				if (vap->iv_flags_ext & IEEE80211_FEXT_WDS) {
					struct ieee80211_node_table *nt;
					struct ieee80211_node *ni_wds = NULL;
					nt = &ic->ic_sta;
					ni_wds = ieee80211_find_wds_node(nt, wh->i_addr3);
					if (ni_wds) {
						ieee80211_free_node(ni_wds); /* Decr ref count */
						IEEE80211_DISCARD(vap, IEEE80211_MSG_INPUT,
							wh, NULL, "%s",
							"multicast echo originated from node behind me");
						vap->iv_stats.is_rx_mcastecho++;
						goto out;
					} 
				}
			}
			break;
		case IEEE80211_M_IBSS:
		case IEEE80211_M_AHDEMO:
			if (dir != IEEE80211_FC1_DIR_NODS) {
				IEEE80211_DISCARD(vap, IEEE80211_MSG_ANY,
					wh, "data", "invalid dir 0x%x", dir);
				vap->iv_stats.is_rx_wrongdir++;
				goto out;
			}
			/* XXX no power-save support */
			break;
		case IEEE80211_M_HOSTAP:
			if ((dir != IEEE80211_FC1_DIR_TODS) &&
			    (dir != IEEE80211_FC1_DIR_DSTODS)) {
				IEEE80211_DISCARD(vap, IEEE80211_MSG_ANY,
					wh, "data", "invalid dir 0x%x", dir);
				vap->iv_stats.is_rx_wrongdir++;
				goto out;
			}
			/* check if source STA is associated */
			if (ni == vap->iv_bss) {
				IEEE80211_DISCARD(vap, IEEE80211_MSG_INPUT,
					wh, "data", "%s", "unknown src");
				/* NB: caller deals with reference */
    				if (vap->iv_state == IEEE80211_S_RUN)
					ieee80211_send_error(ni, wh->i_addr2,
						IEEE80211_FC0_SUBTYPE_DEAUTH,
						IEEE80211_REASON_NOT_AUTHED);
				vap->iv_stats.is_rx_notassoc++;
				goto err;
			}
			if (ni->ni_associd == 0) {
				IEEE80211_DISCARD(vap, IEEE80211_MSG_INPUT,
					wh, "data", "%s", "unassoc src");
				IEEE80211_SEND_MGMT(ni,
					IEEE80211_FC0_SUBTYPE_DISASSOC,
					IEEE80211_REASON_NOT_ASSOCED);
				vap->iv_stats.is_rx_notassoc++;
				goto err;
			}
			/*
			 * If we're a 4 address packet, make sure we have an entry in
			 * the node table for the packet source address (addr4).
			 * If not, add one.
			 */
			if (dir == IEEE80211_FC1_DIR_DSTODS) {
				struct ieee80211_node_table *nt;
				struct ieee80211_frame_addr4 *wh4;
				if (!(vap->iv_flags_ext & IEEE80211_FEXT_WDS)) {
					IEEE80211_DISCARD(vap, IEEE80211_MSG_INPUT,
						wh, "data", "%s", "4 addr not allowed");
					goto err;
				}
				wh4 = (struct ieee80211_frame_addr4 *)skb->data;
				nt = &ic->ic_sta;
				ni_wds = ieee80211_find_wds_node(nt, wh4->i_addr4);
				/* Last call increments ref count if !NULL */
				if ((ni_wds != NULL) && (ni_wds != ni)) {
					/*
					 * node with source address (addr4) moved
					 * to another WDS capable station. remove the
					 * reference to the previous station and add 
					 * reference to the new one
					 */
					 (void) ieee80211_remove_wds_addr(nt, wh4->i_addr4);
					 ieee80211_add_wds_addr(nt, ni, wh4->i_addr4, 0);
				}
				if (ni_wds == NULL)
					ieee80211_add_wds_addr(nt, ni, wh4->i_addr4, 0);
				else
					ieee80211_free_node(ni_wds); /* Decr ref count */
			}
			
			/*
			 * Check for power save state change.
			 */
			if (!(ni->ni_flags & IEEE80211_NODE_UAPSD)) {
				if ((wh->i_fc[1] & IEEE80211_FC1_PWR_MGT) ^
				    (ni->ni_flags & IEEE80211_NODE_PWR_MGT))
					ieee80211_node_pwrsave(ni, wh->i_fc[1] & IEEE80211_FC1_PWR_MGT);
			} else if (ni->ni_flags & IEEE80211_NODE_PS_CHANGED) {
				int pwr_save_changed = 0;
				IEEE80211_LOCK_IRQ(ic);
				if ((*(u_int16_t *)(&wh->i_seq[0])) == ni->ni_pschangeseq) {
					ni->ni_flags &= ~IEEE80211_NODE_PS_CHANGED;
					pwr_save_changed = 1;
				}
				IEEE80211_UNLOCK_IRQ(ic);
				if (pwr_save_changed)
					ieee80211_node_pwrsave(ni, wh->i_fc[1] & IEEE80211_FC1_PWR_MGT);
			}
			break;
		case IEEE80211_M_WDS:
			if (dir != IEEE80211_FC1_DIR_DSTODS) {
				IEEE80211_DISCARD(vap, IEEE80211_MSG_ANY,
					wh, "data", "invalid dir 0x%x", dir);
				vap->iv_stats.is_rx_wrongdir++;
				goto out;
			}
			break;
		default:
			/* XXX here to keep compiler happy */
			goto out;
		}

		/*
		 * Handle privacy requirements.  Note that we
		 * must not be preempted from here until after
		 * we (potentially) call ieee80211_crypto_demic;
		 * otherwise we may violate assumptions in the
		 * crypto cipher modules used to do delayed update
		 * of replay sequence numbers.
		 */
		if (wh->i_fc[1] & IEEE80211_FC1_PROT) {
			if ((vap->iv_flags & IEEE80211_F_PRIVACY) == 0) {
				/*
				 * Discard encrypted frames when privacy is off.
				 */
				IEEE80211_DISCARD(vap, IEEE80211_MSG_INPUT,
					wh, "WEP", "%s", "PRIVACY off");
				vap->iv_stats.is_rx_noprivacy++;
				IEEE80211_NODE_STAT(ni, rx_noprivacy);
				goto out;
			}
			key = ieee80211_crypto_decap(ni, skb, hdrspace);
			if (key == NULL) {
				/* NB: stats+msgs handled in crypto_decap */
				IEEE80211_NODE_STAT(ni, rx_wepfail);
				goto out;
			}
			wh = (struct ieee80211_frame *)skb->data;
			wh->i_fc[1] &= ~IEEE80211_FC1_PROT;
		} else
			key = NULL;

		/*
		 * Next up, any fragmentation.
		 */
		if (!IEEE80211_IS_MULTICAST(wh->i_addr1)) {
			skb = ieee80211_defrag(ni, skb, hdrspace);
			if (skb == NULL) {
				/* Fragment dropped or frame not complete yet */
				goto out;
			}
		}
		wh = NULL;		/* no longer valid, catch any uses */

		/*
		 * Next strip any MSDU crypto bits.
		 */
		if (key != NULL &&
		    !ieee80211_crypto_demic(vap, key, skb, hdrspace)) {
			IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_INPUT,
				ni->ni_macaddr, "data", "%s", "demic error");
			IEEE80211_NODE_STAT(ni, rx_demicfail);
			goto out;
		}

		/*
		 * Finally, strip the 802.11 header.
		 */
		skb = ieee80211_decap(vap, skb, hdrspace);
		if (skb == NULL) {
			/* don't count Null data frames as errors */
			if (subtype == IEEE80211_FC0_SUBTYPE_NODATA)
				goto out;
			IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_INPUT,
				ni->ni_macaddr, "data", "%s", "decap error");
			vap->iv_stats.is_rx_decap++;
			IEEE80211_NODE_STAT(ni, rx_decap);
			goto err;
		}
		eh = (struct ether_header *) skb->data;

		if (! accept_data_frame(vap, ni, key, skb, eh))
			goto out;

		vap->iv_devstats.rx_packets++;
		vap->iv_devstats.rx_bytes += skb->len;
		IEEE80211_NODE_STAT(ni, rx_data);
		IEEE80211_NODE_STAT_ADD(ni, rx_bytes, skb->len);
		ic->ic_lastdata = jiffies;

#ifdef ATH_SUPERG_FF
        	/* check for FF */
		llc = (struct llc *) (skb->data + sizeof(struct ether_header));
		if (ntohs(llc->llc_snap.ether_type) == (u_int16_t)ATH_ETH_TYPE) {
			struct sk_buff *skb1 = NULL;
			struct ether_header *eh_tmp;
			struct athl2p_tunnel_hdr *ath_hdr;
			int frame_len;

			/* NB: assumes linear (i.e., non-fragmented) skb */

			/* get to the tunneled headers */
			ath_hdr = (struct athl2p_tunnel_hdr *)
				skb_pull(skb, sizeof(struct ether_header) + LLC_SNAPFRAMELEN);
 			/* ignore invalid frames */
			if(ath_hdr == NULL)
				goto err;
			
			/* only implementing FF now. drop all others. */
			if (ath_hdr->proto != ATH_L2TUNNEL_PROTO_FF) {
				IEEE80211_DISCARD_MAC(vap,
					IEEE80211_MSG_SUPG | IEEE80211_MSG_INPUT,
					eh->ether_shost, "fast-frame",
					"bad atheros tunnel prot %u",
					ath_hdr->proto);
				vap->iv_stats.is_rx_badathtnl++;
				goto err;
			}
			vap->iv_stats.is_rx_ffcnt++;
			
			/* move past the tunneled header, with alignment */
			skb_pull(skb, roundup(sizeof(struct athl2p_tunnel_hdr) - 2, 4) + 2);

			skb1 = skb_clone(skb, GFP_ATOMIC); /* XXX: GFP_ATOMIC is overkill? */
			eh_tmp = (struct ether_header *)skb->data;

			/* ether_type must be length*/
			frame_len = ntohs(eh_tmp->ether_type);

			/* we now have 802.3 MAC hdr followed by 802.2 LLC/SNAP. convert to DIX */
			athff_decap(skb);

			/* remove second frame from end of first */
			skb_trim(skb, sizeof(struct ether_header) + frame_len - LLC_SNAPFRAMELEN);

			/* prepare second tunneled frame */
			skb_pull(skb1, roundup(sizeof(struct ether_header) + frame_len, 4));
			eh_tmp = (struct ether_header *)skb1->data;
			frame_len = ntohs(eh_tmp->ether_type);
			athff_decap(skb1);

			/* deliver the frames */
			ieee80211_deliver_data(ni, skb);
			ieee80211_deliver_data(ni, skb1);
		} else {
			/* assume non-atheros llc type */
			ieee80211_deliver_data(ni, skb);
		}
#else /* !ATH_SUPERG_FF */
		ieee80211_deliver_data(ni, skb);
#endif
		return IEEE80211_FC0_TYPE_DATA;

	case IEEE80211_FC0_TYPE_MGT:
		/*
		 * WDS opmode do not support managment frames
		 */
		if (vap->iv_opmode == IEEE80211_M_WDS) {
			vap->iv_stats.is_rx_mgtdiscard++;
			goto out;
		}
		IEEE80211_NODE_STAT(ni, rx_mgmt);
		if (dir != IEEE80211_FC1_DIR_NODS) {
			vap->iv_stats.is_rx_wrongdir++;
			goto err;
		}
		if (skb->len < sizeof(struct ieee80211_frame)) {
			IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_ANY,
				ni->ni_macaddr, "mgt", "too short: len %u",
				skb->len);
			vap->iv_stats.is_rx_tooshort++;
			goto out;
		}
#ifdef IEEE80211_DEBUG
		if ((ieee80211_msg_debug(vap) && doprint(vap, subtype)) ||
		    ieee80211_msg_dumppkts(vap)) {
			ieee80211_note(vap, "received %s from %s rssi %d\n",
				ieee80211_mgt_subtype_name[subtype >>
				IEEE80211_FC0_SUBTYPE_SHIFT],
				ether_sprintf(wh->i_addr2), rssi);
		}
#endif
		if (wh->i_fc[1] & IEEE80211_FC1_PROT) {
			if (subtype != IEEE80211_FC0_SUBTYPE_AUTH) {
				/*
				 * Only shared key auth frames with a challenge
				 * should be encrypted, discard all others.
				 */
				IEEE80211_DISCARD(vap, IEEE80211_MSG_INPUT,
					wh, ieee80211_mgt_subtype_name[subtype >>
					IEEE80211_FC0_SUBTYPE_SHIFT],
					"%s", "WEP set but not permitted");
				vap->iv_stats.is_rx_mgtdiscard++; /* XXX */
				goto out;
			}
			if ((vap->iv_flags & IEEE80211_F_PRIVACY) == 0) {
				/*
				 * Discard encrypted frames when privacy is off.
				 */
				IEEE80211_DISCARD(vap, IEEE80211_MSG_INPUT,
					wh, "mgt", "%s", "WEP set but PRIVACY off");
				vap->iv_stats.is_rx_noprivacy++;
				goto out;
			}
			hdrspace = ieee80211_hdrspace(ic, wh);
			key = ieee80211_crypto_decap(ni, skb, hdrspace);
			if (key == NULL) {
				/* NB: stats+msgs handled in crypto_decap */
				goto out;
			}
			wh = (struct ieee80211_frame *)skb->data;
			wh->i_fc[1] &= ~IEEE80211_FC1_PROT;
		}
		ic->ic_recv_mgmt(ni, skb, subtype, rssi, rstamp);
		goto out;

	case IEEE80211_FC0_TYPE_CTL:
		IEEE80211_NODE_STAT(ni, rx_ctrl);
		vap->iv_stats.is_rx_ctl++;
		if (vap->iv_opmode == IEEE80211_M_HOSTAP)
			if (subtype == IEEE80211_FC0_SUBTYPE_PS_POLL)
				ieee80211_recv_pspoll(ni, skb);
		goto out;

	default:
		IEEE80211_DISCARD(vap, IEEE80211_MSG_ANY,
			wh, NULL, "bad frame type 0x%x", type);
		/* should not come here */
		break;
	}
err:
	vap->iv_devstats.rx_errors++;
out:
	if (skb != NULL)
		dev_kfree_skb(skb);
	return type;
#undef HAS_SEQ
}
EXPORT_SYMBOL(ieee80211_input);


/*
 * Determines whether a frame should be accepted, based on information
 * about the frame's origin and encryption, and policy for this vap.
 */
static int accept_data_frame(struct ieee80211vap *vap,
       struct ieee80211_node *ni, struct ieee80211_key *key,
       struct sk_buff *skb, struct ether_header *eh)
{
#define IS_EAPOL(eh) ((eh)->ether_type == __constant_htons(ETHERTYPE_PAE))
#define PAIRWISE_SET(vap) ((vap)->iv_nw_keys[0].wk_cipher != &ieee80211_cipher_none)
       if (IS_EAPOL(eh)) {
               /* encrypted eapol is always OK */
               if (key)
                       return 1;
               /* cleartext eapol is OK if we don't have pairwise keys yet */
               if (! PAIRWISE_SET(vap))
                       return 1;
               /* cleartext eapol is OK if configured to allow it */
               if (! IEEE80211_VAP_DROPUNENC_EAPOL(vap))
                       return 1;
               /* cleartext eapol is OK if other unencrypted is OK */
               if (! (vap->iv_flags & IEEE80211_F_DROPUNENC))
                       return 1;
               /* not OK */
               IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_INPUT,
                       eh->ether_shost, "data",
                       "unauthorized port: ether type 0x%x len %u",
                       eh->ether_type, skb->len);
               vap->iv_stats.is_rx_unauth++;
               vap->iv_devstats.rx_errors++;
               IEEE80211_NODE_STAT(ni, rx_unauth);
               return 0;
       }

       if (!ieee80211_node_is_authorized(ni)) {
               /*
                * Deny any non-PAE frames received prior to
                * authorization.  For open/shared-key
                * authentication the port is mark authorized
                * after authentication completes.  For 802.1x
                * the port is not marked authorized by the
                * authenticator until the handshake has completed.
                */
               IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_INPUT,
                       eh->ether_shost, "data",
                       "unauthorized port: ether type 0x%x len %u",
                       eh->ether_type, skb->len);
               vap->iv_stats.is_rx_unauth++;
               vap->iv_devstats.rx_errors++;
               IEEE80211_NODE_STAT(ni, rx_unauth);
               return 0;