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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 18 19 #include <linux/errno.h> 20 #include <linux/types.h> 21 #include <linux/socket.h> 22 #include <linux/in.h> 23 #include <linux/kernel.h> 24 #include <linux/timer.h> 25 #include <linux/string.h> 26 #include <linux/sockios.h> 27 #include <linux/net.h> 28 #include <linux/inet.h> 29 #include <linux/skbuff.h> 30 #include <linux/slab.h> 31 #include <net/sock.h> 32 #include <linux/uaccess.h> 33 #include <linux/fcntl.h> 34 #include <linux/mm.h> 35 #include <linux/interrupt.h> 36 #include <net/lapb.h> 37 38 /* 39 * This procedure is passed a buffer descriptor for an iframe. It builds 40 * the rest of the control part of the frame and then writes it out. 41 */ 42 static void lapb_send_iframe(struct lapb_cb *lapb, struct sk_buff *skb, int poll_bit) 43 { 44 unsigned char *frame; 45 46 if (!skb) 47 return; 48 49 if (lapb->mode & LAPB_EXTENDED) { 50 frame = skb_push(skb, 2); 51 52 frame[0] = LAPB_I; 53 frame[0] |= lapb->vs << 1; 54 frame[1] = poll_bit ? LAPB_EPF : 0; 55 frame[1] |= lapb->vr << 1; 56 } else { 57 frame = skb_push(skb, 1); 58 59 *frame = LAPB_I; 60 *frame |= poll_bit ? LAPB_SPF : 0; 61 *frame |= lapb->vr << 5; 62 *frame |= lapb->vs << 1; 63 } 64 65 lapb_dbg(1, "(%p) S%d TX I(%d) S%d R%d\n", 66 lapb->dev, lapb->state, poll_bit, lapb->vs, lapb->vr); 67 68 lapb_transmit_buffer(lapb, skb, LAPB_COMMAND); 69 } 70 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 } 118 119 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 lapb_dbg(2, "(%p) S%d TX %3ph\n", lapb->dev, lapb->state, skb->data); 152 153 if (!lapb_data_transmit(lapb, skb)) 154 kfree_skb(skb); 155 } 156 157 void lapb_establish_data_link(struct lapb_cb *lapb) 158 { 159 lapb->condition = 0x00; 160 lapb->n2count = 0; 161 162 if (lapb->mode & LAPB_EXTENDED) { 163 lapb_dbg(1, "(%p) S%d TX SABME(1)\n", lapb->dev, lapb->state); 164 lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND); 165 } else { 166 lapb_dbg(1, "(%p) S%d TX SABM(1)\n", lapb->dev, lapb->state); 167 lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND); 168 } 169 170 lapb_start_t1timer(lapb); 171 lapb_stop_t2timer(lapb); 172 } 173 174 void lapb_enquiry_response(struct lapb_cb *lapb) 175 { 176 lapb_dbg(1, "(%p) S%d TX RR(1) R%d\n", 177 lapb->dev, lapb->state, lapb->vr); 178 179 lapb_send_control(lapb, LAPB_RR, LAPB_POLLON, LAPB_RESPONSE); 180 181 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION; 182 } 183 184 void lapb_timeout_response(struct lapb_cb *lapb) 185 { 186 lapb_dbg(1, "(%p) S%d TX RR(0) R%d\n", 187 lapb->dev, lapb->state, lapb->vr); 188 lapb_send_control(lapb, LAPB_RR, LAPB_POLLOFF, LAPB_RESPONSE); 189 190 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION; 191 } 192 193 void lapb_check_iframes_acked(struct lapb_cb *lapb, unsigned short nr) 194 { 195 if (lapb->vs == nr) { 196 lapb_frames_acked(lapb, nr); 197 lapb_stop_t1timer(lapb); 198 lapb->n2count = 0; 199 } else if (lapb->va != nr) { 200 lapb_frames_acked(lapb, nr); 201 lapb_start_t1timer(lapb); 202 } 203 } 204 205 void lapb_check_need_response(struct lapb_cb *lapb, int type, int pf) 206 { 207 if (type == LAPB_COMMAND && pf) 208 lapb_enquiry_response(lapb); 209 } 210