1 /*
2  *	LAPB release 002
3  *
4  *	This code REQUIRES 2.1.15 or higher/ NET3.038
5  *
6  *	This module:
7  *		This module is free software; you can redistribute it and/or
8  *		modify it under the terms of the GNU General Public License
9  *		as published by the Free Software Foundation; either version
10  *		2 of the License, or (at your option) any later version.
11  *
12  *	History
13  *	LAPB 001	Jonathan Naylor	Started Coding
14  *	LAPB 002	Jonathan Naylor	New timer architecture.
15  */
16 
17 #include <linux/errno.h>
18 #include <linux/types.h>
19 #include <linux/socket.h>
20 #include <linux/in.h>
21 #include <linux/kernel.h>
22 #include <linux/timer.h>
23 #include <linux/string.h>
24 #include <linux/sockios.h>
25 #include <linux/net.h>
26 #include <linux/inet.h>
27 #include <linux/skbuff.h>
28 #include <linux/slab.h>
29 #include <net/sock.h>
30 #include <asm/uaccess.h>
31 #include <linux/fcntl.h>
32 #include <linux/mm.h>
33 #include <linux/interrupt.h>
34 #include <net/lapb.h>
35 
36 /*
37  *  This procedure is passed a buffer descriptor for an iframe. It builds
38  *  the rest of the control part of the frame and then writes it out.
39  */
lapb_send_iframe(struct lapb_cb * lapb,struct sk_buff * skb,int poll_bit)40 static void lapb_send_iframe(struct lapb_cb *lapb, struct sk_buff *skb, int poll_bit)
41 {
42 	unsigned char *frame;
43 
44 	if (!skb)
45 		return;
46 
47 	if (lapb->mode & LAPB_EXTENDED) {
48 		frame = skb_push(skb, 2);
49 
50 		frame[0] = LAPB_I;
51 		frame[0] |= lapb->vs << 1;
52 		frame[1] = poll_bit ? LAPB_EPF : 0;
53 		frame[1] |= lapb->vr << 1;
54 	} else {
55 		frame = skb_push(skb, 1);
56 
57 		*frame = LAPB_I;
58 		*frame |= poll_bit ? LAPB_SPF : 0;
59 		*frame |= lapb->vr << 5;
60 		*frame |= lapb->vs << 1;
61 	}
62 
63 #if LAPB_DEBUG > 1
64 	printk(KERN_DEBUG "lapb: (%p) S%d TX I(%d) S%d R%d\n",
65 	       lapb->dev, lapb->state, poll_bit, lapb->vs, lapb->vr);
66 #endif
67 
68 	lapb_transmit_buffer(lapb, skb, LAPB_COMMAND);
69 }
70 
lapb_kick(struct lapb_cb * lapb)71 void lapb_kick(struct lapb_cb *lapb)
72 {
73 	struct sk_buff *skb, *skbn;
74 	unsigned short modulus, start, end;
75 
76 	modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
77 	start = !skb_peek(&lapb->ack_queue) ? lapb->va : lapb->vs;
78 	end   = (lapb->va + lapb->window) % modulus;
79 
80 	if (!(lapb->condition & LAPB_PEER_RX_BUSY_CONDITION) &&
81 	    start != end && skb_peek(&lapb->write_queue)) {
82 		lapb->vs = start;
83 
84 		/*
85 		 * Dequeue the frame and copy it.
86 		 */
87 		skb = skb_dequeue(&lapb->write_queue);
88 
89 		do {
90 			if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
91 				skb_queue_head(&lapb->write_queue, skb);
92 				break;
93 			}
94 
95 			if (skb->sk)
96 				skb_set_owner_w(skbn, skb->sk);
97 
98 			/*
99 			 * Transmit the frame copy.
100 			 */
101 			lapb_send_iframe(lapb, skbn, LAPB_POLLOFF);
102 
103 			lapb->vs = (lapb->vs + 1) % modulus;
104 
105 			/*
106 			 * Requeue the original data frame.
107 			 */
108 			skb_queue_tail(&lapb->ack_queue, skb);
109 
110 		} while (lapb->vs != end && (skb = skb_dequeue(&lapb->write_queue)) != NULL);
111 
112 		lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
113 
114 		if (!lapb_t1timer_running(lapb))
115 			lapb_start_t1timer(lapb);
116 	}
117 }
118 
lapb_transmit_buffer(struct lapb_cb * lapb,struct sk_buff * skb,int type)119 void lapb_transmit_buffer(struct lapb_cb *lapb, struct sk_buff *skb, int type)
120 {
121 	unsigned char *ptr;
122 
123 	ptr = skb_push(skb, 1);
124 
125 	if (lapb->mode & LAPB_MLP) {
126 		if (lapb->mode & LAPB_DCE) {
127 			if (type == LAPB_COMMAND)
128 				*ptr = LAPB_ADDR_C;
129 			if (type == LAPB_RESPONSE)
130 				*ptr = LAPB_ADDR_D;
131 		} else {
132 			if (type == LAPB_COMMAND)
133 				*ptr = LAPB_ADDR_D;
134 			if (type == LAPB_RESPONSE)
135 				*ptr = LAPB_ADDR_C;
136 		}
137 	} else {
138 		if (lapb->mode & LAPB_DCE) {
139 			if (type == LAPB_COMMAND)
140 				*ptr = LAPB_ADDR_A;
141 			if (type == LAPB_RESPONSE)
142 				*ptr = LAPB_ADDR_B;
143 		} else {
144 			if (type == LAPB_COMMAND)
145 				*ptr = LAPB_ADDR_B;
146 			if (type == LAPB_RESPONSE)
147 				*ptr = LAPB_ADDR_A;
148 		}
149 	}
150 
151 #if LAPB_DEBUG > 2
152 	printk(KERN_DEBUG "lapb: (%p) S%d TX %02X %02X %02X\n",
153 	       lapb->dev, lapb->state,
154 	       skb->data[0], skb->data[1], skb->data[2]);
155 #endif
156 
157 	if (!lapb_data_transmit(lapb, skb))
158 		kfree_skb(skb);
159 }
160 
lapb_establish_data_link(struct lapb_cb * lapb)161 void lapb_establish_data_link(struct lapb_cb *lapb)
162 {
163 	lapb->condition = 0x00;
164 	lapb->n2count   = 0;
165 
166 	if (lapb->mode & LAPB_EXTENDED) {
167 #if LAPB_DEBUG > 1
168 		printk(KERN_DEBUG "lapb: (%p) S%d TX SABME(1)\n",
169 		       lapb->dev, lapb->state);
170 #endif
171 		lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);
172 	} else {
173 #if LAPB_DEBUG > 1
174 		printk(KERN_DEBUG "lapb: (%p) S%d TX SABM(1)\n",
175 		       lapb->dev, lapb->state);
176 #endif
177 		lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
178 	}
179 
180 	lapb_start_t1timer(lapb);
181 	lapb_stop_t2timer(lapb);
182 }
183 
lapb_enquiry_response(struct lapb_cb * lapb)184 void lapb_enquiry_response(struct lapb_cb *lapb)
185 {
186 #if LAPB_DEBUG > 1
187 	printk(KERN_DEBUG "lapb: (%p) S%d TX RR(1) R%d\n",
188 	       lapb->dev, lapb->state, lapb->vr);
189 #endif
190 
191 	lapb_send_control(lapb, LAPB_RR, LAPB_POLLON, LAPB_RESPONSE);
192 
193 	lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
194 }
195 
lapb_timeout_response(struct lapb_cb * lapb)196 void lapb_timeout_response(struct lapb_cb *lapb)
197 {
198 #if LAPB_DEBUG > 1
199 	printk(KERN_DEBUG "lapb: (%p) S%d TX RR(0) R%d\n",
200 	       lapb->dev, lapb->state, lapb->vr);
201 #endif
202 	lapb_send_control(lapb, LAPB_RR, LAPB_POLLOFF, LAPB_RESPONSE);
203 
204 	lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
205 }
206 
lapb_check_iframes_acked(struct lapb_cb * lapb,unsigned short nr)207 void lapb_check_iframes_acked(struct lapb_cb *lapb, unsigned short nr)
208 {
209 	if (lapb->vs == nr) {
210 		lapb_frames_acked(lapb, nr);
211 		lapb_stop_t1timer(lapb);
212 		lapb->n2count = 0;
213 	} else if (lapb->va != nr) {
214 		lapb_frames_acked(lapb, nr);
215 		lapb_start_t1timer(lapb);
216 	}
217 }
218 
lapb_check_need_response(struct lapb_cb * lapb,int type,int pf)219 void lapb_check_need_response(struct lapb_cb *lapb, int type, int pf)
220 {
221 	if (type == LAPB_COMMAND && pf)
222 		lapb_enquiry_response(lapb);
223 }
224