blob: d62e0f9b9da3edca21a8292bc321764aa1866187 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * llc_input.c - Minimal input path for LLC
3 *
4 * Copyright (c) 1997 by Procom Technology, Inc.
5 * 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
6 *
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.
11 *
12 * See the GNU General Public License for more details.
13 */
14#include <linux/netdevice.h>
15#include <net/llc.h>
16#include <net/llc_pdu.h>
17#include <net/llc_sap.h>
18
19#if 0
20#define dprintk(args...) printk(KERN_DEBUG args)
21#else
22#define dprintk(args...)
23#endif
24
25/*
26 * Packet handler for the station, registerable because in the minimal
27 * LLC core that is taking shape only the very minimal subset of LLC that
28 * is needed for things like IPX, Appletalk, etc will stay, with all the
29 * rest in the llc1 and llc2 modules.
30 */
31static void (*llc_station_handler)(struct sk_buff *skb);
32
33/*
34 * Packet handlers for LLC_DEST_SAP and LLC_DEST_CONN.
35 */
36static void (*llc_type_handlers[2])(struct llc_sap *sap,
37 struct sk_buff *skb);
38
39void llc_add_pack(int type, void (*handler)(struct llc_sap *sap,
40 struct sk_buff *skb))
41{
42 if (type == LLC_DEST_SAP || type == LLC_DEST_CONN)
43 llc_type_handlers[type - 1] = handler;
44}
45
46void llc_remove_pack(int type)
47{
48 if (type == LLC_DEST_SAP || type == LLC_DEST_CONN)
49 llc_type_handlers[type - 1] = NULL;
50}
51
52void llc_set_station_handler(void (*handler)(struct sk_buff *skb))
53{
54 llc_station_handler = handler;
55}
56
57/**
58 * llc_pdu_type - returns which LLC component must handle for PDU
59 * @skb: input skb
60 *
61 * This function returns which LLC component must handle this PDU.
62 */
63static __inline__ int llc_pdu_type(struct sk_buff *skb)
64{
65 int type = LLC_DEST_CONN; /* I-PDU or S-PDU type */
66 struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
67
68 if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) != LLC_PDU_TYPE_U)
69 goto out;
70 switch (LLC_U_PDU_CMD(pdu)) {
71 case LLC_1_PDU_CMD_XID:
72 case LLC_1_PDU_CMD_UI:
73 case LLC_1_PDU_CMD_TEST:
74 type = LLC_DEST_SAP;
75 break;
76 case LLC_2_PDU_CMD_SABME:
77 case LLC_2_PDU_CMD_DISC:
78 case LLC_2_PDU_RSP_UA:
79 case LLC_2_PDU_RSP_DM:
80 case LLC_2_PDU_RSP_FRMR:
81 break;
82 default:
83 type = LLC_DEST_INVALID;
84 break;
85 }
86out:
87 return type;
88}
89
90/**
91 * llc_fixup_skb - initializes skb pointers
92 * @skb: This argument points to incoming skb
93 *
94 * Initializes internal skb pointer to start of network layer by deriving
95 * length of LLC header; finds length of LLC control field in LLC header
96 * by looking at the two lowest-order bits of the first control field
97 * byte; field is either 3 or 4 bytes long.
98 */
99static inline int llc_fixup_skb(struct sk_buff *skb)
100{
101 u8 llc_len = 2;
Jochen Friedrich096f0eb2005-09-22 04:48:46 -0300102 struct llc_pdu_un *pdu;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103
Arnaldo Carvalho de Meloaf426d32005-09-22 03:59:22 -0300104 if (unlikely(!pskb_may_pull(skb, sizeof(*pdu))))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105 return 0;
106
Jochen Friedrich096f0eb2005-09-22 04:48:46 -0300107 pdu = (struct llc_pdu_un *)skb->data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) == LLC_PDU_TYPE_U)
109 llc_len = 1;
110 llc_len += 2;
Jochen Friedrich096f0eb2005-09-22 04:48:46 -0300111
112 if (unlikely(!pskb_may_pull(skb, llc_len)))
113 return 0;
114
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115 skb->h.raw += llc_len;
116 skb_pull(skb, llc_len);
117 if (skb->protocol == htons(ETH_P_802_2)) {
118 u16 pdulen = eth_hdr(skb)->h_proto,
119 data_size = ntohs(pdulen) - llc_len;
120
David S. Miller5185db02006-04-19 15:37:13 -0700121 if (unlikely(pskb_trim_rcsum(skb, data_size)))
122 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123 }
124 return 1;
125}
126
127/**
128 * llc_rcv - 802.2 entry point from net lower layers
129 * @skb: received pdu
130 * @dev: device that receive pdu
131 * @pt: packet type
132 *
133 * When the system receives a 802.2 frame this function is called. It
134 * checks SAP and connection of received pdu and passes frame to
135 * llc_{station,sap,conn}_rcv for sending to proper state machine. If
136 * the frame is related to a busy connection (a connection is sending
137 * data now), it queues this frame in the connection's backlog.
138 */
139int llc_rcv(struct sk_buff *skb, struct net_device *dev,
David S. Millerf2ccd8f2005-08-09 19:34:12 -0700140 struct packet_type *pt, struct net_device *orig_dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141{
142 struct llc_sap *sap;
143 struct llc_pdu_sn *pdu;
144 int dest;
145
146 /*
147 * When the interface is in promisc. mode, drop all the crap that it
148 * receives, do not try to analyse it.
149 */
150 if (unlikely(skb->pkt_type == PACKET_OTHERHOST)) {
151 dprintk("%s: PACKET_OTHERHOST\n", __FUNCTION__);
152 goto drop;
153 }
154 skb = skb_share_check(skb, GFP_ATOMIC);
155 if (unlikely(!skb))
156 goto out;
157 if (unlikely(!llc_fixup_skb(skb)))
158 goto drop;
159 pdu = llc_pdu_sn_hdr(skb);
160 if (unlikely(!pdu->dsap)) /* NULL DSAP, refer to station */
161 goto handle_station;
162 sap = llc_sap_find(pdu->dsap);
163 if (unlikely(!sap)) {/* unknown SAP */
164 dprintk("%s: llc_sap_find(%02X) failed!\n", __FUNCTION__,
165 pdu->dsap);
166 goto drop;
167 }
168 /*
169 * First the upper layer protocols that don't need the full
170 * LLC functionality
171 */
172 if (sap->rcv_func) {
David S. Millerf2ccd8f2005-08-09 19:34:12 -0700173 sap->rcv_func(skb, dev, pt, orig_dev);
Arnaldo Carvalho de Melo6e2144b2005-09-22 04:43:05 -0300174 goto out_put;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 }
176 dest = llc_pdu_type(skb);
177 if (unlikely(!dest || !llc_type_handlers[dest - 1]))
Arnaldo Carvalho de Melo6e2144b2005-09-22 04:43:05 -0300178 goto drop_put;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179 llc_type_handlers[dest - 1](sap, skb);
Arnaldo Carvalho de Melo6e2144b2005-09-22 04:43:05 -0300180out_put:
181 llc_sap_put(sap);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182out:
183 return 0;
184drop:
185 kfree_skb(skb);
186 goto out;
Arnaldo Carvalho de Melo6e2144b2005-09-22 04:43:05 -0300187drop_put:
188 kfree_skb(skb);
189 goto out_put;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190handle_station:
191 if (!llc_station_handler)
192 goto drop;
193 llc_station_handler(skb);
194 goto out;
195}
196
197EXPORT_SYMBOL(llc_add_pack);
198EXPORT_SYMBOL(llc_remove_pack);
199EXPORT_SYMBOL(llc_set_station_handler);