llc_if.c revision c752f0739f09b803aed191c4765a3b6650a08653 
1/*
2 * llc_if.c - Defines LLC interface to upper layer
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/config.h>
15#include <linux/module.h>
16#include <linux/kernel.h>
17#include <linux/netdevice.h>
18#include <asm/errno.h>
19#include <net/llc_if.h>
20#include <net/llc_sap.h>
21#include <net/llc_s_ev.h>
22#include <net/llc_conn.h>
23#include <net/sock.h>
24#include <net/llc_c_ev.h>
25#include <net/llc_c_ac.h>
26#include <net/llc_c_st.h>
27#include <net/tcp_states.h>
28
29u8 llc_mac_null_var[IFHWADDRLEN];
30
31/**
32 *	llc_build_and_send_pkt - Connection data sending for upper layers.
33 *	@sk: connection
34 *	@skb: packet to send
35 *
36 *	This function is called when upper layer wants to send data using
37 *	connection oriented communication mode. During sending data, connection
38 *	will be locked and received frames and expired timers will be queued.
39 *	Returns 0 for success, -ECONNABORTED when the connection already
40 *	closed and -EBUSY when sending data is not permitted in this state or
41 *	LLC has send an I pdu with p bit set to 1 and is waiting for it's
42 *	response.
43 */
44int llc_build_and_send_pkt(struct sock *sk, struct sk_buff *skb)
45{
46	struct llc_conn_state_ev *ev;
47	int rc = -ECONNABORTED;
48	struct llc_sock *llc = llc_sk(sk);
49
50	if (llc->state == LLC_CONN_STATE_ADM)
51		goto out;
52	rc = -EBUSY;
53	if (llc_data_accept_state(llc->state)) { /* data_conn_refuse */
54		llc->failed_data_req = 1;
55		goto out;
56	}
57	if (llc->p_flag) {
58		llc->failed_data_req = 1;
59		goto out;
60	}
61	ev = llc_conn_ev(skb);
62	ev->type      = LLC_CONN_EV_TYPE_PRIM;
63	ev->prim      = LLC_DATA_PRIM;
64	ev->prim_type = LLC_PRIM_TYPE_REQ;
65	skb->dev      = llc->dev;
66	rc = llc_conn_state_process(sk, skb);
67out:
68	return rc;
69}
70
71/**
72 *	llc_establish_connection - Called by upper layer to establish a conn
73 *	@sk: connection
74 *	@lmac: local mac address
75 *	@dmac: destination mac address
76 *	@dsap: destination sap
77 *
78 *	Upper layer calls this to establish an LLC connection with a remote
79 *	machine. This function packages a proper event and sends it connection
80 *	component state machine. Success or failure of connection
81 *	establishment will inform to upper layer via calling it's confirm
82 *	function and passing proper information.
83 */
84int llc_establish_connection(struct sock *sk, u8 *lmac, u8 *dmac, u8 dsap)
85{
86	int rc = -EISCONN;
87	struct llc_addr laddr, daddr;
88	struct sk_buff *skb;
89	struct llc_sock *llc = llc_sk(sk);
90	struct sock *existing;
91
92	laddr.lsap = llc->sap->laddr.lsap;
93	daddr.lsap = dsap;
94	memcpy(daddr.mac, dmac, sizeof(daddr.mac));
95	memcpy(laddr.mac, lmac, sizeof(laddr.mac));
96	existing = llc_lookup_established(llc->sap, &daddr, &laddr);
97	if (existing) {
98		if (existing->sk_state == TCP_ESTABLISHED) {
99			sk = existing;
100			goto out_put;
101		} else
102			sock_put(existing);
103	}
104	sock_hold(sk);
105	rc = -ENOMEM;
106	skb = alloc_skb(0, GFP_ATOMIC);
107	if (skb) {
108		struct llc_conn_state_ev *ev = llc_conn_ev(skb);
109
110		ev->type      = LLC_CONN_EV_TYPE_PRIM;
111		ev->prim      = LLC_CONN_PRIM;
112		ev->prim_type = LLC_PRIM_TYPE_REQ;
113		rc = llc_conn_state_process(sk, skb);
114	}
115out_put:
116	sock_put(sk);
117	return rc;
118}
119
120/**
121 *	llc_send_disc - Called by upper layer to close a connection
122 *	@sk: connection to be closed
123 *
124 *	Upper layer calls this when it wants to close an established LLC
125 *	connection with a remote machine. This function packages a proper event
126 *	and sends it to connection component state machine. Returns 0 for
127 *	success, 1 otherwise.
128 */
129int llc_send_disc(struct sock *sk)
130{
131	u16 rc = 1;
132	struct llc_conn_state_ev *ev;
133	struct sk_buff *skb;
134
135	sock_hold(sk);
136	if (sk->sk_type != SOCK_STREAM || sk->sk_state != TCP_ESTABLISHED ||
137	    llc_sk(sk)->state == LLC_CONN_STATE_ADM ||
138	    llc_sk(sk)->state == LLC_CONN_OUT_OF_SVC)
139		goto out;
140	/*
141	 * Postpone unassigning the connection from its SAP and returning the
142	 * connection until all ACTIONs have been completely executed
143	 */
144	skb = alloc_skb(0, GFP_ATOMIC);
145	if (!skb)
146		goto out;
147	sk->sk_state  = TCP_CLOSING;
148	ev	      = llc_conn_ev(skb);
149	ev->type      = LLC_CONN_EV_TYPE_PRIM;
150	ev->prim      = LLC_DISC_PRIM;
151	ev->prim_type = LLC_PRIM_TYPE_REQ;
152	rc = llc_conn_state_process(sk, skb);
153out:
154	sock_put(sk);
155	return rc;
156}
157
158