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 */ 37 static 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 66 void 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 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) { 86 skb_queue_head(&lapb->write_queue, skb); 87 break; 88 } 89 90 if (skb->sk) 91 skb_set_owner_w(skbn, skb->sk); 92 93 /* 94 * Transmit the frame copy. 95 */ 96 lapb_send_iframe(lapb, skbn, LAPB_POLLOFF); 97 98 lapb->vs = (lapb->vs + 1) % modulus; 99 100 /* 101 * Requeue the original data frame. 102 */ 103 skb_queue_tail(&lapb->ack_queue, skb); 104 105 } while (lapb->vs != end && (skb = skb_dequeue(&lapb->write_queue)) != NULL); 106 107 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION; 108 109 if (!lapb_t1timer_running(lapb)) 110 lapb_start_t1timer(lapb); 111 } 112 } 113 114 void lapb_transmit_buffer(struct lapb_cb *lapb, struct sk_buff *skb, int type) 115 { 116 unsigned char *ptr; 117 118 ptr = skb_push(skb, 1); 119 120 if (lapb->mode & LAPB_MLP) { 121 if (lapb->mode & LAPB_DCE) { 122 if (type == LAPB_COMMAND) 123 *ptr = LAPB_ADDR_C; 124 if (type == LAPB_RESPONSE) 125 *ptr = LAPB_ADDR_D; 126 } else { 127 if (type == LAPB_COMMAND) 128 *ptr = LAPB_ADDR_D; 129 if (type == LAPB_RESPONSE) 130 *ptr = LAPB_ADDR_C; 131 } 132 } else { 133 if (lapb->mode & LAPB_DCE) { 134 if (type == LAPB_COMMAND) 135 *ptr = LAPB_ADDR_A; 136 if (type == LAPB_RESPONSE) 137 *ptr = LAPB_ADDR_B; 138 } else { 139 if (type == LAPB_COMMAND) 140 *ptr = LAPB_ADDR_B; 141 if (type == LAPB_RESPONSE) 142 *ptr = LAPB_ADDR_A; 143 } 144 } 145 146 lapb_dbg(2, "(%p) S%d TX %3ph\n", lapb->dev, lapb->state, skb->data); 147 148 if (!lapb_data_transmit(lapb, skb)) 149 kfree_skb(skb); 150 } 151 152 void lapb_establish_data_link(struct lapb_cb *lapb) 153 { 154 lapb->condition = 0x00; 155 lapb->n2count = 0; 156 157 if (lapb->mode & LAPB_EXTENDED) { 158 lapb_dbg(1, "(%p) S%d TX SABME(1)\n", lapb->dev, lapb->state); 159 lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND); 160 } else { 161 lapb_dbg(1, "(%p) S%d TX SABM(1)\n", lapb->dev, lapb->state); 162 lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND); 163 } 164 165 lapb_start_t1timer(lapb); 166 lapb_stop_t2timer(lapb); 167 } 168 169 void lapb_enquiry_response(struct lapb_cb *lapb) 170 { 171 lapb_dbg(1, "(%p) S%d TX RR(1) R%d\n", 172 lapb->dev, lapb->state, lapb->vr); 173 174 lapb_send_control(lapb, LAPB_RR, LAPB_POLLON, LAPB_RESPONSE); 175 176 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION; 177 } 178 179 void lapb_timeout_response(struct lapb_cb *lapb) 180 { 181 lapb_dbg(1, "(%p) S%d TX RR(0) R%d\n", 182 lapb->dev, lapb->state, lapb->vr); 183 lapb_send_control(lapb, LAPB_RR, LAPB_POLLOFF, LAPB_RESPONSE); 184 185 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION; 186 } 187 188 void lapb_check_iframes_acked(struct lapb_cb *lapb, unsigned short nr) 189 { 190 if (lapb->vs == nr) { 191 lapb_frames_acked(lapb, nr); 192 lapb_stop_t1timer(lapb); 193 lapb->n2count = 0; 194 } else if (lapb->va != nr) { 195 lapb_frames_acked(lapb, nr); 196 lapb_start_t1timer(lapb); 197 } 198 } 199 200 void lapb_check_need_response(struct lapb_cb *lapb, int type, int pf) 201 { 202 if (type == LAPB_COMMAND && pf) 203 lapb_enquiry_response(lapb); 204 } 205