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-rw-r--r--net/llc/llc_input.c189
1 files changed, 189 insertions, 0 deletions
diff --git a/net/llc/llc_input.c b/net/llc/llc_input.c
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+++ b/net/llc/llc_input.c
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+/*
+ * llc_input.c - Minimal input path for LLC
+ *
+ * Copyright (c) 1997 by Procom Technology, Inc.
+ * 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ * This program can be redistributed or modified under the terms of the
+ * GNU General Public License as published by the Free Software Foundation.
+ * This program is distributed without any warranty or implied warranty
+ * of merchantability or fitness for a particular purpose.
+ *
+ * See the GNU General Public License for more details.
+ */
+#include <linux/netdevice.h>
+#include <net/llc.h>
+#include <net/llc_pdu.h>
+#include <net/llc_sap.h>
+
+#if 0
+#define dprintk(args...) printk(KERN_DEBUG args)
+#else
+#define dprintk(args...)
+#endif
+
+/*
+ * Packet handler for the station, registerable because in the minimal
+ * LLC core that is taking shape only the very minimal subset of LLC that
+ * is needed for things like IPX, Appletalk, etc will stay, with all the
+ * rest in the llc1 and llc2 modules.
+ */
+static void (*llc_station_handler)(struct sk_buff *skb);
+
+/*
+ * Packet handlers for LLC_DEST_SAP and LLC_DEST_CONN.
+ */
+static void (*llc_type_handlers[2])(struct llc_sap *sap,
+ struct sk_buff *skb);
+
+void llc_add_pack(int type, void (*handler)(struct llc_sap *sap,
+ struct sk_buff *skb))
+{
+ if (type == LLC_DEST_SAP || type == LLC_DEST_CONN)
+ llc_type_handlers[type - 1] = handler;
+}
+
+void llc_remove_pack(int type)
+{
+ if (type == LLC_DEST_SAP || type == LLC_DEST_CONN)
+ llc_type_handlers[type - 1] = NULL;
+}
+
+void llc_set_station_handler(void (*handler)(struct sk_buff *skb))
+{
+ llc_station_handler = handler;
+}
+
+/**
+ * llc_pdu_type - returns which LLC component must handle for PDU
+ * @skb: input skb
+ *
+ * This function returns which LLC component must handle this PDU.
+ */
+static __inline__ int llc_pdu_type(struct sk_buff *skb)
+{
+ int type = LLC_DEST_CONN; /* I-PDU or S-PDU type */
+ struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
+
+ if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) != LLC_PDU_TYPE_U)
+ goto out;
+ switch (LLC_U_PDU_CMD(pdu)) {
+ case LLC_1_PDU_CMD_XID:
+ case LLC_1_PDU_CMD_UI:
+ case LLC_1_PDU_CMD_TEST:
+ type = LLC_DEST_SAP;
+ break;
+ case LLC_2_PDU_CMD_SABME:
+ case LLC_2_PDU_CMD_DISC:
+ case LLC_2_PDU_RSP_UA:
+ case LLC_2_PDU_RSP_DM:
+ case LLC_2_PDU_RSP_FRMR:
+ break;
+ default:
+ type = LLC_DEST_INVALID;
+ break;
+ }
+out:
+ return type;
+}
+
+/**
+ * llc_fixup_skb - initializes skb pointers
+ * @skb: This argument points to incoming skb
+ *
+ * Initializes internal skb pointer to start of network layer by deriving
+ * length of LLC header; finds length of LLC control field in LLC header
+ * by looking at the two lowest-order bits of the first control field
+ * byte; field is either 3 or 4 bytes long.
+ */
+static inline int llc_fixup_skb(struct sk_buff *skb)
+{
+ u8 llc_len = 2;
+ struct llc_pdu_sn *pdu;
+
+ if (!pskb_may_pull(skb, sizeof(*pdu)))
+ return 0;
+
+ pdu = (struct llc_pdu_sn *)skb->data;
+ if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) == LLC_PDU_TYPE_U)
+ llc_len = 1;
+ llc_len += 2;
+ skb->h.raw += llc_len;
+ skb_pull(skb, llc_len);
+ if (skb->protocol == htons(ETH_P_802_2)) {
+ u16 pdulen = eth_hdr(skb)->h_proto,
+ data_size = ntohs(pdulen) - llc_len;
+
+ skb_trim(skb, data_size);
+ }
+ return 1;
+}
+
+/**
+ * llc_rcv - 802.2 entry point from net lower layers
+ * @skb: received pdu
+ * @dev: device that receive pdu
+ * @pt: packet type
+ *
+ * When the system receives a 802.2 frame this function is called. It
+ * checks SAP and connection of received pdu and passes frame to
+ * llc_{station,sap,conn}_rcv for sending to proper state machine. If
+ * the frame is related to a busy connection (a connection is sending
+ * data now), it queues this frame in the connection's backlog.
+ */
+int llc_rcv(struct sk_buff *skb, struct net_device *dev,
+ struct packet_type *pt)
+{
+ struct llc_sap *sap;
+ struct llc_pdu_sn *pdu;
+ int dest;
+
+ /*
+ * When the interface is in promisc. mode, drop all the crap that it
+ * receives, do not try to analyse it.
+ */
+ if (unlikely(skb->pkt_type == PACKET_OTHERHOST)) {
+ dprintk("%s: PACKET_OTHERHOST\n", __FUNCTION__);
+ goto drop;
+ }
+ skb = skb_share_check(skb, GFP_ATOMIC);
+ if (unlikely(!skb))
+ goto out;
+ if (unlikely(!llc_fixup_skb(skb)))
+ goto drop;
+ pdu = llc_pdu_sn_hdr(skb);
+ if (unlikely(!pdu->dsap)) /* NULL DSAP, refer to station */
+ goto handle_station;
+ sap = llc_sap_find(pdu->dsap);
+ if (unlikely(!sap)) {/* unknown SAP */
+ dprintk("%s: llc_sap_find(%02X) failed!\n", __FUNCTION__,
+ pdu->dsap);
+ goto drop;
+ }
+ /*
+ * First the upper layer protocols that don't need the full
+ * LLC functionality
+ */
+ if (sap->rcv_func) {
+ sap->rcv_func(skb, dev, pt);
+ goto out;
+ }
+ dest = llc_pdu_type(skb);
+ if (unlikely(!dest || !llc_type_handlers[dest - 1]))
+ goto drop;
+ llc_type_handlers[dest - 1](sap, skb);
+out:
+ return 0;
+drop:
+ kfree_skb(skb);
+ goto out;
+handle_station:
+ if (!llc_station_handler)
+ goto drop;
+ llc_station_handler(skb);
+ goto out;
+}
+
+EXPORT_SYMBOL(llc_add_pack);
+EXPORT_SYMBOL(llc_remove_pack);
+EXPORT_SYMBOL(llc_set_station_handler);