Commit | Line | Data |
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1da177e4 LT |
1 | /* |
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 | */ | |
31 | static void (*llc_station_handler)(struct sk_buff *skb); | |
32 | ||
33 | /* | |
34 | * Packet handlers for LLC_DEST_SAP and LLC_DEST_CONN. | |
35 | */ | |
36 | static void (*llc_type_handlers[2])(struct llc_sap *sap, | |
37 | struct sk_buff *skb); | |
38 | ||
39 | void 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 | ||
46 | void 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 | ||
52 | void 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 | */ | |
63 | static __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 | } | |
86 | out: | |
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 | */ | |
99 | static inline int llc_fixup_skb(struct sk_buff *skb) | |
100 | { | |
101 | u8 llc_len = 2; | |
102 | struct llc_pdu_sn *pdu; | |
103 | ||
104 | if (!pskb_may_pull(skb, sizeof(*pdu))) | |
105 | return 0; | |
106 | ||
107 | pdu = (struct llc_pdu_sn *)skb->data; | |
108 | if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) == LLC_PDU_TYPE_U) | |
109 | llc_len = 1; | |
110 | llc_len += 2; | |
111 | skb->h.raw += llc_len; | |
112 | skb_pull(skb, llc_len); | |
113 | if (skb->protocol == htons(ETH_P_802_2)) { | |
114 | u16 pdulen = eth_hdr(skb)->h_proto, | |
115 | data_size = ntohs(pdulen) - llc_len; | |
116 | ||
117 | skb_trim(skb, data_size); | |
118 | } | |
119 | return 1; | |
120 | } | |
121 | ||
122 | /** | |
123 | * llc_rcv - 802.2 entry point from net lower layers | |
124 | * @skb: received pdu | |
125 | * @dev: device that receive pdu | |
126 | * @pt: packet type | |
127 | * | |
128 | * When the system receives a 802.2 frame this function is called. It | |
129 | * checks SAP and connection of received pdu and passes frame to | |
130 | * llc_{station,sap,conn}_rcv for sending to proper state machine. If | |
131 | * the frame is related to a busy connection (a connection is sending | |
132 | * data now), it queues this frame in the connection's backlog. | |
133 | */ | |
134 | int llc_rcv(struct sk_buff *skb, struct net_device *dev, | |
135 | struct packet_type *pt) | |
136 | { | |
137 | struct llc_sap *sap; | |
138 | struct llc_pdu_sn *pdu; | |
139 | int dest; | |
140 | ||
141 | /* | |
142 | * When the interface is in promisc. mode, drop all the crap that it | |
143 | * receives, do not try to analyse it. | |
144 | */ | |
145 | if (unlikely(skb->pkt_type == PACKET_OTHERHOST)) { | |
146 | dprintk("%s: PACKET_OTHERHOST\n", __FUNCTION__); | |
147 | goto drop; | |
148 | } | |
149 | skb = skb_share_check(skb, GFP_ATOMIC); | |
150 | if (unlikely(!skb)) | |
151 | goto out; | |
152 | if (unlikely(!llc_fixup_skb(skb))) | |
153 | goto drop; | |
154 | pdu = llc_pdu_sn_hdr(skb); | |
155 | if (unlikely(!pdu->dsap)) /* NULL DSAP, refer to station */ | |
156 | goto handle_station; | |
157 | sap = llc_sap_find(pdu->dsap); | |
158 | if (unlikely(!sap)) {/* unknown SAP */ | |
159 | dprintk("%s: llc_sap_find(%02X) failed!\n", __FUNCTION__, | |
160 | pdu->dsap); | |
161 | goto drop; | |
162 | } | |
163 | /* | |
164 | * First the upper layer protocols that don't need the full | |
165 | * LLC functionality | |
166 | */ | |
167 | if (sap->rcv_func) { | |
168 | sap->rcv_func(skb, dev, pt); | |
169 | goto out; | |
170 | } | |
171 | dest = llc_pdu_type(skb); | |
172 | if (unlikely(!dest || !llc_type_handlers[dest - 1])) | |
173 | goto drop; | |
174 | llc_type_handlers[dest - 1](sap, skb); | |
175 | out: | |
176 | return 0; | |
177 | drop: | |
178 | kfree_skb(skb); | |
179 | goto out; | |
180 | handle_station: | |
181 | if (!llc_station_handler) | |
182 | goto drop; | |
183 | llc_station_handler(skb); | |
184 | goto out; | |
185 | } | |
186 | ||
187 | EXPORT_SYMBOL(llc_add_pack); | |
188 | EXPORT_SYMBOL(llc_remove_pack); | |
189 | EXPORT_SYMBOL(llc_set_station_handler); |