1// SPDX-License-Identifier: GPL-2.0-or-later 2/* 3 * LAPB release 002 4 * 5 * This code REQUIRES 2.1.15 or higher/ NET3.038 6 * 7 * History 8 * LAPB 001 Jonathan Naylor Started Coding 9 * LAPB 002 Jonathan Naylor New timer architecture. 10 */ 11 12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 13 14#include <linux/errno.h> 15#include <linux/types.h> 16#include <linux/socket.h> 17#include <linux/in.h> 18#include <linux/kernel.h> 19#include <linux/timer.h> 20#include <linux/string.h> 21#include <linux/sockios.h> 22#include <linux/net.h> 23#include <linux/inet.h> 24#include <linux/skbuff.h> 25#include <linux/slab.h> 26#include <net/sock.h> 27#include <linux/uaccess.h> 28#include <linux/fcntl.h> 29#include <linux/mm.h> 30#include <linux/interrupt.h> 31#include <net/lapb.h> 32 33/* 34 * This procedure is passed a buffer descriptor for an iframe. It builds 35 * the rest of the control part of the frame and then writes it out. 36 */ 37static void lapb_send_iframe(struct lapb_cb *lapb, struct sk_buff *skb, int poll_bit) 38{ 39 unsigned char *frame; 40 41 if (!skb) 42 return; 43 44 if (lapb->mode & LAPB_EXTENDED) { 45 frame = skb_push(skb, 2); 46 47 frame[0] = LAPB_I; 48 frame[0] |= lapb->vs << 1; 49 frame[1] = poll_bit ? LAPB_EPF : 0; 50 frame[1] |= lapb->vr << 1; 51 } else { 52 frame = skb_push(skb, 1); 53 54 *frame = LAPB_I; 55 *frame |= poll_bit ? LAPB_SPF : 0; 56 *frame |= lapb->vr << 5; 57 *frame |= lapb->vs << 1; 58 } 59 60 lapb_dbg(1, "(%p) S%d TX I(%d) S%d R%d\n", 61 lapb->dev, lapb->state, poll_bit, lapb->vs, lapb->vr); 62 63 lapb_transmit_buffer(lapb, skb, LAPB_COMMAND); 64} 65 66void lapb_kick(struct lapb_cb *lapb) 67{ 68 struct sk_buff *skb, *skbn; 69 unsigned short modulus, start, end; 70 71 modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS; 72 start = !skb_peek(&lapb->ack_queue) ? lapb->va : lapb->vs; 73 end = (lapb->va + lapb->window) % modulus; 74 75 if (!(lapb->condition & LAPB_PEER_RX_BUSY_CONDITION) && 76 start != end && skb_peek(&lapb->write_queue)) { 77 lapb->vs = start; 78 79 /* 80 * Dequeue the frame and copy it. 81 */ 82 skb = skb_dequeue(&lapb->write_queue); 83 84 do { 85 skbn = skb_copy(skb, GFP_ATOMIC); 86 if (!skbn) { 87 skb_queue_head(&lapb->write_queue, skb); 88 break; 89 } 90 91 if (skb->sk) 92 skb_set_owner_w(skbn, skb->sk); 93 94 /* 95 * Transmit the frame copy. 96 */ 97 lapb_send_iframe(lapb, skbn, LAPB_POLLOFF); 98 99 lapb->vs = (lapb->vs + 1) % modulus; 100 101 /* 102 * Requeue the original data frame. 103 */ 104 skb_queue_tail(&lapb->ack_queue, skb); 105 106 } while (lapb->vs != end && (skb = skb_dequeue(&lapb->write_queue)) != NULL); 107 108 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION; 109 110 if (!lapb_t1timer_running(lapb)) 111 lapb_start_t1timer(lapb); 112 } 113} 114 115void lapb_transmit_buffer(struct lapb_cb *lapb, struct sk_buff *skb, int type) 116{ 117 unsigned char *ptr; 118 119 ptr = skb_push(skb, 1); 120 121 if (lapb->mode & LAPB_MLP) { 122 if (lapb->mode & LAPB_DCE) { 123 if (type == LAPB_COMMAND) 124 *ptr = LAPB_ADDR_C; 125 if (type == LAPB_RESPONSE) 126 *ptr = LAPB_ADDR_D; 127 } else { 128 if (type == LAPB_COMMAND) 129 *ptr = LAPB_ADDR_D; 130 if (type == LAPB_RESPONSE) 131 *ptr = LAPB_ADDR_C; 132 } 133 } else { 134 if (lapb->mode & LAPB_DCE) { 135 if (type == LAPB_COMMAND) 136 *ptr = LAPB_ADDR_A; 137 if (type == LAPB_RESPONSE) 138 *ptr = LAPB_ADDR_B; 139 } else { 140 if (type == LAPB_COMMAND) 141 *ptr = LAPB_ADDR_B; 142 if (type == LAPB_RESPONSE) 143 *ptr = LAPB_ADDR_A; 144 } 145 } 146 147 lapb_dbg(2, "(%p) S%d TX %3ph\n", lapb->dev, lapb->state, skb->data); 148 149 if (!lapb_data_transmit(lapb, skb)) 150 kfree_skb(skb); 151} 152 153void lapb_establish_data_link(struct lapb_cb *lapb) 154{ 155 lapb->condition = 0x00; 156 lapb->n2count = 0; 157 158 if (lapb->mode & LAPB_EXTENDED) { 159 lapb_dbg(1, "(%p) S%d TX SABME(1)\n", lapb->dev, lapb->state); 160 lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND); 161 } else { 162 lapb_dbg(1, "(%p) S%d TX SABM(1)\n", lapb->dev, lapb->state); 163 lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND); 164 } 165 166 lapb_start_t1timer(lapb); 167 lapb_stop_t2timer(lapb); 168} 169 170void lapb_enquiry_response(struct lapb_cb *lapb) 171{ 172 lapb_dbg(1, "(%p) S%d TX RR(1) R%d\n", 173 lapb->dev, lapb->state, lapb->vr); 174 175 lapb_send_control(lapb, LAPB_RR, LAPB_POLLON, LAPB_RESPONSE); 176 177 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION; 178} 179 180void lapb_timeout_response(struct lapb_cb *lapb) 181{ 182 lapb_dbg(1, "(%p) S%d TX RR(0) R%d\n", 183 lapb->dev, lapb->state, lapb->vr); 184 lapb_send_control(lapb, LAPB_RR, LAPB_POLLOFF, LAPB_RESPONSE); 185 186 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION; 187} 188 189void lapb_check_iframes_acked(struct lapb_cb *lapb, unsigned short nr) 190{ 191 if (lapb->vs == nr) { 192 lapb_frames_acked(lapb, nr); 193 lapb_stop_t1timer(lapb); 194 lapb->n2count = 0; 195 } else if (lapb->va != nr) { 196 lapb_frames_acked(lapb, nr); 197 lapb_start_t1timer(lapb); 198 } 199} 200 201void lapb_check_need_response(struct lapb_cb *lapb, int type, int pf) 202{ 203 if (type == LAPB_COMMAND && pf) 204 lapb_enquiry_response(lapb); 205} 206