2 * llc_input.c - Minimal input path for LLC
4 * Copyright (c) 1997 by Procom Technology, Inc.
5 * 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
7 * This program can be redistributed or modified under the terms of the
8 * GNU General Public License as published by the Free Software Foundation.
9 * This program is distributed without any warranty or implied warranty
10 * of merchantability or fitness for a particular purpose.
12 * See the GNU General Public License for more details.
14 #include <linux/netdevice.h>
15 #include <net/net_namespace.h>
17 #include <net/llc_pdu.h>
18 #include <net/llc_sap.h>
21 #define dprintk(args...) printk(KERN_DEBUG args)
23 #define dprintk(args...)
27 * Packet handler for the station, registerable because in the minimal
28 * LLC core that is taking shape only the very minimal subset of LLC that
29 * is needed for things like IPX, Appletalk, etc will stay, with all the
30 * rest in the llc1 and llc2 modules.
32 static void (*llc_station_handler
)(struct sk_buff
*skb
);
35 * Packet handlers for LLC_DEST_SAP and LLC_DEST_CONN.
37 static void (*llc_type_handlers
[2])(struct llc_sap
*sap
,
40 void llc_add_pack(int type
, void (*handler
)(struct llc_sap
*sap
,
43 if (type
== LLC_DEST_SAP
|| type
== LLC_DEST_CONN
)
44 llc_type_handlers
[type
- 1] = handler
;
47 void llc_remove_pack(int type
)
49 if (type
== LLC_DEST_SAP
|| type
== LLC_DEST_CONN
)
50 llc_type_handlers
[type
- 1] = NULL
;
53 void llc_set_station_handler(void (*handler
)(struct sk_buff
*skb
))
55 llc_station_handler
= handler
;
59 * llc_pdu_type - returns which LLC component must handle for PDU
62 * This function returns which LLC component must handle this PDU.
64 static __inline__
int llc_pdu_type(struct sk_buff
*skb
)
66 int type
= LLC_DEST_CONN
; /* I-PDU or S-PDU type */
67 struct llc_pdu_sn
*pdu
= llc_pdu_sn_hdr(skb
);
69 if ((pdu
->ctrl_1
& LLC_PDU_TYPE_MASK
) != LLC_PDU_TYPE_U
)
71 switch (LLC_U_PDU_CMD(pdu
)) {
72 case LLC_1_PDU_CMD_XID
:
73 case LLC_1_PDU_CMD_UI
:
74 case LLC_1_PDU_CMD_TEST
:
77 case LLC_2_PDU_CMD_SABME
:
78 case LLC_2_PDU_CMD_DISC
:
79 case LLC_2_PDU_RSP_UA
:
80 case LLC_2_PDU_RSP_DM
:
81 case LLC_2_PDU_RSP_FRMR
:
84 type
= LLC_DEST_INVALID
;
92 * llc_fixup_skb - initializes skb pointers
93 * @skb: This argument points to incoming skb
95 * Initializes internal skb pointer to start of network layer by deriving
96 * length of LLC header; finds length of LLC control field in LLC header
97 * by looking at the two lowest-order bits of the first control field
98 * byte; field is either 3 or 4 bytes long.
100 static inline int llc_fixup_skb(struct sk_buff
*skb
)
103 struct llc_pdu_un
*pdu
;
105 if (unlikely(!pskb_may_pull(skb
, sizeof(*pdu
))))
108 pdu
= (struct llc_pdu_un
*)skb
->data
;
109 if ((pdu
->ctrl_1
& LLC_PDU_TYPE_MASK
) == LLC_PDU_TYPE_U
)
113 if (unlikely(!pskb_may_pull(skb
, llc_len
)))
116 skb
->transport_header
+= llc_len
;
117 skb_pull(skb
, llc_len
);
118 if (skb
->protocol
== htons(ETH_P_802_2
)) {
119 __be16 pdulen
= eth_hdr(skb
)->h_proto
;
120 u16 data_size
= ntohs(pdulen
) - llc_len
;
122 if (unlikely(pskb_trim_rcsum(skb
, data_size
)))
129 * llc_rcv - 802.2 entry point from net lower layers
131 * @dev: device that receive pdu
134 * When the system receives a 802.2 frame this function is called. It
135 * checks SAP and connection of received pdu and passes frame to
136 * llc_{station,sap,conn}_rcv for sending to proper state machine. If
137 * the frame is related to a busy connection (a connection is sending
138 * data now), it queues this frame in the connection's backlog.
140 int llc_rcv(struct sk_buff
*skb
, struct net_device
*dev
,
141 struct packet_type
*pt
, struct net_device
*orig_dev
)
144 struct llc_pdu_sn
*pdu
;
146 int (*rcv
)(struct sk_buff
*, struct net_device
*,
147 struct packet_type
*, struct net_device
*);
149 if (dev
->nd_net
!= &init_net
)
153 * When the interface is in promisc. mode, drop all the crap that it
154 * receives, do not try to analyse it.
156 if (unlikely(skb
->pkt_type
== PACKET_OTHERHOST
)) {
157 dprintk("%s: PACKET_OTHERHOST\n", __func__
);
160 skb
= skb_share_check(skb
, GFP_ATOMIC
);
163 if (unlikely(!llc_fixup_skb(skb
)))
165 pdu
= llc_pdu_sn_hdr(skb
);
166 if (unlikely(!pdu
->dsap
)) /* NULL DSAP, refer to station */
168 sap
= llc_sap_find(pdu
->dsap
);
169 if (unlikely(!sap
)) {/* unknown SAP */
170 dprintk("%s: llc_sap_find(%02X) failed!\n", __func__
,
175 * First the upper layer protocols that don't need the full
178 rcv
= rcu_dereference(sap
->rcv_func
);
180 struct sk_buff
*cskb
= skb_clone(skb
, GFP_ATOMIC
);
182 rcv(cskb
, dev
, pt
, orig_dev
);
184 dest
= llc_pdu_type(skb
);
185 if (unlikely(!dest
|| !llc_type_handlers
[dest
- 1]))
187 llc_type_handlers
[dest
- 1](sap
, skb
);
199 if (!llc_station_handler
)
201 llc_station_handler(skb
);
205 EXPORT_SYMBOL(llc_add_pack
);
206 EXPORT_SYMBOL(llc_remove_pack
);
207 EXPORT_SYMBOL(llc_set_station_handler
);